TY - MANSCPT TI - The many scales to cosmic homogeneity: Use of multiple tracers from the SDSS AU - Sarkar, Prakash AU - Majumdar, Subhabrata AU - Pandey, Biswajit AU - Kedia, Atul AU - Sarkar, Suman DA - 2016/11// PY - 2016/11// DO - 10.48550/arXiv.1611.07915 ER - TY - CONF TI - Heavy Metals in Dwarf Galaxies AU - Roederer, I.U. T2 - 4th Magellan Science Symposium C2 - 2016/// C3 - 4th Magellan Science Symposium CY - Washington, DC DA - 2016/// PY - 2016/12/7/ ER - TY - CONF TI - Neutron-Capture Elements from the First Stars AU - Roederer, I.U. T2 - First Stars V C2 - 2016/// C3 - First Stars V CY - Heidelberg, Germany DA - 2016/// PY - 2016/8/1/ ER - TY - CONF TI - Different Ways of Thinking about r-process observations AU - Roederer, I.U. T2 - The r-process nucleosynthesis: connecting FRIB with the cosmos C2 - 2016/// C3 - The r-process nucleosynthesis: connecting FRIB with the cosmos CY - East Lansing, MI DA - 2016/// PY - 2016/5/31/ ER - TY - CONF TI - New Observational Constraints from Ancient Stars on the Origins of Heavy Elements AU - Roederer, I.U. T2 - JINA-CEE Frontiers Meeting C2 - 2016/// C3 - JINA-CEE Frontiers Meeting CY - Notre Dame, IN DA - 2016/// PY - 2016/// ER - TY - CONF TI - New Constraints on the r-process Provided by New Observations of Rare Elements in Metal-Poor Stars AU - Roederer, I.U. T2 - JINA-CEE Frontiers Meeting C2 - 2016/// C3 - JINA-CEE Frontiers Meeting CY - East Lansing, MI DA - 2016/// PY - 2016/// ER - TY - JOUR TI - DETAILED CHEMICAL ABUNDANCES IN THEr-PROCESS-RICH ULTRA-FAINT DWARF GALAXY RETICULUM 2 AU - Roederer, Ian U. AU - Mateo, Mario AU - Iii, John I. Bailey AU - Song, Yingyi AU - Bell, Eric F. AU - Crane, Jeffrey D. AU - Loebman, Sarah AU - Nidever, David L. AU - Olszewski, Edward W. AU - Shectman, Stephen A. AU - Thompson, Ian B. AU - Valluri, Monica AU - Walker, Matthew G. T2 - The Astronomical Journal AB - ABSTRACT The ultra-faint dwarf (UFD) galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey. We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/ Magellan Fiber System. We present detailed abundances for as many as 20 elements per star, including 12 elements heavier than the Fe group. We confirm previous detection of high levels of r -process material in Ret 2 (mean [Eu/Fe] = +1.69 ± 0.05) found in three of these stars (mean [Fe/H] = −2.88 ± 0.10). The abundances closely match the r -process pattern found in the well-studied metal-poor halo star CS 22892–052. Such r -process-enhanced stars have not been found in any other UFD galaxy, though their existence has been predicted by at least one model. The fourth star in Ret 2 ([Fe/H] = −3.42 ± 0.20) contains only trace amounts of Sr ([Sr/Fe] = −1.73 ± 0.43) and no detectable heavier elements. One r -process enhanced star is also enhanced in C (natal [C/Fe] ≈ +1.1). This is only the third such star known, which suggests that the nucleosynthesis sites leading to C and r -process enhancements are decoupled. The r -process-deficient star is enhanced in Mg ([Mg/Fe] = +0.81 ± 0.14), and the other three stars show normal levels of α -enhancement (mean [Mg/Fe] = +0.34 ± 0.03). The abundances of other α and Fe-group elements closely resemble those in UFD galaxies and metal-poor halo stars, suggesting that the nucleosynthesis that led to the large r -process enhancements either produced no light elements or produced light-element abundance signatures indistinguishable from normal supernovae. DA - 2016/2/26/ PY - 2016/2/26/ DO - 10.3847/0004-6256/151/3/82 VL - 151 IS - 3 SP - 82 J2 - The Astronomical Journal OP - SN - 1538-3881 UR - http://dx.doi.org/10.3847/0004-6256/151/3/82 DB - Crossref ER - TY - JOUR TI - THE DIVERSE ORIGINS OF NEUTRON-CAPTURE ELEMENTS IN THE METAL-POOR STAR HD 94028: POSSIBLE DETECTION OF PRODUCTS OF i-PROCESS NUCLEOSYNTHESIS* AU - Roederer, Ian U. AU - Karakas, Amanda I. AU - Pignatari, Marco AU - Herwig, Falk T2 - The Astrophysical Journal AB - We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H]=-1.62+/-0.09) star HD94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s-process; e.g., [Pb/Fe]=+0.79+/-0.32) and rapid neutron-capture process (r-process; e.g., [Eu/Fe]=+0.22+/-0.12), including unusually large molybdenum ([Mo/Fe]=+0.97+/-0.16) and ruthenium ([Ru/Fe]=+0.69+/-0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe]=-0.06+/-0.19). We analyze an archival near-ultraviolet spectrum of HD94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99+/-0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (i process), which perhaps operated by the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the i process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the i process may have been common in the early Galaxy. DA - 2016/4/10/ PY - 2016/4/10/ DO - 10.3847/0004-637X/821/1/37 UR - https://doi.org/10.3847/0004-637X/821/1/37 ER - TY - JOUR TI - DETECTION OF PHOSPHORUS, SULPHUR, AND ZINC IN THE CARBON-ENHANCED METAL-POOR STAR BD+44 493* AU - Roederer, Ian U. AU - Placco, Vinicius M. AU - Beers, Timothy C. T2 - The Astrophysical Journal Letters AB - The carbon-enhanced metal-poor star BD+44 493 ([Fe/H]=-3.9) has been proposed as a candidate second-generation star enriched by metals from a single Pop III star. We report the first detections of P and S and the second detection of Zn in any extremely metal-poor carbon-enhanced star, using new spectra of BD+44 493 collected by the Cosmic Origins Spectrograph on the Hubble Space Telescope. We derive [P/Fe]=-0.34 +/- 0.21, [S/Fe]=+0.07 +/- 0.41, and [Zn/Fe]=-0.10 +/- 0.24. We increase by ten-fold the number of Si I lines detected in BD+44 493, yielding [Si/Fe]=+0.15 +/- 0.22. The solar [S/Fe] and [Zn/Fe] ratios exclude the hypothesis that the abundance pattern in BD+44 493 results from depletion of refractory elements onto dust grains. Comparison with zero-metallicity supernova models suggests that the stellar progenitor that enriched BD+44 493 was massive and ejected much less than 0.07 Msun of Ni-56, characteristic of a faint supernova. DA - 2016/6/20/ PY - 2016/6/20/ DO - 10.3847/2041-8205/824/2/L19 UR - https://doi.org/10.3847/2041-8205/824/2/L19 ER - TY - JOUR TI - OBSERVATIONAL CONSTRAINTS ON FIRST-STAR NUCLEOSYNTHESIS. I. EVIDENCE FOR MULTIPLE PROGENITORS OF CEMP-NO STARS AU - Yoon, Jinmi AU - Beers, Timothy C. AU - Placco, Vinicius M. AU - Rasmussen, Kaitlin C. AU - Carollo, Daniela AU - He, Siyu AU - Hansen, Terese T. AU - Roederer, Ian U. AU - Zeanah, Jeff T2 - The Astrophysical Journal AB - We investigate anew the distribution of absolute carbon abundance, $A$(C) $= \log\,\epsilon $(C), for carbon-enhanced metal-poor (CEMP) stars in the halo of the Milky Way, based on high-resolution spectroscopic data for a total sample of 305 CEMP stars. The sample includes 147 CEMP-$s$ (and CEMP-r/s) stars, 127 CEMP-no stars, and 31 CEMP stars that are unclassified, based on the currently employed [Ba/Fe] criterion. We confirm previous claims that the distribution of $A$(C) for CEMP stars is (at least) bimodal, with newly determined peaks centered on $A$(C)$=7.96$ (the high-C region) and $A$(C)$ =6.28$ (the low-C region). A very high fraction of CEMP-$s$ (and CEMP-r/s) stars belong to the high-C region, while the great majority of CEMP-no stars reside in the low-C region. However, there exists complexity in the morphology of the $A$(C)-[Fe/H] space for the CEMP-no stars, a first indication that more than one class of first-generation stellar progenitors may be required to account for their observed abundances. The two groups of CEMP-no stars we identify exhibit clearly different locations in the $A$(Na)-$A$(C) and $A$(Mg)-$A$(C) spaces, also suggesting multiple progenitors. The clear distinction in $A$(C) between the CEMP-$s$ (and CEMP-$r/s$) stars and the CEMP-no stars appears to be $as\ successful$, and $likely\ more\ astrophysically\ fundamental$, for the separation of these sub-classes as the previously recommended criterion based on [Ba/Fe] (and [Ba/Eu]) abundance ratios. This result opens the window for its application to present and future large-scale low- and medium-resolution spectroscopic surveys. DA - 2016/12/5/ PY - 2016/12/5/ DO - 10.3847/0004-637X/833/1/20 VL - 833 IS - 1 SP - 20 J2 - ApJ OP - SN - 1538-4357 UR - http://dx.doi.org/10.3847/0004-637x/833/1/20 DB - Crossref ER - TY - JOUR TI - NEUTRON-CAPTURE ELEMENT ABUNDANCES IN MAGELLANIC CLOUD PLANETARY NEBULAE* AU - Mashburn, A. L. AU - Sterling, N. C. AU - Madonna, S. AU - Dinerstein, Harriet L. AU - Roederer, I. U. AU - Geballe, T. R. T2 - The Astrophysical Journal Letters AB - We present near-infrared spectra of ten planetary nebulae (PNe) in the Large and Small Magellanic Clouds (LMC and SMC), acquired with the FIRE and GNIRS spectrometers on the 6.5-m Baade and 8.1-m Gemini South Telescopes, respectively. We detect Se and/or Kr emission lines in eight of these objects, the first detections of n-capture elements in Magellanic Cloud PNe. Our abundance analysis shows large s-process enrichments of Kr (0.6-1.3 dex) in the six PNe in which it was detected, and Se is enriched by 0.5-0.9 dex in five objects. We also estimate upper limits to Rb and Cd abundances in these objects. Our abundance results for the LMC are consistent with the hypothesis that PNe with 2--3 M$_{\odot}$ progenitors dominate the bright end of the PN luminosity function in young gas-rich galaxies. We find no significant correlations between s-process enrichments and other elemental abundances, central star temperature, or progenitor mass, though this is likely due to our small sample size. We determine S abundances from our spectra and find that [S/H] agrees with [Ar/H] to within 0.2 dex for most objects, but is lower than [O/H] by 0.2-0.4 dex in some PNe, possibly due to O enrichment via third dredge-up. Our results demonstrate that n-capture elements can be detected in PNe belonging to nearby galaxies with ground-based telescopes, allowing s-process enrichments to be studied in PN populations with well-determined distances. DA - 2016/11/1/ PY - 2016/11/1/ DO - 10.3847/2041-8205/831/1/L3 UR - https://doi.org/10.3847/2041-8205/831/1/L3 ER - TY - SOUND TI - Some New Developments in High Precision Beta Spectroscopy in Measurements of Nuclear Beta Decay AU - Young, A.R. DA - 2016/4/15/ PY - 2016/4/15/ ER - TY - CONF TI - A brief overview of ultracold neutron source development and some points of personal interest AU - Young, A.R. T2 - International Workshop: Probing Fundamental Symmetries and Interactions with UCN C2 - 2016/4/11/ C3 - International Workshop: Probing Fundamental Symmetries and Interactions with UCN CY - Mainz, Germany DA - 2016/4/11/ PY - 2016/4/11/ ER - TY - JOUR TI - Searches for chirality-flipping interactions via cyclotron-radiation spectroscopy AU - Garcia, A. AU - Fertl, M. AU - Guigue, M. AU - Kammel, P. AU - Leredde, A. AU - Mueller, P. AU - Robertson, R.G.H. AU - Rybka, G. AU - Savard, G. AU - Swanson, H.E. AU - Vandevender, B.A. AU - Young, A. T2 - Bulletin of the American Physical Society DA - 2016/// PY - 2016/// VL - 61 SP - HG.00004 ER - TY - JOUR TI - Measurement of the beta asymmetry in 19Ne and a new determination of Vud AU - Combs, Dustin AU - Broussard, Leah AU - Calaprice, Frank AU - Jones, Gordon AU - Young, Albert T2 - Bulletin of the American Physical Society DA - 2016/// PY - 2016/// VL - 61 IS - 13 SP - KG.00008 ER - TY - JOUR TI - Cryogenic Testing of the PULSTAR UCN Source AU - White, C. AU - Hawari, A. AU - Huffman, P. AU - Korobkina, E. AU - Leung, K. AU - Medlin, G. AU - Wehring, B. AU - Young, A. T2 - Bulletin of the American Physical Society DA - 2016/// PY - 2016/// VL - 61 IS - 13 SP - DJ.00003 ER - TY - JOUR TI - Development of detector technologies for neutron beta decay measurements AU - Choi, J.H. AU - Cude-Woods, C. AU - Young, A.R. T2 - Bulletin of the American Physical Society DA - 2016/// PY - 2016/// VL - 61 IS - 13 SP - EA.00120 ER - TY - CONF TI - On Neutron Beta Decay Experiments, nEDM and n-nbar Searches AU - Young, A.R. T2 - 83rd Annual Meeting of the Southeastern Section of the APS C2 - 2016/11// C3 - 83rd Annual Meeting of the Southeastern Section of the APS CY - Charlottesville, VA DA - 2016/11// PY - 2016/11// ER - TY - CONF TI - A New Search for Neutron-Anti-Neutron Oscillations AU - Young, A.R. T2 - Physics of fundamental Symmetries and Interactions -- PSI2016 C2 - 2016/10/16/ C3 - Physics of fundamental Symmetries and Interactions -- PSI2016 CY - Paul Scherrer Insitute DA - 2016/10/16/ PY - 2016/10/16/ ER - TY - CONF TI - High Precision Beta Decay Measurements with Polarized Neutrons and Nuclei AU - Young, A.R. T2 - 22nd International Spin Symposium, University of Illinois Urbana-Champaign C2 - 2016/9/25/ C3 - 22nd International Spin Symposium, University of Illinois Urbana-Champaign CY - Champaign, IL DA - 2016/9/25/ PY - 2016/9/25/ ER - TY - JOUR TI - Protein Folding and Structure Prediction from the Ground Up II: AAWSEM for α/β Proteins AU - Chen, Mingchen AU - Lin, Xingcheng AU - Lu, Wei AU - Onuchic, José N. AU - Wolynes, Peter G. T2 - The Journal of Physical Chemistry B AB - The atomistic associative memory, water mediated, structure and energy model (AAWSEM) is an efficient coarse-grained force field with transferable tertiary interactions that incorporates local in sequence energetic biases using structural information derived from all-atom simulations of long segments of the protein. For α helical proteins, the accuracy of structure prediction using AAWSEM has been established previously. In this article, we examine the capability of AAWSEM to predict the structure of α/β proteins. We also elaborate on an iterative approach that uses the structures from a first round of AAWSEM simulation as fragment memories. This iterative scheme improves the quality of the structure prediction and makes the free energy profile more funneled toward native configurations. We explore the use of clustering analyses as a way of evaluating the confidence in various structure prediction models. Clustering using a local relative order parameter (mutual Q) of the predicted structural ensemble turns out to be optimal. The tightest cluster according to mutual Q generally has the most correctly folded structure. Since there is no bioinformatic input, AAWSEM amounts to an ab initio protein structure prediction method that combines the efficiency of coarse-grained simulations with the local structural accuracy that can be achieved from all-atom simulations. DA - 2016/11/11/ PY - 2016/11/11/ DO - 10.1021/acs.jpcb.6b09347 VL - 121 IS - 15 SP - 3473-3482 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/acs.jpcb.6b09347 DB - Crossref ER - TY - JOUR TI - Protein Folding and Structure Prediction from the Ground Up: The Atomistic Associative Memory, Water Mediated, Structure and Energy Model AU - Chen, Mingchen AU - Lin, Xingcheng AU - Zheng, Weihua AU - Onuchic, José N. AU - Wolynes, Peter G. T2 - The Journal of Physical Chemistry B AB - The associative memory, water mediated, structure and energy model (AWSEM) is a coarse-grained force field with transferable tertiary interactions that incorporates local in sequence energetic biases using bioinformatically derived structural information about peptide fragments with locally similar sequences that we call memories. The memory information from the protein data bank (PDB) database guides proper protein folding. The structural information about available sequences in the database varies in quality and can sometimes lead to frustrated free energy landscapes locally. One way out of this difficulty is to construct the input fragment memory information from all-atom simulations of portions of the complete polypeptide chain. In this paper, we investigate this approach first put forward by Kwac and Wolynes in a more complete way by studying the structure prediction capabilities of this approach for six α-helical proteins. This scheme which we call the atomistic associative memory, water mediated, structure and energy model (AAWSEM) amounts to an ab initio protein structure prediction method that starts from the ground up without using bioinformatic input. The free energy profiles from AAWSEM show that atomistic fragment memories are sufficient to guide the correct folding when tertiary forces are included. AAWSEM combines the efficiency of coarse-grained simulations on the full protein level with the local structural accuracy achievable from all-atom simulations of only parts of a large protein. The results suggest that a hybrid use of atomistic fragment memory and database memory in structural predictions may well be optimal for many practical applications. DA - 2016/5/13/ PY - 2016/5/13/ DO - 10.1021/acs.jpcb.6b02451 VL - 120 IS - 33 SP - 8557-8565 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/acs.jpcb.6b02451 DB - Crossref ER - TY - JOUR TI - Lowered pH Leads to Fusion Peptide Release and a Highly Dynamic Intermediate of Influenza Hemagglutinin AU - Lin, Xingcheng AU - Noel, Jeffrey K. AU - Wang, Qinghua AU - Ma, Jianpeng AU - Onuchic, José N. T2 - The Journal of Physical Chemistry B AB - Hemagglutinin (HA), the membrane-bound fusion protein of the influenza virus, enables the entry of virus into host cells via a structural rearrangement. There is strong evidence that the primary trigger for this rearrangement is the low pH environment of a late endosome. To understand the structural basis and the dynamic consequences of the pH trigger, we employed explicit-solvent molecular dynamics simulations to investigate the initial stages of the HA transition. Our results indicate that lowered pH destabilizes HA and speeds up the dissociation of the fusion peptides (FPs). A buried salt bridge between the N-terminus and Asp1122 of HA stem domain locks the FPs and may act as one of the pH sensors. In line with recent observations from simplified protein models, we find that, after the dissociation of FPs, a structural order-disorder transition in a loop connecting the central coiled-coil to the C-terminal domains produces a highly mobile HA. This motion suggests the existence of a long-lived asymmetric or "symmetry-broken" intermediate during the HA conformational change. This intermediate conformation is consistent with models of hemifusion, and its early formation during the conformational change has implications for the aggregation seen in HA activity. DA - 2016/9/1/ PY - 2016/9/1/ DO - 10.1021/acs.jpcb.6b06775 VL - 120 IS - 36 SP - 9654-9660 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/acs.jpcb.6b06775 DB - Crossref ER - TY - CONF TI - Digging on Asteroids: A Laboratory Model of Granular Dynamics in Microgravity AU - Kollmer, Jonathan E. AU - Lindauer, Scott M. AU - Daniels, Karen E. T2 - 15th Biennial ASCE Conference on Engineering, Science, Construction, and Operations in Challenging Environments C2 - 2016/1/12/ C3 - Earth and Space 2016 DA - 2016/1/12/ DO - 10.1061/9780784479971.021 PB - American Society of Civil Engineers UR - http://dx.doi.org/10.1061/9780784479971.021 ER - TY - JOUR TI - TRF2-Mediated Control of Telomere DNA Topology as a Mechanism for Chromosome-End Protection AU - Benarroch-Popivker, Delphine AU - Pisano, Sabrina AU - Mendez-Bermudez, Aaron AU - Lototska, Liudmyla AU - Kaur, Parminder AU - Bauwens, Serge AU - Djerbi, Nadir AU - Latrick, Chrysa M AU - Fraisier, Vincent AU - Pei, Bei AU - others T2 - Molecular Cell DA - 2016/// PY - 2016/// ER - TY - JOUR TI - Functional interplay between SA1 and TRF1 in telomeric DNA binding and DNA--DNA pairing AU - Lin, Jiangguo AU - Countryman, Preston AU - Chen, Haijiang AU - Pan, Hai AU - Fan, Yanlin AU - Jiang, Yunyun AU - Kaur, Parminder AU - Miao, Wang AU - Gurgel, Gisele AU - You, Changjiang AU - others T2 - Nucleic acids research DA - 2016/// PY - 2016/// SP - gkw518 ER - TY - JOUR TI - Decoupling of a neutron interferometer from temperature gradients AU - Saggu, P. AU - Mineeva, T. AU - Arif, M. AU - Cory, D. G. AU - Haun, R. AU - Heacock, B. AU - Huber, M. G. AU - Li, K. AU - Nsofini, J. AU - Sarenac, D. AU - Shahi, C. B. AU - Skavysh, V. AU - Snow, W. M. AU - Werner, S. A. AU - Young, A. R. AU - Pushin, D. A. T2 - Review of Scientific Instruments AB - Neutron interferometry enables precision measurements that are typically operated within elaborate, multi-layered facilities which provide substantial shielding from environmental noise. These facilities are necessary to maintain the coherence requirements in a perfect crystal neutron interferometer which is extremely sensitive to local environmental conditions such as temperature gradients across the interferometer, external vibrations, and acoustic waves. The ease of operation and breadth of applications of perfect crystal neutron interferometry would greatly benefit from a mode of operation which relaxes these stringent isolation requirements. Here, the INDEX Collaboration and National Institute of Standards and Technology demonstrates the functionality of a neutron interferometer in vacuum and characterize the use of a compact vacuum chamber enclosure as a means to isolate the interferometer from spatial temperature gradients and time-dependent temperature fluctuations. The vacuum chamber is found to have no depreciable effect on the performance of the interferometer (contrast) while improving system stability, thereby showing that it is feasible to replace large temperature isolation and control systems with a compact vacuum enclosure for perfect crystal neutron interferometry. DA - 2016/12// PY - 2016/12// DO - 10.1063/1.4971851 VL - 87 IS - 12 SP - 123507 SN - 0034-6748 1089-7623 UR - http://dx.doi.org/10.1063/1.4971851 ER - TY - JOUR TI - Role of Near Substrate and Bulk Polymer Morphology on Out-of-Plane Space-Charge Limited Hole Mobility AU - Turner, Johnathan AU - Gadisa, Abay T2 - ACS Applied Materials & Interfaces AB - Charge transport is a central issue in all types of organic electronic devices. In organic films, charge transport is crucially limited by film microstructure and the nature of the substrate/organic interface interactions. In this report, we discuss the influence of active layer thickness on space-charge limited hole transport in pristine polymer and polymer/fullerene bulk heterojunction thin films (∼15–300 nm) in a diode structure. According to the results, the out-of-plane hole mobility in pristine polymers is sensitive to the degree of polymer chain aggregation. Blending the polymers with a fullerene molecule does not change the trend of hole mobility if the polymer tends to make an amorphous structure. However, employing an aggregating polymer in a bulk heterojunction blend gives rise to a marked difference in charge carrier transport behavior compared to the pristine polymer and this difference is sensitive to active layer thickness. In aggregating polymer films, the thickness-dependent interchain interaction was found to have direct impact on hole mobility. The thickness-dependent mobility trend was found to correspond well with the trend of fill factors of corresponding bulk heterojunction solar cells. This investigation has a vital implication for material design and the development of efficient organic electronic devices, including solar cells and light-emitting diodes. DA - 2016/11/22/ PY - 2016/11/22/ DO - 10.1021/ACSAMI.6B11232 VL - 8 IS - 48 SP - 33019-33024 J2 - ACS Appl. Mater. Interfaces LA - en OP - SN - 1944-8244 1944-8252 UR - http://dx.doi.org/10.1021/ACSAMI.6B11232 DB - Crossref KW - mobility KW - morphology KW - transport KW - thickness-dependent KW - bulk heterojunction KW - solar cell ER - TY - JOUR TI - Gains and Losses in PbS Quantum Dot Solar Cells with Submicron Periodic Grating Structures AU - Hara, Yukihiro AU - Gadisa, Abay AU - Fu, Yulan AU - Garvey, Timothy AU - Vrouwenvelder, Kristina T. AU - Miller, Christopher W. AU - Dempsey, Jillian L. AU - Lopez, Rene T2 - The Journal of Physical Chemistry C AB - Corrugated structures are integral to many types of photoelectronic devices, used essentially for the manipulation of optical energy inputs. Here, we have investigated the gains and losses incurred by this microscale geometrical change. We have employed nanostructured electrode gratings of 600 nm pitch in PbS colloidal quantum dot (PbS-CQD) solar cells and investigated their effect on photovoltaic properties. Solar cells employing grating structure achieved a 32% and 20% increase in short-circuit current density (Jsc) and power conversion efficiency, respectively, compared to nonstructured reference cells. The observed photocurrent increase of the structured devices mainly stems from the enhancement of photon absorption due to the trapping of optical energy by the grating structures. This optical absorption enhancement was particularly high in the near-infrared portion of the sun spectrum where PbS-based solar cells commonly present poor absorption. We have interestingly observed that the open-circuit voltage of all the devices increase with the increase in the absorbed photon energy (at a fixed light intensity), indicating a significant shift in Fermi energy level due to localization of low photon energy generated carriers in the tail of the density of states. We elucidate the role of the grating structure on charge dynamics and discuss the feasibility of these structures for construction of cheap and efficient photovoltaic devices. DA - 2016/4/13/ PY - 2016/4/13/ DO - 10.1021/ACS.JPCC.6B01498 VL - 120 IS - 15 SP - 8005-8013 J2 - J. Phys. Chem. C LA - en OP - SN - 1932-7447 1932-7455 UR - http://dx.doi.org/10.1021/ACS.JPCC.6B01498 DB - Crossref ER - TY - JOUR TI - Back Cover: Magnetoelectric oxide films for spin manipulation in graphene (Phys. Status Solidi RRL 3/2016) AU - Stuart, S. C. AU - Gray, B. AU - Nevola, D. AU - Su, L. AU - Sachet, E. AU - Ulrich, M. AU - Dougherty, D. B. T2 - physica status solidi (RRL) - Rapid Research Letters AB - No abstract is available for this article. DA - 2016/3// PY - 2016/3// DO - 10.1002/PSSR.201670718 VL - 10 IS - 3 SN - 1862-6254 UR - http://dx.doi.org/10.1002/PSSR.201670718 ER - TY - JOUR TI - Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and their magnetic coupling with ferromagnetic surface: first-principles study AU - Jiang, W AU - Zhou, M AU - Liu, Z AU - Sun, D AU - Vardeny, Z V AU - Liu, F T2 - Journal of Physics: Condensed Matter AB - Using first-principles calculations, we have systematically investigated the structural, electronic, and magnetic properties of facial (fac-) and meridional (mer-) tris(8-hydroxyquinoline)iron(III) (Feq3) molecules and their interaction with ferromagnetic substrate. Our calculation results show that for the isolated Feq3, mer-Feq3 is more stable than the fac-Feq3; both Feq3 isomers have a high spin-state of 5 μB as the ground state when an on-site Hubbard-U term is included to treat the highly localized Fe 3d electrons; while the standard DFT calculations produce a low spin-state of 1 μB for mer-Feq3. These magnetic behaviors can be understood by the octahedral ligand field splitting theory. Furthermore, we found that fac-Feq3 has a stronger bonding to the Co surface than mer-Feq3 and an anti-ferromagnetic coupling was discovered between Fe and Co substrate, originating from the superexchange coupling between Fe and Co mediated by the interface oxygen and nitrogen atoms. These findings suggest that Feq3 molecular films may serve as a promising spin-filter material in spintronic devices. DA - 2016/4/5/ PY - 2016/4/5/ DO - 10.1088/0953-8984/28/17/176004 VL - 28 IS - 17 SP - 176004 J2 - J. Phys.: Condens. Matter OP - SN - 0953-8984 1361-648X UR - http://dx.doi.org/10.1088/0953-8984/28/17/176004 DB - Crossref KW - organic spintronics KW - molecular magnetism KW - surface/interface physics ER - TY - JOUR TI - Status of the MAJORANA DEMONSTRATOR: A search for neutrinoless double-beta decay T2 - International Journal of Modern Physics A AB - If neutrinos are Majorana particles, i.e. fermions that are their own antiparticles, then neutrinoless double-beta (0νββ) decay is possible. In such a process, two neutrons can simultaneously decay into two protons and two electrons without emitting neutrinos. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and might play a role in the matter–antimatter asymmetry in the universe. The MAJORANA DEMONSTRATOR experiment is under construction at the Sanford Underground Research Facility in Lead, SD and will search for the neutrinoless double-beta (0νββ) decay of the 76 Ge isotope. The goal of the experiment is to demonstrate that it is possible to achieve a sufficiently low background rate in the 4 keV region of interest (ROI) around the 2039 keV Q-value to justify building a tonne-scale experiment. In this paper, we discuss the physics and design of the MAJORANA DEMONSTRATOR, its approach to achieving ultra-low background and the status of the experiment. DA - 2016/// PY - 2016/// DO - 10.1142/S0217751X1530032X UR - https://publons.com/wos-op/publon/7238988/ KW - Neutrinoless double beta decay KW - germanium detector KW - Majorana ER - TY - JOUR TI - The PROSPECT physics program T2 - Journal of Physics G: Nuclear and Particle Physics AB - The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and probe eV-scale sterile neutrinos by searching for neutrino oscillations over meter-long distances. PROSPECT is conceived as a 2-phase experiment utilizing segmented $^6$Li-doped liquid scintillator detectors for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT Phase I consists of a movable 3-ton antineutrino detector at distances of 7 - 12 m from the reactor core. It will probe the best-fit point of the $\nu_e$ disappearance experiments at 4$\sigma$ in 1 year and the favored region of the sterile neutrino parameter space at $>$3$\sigma$ in 3 years. With a second antineutrino detector at 15 - 19 m from the reactor, Phase II of PROSPECT can probe the entire allowed parameter space below 10 eV$^{2}$ at 5$\sigma$ in 3 additional years. The measurement of the reactor antineutrino spectrum and the search for short-baseline oscillations with PROSPECT will test the origin of the spectral deviations observed in recent $\theta_{13}$ experiments, search for sterile neutrinos, and conclusively address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly. DA - 2016/// PY - 2016/// DO - 10.1088/0954-3899/43/11/113001 UR - https://publons.com/wos-op/publon/58085533/ KW - reactor neutrino experiments KW - scintillator detectors KW - neutrino oscillation KW - research reactors ER - TY - JOUR TI - Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector T2 - The European Physical Journal C AB - A search for Pauli-exclusion-principle-violating K $$_{\alpha }$$ electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of $$5.8\times 10^{30}$$ s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of $$6.8\times 10^{30}$$ s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of $$^{76}$$ Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation. DA - 2016/// PY - 2016/// DO - 10.1140/EPJC/S10052-016-4467-0 UR - https://publons.com/wos-op/publon/7239026/ ER - TY - JOUR TI - The Majorana Demonstrator radioassay program AU - Abgrall, N. AU - Arnquist, I.J. AU - Avignone, F.T., III AU - Back, H.O. AU - Barabash, A.S. AU - Bertrand, F.E. AU - Boswell, M. AU - Bradley, A.W. AU - Brudanin, V. AU - Busch, M. AU - Buuck, M. AU - Byram, D. AU - Caldwell, A.S. AU - Chan, Y.-D. AU - Christofferson, C.D. AU - Chu, P.-H. AU - Cuesta, C. AU - Detwiler, J.A. AU - Dunmore, J.A. AU - Efremenko, Yu. AU - Ejiri, H. AU - Elliott, S.R. AU - Finnerty, P. AU - Galindo-Uribarri, A. AU - Gehman, V.M. AU - Gilliss, T. AU - Giovanetti, G.K. AU - Goett, J. AU - Green, M.P. AU - Gruszko, J. AU - Guinn, I.S. AU - Guiseppe, V.E. AU - Henning, R. AU - Hoppe, E.W. AU - Howard, S. AU - Howe, M.A. AU - Jasinski, B.R. AU - Johnson, R.A. AU - Keeter, K.J. AU - Kidd, M.F. AU - Kochetov, O. AU - Konovalov, S.I. AU - Kouzes, R.T. AU - LaFerriere, B.D. AU - Leon, J. AU - Loach, J.C. AU - MacMullin, J. AU - MacMullin, S. AU - Martin, R.D. AU - Massarczyk, R. AU - Meijer, S. AU - Mertens, S. AU - Miller, M.L. AU - Orrell, J.L. AU - O'Shaughnessy, C. AU - Overman, N.R. AU - Poon, A.W.P. AU - Pushkin, K. AU - Radford, D.C. AU - Rager, J. AU - Rielage, K. AU - Robertson, R.G.H. AU - Romero-Romero, E. AU - Ronquest, M.C. AU - Schubert, A.G. AU - Shanks, B. AU - Shirchenko, M. AU - Snavely, K.J. AU - Snyder, N. AU - Steele, D. AU - Suriano, A.M. AU - Tedeschi, D. AU - Trimble, J.E. AU - Varner, R.L. AU - Vasilyev, S. AU - Vetter, K. AU - Vorren, K. AU - White, B.R. AU - Wilkerson, J.F. AU - Wiseman, C. AU - Xu, W. AU - Yakushev, E. AU - Yu, C.-H. AU - Yumatov, V. AU - Zhitnikov, I. T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - The Majorana collaboration is constructing the Majorana Demonstrator at the Sanford Underground Research Facility at the Homestake gold mine, in Lead, SD. The apparatus will use Ge detectors, enriched in isotope 76Ge, to demonstrate the feasibility of a large-scale Ge detector experiment to search for neutrinoless double beta decay. The long half-life of this postulated process requires that the apparatus be extremely low in radioactive isotopes whose decays may produce backgrounds to the search. The radioassay program conducted by the collaboration to ensure that the materials comprising the apparatus are sufficiently pure is described. The resulting measurements from gamma-ray counting, neutron activation and mass spectroscopy of the radioactive-isotope contamination for the materials studied for use in the detector are reported. We interpret these numbers in the context of the expected background for the experiment. DA - 2016/8// PY - 2016/8// DO - 10.1016/J.NIMA.2016.04.070 VL - 828 SP - 22-36 J2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment LA - en OP - SN - 0168-9002 UR - http://dx.doi.org/10.1016/J.NIMA.2016.04.070 DB - Crossref KW - Radiopurity KW - Trace analysis KW - Neutron activation analysis KW - Mass spectrometry KW - Mass spectroscopy KW - Germanium counting KW - Low background KW - Double beta decay KW - MAJORANA ER - TY - JOUR TI - Status of the MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-Beta Decay T2 - Advanced Series on Directions in High Energy Physics DA - 2016/// PY - 2016/// UR - https://publons.com/wos-op/publon/26944620/ ER - TY - JOUR TI - High voltage testing for the Majorana Demonstrator AU - Abgrall, N. AU - Arnquist, I.J. AU - Avignone, F.T., III AU - Barabash, A.S. AU - Bertrand, F.E. AU - Bradley, A.W. AU - Brudanin, V. AU - Busch, M. AU - Buuck, M. AU - Byram, D. AU - Caldwell, A.S. AU - Chan, Y-D. AU - Christofferson, C.D. AU - Chu, P.-H. AU - Cuesta, C. AU - Detwiler, J.A. AU - Doe, P.J. AU - Dunagan, C. AU - Efremenko, Yu. AU - Ejiri, H. AU - Elliott, S.R. AU - Fu, Z. AU - Galindo-Uribarri, A. AU - Giovanetti, G.K. AU - Goett, J. AU - Green, M.P. AU - Gruszko, J. AU - Guinn, I.S. AU - Guiseppe, V.E. AU - Henning, R. AU - Hoppe, E.W. AU - Howard, S. AU - Howe, M.A. AU - Jasinski, B.R. AU - Keeter, K.J. AU - Kidd, M.F. AU - Konovalov, S.I. AU - Kouzes, R.T. AU - LaFerriere, B.D. AU - Leon, J. AU - Li, A. AU - MacMullin, J. AU - Martin, R.D. AU - Massarczyk, R. AU - Meijer, S.J. AU - Mertens, S. AU - Orrell, J.L. AU - O'Shaughnessy, C. AU - Poon, A.W.P. AU - Radford, D.C. AU - Rager, J. AU - Rielage, K. AU - Robertson, R.G.H. AU - Romero-Romero, E. AU - Shanks, B. AU - Shirchenko, M. AU - Snyder, N. AU - Suriano, A.M. AU - Tedeschi, D. AU - Thompson, A. AU - Ton, K.T. AU - Trimble, J.E. AU - Varner, R.L. AU - Vasilyev, S. AU - Vetter, K. AU - Vorren, K. AU - White, B.R. AU - Wilkerson, J.F. AU - Wiseman, C. AU - Xu, W. AU - Yakushev, E. AU - Yu, C.-H. AU - Yumatov, V. T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - The MAJORANA Collaboration is constructing the MAJORANA Demonstrator, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in Ge-76. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of the MAJORANA Demonstrator. