TY - RPRT TI - Solid oxide fuel cell process and apparatus AU - Cooper, M. AU - Bayless, D. AU - Trembly, J. DA - 2011/11/15/ PY - 2011/11/15/ M1 - 8,057,951 M3 - U.S. Patent SN - 8,057,951 ER - TY - JOUR TI - Atomic Layer Deposited Oxides for Passivation of Silicon Photoanodes for Solar Photoelectrochemical Cells AU - Kalanyan, B. AU - Parsons, G. N. AU - Elam, JW AU - Londergan, A AU - VanDerStraten, O AU - Roozeboom, F AU - DeGendt, S AU - Bent, SF AU - Delabie, A T2 - Atomic Layer Deposition Applications 7 AB - Although crystalline silicon is an industrially significant device substrate, its use in photoelectrochemical cells is complicated by the thin oxide film that forms at the electrode surface. We applied thin coatings of atomic layer deposited films on n- and p-type Si substrates to block the growth of SiO2 during solar light-driven water splitting reactions. Voltammetry accompanied by ellipsometric measurements show us that metal oxide coatings as thin as 1.6 nm are effective at stopping electrode oxidation during dark and photoelectrochemistry. We observed similar passivating behavior among TiO2, ZnO, and Al2O3 thin films. Titania and zinc oxide films enhanced photocurrent due to their absorption in the UV wavelengths. We also applied a common water oxidation catalyst, cobalt, to show the feasibility of catalyst integration on top of ALD passivating films. DA - 2011/// PY - 2011/// DO - 10.1149/1.3633679 VL - 41 IS - 2 SP - 285-292 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000305937200031&KeyUID=WOS:000305937200031 ER - TY - RPRT TI - Oxygen Carrying Materials AU - Fan, L.-S. AU - Sridhar, Deepak AU - Li, Fanxing DA - 2011/// PY - 2011/// M1 - US10502414B2, CN103635673B, AU2012253332B2, CA2835421A1, EP3584426A1 M3 - Patent SN - US10502414B2, CN103635673B, AU2012253332B2, CA2835421A1, EP3584426A1 ER - TY - RPRT TI - Systems for Converting Fuel AU - Fan, L.-S. AU - Kim, Hyung R. AU - Li, Fanxing AU - Zeng, Liang AU - Wang, Dawei AU - Wang, Fei DA - 2011/// PY - 2011/// M1 - US9903584B2 M3 - Patent SN - US9903584B2 ER - TY - CONF TI - 1-D dynamic modeling for moving bed reducer in chemical looping process AU - Zhou, Q. AU - Zeng, L. AU - Yang, H. AU - Yu, Z. AU - Wang, D. AU - Li, F. AU - Fan, L.-S. C2 - 2011/// C3 - 28th Annual International Pittsburgh Coal Conference 2011, PCC 2011 DA - 2011/// VL - 2 SP - 1210-1222 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84877616011&partnerID=MN8TOARS ER - TY - CONF TI - Process integration and analysis of chemical looping based power and fuel generation systems AU - Zeng, L. AU - Li, F. AU - Sridhar, D. AU - Kim, H.R. AU - Tong, A. AU - Luo, S. AU - Fan, L.-S. C2 - 2011/// C3 - 11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings DA - 2011/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84863127295&partnerID=MN8TOARS ER - TY - CONF TI - Iron-based chemical looping process for coal conversion AU - Kim, R. AU - Li, F. AU - Wang, D. AU - Sridhar, D. AU - Zeng, L. AU - Tong, A.S. AU - Wang, F. AU - Sun, Z. AU - Luo, S. AU - Fan, L.-S. C2 - 2011/// C3 - ACS National Meeting Book of Abstracts DA - 2011/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80051879079&partnerID=MN8TOARS ER - TY - CONF TI - Investigation of oxygen diffusivity within oxygen carrier in chemical looping process AU - Luo, S. AU - Sun, Z. AU - Li, F. AU - Sridhar, D. AU - Zeng, L. AU - Fan, L.-S. C2 - 2011/// C3 - 11AIChE - 2011 AIChE Annual Meeting, Conference Proceedings DA - 2011/// SP - 169 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84863396922&partnerID=MN8TOARS ER - TY - JOUR TI - Electronic Textiles: Atomic Layer Deposition of Conductive Coatings on Cotton, Paper, and Synthetic Fibers: Conductivity Analysis and Functional Chemical Sensing Using “All-Fiber” Capacitors (Adv. Funct. Mater. 11/2011) AU - Jur, Jesse. S. AU - Sweet, William J., III AU - Oldham, Christopher J. AU - Parsons, Gregory N. T2 - Advanced Functional Materials AB - Electronic functionalization of complex fiber systems is important for new applications in energy systems and electronic textiles. The cover image shows a natural fibrous material with and without conductive coating. Atomic layer deposition (ALD) of conductive coatings on natural and synthetic fibrous materials show high conductivity, and the values scale as expected with film thickness and bulk-material conductance. On page 1993, Jesse S. Jur and co-workers present an all-fiber-based capacitor formed by ALD on textiles that shows good sensing performance in several liquid media. DA - 2011/5/31/ PY - 2011/5/31/ DO - 10.1002/adfm.201190035 VL - 21 IS - 11 SP - 1948-1948 J2 - Adv. Funct. Mater. LA - en OP - SN - 1616-301X UR - http://dx.doi.org/10.1002/adfm.201190035 DB - Crossref ER - TY - JOUR TI - Correction to “Conformal Organic-Inorganic Hybrid Network Polymer Thin Films by Molecular Layer Deposition using Trimethylaluminum and Glycidol” AU - Gong,, Bo AU - Peng,, Qing AU - Parsons, Gregory N. T2 - The Journal of Physical Chemistry B AB - ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to “Conformal Organic-Inorganic Hybrid Network Polymer Thin Films by Molecular Layer Deposition using Trimethylaluminum and Glycidol”Bo Gong,, Qing Peng,, and Gregory N. Parsons*Cite this: J. Phys. Chem. B 2011, 115, 37, 11028Publication Date (Web):August 26, 2011Publication History Published online26 August 2011Published inissue 22 September 2011https://doi.org/10.1021/jp205915nCopyright © 2011 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views467Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (603 KB) Get e-Alerts Get e-Alerts DA - 2011/9/22/ PY - 2011/9/22/ DO - 10.1021/jp205915n VL - 115 IS - 37 SP - 11028-11028 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp205915n DB - Crossref ER - TY - JOUR TI - Fiber Containment for Improved Laboratory Handling and Uniform Nanocoating of Milligram Quantities of Carbon Nanotubes by Atomic Layer Deposition AU - Devine, Christina K. AU - Oldham, Christopher J. AU - Jur, Jesse S. AU - Gong, Bo AU - Parsons, Gregory N. T2 - Langmuir AB - The presence of nanostructured materials in the workplace is bringing attention to the importance of safe practices for nanomaterial handling. We explored novel fiber containment methods to improve the handling of carbon nanotube (CNT) powders in the laboratory while simultaneously allowing highly uniform and controlled atomic layer deposition (ALD) coatings on the nanotubes, down to less than 4 nm on some CNT materials. Moreover, the procedure yields uniform coatings on milligram quantities of nanotubes using a conventional viscous flow reactor system, circumventing the need for specialized fluidized bed or rotary ALD reactors for laboratory-scale studies. We explored both fiber bundles and fiber baskets as possible containment methods and conclude that the baskets are more suitable for coating studies. An extended precursor and reactant dose and soak periods allowed the gases to diffuse through the fiber containment, and the ALD coating thickness scaled linearly with the number of ALD cycles. The extended dose period produced thicker coatings compared to typical doses on CNT controls not encased in the fibers, suggesting some effects due to the extended reactant dose. Film growth was compared on a range of single-walled NTs, double-walled NTs, and acid-functionalized multiwalled NTs, and we found that ultrathin coatings were most readily controlled on the multiwalled NTs. DA - 2011/12/6/ PY - 2011/12/6/ DO - 10.1021/la202677u VL - 27 IS - 23 SP - 14497-14507 J2 - Langmuir LA - en OP - SN - 0743-7463 1520-5827 UR - http://dx.doi.org/10.1021/la202677u DB - Crossref ER - TY - CONF TI - SiNx Charge Trap Nonvolatile Memory Based on ZnO Thin Film Transistor Prepared by Atomic Layer Deposition AU - Kim, E. AU - Lee, K. AU - Kim, D. AU - Parsons, G. N. AU - Park, K. AU - Ihm, Jisoon AU - Cheong, Hyeonsik T2 - PHYSICS OF SEMICONDUCTORS: 30th International Conference on the Physics of Semiconductors AB - We fabricated a nonvolatile thin film transistor (TFT) memory with SiNx charge traps using a ZnO thin film as an active channel layer. The thin film of ZnO was deposited by using atomic layer deposition process at TALD = 125 °C. The ZnO films were investigated by X‐ray diffraction and X‐ray photoemission measurements. The electrical measurements of the nonvolatile TFT memory showed a field‐effect mobility of 2.95 cm2 V−1 s−1, a threshold voltage of −7.24 V, a subthreshold swing of 1.7 V/dec, and an on/off ratio of 3.4×105. From the C‐V measurement, the memory window of 2 V was obtained. C2 - 2011/// C3 - DA - 2011/// DO - 10.1063/1.3666301 PB - AIP UR - http://dx.doi.org/10.1063/1.3666301 DB - Crossref KW - ZnO KW - thin film transistor KW - nonvolatile memory KW - memory window KW - transparent/flexible device ER - TY - JOUR TI - Order-Disorder Phase Conversion of FePt Nanoparticles for Ultrahigh-Density Magnetic Recording AU - Johnston-Peck, A AU - Scarel, G AU - Wang, J AU - Parsons, G AU - Tracy, J T2 - Microscopy and Microanalysis AB - Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011. DA - 2011/7// PY - 2011/7// DO - 10.1017/S1431927611010026 VL - 17 IS - S2 SP - 1830-1831 J2 - Microsc Microanal LA - en OP - SN - 1431-9276 1435-8115 UR - http://dx.doi.org/10.1017/S1431927611010026 DB - Crossref ER - TY - JOUR TI - Complete Genome Sequences for the Anaerobic, Extremely Thermophilic Plant Biomass-Degrading Bacteria Caldicellulosiruptor hydrothermalis , Caldicellulosiruptor kristjanssonii , Caldicellulosiruptor kronotskyensis , Caldicellulosiruptor owensensis , and Caldicellulosiruptor lactoaceticus AU - Blumer-Schuette, Sara E. AU - Ozdemir, Inci AU - Mistry, Dhaval AU - Lucas, Susan AU - Lapidus, Alla AU - Cheng, Jan-Fang AU - Goodwin, Lynne A. AU - Pitluck, Samuel AU - Land, Miriam L. AU - Hauser, Loren J. AU - Woyke, Tanja AU - Mikhailova, Natalia AU - Pati, Amrita AU - Kyrpides, Nikos C. AU - Ivanova, Natalia AU - Detter, John C. AU - Walston-Davenport, Karen AU - Han, Shunsheng AU - Adams, Michael W. W. AU - Kelly, Robert M. T2 - Journal of Bacteriology AB - ABSTRACT The genus Caldicellulosiruptor contains the most thermophilic, plant biomass-degrading bacteria isolated to date. Previously, genome sequences from three cellulolytic members of this genus were reported ( C. saccharolyticus , C. bescii , and C. obsidiansis ). To further explore the physiological and biochemical basis for polysaccharide degradation within this genus, five additional genomes were sequenced: C. hydrothermalis , C. kristjanssonii , C. kronotskyensis , C. lactoaceticus , and C. owensensis . Taken together, the seven completed and one draft-phase Caldicellulosiruptor genomes suggest that, while central metabolism is highly conserved, significant differences in glycoside hydrolase inventories and numbers of carbohydrate transporters exist, a finding which likely relates to variability observed in plant biomass degradation capacity. DA - 2011/3/15/ PY - 2011/3/15/ DO - 10.1128/jb.01515-10 VL - 193 IS - 6 SP - 1483-1484 J2 - J Bacteriol LA - en OP - SN - 0021-9193 1098-5530 UR - http://dx.doi.org/10.1128/jb.01515-10 DB - Crossref ER - TY - JOUR TI - Quantitative models of signal transduction networks AU - Cirit, Murat AU - Haugh, Jason M. T2 - Communicative & Integrative Biology AB - Receptor-mediated signal transduction networks, comprised of multiple biochemical pathways, control cell responses and are therefore central to normal and aberrant physiological processes. An appreciation for the inherent complexities of these networks has matured in recent years, to the point where it is now apparent that experimental measurements will need to be combined with computational modeling and analysis to best interpret and predict how individual mechanisms (protein-protein interactions, enzymatic reactions, etc.) are integrated at the network level. To progress along these lines, there is a major barrier to overcome: although a deep mechanistic understanding of signal transduction has been achieved, data sets of a suitably quantitative nature are still lacking. Based on our efforts to systematically acquire and analyze such measurements, we contend that the level of detail in models of signaling networks ought to be limited by the availability of quantitative data, rather than by the much greater availability of qualitative information about signaling interactions. Although this approach is sensible from a data-driven modeling perspective, it is controversial because it gives the false impression that molecular-level details are being ignored. DA - 2011/5// PY - 2011/5// DO - 10.4161/cib.4.3.15149 VL - 4 IS - 3 SP - 353-356 ER - TY - JOUR TI - Re-engineering multicloning sites for function and convenience AU - Crook, N. C. AU - Freeman, E. S. AU - Alper, H. S. T2 - Nucleic Acids Research AB - Multicloning sites (MCSs) in standard expression vectors are widely used and thought to be benign, non-interacting elements that exist for mere convenience. However, MCSs impose a necessary distance between promoter elements and genes of interest. As a result, the choice of cloning site defines the genetic context and may introduce significant mRNA secondary structure in the 5'-untranslated region leading to strong translation inhibition. Here, we demonstrate the first performance-based assessment of MCSs in yeast, showing that commonly used MCSs can induce dramatic reductions in protein expression, and that this inhibition is highly promoter and gene dependent. In response, we develop and apply a novel predictive model of structure-based translation inhibition to design improved MCSs for significantly higher and more consistent protein expression. In doing so, we were able to minimize the inhibitory effects of MCSs with the yeast TEF, CYC and GPD promoters. These results highlight the non-interchangeable nature of biological parts and represent the first complete, global redesign of a genetic circuit of such widespread importance as a multicloning site. The improved translational control offered by these designed MCSs is paramount to obtaining high titers of heterologous proteins in eukaryotes and to enabling precise control of genetic circuits. DA - 2011/5// PY - 2011/5// DO - 10.1093/nar/gkr346 VL - 39 IS - 14 SP - e92-e92 ER - TY - JOUR TI - Using Flux Balance Analysis to Guide Microbial Metabolic Engineering AU - Curran, Kathleen A. AU - Crook, Nathan C. AU - Alper, Hal S. T2 - Microbial Metabolic Engineering AB - Metabolic engineers modify biological systems through the use of modern molecular biology tools in order to obtain desired phenotypes. However, due to the extreme complexity and interconnectedness of metabolism in all organisms, it is often difficult to a priori predict which changes will yield the optimal results. Flux balance analysis (FBA) is a mathematical approach that uses a genomic-scale metabolic network models to afford in silico prediction and optimization of metabolic changes. In particular, a genome-scale approach can help select gene targets for knockout and overexpression. This approach can be used to help expedite the strain engineering process. Here, we give an introduction to the use of FBA and provide details for its implementation in a microbial metabolic engineering context. DA - 2011/11// PY - 2011/11// DO - 10.1007/978-1-61779-483-4_13 SP - 197-216 KW - Flux balance analysis KW - MOMA KW - Genomic-scale metabolic model KW - Metabolic engineering KW - Strain engineering ER - TY - JOUR TI - Real-time in situ rheology of alginate hydrogel photocrosslinking AU - Bonino, Christopher A. AU - Samorezov, Julia E. AU - Jeon, Oju AU - Alsberg, Eben AU - Khan, Saad A. T2 - Soft Matter AB - The reaction dynamics of biodegradable, photocrosslinkable sodium alginate hydrogels are studied by in situ, dynamic rheology. Alginate, chemically-modified with methacrylate groups, crosslinks by ultraviolet (UV) light exposure in the presence of a photoinitiator. The gel formation is monitored during UV irradiation from a light emitting diode (LED) bottom plate fixture on the rheometer. Material properties of the hydrogels, including gel points and relaxation exponent, are evaluated using the Winter-Chambon criteria. We also report a new, complementary empirical method for determining the gel point from the reduction in sample strain at the onset of gelation, via monitoring the strain curve. In addition, the crosslinking dynamics and hydrogel moduli are altered by changing the UV irradiation intensities (3–15 mW cm−2) and degree of methacrylation (5–25%). Dynamic