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of the high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the MAJORANA Demonstrator was characterized and the micro-discharge effects during the MAJORANA Demonstrator commissioning phase were studied. A stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge. DA - 2016/7// PY - 2016/7// DO - 10.1016/J.NIMA.2016.04.006 VL - 823 SP - 83-90 J2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment LA - en OP - SN - 0168-9002 UR - http://dx.doi.org/10.1016/J.NIMA.2016.04.006 DB - Crossref KW - High-voltage KW - Micro-discharge KW - Vacuum KW - MAJORANA ER - TY - JOUR TI - Background radiation measurements at high power research reactors T2 - Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment AB - Research reactors host a wide range of activities that make use of the intense neutron fluxes generated at these facilities. Recent interest in performing measurements with relatively low event rates, e.g. reactor antineutrino detection, at these facilities necessitates a detailed understanding of background radiation fields. Both reactor-correlated and naturally occurring background sources are potentially important, even at levels well below those of importance for typical activities. Here we describe a comprehensive series of background assessments at three high-power research reactors, including γ-ray, neutron, and muon measurements. For each facility we describe the characteristics and identify the sources of the background fields encountered. The general understanding gained of background production mechanisms and their relationship to facility features will prove valuable for the planning of any sensitive measurement conducted therein. DA - 2016/// PY - 2016/// DO - 10.1016/J.NIMA.2015.10.023 UR - https://publons.com/wos-op/publon/6787421/ KW - Research reactors KW - Background measurements KW - Reactor antineutrino detection ER - TY - JOUR TI - Reduction of Additive Colored Noise Using Coupled Dynamics AU - Kohar, Vivek AU - Kia, Behnam AU - Lindner, John F. AU - Ditto, William L. T2 - International Journal of Bifurcation and Chaos AB - We study the effect of additive colored noise on the evolution of maps and demonstrate that the deviations caused by such noise can be reduced using coupled dynamics. We consider both Ornstein–Uhlenbeck process as well as [Formula: see text] noise in our numerical simulations. We observe that though the variance of deviations caused by noise depends on the correlations in the noise, under optimal coupling strength, it decreases by a factor equal to the number of coupled elements in the array as compared to the variance of deviations in a single isolated map. This reduction in noise levels occurs in chaotic as well as periodic regime of the maps. Lastly, we examine the effect of colored noise in chaos computing and find that coupling the chaos computing elements enhances the robustness of chaos computing. DA - 2016/1// PY - 2016/1// DO - 10.1142/s021812741650005x VL - 26 IS - 01 SP - 1650005 J2 - Int. J. Bifurcation Chaos LA - en OP - SN - 0218-1274 1793-6551 UR - http://dx.doi.org/10.1142/s021812741650005x DB - Crossref KW - Coupled map lattice KW - colored noise KW - 1/f(alpha) noise KW - Ornstein-Uhlenbeck process KW - chaos computing ER - TY - JOUR TI - Enhanced emissive and lasing characteristics of nano-crystalline MAPbBr3 films grown via anti-solvent precipitation AU - Lafalce, E. AU - Zhang, C. AU - Zhai, Y. AU - Sun, D. AU - Vardeny, Z. V. T2 - Journal of Applied Physics AB - Control of the nano-scale crystal size distribution in films of organic-inorganic lead-tri-bromide perovskites is achieved through a recently reported solution-based, anti-solvent treatment method [H. Cho et al., Science 350, 1222 (2015)]. The treated films are shown to be high quality, optically smooth with excellent emissive and optical gain properties including higher photoluminescence yield and reduced threshold for laser action. The improved lasing is shown to originate from a synergistic combination of a reduction in waveguide losses and a decrease in the non-radiative decay rate of the excited state population, compared to untreated films. The net gain is increased by a factor of two upon anti-solvent treatment and reaches a respectable value of ≈300 cm−1. DA - 2016/10/10/ PY - 2016/10/10/ DO - 10.1063/1.4964417 VL - 120 IS - 14 SP - 143101 J2 - J. Appl. Phys. LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.4964417 DB - Crossref ER - TY - JOUR TI - Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin–orbit coupling AU - Sun, Dali AU - van Schooten, Kipp J. AU - Kavand, Marzieh AU - Malissa, Hans AU - Zhang, Chuang AU - Groesbeck, Matthew AU - Boehme, Christoph AU - Valy Vardeny, Z. T2 - Nature Materials AB - Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics applications. Owing to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation. This strong ISHE enables us to investigate a variety of OSECs ranging from π-conjugated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the curvature of the molecule's surface. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin currents at room temperature, and paves the way for spin orbitronics in plastic materials. DA - 2016/4/18/ PY - 2016/4/18/ DO - 10.1038/NMAT4618 VL - 15 IS - 8 SP - 863-869 J2 - Nature Mater LA - en OP - SN - 1476-1122 1476-4660 UR - http://dx.doi.org/10.1038/NMAT4618 DB - Crossref ER - TY - JOUR TI - Organic Light-Emitting Diodes: Magnetic Field Enhancement of Organic Light-Emitting Diodes Based on Electron Donor-Acceptor Exciplex (Adv. Electron. Mater. 2/2016) AU - Basel, Tek AU - Sun, Dali AU - Baniya, Sangita AU - McLaughlin, Ryan AU - Choi, Hyeonho AU - Kwon, Ohyun AU - Vardeny, Z. Valy T2 - Advanced Electronic Materials AB - The electroluminescence intensity of pristine organic light emitting diodes based on donor-acceptor exciplexes is significantly enhanced upon application of an external magnetic field, as demonstrated by Basel et al. in article number 1500248. This magneto-electroluminescence causes enhancements of up to 40%, and supported by magneto-photoluminescence measurements shows the importance of reverse intersystem crossing in such systems. DA - 2016/2// PY - 2016/2// DO - 10.1002/AELM.201670012 VL - 2 IS - 2 J2 - Adv. Electron. Mater. LA - en OP - SN - 2199-160X UR - http://dx.doi.org/10.1002/AELM.201670012 DB - Crossref ER - TY - JOUR TI - Magnetic Field Effect in Organic Light-Emitting Diodes Based on Electron Donor-Acceptor Exciplex Chromophores Doped with Fluorescent Emitters AU - Baniya, Sangita AU - Pang, Zhiyong AU - Sun, Dali AU - Zhai, Yaxin AU - Kwon, Ohyun AU - Choi, Hyeonho AU - Choi, Byoungki AU - Lee, Sangyoon AU - Vardeny, Z. Valy T2 - Advanced Functional Materials AB - A new type of organic light‐emitting diode (OLED) has emerged that shows enhanced operational stability and large internal quantum efficiency approaching 100%, which is based on thermally activated delayed fluorescence (TADF) compounds doped with fluorescent emitters. Magneto‐electroluminescence (MEL) in such TADF‐based OLEDs and magneto‐photoluminescence (MPL) in thin films based on donor–acceptor (D–A) exciplexes doped with fluorescent emitters with various concentrations are investigated. It has been found that both MEL and MPL responses are thermally activated with substantially lower activation energy compared to that in the pristine undoped D–A exciplex host blend. In addition, both MPL and MEL steeply decrease with the emitter's concentration. This indicates the existence of a loss mechanism, whereby the triplet charge‐transfer state in the exciplex host blend may directly decay to the lowest, nonemissive triplet state of the fluorescent emitter molecules. DA - 2016/8/18/ PY - 2016/8/18/ DO - 10.1002/ADFM.201601669 VL - 26 IS - 38 SP - 6930-6937 J2 - Adv. Funct. Mater. LA - en OP - SN - 1616-301X UR - http://dx.doi.org/10.1002/ADFM.201601669 DB - Crossref ER - TY - JOUR TI - Effective theory of 3H and 3He T2 - Journal of Physics G: Nuclear and Particle Physics AB - We present a new perturbative expansion for pionless effective field theory with Coulomb interactions in which at leading order (LO) the spin-singlet nucleon–nucleon channels are taken in the unitarity limit. Presenting results up to next-to-leading order for the Phillips line and the neutron–deuteron doublet-channel phase shift, we find that a perturbative expansion in the inverse scattering lengths converges rapidly. Using a new systematic treatment of the proton–proton sector that isolates the divergence due to one-photon exchange, we renormalize the corresponding contribution to the – binding energy splitting and demonstrate that the Coulomb force in pionless EFT is a completely perturbative effect in the trinucleon bound-state regime. In our new expansion, the LO is exactly isospin-symmetric. At next-to-leading order, we include isospin breaking via the Coulomb force and two-body scattering lengths, and find for the energy splitting . DA - 2016/6/1/ PY - 2016/6/1/ DO - 10.1088/0954-3899/43/5/055106 UR - http://dx.doi.org/10.1088/0954-3899/43/5/055106 ER - TY - JOUR TI - The proton–deuteron scattering length in pionless EFT AU - König, Sebastian AU - Hammer, Hans-Werner T2 - EPJ Web of Conferences AB - We present a fully perturbative calculation of the quartet-channel proton–deuteron scattering length (4ap–d) up to next-to-next-to-leading order (NNLO) in pionless effective field theory. In particular, we use a framework that consistently extracts the Coulomb-modified effective range function for a screened Coulomb potential in momentum space. We find a natural convergence pattern as we go to higher orders in the EFT expansion. Our NNLO result of (10.9 ± 0.4) fm agrees with older experimental determinations but deviates from more recent calculations, which find values around 14 fm. To resolve this discrepancy, we discuss the scheme dependence of Coulomb subtractions in a three-body system. DA - 2016/// PY - 2016/// DO - 10.1051/epjconf/201611304011 VL - 113 SP - 04011 ER - TY - JOUR TI - Noise-induced synchronization in a system with a 1/f power spectrum AU - Koverda, V.P. AU - Skokov, V.N. T2 - Physica A: Statistical Mechanics and its Applications AB - A spatially distributed system with 1/f fluctuations at coupled nonequilibrium phase transitions have been simulated by two nonlinear stochastic equations. It is shown numerically that at sufficiently high intensity of white noise in the system there arises noise-induced synchronization, which is a nonequilibrium phase transition. To the critical point of the nonequilibrium phase transition corresponds the 1/f power spectrum and the maximum of informational entropy. DA - 2016/// PY - 2016/// DO - 10.1016/j.physa.2016.02.016 VL - 452 SP - 126-132 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84959249896&partnerID=MN8TOARS KW - Stochastic synchronization KW - 1/f noise KW - Nonequilibrium phase transitions KW - Informational entropy ER - TY - JOUR TI - Fluctuations and waves in a spatially distributed system with the 1/f spectrum AU - Koverda, V.P. AU - Skokov, V.N. T2 - Doklady Physics DA - 2016/// PY - 2016/// DO - 10.1134/S1028335816110094 VL - 61 IS - 11 SP - 535-538 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85002136618&partnerID=MN8TOARS ER - TY - JOUR TI - Erratum to: “Special elements of the lattice of epigroup varieties” (Algebra Univers, 10.1007/s00012-016-0380-5) AU - Shaprynski?, V.Y. AU - Skokov, D.V. AU - Vernikov, B.M. T2 - Algebra Universalis DA - 2016/// PY - 2016/// DO - 10.1007/s00012-016-0383-2 VL - 76 IS - 1 SP - 31 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84975166683&partnerID=MN8TOARS ER - TY - JOUR TI - How tetraquarks can generate a second chiral phase transition AU - Pisarski, Robert D. AU - Skokov, Vladimir V. T2 - Physical Review D AB - We consider how tetraquarks can affect the chiral phase transition in theories like QCD, with light quarks coupled to three colors. For two flavors the tetraquark field is an isosinglet, and its effect is minimal. For three flavors, however, the tetraquark field transforms in the same representation of the chiral symmetry group as the usual chiral order parameter, and so for very light quarks there may be two chiral phase transitions, which are both of first order. In QCD, results from the lattice indicate that any transition from the tetraquark condensate is a smooth crossover. In the plane of temperature and quark chemical potential, though, a crossover line for the tetraquark condensate is naturally related to the transition line for color superconductivity. For four flavors we suggest that a triquark field, antisymmetric in both flavor and color, combine to form hexaquarks. DA - 2016/// PY - 2016/// DO - 10.1103/PhysRevD.94.054008 VL - 94 IS - 5 SP - 054008 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84990913983&partnerID=MN8TOARS ER - TY - JOUR TI - Stochastic resonance in the crisis boiling regime under periodic heat release AU - Skokov, V.N. AU - Vinogradov, A.V. AU - Reshetnikov, A.V. AU - Koverda, V.P. T2 - High Temperature DA - 2016/// PY - 2016/// DO - 10.1134/S0018151X16030196 VL - 54 IS - 3 SP - 344-348 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84977151358&partnerID=MN8TOARS ER - TY - JOUR TI - Cos (4φ) azimuthal anisotropy in small- x DIS dijet production beyond the leading power TMD limit AU - Dumitru, Adrian AU - Skokov, Vladimir T2 - Physical Review D AB - We determine the first correction to the quadrupole operator in high-energy QCD beyond the transverse momentum dependent (TMD) limit of Weizs\"acker-Williams and linearly polarized gluon distributions. These functions give rise to isotropic, respectively, $\ensuremath{\sim}\mathrm{cos}2\ensuremath{\phi}$ angular distributions in deep inelastic scattering (DIS) dijet production. On the other hand, the correction produces a $\ensuremath{\sim}\mathrm{cos}4\ensuremath{\phi}$ angular dependence which is suppressed by one additional power of the dijet transverse momentum scale (squared) ${P}^{2}$. DA - 2016/// PY - 2016/// DO - 10.1103/PhysRevD.94.014030 VL - 94 IS - 1 SP - 014030 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84979658568&partnerID=MN8TOARS ER - TY - JOUR TI - Stochastic synchronization in a spatially distributed system with 1/f power spectrum AU - Koverda, V.P. AU - Skokov, V.N. T2 - Technical Physics DA - 2016/// PY - 2016/// DO - 10.1134/S1063784216080168 VL - 61 IS - 8 SP - 1135-1140 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84981557087&partnerID=MN8TOARS ER - TY - JOUR TI - Special elements of the lattice of epigroup varieties AU - Shaprynski?, V.Y. AU - Skokov, D.V. AU - Vernikov, B.M. T2 - Algebra Universalis AB - We study special elements of three types (namely, neutral, modular and upper-modular elements) in the lattice of all epigroup varieties. Neutral elements are completely determined (it turns out that only four varieties have this property). We find a strong necessary condition for modular elements that completely reduces the problem of description of corresponding varieties to nilvarieties satisfying identities of some special type. Modular elements are completely classified within the class of commutative varieties, while upper-modular elements are completely determined within the wider class of strongly permutative varieties. DA - 2016/// PY - 2016/// DO - 10.1007/s00012-016-0380-5 VL - 76 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84961118916&partnerID=MN8TOARS KW - epigroup KW - variety of epigroups KW - lattice KW - neutral element KW - modular element KW - upper-modular element ER - TY - JOUR TI - Finite numbers of sources, particle correlations and the Color Glass Condensate AU - McLerran, Larry AU - Skokov, Vladimir T2 - Nuclear Physics A AB - We show that for a finite number of emitting sources, the Color Glass Condensate produces substantial elliptic azimuthal anisotropy, characterized by $v_2$, for two and four particle correlations for momentum greater than or of the order the saturation momentum. The flow produced has the correct semi-quantitative features to describe flow seen in LHC experiments with p-Pb and pp collisions. This flow is induced by quantum mechanical interference between the waves of produced particles, and the flow itself is coupled to fluctuations in the positions of emitting sources. We shortly discuss generalizing these results to odd $v_n$, to correlations involving larger number of particles, and to transverse momentum scales $\Lambda_{\rm QCD} \ll p_T \ll Q_{\rm sat}$. DA - 2016/// PY - 2016/// DO - 10.1016/j.nuclphysa.2015.12.005 VL - 947 SP - 142-154 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84953310375&partnerID=MN8TOARS ER - TY - JOUR TI - Chiral matrix model of the semi-QGP in QCD AU - Pisarski, Robert D. AU - Skokov, Vladimir V. T2 - Physical Review D AB - Previously, a matrix model of the region near the transition temperature, in the ``semi''quark gluon plasma, was developed for the theory of $SU(3)$ gluons without quarks. In this paper we develop a chiral matrix model applicable to QCD by including dynamical quarks with $2+1$ flavors. This requires adding a nonet of scalar fields, with both parities, and coupling these to quarks through a Yukawa coupling, $y$. Treating the scalar fields in mean field approximation, the effective Lagrangian is computed by integrating out quarks to one loop order. As is standard, the potential for the scalar fields is chosen to be symmetric under the flavor symmetry of $SU(3{)}_{L}\ifmmode\times\else\texttimes\fi{}SU(3{)}_{R}\ifmmode\times\else\texttimes\fi{}Z(3{)}_{A}$, except for a term linear in the current quark mass, ${m}_{\mathrm{qk}}$. In addition, at a nonzero temperature $T$ it is necessary to add a new term, $\ensuremath{\sim}{m}_{\mathrm{qk}}{T}^{2}$. The parameters of the gluon part of the matrix model are identical to those for the pure glue theory without quarks. The parameters in the chiral matrix model are fixed by the values, at zero temperature, of the pion decay constant and the masses of the pions, kaons, $\ensuremath{\eta}$, and ${\ensuremath{\eta}}^{\ensuremath{'}}$. The temperature for the chiral crossover at ${T}_{\ensuremath{\chi}}=155\text{ }\text{ }\mathrm{MeV}$ is determined by adjusting the Yukawa coupling $y$. We find reasonable agreement with the results of numerical simulations on the lattice for the pressure and related quantities. In the chiral limit, besides the divergence in the chiral susceptibility there is also a milder divergence in the susceptibility between the Polyakov loop and the chiral order parameter, with critical exponent $\ensuremath{\beta}\ensuremath{-}1$. We compute derivatives with respect to a quark chemical potential to determine the susceptibilities for baryon number, the ${\ensuremath{\chi}}_{2n}$. Especially sensitive tests are provided by ${\ensuremath{\chi}}_{4}\ensuremath{-}{\ensuremath{\chi}}_{2}$ and by ${\ensuremath{\chi}}_{6}$, which changes in sign about ${T}_{\ensuremath{\chi}}$. The behavior of the susceptibilities in the chiral matrix model strongly suggests that as the temperature increases from ${T}_{\ensuremath{\chi}}$, that the transition to deconfinement is significantly quicker than indicated by the measurements of the (renormalized) Polyakov loop on the lattice. DA - 2016/// PY - 2016/// DO - 10.1103/PhysRevD.94.034015 VL - 94 IS - 3 SP - 034015 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84982824759&partnerID=MN8TOARS ER - TY - JOUR TI - Centrality dependence of high energy jets in p+Pb collisions at energies available at the CERN Large Hadron Collider AU - Bzdak, Adam AU - Skokov, Vladimir AU - Bathe, Stefan T2 - Physical Review C AB - The recently measured centrality dependence of high energy jets in proton-lead collisions at the CERN Large Hadron Collider (LHC) is investigated. We hypothesize that events with jets of very high energy (a few hundred GeV) are characterized by a suppressed number of soft particles, thus shifting these events into more peripheral bins. This naturally results in the suppression (enhancement) of the nuclear modification factor, ${R}_{pA}$, in central (peripheral) collisions. Our calculations suggest that a moderate suppression of the order of $20%$, for ${10}^{3}$ GeV jets, can quantitatively reproduce the experimental data. We further extract the suppression factor as a function of jet energy and test our conjecture using available ${R}_{pA}$ data for various centralities. DA - 2016/// PY - 2016/// DO - 10.1103/PhysRevC.93.044901 VL - 93 IS - 4 SP - 044901 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84963647583&partnerID=MN8TOARS ER - TY - JOUR TI - Chiral matrix model for the phase transition in QCD AU - Pisarski, R.D. AU - Skokov, V. T2 - Nuclear Physics A AB - We discuss how to model chiral symmetry restoration with an effective theory of deconfinement. The model includes fluctuations in the quarks to one loop order, while the mesons of the sigma model are treated in mean field approximation. We note that a new counterterm is required at T=0, and a novel form of symmetry breaking at T≠0. We discuss how to incorporate tetraquark states, representing JP=0+ scalar mesons, into a linear sigma model. We suggest that their effect upon the chiral phase transition is small. DA - 2016/// PY - 2016/// DO - 10.1016/j.nuclphysa.2016.02.005 VL - 956 SP - 673-676 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84992146521&partnerID=MN8TOARS KW - semi-QGP KW - sigma model ER - TY - JOUR TI - The decay pattern of the Pygmy Dipole Resonance of 140Ce AU - Löher, B. AU - Savran, D. AU - Aumann, T. AU - Beller, J. AU - Bhike, M. AU - Cooper, N. AU - Derya, V. AU - Duchêne, M. AU - Endres, J. AU - Hennig, A. AU - Humby, P. AU - Isaak, J. AU - Kelley, J.H. AU - Knörzer, M. AU - Pietralla, N. AU - Ponomarev, V.Yu. AU - Romig, C. AU - Scheck, M. AU - Scheit, H. AU - Silva, J. AU - Tonchev, A.P. AU - Tornow, W. AU - Wamers, F. AU - Weller, H. AU - Werner, V. AU - Zilges, A. T2 - Physics Letters B AB - The decay properties of the Pygmy Dipole Resonance (PDR) have been investigated in the semi-magic N=82 nucleus 140Ce using a novel combination of nuclear resonance fluorescence and γ–γ coincidence techniques. Branching ratios for transitions to low-lying excited states are determined in a direct and model-independent way both for individual excited states and for excitation energy intervals. Comparison of the experimental results to microscopic calculations in the quasi-particle phonon model exhibits an excellent agreement, supporting the observation that the Pygmy Dipole Resonance couples to the ground state as well as to low-lying excited states. A 10% mixing of the PDR and the [21+×PDR] is extracted. DA - 2016/5// PY - 2016/5// DO - 10.1016/J.PHYSLETB.2016.02.042 VL - 756 SP - 72-76 J2 - Physics Letters B LA - en OP - SN - 0370-2693 UR - http://dx.doi.org/10.1016/J.PHYSLETB.2016.02.042 DB - Crossref KW - gamma-ray spectroscopy KW - Ce-140 KW - Pygmy Dipole Resonance KW - Nuclear resonance fluorescence KW - Coincidence measurement KW - Quasi-particle phonon model ER - TY - JOUR TI - Energy Dependence of Fission Product Yields from 235U, 238U and 239Pu for Incident Neutron Energies Between 0.5 and 14.8 MeV AU - Gooden, M.E. AU - Arnold, C.W. AU - Becker, J.A. AU - Bhatia, C. AU - Bhike, M. AU - Bond, E.M. AU - Bredeweg, T.A. AU - Fallin, B. AU - Fowler, M.M. AU - Howell, C.R. AU - Kelley, J.H. AU - Krishichayan AU - Macri, R. AU - Rusev, G. AU - Ryan, C. AU - Sheets, S.A. AU - Stoyer, M.A. AU - Tonchev, A.P. AU - Tornow, W. AU - Vieira, D.J. AU - Wilhelmy, J.B. T2 - Nuclear Data Sheets AB - Fission Product Yields (FPY) have historically been one of the most observable features of the fission process. They are known to have strong variations that are dependent on the fissioning species, the excitation energy, and the angular momentum of the compound system. However, consistent and systematic studies of the variation of these FPY with energy have proved challenging. This is caused primarily by the nature of the experiments that have traditionally relied on radiochemical procedures to isolate specific fission products. Although radiochemical procedures exist that can isolate all products, each element presents specific challenges and introduces varying degrees of systematic errors that can make inter-comparison of FPY uncertain. Although of high importance in fields such as nuclear forensics and Stockpile Stewardship, accurate information about the energy dependence of neutron induced FPY are sparse, due primarily to the lack of suitable monoenergetic neutron sources. There is a clear need for improved data, and to address this issue, a collaboration was formed between Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL) and the Triangle Universities Nuclear Laboratory (TUNL) to measure the energy dependence of FPY for 235U, 238U and 239Pu. The measurements have been performed at TUNL, using a 10 MV Tandem Van de Graaff accelerator to produce monoenergetic neutrons at energies between 0.6 MeV to 14.8 MeV through a variety of reactions. The measurements have utilized a dual-fission chamber, with thin (10-100 μg/cm2) reference foils of similar material to a thick (100-400 mg) activation target held in the center between the chambers. This method allows for the accurate determination of the number of fissions that occurred in the thick target without requiring knowledge of the fission cross section or neutron fluence on target. Following activation, the thick target was removed from the dual-fission chamber and gamma-ray counted using shielded HPGe detectors for a period of 1-2 months to determine the yield of various fission products. To the extent possible all irradiation and counting procedures were kept the same to minimize sources of systematic errors. FPY have been determined at incident neutron energies of 0.6, 1.4, 2.4, 3.5, 4.6, 5.5, 8.9 and 14.8 MeV. DA - 2016/1// PY - 2016/1// DO - 10.1016/J.NDS.2015.12.006 VL - 131 SP - 319-356 J2 - Nuclear Data Sheets LA - en OP - SN - 0090-3752 UR - http://dx.doi.org/10.1016/J.NDS.2015.12.006 DB - Crossref ER - TY - JOUR TI - Local Anchorage of Kinetochore-Fibers to the Mammalian Spindle Provides Mechanical Isolation and Load-Bearing Redundancy AU - Elting, Mary W. AU - Udy, Dylan B. AU - Dumont, Sophie T2 - Biophysical Journal AB - During cell division, kinetochores attach chromosomes to the spindle through microtubule bundles called k-fibers. Forces generated at kinetochores move chromosomes, rather than k-fibers; thus, the latter must be structurally anchored to the spindle. How a dynamic spindle robustly anchors its k-fibers is not understood. Here, we probe where and how the mammalian spindle holds on to its k-fibers to bear the load of chromosome movement. We use laser ablation to sever k-fibers at different locations and detach them from spindle poles, thereby revealing their anchorage within the spindle body. The immediate relaxation response post-ablation indicates that k-fibers are anchored not only at their ends, but also along their lengths within the spindle. Effective anchorage scales with k-fiber length for the first few microns, but then saturates, indicating that k-fibers are effectively locally anchored within the first few microns of their lengths. This anchorage also occurs locally along the spindle's width, as little load is shared between neighboring k-fibers. We find that increasing microtubule crosslinking increases k-fiber anchorage, and that depleting NuMA, known to crosslink microtubules at poles, significantly disrupts local anchorage of k-fibers to the spindle body. In contrast, depletion of microtubule crosslinkers Eg5 and PRC1 does not affect anchorage despite these proteins’ local mechanical functions. Together, the data indicate that NuMA-mediated microtubule crosslinking in the spindle body allows for local anchorage and isolation of k-fibers, and mechanical redundancy in their connections to the spindle. Such mechanical isolation and redundancy are well-suited to ensure robust k-fiber load-bearing and chromosome segregation despite dynamic spindle forces and structures. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.1915 VL - 110 IS - 3 SP - 355a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.1915 DB - Crossref ER - TY - JOUR TI - Interactions of Antibacterial Peptides with Nanotubular Lipid Bilayers: Binding Kinetics and Distortions of the Bilayer Structure AU - Jafarabadi, Morteza AU - Marek, Antonin AU - Koolivand, Amir AU - Acharya, Biplav AU - Nevzorov, Alexander A. AU - Krim, Jacqueline AU - Smirnov, Alex I. T2 - Biophysical Journal AB - Interactions of peptides with membranes are central for understanding key cellular processes involving membrane proteins such as folding, signaling, transport, energy conversion, and immune response. These interactions also determine efficiency of antibacterial and cytotoxic peptides in disrupting the barrier function of cellular membranes. We employed macroscopically aligned tubular lipid bilayers confined inside cylindrical nanopores of anodic aluminum oxide (AAO) as a versatile nanotechnology platform to study membrane interactions of antibacterial peptides of melittin and alamecitin. Kinetics of peptide binding to lipid nanotubes and the eventual lipid removal/lysis (for melittin) were observed by quartz crystal microbalance (QCM) using a crystal with an in-house fabricated nanostructured surface while the structural changes in bilayers were monitored by solid state oriented sample NMR. Specifically, using 78 nm nanopores we have achieved exceptionally narrow (100-140 Hz or <1 ppm) 31P resonances of the lipid phosphate groups of macroscopically aligned nanotubular bilayers that indicated <1-2o mosaic spread in the lipid alignment in the absence of bioreactive peptides. 31P resonances broadened and shifted towards the isotropic values upon interacting with melittin with some lysis of lipids observed after several hours of exposure. The binding and lipid lysis from bilayers confined in essentially the same nanopores albeit at much smaller lipid quantity were further quantified by real-time QCM for bilayers of various lipid compositions. Taken together, the data relate peptide binding and lysis kinetics to structural changes in lipid bilayers, thus, shedding the light on the underlying multistep mechanism. The main advantage of the lipid nanotube AAO platform is in its versatile applicability to various biophysical methods such QCM and NMR under essentially the same environmental conditions such as pH, ionic strength, temperature, etc. and exceptionally broad range of lipid bilayer compositions. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.488 VL - 110 IS - 3 SP - 79a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.488 DB - Crossref ER - TY - JOUR TI - Stability and Ion Distributions Around Left- and Right-Handed DNA and RNA Duplexes: A Comparative Study AU - Pan, Feng AU - Man, Viet H. AU - Roland, Christopher AU - Sagui, Celeste T2 - Biophysical Journal AB - The determination of the relative stability of nucleic acids structures is often critical for the understanding of their molecular functions. Theoretically, the relative stability of polynucleotides is determined via free energy or thermal melting simulations. These quantities may, however, be computationally quite intensive and therefore challenging. As an interesting alternative, we explore the use of a non-equilibrium laser melting approach combined with molecular dynamics simulations in order to determine the relative stability of B-DNA and Z-DNA duplexes. Specifically, a fast laser pulse is applied to the d(5’-CGCGCGCGCGCG-3’)2 dodecamer in either form. A laser pulse, whose frequency is tuned to disrupt the Watson-Crick hydrogen bonds, is applied and induces a partial melting of the DNA duplexes. The subsequent structural relaxations and partial refolding is indicative of the greater stability of B-DNA in different aqueous environments. In addition, we have also carried out a detailed investigation of the ion atmosphere around both the B- and Z-DNA/RNA duplexes. This ion atmosphere is an intrinsic part of the structure of the solvated nucleic acids, but is difficult to probe experimentally. The ions investigated include Na+, K+, Mg2+, and Cl- in various concentrations. The simulations results quantitatively describe the characteristics of the ion distributions around the different nucleic acid structures. These, in turn, reflect the effect of the different ion types and the atomistic and structural elements of the nucleic acids, which are described and contrasted. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.2197 VL - 110 IS - 3 SP - 407a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.2197 DB - Crossref ER - TY - JOUR TI - Structural Determinants of Polyqlutamine Protofibrils and Crystallites AU - Man, Viet H. AU - Roland, Christopher AU - Sagui, Celeste T2 - Biophysical Journal AB - Nine inherited neurodegenerative diseases are associated with the expansion of the CAG codon. Once the translated polyglutamine expansion becomes longer than ∼36 residues, it triggers the formation of intraneural protein aggregates that often display the signature of cross-β amyloid fibrils. Here, we use fully atomistic molecular dynamics simulations with explicit solvent and state-of-the-art force field to probe the structural stability and conformational dynamics of both previously proposed and new polyglutamine aggregate models, for a cumulative time of over 23 μs. We estimate the relative stability of parallel and antiparallel β sheets, and characterize possible steric interfaces between neighboring sheets and the effects of different alignments of the side-chain carboxamide dipoles. The results indicate that (i) different initial oligomer structures converge to crystals consistent with available diffraction data, after undergoing cooperative side-chain rotational transitions and quarter-stagger displacements on a microsecond time scale, (ii) structures previously deemed stable on a hundred nanosecond time scale are unstable over the microsecond time scale, and (iii) conversely, structures previously deemed unstable did not account for the correct side-chain packing and once the correct symmetry is considered the structures become stable for over a microsecond, due to tightly interdigitated side chains, which lock into highly regular polar zippers with inter-side-chain and backbone−side-chain hydrogen bonds. With these insights, we built Q40 monomeric models with different combinations of arc and hairpin turns and tested them for stability. The stable monomers were further probed as a function of repeat length. Our results are consistent with the aggregation threshold. These results explain and reconcile previously reported experimental and model discrepancies about polyglutamine aggregate structures. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.1192 VL - 110 IS - 3 SP - 215a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.1192 DB - Crossref ER - TY - JOUR TI - Contrasting Roles of Asparagine and Glutamine in the Aggregation of Prion-Like Proteins AU - Zhang, Yuan AU - Hoang Man, Viet AU - Roland, Christopher AU - Sagui, Celeste T2 - Biophysical Journal AB - Sequences rich in glutamine (Q) and asparagine (N) are intrinsically disordered in monomeric form, but can aggregate into highly ordered amyloids, as seen in Q/N-rich prion domains (PrDs). Amyloids are fibrillar protein aggregates rich in β-sheet structures that can self-propagate through protein-conformational chain reactions. It has been shown that tuning the amount of Ns and Qs in yeast PrDs results in very different effects: N-rich mutants lead to non-pathological self-seeding amyloids while Q-rich mutants lead to toxic nonamyloid structures. These structural preferences have been explained in terms of an enhanced β- hairpin turn propensity of Ns over Qs. Here, we consider a variety of N/Q-rich peptides, including sequences found in the yeast Sup35 PrD, in parallel and antiparallel β-sheet aggregates, and probe all their possible steric-zipper interfaces to determine their relative stability. Our results show that polyglutamine aggregates are more stable than polyasparagine aggregates. The observation that Q-rich PrD mutants lack amyloid structure can be attributed to three facts. First, although once formed polyglutamine aggregates are more stable, their entropic contribution to the free energy is less favorable: Q-rich sequences have a larger phase space to sample. Second, N-rich sequences favor parallel β sheets, for which the formation of hairpin turns is irrelevant: indeed polyasparagine β-hairpins are more unstable than polyglutamine hairpins. Third, when other amino acids are present, such as in the Sup35 PrD, their shorter side chains favor steric-zipper formation for N but not Q, as they preclude the in-register association of the long Q side chains. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.1191 VL - 110 IS - 3 SP - 214a-215a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.1191 DB - Crossref ER - TY - JOUR TI - Designing ternary blend bulk heterojunction solar cells with reduced carrier recombination and a fill factor of 77% AU - Gasparini, Nicola AU - Jiao, Xuechen AU - Heumueller, Thomas AU - Baran, Derya AU - Matt, Gebhard J. AU - Fladischer, Stefanie AU - Spiecker, Erdmann AU - Ade, Harald AU - Brabec, Christoph J. AU - Ameri, Tayebeh T2 - Nature Energy DA - 2016/8/22/ PY - 2016/8/22/ DO - 10.1038/NENERGY.2016.118 VL - 1 IS - 9 J2 - Nat Energy LA - en OP - SN - 2058-7546 UR - http://dx.doi.org/10.1038/NENERGY.2016.118 DB - Crossref ER - TY - JOUR TI - smFRET and DEER Distance Measurements as Applied to Disordered and Structured Proteins AU - Weninger, Keith AU - Qiu, Ruoyi AU - Ou, Erkang AU - Milikisiyants, Sergey AU - Sanabria, Hugo AU - Smirnova, Tatyana I. T2 - Biophysical Journal AB - FRET and DEER are two spectroscopic methods that are widely applied for biophysical studies of protein structure. Both methods are based on measuring dipolar interactions - electrical dipoles in case of FRET and magnetic dipoles in case of DEER - between specifically labeled protein sites. The experimental data are then analyzed to derive the distance between the interacting dipoles and relate this distance to the structure of biomacromolecule(s). Molecular volume of EPR labels is generally smaller vs. that of the fluorescent probes and DEER experiments can be carried out by labeling cysteines with identical molecular tags whereas FRET typically relies on orthogonal labeling with distinct donor and acceptor fluorophores. Another essential difference is that FRET can be performed under physiological conditions, but DEER typically requires cryogenic or near cryogenic temperatures because of short phase memory time for nitroxides at ambient conditions. Finally, single molecule (sm) FRET reports on conformation of individual protein molecules whereas DEER provides information on ensemble average. While the distance ranges of these two methods overlaps the direct comparison of FRET and DEER data is rarely found in the literature. Here we report on the distance measurements and conformational states using both smFRET and DEER on three protein systems. We attached probes to a unique pair of cysteines in the neuronal SNARE protein SNAP-25. SNAP-25 is highly disordered in isolation, but it folds into a stable alpha-helix bundle upon forming SNARE complex with syntaxin and synaptobrevin. We also labeled intrinsically disordered Glutamate Receptor Cytoplasmic Domain N2B. Results of smFRET and DEER distances and distance distribution are compared for disordered SNAP-25 and folded SNAP-25 within the SNARE complex and for disordered N2B. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.2987 VL - 110 IS - 3 SP - 559a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.2987 DB - Crossref ER - TY - JOUR TI - tN-Ras, Synaptotagmin1 C2Ab, Annexinb12 and Amphiphysin NBAR can Discriminate Spherical from Cylindrical Membrane Curvature AU - Breuer, Artu' AU - Larsen, Jannik AU - Røskva Rosholm, Kadla AU - Pedersenb, Søren L. AU - Munch, Henrik K. AU - Tkach, Vadym AU - Sakon, John J. AU - Bjørnholm, Thomas AU - Weninger, Keith R. AU - Bendix, Poul M. AU - Jensen, Knud J. AU - Uline, Mark J. AU - Hatzakis, Nikos S. AU - Stamou, Dimitrios T2 - Biophysical Journal AB - Membrane shape or geometrical curvature emerged recently as a potent regulator of membrane recruitment during protein trafficking and sorting. Cellular membranes display distinct curvature geometries e.g. spherical (trafficking- and synaptic vesicles) or cylindrical (tubes in the ER and Golgi), however quantitative studies of protein recruitment by membrane curvature typically focus on a single geometry. Thus the biological implications of different curvature geometries remain largely unexplored. We recently used our single liposome assay to show that the N-Ras lipid anchor (tN-Ras) is recruited by spherical membrane curvature. Here we report the development of a novel membrane tube assay, allowing us to quantitatively compare the recruitment of tN-Ras by spherical and cylindrical membrane curvature. Furthermore we expand the study to include representatives of the four most common families of membrane-binding domains (MBDs); the lipid anchor of N-Ras (tN-Ras), the C2AB-domain of Synaptotagmin1 (Syt), AnnexinB12 (Anx) and Amphiphysin NBAR (Amph). Our data revealed an increased recruitment of all four MBDs by spherical as compared to cylindrical curvature. Molecular field theory calculations attributed this trend to the greater perturbation of lipid packing parameters by spherically curved membranes. Importantly, the four MBDs displayed markedly distinct abilities to discriminate the two curvature geometries e.g. tN-Ras had a moderate 2-fold discrimination while Amph a remarkable absolute preference for spherical membranes. This demonstrated that discrimination of curvature geometry can be modulated and likely adapted to specific biological functions. Our results reveal membrane curvature geometry as a novel regulator of protein recruitment during trafficking and sorting for a plethora of membrane-binding proteins, and thus suggest a novel functional role to the diversity of conserved organelle morphologies. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.1924 VL - 110 IS - 3 SP - 357a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.1924 DB - Crossref ER - TY - JOUR TI - Venoms from Centruroides sp. Scorpions Cleave SNARE Proteins AU - Fletcher, Paul L., Jr. AU - Fletcher, Maryann D. AU - Weninger, Keith R. AU - Martin, Brian M. T2 - Toxicon DA - 2016/7// PY - 2016/7// DO - 10.1016/J.TOXICON.2016.04.025 VL - 117 SP - 109 J2 - Toxicon LA - en OP - SN - 0041-0101 UR - http://dx.doi.org/10.1016/J.TOXICON.2016.04.025 DB - Crossref ER - TY - JOUR TI - “Metalloproteases in new world scorpion venoms cleave intracellular membrane fusion SNARE proteins VAMP2 and VAMP8” AU - Fletcher, Paul L., Jr. AU - Fletcher, Maryann D. AU - Weninger, Keith R. T2 - Toxicon DA - 2016/7// PY - 2016/7// DO - 10.1016/J.TOXICON.2016.04.008 VL - 117 SP - 104 J2 - Toxicon LA - en OP - SN - 0041-0101 UR - http://dx.doi.org/10.1016/J.TOXICON.2016.04.008 DB - Crossref ER - TY - JOUR TI - Light-Front Quark Model Phenomenology Consistent with Chiral Symmetry AU - Choi, Ho-Meoyng AU - Ji, Chueng-Ryong T2 - EPJ Web of Conferences AB - We discuss the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the twist-2 and twist-3 distribution amplitudes of a pion. In particular, we exhibit that the pion twist-3 distribution amplitude can flip the sign of curvature as the cutoff scale for the transverse momentum gets lower than a typical scale of around 1 GeV. DA - 2016/// PY - 2016/// DO - 10.1051/EPJCONF/201611305009 VL - 113 SP - 05009 J2 - EPJ Web of Conferences OP - SN - 2100-014X UR - http://dx.doi.org/10.1051/EPJCONF/201611305009 DB - Crossref ER - TY - JOUR TI - The Construction of Compton Tensors in Scalar QED AU - Bakker, Bernard L. G. AU - Ji, Chueng-Ryong T2 - Few-Body Systems AB - Current conservation is a vital condition in electrodynamics. We review the literature concerning the ways to ensure that the formalism used in calculating amplitudes for the scattering of charged particles is in compliance with current conservation. For the case of electron scattering off a scalar and a spin-1/2 target as well as Compton scattering on a scalar target, we present some novelties besides reviewing the literature. DA - 2016/12/9/ PY - 2016/12/9/ DO - 10.1007/S00601-016-1172-3 VL - 58 IS - 1 J2 - Few-Body Syst LA - en OP - SN - 0177-7963 1432-5411 UR - http://dx.doi.org/10.1007/S00601-016-1172-3 DB - Crossref ER - TY - JOUR TI - Efficient Generation of Long-Lived Triplet Excitons in 2D Hybrid Perovskite AU - Younts, Robert AU - Duan, Hsin-Sheng AU - Gautam, Bhoj AU - Saparov, Bayrammurad AU - Liu, Jie AU - Mongin, Cedric AU - Castellano, Felix N. AU - Mitzi, David B. AU - Gundogdu, Kenan T2 - Advanced Materials AB - Triplet excitons form in quasi-2D hybrid inorganic-organic perovskites and diffuse over 100 nm before radiating with >11% photoluminescence quantum efficiency (PLQE) at low temperatures. DA - 2016/12/23/ PY - 2016/12/23/ DO - 10.1002/ADMA.201604278 VL - 29 IS - 9 SP - 1604278 J2 - Adv. Mater. LA - en OP - SN - 0935-9648 UR - http://dx.doi.org/10.1002/ADMA.201604278 DB - Crossref ER - TY - JOUR TI - Dynamics of Large DNA Loops AU - Azad, Zubair AU - Riehn, Robert T2 - Biophysical Journal AB - Dynamics of Large DNA Loops Long range interactions between genetically distant regions of DNA (>10 kbp) are not governed by the elastic energies of bending and twisting of DNA, but rather by entropic forces. Furthermore, such large scale interactions are mediated strongly by the excluded volume interactions of DNA and proteins of the cellular environment. It is not clear how these interactions locally couple to variables such as temperature, salt strength, pH, etc. in nanoconfined volumes where the monomer density of DNA is comparable to that in the cell nucleus. Using a nanofluidic device, we manipulate fluid flow to drive DNA into large loops, on the order of kilobasepairs, in a range of buffer concentrations and protein backgrounds. By analyzing the dynamics of the loop formation, steady state fluctuations, and deformation, we quantify an energy landscape. We can use this energy landscape to characterize activation barriers for proteins to form DNA loops. Once these activation barriers are overcome, we can test for enhancements in the loop elongation rate due to proteins. In addition, we can test for arrested states caused by proteins binding to specific sequences. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.BPJ.2015.11.3023 VL - 110 IS - 3 SP - 565a J2 - Biophysical Journal LA - en OP - SN - 0006-3495 UR - http://dx.doi.org/10.1016/J.BPJ.2015.11.3023 DB - Crossref ER - TY - CONF TI - Lefschetz-thimble approach to the Silver Blaze problem of one-site fermion model AU - Tanizaki, Yuya AU - Hidaka, Yoshimasa AU - Hayata, Tomoya AB - The sign problem of finite-density QCD at the zero temperature becomes very severe if the quark chemical potential exceeds half of the pion mass. In order to understand its property, we consider the sign problem of the one-site fermion model appearing in its path-integral expression by using the Lefschetz-thimble method. We show that the original integration cycle becomes decomposed into multiple Lefschetz thimbles at a certain value of the fermion chemical potential, which would correspond to half of the pion mass of finite-density QCD. This triggers a fictitious phase transition on each Lefschetz thimble, and the interference of complex phases among them plays an important role for the correct description of the system. We also show that the complex Langevin method does not work in this situation. C2 - 2016/9/26/ C3 - PoS CY - Southampton, United Kingdom DA - 2016/9/26/ DO - 10.22323/1.256.0030 VL - LATTICE2016 SP - 030 PB - SISSA UR - http://inspirehep.net/record/1489199 ER - TY - JOUR TI - Lefschetz-thimble analysis of the sign problem in one-site fermion model AU - Tanizaki, Yuya AU - Hidaka, Yoshimasa AU - Hayata, Tomoya T2 - New J.Phys. AB - The Lefschetz-thimble approach to path integrals is applied to a one-site model of electrons, i.e., the one-site Hubbard model. Since the one-site Hubbard model shows a non-analytic behavior at the zero temperature and its path integral expression has the sign problem, this toy model is a good testing ground for an idea or a technique to attack the sign problem. Semiclassical analysis using complex saddle points unveils the significance of interference among multiple Lefschetz thimbles to reproduce the non-analytic behavior by using the path integral. If the number of Lefschetz thimbles is insufficient, we found not only large discrepancies from the exact result, but also thermodynamic instabilities. Analyzing such singular behaviors semiclassically, we propose a criterion to identify the necessary number of Lefschetz thimbles. We argue that this interference of multiple saddle points is a key issue to understand the sign problem of the finite-density quantum chromodynamics. DA - 2016/3/1/ PY - 2016/3/1/ DO - 10.1088/1367-2630/18/3/033002 VL - 18 IS - 3 SP - 033002 UR - http://inspirehep.net/record/1394683 KW - sign problem KW - semiclassical analysis KW - Lefschetz thimbles KW - Lee-Yang zeros ER - TY - JOUR TI - Complex saddle points and the sign problem in complex Langevin simulation AU - Hayata, Tomoya AU - Hidaka, Yoshimasa AU - Tanizaki, Yuya T2 - Nucl.Phys.B AB - We show that complex Langevin simulation converges to a wrong result within the semiclassical analysis, by relating it to the Lefschetz-thimble path integral, when the path-integral weight has different phases among dominant complex saddle points. Equilibrium solution of the complex Langevin equation forms local distributions around complex saddle points. Its ensemble average approximately becomes a direct sum of the average in each local distribution, where relative phases among them are dropped. We propose that by taking these phases into account through reweighting, we can solve the wrong convergence problem. However, this prescription may lead to a recurrence of the sign problem in the complex Langevin method for quantum many-body systems. DA - 2016/10// PY - 2016/10// DO - 10.1016/j.nuclphysb.2016.07.031 VL - 911 SP - 94-105 UR - http://inspirehep.net/record/1403563 ER - TY - JOUR TI - Simple nonlinear models suggest variable star universality AU - Lindner, John F. AU - Kohar, Vivek AU - Kia, Behnam AU - Hippke, Michael AU - Learned, John G. AU - Ditto, William L. T2 - Physica D: Nonlinear Phenomena AB - Dramatically improved data from observatories like the CoRoT and Kepler spacecraft have recently facilitated nonlinear time series analysis and phenomenological modeling of variable stars, including the search for strange (aka fractal) or chaotic dynamics. We recently argued [Lindner et al., Phys. Rev. Lett. 114 (2015) 054101] that the Kepler data includes “golden” stars, whose luminosities vary quasiperiodically with two frequencies nearly in the golden ratio, and whose secondary frequencies exhibit power-law scaling with exponent near −1.5, suggesting strange nonchaotic dynamics and singular spectra. Here we use a series of phenomenological models to make plausible the connection between golden stars and fractal spectra. We thereby suggest that at least some features of variable star dynamics reflect universal nonlinear phenomena common to even simple systems. DA - 2016/2// PY - 2016/2// DO - 10.1016/J.PHYSD.2015.10.006 VL - 316 SP - 16-22 J2 - Physica D: Nonlinear Phenomena LA - en OP - SN - 0167-2789 UR - http://dx.doi.org/10.1016/J.PHYSD.2015.10.006 DB - Crossref KW - Nonlinear dynamics KW - Variable stars KW - Golden ratio KW - Universality ER - TY - JOUR TI - Supernova Physics at DUNE DA - 2016/8/28/ PY - 2016/8/28/ ER - TY - JOUR TI - Get a room: the role of classroom space in sustained implementation of studio style instruction AU - Knaub, Alexis V. AU - Foote, Kathleen T. AU - Henderson, Charles AU - Dancy, Melissa AU - Beichner, Robert J. T2 - International Journal of STEM Education AB - The characteristics of the classroom environment play an important role in shaping teaching practices and supporting research-based instructional strategies. One instructional strategy that has reimagined the classroom is the Student-Centered Active Learning Environment with Upside-Down Pedagogies (SCALE-UP). SCALE-UP uses studio-style instruction to facilitate student collaboration. Although there is significant interest in studio-style instruction, there is not much research-based guidance available for institutions interested in setting up a classroom, especially for secondary users interested in using this in different academic settings and contexts. We interviewed key informants involved in 21 successful secondary implementations of SCALE-UP about creating, using, and spreading studio-style classrooms. This paper summarizes respondent’s perceptions of (1) how these classrooms are initiated; (2) which classroom features are helpful, non-essential, and unhelpful; (3) how professional development efforts support SCALE-UP instructors; and (4) how the classroom indirectly affects the department and/or institution. Room initiation Interviewees engaged in multiple activities to obtain a studio-style classroom. The majority of interviewees worked in teams created by faculty or administrators, with the participation from both groups. Interviewees typically sought institutional funding to develop the rooms. Classroom features When developing the room, implementers used many key characteristics of the recommended classroom, such as collaborative workspace (e.g., special tables) for students, but they generally did not replicate all of the recommended features. Interviewees had mixed opinions about the importance of classroom technology. Professional development and support Interviewees noted the importance of professional development for teaching staff (instructors and teaching assistants) new to the SCALE-UP teaching environment. Indirect effects Beyond direct benefits to the teachers and learners, our interviewees reported that the classrooms had larger impacts including attracting visitors to the institution and encouraging the use of active learning in non-SCALE-UP classes. There are many paths to successful development of a studio-style classroom. The process can be initiated by faculty or administrators. Classroom designs can vary to suit the local environment as long as they maintain the intent of the space: to support peer collaboration. Beyond improving student outcomes, these classrooms have additional benefits for institutions that include transforming instructor approaches to teaching and symbolizing the institution’s commitment to quality teaching. DA - 2016/5/5/ PY - 2016/5/5/ DO - 10.1186/s40594-016-0042-3 VL - 3 IS - 1 J2 - IJ STEM Ed LA - en OP - SN - 2196-7822 UR - http://dx.doi.org/10.1186/s40594-016-0042-3 DB - Crossref KW - SCALE-UP KW - Studio-style instruction KW - Classroom design KW - Modifying education innovation KW - Active learning spaces ER - TY - JOUR TI - Electrically Coupling Multifunctional Oxides to Semiconductors: A Route to Novel Material Functionalities AU - Ngai, J. H. AU - Ahmadi-Majlan, K. AU - Moghadam, J. AU - Chrysler, M. AU - Kumah, D. P. AU - Ahn, C. H. AU - Walker, F. J. AU - Droubay, T. AU - Bowden, M. AU - Chambers, S. A. AU - Shen, X. AU - Su, D. T2 - MRS Advances DA - 2016/// PY - 2016/// DO - 10.1557/adv.2016.101 VL - 1 IS - 4 SP - 255-263 J2 - MRS Adv. LA - en OP - SN - 2059-8521 UR - http://dx.doi.org/10.1557/adv.2016.101 DB - Crossref ER - TY - JOUR TI - Engineered Unique Elastic Modes at a BaTiO3/(2×1)−Ge(001) Interface AU - Kumah, D.P. AU - Dogan, M. AU - Ngai, J. H. AU - Qiu, D. AU - Zhang, Z. AU - Su, D. AU - Specht, E. D. AU - Ismail-Beigi, S. AU - Ahn, C. H. AU - Walker, F. J. AU - al. T2 - Physical Review Letters AB - The strong interaction at an interface between a substrate and thin film leads to epitaxy and provides a means of inducing structural changes in the epitaxial film. These induced material phases often exhibit technologically relevant electronic, magnetic, and functional properties. The 2×1 surface of a Ge(001) substrate applies a unique type of epitaxial constraint on thin films of the perovskite oxide BaTiO_{3} where a change in bonding and symmetry at the interface leads to a non-bulk-like crystal structure of the BaTiO_{3}. While the complex crystal structure is predicted using first-principles theory, it is further shown that the details of the structure are a consequence of hidden phases found in the bulk elastic response of the BaTiO_{3} induced by the symmetry of forces exerted by the germanium substrate. DA - 2016/3/7/ PY - 2016/3/7/ DO - 10.1103/physrevlett.116.106101 VL - 116 IS - 10 SN - 0031-9007 1079-7114 UR - http://dx.doi.org/10.1103/physrevlett.116.106101 ER - TY - JOUR TI - Role of double TiO2 layers at the interface of FeSe/SrTiO3 superconductors AU - Zou, Ke AU - Mandal, Subhasish AU - Albright, Stephen D. AU - Peng, Rui AU - Pu, Yujia AU - Kumah, Divine AU - Lau, Claudia AU - Simon, Georg H. AU - Dagdeviren, Omur E. AU - He, Xi AU - Božović, Ivan AU - Schwarz, Udo D. AU - Altman, Eric I. AU - Feng, Donglai AU - Walker, Fred J. AU - Ismail-Beigi, Sohrab AU - Ahn, Charles H. T2 - Physical Review B AB - We determine the surface reconstruction of SrTiO3 used to achieve superconducting FeSe films in experiments, which is different from the 1x1 TiO2 terminated SrTiO3 assumed by most previous theoretical studies. In particular, we identify the existence of a double TiO2 layer at the SrTiO3-FeSe interface that plays two important roles. First, it facilitates the epitaxial growth of FeSe. Second, ab initio calculations reveal a strong tendency for electrons to transfer from an oxygen deficient SrTiO3 surface to FeSe when the double TiO2 layer is present. As a better electron donor than previously proposed interfacial structures, the double layer helps to remove the hole pocket in the FeSe at the {\Gamma} point of the Brillouin zone and leads to a band structure characteristic of superconducting samples. The characterization of the interface structure presented here is a key step towards the resolution of many open questions about this novel superconductor. DA - 2016/5/16/ PY - 2016/5/16/ DO - 10.1103/physrevb.93.180506 VL - 93 IS - 18 SN - 2469-9950 2469-9969 UR - http://dx.doi.org/10.1103/physrevb.93.180506 ER - TY - MANSCPT TI - White Paper on Nuclear Astrophysics AU - Arcones, Almudena AU - Bardayan, Dan W. AU - Beers, Timothy C. AU - Berstein, Lee A. AU - Blackmon, Jeffrey C. AU - Messer, Bronson AU - Brown, B. Alex AU - Brown, Edward F. AU - Brune, Carl R. AU - Champagne, Art E. AU - Chieffi, Alessandro AU - Couture, Aaron J. AU - Danielewicz, Pawel AU - Diehl, Roland AU - El-Eid, Mounib AU - Escher, Jutta AU - Fields, Brian D. AU - Fröhlich, Carla AU - Herwig, Falk AU - Hix, William Raphael AU - Iliadis, Christian AU - Lynch, William G. AU - McLaughlin, Gail C. AU - Meyer, Bradley S. AU - Mezzacappa, Anthony AU - Nunes, Filomena AU - Brian W. O'Shea, AU - Prakash, Madappa AU - Pritychenko, Boris AU - Reddy, Sanjay AU - Rehm, Ernst AU - Rogachev, Grigory AU - Rutledge, Robert E. AU - Schatz, Hendrik AU - Smith, Michael S. AU - Stairs, Ingrid H. AU - Steiner, Andrew W. AU - Strohmayer, Tod E. AU - Timmes, Frank X. AU - Townsley, Dean M. AU - Wiescher, Michael AU - Zegers, Remco G. T. AU - Zingale, Michael DA - 2016/3// PY - 2016/3// ER - TY - RPRT TI - Energy Flow in Dense Off-Equilibrium Plasma AU - Putterman, Seth AU - Bataller, Alex AU - Koulakis, John AU - Pree, Seth AU - Latshaw, Alexandra A3 - University of California, Los Angeles Los Angeles United States DA - 2016/// PY - 2016/// PB - University of California, Los Angeles Los Angeles United States ER - TY - JOUR TI - Comment on “Early stage time evolution of a dense nanosecond microdischarge used in fast optical switching applications”[Phys. Plasmas 22, 123518 (2015)] AU - Bataller, A AU - Koulakis, J AU - Pree, S AU - Putterman, S T2 - Physics of Plasmas DA - 2016/// PY - 2016/// VL - 23 IS - 3 SP - 034705 ER - TY - CONF TI - The Kinematics of the Milky Way's Biconical Nuclear Wind AU - Fox, Andrew AU - Bordoloi, Rongmon AU - Jenkins, Edward B AU - Savage, Blair D AU - Hernandez, Svea AU - Wakker, Bart P AU - Bland-Hawthorn, Jonathan AU - Lockman, Felix J AU - Tumlinson, Jason C2 - 2016/// C3 - American Astronomical Society Meeting Abstracts# 227 DA - 2016/// VL - 227 ER - TY - CONF TI - A Deep Search for Galaxies Associated With Very Low-redshift Metal-line Absorbers: The Circumgalactic Media of Dwarf Galaxies and Environmental Effects AU - Burchett, Joseph AU - Tripp, Todd M AU - Bordoloi, Rongmon AU - Willmer, Christopher C2 - 2016/// C3 - American Astronomical Society Meeting Abstracts# 227 DA - 2016/// VL - 227 ER - TY - JOUR TI - A Deep Search for Faint Galaxies Associated with Very Low Redshift C IV Absorbers. III. The Mass-and Environment-dependent Circumgalactic Medium AU - Burchett, Joseph N AU - Tripp, Todd M AU - Bordoloi, Rongmon AU - Werk, Jessica K AU - Prochaska, J Xavier AU - Tumlinson, Jason AU - Willmer, CNA AU - O’Meara, John AU - Katz, Neal T2 - The Astrophysical Journal DA - 2016/// PY - 2016/// VL - 832 IS - 2 SP - 124 ER - TY - JOUR TI - The Properties of the Circumgalactic Medium in Red and Blue Galaxies: Results from the COS-GASS+ COS-Halos Surveys AU - Borthakur, Sanchayeeta AU - Heckman, Timothy AU - Tumlinson, Jason AU - Bordoloi, Rongmon AU - Kauffmann, Guinevere AU - Catinella, Barbara AU - Schiminovich, David AU - Davé, Romeel AU - Moran, Sean M AU - Saintonge, Amelie T2 - The Astrophysical Journal DA - 2016/// PY - 2016/// VL - 833 IS - 2 SP - 259 ER - TY - CONF TI - The GMOX science case: resolving galaxies through cosmic time AU - Gennaro, Mario AU - Robberto, Massimo AU - Heckman, Timothy AU - Smee, Stephen A AU - Barkhouser, Robert AU - Ninkov, Zoran AU - Adamo, Angela AU - Becker, George AU - Bellini, Andrea AU - Bianchi, Luciana AU - others T2 - International Society for Optics and Photonics C2 - 2016/// C3 - Ground-based and Airborne Instrumentation for Astronomy VI DA - 2016/// VL - 9908 SP - 990849 ER - TY - JOUR TI - The First Distance Constraint on the Renegade High-velocity Cloud Complex WD AU - Peek, JEG AU - Bordoloi, Rongmon AU - Sana, Hugues AU - Roman-Duval, Julia AU - Tumlinson, Jason AU - Zheng, Yong T2 - The Astrophysical Journal Letters DA - 2016/// PY - 2016/// VL - 828 IS - 2 SP - L20 ER - TY - JOUR TI - VizieR Online Data Catalog: z< 0.16 CIV absorbers from HST/COS QSOs spectra (Burchett+, 2015) AU - Burchett, JN AU - Tripp, TM AU - Prochaska, JX AU - Werk, JK AU - Tumlinson, J AU - O’Meara, JM AU - Bordoloi, R AU - Katz, N AU - Willmer, CNA T2 - VizieR Online Data Catalog DA - 2016/// PY - 2016/// VL - 181 ER - TY - JOUR TI - Spatially resolved galactic wind in lensed galaxy RCSGA 032727-132609 AU - Bordoloi, Rongmon AU - Rigby, Jane R AU - Tumlinson, Jason AU - Bayliss, Matthew B AU - Sharon, Keren AU - Gladders, Michael G AU - Wuyts, Eva T2 - Monthly Notices of the Royal Astronomical Society DA - 2016/// PY - 2016/// VL - 458 IS - 2 SP - 1891-1908 ER - TY - JOUR TI - Baryon cycling in the low-redshift circumgalactic medium: a comparison of simulations to the COS-Halos survey AU - Ford, Amanda Brady AU - Werk, Jessica K AU - Davé, Romeel AU - Tumlinson, Jason AU - Bordoloi, Rongmon AU - Katz, Neal AU - Kollmeier, Juna A AU - Oppenheimer, Benjamin D AU - Peeples, Molly S AU - Prochaska, Jason X AU - others T2 - Monthly Notices of the Royal Astronomical Society DA - 2016/// PY - 2016/// VL - 459 IS - 2 SP - 1745-1763 ER - TY - JOUR TI - The20Ne(d,p)21Ne transfer reaction in relation to thes-process abundances AU - Nsangu, C T AU - Laird, A M AU - Parikh, A AU - Adsley, P AU - Birch, M D AU - Chen, A A AU - Faestermann, T AU - Fox, S P AU - Fulton, B R AU - Hertenberger, R AU - Irvine, D AU - Kay, B P AU - Longland, R AU - Manwell, S AU - Murphy, A St J AU - Schmitt, K AU - Séréville, N AU - Tomlinson, J R AU - Wirth, H-F T2 - Journal of Physics: Conference Series AB - A study of the 20Ne(d,p)21Ne transfer reaction was performed using the Quadrupole Dipole Dipole Dipole (Q3D) magnetic spectrograph in Garching, Germany. The experiment probed excitation energies in 21Ne ranging from 6.9 MeV to 8.5 MeV. The aim was to investigate the spectroscopic information of 21Ne within the Gamow window of core helium burning in massive stars. Further information in this region will help reduce the uncertainties on the extrapolation down to Gamow window cross sections of the 17O(α,γ)21Ne reaction. In low metallicity stars, this reaction has a direct impact on s-process abundances by determining the fate of 16O as either a neutron poison or a neutron absorber. DA - 2016/1/5/ PY - 2016/1/5/ DO - 10.1088/1742-6596/665/1/012026 VL - 665 SP - 012026 ER - TY - JOUR TI - Measurement of very low (α,n) cross sections of astrophysical interest AU - Tain, J L AU - Jordán, D AU - Agramunt, J AU - Algora, A AU - Bandac, I AU - Bettini, A AU - Caballero-Folch, R AU - Calviño, F AU - Cano-Ott, D AU - Cortés, G AU - Domingo-Pardo, C AU - Fraile, L M AU - García, A R AU - Gomez-Cadenas, J J AU - José, J AU - Longland, R AU - Mendoza, E AU - Parikh, A T2 - Journal of Physics: Conference Series AB - The reactions C-13(alpha,n)O-16 and Ne-22(alpha,n)Mg-25 are the primary sources of neutrons for the astrophysical s-process. The feasibility of cross section measurements within the respective Gamow windows is discussed in quantitative terms for a 4 pi neutron counter, based on He-3 tubes and a neutron moderator, placed in an underground lab. DA - 2016/1/5/ PY - 2016/1/5/ DO - 10.1088/1742-6596/665/1/012031 VL - 665 SP - 012031 ER - TY - JOUR TI - New Polymer Donors for Polymer Solar Cells T2 - POLYMER PHOTOVOLTAICS: MATERIALS, PHYSICS, AND DEVICE ENGINEERING DA - 2016/// PY - 2016/// UR - https://publons.com/wos-op/publon/7528283/ ER - TY - JOUR TI - Panchromatic Sequentially Cast Ternary Polymer Solar Cells AU - Ghasemi, M. AU - Ye, L. AU - Zhang, Q. AU - Yan, L. AU - Kim, J.-H. AU - Awartani, O. AU - You, W. AU - Gadisa, A. AU - Ade, H. T2 - Advanced Materials AB - A sequential-casting ternary method is developed to create stratified bulk heterojunction (BHJ) solar cells, in which the two BHJ layers are spin cast sequentially without the need of adopting a middle electrode and orthogonal solvents. This method is found to be particularly useful for polymers that form a mechanically alloyed morphology due to the high degree of miscibility in the blend. DA - 2016/// PY - 2016/// DO - 10.1002/adma.201604603 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85006265334&partnerID=MN8TOARS ER - TY - JOUR TI - Molecular Design of Benzodithiophene-Based Organic Photovoltaic Materials. AU - Yao, Huifeng AU - Ye, Long AU - Zhang, Hao AU - Li, Sunsun AU - Zhang, Shaoqing AU - Hou, Jianhui T2 - Chemical reviews AB - Advances in the design and application of highly efficient conjugated polymers and small molecules over the past years have enabled the rapid progress in the development of organic photovoltaic (OPV) technology as a promising alternative to conventional solar cells. Among the numerous OPV materials, benzodithiophene (BDT)-based polymers and small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking 10% efficiency barrier in the single junction OPV devices. Remarkably, the OPV device featured by BDT-based polymer has recently demonstrated an impressive PCE of 11.21%, indicating the great potential of this class of materials in commercial photovoltaic applications. In this review, we offered an overview of the organic photovoltaic materials based on BDT from the aspects of backbones, functional groups, alkyl chains, and device performance, trying to provide a guideline about the structure-performance relationship. We believe more exciting BDT-based photovoltaic materials and devices will be developed in the near future. DA - 2016/// PY - 2016/// DO - 10.1021/acs.chemrev.6b00176 VL - 116 IS - 12 SP - 7397-457 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:27251307&KeyUID=MEDLINE:27251307 ER - TY - JOUR TI - Green-solvent-processable organic solar cells AU - Zhang, S. AU - Ye, L. AU - Zhang, H. AU - Hou, J. T2 - Materials Today AB - Solution-processable organic photovoltaics (OPV) has emerged as a promising clean energy-generating technology due to its potential for low-cost manufacturing with a high power/weight ratio. The state-of-the-art OPV devices are processed by hazardous halogenated solvents. Fabricating high-efficiency OPV devices using greener solvents is a necessary step toward their eventual commercialization. In this review, recent research efforts and advances in green-solvent-processable OPVs are summarized, and two basic strategies including material design and solvent selection of light-harvesting layers are discussed. In particular, the most recent green-solvent-processable OPVs with high efficiencies in excess of 9% are highlighted. DA - 2016/// PY - 2016/// DO - 10.1016/j.mattod.2016.02.019 VL - 19 IS - 9 SP - 533-543 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84961223535&partnerID=MN8TOARS ER - TY - JOUR TI - High-Efficiency Nonfullerene Organic Solar Cells: Critical Factors that Affect Complex Multi-Length Scale Morphology and Device Performance AU - Ye, L. AU - Zhao, W. AU - Li, S. AU - Mukherjee, S. AU - Carpenter, J.H. AU - Awartani, O. AU - Jiao, X. AU - Hou, J. AU - Ade, H. T2 - Advanced Energy Materials AB - Organic solar cells (OSCs) made of donor/acceptor bulk‐heterojunction active layers have been of widespread interest in converting sunlight to electricity. Characterizing of the complex morphology at multiple length scales of polymer:nonfullerene small molecular acceptor (SMA) systems remains largely unexplored. Through detailed characterizations (hard/soft X‐ray scattering) of the record‐efficiency polymer:SMA system with a close analog, quantitative morphological parameters are related to the device performance parameters and fundamental morphology–performance relationships that explain why additive use and thermal annealing are needed for optimized performance are established. A linear correlation between the average purity variations at small length scale (≈10 nm) and photovoltaic device characteristics across all processing protocols is observed in ≈12%‐efficiency polymer:SMA systems. In addition, molecular interactions as reflected by the estimated Flory–Huggins interaction parameters are used to provide context of the room temperature morphology results. Comparison with results from annealed devices suggests that the two SMA systems compared show upper and lower critical solution temperature behavior, respectively. The in‐depth understanding of the complex multilength scale nonfullerene OSC morphology may guide the device optimization and new materials development and indicates that thermodynamic properties of materials systems should be studied in more detail to aid in designing optimized protocols efficiently. DA - 2016/// PY - 2016/// DO - 10.1002/aenm.201602000 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85006728507&partnerID=MN8TOARS ER - TY - JOUR TI - High-Efficiency Polymer Solar Cells Enabled by Environment-Friendly Single-Solvent Processing AU - Zhang, Hao AU - Yao, Huifeng AU - Zhao, Wenchao AU - Ye, Long AU - Hou, Jianhui T2 - Advanced Energy Materials AB - Green-single-solvent-prepared polymer solar cells (PSCs) with efficiency of 9.7% based on PBDT-TS1:PC71BM are realized without resorting to any additives or further treatments. An environment-friendly solvent 2-methylanisole is proposed to fabricate PSCs for the first time. It reveals the possibility of replacing binary systems with a single solvent to fabricate highly efficient PSCs. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. DA - 2016/// PY - 2016/// DO - 10.1002/aenm.201502177 VL - 6 IS - 6 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000373149700016&KeyUID=WOS:000373149700016 KW - additive-free KW - green solvents KW - morphology KW - polymer solar cells KW - single solvents ER - TY - JOUR TI - Green-Solvent-Processed All-Polymer Solar Cells Containing a Perylene Diimide-Based Acceptor with an Efficiency over 6.5% AU - Li, Sunsun AU - Zhang, Hao AU - Zhao, Wenchao AU - Ye, Long AU - Yao, Huifeng AU - Yang, Bei AU - Zhang, Shaoqing AU - Hou, Jianhui T2 - Advanced Energy Materials AB - To realize high power conversion efficiencies (PCEs) in green‐solvent‐processed all‐polymer solar cells (All‐PSCs), a long alkyl chain modified perylene diimide (PDI)‐based polymer acceptor PPDIODT with superior solubility in nonhalogenated solvents is synthesized. A properly matched PBDT‐TS1 is selected as the polymer donor due to the red‐shifted light absorption and low‐lying energy level in order to achieve the complementary absorption spectrum and matched energy level between polymer donor and polymer acceptor. By utilizing anisole as the processing solvent, an optimal efficiency of 5.43% is realized in PBDT‐TS1/PPDIODT‐based All‐PSC with conventional configuration, which is comparable with that of All‐PSCs processed by the widely used binary solvent. Due to the utilization of an inverted device configuration, the PCE is further increased to over 6.5% efficiency. Notably, the best‐performing PCE of 6.58% is the highest value for All‐PSCs employing PDI‐based polymer acceptors and green‐solvent‐processed All‐PSCs. The excellent photovoltaic performance is mainly attributed to a favorable vertical phase distribution, a higher exciton dissociation efficiency ( P diss ) in the blend film, and a higher electrode carrier collection efficiency. Overall, the combination of rational molecular designing, material selection, and device engineering will motivate the efficiency breakthrough in green‐solvent‐processed All‐PSCs. DA - 2016/// PY - 2016/// DO - 10.1002/aenm.201501991 VL - 6 IS - 5 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000372525500009&KeyUID=WOS:000372525500009 KW - all-polymer solar cells KW - device engineering KW - green solvents KW - perylene diimides KW - polymer acceptors ER - TY - JOUR TI - Control of Mesoscale Morphology and Photovoltaic Performance in Diketopyrrolopyrrole-Based Small Band Gap Terpolymers AU - Ye, Long AU - Jiao, Xuechen AU - Zhang, Shaoqing AU - Yao, Huifeng AU - Qin, Yunpeng AU - Ade, Harald AU - Hou, Jianhui T2 - Advanced Energy Materials AB - Morphology control is one of the key strategies in optimizing the performance of organic photovoltaic materials, particularly for diketopyrrolopyrrole (DPP)‐based donor polymers. The design of DPP‐based polymers that provide high power conversion efficiency (PCE) presents a significant challenge that requires optimization of both energetics and morphology. Herein, a series of high performance, small band gap DPP‐based terpolymers are designed via two‐step side chain engineering, namely introducing alternating short and long alkyls for reducing the domain spacing and inserting alkylthio for modulating the energy levels. The new DPP‐based terpolymers are compared to delineate how the side chain impacts the mesoscale morphology. By employing the alkylthio‐substituted terpolymer PBDPP‐TS, the new polymer solar cell (PSC) device realizes a good balance of a high V oc of 0.77 V and a high J sc over 15 mA cm −2 , and thus realizes desirable PCE in excess of 8% and 9.5% in single junction and tandem PSC devices, respectively. The study indicates better control of domain purity will greatly improve performance of single junction DPP‐based PSCs toward 10% efficiency. More significantly, the utility of this stepwise side chain engineering can be readily expanded to other classes of well‐defined copolymers and triggers efficiency breakthroughs in novel terpolymers for photovoltaic and related electronic applications. DA - 2016/// PY - 2016/// DO - 10.1002/aenm.201601138 VL - 7 IS - 3 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85005777590&partnerID=MN8TOARS KW - diketopyrrolopyrrole KW - domain purity KW - domain size KW - small band gap KW - terpolymers ER - TY - BOOK TI - CHAPTER 2: New polymer donors for polymer solar cells AU - Ye, L. AU - Li, S. AU - Hou, J. AB - Conjugated polymers have been regarded as promising candidates in organic photovoltaics owing to the outstanding electronic, optical and mechanical flexible properties. In this chapter, first, we summarize and discuss the requirements and design strategies of donor polymers in polymer solar cells (PSCs). Second, the design concepts and representative donor–acceptor (D–A) copolymer donors based on six types of donor building blocks are discussed. Notably, the blooming developments of novel two-dimensional conjugated polymer donors are emphasized. Third, the design considerations and examples of novel terpolymer donors are introduced. Finally, we summarize the future directions and approaches to developing higher performance donor polymers for photovoltaic applications. DA - 2016/// PY - 2016/// DO - 10.1039/9781782622307-00032 VL - 2016-January SE - 32-77 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84952360276&partnerID=MN8TOARS ER - TY - JOUR TI - Dialkylthio Substitution: An Effective Method to Modulate the Molecular Energy Levels of 2D-BDT Photovoltaic Polymers AU - Yao, H. AU - Zhang, H. AU - Ye, L. AU - Zhao, W. AU - Zhang, S. AU - Hou, J. T2 - ACS Applied Materials and Interfaces AB - Dialkylthio-substituted thienyl-benzodithiophene (BDT-DST) was designed and synthesized as a building block to modulate the molecular levels of the conjugated polymers, and three copolymers named PDST-BDD, PDST-TT and PDST-DPP were prepared and applied in polymer solar cells (PSCs). Theoretical calculations and electrochemical cyclic voltammetry (CV) measurement suggested that the dialkylthio group could decrease the molecular energy levels of the resulting polymers distinctly. The open-circuit voltage (VOC) of PSC devices based on PDST-BDD, PDST-TT, and PDST-DPP are as high as 1.0, 0.98, and 0.88 V, respectively, which are ∼0.15 V higher than those of the corresponding alky-substituted analogues. Moreover, the influence of the dialkylthio group on the absorption spectra, crystalline properties, hole mobilities, and blend morphologies of the polymers was also investigated. The results indicate that the dialkythio substitution is an effective method to modulate the molecular energy levels and that the BDT-DST unit has potential for constructing high-efficiency photovoltaic polymers. DA - 2016/// PY - 2016/// DO - 10.1021/acsami.5b07311 VL - 8 IS - 6 SP - 3575-3583 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84959017081&partnerID=MN8TOARS KW - conjugated polymer KW - polymer solar cell KW - photovoltaic polymer KW - molecular energy levels KW - dialkylthio substitution ER - TY - JOUR TI - Effectively Improving Extinction Coefficient of Benzodithiophene and Benzodithiophenedione-based Photovoltaic Polymer by Grafting Alkylthio Functional Groups AU - Wang, Qi AU - Zhang, Shaoqing AU - Xu, Bowei AU - Ye, Long AU - Yao, Huifeng AU - Cui, Yong AU - Zhang, Hao AU - Yuan, Wenxia AU - Hou, Jianhui T2 - Chemistry-an Asian Journal AB - Alkylthio groups have received much attention in the polymer community for their molecular design applications in polymer solar cells. In this work, alkylthio substitution on the conjugated thiophene side chains in benzodithiophene (BDT) and benzodithiophenedione (BDD)-based photovoltaic polymer was used to improve the extinction coefficient. The introduction of alkylthio groups into the polymer increased its extinction coefficient while the HOMO levels, bandgaps, and absorption bands remained the same. Thus, the short circuit current density (Jsc ) and the efficiency of the device were much better than those of the control device. Thus, introducing the alkylthio functional group in polymer is an effective method to tune the extinction coefficient of photovoltaic polymer. This provides a new path to improve photovoltaic performance without increasing active layer thickness, which will be very helpful to design advanced photovoltaic materials for high photovoltaic performance. DA - 2016/// PY - 2016/// DO - 10.1002/asia.201501387 VL - 11 IS - 19 SP - 2650-2655 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000387464000006&KeyUID=WOS:000387464000006 KW - alkylthio group KW - extinction coefficients KW - polymers KW - solar cells KW - structure-activity relationships ER - TY - JOUR TI - Breaking the 10% Efficiency Barrier in Organic Photovoltaics: Morphology and Device Optimization of Well-Known PBDTTT Polymers AU - Zhang, Shaoqing AU - Ye, Long AU - Hou, Jianhui T2 - Advanced Energy Materials AB - With the advances in organic photovoltaics (OPVs), the invention of model polymers with superior properties and wide applicability is of vital importance to both the academic and industrial communities. The recent inspiring advances in OPV research have included the emergence of poly(benzodithiophene‐co‐thieno[3,4‐b]thiophene) (PBDTTT)‐based materials. Through the combined efforts on PBDTTT polymers, over 10% efficiencies have been realized recently in various types of OPV devices. This review attempts to critically summarize the recent advances with respect to five well‐known PBDTTT polymers and their design considerations, basic properties, photovoltaic performance, as well as device application in conventional, inverted, tandem solar cells. These PBDTTT polymers also make great contributions to the rapid advances in the field of emerging ternary blends and fullerene‐free OPVs with top performances. Addtionally, new challenges in developing novel photovoltaic polymers with more superior properties are prospected. More importantly, the research of highly efficient PBDTTT‐based polymers provides useful insights and builds fundamentals for new types of OPV applications with various architectures. DA - 2016/// PY - 2016/// DO - 10.1002/aenm.201502529 VL - 6 IS - 11 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000379311500008&KeyUID=WOS:000379311500008 ER - TY - JOUR TI - Improving the open-circuit voltage of alkylthio-substituted photovoltaic polymers via post-oxidation AU - Li, Sunsun AU - Ye, Long AU - Wang, Qi AU - Zhang, Shaoqing AU - Zhao, Wenchao AU - Hou, Jianhui T2 - Organic Electronics AB - Molecular designing of photovoltaic polymers based on benzodithiophene (BDT) building blocks for high power conversion efficiency (PCE) in polymer solar cells (PSCs) arouse much attention in the past few years. To meliorate the energy levels of photovoltaic polymers featuring alkylthio substituted BDT units, a novel post-polymerization oxidation method was proposed applied in converting sulfur atom into sulfonyl group on side chains of the pristine polymer PBT-S. After treating with tiny amount of meta-chloroperoxybenzoic acid (m-CPBA) and hydrogen peroxide (H2O2), two batches of the target polymers, namely, PBT-SO2-M and PBT-SO2-H were prepared for the first time, respectively. The photochemical and electrochemical results indicate that both the HOMO levels are distinctly dropped with almost no influence on band gaps by introducing strong electron-withdrawing sulfonyl groups on side chains of BDT. Accordingly, the photovoltaic results reveal that the Voc of devices based on PBT-SO2-M and PBT-SO2-H are 0.81, 0.71 V which are 0.17 and 0.07 V higher than that of pristine polymer PBT-S, respectively. Moreover, the Jsc and PCE of PBT-SO2-H devices are comparable with those of the devices based on PBT-S. Overall, this work suggests that the molecular energy levels of D–A copolymers can be effectively tuned by a post-oxidation method. DA - 2016/1/1/ PY - 2016/1/1/ DO - 10.1016/j.orgel.2015.10.004 VL - 28 SP - 39-46 UR - https://doi.org/10.1016/j.orgel.2015.10.004 KW - Polymer solar cells KW - Post-oxidation KW - Open-circuit voltage KW - Alkylthio KW - Sulfonyl ER - TY - JOUR TI - Observation of Shell Structure, Electronic Screening, and Energetic Limiting in Sparks AU - Bataller, A. AU - Putterman, S. AU - Pree, S. AU - Koulakis, J. T2 - Physical Review Letters AB - We study the formation of micron-sized spark discharges in high-pressure xenon on the nanosecond time scale. The spark's energy per length is measured through the expansion dynamics of the generated shock wave, and is observed to scale linearly with the spark radius. At the same time, the surface temperature of the spark channel remains constant. Together, these observations allow us to conclude that the spark channel, up to 40 μm in overall radius, is actually an energetically hollow shell about 20 μm thick. Further, the energy per nucleus in the shell is about 15 eV, independent of size and density. To reconcile these findings with the opacity to visible light, we appeal to collective screening processes that dramatically lower the effective ionization potential, allowing a much higher electron density than is otherwise expected. Thus, nanosecond measurements of sparks provide access to the thermodynamics and kinetics of strongly correlated plasmas. DA - 2016/8/19/ PY - 2016/8/19/ DO - 10.1103/PhysRevLett.117.085001 VL - 117 IS - 8 SP - 085001 J2 - Phys. Rev. Lett. LA - en OP - SN - 0031-9007 1079-7114 UR - http://dx.doi.org/10.1103/PhysRevLett.117.085001 DB - Crossref ER - TY - JOUR TI - Efficient Charge Transfer and Fine-Tuned Energy Level Alignment in a THF-Processed Fullerene-Free Organic Solar Cell with 11.3% Efficiency AU - Zheng, Zhong AU - Awartani, Omar M. AU - Gautam, Bhoj AU - Liu, Delong AU - Qin, Yunpeng AU - Li, Wanning AU - Bataller, Alexander AU - Gundogdu, Kenan AU - Ade, Harald AU - Hou, Jianhui AU - al., T2 - Advanced Materials AB - Fullerene-free organic solar cells show over 11% power conversion efficiency, processed by low toxic solvents. The applied donor and acceptor in the bulk heterojunction exhibit almost the same highest occupied molecular orbital level, yet exhibit very efficient charge creation. DA - 2016/11/28/ PY - 2016/11/28/ DO - 10.1002/adma.201604241 VL - 29 IS - 5 SP - 1604241 J2 - Adv. Mater. LA - en OP - SN - 0935-9648 UR - http://dx.doi.org/10.1002/adma.201604241 DB - Crossref ER - TY - JOUR TI - Efficient organic solar cells processed from hydrocarbon solvents AU - Zhao, Jingbo AU - Li, Yunke AU - Yang, Guofang AU - Jiang, Kui AU - Lin, Haoran AU - Ade, Harald AU - Ma, Wei AU - Yan, He T2 - Nature Energy DA - 2016/1/25/ PY - 2016/1/25/ DO - 10.1038/nenergy.2015.27 VL - 1 IS - 2 J2 - Nat Energy LA - en OP - SN - 2058-7546 UR - http://dx.doi.org/10.1038/nenergy.2015.27 DB - Crossref ER - TY - JOUR TI - Fast charge separation in a non-fullerene organic solar cell with a small driving force AU - Liu, Jing AU - Chen, Shangshang AU - Qian, Deping AU - Gautam, Bhoj AU - Yang, Guofang AU - Zhao, Jingbo AU - Bergqvist, Jonas AU - Zhang, Fengling AU - Ma, Wei AU - Ade, Harald AU - Inganäs, Olle AU - Gundogdu, Kenan AU - Gao, Feng AU - Yan, He T2 - Nature Energy DA - 2016/6/27/ PY - 2016/6/27/ DO - 10.1038/nenergy.2016.89 VL - 1 IS - 7 J2 - Nat Energy LA - en OP - SN - 2058-7546 UR - http://dx.doi.org/10.1038/nenergy.2016.89 DB - Crossref ER - TY - JOUR TI - Ultrafast resonant soft x-ray diffraction dynamics of the charge density wave in TbTe 3 AU - Moore, R. G. AU - Lee, W. S. AU - Kirchman, P. S. AU - Chuang, Y. D. AU - Kemper, A. F. AU - Trigo, M. AU - Patthey, L. AU - Lu, D. H. AU - Krupin, O. AU - Yi, M. AU - Reis, D. A. AU - Doering, D. AU - Denes, P. AU - Schlotter, W. F. AU - Turner, J. J. AU - Hays, G. AU - Hering, P. AU - Benson, T. AU - Chu, J.-H. AU - Devereaux, T. P. AU - Fisher, I. R. AU - Hussain, Z. AU - Shen, Z.-X. T2 - Phys. Rev. B AB - Understanding the emergence of collective behavior in correlated electron systems remains at the forefront of modern condensed matter physics. Disentangling the degrees of freedom responsible for collective behavior can lead to insights into the microscopic origins of emergent properties and phase transitions. Utilizing an optical pump, resonant soft x-ray diffraction probe we are able to track, in real time, the dynamics of the charge density wave (CDW) in ${\mathrm{TbTe}}_{3}$, a model system that violates traditional views of a Fermi surface nested CDW. We observe coherent oscillations corresponding to the CDW amplitude mode at $2.4$ THz and a coherent optical phonon mode at $\ensuremath{\sim}1.7\phantom{\rule{0.16em}{0ex}}\mathrm{THz}$. We show how such observations reveal the anisotropic energy optimization between in-plane Te charge density modulations and the three-dimensional lattice coupling. DA - 2016/1// PY - 2016/1// DO - 10.1103/physrevb.93.024304 VL - 93 IS - 2 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000369218500004&KeyUID=WOS:000369218500004 ER - TY - JOUR TI - The role of average time dependence on the relaxation of excited electron populations in nonequilibrium many-body physics AU - Kemper, A. F. AU - Krishnamurthy, H. R. AU - Freericks, J. K. T2 - Fortschr. Phys. AB - We examine the exact equation of motion for the relaxation of populations of strongly correlated electrons after a nonequilibrium excitation by a pulsed field, and prove that the populations do not change when the Green's functions have no average time dependence. We show how the average time dependence enters into the equation of motion to lowest order and describe what governs the relaxation process of the electron populations in the long‐time limit. While this result may appear, on the surface, to be required by any steady‐state solution, the proof is nontrivial, and provides new critical insight into how nonequilibrium populations relax, which goes beyond the assumption that they thermalize via a simple relaxation rate determined by the imaginary part of the self‐energy, or that they can be described by a quasi‐equilibrium condition with a Fermi‐Dirac distribution and a time‐dependent temperature. We also discuss the implications of this result to approximate theories, which may not satisfy the exact relation in the equation of motion. DA - 2016/8// PY - 2016/8// DO - 10.1002/prop.201600042 VL - 8 KW - Population dynamics KW - nonequilibrium many-body problem KW - thermalization KW - exact results KW - long-time limit ER - TY - JOUR TI - Virtual-tissue computer simulations define the roles of cell adhesion and proliferation in the onset of kidney cystic disease AU - Belmonte, Julio M. AU - Clendenon, Sherry G. AU - Oliveira, Guilherme M. AU - Swat, Maciej H. AU - Greene, Evan V. AU - Jeyaraman, Srividhya AU - Glazier, James A. AU - Bacallao, Robert L. T2 - Molecular Biology of the Cell AB - In autosomal dominant polycystic kidney disease (ADPKD), cysts accumulate and progressively impair renal function. Mutations in PKD1 and PKD2 genes are causally linked to ADPKD, but how these mutations drive cell behaviors that underlie ADPKD pathogenesis is unknown. Human ADPKD cysts frequently express cadherin-8 (cad8), and expression of cad8 ectopically in vitro suffices to initiate cystogenesis. To explore cell behavioral mechanisms of cad8-driven cyst initiation, we developed a virtual-tissue computer model. Our simulations predicted that either reduced cell–cell adhesion or reduced contact inhibition of proliferation triggers cyst induction. To reproduce the full range of cyst morphologies observed in vivo, changes in both cell adhesion and proliferation are required. However, only loss-of-adhesion simulations produced morphologies matching in vitro cad8-induced cysts. Conversely, the saccular cysts described by others arise predominantly by decreased contact inhibition, that is, increased proliferation. In vitro experiments confirmed that cell–cell adhesion was reduced and proliferation was increased by ectopic cad8 expression. We conclude that adhesion loss due to cadherin type switching in ADPKD suffices to drive cystogenesis. Thus, control of cadherin type switching provides a new target for therapeutic intervention. DA - 2016/// PY - 2016/// DO - 10.1091/mbc.E16-01-0059 VL - 27 IS - 22 SP - 3673-3685 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000387391400027&KeyUID=WOS:000387391400027 ER - TY - JOUR TI - Large-scale microtubule networks contract quite well AU - Belmonte, Julio M. AU - Nedelec, Francois T2 - Elife AB - The quantitative investigation of how networks of microtubules contract can boost our understanding of actin biology. DA - 2016/// PY - 2016/// DO - 10.7554/eLife.14076 VL - 5 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000371867900001&KeyUID=WOS:000371867900001 ER - TY - JOUR TI - Filopodial-Tension Model of Convergent-Extension of Tissues AU - Belmonte, Julio M. AU - Swat, Maciej H. AU - Glazier, James A. T2 - PLOS Computational Biology AB - In convergent-extension (CE), a planar-polarized epithelial tissue elongates (extends) in-plane in one direction while shortening (converging) in the perpendicular in-plane direction, with the cells both elongating and intercalating along the converging axis. CE occurs during the development of most multicellular organisms. Current CE models assume cell or tissue asymmetry, but neglect the preferential filopodial activity along the convergent axis observed in many tissues. We propose a cell-based CE model based on asymmetric filopodial tension forces between cells and investigate how cell-level filopodial interactions drive tissue-level CE. The final tissue geometry depends on the balance between external rounding forces and cell-intercalation traction. Filopodial-tension CE is robust to relatively high levels of planar cell polarity misalignment and to the presence of non-active cells. Addition of a simple mechanical feedback between cells fully rescues and even improves CE of tissues with high levels of polarity misalignments. Our model extends easily to three dimensions, with either one converging and two extending axes, or two converging and one extending axes, producing distinct tissue morphologies, as observed in vivo. DA - 2016/6/20/ PY - 2016/6/20/ DO - 10.1371/journal.pcbi.1004952 VL - 12 IS - 6 SP - e1004952 UR - http://dx.doi.org/10.1371/journal.pcbi.1004952 ER - TY - JOUR TI - A Liver-Centric Multiscale Modeling Framework for Xenobiotics AU - Sluka, James P. AU - Fu, Xiao AU - Swat, Maciej AU - Belmonte, Julio M. AU - Cosmanescu, Alin AU - Clendenon, Sherry G. AU - Wambaugh, John F. AU - Glazier, James A. T2 - PLOS ONE AB - We describe a multi-scale, liver-centric in silico modeling framework for acetaminophen pharmacology and metabolism. We focus on a computational model to characterize whole body uptake and clearance, liver transport and phase I and phase II metabolism. We do this by incorporating sub-models that span three scales; Physiologically Based Pharmacokinetic (PBPK) modeling of acetaminophen uptake and distribution at the whole body level, cell and blood flow modeling at the tissue/organ level and metabolism at the sub-cellular level. We have used standard modeling modalities at each of the three scales. In particular, we have used the Systems Biology Markup Language (SBML) to create both the whole-body and sub-cellular scales. Our modeling approach allows us to run the individual sub-models separately and allows us to easily exchange models at a particular scale without the need to extensively rework the sub-models at other scales. In addition, the use of SBML greatly facilitates the inclusion of biological annotations directly in the model code. The model was calibrated using human in vivo data for acetaminophen and its sulfate and glucuronate metabolites. We then carried out extensive parameter sensitivity studies including the pairwise interaction of parameters. We also simulated population variation of exposure and sensitivity to acetaminophen. Our modeling framework can be extended to the prediction of liver toxicity following acetaminophen overdose, or used as a general purpose pharmacokinetic model for xenobiotics. DA - 2016/9/16/ PY - 2016/9/16/ DO - 10.1371/journal.pone.0162428 VL - 11 IS - 9 SP - e0162428 ER - TY - JOUR TI - Nonaffine deformation under compression and decompression of a flow-stabilized solid AU - Ortiz, Carlos P. AU - Riehn, Robert AU - Daniels, Karen E. T2 - JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT AB - Understanding the particle-scale transition from elastic deformation to plastic flow is central to making predictions about the bulk material properties and response of disordered materials. To address this issue, we perform experiments on flow-stabilized solids composed of micron-scale spheres within a microfluidic channel, in a regime where particle inertia is negligible. Each solid heap exists within a stress gradient imposed by the flow, and we track the positions of particles in response to single impulses of fluid-driven compression or decompression. We find that the resulting deformation field is well-decomposed into an affine field, with a constant strain profile throughout the solid, and a non-affine field. The magnitude of this non-affine response decays with the distance from the free surface in the long-time limit, suggesting that the distance from jamming plays a significant role in controlling the length scale of plastic flow. Finally, we observe that compressive pulses create more rearrangements than decompressive pulses, an effect that we quantify using the $D^2_\mathrm{min}$ statistic for non-affine motion. Unexpectedly, the time scale for the compression response is shorter than for decompression at the same strain (but unequal pressure), providing insight into the coupling between deformation and cage-breaking. DA - 2016/8// PY - 2016/8// DO - 10.1088/1742-5468/2016/08/084003 VL - 2016 IS - 8 SP - SN - 1742-5468 KW - Brownian motion KW - colloidal glasses KW - elasticity KW - plasticity ER - TY - JOUR TI - Single-molecule FRET to measure conformational dynamics of DNA mismatch repair proteins AU - Gauer, J. W. AU - LeBlanc, S. AU - Hao, P. AU - Qiu, R. AU - Case, B. C. AU - Sakato, M. AU - Hingorani, M. M. AU - Erie, D. A. AU - Weninger, K. R. T2 - Single-molecule enzymology: fluorescence-based and high-throughput methods DA - 2016/// PY - 2016/// VL - 581 SP - 285-315 ER - TY - CONF TI - Fixed-node and fixed-phase approximations and their relationship to variable spins in quantum monte carlo AU - Melton, C. A. AU - Mitas, L. AB - We compare the fixed-phase approximation with the better known, but closely related, fixed-node approximation on several testing examples. We found that both approximations behave very similarly with the fixed-phase results being very close to the fixed-node method whenever nodes/phase were of high and comparable accuracy. The fixed-phase exhibited larger biases when the trial wave functions errors in the nodes/phase were intentionally driven to unrealistically large values. We also present a formalism that enables one to describe wave functions with the full antisymmetry in spin-spatial degrees of freedom using our recently developed method for systems with spins as fully quantum variables. This opens new possibilities for simulations of fermionic systems in the fixed-phase approximation formalism. C2 - 2016/// C3 - Recent progress in quantum monte carlo DA - 2016/// DO - 10.1021/bk-2016-1234.ch001 VL - 1234 SP - 1-13 ER - TY - JOUR TI - The rho-meson time-like form factors in sub-leading pQCD AU - Melo, J. P. B. C. AU - Ji, Chueng-Ryong AU - Frederico, T. T2 - PHYSICS LETTERS B AB - The annihilation/production process e++e−→ρ++ρ− is studied with respect to the universal perturbative QCD (pQCD) predictions. Sub-leading contributions are considered together with the universal leading pQCD amplitudes such that the matrix elements of the ρ-meson electromagnetic current satisfy the constraint from the light-front angular condition. The data from the BaBar collaboration for the time-like ρ-meson form factors at s=10.58GeV puts a stringent test to the onset of asymptotic pQCD behavior. The e++e−→ρ++ρ− cross-section for s between 60GeV2 and 160GeV2 is predicted where the sub-leading contributions are still considerable. DA - 2016/12/10/ PY - 2016/12/10/ DO - 10.1016/j.physletb.2016.10.018 VL - 763 SP - 87-93 SN - 1873-2445 KW - Perturbative QCD KW - rho-meson KW - Electromagnetic form factors ER - TY - JOUR TI - The metal abundances across cosmic time (mact) survey. I. Optical spectroscopy in the subaru deep field AU - Ly, C. AU - Malhotra, S. AU - Malkan, M. A. AU - Rigby, J. R. AU - Kashikawa, N. AU - Reyes, M. A. AU - Rhoads, J. E. T2 - Astrophysical Journal Supplement Series AB - Deep rest-frame optical spectroscopy is critical for characterizing and understanding the physical conditions and properties of the ionized gas in galaxies. Here, we present a new spectroscopic survey called "Metal Abundances across Cosmic Time" or , which will obtain rest-frame optical spectra for ∼3000 emission-line galaxies. This paper describes the optical spectroscopy that has been conducted with MMT/Hectospec and Keck/DEIMOS for ≈1900 z = 0.1–1 emission-line galaxies selected from our narrowband and intermediate-band imaging in the Subaru Deep Field. In addition, we present a sample of 164 galaxies for which we have measured the weak [O iii]λ4363 line (66 with at least 3σ detections and 98 with significant upper limits). This nebular emission line determines the gas-phase metallicity by measuring the electron temperature of the ionized gas. This paper presents the optical spectra, emission-line measurements, interstellar properties (e.g., metallicity, gas density), and stellar properties (e.g., star formation rates, stellar mass). Paper II of the survey (Ly et al.) presents the first results on the stellar mass–gas metallicity relation at z ≲ 1 using the sample with [O iii]λ4363 measurements. DA - 2016/// PY - 2016/// DO - 10.3847/0067-0049/226/1/5 VL - 226 IS - 1 ER - TY - JOUR TI - X-RAY AND GAMMA-RAY EMISSION FROM MIDDLE-AGED SUPERNOVA REMNANTS IN CAVITIES. I. SPHERICAL SYMMETRY AU - Tang, Zhu AU - Reynolds, Stephen P. AU - Ressler, Sean M. T2 - ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES AB - We present analytical and numerical studies of models of supernova-remnant (SNR) blast waves in one spatial dimension expanding into uniform media and interacting with a denser cavity wall. We predict the nonthermal emission from such blast waves: synchrotron emission at radio and X-ray energies, and bremsstrahlung, inverse-Compton emission (from cosmic-microwave-background seed photons; ICCMB), and emission from the decay of mesons produced in inelastic collisions between accelerated ions and thermal gas, at GeV and TeV energies. Accelerated-particle spectra are assumed to be power laws with exponential cutoffs at energies limited by the remnant age or (for electrons, if lower) by radiative losses. We compare the results with those from homogeneous (“one-zone”) models. Such models give fair representations of the 1D results for uniform media, but cavity-wall interactions produce effects for which one-zone models are inadequate. We study the time evolution of SNR morphology and emission with time. Strong morphological differences exist between ICCMB and -decay emission; at some stages, the TeV emission can be dominated by the former and the GeV by the latter, resulting in strong energy dependence of morphology. Integrated gamma-ray spectra show apparent power laws of slopes that vary with time, but do not indicate the energy distribution of a single population of particles. As observational capabilities at GeV and TeV energies improve, spatial inhomogeneity in SNRs will need to be accounted for. DA - 2016/12// PY - 2016/12// DO - 10.3847/1538-4365/227/2/28 VL - 227 IS - 2 SP - SN - 1538-4365 UR - https://doi.org/10.3847/1538-4365/227/2/28 KW - ISM: supernova remnants KW - radiation mechanisms: nonthermal KW - X-rays: ISM ER - TY - JOUR TI - Non-extensive statistics in spin precession AU - Bales, M. J. AU - Fierlinger, P. AU - Golub, R. T2 - Europhysics Letters DA - 2016/// PY - 2016/// VL - 116 IS - 4 ER - TY - JOUR TI - Energy dissipation from a correlated system driven out of equilibrium AU - Rameau, J. D. AU - Freutel, S. AU - Kemper, A. F. AU - Sentef, M. A. AU - Freericks, J. K. AU - Avigo, I. AU - Ligges, M. AU - Rettig, L. AU - Yoshida, Y. AU - Eisaki, H. AU - Schneeloch, J. AU - Zhong, R. D. AU - Xu, Z. J. AU - Gu, G. D. AU - Johnson, P. D. AU - Bovensiepen, U. T2 - Nature Communications AB - In complex materials various interactions have important roles in determining electronic properties. Angle-resolved photoelectron spectroscopy (ARPES) is used to study these processes by resolving the complex single-particle self-energy and quantifying how quantum interactions modify bare electronic states. However, ambiguities in the measurement of the real part of the self-energy and an intrinsic inability to disentangle various contributions to the imaginary part of the self-energy can leave the implications of such measurements open to debate. Here we employ a combined theoretical and experimental treatment of femtosecond time-resolved ARPES (tr-ARPES) show how population dynamics measured using tr-ARPES can be used to separate electron-boson interactions from electron-electron interactions. We demonstrate a quantitative analysis of a well-defined electron-boson interaction in the unoccupied spectrum of the cuprate Bi2Sr2CaCu2O8+x characterized by an excited population decay time that maps directly to a discrete component of the equilibrium self-energy not readily isolated by static ARPES experiments. DA - 2016/// PY - 2016/// DO - 10.1038/ncomms13761 VL - 7 SP - 13761 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000390052600001&KeyUID=WOS:000390052600001 ER - TY - JOUR TI - Attitudes of life science majors towards computational modeling in introductory physics AU - Lunk, Brandon R. AU - Beichner, Robert J. T2 - 2016 PHYSICS EDUCATION RESEARCH CONFERENCE DA - 2016/// PY - 2016/// DO - 10.1119/perc.2016.pr.047 SP - 208-211 SN - 2377-2379 ER - TY - JOUR TI - Van der Waals Force Isolation of Monolayer MoS2 AU - Gurarslan, Alper AU - Jiao, Shuping AU - Li, Tai-De AU - Li, Guoqing AU - Yu, Yiling AU - Gao, Yang AU - Riedo, Elisa AU - Xu, Zhiping AU - Cao, Linyou T2 - ADVANCED MATERIALS AB - Monolayer MoS2 can effectively screen the vdW interaction of underlying substrates with external systems by >90% because of the substantial increase in the separation between the substrate and external systems due to the presence of the monolayer. This substantial screening of vdW interactions by MoS2 monolayer is different from what reported at graphene. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. DA - 2016/12/7/ PY - 2016/12/7/ DO - 10.1002/adma.201601581 VL - 28 IS - 45 SP - 10055-10060 SN - 1521-4095 ER - TY - JOUR TI - Two-dimensional O(3) model at nonzero density: From dual lattice simulations to repulsive bosons AU - Bruckmann, Falk AU - Gattringer, Christof AU - Kloiber, Thomas AU - Sulejmanpasic, Tin T2 - PHYSICAL REVIEW D AB - We discuss the thermodynamics of the O(3) nonlinear sigma model in $1+1$ dimensions at nonzero chemical potential (equivalent to a magnetic field). In its conventional field theory representation the model suffers from a sign problem. By dualizing the model, we are able to fully access the nonzero density regime of an asymptotically free theory with dynamical mass gap at arbitrary chemical potential values. We find a quantum phase transition at zero temperature where as a function of the chemical potential the density assumes a nonzero value. Measuring the spin stiffness we present evidence for a corresponding dynamical critical exponent $z$ close to 2. The low energy O(3) model is conjectured to be described by a massive boson triplet with repulsive interactions. We confirm the universal square-root behavior expected for such a system at low density (and temperature) and compare our data to the results of Bethe Ansatz solutions of the relativistic and nonrelativistic one-dimensional Bose gas. We also comment on a potential Berezinskii-Kosterlitz-Thouless transition at nonzero density. DA - 2016/12/2/ PY - 2016/12/2/ DO - 10.1103/physrevd.94.114503 VL - 94 IS - 11 SP - SN - 2470-0029 ER - TY - JOUR TI - THE LINK BETWEEN RARE-EARTH PEAK FORMATION AND THE ASTROPHYSICAL SITE OF THE R PROCESS AU - Mumpower, Matthew R. AU - McLaughlin, Gail C. AU - Surman, Rebecca AU - Steiner, Andrew W. T2 - ASTROPHYSICAL JOURNAL AB - The primary astrophysical source of the rare earth elements is the rapid neutron capture process ($r$ process). The rare earth peak that is seen in the solar $r$-process residuals has been proposed to originate as a pile-up of nuclei during the end of the $r$ process. We introduce a new method utilizing Monte Carlo studies of nuclear masses in the rare earth region, that includes self-consistently adjusting $\beta$-decay rates and neutron capture rates, to find the mass surfaces necessary for the formation of the rare earth peak. We demonstrate our method with two types of astrophysical scenarios, one corresponding conditions typical of core-collapse supernova winds and one corresponding to conditions typical of the ejection of the material from the tidal tails of neutron star mergers. In each type of astrophysical conditions, this method successfully locates a region of enhanced stability in the mass surface that is responsible for the rare earth peak. For each scenario, we find that the change in the mass surface has qualitatively different features, thus future measurements can shed light on the type of environment in which the $r$ process occurred. DA - 2016/12/20/ PY - 2016/12/20/ DO - 10.3847/1538-4357/833/2/282 VL - 833 IS - 2 SP - SN - 1538-4357 KW - nuclear reactions KW - nucleosynthesis KW - abundances ER - TY - JOUR TI - Strange-quark asymmetry in the proton in chiral effective theory AU - Wang, X. G. AU - Ji, Chueng-Ryong AU - Melnitchouk, W. AU - Salamu, Y. AU - Thomas, A. W. AU - Wang, P. T2 - PHYSICAL REVIEW D AB - We perform a comprehensive analysis of the strange-antistrange parton distribution function (PDF) asymmetry in the proton in the framework of chiral effective theory, including the full set of lowest order kaon loop diagrams with off-shell and contact interactions, in addition to the usual on-shell contributions previously discussed in the literature. We identify the presence of $\delta$-function contributions to the $\bar s$ PDF at $x=0$, with a corresponding valence-like component of the $s$-quark PDF at larger $x$, which allows greater flexibility for the shape of $s-\bar s$. Expanding the moments of the PDFs in terms of the pseudoscalar kaon mass, we compute the leading nonanalytic behavior of the number and momentum integrals of the $s$ and $\bar s$ distributions, consistent with the chiral symmetry of QCD. We discuss the implications of our results for the understanding of the NuTeV anomaly and for the phenomenology of strange quark PDFs in global QCD analysis. DA - 2016/11/29/ PY - 2016/11/29/ DO - 10.1103/physrevd.94.094035 VL - 94 IS - 9 SP - SN - 2470-0029 ER - TY - JOUR TI - Nonstandard neutrino interactions in supernovae AU - Stapleford, Charles J. AU - Vaananen, Daavid J. AU - Kneller, James P. AU - McLaughlin, Gail C. AU - Shapiro, Brandon T. T2 - PHYSICAL REVIEW D AB - Nonstandard interactions (NSI) of neutrinos with matter can significantly alter neutrino flavor evolution in supernovae with the potential to impact explosion dynamics, nucleosynthesis, and the neutrinos signal. In this paper, we explore, both numerically and analytically, the landscape of neutrino flavor transformation effects in supernovae due to NSI and find a new, heretofore unseen transformation processes can occur. These new transformations can take place with NSI strengths well below current experimental limits. Within a broad swath of NSI parameter space, we observe symmetric and standard matter-neutrino resonances for supernovae neutrinos, a transformation effect previously only seen in compact object merger scenarios; in another region of the parameter space we find the NSI can induce neutrino collective effects in scenarios where none would appear with only the standard case of neutrino oscillation physics; and in a third region the NSI can lead to the disappearance of the high density Mikheyev-Smirnov-Wolfenstein resonance. Using a variety of analytical tools, we are able to describe quantitatively the numerical results allowing us to partition the NSI parameter according to the transformation processes observed. Our results indicate nonstandard interactions of supernova neutrinos provide a sensitive probe of beyond the Standard Model physics complementary to present and future terrestrial experiments. DA - 2016/11/29/ PY - 2016/11/29/ DO - 10.1103/physrevd.94.093007 VL - 94 IS - 9 SP - SN - 2470-0029 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85002112694&partnerID=MN8TOARS ER - TY - JOUR TI - New Nonperturbative Methods in Quantum Field Theory: From Large- N Orbifold Equivalence to Bions and Resurgence AU - Dunne, Gerald V. AU - Unsal, Mithat T2 - ANNUAL REVIEW OF NUCLEAR AND PARTICLE SCIENCE, VOL 66 AB - We present a broad conceptual introduction to some new ideas in nonperturbative quantum field theory (QFT) that have led to progress toward an understanding of quark confinement in gauge theories and, more broadly, toward a nonperturbative continuum definition of QFTs. We first present exact orbifold equivalences of supersymmetric and nonsupersymmetric QFTs in the large-N limit and exact equivalences of large-N theories