rheological measurements of hydrogels as described in this paper are a potentially powerful tool to elucidate the dynamics of gelation and predict mechanical properties. This technique may aid in the design of polymer formulations with light-reactive chemical species, which have tunable properties that can be matched to a range of applications, including regenerative medicine. DA - 2011/// PY - 2011/// DO - 10.1039/c1sm06109g VL - 7 IS - 24 SP - 11510-11517 SN - 1744-683X 1744-6848 UR - http://dx.doi.org/10.1039/c1sm06109g ER - TY - JOUR TI - Electrospinning alginate-based nanofibers: From blends to crosslinked low molecular weight alginate-only systems AU - Bonino, Christopher A. AU - Krebs, Melissa D. AU - Saquing, Carl D. AU - Jeong, Sung In AU - Shearer, Kimberly L. AU - Alsberg, Eben AU - Khan, Saad A. T2 - Carbohydrate Polymers AB - We report here preparation of nanofibers containing alginate using two different molecular weights (MWs): 37 kDa and 196 kDa. Low MW alginates are attractive for in vivo tissue scaffolds where degradation and clearance from the body are desirable, whereas higher MW alginates are amenable for topical use as wound coverage because of its better mechanical properties. We use polyethylene oxide (PEO) as a carrier material to aid in electrospinning, and relate the solution properties, including entanglement concentration, relaxation time, conductivity, and surface tension, to their ability to be electrospun. In addition, we examine an FDA-approved, nonionic surfactant as a route to enhancing the alginate–PEO ratio (>80:20), and less toxic alternative to Triton X-100 surfactant. Finally, alginate-only nanofibers that are also water-insoluble are obtained by crosslinking the electrospun fibers with calcium and subsequently removing the PEO and surfactants by soaking the nanofibers in water. DA - 2011/4// PY - 2011/4// DO - 10.1016/j.carbpol.2011.02.002 VL - 85 IS - 1 SP - 111-119 J2 - Carbohydrate Polymers LA - en OP - SN - 0144-8617 UR - http://dx.doi.org/10.1016/j.carbpol.2011.02.002 DB - Crossref KW - Biomaterials KW - Nanotechnology KW - Nanofibers KW - Electrospinning KW - Alginate KW - Pluronic surfactant ER - TY - JOUR TI - Long-Range Alignment of Gold Nanorods in Electrospun Polymer Nano/Microfibers AU - Roskov, Kristen E. AU - Kozek, Krystian A. AU - Wu, Wei-Chen AU - Chhetri, Raghav K. AU - Oldenburg, Amy L. AU - Spontak, Richard J. AU - Tracy, Joseph B. T2 - Langmuir AB - In this study, a scalable fabrication technique for controlling and maintaining the nanoscale orientation of gold nanorods (GNRs) with long-range macroscale order has been achieved through electrospinning. The volume fraction of GNRs with an average aspect ratio of 3.1 is varied from 0.006 to 0.045 in aqueous poly(ethylene oxide) solutions to generate electrospun fibers possessing different GNR concentrations and measuring 40-3000 nm in diameter. The GNRs within these fibers exhibit excellent alignment with their longitudinal axis parallel to the fiber axis n. According to microscopy analysis, the average deviant angle between the GNR axis and n increases modestly from 3.8 to 13.3° as the fiber diameter increases. Complementary electron diffraction measurements confirm preferred orientation of the {100} GNR planes. Optical absorbance spectroscopy measurements reveal that the longitudinal surface plasmon resonance bands of the aligned GNRs depend on the polarization angle and that maximum extinction occurs when the polarization is parallel to n. DA - 2011/12/6/ PY - 2011/12/6/ DO - 10.1021/la2021066 VL - 27 IS - 23 SP - 13965-13969 J2 - Langmuir LA - en OP - SN - 0743-7463 1520-5827 UR - http://dx.doi.org/10.1021/la2021066 DB - Crossref ER - TY - JOUR TI - Permeability control in stimulus-responsive colloidosomes AU - San Miguel, Adriana AU - Behrens, Sven H. T2 - Soft Matter AB - Self-assembly of colloidal particles in the liquid interface of double emulsion droplets can be used to fabricate “colloidosome” microcapsules, which have great potential as vehicles for the controlled delivery of drugs or other cargoes. Here we present a novel class of aqueous core colloidosomes that combine the benefit of low capsule permeability (good cargo retention) with the option of a stimulus-triggered fast release in a target environment. Complete or partial dissolution of the capsule walls in response to a mild pH change is achieved in each case through the use of responsive particles made from polymers with pH-switchable solubility. We demonstrate three methods of controlling the capsule permeability prior to release while maintaining the intended response to the release trigger. DA - 2011/// PY - 2011/// DO - 10.1039/c0sm01107j VL - 7 IS - 5 SP - 1948-1956 J2 - Soft Matter LA - en OP - SN - 1744-683X 1744-6848 UR - http://dx.doi.org/10.1039/c0sm01107j DB - Crossref ER - TY - JOUR TI - Correction to “Correlating Aggregation Kinetics and Stationary Diffusion in Protein–Sodium Salt Systems Observed with Dynamic Light Scattering” AU - Rubin, Jonathan AU - San Miguel, Adriana AU - Bommarius, Andreas S. AU - Behrens, Sven H. T2 - The Journal of Physical Chemistry B AB - ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to “Correlating Aggregation Kinetics and Stationary Diffusion in Protein–Sodium Salt Systems Observed with Dynamic Light Scattering”Jonathan Rubin, Adriana San Miguel, Andreas S. Bommarius*, and Sven H. BehrensCite this: J. Phys. Chem. B 2011, 115, 36, 10778Publication Date (Web):August 18, 2011Publication History Published online18 August 2011Published inissue 15 September 2011https://doi.org/10.1021/jp206633aCopyright © 2011 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views336Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts DA - 2011/9/15/ PY - 2011/9/15/ DO - 10.1021/jp206633a VL - 115 IS - 36 SP - 10778-10778 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp206633a DB - Crossref ER - TY - JOUR TI - An Evolved Adeno-associated Viral Variant Enhances Gene Delivery and Gene Targeting in Neural Stem Cells AU - Jang, Jae-Hyung AU - Koerber, James T AU - Kim, Jung-Suk AU - Asuri, Prashanth AU - Vazin, Tandis AU - Bartel, Melissa AU - Keung, Albert AU - Kwon, Inchan AU - Park, Kook In AU - Schaffer, David V T2 - Molecular Therapy AB - Gene delivery to, and gene targeting in, stem cells would be a highly enabling technology for basic science and biomedical application. Adeno-associated viral (AAV) vectors have demonstrated the capacity for efficient delivery to numerous cells, but their application to stem cells has been limited by low transduction efficiency. Due to their considerable advantages, however, engineering AAV delivery systems to enhance gene delivery to stem cells may have an impact in stem cell biology and therapy. Therefore, using several diverse AAV capsid libraries-including randomly mutagenized, DNA shuffled, and random peptide insertion variants-we applied directed evolution to create a "designer" AAV vector with enhanced delivery efficiency for neural stem cells (NSCs). A novel AAV variant, carrying an insertion of a selected peptide sequence on the surface of the threefold spike within the heparin-binding site, emerged from this evolution. Importantly, this evolved AAV variant mediated efficient gene delivery to rat, mouse, and human NSCs, as well as efficient gene targeting within adult NSCs, and it is thus promising for applications ranging from basic stem cell biology to clinical translation. DA - 2011/4// PY - 2011/4// DO - 10.1038/mt.2010.287 VL - 19 IS - 4 SP - 667-675 J2 - Molecular Therapy LA - en OP - SN - 1525-0016 UR - http://dx.doi.org/10.1038/mt.2010.287 DB - Crossref ER - TY - JOUR TI - Rho GTPases Mediate the Mechanosensitive Lineage Commitment of Neural Stem Cells AU - Keung, Albert J. AU - de Juan-Pardo, Elena M. AU - Schaffer, David V. AU - Kumar, Sanjay T2 - STEM CELLS AB - Adult neural stem cells (NSCs) play important roles in learning and memory and are negatively impacted by neurological disease. It is known that biochemical and genetic factors regulate self-renewal and differentiation, and it has recently been suggested that mechanical and solid-state cues, such as extracellular matrix (ECM) stiffness, can also regulate the functions of NSCs and other stem cell types. However, relatively little is