in infinite volume to large-N theories in finite volume, or even at a single point. We discuss principles by which calculable QFTs are continuously connected to strong-coupling QFTs, allowing understanding of the physics of confinement or the absence thereof. We discuss the role of particular saddle solutions, termed bions, in weak-coupling calculable regimes. The properties of bions motivate an extension of semiclassical methods used to evaluate functional integrals to include families of complex saddles (Picard–Lefschetz theory). This analysis leads us to the resurgence program, which may provide a framework for combining divergent perturbation series with semiclassical instanton and bion/renormalon contributions. This program could provide a nonperturbative definition of the path integral. DA - 2016/// PY - 2016/// DO - 10.1146/annurev-nucl-102115-044755 VL - 66 SP - 245-272 SN - 1545-4134 KW - large-N orbifold and orientifold equivalence KW - volume independence KW - double-trace deformations KW - adiabatic continuity KW - semiclassical calculability KW - magnetic and neutral bions KW - resurgence KW - Picard-Lefschetz theory of path integration ER - TY - JOUR TI - Impact of an improved neutrino energy estimate on outflows in neutron star merger simulations AU - Foucart, Francois AU - O'Connor, Evan AU - Roberts, Luke AU - Kidder, Lawrence E. AU - Pfeiffer, Harald P. AU - Scheel, Mark A. T2 - PHYSICAL REVIEW D AB - Compact binary mergers involving at least one neutron star are important sources of gravitational waves. To fully describe such mergers, however, requires not only general relativity but also nuclear physics, hydrodynamics, and neutrino transport. The paper by Foucart et al. marks a significant step in this direction by showing the sensitivity of observables to the neutrino energy spectrum. DA - 2016/12/29/ PY - 2016/12/29/ DO - 10.1103/physrevd.94.123016 VL - 94 IS - 12 SP - SN - 2470-0029 ER - TY - JOUR TI - Hard X-ray emission from pulsar-wind nebulae AU - Reynoldst, Stephen P. T2 - JOURNAL OF PLASMA PHYSICS AB - Pulsar-wind nebulae emit an extremely broad spectrum of continuum radiation, from low radio frequencies to TeV gamma rays. The part of the spectral energy distribution (SED) from radio through MeV gamma rays is due to synchrotron emission from a distribution of relativistic electrons (or pairs) which can be described by one or more power laws. This spectrum exhibits that particle energy distribution, responsible also for the higher-energy (GeV–TeV) part of the SED, due to inverse-Compton upscattering of one of three photon fields: the synchrotron spectrum, the cosmic microwave background, or ambient optical/infrared photons. However, in a few sources, primary hadrons may produce GeV–TeV gamma rays through the decay of neutral pions produced in inelastic cosmic-ray collisions with thermal gas. The higher-energy end of the particle spectrum, producing synchrotron photons above approximately 10 keV, holds clues to the particle acceleration process. However, its detailed study requires imaging spectroscopy in this energy range, not available until the NuSTAR mission beginning in 2012, which performs true imaging between 3 and 78 keV with ${\sim}1^{\prime }$ angular resolution. I review NuSTAR observations of the first three pulsar-wind nebulae (PWNe) to be examined in this way: the Crab Nebula, G21.5–0.9 and MSH 15–5 2 . All three show spectral structure not previously known: spectral steepening in certain locations and overall source shrinkage with increasing photon energy. The Crab Nebula has different shrinkage rates along the torus and along the northwest counter-jet. The latter rate is similar to that for both the other sources (FWHM $\propto E^{m}$ with $m\sim -0.2$ ). I discuss implications of these results for models of particle transport in PWNe. DA - 2016/10// PY - 2016/10// DO - 10.1017/s0022377816000751 VL - 82 IS - 05 SP - SN - 1469-7807 UR - https://doi.org/10.1017/S0022377816000751 KW - relativistic flows KW - X-ray observations ER - TY - JOUR TI - Enhanced Crystallinity of Polymer Nanofibers without Loss of Nanofibrous Morphology via Heterogeneous Photothermal Annealing AU - Viswanath, Vidya AU - Maity, Somsubhra AU - Bochinski, Jason R. AU - Clarke, Laura I. AU - Gorga, Russell E. T2 - MACROMOLECULES AB - Poly(ethylene oxide) electrospun nanofibers with a low concentration of embedded gold nanoparticles (AuNP) were subjected to postfabrication annealing via photothermal heating from the nanoparticles. The results, including nanofibrous mat morphology, crystallinity fraction as a function of annealing time and modality, and average crystallite size, were compared with that for conventional heating at the same average temperature. Maximum crystallinity is achieved more quickly under photothermal heating, and higher maximum crystallinity values, approaching the theoretical maxima for an entangled polymer (∼80%), are obtained. Photothermal heating better preserves the unique nanostructured morphology of the nanofibrous mat whereas significant fiber thickening and loss of porosity occur under conventional annealing treatment. With photothermal heating, heat may be predominantly applied within amorphous material within the fiber, which provides energy for the amorphous chains to reorient and then possibly crystallize but while preserving existing crystalline regions as well as the temperature-fragile nanofiber surface. This occurs because nanoparticles are spontaneously segregated within amorphous material due to their characteristic size. In the complex environment of a polymeric nanofiber where crystalline, aligned amorphous, and random amorphous material are all present, further spontaneous segregation of the AuNP to the random amorphous material may occur which enables targeting of this higher barrier to crystallization population, leading to very high final crystallinity fractions. DA - 2016/12/27/ PY - 2016/12/27/ DO - 10.1021/acs.macromol.6b01655 VL - 49 IS - 24 SP - 9484-9492 SN - 1520-5835 ER - TY - JOUR TI - Energy-Level Modulation of Small-Molecule Electron Acceptors to Achieve over 12% Efficiency in Polymer Solar Cells AU - Li, Sunsun AU - Ye, Long AU - Zhao, Wenchao AU - Zhang, Shaoqing AU - Mukherjee, Subhrangsu AU - Ade, Harald AU - Hou, Jianhui T2 - ADVANCED MATERIALS AB - Fine energy-level modulations of small-molecule acceptors (SMAs) are realized via subtle chemical modifications on strong electron-withdrawing end-groups. The two new SMAs (IT-M and IT-DM) end-capped by methyl-modified dicycanovinylindan-1-one exhibit upshifted lowest unoccupied molecular orbital (LUMO) levels, and hence higher open-circuit voltages can be observed in the corresponding devices. Finally, a top power conversion efficiency of 12.05% is achieved. DA - 2016/11/9/ PY - 2016/11/9/ DO - 10.1002/adma.201602776 VL - 28 IS - 42 SP - 9423-+ SN - 1521-4095 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:27606970&KeyUID=MEDLINE:27606970 ER - TY - JOUR TI - Total prompt gamma-ray emission in fission AU - Wu, C. Y. AU - Chyzh, A. AU - Kwan, E. AU - Henserson, R. A. AU - Bredeweg, T. A. AU - Haight, R. C. AU - Hayes-Sterbenz, A. C. AU - Lee, H. Y. AU - O'Donnell, J. M. AU - Ullmann, J. L. T2 - CNR*15 - 5TH INTERNATIONAL WORKSHOP ON COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS AB - The total prompt γ-ray energy distributions for the neutron-induced fission of 235U, 239,241Pu at incident neutron energy of 0.025 eV ‒ 100 keV, and the spontaneous fission of 252Cf were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) array in coincidence with the detection of fission fragments by a parallel-plate avalanche counter. DANCE is a highly segmented, highly efficient 4π γ-ray calorimeter. Corrections were made to the measured distribution by unfolding the two-dimension spectrum of total γ-ray energy vs multiplicity using a simulated DANCE response matrix. The mean values of the total prompt γ-ray energy, determined from the unfolded distributions, are ~ 20% higher than those derived from measurements using single γ-ray detector for all the fissile nuclei studied. This raises serious concern on the validity of the mean total prompt γ-ray energy obtained from the product of mean values for both prompt γ-ray energy and multiplicity. DA - 2016/// PY - 2016/// DO - 10.1051/epjconf/201612201011 VL - 122 SP - SN - 2100-014X ER - TY - JOUR TI - Effective Riemannian Diffusion Model for Conformational Dynamics of Biomolecular Systems AU - Fakharzadeh, Ashkan AU - Moradi, Mahmoud T2 - JOURNAL OF PHYSICAL CHEMISTRY LETTERS AB - We present a Riemannian formalism for effective diffusion of biomolecules in collective variable spaces that provides a robust framework for conformational free energy calculation methods. Unlike their Euclidean counterparts, the Riemannian potential of mean force (PMF) and minimum free energy path (MFEP) are invariant under coordinate transformations. The presented formalism can be readily employed to modify the collective variable based enhanced sampling techniques, such as umbrella sampling (US) commonly used in biomolecular simulations, to take into account the role of intrinsic geometry of collective variable space. Although our model is mathematically equivalent to a Euclidean diffusion with a position-dependent diffusion tensor, the Riemannian formulation provides a more convenient framework for free energy calculation methods and path-finding algorithms aimed at characterizing the effective conformational dynamics of biomolecules. A simple three-dimensional toy model and a pentapeptide (met-enkephalin) simulated in an explicit solvent environment are used to illustrate the workings of the formalism and its implementation. DA - 2016/12/15/ PY - 2016/12/15/ DO - 10.1021/acs.jpclett.6b02208 VL - 7 IS - 24 SP - 4980-4987 SN - 1948-7185 ER - TY - JOUR TI - Deconstructing zero: resurgence, supersymmetry and complex saddles AU - Dunne, Gerald V. AU - Unsal, Mithat T2 - JOURNAL OF HIGH ENERGY PHYSICS AB - We explain how a vanishing, or truncated, perturbative expansion, such as often arises in semi-classically tractable supersymmetric theories, can nevertheless be related to fluctuations about non-perturbative sectors via resurgence. We also demonstrate that, in the same class of theories, the vanishing of the ground state energy (unbroken supersymmetry) can be attributed to the cancellation between a real saddle and a complex saddle (with hidden topological angle π), and positivity of the ground state energy (broken supersymmetry) can be interpreted as the dominance of complex saddles. In either case, despite the fact that the ground state energy is zero to all orders in perturbation theory, all orders of fluctuations around non-perturbative saddles are encoded in the perturbative E (N, g). We illustrate these ideas with examples from supersymmetric quantum mechanics and quantum field theory. DA - 2016/12/1/ PY - 2016/12/1/ DO - 10.1007/jhep12(2016)002 IS - 12 SP - SN - 1029-8479 KW - Nonperturbative Effects KW - Supersymmetric gauge theory KW - Supersymmetry Breaking ER - TY - JOUR TI - Comment on "Fluid modeling of a high-voltage nanosecond pulsed xenon microdischarge" [Phys. Plasmas 23, 073513 (2016)] AU - Koulakis, J. AU - Bataller, A. AU - Pree, S. AU - Putterman, S. T2 - PHYSICS OF PLASMAS AB - Simulations of sparks in 10 atmosphere Xenon gas by Levko and Raja [Phys. Plasmas 23, 073513 (2016)] are unable to reproduce the experimental fact of their opacity to visible light [Bataller et al., Appl. Phys. Lett. 105, 223501 (2014)]. Levko and Raja have argued the discrepancy is due to enhanced ionization from the probing laser radiation and/or cathode field emission. Having observed comparable opacity in similar systems without probing lasers and without electrodes, we instead argue that the enhanced ionization is a thermodynamic result of dense plasma screening effects that lower the effective ionization potential. Levko and Raja do not adequately address these density effects in their spark discharge simulations. DA - 2016/11// PY - 2016/11// DO - 10.1063/1.4967851 VL - 23 IS - 11 SP - SN - 1089-7674 ER - TY - JOUR TI - Radial Profile of Plasma Flow Parameters Following Evolution of Electrothermal Polycarbonate Plasma into a Large Chamber Simulating Impurity Expansion in Fusion Reactor Vacuum Vessel AU - Majumdar, Rudrodip AU - Bourham, Mohamed A. T2 - JOURNAL OF FUSION ENERGY DA - 2016/12// PY - 2016/12// DO - 10.1007/s10894-016-0107-9 VL - 35 IS - 6 SP - 795-806 SN - 1572-9591 KW - Plasma flow KW - Fusion particle expansion KW - Impurity following disruption KW - Electrothermal simulation ER - TY - JOUR TI - Constraints on the s - (s)over-bar asymmetry of the proton in chiral effective theory AU - Wang, X. G. AU - Ji, Chueng-Ryong AU - Melnitchouk, W. AU - Salamu, Y. AU - Thomas, A. W. AU - Wang, P. T2 - PHYSICS LETTERS B AB - We compute the $s-\bar s$ asymmetry in the proton in chiral effective theory, using phenomenological constraints based upon existing data. Unlike previous meson cloud model calculations, which accounted for kaon loop contributions with on-shell intermediate states alone, this work includes off-shell terms and contact interactions, which impact the shape of the $s-\bar s$ difference. We identify a valence-like component of $s(x)$ which is balanced by a $\delta$-function contribution to $\bar s(x)$ at $x=0$, so that the integrals of $s$ and $\bar s$ over the experimentally accessible region $x > 0$ are not equal. Using a regularization procedure that preserves chiral symmetry and Lorentz invariance, we find that existing data limit the integrated value of the second moment of the asymmetry to the range $-0.07 \times 10^{-3} \leq \langle x(s-\bar s) \rangle \leq 1.12 \times 10^{-3}$ at a scale of $Q^2=1 $GeV$^2$. This is too small to account for the NuTeV anomaly and of the wrong sign to enhance it. DA - 2016/11/10/ PY - 2016/11/10/ DO - 10.1016/j.physletb.2016.09.014 VL - 762 SP - 52-56 SN - 1873-2445 KW - Strange asymmetry KW - Chiral symmetry KW - Kaon loops ER - TY - JOUR TI - A PCBM Electron Transport Layer Containing Small Amounts of Dual Polymer Additives that Enables Enhanced Perovskite Solar Cell Performance AU - Zhu, Zonglong AU - Xue, Qifan AU - He, Hexiang AU - Jiang, Kui AU - Hu, Zhicheng AU - Bai, Yang AU - Zhang, Teng AU - Xiao, Shuang AU - Gundogdu, Kenan AU - Gautam, Bhoj Raj AU - Ade, Harald AU - Huang, Fei AU - Wong, Kam Sing AU - Yip, Hin-Lap AU - Yang, Shihe AU - Yan, He T2 - ADVANCED SCIENCE AB - A polymer/PCBM hybrid electron transport layer is reported that enables high-performance perovskite solar cells with a high power conversion efficiency of 16.2% and with negligible hysteresis. Unlike previous approaches of reducing hysteresis by thermal annealing or fullerene passivation, the success of our approach can be mainly attributed to the doping of the PCBM layer using an insulating polymer (polystyrene) and an amine-containing polymeric semiconductor named PFNOX. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. The field of organic–inorganic metal halide perovskite solar cells (PKSCs) has seen impressive progresses in recent years.1 The rapidly increasing power conversion efficiency (PCE) of PKSCs has attracted much attention of both the academic and industrial research communities and makes PKSCs one of the most promising candidates for the next generation of large scale cost-competitive photovoltaic technology.2 The attractive features of PKSCs include high absorption characteristics, appropriate direct band gaps, high carrier mobility, long charge carrier diffusion length, low cost, and easy fabrication processes.3 These merits had pushed the PCE of PKSCs to a record value of 20.1% recently.4 The conventional PKSC structure5 consists of an electron transport layer (ETL) (e.g., TiO2) with the perovskite layer on top and then capped with a hole transport layer (HTL, such as spiro-OMeTAD). In the past two years, however, inverted structure PKSCs (with a typical structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/perovskite layer/phenyl-C61-butyric acid methyl ester (PCBM)/top electrode) have developed rapidly and can now achieve comparable PCEs with the conventional structure PKSCs.6 One of the main challenges for PKSCs is that typical PKSCs exhibit large hysteresis in their J–V characteristics, which makes PKSCs difficult to characterize or to produce in a reproducible and repeatable manner.[2],7 The hysteresis problem is typically less severe for conventional structure PKSCs based on the mesoporous TiO2. This is because the mesoscopic TiO2 offers a large surface area and the charges generated in the perovskite layer can be transported to the TiO2 mesoporous film or via the self-connected perovskite network.8 In contrast, it is more challenging to optimize the interfaces in planar-structure inverted PKSCs and to achieve a perfectly balanced electron and hole currents in the device. Thus far, several reports have shown hysteresis-less PKSCs by long-time thermal annealing, filling with PCBM,9 and by balancing the electron and hole transports in the perovskite cell.10 However, the majority of the reports on inverted PKSCs are still troubled with various extents of the hysteresis problem and there are limited reports of high-efficiency inverted PKSCs with completely eliminated hysteresis.11 Indicated by previous reports,[6],[11] the hysteresis problem could be related to the hole and electron transport layers (e.g., need to achieve balanced charge transport)[6] as well as the perovskite active layer (e.g., need to grow large crystals and eliminate traps in the perovskite active layer).[11] Therefore, the complete elimination of hysteresis in PKSCs may require the combination of different approaches that address different components of the perovskite cells. As most previous work has been focused more on the perovskite active layer than the PCBM ETL, we hope to improve the PCBM ETL to provide a simple and effective approach to complement previous ones. In our previous work, we have developed a series of polyfluorene-based semiconducting polymers that contain alkylamine side chains.[11],12 One of the classical materials in the family is PFNOX, which has been widely used as interfacial layers for organic light emitting diodes, field effect transistors, and polymer solar cells.13 In our recent work on polymer solar cells, it was discovered that PFNOX can electrically dope PCBM and thus enables efficient electron transfer between the active layer and the interlayer of the polymer solar cell devices.12, 14 The excellent electron transfer characteristics and effective electrical doping of PFNOX to PCBM for polymer solar cells inspired us to use PFNOX as a polymer additive to electrically dope the PCBM ETL for PKSCs. It is expected that improved electron transport property of the PCBM upon PFNOX doping should benefit the performance of PKSCs. In this paper, we report an improved PCBM ETL that contains ≈95% of PCBM and two polymer additives, namely, PFNOX and polystyrene (PS), at very small weight percentages (1%–3%). As been demonstrated in our previous report,15 the function of the polystyrene (with a high molecular weight of 10 m kDa) additive is mainly to increase the viscosity of the ETL solution and thus improving the quality of the ETL films. The high film quality of the ETL also helps to suppress undesirable electron recombination caused by the defects in the ETL, which contributes to the increased Voc of the cell. In this paper, discussions will be mainly focused on the dramatic impacts of using PFNOX as the electrical dopant of the PCBM ETL. When neat PCBM or PCBM/PS are used as the ETL, the PKSCs exhibit large hysteresis and can only achieve PCE of ≈11%. With the additional PFNOX dopant, however, the PKSCs based on PCBM/PFNOX or PCBM/PFNOX/PS as the ETL exhibit dramatic improvements on cell performance with their PCEs increased to 14% and 16.2%, respectively. Most importantly and surprisingly, the cells based on ETL containing the PFNOX dopant exhibits dramatically reduced hysteresis. Our best cell with PCBM/(PFNOX&PS) ETL shows higher efficiency and negligible hysteresis, compared to the devices-based neat PCBM ETL. Combining the study of the transient photoluminescence (PL) and electrochemical impedance spectroscopy (EIS), it was found that the PFNOX doped PCBM ETL facilitates the electron injection from halide perovskite into the ETL and decreases the recombination rate of charge carriers. Our hybrid polymer/PCBM ETL offers a simple yet highly effective approach to improve the performance and reduce the hysteresis of PKSCs. The fundamental studies on the doped ETL also offer important insights on understanding the hysteresis problem and charge transfer and transport processes in PKSCs. The representative perovskite solar cell device with the structure of ITO/PEDOT:PSS/perovskite/PCBM:PFNOX/Ag is shown in Figure 1A. The chemical structure of PFNOX and PCBM are shown in Figure 1B. PFNOX is one of the best-performance example of the alkyl-amine-containing polyfluorene conjugated polymer family. In a typical PFNOX/PCBM hybrid ETL, there is only a small amount of (1.25 wt%) PFNOX in the PCBM layer. A PFNOX solution (5 mg mL−1) was added into a 20 mg mL−1 PCBM solution at a volume ratio of 1:20 and stirred overnight at 60 °C. The energy levels of the PCBM:PFNOX hybrid ETL are similar to those of the neat PCBM films, which are confirmed by the similar peaks in the UV–vis absorption spectra (Figure S1, Supporting Information) and cyclic voltammograms (Figure S2, Supporting Information) of the corresponding films. Figure 1C presents the typical cross-sectional scanning electron microscopy (SEM) image of a high performance photovoltaic device. A well-crystallized mixed halide perovskite (CH3NH3PbCl3−xIx) layer with a thickness of 450 nm is sandwiched between the PEDOT-PSS HTL and the PCBM: PFNOX ETL. Thus, a total thickness of the cell is ≈1 μm including a 200–300 nm ITO layer. To prove that the chlorine is homogeneously distributed in the perovskite layer, we show the SEM mapping, the enerdy dispersive X-ray spectroscopy (EDS) picture and element distribution (Figure S4 and Table S3, Supporting Information) of the perovskite layer. The data show that the chlorine ions are homogeneous and the chlorine only has small percentage in the MAPbCl3−xIx, which is in agreement with previous reports.15 The photocurrent density–voltage (J–V) characteristics measured under AM 1.5G irradiation at a one sun intensity of 100 mW cm−2 for cells with and without PFNOX additives are shown in Figure 2. The detailed performance parameters of these devices are summarized in Table 1. A typical device using the pure PCBM as the ETL can only achieve a PCE of ≈11.4%, with a short-circuit photocurrent (Jsc) 18.6 mA cm−2, an open-circuit voltage (Voc) of 0.952 and a fill factor (FF) of 0.668. However, when loading the PFNOX additive into the PCBM layer, the best performance has increased 14.0% with the Voc increasing to 0.94 V, Jsc increasing to 20.4 mA cm−2, and FF increasing to 0.729. This efficiency increase can be mainly attributed to the increases of the Jsc and FF. The incident photon-to-electron conversion efficiency (IPCE) spectrum is displayed in Figure 2B showing a remarkable increase of the integrated IPCE area upon PFNOX doping. In order to improve the uniformity of the PCBM ETL and further enhance the PCE performance, a second polymer additive, polystyrene (Mw ≈ 10 m), was included into the PCBM/PFNOX ETL. As shown in our previous report, the PS additive can increase the viscosity of the solution, thus improve the uniformity of the PCBM ETL.15, 16 As also shown in Figure 2A, the PS additive further increased the PCE of the PKSCs to an impressive value of 16.2%, with a Voc of 1.01 V, a Jsc of 20.8 mA cm−2, and a FF of 0.769. To check whether the high PCE of our devices is reliable, the stabilized photocurrent was measured at a photovoltage near the maximum power point of the optimal device. The photocurrent was then monitored and plotted as a function of time. As shown in Figure 2C, we obtained a steady-state PCE of 13.5% for PCBM:PFNOX-based device and 15.6% for that based on PCBM:(PFNOX&PS), thereby which is in agreement with the average PCE of the related devices. However, the PCBM only based device has a low PCE of 9.4%. For comparison, we also fabricated devices using the standard structure (FTO/TiO2/MAPbCl3−xIx/Spiro-OMeTAD/Ag) and obtained an efficiency of 14.5% (Table S5, Supporting Information). Hysteresis has been one of major problems for PKSCs, which could be attributed to grain boundaries and defects that cause strong recombination between the perovskite and charge transport layer.17 Several groups previously reported less-hysteresis effect for inverted planar heterojunction PKSCs with a structure of PEDOT:PSS/perovskite/PCBM.9, 18 One of the proposed reasons for the reduced hysteresis was the thermal passivation of the perovskite layer after long-term high temperature annealing, during which small molecular PCBM deposited onto the trap states of perovskite surface and eliminate the photocurrent hysteresis.1 Surface passivation is another approach to decrease the surface defects and reduce the recombination in the perovskite film.[18] In previous studies,[8],19 the fundamental causes of hysteresis have been attributed to several possible factors including grain boundaries in the perovskite films and charge-trapping defects at the perovskite and transport layer interfaces. Previous approaches were mainly focusing on improving the quality of perovskite layer by removing defects or growing large crystals. In contrast, our study focused on improving the PCBM electron transport layer. Figure 2D–F presents the three I–V curves for pure PCBM, PCBM:PFNOX, and PCBM: (PFNOX&PS) ETLs-based photovoltaic devices. For the PFNOX and PS codoped PCBM devices, they both show J–V curves with negligible hysteresis, with PCEs of 16.2% and 15.0% for the reverse and forward scans, respectively. We also performed the forward and reverse J–V scans at different rates and show that the performance is quite insensitive to the scan rates (Figure S5 and Table S4, Supporting Information). The negligible hysteresis is mainly attributed to PFNOX, as PCBM: PS devices (shown in Figure S3, Supporting Information) exhibit large hysteresis but PCBM: PFNOX shows negligible hysteresis. The pure PCBM-based solar devices also exhibit large hysteresis, which is due to the fast recombination by the surface trap states of perovskite films. As shown in a recent report, it is important to achieve balanced electron and hole transports in PKSCs to reduce hysteresis, our results clearly demonstrated that the electron transport ability of PCBM was a limiting factor in our PKSCs. By doping and improving the electron transport ability of the PCBM ETL, the performance of PKSCs can be dramatically enhanced. It is also reasonably to expect that our approach of improving the PCBM ETL can be combined with previous methods on improving the perovskite active layer, as faster electron transport should always be a desirable change for PKSCs. As PFNOX has been demonstrated to dope PCBM, it is reasonable to expect that the PFNOX doped PCBM can facilitate the electron transfer from the perovskite layer to the ETL layer and thus improving the cell performance. To prove this hypothesis, steady state, and transient PL spectroscopy were employed to study the charge carriers extraction process from the perovskite absorber to the PCBM layer.20 The steady state PL spectra of pure halide CH3NH3PbCl3−xIx perovskite and perovskite/ETL films are shown in Figure 3A. All of the samples exhibit a PL peak at 760 nm originated from the perovskite CH3NH3PbCl3−xIx. The PL intensity was largely quenched after the PCBM electron accepting layer coating. However, the extent of PL quenching is more significant for the perovskite sample with PCBM:PFNOX. The PL intensity of the PFNOX-doped PCBM sample decreased by 21 times compared to that of the perovskite sample, while the PL intensity decrease was ≈15 times for the nondoped PCBM sample. This observation indicates that PFNOX doping enables better charge separation from perovskite absorber to the ETL. We tested the electron mobility based on electron-only devices with the structure of ITO/ZnO/electron transport layer/Ca/Al. The J–V curves are shown in Figure 3B and the electrical parameters are summarized in Table S1 (Supporting Information). The result indicates that the electron transport ability of the PCBM:PFNOX is improved because PFNOX can effectively dope the PCBM ETL and thus enabling a greater electron transport ability. Also, our cyclic voltammetry and UV–vis measurements (Figures S1 and S2, Supporting Information) confirmed that the PFNOX-doped PCBM ETL has similar energy levels to the pure PCBM ETL. It is important to note that our study is distinctively different from previously reported hybrid perovskite/polymer solar cells,[6] which used a light-absorbing polymer:fullerene blend (≈50%:50% weight ratio) that contribute to the photo-current generation of the integrated cell. In our approach, the two polymers only account for 1–4 wt% in weight for the blend. In addition, the PFNOX polymer and polystyrene used in our study have very weak light-absorption properties (Figure S1, Supporting Information) in nature. They only function as low-concentration dopants to the PCBM ETL and do not contribute to the photo-current of the PKSCs. In this sense, the cells described in the previous report[6] are truly hybrid perovskite/polymer bulk-heterojunction (BHJ) solar cells, in which both the perovskite part and the polymer:fullerene BHJ film contribute to the photocurrent. However, our cells with PCBM:(PS&PFNOX) is still the typical inverted PKSCs that utilize a PCBM ETL with improved electron transport ability upon doping with two photo-inactive polymers. To examine the transfer process of free charges in these devices, we measured time-resolved PL spectroscopy directly on these solar cell devices for PCBM and PCBM:PFNOX-coated perovskite films. Figure 3C,D shows the decay traces of the emission peaks at 760 nm (1.63 eV) for the two devices with or without PFNOX at short-circuit and open-circuit conditions. More details for the measurement can be found in the Supporting Information and the fitting decay time is shown in Table S2 (Supporting Information). From these data, it is clear to conclude that the electron transfer from the perovskite to the ETL is faster for the PFNOX-doped PCBM-based than that for the neat PCBM-based devices, where the electron transfer rate of the PFNOX-based devices was ≈0.3 ns while that of the devices with neat PCBM was only ≈0.7 ns, suggesting PFNOX doping improves the electron transfer property. To further study the charge transfer process, especially the back recombination from ETL to perovskite layer, we measured devices under operating condition by EIS, which is often used to measure charge transfer and recombination parameters in solar cells, such as chemical capacitance, recombination resistance, charge conductivity, etc.21, 22Figure 4 presents Nyquist plots of the solar cells with PCBM: PFNOX (Figure 4A) and PCBM (Figure 4B) based devices, which were recorded at different applied voltages under 1-sun illumination. The frequency range for all of the EIS measurements is from 0.5 Hz to 1 MHz. All devices were applied a bias voltage ranging from 0 to 0.9 V as transport in the high frequency region would meet very small resistance, making it difficult to model the exact transport resistance value. The Nyquist plots typically can be demarked into two main regions or arcs at high and low frequencies. We fitted our data based on a commonly used equivalent circuit model shown in Figure 4E. Here, in the high frequency region, a transport resistance (Rtrans) with parallel chemical capacitance (Ctrans) subcircuit was applied. Then the arc in the low frequency region is assigned to the recombination resistance Rrec and the parallel chemical capacitance Crec. We introduce a recombination lifetime (Figure 4C) which combines the surface and bulk charge recombination lifetime. Here with the PFNOX doping, the recombinaion life time is much larger, almost one order of magnitude, than without PFNOX doping devices, which proves the recombination routes from PCBM back to perovskite is suppressed. We also calculated the transport mobility from high frequencies arc of the Nyquist plots in Figure 4D. Considering that the only variable factor is PFNOX, we can conclude that the improved tranport mobility is due to the PFNOX doping, as it has been demonstrated before that PFNOX can effectively dope PCBM12 and the doped PCBM apparently should exhibit a better charge transport ability than the nondoped counterpart.(also supported by our electron-only device results in Figure 3B). In summary, we have successfully developed a new polymer:PCBM hybrid ETL that is very simple yet appears to have dramatic impacts in improving the PCE and reducing the hysteresis of PKSCs. The PFNOX-doped devices exhibit a significant enhancement of short-circuit photocurrent (JSC) and PCE of 14.0% compared the PCE of 11.4% for devices without PFNOX. Furthermore, a second additive (polystyrene) was introduced to further increase the efficiency to 16.2% with negligible hysteresis. While the function of the polystyrene additive is to increase the film quality of the ETL, the reduced hysteresis is mainly attributed to the electrical doping of PFNOX to PCBM. Through time-resolved PL and EIS study, the improved PCE and reduced hysteresis are attributed to the faster electron transfer and reduced electron recombination for the PFNOX doped devices. Our work offers a simple and effective approach to addressing hysteresis problem for PKSCs. By combining our new ETL with existing approaches in the PKSC field, further improvement in PCE and hysteresis may be possible. This work was supported by the HK-RGC General Research Funds (HKUST 606511,605710, T23-407/13 N, N_HKUST623/13, and 606012), the National Basic Research Program of China (973 Program; 2013CB834701), the Ministry of Science and Technology (Grant Nos. 2014CB643505 and 2014CB643501), HK-ITF (ITS/004/14), HKUST president's office through SSTSP scheme (Project Ref No.: EP201), and the Natural Science Foundation of China (51323003, 51573057, 51361165301, and #21374090). K.S.W. would like to acknowledge the financial support of AoE/P-02/12 and CUHK1/CRF/12G from the Research Grants Council of Hong Kong. H.A. and B.R.G. would like to acknowledge the financial support of ONR grant N000141410531. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. DA - 2016/9// PY - 2016/9// DO - 10.1002/advs.201500353 VL - 3 IS - 9 SP - SN - 2198-3844 ER - TY - CONF TI - 10kv sic mps diodes for high temperature applications AU - Jiang, Y. F. AU - Sung, W. J. AU - Song, X. Q. AU - Ke, H. T. AU - Liu, S. Y. AU - Baliga, B. J. AU - Huang, A. Q. AU - Van Brunt, E. C2 - 2016/// C3 - 2016 28th international symposium on power semiconductor devices and ics (ispsd) DA - 2016/// SP - 43-46 ER - TY - JOUR TI - Unequal mass binary neutron star mergers and multimessenger signals AU - Lehner, Luis AU - Liebling, Steven L. AU - Palenzuela, Carlos AU - Caballero, O. L. AU - O'Connor, Evan AU - Anderson, Matthew AU - Neilsen, David T2 - CLASSICAL AND QUANTUM GRAVITY AB - We study the merger of binary neutron stars with different mass ratios adopting three different realistic, microphysical nuclear equations of state, as well as incorporating neutrino cooling effects. In particular, we concentrate on the influence of the equation of state on the gravitational wave signature and also on its role, in combination with neutrino cooling, in determining the properties of the resulting hypermassive neutron star, of the neutrinos produced, and of the ejected material. The ejecta we find are consistent with other recent studies that find that small mass ratios produce more ejecta than equal mass cases (up to some limit) and this ejecta is more neutron rich. This trend indicates the importance with future kilonovae observations of measuring the individual masses of an associated binary neutron star system, presumably from concurrent gravitational wave observations, in order to be able to extract information about the nuclear equation of state DA - 2016/9/22/ PY - 2016/9/22/ DO - 10.1088/0264-9381/33/18/184002 VL - 33 IS - 18 SP - SN - 1361-6382 KW - numerical relativity KW - gravitational waves KW - electromagnetic counterparts KW - multimessenger astronomy KW - binary neutron stars ER - TY - JOUR TI - Topological and geometric measurements of force-chain structure AU - Giusti, Chad AU - Papadopoulos, Lia AU - Owens, Eli T. AU - Daniels, Karen E. AU - Bassett, Danielle S. T2 - PHYSICAL REVIEW E AB - Developing quantitative methods for characterizing structural properties of force chains in densely packed granular media is an important step toward understanding or predicting large-scale physical properties of a packing. A promising framework in which to develop such methods is network science, which can be used to translate particle locations and force contacts to a graph in which particles are represented by nodes and forces between particles are represented by weighted edges. Applying network-based community-detection techniques to extract force chains opens the door to developing statistics of force chain structure, with the goal of identifying shape differences across packings, and providing a foundation on which to build predictions of bulk material properties from mesoscale network features. Here, we discuss a trio of related but fundamentally distinct measurements of mesoscale structure of force chains in arbitrary 2D packings, including a novel statistic derived using tools from algebraic topology, which together provide a tool set for the analysis of force chain architecture. We demonstrate the utility of this tool set by detecting variations in force chain architecture with pressure. Collectively, these techniques can be generalized to 3D packings, and to the assessment of continuous deformations of packings under stress or strain. DA - 2016/9/28/ PY - 2016/9/28/ DO - 10.1103/physreve.94.032909 VL - 94 IS - 3 SP - SN - 2470-0053 ER - TY - JOUR TI - The PROSPECT physics program AU - Ashenfelter, J. AU - Balantekin, A. B. AU - Band, H. R. AU - Barclay, G. AU - Bass, C. D. AU - Berish, D. AU - Bignell, L. AU - Bowden, N. S. AU - Bowes, A. AU - Brodsky, J. P. AU - Bryan, C. D. AU - Cherwinka, J. J. AU - Chu, R. AU - Classen, T. AU - Commeford, K. AU - Conant, A. J. AU - Davee, D. AU - Dean, D. T2 - Journal of Physics. G, Nuclear and Particle Physics DA - 2016/// PY - 2016/// VL - 43 IS - 11 ER - TY - JOUR TI - Prostate-associated gene 4 (PAGE4), an intrinsically disordered cancer/testis antigen, is a novel therapeutic target for prostate cancer AU - Kulkarni, Prakash AU - Dunker, A. Keith AU - Weninger, Keith AU - Orban, John T2 - ASIAN JOURNAL OF ANDROLOGY AB - Prostate-associated gene 4 (PAGE4) is a remarkably prostate-specific Cancer/Testis Antigen that is highly upregulated in the human fetal prostate and its diseased states but not in the adult normal gland. PAGE4 is an intrinsically disordered protein (IDP) that functions as a stress-response protein to suppress reactive oxygen species as well as prevent DNA damage. In addition, PAGE4 is also a transcriptional regulator that potentiates transactivation by the oncogene c-Jun. c-Jun forms the AP-1 complex by heterodimerizing with members of the Fos family and plays an important role in the development and pathology of the prostate gland, underscoring the importance of the PAGE4/c-Jun interaction. HIPK1, also a component of the stress-response pathway, phosphorylates PAGE4 at T51 which is critical for its transcriptional activity. Phosphorylation induces conformational and dynamic switching in the PAGE4 ensemble leading to a new cellular function. Finally, bioinformatics evidence suggests that the PAGE4 mRNA could be alternatively spliced resulting in four potential isoforms of the polypeptide alluding to the possibility of a range of conformational ensembles with latent functions. Considered together, the data suggest that PAGE4 may represent the first molecular link between stress and prostate cancer (PCa). Thus, pharmacologically targeting PAGE4 may be a novel opportunity for treating and managing patients with PCa, especially patients with low-risk disease. DA - 2016/9// PY - 2016/9// DO - 10.4103/1008-682x.181818 VL - 18 IS - 5 SP - 695-703 SN - 1745-7262 KW - prostate-associated Gene 4 KW - cancer/testis antigen KW - intrinsically disordered protein KW - prostate cancer KW - c-Jun KW - AP-1 KW - protein interaction networks KW - homeodomain-interacting protein 1 ER - TY - CONF TI - Oscillation degeneracy in non-standard neutrino interactions AU - Wright, W. AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Warren Wright; Oscillation degeneracy in non-standard neutrino interactions. AIP Conf. Proc. 21 June 2016; 1743 (1): 030010. https://doi.org/10.1063/1.4953291 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search C2 - 2016/// C3 - Cetup 2015 - workshop on dark matter, neutrino physics and astrophysics & ppc 2015 - ixth international conference on interconnections between particle physics and cosmology DA - 2016/// DO - 10.1063/1.4953291 VL - 1743 ER - TY - JOUR TI - Nonequilibrium all-atom molecular dynamics simulation of the bubble cavitation and application to dissociate amyloid fibrils AU - Viet, Man Hoang AU - Derreumaux, Philippe AU - Nguyen, Phuong H. T2 - JOURNAL OF CHEMICAL PHYSICS AB - The cavitation of gas bubbles in liquids has been applied to different disciplines in life and natural sciences, and in technologies. To obtain an appropriate theoretical description of effects induced by the bubble cavitation, we develop an all-atom nonequilibrium molecular-dynamics simulation method to simulate bubbles undergoing harmonic oscillation in size. This allows us to understand the mechanism of the bubble cavitation-induced liquid shear stress on surrounding objects. The method is then employed to simulate an Aβ fibril model in the presence of bubbles, and the results show that the bubble expansion and contraction exert water pressure on the fibril. This yields to the deceleration and acceleration of the fibril kinetic energy, facilitating the conformational transition between local free energy minima, and leading to the dissociation of the fibril. Our work, which is a proof-of-concept, may open a new, efficient way to dissociate amyloid fibrils using the bubble cavitation technique, and new venues to investigate the complex phenomena associated with amyloidogenesis. DA - 2016/11/7/ PY - 2016/11/7/ DO - 10.1063/1.4966263 VL - 145 IS - 17 SP - SN - 1089-7690 ER - TY - JOUR TI - Lowest energy Frenkel and charge transfer exciton intermixing in one-dimensional copper phthalocyanine molecular lattice AU - Bondarev, I. V. AU - Popescu, A. AU - Younts, R. A. AU - Hoffman, B. AU - McAfee, T. AU - Dougherty, D. B. AU - Gundogdu, K. AU - Ade, H. W. T2 - APPLIED PHYSICS LETTERS AB - We report the results of the combined experimental and theoretical studies of the low-lying exciton states in crystalline copper phthalocyanine. We derive the eigen energy spectrum for the two lowest intramolecular Frenkel excitons coupled to the intermolecular charge transfer exciton state and compare it with temperature dependent optical absorption spectra measured experimentally, to obtain the parameters of the Frenkel-charge-transfer exciton intermixing. The two Frenkel exciton states are spaced apart by 0.26 eV, and the charge transfer exciton state is 50 meV above the lowest Frenkel exciton. Both Frenkel excitons are strongly mixed with the charge transfer exciton, showing the coupling constant 0.17 eV which agrees with earlier experimental measurements. These results can be used for the proper interpretation of the physical properties of crystalline phthalocyanines. DA - 2016/11/21/ PY - 2016/11/21/ DO - 10.1063/1.4968821 VL - 109 IS - 21 SP - SN - 1077-3118 ER - TY - JOUR TI - Liquid gallium and the eutectic gallium indium (EGaIn) alloy: Dielectric functions from 1.24 to 3.1 eV by electrochemical reduction of surface oxides AU - Morales, Daniel AU - Stoute, Nicholas A. AU - Yu, Zhiyuan AU - Aspnes, David E. AU - Dickey, Michael D. T2 - APPLIED PHYSICS LETTERS AB - Liquid metals based on gallium are promising materials for soft, stretchable, and shape reconfigurable electromagnetic devices. The behavior of these metals relates directly to the thicknesses of their surface oxide layers, which can be determined nondestructively by ellipsometry if their dielectric functions ε are known. This paper reports on the dielectric functions of liquid gallium and the eutectic gallium indium (EGaIn) alloy from 1.24 to 3.1 eV at room temperature, measured by spectroscopic ellipsometry. Overlayer-induced artifacts, a continuing problem in optical measurements of these highly reactive metals, are eliminated by applying an electrochemically reductive potential to the surface of the metal immersed in an electrolyte. This technique enables measurements at ambient conditions while avoiding the complications associated with removing overlayers in a vacuum environment. The dielectric responses of both metals are closely represented by the Drude model. The EGaIn data suggest that in the absence of an oxide the surface is In-enriched, consistent with the previous vacuum-based studies. Possible reasons for discrepancies with previous measurements are discussed. DA - 2016/8/29/ PY - 2016/8/29/ DO - 10.1063/1.4961910 VL - 109 IS - 9 SP - SN - 1077-3118 ER - TY - CONF TI - Light-front quark model phenomenology consistent with chiral symmetry AU - Choi, H. M. AU - Ji, C. R. C2 - 2016/// C3 - 21st international conference on few-body problems in physics DA - 2016/// VL - 113 ER - TY - JOUR TI - Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films AU - Hoffman, Benjamin C. AU - McAfee, Terry AU - Conrad, Brad R. AU - Loth, Marsha A. AU - Anthony, John E. AU - Ade, Harald W. AU - Dougherty, Daniel B. T2 - ACS APPLIED MATERIALS & INTERFACES AB - Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge. DA - 2016/8/24/ PY - 2016/8/24/ DO - 10.1021/acsami.6b03886 VL - 8 IS - 33 SP - 21490-21496 SN - 1944-8244 KW - organic electronics KW - Kelvin probe force microscopy KW - charge traps KW - anthradithiophene KW - thin films ER - TY - JOUR TI - Generalized theory of diffusion based on kinetic theory AU - Schäfer, T. T2 - Phys.Rev.A AB - We propose to use spin hydrodynamics, a two-fluid model of spin propagation, as a generalization of the diffusion equation. We show that in the dense limit spin hydrodynamics reduces to Fick's law and the diffusion equation. In the opposite limit spin hydrodynamics is equivalent to a collisionless Boltzmann treatment of spin propagation. Spin hydrodynamics avoids unphysical effects that arise when the diffusion equation is used to describe to a strongly interacting gas with a dilute corona. We apply spin hydrodynamics to the problem of spin diffusion in a trapped atomic gas. We find that the observed spin relaxation rate in the high temperature limit [Sommer et al., Nature 472, 201 (2011)] is consistent with the diffusion constant predicted by kinetic theory. DA - 2016/10/26/ PY - 2016/10/26/ DO - 10.1103/PhysRevA.94.043644 VL - 94 IS - 4 SP - 043644 UR - http://inspirehep.net/record/1482387 ER - TY - JOUR TI - Fermi gases in the two-dimensional to quasi-two-dimensional crossover AU - Cheng, Chingyun AU - Kangara, J. AU - Arakelyan, I. AU - Thomas, J. E. T2 - PHYSICAL REVIEW A AB - We tune the dimensionality of pancake-shaped strongly-interacting $^6$Li Fermi gas clouds from two-dimensional (2D) to quasi-2D, by controlling the ratio of the radial Fermi energy $E_F$ to the harmonic oscillator energy $h\nu_z$ in the tightly confined direction. In the 2D regime, where $E_F<vol, h factor) database, taking into account patient size and scan coverage. The conversion coefficients have been previously estimated for routine body protocol classes, grouped by scan coverage, across an adult population for fixed tube current modulated CT. The coefficients, however, do not include the widely utilized tube current (mA) modulation scheme, which significantly impacts organ dose. This study aims to extend the h factors and the corresponding dose length product (DLP) to create effective dose conversion coefficients (k factor) database incorporating various tube current modulation strengths. Fifty-eight extended cardiac-torso (XCAT) phantoms were included in this study representing population anatomy variation in clinical practice. Four mA profiles, representing weak to strong mA dependency on body attenuation, were generated for each phantom and protocol class. A validated Monte Carlo program was used to simulate the organ dose. The organ dose and effective dose was further normalized by CTDIvol and DLP to derive the h factors and k factors, respectively. The h factors and k factors were summarized in an exponential regression model as a function of body size. Such a population-based mathematical model can provide a comprehensive organ dose estimation given body size and CTDIvol. The model was integrated into an iPhone app XCATdose version 2, enhancing the 1st version based upon fixed tube current modulation. With the organ dose calculator, physicists, physicians, and patients can conveniently estimate organ dose. DA - 2016/// PY - 2016/// DO - 10.1117/12.2217271 VL - 9783 SP - SN - 1996-756X KW - computed tomography KW - Monte Carlo KW - tube current modulation KW - organ dose KW - effective dose KW - iOS app ER - TY - JOUR TI - Neutrinos from type Ia supernovae: The deflagration-to-detonation transition scenario AU - Wright, Warren P. AU - Nagaraj, Gautam AU - Kneller, James P. AU - Scholberg, Kate AU - Seitenzahl, Ivo R. T2 - PHYSICAL REVIEW D AB - It has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear—type Ia—supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption of a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characteristic spectral peak at ∼10 MeV as a signature of electron captures on copper. This peak is a potentially distinguishing feature of explosion models since it reflects the nucleosynthesis conditions early in the explosion. We simulate the event rates in the Super-K, Hyper-K, JUNO, and DUNE neutrino detectors with the SNOwGLoBES event rate calculation software and also compute the IceCube signal. Hyper-K will be able to detect neutrinos from our model out to a distance of ∼10 kpc. At 1 kpc, JUNO, Super-K, and DUNE would register a few events while IceCube and Hyper-K would register several tens of events.22 MoreReceived 11 May 2016DOI:https://doi.org/10.1103/PhysRevD.94.025026© 2016 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasExplosive burningExtrasolar neutrino astronomyNeutrino interactionsNeutrino oscillationsNovae & supernovaeNuclear physics of explosive environmentsParticle astrophysicsPhysical SystemsNeutrinosStarsTechniquesAstrophysical & cosmological simulationsNeutrino detectorsGravitation, Cosmology & AstrophysicsParticles & Fields DA - 2016/7/19/ PY - 2016/7/19/ DO - 10.1103/physrevd.94.025026 VL - 94 IS - 2 SP - SN - 2470-0029 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84979671235&partnerID=MN8TOARS ER - TY - JOUR TI - Measurement of spin-flip probabilities for ultracold neutrons interacting with nickel phosphorus coated surfaces AU - Tang, Z. AU - Adamek, E. R. AU - Brandt, A. AU - Callahan, N. B. AU - Clayton, S. M. AU - Currie, S. A. AU - Ito, T. M. AU - Makela, M. AU - Masuda, Y. AU - Morris, C. L. AU - Pattie, R. W., Jr. AU - Ramsey, J. C. AU - Salvat, D. J. AU - Saunders, A. AU - Young, A. R. T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - We report a measurement of the spin-flip probabilities for ultracold neutrons interacting with surfaces coated with nickel phosphorus. For 50 μm thick nickel phosphorus coated on stainless steel, the spin-flip probability per bounce was found to be βNiPonSS=(3.3−5.6+1.8)×10−6. For 50 μm thick nickel phosphorus coated on aluminum, the spin-flip probability per bounce was found to be βNiPonAl=(3.6−5.9+2.1)×10−6. For the copper guide used as reference, the spin flip probability per bounce was found to be βCu=(6.7−2.5+5.0)×10−6. The results on the nickel phosphorus-coated surfaces may be interpreted as upper limits, yielding βNiPonSS<6.2×10−6 (90% C.L.) and βNiPonAl<7.0×10−6 (90% C.L.) for 50 μm thick nickel phosphorus coated on stainless steel and 50 μm thick nickel phosphorus coated on aluminum, respectively. Nickel phosphorus coated stainless steel or aluminum provides a solution when low-cost, mechanically robust, and non-depolarizing UCN guides with a high Fermi potential are needed. DA - 2016/8/11/ PY - 2016/8/11/ DO - 10.1016/j.nima.2016.04.098 VL - 827 SP - 32–38 SN - 1872-9576 KW - Ultracold neutron KW - Ultracold neutron guide KW - Spin depolarization KW - Nickel phosphorus ER - TY - JOUR TI - High refractive index immersion liquid for superresolution 3D imaging using sapphire-based aplanatic numerical aperture increasing lens optics AU - Laskar, Junaid M. AU - Kumar, P. Shravan AU - Herminghaus, Stephan AU - Daniels, Karen E. AU - Schroeter, Matthias T2 - APPLIED OPTICS AB - Optically transparent immersion liquids with refractive index (n∼1.77) to match the sapphire-based aplanatic numerical aperture increasing lens (aNAIL) are necessary for achieving deep 3D imaging with high spatial resolution. We report that antimony tribromide (SbBr3) salt dissolved in liquid diiodomethane (CH2I2) provides a new high refractive index immersion liquid for optics applications. The refractive index is tunable from n=1.74 (pure) to n=1.873 (saturated), by adjusting either salt concentration or temperature; this allows it to match (or even exceed) the refractive index of sapphire. Importantly, the solution gives excellent light transmittance in the ultraviolet to near-infrared range, an improvement over commercially available immersion liquids. This refractive-index-matched immersion liquid formulation has enabled us to develop a sapphire-based aNAIL objective that has both high numerical aperture (NA=1.17) and long working distance (WD=12 mm). This opens up new possibilities for deep 3D imaging with high spatial resolution. DA - 2016/4/20/ PY - 2016/4/20/ DO - 10.1364/ao.55.003165 VL - 55 IS - 12 SP - 3165-3169 SN - 2155-3165 ER - TY - JOUR TI - Fundamental limits of exciton-exciton annihilation for light emission in transition metal dichalcogenide monolayers AU - Yu, Y. L. AU - Yu, Y. F. AU - Xu, C. AU - Barrette, A. AU - gundogdu, AU - Cao, L. Y. T2 - Physical Review B AB - We quantitatively illustrate the fundamental limit that exciton-exciton annihilation (EEA) may impose to the light emission of monolayer transition metal dichalcogenide (TMDC) materials. The EEA in TMDC monolayers shows dependence on the interaction with substrates as its rate increases from 0.1 cm2/s (0.05 cm2/s) to 0.3 cm2/s (0.1 cm2/s) with the substrates removed for WS2 (MoS2) monolayers. It turns to be the major pathway of exciton decay and dominates the luminescence efficiency when the exciton density is beyond 1010 cm-2 in suspended monolayers or 1011 cm-2 in supported monolayers. This sets an upper limit on the density of injected charges in light emission devices for the realization of optimal luminescence efficiency. The strong EEA rate also dictates the pumping threshold for population inversion in the monolayers to be 12-18 MW/cm2 (optically) or 2.5-4x105 A/cm2 (electrically). DA - 2016/// PY - 2016/// DO - 10.1103/physrevb.93.201111 VL - 93 IS - 20 ER - TY - JOUR TI - Development of a Hausdorff Distance based 3D quantification technique to evaluate the CT imaging system impact on depiction of lesion morphology AU - Sahbaee, Pooyan AU - Robins, Marthony AU - Solomon, Justin AU - Samei, Ehsan T2 - MEDICAL IMAGING 2016: PHYSICS OF MEDICAL IMAGING AB - The purpose of this study was to develop a 3D quantification technique to assess the impact of imaging system on depiction of lesion morphology. Regional Hausdorff Distance (RHD) was computed from two 3D volumes: virtual mesh models of synthetic nodules or “virtual nodules” and CT images of physical nodules or “physical nodules”. The method can be described in following steps. First, the synthetic nodule was inserted into anthropomorphic Kyoto thorax phantom and scanned in a Siemens scanner (Flash). Then, nodule was segmented from the image. Second, in order to match the orientation of the nodule, the digital models of the “virtual” and “physical” nodules were both geometrically translated to the origin. Then, the “physical” was gradually rotated at incremental 10 degrees. Third, the Hausdorff Distance was calculated from each pair of “virtual” and “physical” nodules. The minimum HD value represented the most matching pair. Finally, the 3D RHD map and the distribution of RHD were computed for the matched pair. The technique was scalarized using the FWHM of the RHD distribution. The analysis was conducted for various shapes (spherical, lobular, elliptical, and speculated) of nodules. The calculated FWHM values of RHD distribution for the 8-mm spherical, lobular, elliptical, and speculated “virtual” and “physical” nodules were 0.23, 0.42, 0.33, and 0.49, respectively. DA - 2016/// PY - 2016/// DO - 10.1117/12.2216503 VL - 9783 SP - SN - 0277-786X KW - Computed Tomography KW - Lesion KW - 3D Quantification KW - Hausdorff Distance KW - Morphology ER - TY - JOUR TI - Development and Comparison of Projection and Image Space 3D Nodule Insertion Techniques AU - Robins, Marthony AU - Solomon, Justin AU - Sahbaee, Pooyan AU - Samei, Ehsan T2 - MEDICAL IMAGING 2016: PHYSICS OF MEDICAL IMAGING AB - This study aimed to develop and compare two methods of inserting computerized virtual lesions into CT datasets. 24 physical (synthetic) nodules of three sizes and four morphologies were inserted into an anthropomorphic chest phantom (LUNGMAN, KYOTO KAGAKU). The phantom was scanned (Somatom Definition Flash, Siemens Healthcare) with and without nodules present, and images were reconstructed with filtered back projection and iterative reconstruction (SAFIRE) at 0.6 mm slice thickness using a standard thoracic CT protocol at multiple dose settings. Virtual 3D CAD models based on the physical nodules were virtually inserted (accounting for the system MTF) into the nodule-free CT data using two techniques. These techniques include projection-based and image-based insertion. Nodule volumes were estimated using a commercial segmentation tool (iNtuition, TeraRecon, Inc.). Differences were tested using paired t-tests and R2 goodness of fit between the virtually and physically inserted nodules. Both insertion techniques resulted in nodule volumes very similar to the real nodules (<3% difference) and in most cases the differences were not statistically significant. Also, R2 values were all <0.97 for both insertion techniques. These data imply that these techniques can confidently be used as a means of inserting virtual nodules in CT datasets. These techniques can be instrumental in building hybrid CT datasets composed of patient images with virtually inserted nodules. DA - 2016/// PY - 2016/// DO - 10.1117/12.2216930 VL - 9783 SP - SN - 0277-786X KW - Computed Tomography KW - Lesion KW - 3D Quantification KW - Volume KW - Accuracy ER - TY - JOUR TI - Comparative melting and healing of B-DNA and Z-DNA by an infrared laser pulse AU - Man, Viet Hoang AU - Pan, Feng AU - Sagui, Celeste AU - Roland, Christopher T2 - JOURNAL OF CHEMICAL PHYSICS AB - We explore the use of a fast laser melting simulation approach combined with atomistic molecular dynamics simulations in order to determine the melting and healing responses of B-DNA and Z-DNA dodecamers with the same d(5'-CGCGCGCGCGCG-3')2 sequence. The frequency of the laser pulse is specifically tuned to disrupt Watson-Crick hydrogen bonds, thus inducing melting of the DNA duplexes. Subsequently, the structures relax and partially refold, depending on the field strength. In addition to the inherent interest of the nonequilibrium melting process, we propose that fast melting by an infrared laser pulse could be used as a technique for a fast comparison of relative stabilities of same-sequence oligonucleotides with different secondary structures with full atomistic detail of the structures and solvent. This could be particularly useful for nonstandard secondary structures involving non-canonical base pairs, mismatches, etc. DA - 2016/4/14/ PY - 2016/4/14/ DO - 10.1063/1.4945340 VL - 144 IS - 14 SP - SN - 1089-7690 ER - TY - JOUR TI - Comparative Structural and Computational Analysis Supports Eighteen Cellulose Synthases in the Plant Cellulose Synthesis Complex AU - Nixon, B. Tracy AU - Mansouri, Katayoun AU - Singh, Abhishek AU - Du, Juan AU - Davis, Jonathan K. AU - Lee, Jung-Goo AU - Slabaugh, Erin AU - Vandavasi, Venu Gopal AU - O'Neill, Hugh AU - Roberts, Eric M. AU - Roberts, Alison W. AU - Yingling, Yaroslava G. AU - Haigler, Candace H. T2 - SCIENTIFIC REPORTS AB - A six-lobed membrane spanning cellulose synthesis complex (CSC) containing multiple cellulose synthase (CESA) glycosyltransferases mediates cellulose microfibril formation. The number of CESAs in the CSC has been debated for decades in light of changing estimates of the diameter of the smallest microfibril formed from the β-1,4 glucan chains synthesized by one CSC. We obtained more direct evidence through generating improved transmission electron microscopy (TEM) images and image averages of the rosette-type CSC, revealing the frequent triangularity and average cross-sectional area in the plasma membrane of its individual lobes. Trimeric oligomers of two alternative CESA computational models corresponded well with individual lobe geometry. A six-fold assembly of the trimeric computational oligomer had the lowest potential energy per monomer and was consistent with rosette CSC morphology. Negative stain TEM and image averaging showed the triangularity of a recombinant CESA cytosolic domain, consistent with previous modeling of its trimeric nature from small angle scattering (SAXS) data. Six trimeric SAXS models nearly filled the space below an average FF-TEM image of the rosette CSC. In summary, the multifaceted data support a rosette CSC with 18 CESAs that mediates the synthesis of a fundamental microfibril composed of 18 glucan chains. DA - 2016/6/27/ PY - 2016/6/27/ DO - 10.1038/srep28696 VL - 6 SP - SN - 2045-2322 ER - TY - JOUR TI - Black hole spin influence on accretion disk neutrino detection AU - Caballero, O. L. AU - Zielinski, T. AU - McLaughlin, G. C. AU - Surman, R. T2 - PHYSICAL REVIEW D AB - Neutrinos are copiously emitted from black hole accretion disks playing a fundamental role in their evolution, as well as in the production of gamma ray bursts and r-process nucleosynthesis. The black hole generates a strong gravitational field able to change the properties of the emerging neutrinos. We study the influence of the black hole spin on the structure of the neutrino surfaces, neutrino luminosities, average neutrino energies, and event counts at SuperK. We consider several disk models and provide estimates that cover different black hole efficiency scenarios. We discuss the influence of the detector's inclination with respect to the axis of the torus on neutrino properties. We find that tori around spinning black holes have larger luminosities, energies and rates compared to tori around static black holes, and that the inclination of the observer causes a reduction in the luminosities and detection rates but an increase in the average energies. DA - 2016/6/22/ PY - 2016/6/22/ DO - 10.1103/physrevd.93.123015 VL - 93 IS - 12 SP - SN - 2470-0029 ER - TY - JOUR TI - AN X-RAY AND RADIO STUDY OF THE VARYING EXPANSION VELOCITIES IN TYCHO’S SUPERNOVA REMNANT AU - Williams, Brian J. AU - Chomiuk, Laura AU - Hewitt, John W. AU - Blondin, John M. AU - Borkowski, Kazimierz J. AU - Ghavamian, Parviz AU - Petre, Robert AU - Reynolds, Stephen P. T2 - The Astrophysical Journal AB - ABSTRACT We present newly obtained X-ray and radio observations of Tycho’s supernova remnant using Chandra and the Karl G. Jansky Very Large Array in 2015 and 2013/14, respectively. When combined with earlier epoch observations by these instruments, we now have time baselines for expansion measurements of the remnant of 12–15 years in the X-rays and 30 years in the radio. The remnant’s large angular size allows for proper motion measurements at many locations around the periphery of the blast wave. Consistent with earlier measurements, we find a clear gradient in the expansion velocity of the remnant, despite its round shape. The proper motions on the western and southwestern sides of the remnant are about a factor of two higher than those in the east and northeast. We showed in an earlier work that this is related to an offset of the explosion site from the geometric center of the remnant due to a density gradient in the ISM, and using our refined measurements reported here, we find that this offset is ∼23″ toward the northeast. An explosion center offset in such a circular remnant has implications for searches for progenitor companions in other remnants. DA - 2016/5/25/ PY - 2016/5/25/ DO - 10.3847/2041-8205/823/2/l32 VL - 823 IS - 2 SP - L32 J2 - ApJ OP - SN - 2041-8213 UR - http://dx.doi.org/10.3847/2041-8205/823/2/L32 DB - Crossref KW - dust, extinction KW - ISM: individual objects (Tycho's SNR) KW - ISM: supernova remnants ER - TY - JOUR TI - A technique for multi-dimensional optimization of radiation dose, contrast dose, and image quality in CT imaging AU - Sahbaee, Pooyan AU - Abadi, Ehsan AU - Sanders, Jeremiah AU - Becchetti, Marc AU - Zhang, Yakun AU - Agasthya, Greeshma AU - Segars, Paul AU - Samei, Ehsan T2 - MEDICAL IMAGING 2016: PHYSICS OF MEDICAL IMAGING AB - The purpose of this study was to substantiate the interdependency of image quality, radiation dose, and contrast material dose in CT towards the patient-specific optimization of the imaging protocols. The study deployed two phantom platforms. First, a variable sized phantom containing an iodinated insert was imaged on a representative CT scanner at multiple CTDI values. The contrast and noise were measured from the reconstructed images for each phantom diameter. Linearly related to iodine-concentration, contrast to noise ratio (CNR), was calculated for different iodine-concentration levels. Second, the analysis was extended to a recently developed suit of 58 virtual human models (5D-XCAT) with added contrast dynamics. Emulating a contrast-enhanced abdominal image procedure and targeting a peak-enhancement in aorta, each XCAT phantom was “imaged” using a CT simulation platform. 3D surfaces for each patient/size established the relationship between iodine-concentration, dose, and CNR. The Sensitivity of Ratio (SR), defined as ratio of change in iodine-concentration versus dose to yield a constant change in CNR was calculated and compared at high and low radiation dose for both phantom platforms. The results show that sensitivity of CNR to iodine concentration is larger at high radiation dose (up to 73%). The SR results were highly affected by radiation dose metric; CTDI or organ dose. Furthermore, results showed that the presence of contrast material could have a profound impact on optimization results (up to 45%). DA - 2016/// PY - 2016/// DO - 10.1117/12.2216516 VL - 9783 SP - SN - 1996-756X KW - Computed Tomography KW - Contrast Material KW - Compartmental Model KW - Contrast Enhanced KW - Patient Specific KW - Iodine KW - Radiation dose KW - CTDI KW - Image Quality ER - TY - JOUR TI - A direct correlation of x-ray diffraction orientation distributions to the in-plane stiffness of semi-crystalline organic semiconducting films AU - Zhao, Bingxiao AU - Awartani, Omar AU - O'Connor, Brendan AU - Zikry, Mohammed A. T2 - APPLIED PHYSICS LETTERS AB - Large charge mobilities of semi-crystalline organic semiconducting films could be obtained by mechanically aligning the material phases of the film with the loading axis. A key element is to utilize the inherent stiffness of the material for optimal or desired alignment. However, experimentally determining the moduli of semi-crystalline organic thin films for different loading directions is difficult, if not impossible, due to film thickness and material anisotropy. In this paper, we address these challenges by presenting an approach based on combining a composite mechanics stiffness orientation formulation with a Gaussian statistical distribution to directly estimate the in-plane stiffness (transverse isotropy) of aligned semi-crystalline polymer films based on crystalline orientation distributions obtained by X-ray diffraction experimentally at different applied strains. Our predicted results indicate that the in-plane stiffness of an annealing film was initially isotropic, and then it evolved to transverse isotropy with increasing mechanical strains. This study underscores the significance of accounting for the crystalline orientation distributions of the film to obtain an accurate understanding and prediction of the elastic anisotropy of semi-crystalline polymer films. DA - 2016/5/2/ PY - 2016/5/2/ DO - 10.1063/1.4948533 VL - 108 IS - 18 SP - SN - 1077-3118 ER - TY - JOUR TI - Uncovering the matter-neutrino resonance AU - Vaananen, D. AU - McLaughlin, G. C. T2 - PHYSICAL REVIEW D AB - Matter Neutrino Resonances (MNRs) can drastically modify neutrino flavor evolution in astrophysical environments and may significantly impact nucleosynthesis. Here we further investigate the underlying physics of MNR type flavor transitions. We provide generalized resonance conditions and make analytical predictions for the behavior of the system. We discuss the adiabatic evolution of these transitions, considering both Symmetric and Standard scenarios. Symmetric MNR transitions differ from Standard MNR transitions in that both neutrinos and antineutrinos can completely transform to other flavors simultaneously. We provide an example of the simplest system in which such transitions can occur with a neutrino and an antineutrino having a single energy and emission angle. We further apply linearized stability analysis to predict the location of self-induced nutation type (or bipolar) oscillations due to neutrino-neutrino interactions in the regions where MNR is ineffective. In all cases, we compare our analytical predictions to numerical calculations. DA - 2016/5/26/ PY - 2016/5/26/ DO - 10.1103/physrevd.93.105044 VL - 93 IS - 10 SP - SN - 2470-0029 ER - TY - JOUR TI - Time-Dependent Morphology Evolution of Solution-Processed Small Molecule Solar Cells during Solvent Vapor Annealing AU - Min, Jie AU - Jiao, Xuechen AU - Ata, Ibrahim AU - Osvet, Andres AU - Ameri, Tayebeh AU - Baeuerle, Peter AU - Ade, Harald AU - Brabec, Christoph J. T2 - ADVANCED ENERGY MATERIALS AB - Morphological modification using solvent vapor annealing (SVA) provides a simple and widely used fabrication option for improving the power conversion efficiencies of solution‐processed bulk heterojunction (BHJ) small molecule solar cells. Previous reports on SVA have shown that this strategy influences the degree of donor/acceptor phase separation and also improves molecular donor ordering. A blend composed of a dithienopyrrole containing oligothiophene as donor (named UU07) and [6,6]‐phenyl‐C61‐butyric acid methyl ester as acceptor is investigated with respect to SVA treatment to explore the dynamics of the BHJ evolution as a function of annealing time. A systematic study of the time dependence of morphology evolution clarifies the fundamental mechanisms behind SVA and builds the structure–property relation to the related device performance. The following two‐stage mechanism is identified: Initially, as SVA time increases, donor crystallinity is improved, along with enhanced domain purity resulting in improved charge transport properties and reduced recombination losses. However, further extending SVA time results in domains that are too large and a few large donor crystallites, depleting donor component in the mixed domain. Moreover, the larger domain microstructure suffers from enhanced recombination and overall lower bulk mobility. This not only reveals the importance of precisely controlling SVA time on gaining morphological control, but also provides a path toward rational optimization of device performance. DA - 2016/5/25/ PY - 2016/5/25/ DO - 10.1002/aenm.201502579 VL - 6 IS - 10 SP - SN - 1614-6840 ER - TY - JOUR TI - The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors AU - Hinton, J. P. AU - Thewalt, E. AU - Alpichshev, Z. AU - Mahmood, F. AU - Koralek, J. D. AU - Chan, M. K. AU - Veit, M. J. AU - Dorow, C. J. AU - Barišić, N. AU - Kemper, A. F. AU - Bonn, D. A. AU - Hardy, W. N. AU - Liang, Ruixing AU - Gedik, N. AU - Greven, M. AU - Lanzara, A. AU - Orenstein, J. T2 - Sci. Rep. AB - Abstract In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic ”pseudogap” phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature T c , suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τ qp , as a function of temperature and magnetic field in underdoped HgBa 2 CuO 4+ δ (Hg-1201) and YBa 2 Cu 3 O 6+ x (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τ qp ( T ) exhibits a local maximum in a small temperature window near T c that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that T c marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs. DA - 2016/4// PY - 2016/4// DO - 10.1038/srep23610 VL - 6 SP - 23610 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000373964900001&KeyUID=WOS:000373964900001 ER - TY - JOUR TI - The impact of individual nuclear properties on r-process nucleosynthesis AU - Mumpower, M. R. AU - Surman, R. AU - McLaughlin, G. C. AU - Aprahamian, A. T2 - PROGRESS IN PARTICLE AND NUCLEAR PHYSICS AB - The astrophysical rapid neutron capture process or ‘r process’ of nucleosynthesis is believed to be responsible for the production of approximately half the heavy element abundances found in nature. This multifaceted problem remains one of the greatest open challenges in all of physics. Knowledge of nuclear physics properties such as masses, β-decay and neutron capture rates, as well as β-delayed neutron emission probabilities are critical inputs that go into calculations of r-process nucleosynthesis. While properties of nuclei near stability have been established, much still remains unknown regarding neutron-rich nuclei far from stability that may participate in the r process. Sensitivity studies gauge the astrophysical response of a change in nuclear physics input(s) which allows for the isolation of the most important nuclear properties that shape the final abundances observed in nature. This review summarizes the extent of recent sensitivity studies and highlights how these studies play a key role in facilitating new insight into the r process. The development of these tools promotes a focused effort for state-of-the-art measurements, motivates construction of new facilities and will ultimately move the community toward addressing the grand challenge of ‘How were the elements from iron to uranium made?’. DA - 2016/1// PY - 2016/1// DO - 10.1016/j.ppnp.2015.09.001 VL - 86 SP - 86-126 SN - 1873-2224 KW - Binding energies and masses KW - r-process KW - Photonuclear reactions KW - Beta decay ER - TY - JOUR TI - The decay pattern of the Pygmy Dipole Resonance of Ce-140 AU - Loher, B. AU - Savran, D. AU - Aumann, T. AU - Beller, J. AU - Bhike, M. AU - Cooper, N. AU - Derya, V. AU - Duchene, M. AU - Endres, J. AU - Hennig, A. AU - Humby, P. AU - Isaak, J. AU - Kelley, J. H. AU - Knorzer, M. AU - Pietralla, N. AU - Ponomarev, V. Y. AU - Romig, C. AU - Scheck, M. AU - Scheit, H. AU - Silva, J. T2 - Physics Letters. B DA - 2016/// PY - 2016/// VL - 756 SP - 72-76 ER - TY - JOUR TI - The MAJORANA DEMONSTRATOR radioassay program AU - Abgrall, N. AU - Arnquist, I. J. AU - Avignone, F. T. AU - Back, H. O. AU - Barabash, A. S. AU - Bertrand, F. E. AU - Boswell, M. AU - Bradley, A. W. AU - Brudanin, V. AU - Busch, M. AU - Buuck, M. AU - Byram, D. AU - Caldwell, A. S. AU - Chan, Y. D. AU - Christofferson, C. D. AU - Chu, P. H. AU - Cuesta, C. T2 - Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors, and Associated Equipment DA - 2016/// PY - 2016/// VL - 828 SP - 22-36 ER - TY - JOUR TI - The Development of Explosions in Axisymmetricab Initio core-collapse Supernova Simulations of 12–25 M⊙ Stars AU - Bruenn, Stephen W. AU - Lentz, Eric J. AU - Hix, W. Raphael AU - Mezzacappa, Anthony AU - Harris, J. Austin AU - Messer, O. E. Bronson AU - Endeve, Eirik AU - Blondin, John M. AU - Chertkow, Merek Austin AU - Lingerfelt, Eric J. AU - Marronetti, Pedro AU - Yakunin, Konstantin N. T2 - The Astrophysical Journal AB - We present four ab initio axisymmetric core-collapse supernova simulations for 12, 15, 20, and 25 $M_\odot$ progenitors. All of the simulations yield explosions and have been evolved for at least 1.2 seconds after core bounce and 1 second after material first becomes unbound. Simulations were computed with our Chimera code employing spectral neutrino transport, special and general relativistic transport effects, and state-of-the-art neutrino interactions. Continuing the evolution beyond 1 second allows explosions to develop more fully and the processes powering the explosions to become more clearly evident. We compute explosion energy estimates, including the binding energy of the stellar envelope outside the shock, of 0.34, 0.88, 0.38, and 0.70 B ($10^{51}$ ergs) and increasing at 0.03, 0.15, 0.19, and 0.52 B s$^{-1}$, respectively, for the 12, 15, 20, and 25 $M_\odot$ models. Three models developed pronounced prolate shock morphologies, while the 20 $M_\odot$ model, though exhibiting lobes and accretion streams like the other models, develops an approximately spherical, off-center shock as the explosion begins and then becomes moderately prolate $\sim$600 ms after bounce. This reduces the explosion energy relative to the other models by reducing mass accretion during the critical explosion power-up phase. We examine the growth of the explosion energy in our models through detailed analyses of the energy sources and flows. We find that the 12 and 20 $M_\odot$ models have explosion energies comparable to that of the lower range of observed explosion energies while the 15 and 25 $M_\odot$ models are within the range of observed explosion energies, particularly considering the rate at which their explosion energies are increasing. The ejected $^{56}$Ni masses given by our models are all within observational limits as are the proto-neutron star masses and kick velocities. (Truncated) DA - 2016/2/16/ PY - 2016/2/16/ DO - 10.3847/0004-637x/818/2/123 VL - 818 IS - 2 SP - 123 SN - 1538-4357 UR - http://dx.doi.org/10.3847/0004-637X/818/2/123 KW - abundances KW - neutrinos KW - nuclear reactions KW - nucleosynthesis KW - stars: evolution KW - stars: massive KW - supernovae: general ER - TY - JOUR TI - Supramolecular clusters and chains of 2,6-dimethylpyridine on Cu(110): Observation of dynamic configuration change with real-space surface science techniques and DFT calculations AU - Lee, Junseok AU - Sorescu, Dan C. AU - Lee, Jae-Gook AU - Dougherty, Dan T2 - SURFACE SCIENCE AB - The adsorption of 2,6-dimethylpyridine (2,6-DMP) on Cu(110) has been studied using low temperature scanning tunneling microscopy (LT-STM), time-of-flight electron stimulated desorption ion angular distribution (TOF-ESDIAD), and density functional theory (DFT) calculations. At low temperatures (T < ~ 150 K), the 2,6-DMP adsorbs in a flat configuration on Cu(110) producing clusters and extended domains via weak hydrogen bonding (C—H···N) with the molecular symmetry axis aligned along the < 001 > surface direction. At near-saturation coverage, a c(6 × 2) long-range ordered structure was observed. Upon annealing to T = 200 K, the 2,6-DMP molecules adopt an upright configuration with their pyridine ring plane oriented parallel to the <11̅0> azimuth. These upright 2,6-DMP molecules produce extended molecular chains where the repulsive interactions between the molecular chains give rise to coverage-dependent interchain distances. At near-saturation coverage, a 1260 surface structure is observed for the upright configuration. The DFT calculations suggest that the Cu adatom plays an important role in the adsorption configuration change of the 2,6-DMP molecule. DA - 2016/10// PY - 2016/10// DO - 10.1016/j.susc.2016.01.020 VL - 652 SP - 82-90 SN - 1879-2758 KW - Adatom KW - Hydrogen bonding KW - Nanostructure KW - Self-assembly KW - STM KW - DFT ER - TY - JOUR TI - Intrinsic coincident linear polarimetry using stacked organic photovoltaics AU - Roy, S. Gupta AU - Awartani, O. M. AU - Sen, P. AU - O'Connor, B. T. AU - Kudenov, M. W. T2 - OPTICS EXPRESS AB - Polarimetry has widespread applications within atmospheric sensing, telecommunications, biomedical imaging, and target detection. Several existing methods of imaging polarimetry trade off the sensor's spatial resolution for polarimetric resolution, and often have some form of spatial registration error. To mitigate these issues, we have developed a system using oriented polymer-based organic photovoltaics (OPVs) that can preferentially absorb linearly polarized light. Additionally, the OPV cells can be made semitransparent, enabling multiple detectors to be cascaded along the same optical axis. Since each device performs a partial polarization measurement of the same incident beam, high temporal resolution is maintained with the potential for inherent spatial registration. In this paper, a Mueller matrix model of the stacked OPV design is provided. Based on this model, a calibration technique is developed and presented. This calibration technique and model are validated with experimental data, taken with a cascaded three cell OPV Stokes polarimeter, capable of measuring incident linear polarization states. Our results indicate polarization measurement error of 1.2% RMS and an average absolute radiometric accuracy of 2.2% for the demonstrated polarimeter. DA - 2016/6/27/ PY - 2016/6/27/ DO - 10.1364/oe.24.014737 VL - 24 IS - 13 SP - 14737-14747 SN - 1094-4087 ER - TY - JOUR TI - Engineering Substrate Interactions for High Luminescence Efficiency of Transition-Metal Dichalcogenide Monolayers AU - Yu, Yifei AU - Yu, Yiling AU - Xu, Chao AU - Cai, Yong-Qing AU - Su, Liqin AU - Zhang, Yong AU - Zhang, Yong-Wei AU - Gundogdu, Kenan AU - Cao, Linyou T2 - ADVANCED FUNCTIONAL MATERIALS AB - It is demonstrated that the luminescence efficiency of monolayers composed of MoS 2 , WS 2 , and WSe 2 is significantly limited by the substrate and can be improved by orders of magnitude through substrate engineering. The substrate affects the efficiency mainly through doping the monolayers and facilitating defect‐assisted nonradiative exciton recombinations, while the other substrate effects including straining and dielectric screening play minor roles. The doping may come from the substrate and substrate‐borne water moisture, the latter of which is much stronger than the former for MoS 2 and WS 2 but negligible for WSe 2 . Using proper substrates such as mica or hexagonal boron nitride can substantially mitigate the doping effect. The defect‐assisted recombination depends on the interaction between the defect in the monolayer and the substrate. Suspended monolayers, in which the substrate effects are eliminated, may have efficiency up to 40% at room temperatures. The result provides useful guidance for the rational design of atomic‐scale light emission devices. DA - 2016/7/12/ PY - 2016/7/12/ DO - 10.1002/adfm.201600418 VL - 26 IS - 26 SP - 4733-4739 SN - 1616-3028 ER - TY - JOUR TI - Comparative Photovoltaic Study of Physical Blending of Two Donor-Acceptor Polymers with the Chemical Blending of the Respective Moieties AU - Zhang, Qianqian AU - Kelly, Mary Allison AU - Hunt, Adrian AU - Ade, Harald AU - You, Wei T2 - MACROMOLECULES AB - A regularly alternating terpolymer and a random terpolymer were synthesized from the constituent units of two donor–acceptor polymers with complementary absorption. They were then compared to a physical blend of these two donor–acceptor polymers in order to investigate the best means of extending the light absorption range in bulk heterojunction (BHJ) solar cells. While all three methods broadened the light absorption, the physical blend provided the best improvement in power conversion efficiency (4.10% vs 3.63% and 2.67% for the random and regular terpolymers, respectively). This is due to the increase in aggregation in the physical blend, as demonstrated in the UV–vis spectra, which likely leads to higher local mobility and less recombination. This study shows that in order to effectively increase the light absorption (and therefore performance) of a polymer:fullerene based BHJ solar cell, a terpolymer must retain a structure which allows sufficient aggregation. DA - 2016/4/12/ PY - 2016/4/12/ DO - 10.1021/acs.macromol.5b02586 VL - 49 IS - 7 SP - 2533-2540 SN - 1520-5835 ER - TY - JOUR TI - Atomically Thin MoS2 Narrowband and Broadband Light Superabsorbers AU - Huang, Lujun AU - Li, Guoqing AU - Gurarslan, Alper AU - Yu, Yiling AU - Kirste, Ronny AU - Guo, Wei AU - Zhao, Junjie AU - Collazo, Ramon AU - Sitar, Zlatko AU - Parsons, Gregory N. AU - Kudenov, Michael AU - Cao, Linyou T2 - ACS NANO AB - We present a combined theoretical and experimental effort to enable strong light absorption (>70%) in atomically thin MoS2 films (≤4 layers) for either narrowband incidence with arbitrarily prespecified wavelengths or broadband incidence like solar radiation. This is achieved by integrating the films with resonant photonic structures that are deterministically designed using a unique reverse design approach based on leaky mode coupling. The design starts with identifying the properties of leaky modes necessary for the targeted strong absorption, followed by searching for the geometrical features of nanostructures to support the desired modes. This process is very intuitive and only involves a minimal amount of computation, thanks to the straightforward correlations between optical functionality and leaky modes as well as between leaky modes and the geometrical feature of nanostructures. The result may provide useful guidance for the development of high-performance atomic-scale photonic devices, such as solar cells, modulators, photodetectors, and photocatalysts. DA - 2016/8// PY - 2016/8// DO - 10.1021/acsnano.6b02195 VL - 10 IS - 8 SP - 7493-7499 SN - 1936-086X KW - MoS2 KW - two-dimensional materials KW - light absorption KW - leaky mode KW - resonant photonics ER - TY - JOUR TI - The impact of individual nuclear properties on r-process nucleosynthesis (vol 86C, pg 86, 2015) AU - Mumpower, M. R. AU - Surman, R. AU - McLaughlin, G. C. AU - Aprahamian, A. T2 - PROGRESS IN PARTICLE AND NUCLEAR PHYSICS DA - 2016/3// PY - 2016/3// DO - 10.1016/j.ppnp.2015.12.002 VL - 87 SP - 116-116 SN - 1873-2224 ER - TY - JOUR TI - Temperature-Dependent Hypersonic Flow Patterns of Expanding High-Density Metal Vapor Plasma from Capillary Source Simulating Plasma Flow Following a Fusion Disruption AU - Majumdar, Rudrodip AU - Bourham, Mohamed T2 - JOURNAL OF FUSION ENERGY DA - 2016/4// PY - 2016/4// DO - 10.1007/s10894-015-0027-0 VL - 35 IS - 2 SP - 312-326 SN - 1572-9591 KW - Electrothermal plasma expansion KW - Metal vapor plasma KW - Adiabatic compressibility index KW - Fusion disruption KW - PFC disruption KW - Particulate expansion ER - TY - JOUR TI - THE SENSITIVITY OF CORE-COLLAPSE SUPERNOVAE TO NUCLEAR ELECTRON CAPTURE AU - Sullivan, Chris AU - O'Connor, Evan AU - Zegers, Remco G. T. AU - Grubb, Thomas AU - Austin, Sam M. T2 - ASTROPHYSICAL JOURNAL AB - A weak-rate library aimed at investigating the sensitivity of astrophysical environments to variations of electron-capture rates on medium-heavy nuclei has been developed. With this library, the sensitivity of the core-collapse and early post-bounce phases of core-collapse supernovae to nuclear electron-capture is examined by systematically and statistically varying electron-capture rates of individual nuclei. The rates are adjusted by factors consistent with uncertainties indicated by comparing theoretical rates to those deduced from charge-exchange and $\beta$-decay measurements. To ensure a model independent assessment, sensitivity studies across a comprehensive set of progenitors and equations of state are performed. In our systematic study, we find a +16/-4 % range in the mass of the inner-core at the time of shock formation and a $\pm$20% range of peak {\nu}e-luminosity during the deleptonization burst. These ranges are each five times as large as those seen from a separate progenitor study in which we evaluated the sensitivity of these parameters to 32 presupernova stellar models. It is also found that the simulations are more sensitive to a reduction in the electron-capture rates than an enhancement, and in particular to the reduction in the rates for neutron-rich nuclei near the N = 50 closed neutron-shell. As measurements for medium-heavy (A > 65) and neutron-rich nuclei are sparse, and because accurate theoretical models which account for nuclear structure considerations on the individual nucleus level are not readily available, rates for these nuclei may be overestimated. If more accurate estimates confirm this, results from this study indicate that significant changes to the core-collapse trajectory can be expected. For this reason, experimental and theoretical efforts should focus in this region of the nuclear chart. DA - 2016/1/1/ PY - 2016/1/1/ DO - 10.3847/0004-637x/816/1/44 VL - 816 IS - 1 SP - SN - 1538-4357 KW - neutrinos KW - nuclear reactions, nucleosynthesis, abundances KW - equation of state KW - supernovae: general ER - TY - JOUR TI - THE MULTI-DIMENSIONAL CHARACTER OF CORE-COLLAPSE SUPERNOVAE AU - Hix, W. R. AU - Lentz, E. J. AU - Bruenn, S. W. AU - Mezzacappa, A. AU - Messer, O. E. B. AU - Endeve, E. AU - Blondin, J. M. AU - Harris, J. A. AU - Marronetti, P. AU - Yakunin, K. N. AU - al., T2 - ACTA PHYSICA POLONICA B AB - Core-collapse supernovae, the culmination of massive stellar evolution, are spectacular astronomical events and the principle actors in the story of our elemental origins. Our understanding of these events, while still incomplete, centers around a neutrino-driven central engine that is highly hydrodynamically unstable. Increasingly sophisticated simulations reveal a shock that stalls for hundreds of milliseconds before reviving. Though brought back to life by neutrino heating, the development of the supernova explosion is inextricably linked to multi-dimensional fluid flows. In this paper, the outcomes of three-dimensional simulations that include sophisticated nuclear physics and spectral neutrino transport are juxtaposed to learn about the nature of the three dimensional fluid flow that shapes the explosion. Comparison is also made between the results of simulations in spherical symmetry from several groups, to give ourselves confidence in the understanding derived from this juxtaposition. DA - 2016/3// PY - 2016/3// DO - 10.5506/aphyspolb.47.645 VL - 47 IS - 3 SP - 645-657 SN - 1509-5770 ER - TY - JOUR TI - SECOND EPOCH HUBBLE SPACE TELESCOPE OBSERVATIONS OF KEPLER'S SUPERNOVA REMNANT: THE PROPER MOTIONS OF BALMER FILAMENTS AU - Sankrit, Ravi AU - Raymond, John C. AU - Blair, William P. AU - Long, Knox S. AU - Williams, Brian J. AU - Borkowski, Kazimierz J. AU - Patnaude, Daniel J. AU - Reynolds, Stephen P. T2 - ASTROPHYSICAL JOURNAL AB - ABSTRACT We report on the proper motions of Balmer-dominated filaments in Kepler’s supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of 5.1 0.7 + 0.8 ?> kpc. The main shock around the northern rim of the remnant has a typical speed of 1690 km s −1 and is encountering material with densities of about 8 cm −3 . We find evidence for the variation of shock properties over small spatial scales, including differences in the driving pressures as the shock wraps around a curved cloud surface. We find that the Balmer filaments ahead of the ejecta knot on the northwest boundary of the remnant are becoming fainter and more diffuse. We also find that the Balmer filaments associated with circumstellar material in the interior regions of the remnant are due to shocks with significantly lower velocities and that the brightness variations among these filaments trace the density distribution of the material, which may have a disk-like geometry. DA - 2016/1/20/ PY - 2016/1/20/ DO - 10.3847/0004-637x/817/1/36 VL - 817 IS - 1 SP - SN - 1538-4357 UR - https://doi.org/10.3847/0004-637X/817/1/36 KW - ISM: individual objects (Kepler SN 1604, G4.5+6.8) KW - ISM: supernova remnants ER - TY - JOUR TI - Resonance-Enhanced Raman Scattering of Ring-Involved Vibrational Modes in the B-1(2u) Absorption Band of Benzene, Including the Kekule Vibrational Modes nu(9) and nu(10) AU - Willitsford, Adam H. AU - Chadwick, C. Todd AU - Kurtz, Stewart AU - Philbrick, C. Russell AU - Hallen, Hans T2 - JOURNAL OF PHYSICAL CHEMISTRY A AB - Resonance Raman spectroscopy provides much stronger Raman signal levels than its off-resonant counterpart and adds selectivity by excitation tuning. Raman preresonance of benzene has been well studied. On-resonance studies, especially at phonon-allowed absorptions, have received less attention. In this case, we observe resonance of many of the vibration modes associated motion of the carbons in the ring while tuning over the (1)B2u absorption, including the related ν9 (CC stretch Herzberg notation, ν14 Wilson notation) and ν10 (CH-parallel bend Herzberg notation, ν15 Wilson notation) vibrational modes along with the ν2 (CC-stretch or ring-breathing Herzberg notation, ν1 Wilson notation) mode and multiples of the ν18 (CCC-parallel bend Herzberg notation, ν6 Wilson notation) vibrational mode. The ring-breathing mode is found to mix with the b2u modes creating higher frequency composites. Through the use of an optical parametric oscillator (OPO) to tune through the (1)B2u absorption band of liquid benzene, a stiffening (increase in energy) of the vibrational modes is observed as the excitation wavelength nears the (1)B2u absorption peak of the isolated molecule (vapor) phase. The strongest resonance amplitude observed is in the 2 × ν18 (e2g) mode, with nearly twice the intensity of the ring-breathing mode, ν2. Several overtones and combination modes, especially with ν2 (a1g), are also observed to resonate. Raman resonances on phonon-allowed excitations are narrow and permit the measurement of vibrations not Raman-active in the ground state. DA - 2016/2/4/ PY - 2016/2/4/ DO - 10.1021/acs.jpca.5b08159 VL - 120 IS - 4 SP - 503-506 SN - 1520-5215 UR - http://dx.doi.org/10.1021/acs.jpca.5b08159 ER - TY - JOUR TI - Neutron-antineutron oscillations: Theoretical status and experimental prospects AU - Phillips, D. G., II AU - Snow, W. M. AU - Babul, K. AU - Banerjee, S. AU - Baxter, D. V. AU - Berezhiani, Z. AU - Bergevin, M. AU - Bhattacharya, S. AU - Brooijmans, G. AU - Castellanos, L. AU - Chen, M. -C. AU - Coppola, C. E. AU - Cowsik, R. AU - Crabtree, J. A. AU - Das, P. AU - Dees, E. B. AU - Dolgov, A. AU - Ferguson, P. D. AU - Frost, M. AU - Gabrie, T. AU - Gal, A. AU - Gallmeier, F. AU - Ganezer, K. AU - Golubeva, E. AU - Greene, G. AU - Hartfiel, B. AU - Hawari, A. AU - Heilbronn, L. AU - Johnson, C. AU - Kamyshkov, Y. AU - Kerbikov, B. AU - Kitaguchi, M. AU - Kopeliovich, B. Z. AU - Kopeliovich, V. B. AU - Kuzmin, V. A. AU - Liu, C. -Y. AU - McGaughey, P. AU - Mocko, M. AU - Mohapatra, R. AU - Mokhov, N. AU - Muhrer, G. AU - Mumm, H. P. AU - Okun, L. AU - Pattie, R. W., Jr. AU - Quigg, C. AU - Ramberg, E. AU - Ray, A. AU - Roy, A. AU - Ruggles, A. AU - Sarkar, U. AU - Saunders, A. AU - Serebrov, A. P. AU - Shimizu, H. M. AU - Shrock, R. AU - Sikdar, A. K. AU - Sjue, S. AU - Striganov, S. AU - Townsend, L. W. AU - Tschirhart, R. AU - Vainshtein, A. AU - Van Kooten, R. AU - Wang, Z. AU - Young, A. R. T2 - PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS AB - The observation of neutrons turning into antineutrons would constitute a discovery of fundamental importance for particle physics and cosmology. Observing the n–n̄ transition would show that baryon number (B) is violated by two units and that matter containing neutrons is unstable. It would provide a clue to how the matter in our universe might have evolved from the B=0 early universe. If seen at rates observable in foreseeable next-generation experiments, it might well help us understand the observed baryon asymmetry of the universe. A demonstration of the violation of B–L by 2 units would have a profound impact on our understanding of phenomena beyond the Standard Model of particle physics. Slow neutrons have kinetic energies of a few meV. By exploiting new slow neutron sources and optics technology developed for materials research, an optimized search for oscillations using free neutrons from a slow neutron moderator could improve existing limits on the free oscillation probability by at least three orders of magnitude. Such an experiment would deliver a slow neutron beam through a magnetically-shielded vacuum chamber to a thin annihilation target surrounded by a low-background antineutron annihilation detector. Antineutron annihilation in a target downstream of a free neutron beam is such a spectacular experimental signature that an essentially background-free search is possible. An authentic positive signal can be extinguished by a very small change in the ambient magnetic field in such an experiment. It is also possible to improve the sensitivity of neutron oscillation searches in nuclei using large underground detectors built mainly to search for proton decay and detect neutrinos. This paper summarizes the relevant theoretical developments, outlines some ideas to improve experimental searches for free neutron oscillations, and suggests avenues both for theoretical investigation and for future improvement in the experimental sensitivity. DA - 2016/2/11/ PY - 2016/2/11/ DO - 10.1016/j.physrep.2015.11.001 VL - 612 SP - 1-45 SN - 1873-6270 KW - Neutron-antineutron oscillation KW - Baryon number violation KW - Spallation KW - Cold neutron source KW - Quasi-free condition ER - TY - JOUR TI - Microstructural Behavior and Failure Mechanisms of Organic Semicrystalline Thin Film Blends AU - Zhao, Bingxiao AU - Awartani, Omar AU - O'Connor, Brendan AU - Zikry, Mohammed A. T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Organic thin film blends of P3HT semiconducting polymers and PCBM fullerenes have enabled large-scale semiconductor fabrication pertaining to flexible and stretchable electronics. However, molecular packing and film morphologies can significantly alter mechanical stability and failure behavior. To further understand and identify the fundamental mechanisms affecting failure, a multiphase microstructurally based formulation and nonlinear finite-element fracture methodology were used to investigate the heterogeneous deformation and failure modes of organic semicrystalline thin film blends. The multiphase formulation accounts for the crystalline and amorphous behavior, polymer tie-chains, and the PCBM aggregates. Face-on packing orientations resulted in extensive inelastic deformation and crystalline rotation, and this was characterized by ductile failure modes and interfacial delamination. For edge-on packing orientations, brittle failure modes and film cracking were due to lower inelastic deformation and higher film stress in comparison with the face-on orientations. The higher crystallinity of P3HT and larger PCBM aggregates associated with larger domain sizes, strengthened the film and resulted in extensive film cracking. These predictions of ductile and brittle failure are consistent with experimental observations for P3HT:PCBM films. The proposed predictive framework can be used to improve organic film ductility and strength through the control of molecular packing orientations and microstructural mechanisms. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 896–907 DA - 2016/5/1/ PY - 2016/5/1/ DO - 10.1002/polb.23991 VL - 54 IS - 9 SP - 896-907 SN - 1099-0488 KW - flexible material systems KW - interfacial delamination KW - microstructural failure mechanisms KW - modeling KW - organic thin films KW - P3HT: PCBM ER - TY - JOUR TI - Charged vanadium-benzene multidecker clusters: DFT and quantum Monte Carlo study AU - Tokar, K. AU - Derian, R. AU - Mitas, L. AU - Stich, I. T2 - JOURNAL OF CHEMICAL PHYSICS AB - Using explicitly correlated fixed-node quantum Monte Carlo and density functional theory (DFT) methods, we study electronic properties, ground-state multiplets, ionization potentials, electron affinities, and low-energy fragmentation channels of charged half-sandwich and multidecker vanadium-benzene systems with up to 3 vanadium atoms, including both anions and cations. It is shown that, particularly in anions, electronic correlations play a crucial role; these effects are not systematically captured with any commonly used DFT functionals such as gradient corrected, hybrids, and range-separated hybrids. On the other hand, tightly bound cations can be described qualitatively by DFT. A comparison of DFT and quantum Monte Carlo provides an in-depth understanding of the electronic structure and properties of these correlated systems. The calculations also serve as a benchmark study of 3d molecular anions that require a balanced many-body description of correlations at both short- and long-range distances. DA - 2016/2/14/ PY - 2016/2/14/ DO - 10.1063/1.4941085 VL - 144 IS - 6 SP - SN - 1089-7690 ER - TY - JOUR TI - Charge photogeneration in organic photovoltaics: Role of hot versus cold charge-transfer excitons AU - Gautam, B. R. AU - Younts, R. AU - Li, W. T. AU - Yan, L. AU - Danilov, E. AU - Klump, E. AU - Constantinou, I. AU - So, Franky AU - You, W. AU - Ade, Harald AU - gundogdu, T2 - Advanced Energy Materials AB - In article number 1501032, Kenan Gundogdu and co-workers present hot and cold exciton charge separation at the polymer/fullerene interface. On the left of the image high energy photons create excitons with excess energy. On the right of the image low energy photons create solely low energy charge transfer excitons. Both types separate into free charges effectively. DA - 2016/// PY - 2016/// DO - 10.1002/aenm.201670002 VL - 6 IS - 1 ER - TY - JOUR TI - Characterization of a B-10-doped liquid scintillator as a capture-gated neutron spectrometer AU - Hunt, S. AU - Iliadis, C. AU - Longland, R. T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - We use a 250 MHz digitizer to characterize the pulse shape discrimination of a BC-523A 10B-doped liquid scintillator with capture-gating capabilities. Our results are compared to recent work claiming pulse shape discrimination between fast and thermal neutron signals. The capture event is identified, and we explain the origin of signals that are often misinterpreted. We use the time-of-flight method to measure the detector energy resolution for fast incident monoenergetic neutrons and the intrinsic neutron detection efficiency. Monte Carlo simulations are performed and we find agreement between measured and simulated results. These steps are important for understanding 10B-doped capture-gated spectroscopy in mixed radiation environments, as efficiencies using capture-gating are rarely reported in the literature. DA - 2016/3/1/ PY - 2016/3/1/ DO - 10.1016/j.nima.2015.12.001 VL - 811 SP - 108-114 SN - 1872-9576 KW - Capture-gated detector KW - Pulse shape discrimination KW - Liquid scintillator KW - Neutron spectroscopy KW - Intrinsic neutron detection efficiency KW - Fast neutron energy resolution ER - TY - JOUR TI - Anisotropic Elastic Modulus of Oriented Regioregular Poly(3-hexylthiophene) Films AU - Awartani, Omar M. AU - Zhao, Bingxiao AU - Currie, Tyler AU - Kline, R. Joseph AU - Zikry, Mohammed A. AU - Brendan T. O'Connor, T2 - MACROMOLECULES AB - Specific morphological features of polymer semiconductors are often promoted in devices to optimize optoelectronic behavior. Less studied is the role of morphology on the mechanical properties of the film, such as elastic modulus, which is an important property for the development of flexible and stretchable devices. To gain insight into the morphological origin of elasticity in polymer semiconductors and its relationship to charge transport, we study the anisotropic in-plane elastic modulus of strain-aligned regioregular poly(3-hexylthiophene) (P3HT) films and compare the results to previously measured field effect charge mobility. The film morphology is varied through the amount of applied strain and post strain thermal annealing. Morphological characterization includes UV–vis optical spectroscopy and X-ray diffraction. The elastic modulus is measured using a buckling-based measurement technique. The elastic modulus of the film is found to decrease as the film is plastically strained. Thermally annealing the strained films results in a large in-plane elastic modulus anisotropy, where the modulus increases in the direction of backbone alignment and decreases in the transverse direction. The measured elastic modulus is compared to the film morphology, showing a dependence on both in-plane polymer chain alignment and local aggregate order. Comparing the elastic modulus to field effect mobility shows that they are not necessarily correlated, which has important implication for flexible organic electronic device design. DA - 2016/1/12/ PY - 2016/1/12/ DO - 10.1021/acs.macromol.5b02680 VL - 49 IS - 1 SP - 327-333 SN - 1520-5835 ER - TY - JOUR TI - X-ray polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR) AU - Krawczynski, H. S. AU - Stern, D. AU - Harrison, F. A. AU - Kislat, F. F. AU - Zajczyk, A. AU - Beilicke, M. AU - Hoormann, J. AU - Guo, Q. AU - Endsley, R. AU - Ingram, A. R. AU - Miyasaka, H. AU - Madsen, K. K. AU - Aaron, K. M. AU - Amini, R. AU - Baring, M. G. AU - Beheshtipour, B. AU - Bodaghee, A. T2 - Astroparticle Physics DA - 2016/// PY - 2016/// VL - 75 SP - 8-28 ER - TY - JOUR TI - Visualizing the Path of DNA through Proteins Using DREEM Imaging AU - Wu, Dong AU - Kaur, Parminder AU - Li, Zimeng M. AU - Bradford, Kira C. AU - Wang, Hong AU - Erie, Dorothy A. T2 - MOLECULAR CELL AB - Many cellular functions require the assembly of multiprotein-DNA complexes. A growing area of structural biology aims to characterize these dynamic structures by combining atomic-resolution crystal structures with lower-resolution data from techniques that provide distributions of species, such as small-angle X-ray scattering, electron microscopy, and atomic force microscopy (AFM). A significant limitation in these combinatorial methods is localization of the DNA within the multiprotein complex. Here, we combine AFM with an electrostatic force microscopy (EFM) method to develop an exquisitely sensitive dual-resonance-frequency-enhanced EFM (DREEM) capable of resolving DNA within protein-DNA complexes. Imaging of nucleosomes and DNA mismatch repair complexes demonstrates that DREEM can reveal both the path of the DNA wrapping around histones and the path of DNA as it passes through both single proteins and multiprotein complexes. Finally, DREEM imaging requires only minor modifications of many existing commercial AFMs, making the technique readily available. DA - 2016/1/21/ PY - 2016/1/21/ DO - 10.1016/j.molcel.2015.12.012 VL - 61 IS - 2 SP - 315-323 SN - 1097-4164 ER - TY - JOUR TI - Ultracold-neutron production and up-scattering in superfluid helium between 1.1 K and 2.4 K AU - Leung, K. K. H. AU - Ivanov, S. AU - Piegsa, F. M. AU - Simson, M. AU - Zimmer, O. T2 - Physical Review C AB - Ultracold neutrons (UCNs) were produced in superfluid helium using the PF1B cold-neutron beam facility at the Institut Laue-Langevin. A 4-liter beryllium-coated converter volume with a mechanical valve and windowless stainless-steel extraction system were used to accumulate and guide UCNs to a detector at room temperature. At a converter temperature of 1.08 K the total storage time constant in the vessel was $(20.3\ifmmode\pm\else\textpm\fi{}1.2)\phantom{\rule{0.28em}{0ex}}\mathrm{s}$ and the number of UCNs counted after accumulated was $91\phantom{\rule{0.16em}{0ex}}700\ifmmode\pm\else\textpm\fi{}300$. From this, we derive a volumetric UCN production rate of $(6.9\ifmmode\pm\else\textpm\fi{}1.7)\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, which includes a correction for losses in the converter during UCN extraction caused by the short storage time, but not accounting for UCN transport and detection efficiencies. The up-scattering rate of UCNs caused by excitations in the superfluid was studied by scanning the temperature between $1.2$ K and $2.4\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Using the temperature-dependent UCN production rate calculated from inelastic neutron scattering data, the only UCN up-scattering process found to occur was from two-phonon scattering. Our analysis for $T<1.95\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ rules out the contributions from roton-phonon scattering to $<29%$ (95% C.I.) and from one-phonon absorption to $<47%$ (95% C.I.) of their predicted levels. DA - 2016/2/4/ PY - 2016/2/4/ DO - 10.1103/physrevc.93.025501 VL - 93 IS - 2 SP - J2 - Phys. Rev. C LA - en OP - SN - 2469-9985 2469-9993 UR - http://dx.doi.org/10.1103/PhysRevC.93.025501 DB - Crossref ER - TY - JOUR TI - TRF2-Mediated Control of Telomere DNA Topology as a Mechanism for Chromosome-End Protection AU - Benarroch-Popivker, Delphine AU - Pisano, Sabrina AU - Mendez-Bermudez, Aaron AU - Lototska, Liudmyla AU - Kaur, Parminder AU - Bauwens, Serge AU - Djerbi, Nadir AU - Latrick, Chrysa M. AU - Fraisier, Vincent AU - Pei, Bei AU - Gay, Alexandre AU - Jaune, Emilie AU - Foucher, Kevin AU - Cherfils-Vicini, Julien AU - Aeby, Eric AU - Miron, Simona AU - Londoño-Vallejo, Arturo AU - Ye, Jing AU - Le Du, Marie-Hélène AU - Wang, Hong AU - Gilson, Eric AU - Giraud-Panis, Marie-Josèphe T2 - Molecular Cell AB - The shelterin proteins protect telomeres against activation of the DNA damage checkpoints and recombinational repair. We show here that a dimer of the shelterin subunit TRF2 wraps ∼ 90 bp of DNA through several lysine and arginine residues localized around its homodimerization domain. The expression of a wrapping-deficient TRF2 mutant, named Top-less, alters telomeric DNA topology, decreases the number of terminal loops (t-loops), and triggers the ATM checkpoint, while still protecting telomeres against non-homologous end joining (NHEJ). In Top-less cells, the protection against NHEJ is alleviated if the expression of the TRF2-interacting protein RAP1 is reduced. We conclude that a distinctive topological state of telomeric DNA, controlled by the TRF2-dependent DNA wrapping and linked to t-loop formation, inhibits both ATM activation and NHEJ. The presence of RAP1 at telomeres appears as a backup mechanism to prevent NHEJ when topology-mediated telomere protection is impaired. DA - 2016/1// PY - 2016/1// DO - 10.1016/J.MOLCEL.2015.12.009 VL - 61 IS - 2 SP - 274-286 J2 - Molecular Cell LA - en OP - SN - 1097-2765 UR - http://dx.doi.org/10.1016/J.MOLCEL.2015.12.009 DB - Crossref ER - TY - JOUR TI - Symmetric and standard matter neutrino resonances above merging compact objects AU - Malkus, A. AU - McLaughlin, G. C. AU - Surman, R. T2 - PHYSICAL REVIEW D AB - Matter-neutrino resonances (MNR) can occur in environments where the flux of electron antineutrinos is greater than the flux of electron neutrinos. These resonances may result in dramatic neutrino flavor transformation. Compact object merger disks are an example of an environment where electron antineutrinos outnumber neutrinos. We study MNR