known of the molecular mechanisms through which stem cells transduce mechanical inputs into fate decisions, the extent to which mechanical inputs instruct fate decisions versus select for or against lineage-committed blast populations, or the in vivo relevance of mechanotransductive signaling molecules in native stem cell niches. Here we demonstrate that ECM-derived mechanical signals act through Rho GTPases to activate the cellular contractility machinery in a key early window during differentiation to regulate NSC lineage commitment. Furthermore, culturing NSCs on increasingly stiff ECMs enhances RhoA and Cdc42 activation, increases NSC stiffness, and suppresses neurogenesis. Likewise, inhibiting RhoA and Cdc42 or downstream regulators of cellular contractility rescues NSCs from stiff matrix- and Rho GTPase-induced neurosuppression. Importantly, Rho GTPase expression and ECM stiffness do not alter proliferation or apoptosis rates indicating that an instructive rather than selective mechanism modulates lineage distributions. Finally, in the adult brain, RhoA activation in hippocampal progenitors suppresses neurogenesis, analogous to its effect in vitro. These results establish Rho GTPase-based mechanotransduction and cellular stiffness as biophysical regulators of NSC fate in vitro and RhoA as an important regulatory protein in the hippocampal stem cell niche. DA - 2011/10/25/ PY - 2011/10/25/ DO - 10.1002/stem.746 VL - 29 IS - 11 SP - 1886-1897 J2 - STEM CELLS LA - en OP - SN - 1066-5099 UR - http://dx.doi.org/10.1002/stem.746 DB - Crossref KW - Neural stem cells KW - Cellular mechanotransduction KW - Rho GTP-binding proteins KW - Adipose stem cells KW - Extracellular matrix KW - Elastic modulus ER - TY - JOUR TI - The influence of ZnO, CeO2 and ZrO2 on nanoparticle-oxide-supported palladium oxide catalysts for the oxidative coupling of 4-methylpyridine AU - Dodson, Justin J. AU - Neal, Luke M. AU - Hagelin-Weaver, Helena E. T2 - Journal of Molecular Catalysis A: Chemical AB - Abstract 4,4′-Dimethyl-2,2′-bipyridine is a useful but expensive chelating agent. Having more efficient routes to the synthesis of this compound would be advantageous to the wide-spread use of this fine chemical. In this work, the effects of adding strongly interacting oxides (ZnO, CeO 2 , and ZrO 2 ) to PdO catalysts supported on high surface area n-Al 2 O 3 (+), n-MgO, and n-TiO 2 prepared via co- and sequential precipitation were investigated. The product yields obtained from these catalysts in the oxidative coupling of 4-methylpyridine are dependent on the additive, the support, and preparation method. Evidently, these are complex catalytic systems in that the PdO–additive and PdO–support interactions must be right to promote product formation while preventing palladium leaching and support or additive migration over the active Pd/PdO sites. Although PdO/n-ZnO catalysts are reasonably active in the coupling reaction, ZnO addition to PdO catalysts supported on n-Al 2 O 3 (+), n-MgO, or n-TiO 2 does not increase the yield in any case. CeO 2 and ZrO 2 can increase the product yields in the reaction depending on the support used. Due to strong PdO–CeO 2 interactions, the addition of CeO 2 in some cases results in CeO x -migration and coverage of active PdO species or disrupts favorable PdO–support interactions leading to Pd leaching. Therefore, ZrO 2 is the better additive with co-precipitated PdO/ZrO 2 /n-Al 2 O 3 (+) consistently producing yields in excess of 3.4 ± 0.1 g/g catalyst which is 36% higher than the 2.5 ± 0.16 g/g catalyst obtained from the PdO/n-Al 2 O 3 (+) (5 wt% Pd), the best catalyst previously reported for this reaction. DA - 2011/5// PY - 2011/5// DO - 10.1016/j.molcata.2011.03.022 VL - 341 IS - 1-2 SP - 42-50 J2 - Journal of Molecular Catalysis A: Chemical LA - en OP - SN - 1381-1169 UR - http://dx.doi.org/10.1016/j.molcata.2011.03.022 DB - Crossref KW - Palladium oxide KW - CeO2 KW - ZrO2 and ZnO additive oxides KW - Nanoparticle oxide supports KW - 4-Methylpyridine KW - Aromatic coupling ER - TY - JOUR TI - Characterization of palladium oxide catalysts supported on nanoparticle metal oxides for the oxidative coupling of 4-methylpyridine AU - Neal, Luke M. AU - Everett, Michael L. AU - Hoflund, Gar B. AU - Hagelin-Weaver, Helena E. T2 - Journal of Molecular Catalysis A: Chemical AB - Palladium catalysts supported on various metal oxides were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) to investigate why these catalysts do not show any correlation between the measured Pd surface area and the catalytic activity for the oxidative coupling of 4-methylpyridine to 4,4′-dimethyl-2,2′-bipyridine. The XPS data confirm the classification of n-Al2O3(+), n-MgO and p-SiO2 as non-interacting supports, since the Pd 3d5/2 binding energy (BE) of palladium on these supports is 336.1 eV, consistent with bulk PdO. In contrast, catalysts supported on p-TiO2, n-ZnO, n-ZrO2, n-ZrO2(CeO2), and n-CeO2 have Pd 3d5/2 BEs ranging from 336.3 to 337.4 eV, which reveal varying degrees of metal-support interactions. Metal support interactions leading to electron deficient Pd2+ species are likely beneficial for the reaction due to a facilitated C–H insertion step. While both the PdO/p-TiO2 and PdO/n-TiO2 catalysts have a Pd 3d BE of 336.3 eV, their differences in activity can be attributed to (1) the PdO/n-TiO2 catalyst as prepared having a significantly higher number of hydroxyl groups on the surface compared with the PdO/p-TiO2 catalyst, and (2) the p-TiO2 support being crystalline with an anatase phase, while the n-TiO2 support is nearly amorphous. The presence of surface hydroxyl groups before reaction could hinder the first C–H activation step, and an anatase phase of the support can result in more favorable palladium-support interactions compared with an amorphous TiO2. The XPS data also indicates that while Pd-support interactions are beneficial, very strong interactions, such as in the case of CeO2, can lead to migration of the support over Pd, which reduces the Pd surface area and explains the lower than expected activity of the PdO/n-CeO2 catalyst. On some supports in this study leaching may occur during the reaction, but the characterization data indicate that other factors of catalyst deactivation are more important. XRD reveals that the complete reduction of the PdO particles on the surface is very fast compared to the reaction time. This observation explains why reducible supports with mobile oxygen are beneficial in this reaction. These supports can facilitate the reoxidation of palladium due to strong metal-support interactions. Migration of the support over the active palladium species is another deactivation pathway that appears to be more severe than leaching on these catalysts. DA - 2011/2// PY - 2011/2// DO - 10.1016/j.molcata.2010.11.036 VL - 335 IS - 1-2 SP - 210-221 J2 - Journal of Molecular Catalysis A: Chemical LA - en OP - SN - 1381-1169 UR - http://dx.doi.org/10.1016/j.molcata.2010.11.036 DB - Crossref KW - Palladium KW - Nanoparticle oxide KW - 4-Methylpyridine KW - C-H activation KW - Aromatic coupling ER - TY - JOUR TI - The Base-Pairing RNA Spot 42 Participates in a Multioutput Feedforward Loop to Help Enact Catabolite Repression in Escherichia coli AU - Beisel, Chase L. AU - Storz, Gisela T2 - Molecular Cell AB - Bacteria selectively consume some carbon sources over others through a regulatory mechanism termed catabolite repression. Here, we show that the base-pairing RNA Spot 42 plays a broad role in catabolite repression in Escherichia coli by directly repressing genes involved in central and secondary metabolism, redox balancing, and the consumption of diverse nonpreferred carbon sources. Many of the genes repressed by Spot 42 are transcriptionally activated by the global regulator CRP. Since CRP represses Spot 42, these regulators participate in a specific regulatory circuit called a multioutput feedforward loop. We found that this loop can reduce leaky expression of target genes in the presence of glucose and can maintain repression of target genes under changing nutrient conditions. Our results suggest that base-pairing RNAs in feedforward loops can help shape the steady-state levels and dynamics of gene expression. DA - 2011/2// PY - 2011/2// DO - 10.1016/j.molcel.2010.12.027 VL - 41 IS - 3 SP - 286-297 J2 - Molecular Cell LA - en OP - SN - 1097-2765 UR - http://dx.doi.org/10.1016/j.molcel.2010.12.027 DB - Crossref ER - TY - JOUR TI - Size-dependent regulation of dorsal-ventral patterning in the early Drosophila embryo AU - Nahmad, Marcos AU - Reeves, Gregory AU - Stathopoulos, Angelike T2 - Developmental Biology DA - 2011/8// PY - 2011/8// DO - 10.1016/j.ydbio.2011.05.061 VL - 356 IS - 1 SP - 119 J2 - Developmental Biology LA - en OP - SN - 0012-1606 UR - http://dx.doi.org/10.1016/j.ydbio.2011.05.061 DB - Crossref ER - TY - JOUR TI - Engineering and modeling of thin, adhesive, microbial biocatalytic coatings for high intensity oxidations in multi-phase microchannel bioreactors AU - Fidaleo, M. AU - Flickinger, M.C. T2 - Chemical Engineering Science AB - A model-based investigation of the reactivity of a multi-phase microchannel bioreactor for the oxidation of d-sorbitol to l-sorbose by viable Gluconobacter oxydans entrapped in an adhesive, bilayer, and nano-porous latex coating has been performed. Using kinetics and mass-transfer information from literature, the overall productivity of a single microchannel was determined. For liquid and gas superficial velocities typical for monoliths and channel diameters smaller than 1000 μm, volumetric l-sorbose formation rates larger than 30 g l−1 h−1 were predicted. Since the system was approximately kinetically controlled any effort to increase the coating reactivity, for example by using thinner topcoats or improving cell viability should result in a further increase of the overall reactivity. These modeling studies should provide the basis for engineering of channel geometry, biocatalytic coating nano-porosity and thickness, coating stability, optimal reactivity and multi-phase channel flow properties for future microchannel bioreactors for high intensity microbial oxidations. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.ces.2011.02.020 VL - 66 IS - 14 SP - 3251-3257 J2 - Chemical Engineering Science LA - en OP - SN - 0009-2509 UR - http://dx.doi.org/10.1016/j.ces.2011.02.020 DB - Crossref KW - Biochemical engineering KW - Bioreactors KW - Immobilization of Gluconobacter oxydans KW - Microchannel bioreactors KW - Mathematical modeling KW - Multi-phase reactors ER - TY - JOUR TI - Electrospun Nanofibers for Energy Storage T2 - Aatcc Review DA - 2011/// PY - 2011/// UR - https://publons.com/publon/7178353/ ER - TY - JOUR TI - PRINT: A Novel Platform Toward Shape and Size Specific Nanoparticle Theranostics AU - Perry, Jillian L. AU - Herlihy, Kevin P. AU - Napier, Mary E. AU - DeSimone, Joseph M. T2 - Accounts of Chemical Research AB - Nanotheranostics represents the next generation of medicine, fusing nanotechnology, therapeutics, and diagnostics. By integrating therapeutic and imaging agents into one nanoparticle, this new treatment strategy has the potential not only to detect and diagnose disease but also to treat and monitor the therapeutic response. This capability could have a profound impact in both the research setting as well as in a clinical setting. In the research setting, such a capability will allow research scientists to rapidly assess the performance of new therapeutics in an effort to iterate their designs for increased therapeutic index and efficacy. In the clinical setting, theranostics offers the ability to determine whether patients enrolling in clinical trials are responding, or are expected to respond, to a given therapy based on the hypothesis associated with the biological mechanisms being tested. If not, patients can be more quickly removed from the clinical trial and shifted to other therapeutic options. To be effective, these theranostic agents must be highly site specific. Optimally, they will carry relevant cargo, demonstrate controlled release of that cargo, and include imaging probes with a high signal-to-noise ratio.There are many biological barriers in the human body that challenge the efficacy of nanoparticle delivery vehicles. These barriers include, but are not limited to, the walls of blood vessels, the physical entrapment of particles in organs, and the removal of particles by phagocytic cells. The rapid clearance of circulating particles during systemic delivery is a major challenge; current research seeks to define key design parameters that govern the performance of nanocarriers, such as size, surface chemistry, elasticity, and shape. The effect of particle size and surface chemistry on in vivo biodistribution of nanocarriers has been extensively studied, and general guidelines have been established. Recently it has been documented that shape and elasticity can have a profound effect on the behavior of delivery vehicles. Thus, having the ability to independently control shape, size, matrix, surface chemistry, and modulus is crucial for designing successful delivery agents.In this Account, we describe the use of particle replication in nonwetting templates (PRINT) to fabricate shape- and size-specific microparticles and nanoparticles. A particular strength of the PRINT method is that it affords precise control over shape, size, surface chemistry, and modulus. We have demonstrated the loading of PRINT particles with chemotherapeutics, magnetic resonance contrast agents, and fluorophores. The surface properties of the PRINT particles can be easily modified with “stealth” poly(ethylene glycol) chains to increase blood circulation time, with targeting moieties for targeted delivery or with radiolabels for nuclear imaging. These particles have tremendous potential for applications in nanomedicine and diagnostics. DA - 2011/10/18/ PY - 2011/10/18/ DO - 10.1021/ar2000315 VL - 44 IS - 10 SP - 990-998 J2 - Acc. Chem. Res. LA - en OP - SN - 0001-4842 1520-4898 UR - http://dx.doi.org/10.1021/ar2000315 DB - Crossref ER - TY - JOUR TI - Biomimetic microlens array with antireflective “moth-eye” surface AU - Ko, Doo-Hyun AU - Tumbleston, John R. AU - Henderson, Kevin J. AU - Euliss, Larken E. AU - DeSimone, Joseph M. AU - Lopez, Rene AU - Samulski, Edward T. T2 - Soft Matter AB - We report a replication route to non-planar, three dimensional microlens arrays with an antireflective surface nanopattern. Our methodology uses the surface topography of the Attacus atlas moth's compound eye and a soft lithographic technique to fabricate topographically faithful moulds that, in turn, are used to reproducibly replicate the original eye surface with nanoscale fidelity. In addition to antireflection, the resulting poly(urethane) replica with its “moth-eye” nanopattern also exhibits increased hydrophobicity relative to the unpatterned polymer. The materials flexibility of the perfluoropolyether mould fabricated viareplica moulding enables, for example, the embossing of antireflective nanopatterns in the photoactive materials of organic solar cells. DA - 2011/// PY - 2011/// DO - 10.1039/c1sm05302g VL - 7 IS - 14 SP - 6404 J2 - Soft Matter LA - en OP - SN - 1744-683X 1744-6848 UR - http://dx.doi.org/10.1039/c1sm05302g DB - Crossref ER - TY - JOUR TI - Shear thickening and jamming in densely packed suspensions of different particle shapes AU - Brown, Eric AU - Zhang, Hanjun AU - Forman, Nicole A. AU - Maynor, Benjamin W. AU - Betts, Douglas E. AU - DeSimone, Joseph M. AU - Jaeger, Heinrich M. T2 - Physical Review E AB - We investigated the effects of particle shape on shear thickening in densely packed suspensions. Rods of different aspect ratios and nonconvex hooked rods were fabricated. Viscosity curves and normal stresses were measured using a rheometer for a wide range of packing fractions for each shape. Suspensions of each shape exhibit qualitatively similar discontinuous shear thickening. The logarithmic slope of the stress vs shear rate increases dramatically with packing fraction and diverges at a critical packing fraction ${\ensuremath{\varphi}}_{c}$ which depends on particle shape. The packing fraction dependence of the viscosity curves for different convex shapes can be collapsed when the packing fraction is normalized by ${\ensuremath{\varphi}}_{c}$. Intriguingly, viscosity curves for nonconvex particles do not collapse on the same set as convex particles, showing strong shear thickening over a wider range of packing fraction. The