resonances in several such disk configurations and find two qualitatively different types of matter-neutrino resonances: a standard MNR and a symmetric MNR. We examine the transformation that occurs in each type of resonance and explore the consequences for nucleosynthesis. DA - 2016/2/17/ PY - 2016/2/17/ DO - 10.1103/physrevd.93.045021 VL - 93 IS - 4 SP - SN - 2470-0029 ER - TY - JOUR TI - Survival analysis approach to account for non-exponential decay rate effects in lifetime experiments AU - Coakley, K. J. AU - Dewey, M. S. AU - Huber, M. G. AU - Huffer, C. R. AU - Huffman, P. R. AU - Marley, D. E. AU - Mumm, H. P. AU - O'Shaughnessy, C. M. AU - Schelhammer, K. W. AU - Thompson, A. K. AU - Yue, A. T. T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - In a variety of neutron lifetime experiments, in addition to $\beta-$decay, neutrons can be lost by other mechanisms including wall losses. Failure to account for these other loss mechanisms produces systematic measurement error and associated systematic uncertainties in neutron lifetime measurements. In this work, we develop a physical model for neutron wall losses and construct a competing risks survival analysis model to account for losses due to the joint effect of $\beta-$decay losses, wall losses of marginally trapped neutrons, and an additional absorption mechanism. We determine the survival probability function associated with the wall loss mechanism by a Monte Carlo method. Based on a fit of the competing risks model to a subset of the NIST experimental data, we determine the mean lifetime of trapped neutrons to be approximately 700 s -- considerably less than the current best estimate of (880.1 $\pm$ 1.1) s promulgated by the Particle Data Group [1]. Currently, experimental studies are underway to determine if this discrepancy can be explained by neutron capture by ${}^3$He impurities in the trapping volume. Analysis of the full NIST data will be presented in a later publication. DA - 2016/3/21/ PY - 2016/3/21/ DO - 10.1016/j.nima.2015.12.064 VL - 813 SP - 84-95 SN - 1872-9576 UR - https://doi.org/10.1016/j.nima.2015.12.064 KW - Competing risks KW - Magnetic trapping KW - Marginally trapped neutrons KW - Neutron lifetime KW - Survival analysis KW - Symplectic integration ER - TY - JOUR TI - Superlinearly scalable noise robustness of redundant coupled dynamical systems AU - Kohar, Vivek AU - Kia, Behnam AU - Lindner, John F. AU - Ditto, William L. T2 - PHYSICAL REVIEW E AB - We illustrate through theory and numerical simulations that redundant coupled dynamical systems can be extremely robust against local noise in comparison to uncoupled dynamical systems evolving in the same noisy environment. Previous studies have shown that the noise robustness of redundant coupled dynamical systems is linearly scalable and deviations due to noise can be minimized by increasing the number of coupled units. Here, we demonstrate that the noise robustness can actually be scaled superlinearly if some conditions are met and very high noise robustness can be realized with very few coupled units. We discuss these conditions and show that this superlinear scalability depends on the nonlinearity of the individual dynamical units. The phenomenon is demonstrated in discrete as well as continuous dynamical systems. This superlinear scalability not only provides us an opportunity to exploit the nonlinearity of physical systems without being bogged down by noise but may also help us in understanding the functional role of coupled redundancy found in many biological systems. Moreover, engineers can exploit superlinear noise suppression by starting a coupled system near (not necessarily at) the appropriate initial condition. DA - 2016/3/11/ PY - 2016/3/11/ DO - 10.1103/physreve.93.032213 VL - 93 IS - 3 SP - SN - 1550-2376 ER - TY - JOUR TI - Solid capillarity: when and how does surface tension deform soft solids? AU - Andreotti, Bruno AU - Baeumchen, Oliver AU - Boulogne, Francois AU - Daniels, Karen E. AU - Dufresne, Eric R. AU - Perrin, Hugo AU - Salez, Thomas AU - Snoeijer, Jacco H. AU - Style, Robert W. T2 - SOFT MATTER AB - Soft solids differ from stiff solids in an important way: their surface stresses can drive large deformations. Based on a topical workshop held in the Lorentz Center in Leiden, this Opinion highlights some recent advances in the growing field of solid capillarity and poses key questions for its advancement. DA - 2016/// PY - 2016/// DO - 10.1039/c5sm03140k VL - 12 IS - 12 SP - 2993-2996 SN - 1744-6848 ER - TY - JOUR TI - Rigidifying Nonplanar Perylene Diimides by Ring Fusion Toward Geometry-Tunable Acceptors for High-Performance Fullerene-Free Solar Cells AU - Zhong, Hongliang AU - Wu, Chen-Hao AU - Li, Chang-Zhi AU - Carpenter, Joshua AU - Chueh, Chu-Chen AU - Chen, Jung-Yao AU - Ade, Harald AU - Jen, Alex K. -Y. T2 - ADVANCED MATERIALS AB - Rigid fused perylene diimide (PDI) dimers bridged with heterocycles exhibit superior photovoltaic performance compared to their unfused semiflexible analogues. Changing the chalcogen atoms in the aromatic bridges gradually increases the twist angles between the two PDI planes, leading to a varied morphology in which the one bridged by thiophene achieves a balance and shows the best efficiency of 6.72%. DA - 2016/2/3/ PY - 2016/2/3/ DO - 10.1002/adma.201504120 VL - 28 IS - 5 SP - 951-958 SN - 1521-4095 KW - fused rings KW - nonfullerene acceptors KW - organic photovoltaics KW - perylene diimides KW - power conversion efficiency ER - TY - JOUR TI - Particle spectra and efficiency in nonlinear relativistic shock acceleration - survey of scattering models AU - Ellison, Donald C. AU - Warren, Donald C. AU - Bykov, Andrei M. T2 - MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY AB - We include a general form for the scattering mean free path in a nonlinear Monte Carlo model of relativistic shock formation and Fermi acceleration. Particle-in-cell (PIC) simulations, as well as analytic work, suggest that relativistic shocks tend to produce short-scale, self-generated magnetic turbulence that leads to a scattering mean free path (mfp) with a stronger momentum dependence than the mfp ~ p dependence for Bohm diffusion. In unmagnetized shocks, this turbulence is strong enough to dominate the background magnetic field so the shock can be treated as parallel regardless of the initial magnetic field orientation, making application to gamma-ray bursts (GRBs), pulsar winds, Type Ibc supernovae, and extra-galactic radio sources more straightforward and realistic. In addition to changing the scale of the shock precursor, we show that, when nonlinear effects from efficient Fermi acceleration are taken into account, the momentum dependence of the mfp has an important influence on the efficiency of cosmic-ray production as well as the accelerated particle spectral shape. These effects are absent in nonrelativistic shocks and do not appear in relativistic shock models unless nonlinear effects are self-consistently described. We show, for limited examples, how the changes in Fermi acceleration translate to changes in the intensity and spectral shape of gamma-ray emission from proton-proton interactions and pion-decay radiation. DA - 2016/3/1/ PY - 2016/3/1/ DO - 10.1093/mnras/stv2912 VL - 456 IS - 3 SP - 3090-3099 SN - 1365-2966 KW - acceleration of particles KW - MHD KW - shock waves KW - turbulence KW - cosmic rays ER - TY - JOUR TI - Origins of polarization-dependent anisotropic X-ray scattering from organic thin films AU - Gann, Eliot AU - Collins, Brian A. AU - Tang, Maolong AU - Tumbleston, John R. AU - Mukherjee, Subrangsu AU - Ade, Harald T2 - JOURNAL OF SYNCHROTRON RADIATION AB - Organic thin films that have no overall in-plane directional ordering often nonetheless produce anisotropic scattering patterns that rotate with the polarization of incident resonant X-rays. Isotropic symmetry is broken by local correlations between molecular orientation and domain structure. Such examples of molecular alignment at domain interfaces and within the bulk of domains, which are both critical to fields such as organic electronics, are simulated and compared with experimental scattering. Anisotropic scattering patterns are found to allow unambiguous identification of the mechanism of local molecular orientation correlations and, as such, promise to be both distinct and complementary to isotropic scattering intensity as a general measure of thin film microstructure. DA - 2016/1// PY - 2016/1// DO - 10.1107/s1600577515019074 VL - 23 SP - 219-227 SN - 1600-5775 KW - polarization KW - scattering KW - RSoXS KW - PSoXS KW - resonant scattering KW - simulation ER - TY - JOUR TI - Neutron limit on the strongly-coupled chameleon field AU - Li, K. AU - Arif, M. AU - Cory, D. G. AU - Haun, R. AU - Heacock, B. AU - Huber, M. G. AU - Nsofini, J. AU - Pushin, D. A. AU - Saggu, P. AU - Sarenac, D. AU - Shahi, C. B. AU - Skavysh, V. AU - Snow, W. M. AU - Young, A. R. T2 - Physical Review D AB - The physical origin of the dark energy that causes the accelerated expansion rate of the Universe is one of the major open questions of cosmology. One set of theories postulates the existence of a self-interacting scalar field for dark energy coupling to matter. In the chameleon dark energy theory, this coupling induces a screening mechanism such that the field amplitude is nonzero in empty space but is greatly suppressed in regions of terrestrial matter density. However measurements performed under appropriate vacuum conditions can enable the chameleon field to appear in the apparatus, where it can be subjected to laboratory experiments. Here we report the most stringent upper bound on the free neutron-chameleon coupling in the strongly coupled limit of the chameleon theory using neutron interferometric techniques. Our experiment sought the chameleon field through the relative phase shift it would induce along one of the neutron paths inside a perfect crystal neutron interferometer. The amplitude of the chameleon field was actively modulated by varying the millibar pressures inside a dual-chamber aluminum cell. We report a 95% confidence level upper bound on the neutron-chameleon coupling β ranging from β < 4.7 × 106 for a Ratra-Peebles index of n = 1 in the nonlinear scalar field potential to β < 2.4 × 107 for n = 6, one order of magnitude more sensitive than the most recent free neutron limit for intermediate n. Similar experiments can explore the full parameter range for chameleon dark energy in the foreseeable future. DA - 2016/3/11/ PY - 2016/3/11/ DO - 10.1103/physrevd.93.062001 VL - 93 IS - 6 SP - J2 - Phys. Rev. D LA - en OP - SN - 2470-0010 2470-0029 UR - http://dx.doi.org/10.1103/PhysRevD.93.062001 DB - Crossref ER - TY - JOUR TI - Low mass binary neutron star mergers: Gravitational waves and neutrino emission AU - Foucart, F. AU - Haas, R. AU - Duez, M. D. AU - O'Connor, E. AU - Ott, C. D. AU - Roberts, L. AU - Kidder, L. E. AU - Lippuner, J. AU - Pfeiffer, H. P. AU - Scheel, M. A. T2 - Physical Review D DA - 2016/// PY - 2016/// VL - 93 IS - 4 ER - TY - JOUR TI - Highly Efficient Organic Solar Cells with Improved Vertical Donor-Acceptor Compositional Gradient Via an Inverted Off-Center Spinning Method AU - Huang, Jiang AU - Carpenter, Joshua H. AU - Li, Chang-Zhi AU - Yu, Jun-Sheng AU - Ade, Harald AU - Jen, Alex K. -Y. T2 - ADVANCED MATERIALS AB - A novel, yet simple solution fabrication technique to address the trade-off between photocurrent and fill factor in thick bulk heterojunction organic solar cells is described. The inverted off-center spinning technique promotes a vertical gradient of the donor–acceptor phase-separated morphology, enabling devices with near 100% internal quantum efficiency and a high power conversion efficiency of 10.95%. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. DA - 2016/2/3/ PY - 2016/2/3/ DO - 10.1002/adma.201504014 VL - 28 IS - 5 SP - 967-974 SN - 1521-4095 KW - bulk heterojunctions KW - off-center spin KW - organic solar cells KW - power conversion efficiency ER - TY - JOUR TI - Growth of thermally stable crystalline C60 films on flat-lying copper phthalocyanine AU - McAfee, Terry AU - Apperson, Aubrey AU - Ade, Harald AU - Dougherty, Daniel B. T2 - Journal of Materials Chemistry A AB - We observe thermally stable growth of fcc(111) films of fullerene-C60 on top of crystalline, flat-lying, CuPc film structures on graphite using combined grazing incidence wide-angle X-ray scattering and atomic force microscopy. DA - 2016/// PY - 2016/// DO - 10.1039/C5TA06820G VL - 4 IS - 3 SP - 1028-1032 J2 - J. Mater. Chem. A LA - en OP - SN - 2050-7488 2050-7496 UR - http://dx.doi.org/10.1039/C5TA06820G DB - Crossref ER - TY - JOUR TI - G11.2-0.3: THE YOUNG REMNANT OF A STRIPPED-ENVELOPE SUPERNOVA AU - Borkowski, Kazimierz J. AU - Reynolds, Stephen P. AU - Roberts, Mallory S. E. T2 - ASTROPHYSICAL JOURNAL AB - We present results of a 400-ks Chandra observation of the young shell supernova remnant (SNR) G11.2-0.3, containing a pulsar and pulsar-wind nebula (PWN). We measure a mean expansion rate for the shell since 2000 of 0.0277+/-0.0018% per yr, implying an age between 1400 and 2400 yr, and making G11.2-0.3 one of the youngest core-collapse SNRs in the Galaxy. However, we find very high absorption ($A_V \sim 16^m \pm 2^m$), confirming near-IR determinations and ruling out a claimed association with the possible historical SN of 386 CE. The PWN shows strong jets and a faint torus within a larger, more diffuse region of radio emission and nonthermal X-rays. Central soft thermal X-ray emission is anticorrelated with the PWN; that, and more detailed morphological evidence, indicates that the reverse shock has already reheated all ejecta and compressed the PWN. The pulsar characteristic energy-loss timescale is well in excess of the remnant age, and we suggest that the bright jets have been produced since the recompression. The relatively pronounced shell and diffuse hard X-ray emission in the interior, enhanced at the inner edge of the shell, indicate that the immediate circumstellar medium into which G11.2-0.3 is expanding was quite anisotropic. We propose a possible origin for G11.2-0.3 in a stripped-envelope progenitor that had lost almost all its envelope mass, in an anisotropic wind or due to binary interaction, leaving a compact core whose fast winds swept previously lost mass into a dense irregular shell, and which exploded as a Type cIIb or Ibc supernova. DA - 2016/3/10/ PY - 2016/3/10/ DO - 10.3847/0004-637x/819/2/160 VL - 819 IS - 2 SP - SN - 1538-4357 KW - ISM: individual objects (G11.20.3) KW - ISM: supernova remnants KW - X-rays: ISM ER - TY - JOUR TI - Enhanced electrostatic force microscopy reveals higher-order DNA looping mediated by the telomeric protein TRF2 AU - Kaur, Parminder AU - Wu, Dong AU - Lin, Jiangguo AU - Countryman, Preston AU - Bradford, Kira C. AU - Erie, Dorothy A. AU - Riehn, Robert AU - Opresko, Patricia L. AU - Wang, Hong T2 - Scientific Reports AB - Shelterin protein TRF2 modulates telomere structures by promoting dsDNA compaction and T-loop formation. Advancement of our understanding of the mechanism underlying TRF2-mediated DNA compaction requires additional information regarding DNA paths in TRF2-DNA complexes. To uncover the location of DNA inside protein-DNA complexes, we recently developed the Dual-Resonance-frequency-Enhanced Electrostatic force Microscopy (DREEM) imaging technique. DREEM imaging shows that in contrast to chromatin with DNA wrapping around histones, large TRF2-DNA complexes (with volumes larger than TRF2 tetramers) compact DNA inside TRF2 with portions of folded DNA appearing at the edge of these complexes. Supporting coarse-grained molecular dynamics simulations uncover the structural requirement and sequential steps during TRF2-mediated DNA compaction and result in folded DNA structures with protruding DNA loops as seen in DREEM imaging. Revealing DNA paths in TRF2 complexes provides new mechanistic insights into structure-function relationships underlying telomere maintenance pathways. DA - 2016/2/9/ PY - 2016/2/9/ DO - 10.1038/SREP20513 VL - 6 IS - 1 J2 - Sci Rep LA - en OP - SN - 2045-2322 UR - http://dx.doi.org/10.1038/SREP20513 DB - Crossref ER - TY - JOUR TI - Enabling and challenging factors in institutional reform: The case of SCALE-UP AU - Foote, Kathleen AU - Knaub, Alexis AU - Henderson, Charles AU - Dancy, Melissa AU - Beichner, Robert J. T2 - Physical Review Physics Education Research AB - While many innovative teaching strategies exist, integration into undergraduate science teaching has been frustratingly slow. This study aims to understand the low uptake of research-based instructional innovations by studying 21 successful implementations of the Student Centered Active Learning with Upside-down Pedagogies (SCALE-UP) instructional reform. SCALE-UP significantly restructures the classroom environment and pedagogy to promote highly active and interactive instruction. Although originally designed for university introductory physics courses, SCALE-UP has spread to many other disciplines at hundreds of departments around the world. This study reports findings from in-depth, open-ended interviews with 21 key contact people involved with successful secondary implementations of SCALE-UP throughout the United States. We defined successful implementations as those who restructured their pedagogy and classroom and sustained and/or spread the change. Interviews were coded to identify the most common enabling and challenging factors during reform implementation and compared to the theoretical framework of Kotter’s 8-step Change Model. The most common enabling influences that emerged are documenting and leveraging evidence of local success, administrative support, interaction with outside SCALE-UP user(s), and funding. Many challenges are linked to the lack of these enabling factors including difficulty finding funding, space, and administrative and/or faculty support for reform. Our focus on successful secondary implementations meant that most interviewees were able to overcome challenges. Presentation of results is illuminated with case studies, quotes, and examples that can help secondary implementers with SCALE-UP reform efforts specifically. We also discuss the implications for policy makers, researchers, and the higher education community concerned with initiating structural change.Received 22 June 2015DOI:https://doi.org/10.1103/PhysRevPhysEducRes.12.010103This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasInstructional strategiesResearch methodologyPhysics Education Research DA - 2016/2/4/ PY - 2016/2/4/ DO - 10.1103/physrevphyseducres.12.010103 VL - 12 IS - 1 SP - J2 - Phys. Rev. Phys. Educ. Res. LA - en OP - SN - 2469-9896 UR - http://dx.doi.org/10.1103/PhysRevPhysEducRes.12.010103 DB - Crossref ER - TY - JOUR TI - Effect of Constrained Annealing on the Mechanical Properties of Electrospun Poly(ethylene oxide) Webs Containing Multiwalled Carbon Nanotubes AU - Bao, Jiaxing AU - Clarke, Laura I. AU - Gorga, Russell E. T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - ABSTRACT In this work, flexible nanofibrous membranes (mats) of poly(ethylene oxide) (PEO) with and without multiwall carbon nanotubes (MWNTs) were fabricated by electrospinning. The effects of annealing and MWNT concentration on mat morphology, MWNT dispersion within the nanofibers, and the mechanical properties of electrospun mats were studied. Annealing temperatures ranged from 60 °C to 64 °C [near the melting temperature (64 °C via differential scanning calorimetry)] for 4 minutes. Samples were annealed with and without applied tension (constrained and unconstrained annealing). Annealing at the highest temperature (64 °C), before the loss of fibrous morphology, significantly improved fiber–fiber bonding and therefore the tensile strength of the mats. Compared with unconstrained annealing, constrained annealing introduced fiber alignment (and therefore molecular orientation) along the tensile axis (direction of constraint) during annealing and resulted in a significant increase in modulus for all samples (with and without MWNTs). The use of constrained annealing may be a facile approach to enhance modulus in nanofibrous mats while maintaining high porosity. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54 , 787–796 DA - 2016/4/15/ PY - 2016/4/15/ DO - 10.1002/polb.23960 VL - 54 IS - 8 SP - 787-796 SN - 1099-0488 KW - annealing KW - carbon nanotubes KW - crystallinity KW - mechanical properties KW - nanofibers ER - TY - JOUR TI - Complexified Path Integrals, Exact Saddles, and Supersymmetry AU - Behtash, Alireza AU - Dunne, Gerald V. AU - Schaefer, Thomas AU - Sulejmanpasic, Tin AU - Uensal, Mithat T2 - PHYSICAL REVIEW LETTERS AB - In the context of two illustrative examples from supersymmetric quantum mechanics we show that the semiclassical analysis of the path integral requires complexification of the configuration space and action, and the inclusion of complex saddle points, even when the parameters in the action are real. We find new exact complex saddles, and show that without their contribution the semiclassical expansion is in conflict with basic properties such as the positive semidefiniteness of the spectrum, as well as constraints of supersymmetry. Generic saddles are not only complex, but also possibly multivalued and even singular. This is in contrast to instanton solutions, which are real, smooth, and single valued. The multivaluedness of the action can be interpreted as a hidden topological angle, quantized in units of π in supersymmetric theories. The general ideas also apply to nonsupersymmetric theories. DA - 2016/1/6/ PY - 2016/1/6/ DO - 10.1103/physrevlett.116.011601 VL - 116 IS - 1 SP - SN - 1079-7114 UR - http://inspirehep.net/record/1396147 ER - TY - JOUR TI - A Difluorobenzoxadiazole Building Block for Efficient Polymer Solar Cells AU - Zhao, Jingbo AU - Li, Yunke AU - Hunt, Adrian AU - Zhang, Jianquan AU - Yao, Huatong AU - Li, Zhengke AU - Zhang, Jie AU - Huang, Fei AU - Ade, Harald AU - Yan, He T2 - ADVANCED MATERIALS AB - A difluorobenzoxadiazole building block is synthesized and utilized to construct a conjugated polymer leading to high-performance thick-film polymer solar cells with a V(OC) of 0.88 V and a power conversion efficiency of 9.4%. This new building block can be used in many possible polymer structures for various organic electro-nic applications. DA - 2016/3/2/ PY - 2016/3/2/ DO - 10.1002/adma.201504611 VL - 28 IS - 9 SP - 1868-1873 SN - 1521-4095 ER - TY - JOUR TI - A COMPACT X-RAY SOURCE IN THE RADIO PULSAR-WIND NEBULA G141.2+5.0 AU - Reynolds, Stephen P. AU - Borkowski, Kazimierz J. T2 - ASTROPHYSICAL JOURNAL LETTERS AB - We report the results of a 50 ks Chandra observation of the recently discovered radio object G141.2+5.0, presumed to be a pulsar-wind nebula. We find a moderately bright unresolved X-ray source that we designate CXOU J033712.8 615302 coincident with the central peak radio emission. An absorbed power-law fit to the 241 counts describes the data well, with absorbing column cm−2 and photon index . For a distance of 4 kpc, the unabsorbed luminosity between 0.5 and 8 keV is erg s−1 (90% confidence intervals). Both LX and Γ are quite typical of pulsars in PWNe. No extended emission is seen; we estimate a conservative upper limit to the surface brightness of any X-ray PWN near the point source to be erg cm−2 s−1 arcsec−2 between 0.5 and 8 keV, assuming the same spectrum as the point source; for a nebula of diameter , the flux limit is 6% of the flux of the point source. The steep radio spectrum of the PWN (), if continued to the X-ray without a break, predicts erg s−1, so additional spectral steepening between radio and X-rays is required, as is true of all known PWNe. The high Galactic latitude gives a z-distance of 350 pc above the Galactic plane, quite unusual for a Population I object. DA - 2016/1/10/ PY - 2016/1/10/ DO - 10.3847/2041-8205/816/2/l27 VL - 816 IS - 2 SP - SN - 2041-8213 UR - https://doi.org/10.3847/2041-8205/816/2/L27 KW - ISM: individual objects (G141.2+5.0) KW - ISM: jets and outflows KW - pulsars: general ER - TY - JOUR TI - Optical investigation of gold shell enhanced 25 nm diameter upconverted fluorescence emission AU - Green, Kory AU - Wirth, Janina AU - Lim, Shuang Fang T2 - Nanotechnology AB - We enhance the efficiency of upconverting nanoparticles by investigating the plasmonic coupling of 25 nm diameter NaYF4:Yb, Er nanoparticles with a gold-shell coating, and study the physical mechanism of enhancement by single-particle, time-resolved spectroscopy. A three-fold overall increase in emission intensity, and five-fold increase of green emission for these plasmonically enhanced particles have been achieved. Using a combination of structural and fluorescent imaging, we demonstrate that fluorescence enhancement is based on the photonic properties of single, isolated particles. Time-resolved spectroscopy shows that the increase in fluorescence is coincident with decreased rise time, which we attribute to an enhanced absorption of infrared light and energy transfer from Yb(3+) to Er(3+) atoms. Time-resolved spectroscopy also shows that fluorescence life-times are decreased to different extents for red and green emission. This indicates that the rate of photon emission is not suppressed, as would be expected for a metallic cavity, but rather enhanced because the metal shell acts as an optical antenna, with differing efficiency at different wavelengths. DA - 2016/2/19/ PY - 2016/2/19/ DO - 10.1088/0957-4484/27/13/135201 VL - 27 IS - 13 SP - 135201 J2 - Nanotechnology OP - SN - 0957-4484 1361-6528 UR - http://dx.doi.org/10.1088/0957-4484/27/13/135201 DB - Crossref KW - plasmonic KW - upconversion KW - gold shell KW - fluorescence KW - time-resolved KW - AFM KW - structure and optical correlation ER - TY - JOUR TI - Optical Control of Magnetic Feshbach Resonances by Closed-Channel Electromagnetically Induced Transparency AU - Jagannathan, A. AU - Arunkumar, N. AU - Joseph, J. A. AU - Thomas, J. E. T2 - PHYSICAL REVIEW LETTERS AB - Using an optically-trapped mixture of the two lowest hyperfine states of a $^6$Li Fermi gas, we observe two-field optical tuning of the narrow Feshbach resonance by up to 3 G and an increase in spontaneous lifetime near the broad resonance from $0.5$ ms to $0.4$ s. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, that agrees in shape and magnitude with measurements for both broad and narrow resonances. DA - 2016/2/17/ PY - 2016/2/17/ DO - 10.1103/physrevlett.116.075301 VL - 116 IS - 7 SP - SN - 1079-7114 ER - TY - JOUR TI - Modulating the permeability of ferritin channels AU - Bernacchioni, C. AU - Ghini, V. AU - Theil, E. C. AU - Turano, P. T2 - RSC ADVANCES AB - Electric field gradients across the C3 and C4 ferritin channels controls the directional Fe2+fluxes towards the catalytic ferroxidase center. DA - 2016/// PY - 2016/// DO - 10.1039/c5ra25056k VL - 6 IS - 25 SP - 21219-21227 SN - 2046-2069 ER - TY - JOUR TI - Model-Independent Determination of the Shear Viscosity of a Trapped Unitary Fermi gas: Application to High-Temperature Data AU - Bluhm, M. AU - Schaefer, T. T2 - PHYSICAL REVIEW LETTERS AB - Determinations of the shear viscosity of trapped ultracold gases suffer from systematic, uncontrolled uncertainties related to the treatment of the dilute part of the gas cloud. In this work we present an analysis of expansion experiments based on a new method, anisotropic fluid dynamics, that interpolates between Navier-Stokes fluid dynamics at the center of the cloud and ballistic behavior in the dilute corona. We validate the method using a comparison between anisotropic fluid dynamics and numerical solutions of the Boltzmann equation. We then apply anisotropic fluid dynamics to the expansion data reported by Cao et al. In the high-temperature limit we find η=0.282(mT)^{3/2}, which agrees within about 5% with the theoretical prediction η=0.269(mT)^{3/2}. DA - 2016/3/18/ PY - 2016/3/18/ DO - 10.1103/physrevlett.116.115301 VL - 116 IS - 11 SP - SN - 1079-7114 UR - http://inspirehep.net/record/1407992 ER - TY - JOUR TI - Mechanisms of NH3 and NO2 detection in carbon-nanotube-based sensors: An ab initio investigation AU - Li, Yan AU - Hodak, Miroslav AU - Lu, Wenchang AU - Bernholc, J. T2 - Carbon AB - The mechanisms of NH3 and NO2 detection by single-walled carbon nanotube-based devices are investigated by ab initio calculations and the non-equilibrium Greens function (NEGF) methodology. While both NH3 and NO2 can physisorb to a pristine carbon nanotube, we show that their adsorption only results in small current changes through the device. For a carbon nanotube (CNT) attached to gold nanowire leads, the most sensitive detection site is at the CNT near the CNT-Au contact, where chemisorption occurs. The resulting change in electron transmission and low-bias current can lead to over 30% sensitivity. While both NH3 and NO2 can also chemisorb at the Au electrodes, their adsorption results in only a small change in the plurality of the conducting levels of the gold layers, and thus a small effect on current. In order to enhance the detection sensitivity, it is thus beneficial to mask the electrodes to prevent chemisorption. Furthermore, the length of the pure CNT segment does not strongly affect the relative sensitivity. Our results suggest that a short-CNT device with exposed contact regions and masked electrodes would have the greatest sensitivity. DA - 2016/5// PY - 2016/5// DO - 10.1016/j.carbon.2016.01.092 VL - 101 SP - 177-183 J2 - Carbon LA - en OP - SN - 0008-6223 UR - http://dx.doi.org/10.1016/j.carbon.2016.01.092 DB - Crossref ER - TY - JOUR TI - Magnetoelectric oxide films for spin manipulation in graphene AU - Stuart, S. C. AU - Gray, B. AU - Nevola, D. AU - Su, L. AU - Sachet, E. AU - Ulrich, M. AU - Dougherty, D. B. T2 - PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS AB - The challenge of creating a graphene spin field effect transistor (spin-FET) demands a magnetic gate dielectric material whose magnetization can be switched electrically. We have grown films of Cr2O3 on top of graphite and graphene by pulsed laser deposition that shows this crucial functionality. We demonstrate that the Cr2O3 films are magnetoelectric by poling them in combined electric and magnetic fields and then using magnetic force microscopy to observe spontaneous surface domain structure as a function of poling field. In addition, we show that the electric field created by a conducting AFM tip can be used to write magnetic patterns in the film that demonstrate the kind of continuous magnetoelectric control needed for a prototype spin-FET. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) DA - 2016/3// PY - 2016/3// DO - 10.1002/pssr.201510433 VL - 10 IS - 3 SP - 242-247 SN - 1862-6270 KW - magnetoelectrics KW - spintronics KW - Cr2O3 KW - films KW - graphene KW - spin field effect transistors KW - scanned probe microscopy ER - TY - JOUR TI - Influence of fluorination on the properties and performance of isoindigo-quaterthiophene-based polymers AU - Hu, Huawei AU - Jiang, Kui AU - Kim, Joo-Hyun AU - Yang, Guofang AU - Li, Zhengke AU - Ma, Tingxuan AU - Lu, Guanghao AU - Qu, Yongquan AU - Ade, Harald AU - Yan, He T2 - JOURNAL OF MATERIALS CHEMISTRY A AB - Isoindigo–quaterthiophene-based polymers are synthesized and compared to investigate the relationship between the fluorination position and photovoltaic properties. DA - 2016/// PY - 2016/// DO - 10.1039/c6ta00006a VL - 4 IS - 14 SP - 5039-5043 SN - 2050-7496 ER - TY - JOUR TI - CuNb1-xTaxO3 (x <= 0.25) solid solutions: impact of Ta(V) substitution and Cu(I) deficiency on their structure, photocatalytic, and photoelectrochemical properties AU - Zoellner, Brandon AU - Stuart, Sean AU - Chung, Ching-Chang AU - Dougherty, Daniel B. AU - Jones, Jacob L. AU - Maggard, Paul A. T2 - JOURNAL OF MATERIALS CHEMISTRY A AB - Investigation of CuNb1−xTaxO3has led to new insights into the visible-light photocurrents and photocatalytic activities of solid solutions. DA - 2016/// PY - 2016/// DO - 10.1039/c5ta06609c VL - 4 IS - 8 SP - 3115-3126 SN - 2050-7496 ER - TY - JOUR TI - Theory of light-enhanced phonon-mediated superconductivity AU - Sentef, M. A. AU - Kemper, A. F. AU - Georges, A. AU - Kollath, C. T2 - PHYSICAL REVIEW B AB - We investigate the dynamics of a phonon-mediated superconductor driven out of equilibrium. The electronic hopping amplitude is ramped down in time, resulting in an increased electronic density of states. The dynamics of the coupled electron-phonon model is investigated by solving Migdal-Eliashberg equations for the double-time Keldysh Green's functions. The increase of the density of states near the Fermi level leads to an enhancement of superconductivity when the system thermalizes to the new state at the same temperature. We provide a time- and momentum-resolved view on this thermalization process, and show that it involves fast processes associated with single-particle scattering and much slower dynamics associated with the superconducting order parameter. The importance of electron-phonon coupling for the rapid enhancement and the efficient thermalization of superconductivity is demonstrated, and the results are compared to a BCS time-dependent mean-field approximation. DA - 2016/4/8/ PY - 2016/4/8/ DO - 10.1103/physrevb.93.144506 VL - 93 IS - 14 SP - SN - 2469-9969 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000373568900004&KeyUID=WOS:000373568900004 ER - TY - JOUR TI - Spin-orbit interactions in electronic structure quantum Monte Carlo methods AU - Melton, Cody A. AU - Zhu, Minyi AU - Guo, Shi AU - Ambrosetti, Alberto AU - Pederiva, Francesco AU - Mitas, Lubos T2 - PHYSICAL REVIEW A AB - We develop generalization of the fixed-phase diffusion Monte Carlo method for Hamiltonians which explicitly depends on particle spins such as for spin-orbit interactions. The method is formulated in a zero-variance manner and is similar to the treatment of nonlocal operators in commonly used static-spin calculations. Tests on atomic and molecular systems show that it is very accurate, on par with the fixed-node method. This opens electronic structure quantum Monte Carlo methods to a vast research area of quantum phenomena in which spin-related interactions play an important role. DA - 2016/4/7/ PY - 2016/4/7/ DO - 10.1103/physreva.93.042502 VL - 93 IS - 4 SP - SN - 2469-9934 ER - TY - JOUR TI - Pion structure function from leading neutron electroproduction and SU(2) flavor asymmetry AU - McKenney, J. R. AU - Sato, Nobuo AU - Melnitchouk, W. AU - Ji, Chueng-Ryong T2 - PHYSICAL REVIEW D AB - We examine the efficacy of pion exchange models to simultaneously describe leading neutron electroproduction at HERA and the $\bar{d}-\bar{u}$ flavor asymmetry in the proton. A detailed $\chi^2$ analysis of the ZEUS and H1 cross sections, when combined with constraints on the pion flux from Drell-Yan data, allows regions of applicability of one-pion exchange to be delineated. The analysis disfavors several models of the pion flux used in the literature, and yields an improved extraction of the pion structure function and its uncertainties at parton momentum fractions in the pion of $4 \times 10^{-4} \lesssim x_\pi \lesssim 0.05$ at a scale of $Q^2$=10 GeV$^2$. Based on the fit results, we provide estimates for leading proton structure functions in upcoming tagged deep-inelastic scattering experiments at Jefferson Lab on the deuteron with forward protons. DA - 2016/3/7/ PY - 2016/3/7/ DO - 10.1103/physrevd.93.054011 VL - 93 IS - 5 SP - SN - 2470-0029 ER - TY - JOUR TI - Elastic theory of origami-based metamaterials AU - Brunck, V. AU - Lechenault, F. AU - Reid, A. AU - Adda-Bedia, M. T2 - PHYSICAL REVIEW E AB - Origami offers the possibility for new metamaterials whose overall mechanical properties can be programed by acting locally on each crease. Starting from a thin plate and having knowledge about the properties of the material and the folding procedure, one would like to determine the shape taken by the structure at rest and its mechanical response. In this article, we introduce a vector deformation field acting on the imprinted network of creases that allows us to express the geometrical constraints of rigid origami structures in a simple and systematic way. This formalism is then used to write a general covariant expression of the elastic energy of n-creases meeting at a single vertex. Computations of the equilibrium states are then carried out explicitly in two special cases: the generalized waterbomb base and the Miura-Ori. For the waterbomb, we show a generic bistability for any number of creases. For the Miura folding, however, we uncover a phase transition from monostable to bistable states that explains the efficient deployability of this structure for a given range of geometrical and mechanical parameters. Moreover, the analysis shows that geometric frustration induces residual stresses in origami structures that should be taken into account in determining their mechanical response. This formalism can be extended to a general crease network, ordered or otherwise, and so opens new perspectives for the mechanics and the physics of origami-based metamaterials. DA - 2016/3/22/ PY - 2016/3/22/ DO - 10.1103/physreve.93.033005 VL - 93 IS - 3 SP - SN - 2470-0053 ER -