value of ${\ensuremath{\varphi}}_{c}$ is found to coincide with the onset of a yield stress at the jamming transition, suggesting the jamming transition also controls shear thickening. The yield stress is found to correspond with trapped air in the suspensions, and the scale of the stress can be attributed to interfacial tension forces which dramatically increase above ${\ensuremath{\varphi}}_{c}$ due to the geometric constraints of jamming. Using this connection we show that the jamming transition can be identified by simply looking at the surface of suspensions. The relationship between shear and normal stresses is found to be linear in both the shear thickening and jammed regimes, indicating that the shear stresses come from friction. In the limit of zero shear rate, normal stresses pull the rheometer plates together due to the surface tension of the liquid below ${\ensuremath{\varphi}}_{c}$, but push the rheometer plates apart due to jamming above ${\ensuremath{\varphi}}_{c}$. DA - 2011/9/28/ PY - 2011/9/28/ DO - 10.1103/physreve.84.031408 VL - 84 IS - 3 J2 - Phys. Rev. E LA - en OP - SN - 1539-3755 1550-2376 UR - http://dx.doi.org/10.1103/physreve.84.031408 DB - Crossref ER - TY - JOUR TI - Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings AU - Wang, Yapei AU - Pitet, Louis M. AU - Finlay, John A. AU - Brewer, Lenora H. AU - Cone, Gemma AU - Betts, Douglas E. AU - Callow, Maureen E. AU - Callow, James A. AU - Wendt, Dean E. AU - Hillmyer, Marc A. AU - DeSimone, Joseph M. T2 - Biofouling AB - The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M(w) = 1500 g mol(-1)) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M(w) = 300, 475, 1100 g mol(-1)), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2. DA - 2011/11/16/ PY - 2011/11/16/ DO - 10.1080/08927014.2011.629344 VL - 27 IS - 10 SP - 1139-1150 J2 - Biofouling LA - en OP - SN - 0892-7014 1029-2454 UR - http://dx.doi.org/10.1080/08927014.2011.629344 DB - Crossref KW - amphiphilic coating KW - adhesion KW - antifouling KW - fouling-release KW - perfluoropolyether ER - TY - JOUR TI - Relieving PEGylation AU - Parrott, Matthew C. AU - DeSimone, Joseph M. T2 - Nature Chemistry AB - A new type of protein–polymer conjugate provides improved stability without detrimentally affecting bioactivity, and thus offers great potential for the development of new peptide-based drugs. DA - 2011/12/15/ PY - 2011/12/15/ DO - 10.1038/nchem.1230 VL - 4 IS - 1 SP - 13-14 J2 - Nature Chem LA - en OP - SN - 1755-4330 1755-4349 UR - http://dx.doi.org/10.1038/nchem.1230 DB - Crossref ER - TY - JOUR TI - Institutional Profile: The Carolina Center of Cancer Nanotechnology Excellence: past accomplishments and future perspectives AU - Juliano, Rudy L AU - Sunnarborg, Susan AU - DeSimone, Joseph AU - Haroon, Zishan T2 - Nanomedicine AB - The Carolina Center of Cancer Nanotechnology Excellence (C-CCNE) is funded by the National Cancer Institute and is based at the University of North Carolina. The C-CCNE features interactions between physical and biological scientists in a series of projects and cores that work together to quickly harness innovations in nanotechnology for the early diagnosis and treatment of cancer. Two key focus areas of the C-CCNE are, first, the selective delivery of drugs and imaging agents utilizing advanced nanoparticle technology, and second, novel approaches to imaging and radiotherapy utilizing carbon nanotube-based x-ray sources. DA - 2011/1// PY - 2011/1// DO - 10.2217/nnm.10.142 VL - 6 IS - 1 SP - 19-24 J2 - Nanomedicine LA - en OP - SN - 1743-5889 1748-6963 UR - http://dx.doi.org/10.2217/nnm.10.142 DB - Crossref ER - TY - JOUR TI - Influence of the Fluid-to-Film Transition on Photophysical Properties of MLCT Excited States in a Polymerizable Dimethacrylate Fluid AU - Knight, Troy E. AU - Goldstein, Anna P. AU - Brennaman, M. Kyle AU - Cardolaccia, Thomas AU - Pandya, Ashish AU - DeSimone, Joseph M. AU - Meyer, Thomas J. T2 - The Journal of Physical Chemistry B AB - Photophysical properties of the salts [Ru(bpy)(3)](p-Tos)(2), [Ru(dmb)(3)](PF(6))(2), [Ru(vbpy)(3)](PF(6))(2), and [Ru(phen)(3)](p-Tos)(2) (bpy = 2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, vbpy = 4-methyl-4'-vinyl-2,2'-bipyridine, phen = 1,10-phenanthroline, and p-Tos = p-toluene sulfonate) in fluid and film polyethylene glycol dimethacrylate containing nine ethylene glycol spacers (PEG-DMA550) are reported. MLCT absorption energies and bandshapes are similar in fluid and film PEG-DMA550 pointing to similar local dielectric environments, presumably dominated by the polar acrylate groups. Emission energies and excited-to-ground state 0-0 energy gaps (E(0)), determined by emission spectral fitting, are blue-shifted, and band-widths-at-half height (Δv(0,1/2)) decreased, due to an expected "rigid medium effect" in PEG-DMA550 film. The extent of loss of medium dipole reorientation in the rigid environment, and the increased emission energies in the film, resulted in enhanced emission quantum yields and excited state lifetimes in accordance with the energy gap law. The "rigid medium effect" in PEG-DMA550 is less pronounced than in films of poly(methyl methacrylate) (PMMA) pointing to a more fluid-like local environment presumably arising from the ethylene glycol linker spacers in PEG-DMA550. Comparison of the absorption, emission, emission spectral fitting, and emission lifetime results for [Ru(dmb)(3)](PF(6))(2) and [Ru(vbpy)(3)](PF(6))(2) shows that the vinyl groups of vbpy copolymerize with PEG-DMA550 covalently incorporating Ru(vbpy)(3)(2+) as a cross-linker into the polymer network. The most dramatic effect of the fluid-to-film transition is seen in the emission lifetime data for [Ru(phen)(3)](p-Tos)(2), with an increase of ~3 in the PEG-DMA550 film. Ru(phen)(3)(2+) cations appear to occupy a low symmetry site in the films probably close to the polar acrylate groups in a structurally confined environment. DA - 2011/1/13/ PY - 2011/1/13/ DO - 10.1021/jp107077t VL - 115 IS - 1 SP - 64-70 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp107077t DB - Crossref ER - TY - JOUR TI - Potential of P VA templated silica xerogels as adsorbents for Rhodamine 6G AU - Pirzada, T. AU - Shah, S.S. T2 - Journal of the Korean Chemical Society AB - PVA/silica hybrid xerogels were synthesized by sonohydrolysis of a mixture of 2-way catalyzed TEOS and water solution of PVA. PVA was successfully removed from the xerogels through calcination and its removal was confirmed through TGA analysis of the calcined gel. Microstructure of the gels was studied through SEM, XRD and FTIR. Nitrogen sorption studies were conducted to find out surface area of different samples. It was found out that the samples having PVA removed through calcinations have higher surface area (411.64 $m^2$/g) than the samples (353.544 $m^2$/g) synthesized without any PVA. Adsorption properties of these xerogels synthesized by using different ratios of components were studied by taking Rhodamine G6 as a model adsorbate. The experiments were conducted at room temperature ($25^{\circ}C$). UV visible spectroscopy was used to measure the concentration of the dye before and after adsorption. The adsorption data of Rhodamine G6 on PVA modified silica is described by the Freundlich's adsorption model. DA - 2011/// PY - 2011/// DO - 10.5012/jkcs.2011.55.6.1024 VL - 55 IS - 6 SP - 1024-1029 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84855440030&partnerID=MN8TOARS KW - PVA-silica hybrids KW - Sol-gel processing KW - Rhodamine 6 G KW - Adsorption KW - Sonohydrolysis ER - TY - JOUR TI - An Apparent Critical Point in Binary Mixtures of Nitrotoluene with Alkanes: Experimental and Simulation Study AU - Ratajczak, B. AU - Śliwinska-Bartkowiak, M. AU - Kozioł, T. AU - Coasne, B. AU - Gubbins, K.E. T2 - Journal of Computational Methods in Sciences and Engineering DA - 2011/// PY - 2011/// VL - 10 SP - 575–586 ER - TY - JOUR TI - Book Review: Engineering and Sustainable Community Development AU - Bullard, L.G. DA - 2011/// PY - 2011/// VL - 45 IS - 1 SP - 58 ER - TY - JOUR TI - Book Review: A New Agenda for Higher Education: Shaping a Life of the Mind for Practice AU - Bullard, L.G. T2 - Chemical Engineering Education DA - 2011/// PY - 2011/// VL - 45 IS - 4 ER - TY - ER - TY - BOOK TI - Stabilization of Thin Films, Foams, Emulsions and Bifluid Gels with Surface-Active Solid Particles AU - Velikov, K.P. AU - Velev, O.D. AB - This chapter contains sections titled: Introduction Absorption Behavior of Particles at Interfaces Mechanism of Stabilization of Foams and Emulsions by Spherical Particles Stabilization by Non-spherical Particles Multiple Emulsions Stabilized with Particles Bifluid Particle-stabilized Gels Conclusions and Outlook References DA - 2011/// PY - 2011/// DO - 10.1002/9783527631117.ch9 VL - 3 SE - 277-306 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84885967383&partnerID=MN8TOARS ER - TY - JOUR TI - Aqueous soft matter based photovoltaic devices AU - Koo, H.-J. AU - Chang, S.T. AU - Slocik, J.M. AU - Naik, R.R. AU - Velev, O.D. T2 - Journal of Materials Chemistry AB - We present a new type of photovoltaic systems based on aqueous soft gel materials. Two photosensitive ions, DAS− and [Ru(bpy)3]2+, were used as photoactive molecules embedded in aqueous gel. The hydrogel photovoltaic devices (HGPVs) showed performance comparable with or higher than those of other biomimetic or ionic photovoltaic systems reported recently. We suggest a provisional mechanism, which is based on a synergetic effect of the two dye molecules in photocurrent generation. We found an efficient replacement of the expensive Pt counter-electrode with copper coated with carbon materials, such as carbon nanotubes, carbon black or graphite. These Cu electrodes coated with carbon layers could drastically reduce the cost of such hydrogel devices without efficiency loss. Thus, a new class of low cost and flexible photovoltaic cells made of biocompatible matrix was demonstrated. Biologically derived photoactive molecules, such as Chlorophyll and Photosystem II, were successfully operated in aqueous gel media of such HGPVs. DA - 2011/// PY - 2011/// DO - 10.1039/c0jm01820a VL - 21 IS - 1 SP - 72-79 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-78649842869&partnerID=MN8TOARS ER - TY - JOUR TI - Temperature-controlled ‘breathing’ of carbon dioxide bubbles AU - Tumarkin, Ethan AU - Nie, Zhihong AU - Park, Jai Il AU - Abolhasani, Milad AU - Greener, Jesse AU - Sherwood-Lollar, Barbara AU - Günther, Axel AU - Kumacheva, Eugenia T2 - Lab on a Chip AB - We report a microfluidic (MF) approach to studies of temperature mediated carbon dioxide (CO2) transfer between the gas and the liquid phases. Micrometre-diameter CO2 bubbles with a narrow size distribution were generated in an aqueous or organic liquid and subsequently were subjected to temperature changes in the downstream channel. In response to the cooling-heating-cooling cycle the bubbles underwent corresponding contraction-expansion-contraction transitions, which we term ‘bubble breathing’. We examined temperature-controlled dissolution of CO2 in four exemplary liquid systems: deionized water, a 0.7 M aqueous solution of NaCl, ocean water extracted from Bermuda coastal waters, and dimethyl ether of poly(ethylene glycol), a solvent used in industry for absorption of CO2. The MF approach can be extended to studies of other gases with a distinct, temperature-dependent solubility in liquids. DA - 2011/// PY - 2011/// DO - 10.1039/c1lc20490d VL - 11 IS - 20 SP - 3545 ER - TY - JOUR TI - Toxicological studies on silver nanoparticles: challenges and opportunities in assessment, monitoring and imaging AU - Stensberg, M. C. AU - Wei, Q. S. AU - McLamore, E. S. AU - Porterfield, D. M. AU - Wei, A. AU - Sepulveda, M. S. T2 - Nanomedicine AB - Silver nanoparticles (Ag NPs) are becoming increasingly prevalent in consumer products as antibacterial agents. The increased use of Ag NP-enhanced products may lead to an increase in toxic levels of environmental silver, but regulatory control over the use or disposal of such products is lagging due to insufficient assessment on the toxicology of Ag NPs and their rate of release into the environment. In this article we discuss recent research on the transport, activity and fate of Ag NPs at the cellular and organismic level, in conjunction with traditional and recently established methods of nanoparticle characterization. We include several proposed mechanisms of cytotoxicity based on such studies, as well as new opportunities for investigating the uptake and fate of Ag NPs in living systems. DA - 2011/// PY - 2011/// DO - 10.2217/nnm.11.78 VL - 6 IS - 5 SP - 879-898 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000293335200014&KeyUID=WOS:000293335200014 KW - cell uptake KW - characterization methods KW - imaging KW - physiological sensing KW - silver nanoparticles KW - toxicology ER - TY - JOUR TI - Optical Imaging with Dynamic Contrast Agents AU - Wei, Q. S. AU - Wei, A. T2 - Chemistry-a European Journal AB - Abstract Biological imaging applications often employ molecular probes or nanoparticles for enhanced contrast. However, resolution and detection are still often limited by the intrinsic heterogeneity of the sample, which can produce high levels of background that obscure the signals of interest. Herein, we describe approaches to overcome this obstacle based on the concept of dynamic contrast: a strategy for elucidating signals by the suppression or removal of background noise. Dynamic contrast mechanisms can greatly reduce the loading requirement of contrast agents, and may be especially useful for single‐probe imaging. Dynamic contrast modalities are also platform‐independent, and can enhance the performance of sophisticated biomedical imaging systems or simple optical microscopes alike. Dynamic contrast is performed in two stages: 1) a signal modulation scheme to introduce time‐dependent changes in amplitude or phase, and 2) a demodulation step for signal recovery. Optical signals can be coupled with magnetic nanoparticles, photoswitchable probes, or plasmon‐resonant nanostructures for modulation by magnetomotive, photonic, or photothermal mechanisms, respectively. With respect to image demodulation, many of the strategies developed for signal processing in electronics and communication technologies can also be applied toward the editing of digital images. The image‐processing step can be as simple as differential imaging, or may involve multiple reference points for deconvolution by using cross‐correlation algorithms. Periodic signals are particularly amenable to image demodulation strategies based on Fourier transform; the contrast of the demodulated signal increases with acquisition time, and modulation frequencies in the kHz range are possible. Dynamic contrast is an emerging topic with considerable room for development, both with respect to molecular or nanoscale probes for signal modulation, and also to methods for more efficient image processing and editing. DA - 2011/// PY - 2011/// DO - 10.1002/chem.201002521 VL - 17 IS - 4 SP - 1080-1091 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000287562300001&KeyUID=WOS:000287562300001 KW - contrast agents KW - imaging techniques KW - magnetic properties KW - nanoparticles KW - photothermal reactions ER - TY - JOUR TI - Metal-Mesh Lithography AU - Tang, Z. AU - Wei, Q. S. AU - Wei, A. T2 - Acs Applied Materials & Interfaces AB - Metal-mesh lithography (MML) is a practical hybrid of microcontact printing and capillary force lithography that can be applied over millimeter-sized areas with a high level of uniformity. MML can be achieved by blotting various inks onto substrates through thin copper grids, relying on preferential wetting and capillary interactions between template and substrate for pattern replication. The resulting mesh patterns, which are inverted relative to those produced by stenciling or serigraphy, can be reproduced with low micrometer resolution. MML can be combined with other surface chemistry and lift-off methods to create functional microarrays for diverse applications, such as periodic islands of gold nanorods and patterned corrals for fibroblast cell cultures. DA - 2011/// PY - 2011/// DO - 10.1021/am201305x VL - 3 IS - 12 SP - 4812-4818 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000298341300038&KeyUID=WOS:000298341300038 KW - lithography KW - surface chemistry KW - microarrays KW - chemisorption KW - wetting ER - TY - JOUR TI - Gold Nanorods as Theranostic Agents AU - Wei, Alexander AU - Wei, Qingshan AU - Leonov, Alexei P. T2 - Nanoplatform-Based Molecular Imaging AB - This chapter contains sections titled: Introduction Physical Properties of GNRs Synthesis of GNRs Surface Chemistry of GNRs GNRs as Theranostic Agents Outlook Acknowledgments References DA - 2011/5// PY - 2011/5// DO - 10.1002/9780470767047.ch27 SP - 659-681 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84879348945&partnerID=MN8TOARS ER - TY - JOUR TI - Ionic Current Rectification in Soft-Matter Diodes with Liquid-Metal Electrodes AU - So, Ju-Hee AU - Koo, Hyung-Jun AU - Dickey, Michael D. AU - Velev, Orlin D. T2 - Advanced Functional Materials AB - Abstract A soft‐matter‐based diode composed of hydrogel and liquid metal (eutectic gallium indium, EGaIn) is presented. The ability to control the thickness, and thus resistivity, of an oxide skin on the metal enables rectification. First, a simple model system with liquid‐metal/electrolyte‐solution/Pt interfaces is characterized. The electrically insulating oxide skin on the EGaIn electrode is reduced or oxidized further depending on the direction of the bias, thereby allowing unidirectional ionic current. The forward current of the diode increases as the conductivity of the electrolyte increases, whereas backward current depends on the pH of the medium in contact with the insulating oxide layer on the EGaIn electrode. As a result, the diode shows a higher rectification ratio (defined as the ratio of forward to backward current measured at the same absolute bias) with more conductive electrolyte at neutral pH. Replacement of the liquid electrolyte solution with a hydrogel improves the structural stability of the soft diode. The rectification performance also improves due to the increased ionic conductivity by the gel. Finally, a diode composed entirely of soft materials by replacing the platinum electrode with a second liquid‐metal electrode is presented. Contacting each liquid metal with a polyelectrolyte gel featuring different pH values provided asymmetry in the device, which is necessary for rectification. A hydrogel layer infused with a strong basic polyelectrolyte removes the insulating oxide layer, allowing one interface with the EGaIn electrode to be conductive regardless of the direction of bias. Thus, the oxide layer at the other interface rectifies the current. DA - 2011/// PY - 2011/// DO - 10.1002/adfm.201101967 VL - 22 IS - 3 SP - 625-631 KW - hydrogels KW - liquid metal KW - ionic current rectification KW - polyelectrolytes KW - soft matter KW - soft electronics KW - electrochemical diodes ER - TY - JOUR TI - Superacidic electrospun fiber-nafion hybrid proton exchange membranes AU - Yao, Y. F. AU - Lin, Z. AU - Li, Y. AU - Alcoutlabi, M. AU - Hamouda, H. AU - Zhang, X. W. T2 - Advanced Energy Materials DA - 2011/// PY - 2011/// VL - 1 ER - TY - JOUR TI - Recent developments in nanostructured anode materials for rechargeable lithium-ion batteries AU - Ji, L. W. AU - Lin, Z. AU - Alcoutlabi, M. AU - Zhang, X. W. T2 - Energy & Environmental Science DA - 2011/// PY - 2011/// VL - 4 ER - TY - JOUR TI - Lithium-oxygen batteries-Limiting factors that affect performance AU - Padbury, R. AU - Zhang, X. W. T2 - Journal of Power Sources DA - 2011/// PY - 2011/// VL - 196 ER - TY - JOUR TI - Electrospun Nanofibers for Energy Storage AU - Alcoutlabi, Mataz AU - Ji, Liwen AU - Guo, Bingkun AU - Li, Shuli AU - Li, Ying AU - Zhang, Shu AU - Toprakci, Ozan AU - Zhang, Xiangwu T2 - Aatcc Review DA - 2011/// PY - 2011/// VL - 11 IS - 6 SP - 45-51 ER - TY - JOUR TI - Electrospun Li4Ti5O12/C composites for lithium-ion batteries with high rate performance AU - Guo, Bingkun AU - Li, Ying AU - Yao, Yingfang AU - Lin, Zhan AU - Ji, Liwen AU - Xu, Guangjie AU - Liang, Yinzheng AU - Shi, Quan AU - Zhang, Xiangwu T2 - Solid State Ionics AB - Mixed-conducting lithium-ion doped emeraldine polyaniline (PAni)–polyethylene oxide (PEO) blends have been developed to achieve an optimal electronic–ionic conductivity balance in nano-tin composite anodes. Electrochemical evaluation was performed on the anodes with differing electrode preparation procedures, doping methods and PEO contents. Results indicate that both good electronic and ionic conductivity in the binder are required for rapid lithium insertion/extraction and low polarization. This doped PAni–PEO polymer blend is an attractive binder for high capacity composite anodes with low polarization. DA - 2011/// PY - 2011/// DO - 10.1016/S0167-2738(02)00522-2 VL - 204 IS - 3-4 SP - 61-65 KW - nano-tin KW - polyaniline KW - polyethylene oxide KW - polymer blend KW - composite electrode KW - mixed conductivity ER - TY - JOUR TI - Electrode Catalyst Materials in Direct Methanol Fuel Cells AU - Lin, Zhan AU - Zhang, Xiangwu T2 - International Journal of Nano Science, Nano Engineering and Nanotechnology DA - 2011/// PY - 2011/// VL - 3 SP - 1-24 ER - TY - JOUR TI - A Facile Approach to Fabricate Porous Nylon 6 Nanofibers Using Silica Nanotemplate AU - Shi, Quan AU - Vitchuli, Narendiran AU - Ji, Liwen AU - Nowak, Joshua AU - McCord, Marian AU - Bourham, Mohamed AU - Zhang, Xiangwu T2 - Journal of Applied Polymer Science AB - Abstract Porous Nylon 6 nanofibers were prepared using silica nanoparticles as the template. Firstly, Nylon 6/silica composite nanofibers were prepared as precursors by electrospinning Nylon 6 solutions containing different contents of silica nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the surface morphology and the inner structure of composite nanofibers; where it was found that silica nanoparticles were distributed both inside and on the surface of nanofibers. Analytical techniques [Fourier transform infrared (FTIR), differential scanning calorimetry, thermal gravimetric analysis (TGA), and wide‐angle X‐ray diffraction) were used to study the structure and properties of these composite nanofibers. The glass transition, melting, and crystallization processes of the fibers were affected by the addition of silica nanoparticles. Secondly, porous Nylon 6 nanofibers were obtained by removing silica nanoparticles via hydrofluoric acid treatment. The removal of silica nanoparticles was confirmed using FTIR and TGA tests. SEM and TEM observations revealed the formation of the porous structure in these nanofibers. After the formation of the porous structure, Brunauer–Emmett–Teller specific surface areas of nanofibers were increased as compared to solid Nylon 6 and composite nanofibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 DA - 2011/// PY - 2011/// DO - 10.1002/app.33161 VL - 120 IS - 1 SP - 425-433 UR - https://publons.com/publon/3117881/ KW - electrospinning KW - nanocomposite KW - porous nanofibers KW - Nylon 6 ER - TY - CONF TI - Zinc Oxide/Nylon 6 Electrospun Fibers for Warfare Protective Applications C2 - 2011/4// C3 - 2011 AATCC Materials Research Poster Competition DA - 2011/4// ER - TY - CONF TI - Zinc Oxide/Nylon 6 Electrospun Fibers for Warfare Protective Applications C2 - 2011/4// C3 - 2nd Engineering Day at the NC Legislature DA - 2011/4// ER - TY - CONF TI - Si/C Nanofiber Composite Anodes for New-Generation Rechargeable Lithium-Ion Batteries C2 - 2011/4// C3 - the Sixth Annual NC State University Graduate Student Research Symposium DA - 2011/4// ER - TY - CONF TI - Si/C Nanofiber Composite Anodes for New-Generation Rechargeable Lithium-Ion Batteries C2 - 2011/11// C3 - 2011 MRS Fall Meeting & Exhibit DA - 2011/11// ER - TY - CONF TI - Novel Atmospheric Plasma Enhanced Composite Wound Dressings C2 - 2011/10// C3 - NTC Forum DA - 2011/10// ER - TY - CONF TI - Novel Atmospheric Plasma Enhanced Chitosan Nanofiber/Gauze Composite Wound Dressings C2 - 2011/4// C3 - 2011 AATCC Materials Research Poster Competition DA - 2011/4// ER - TY - CONF TI - New Li2MnSiO4/C Nanocomposite Cathode Materials C2 - 2011/11// C3 - 2011 MRS Fall Meeting & Exhibit DA - 2011/11// ER - TY - CONF TI - MnOx/Carbon Composite Nanofiber Cathodes for Rechargeable Li/Air Batteries C2 - 2011/11// C3 - 2011 MRS Fall Meeting & Exhibit DA - 2011/11// ER - TY - CONF TI - Fabrication and Electrochemical Characteristics of Electrospun LiFePO4/Carbon+Graphene Composite Nanofibers for Lithium-Ion Batteries C2 - 2011/11// C3 - 2011 MRS Fall Meeting & Exhibit DA - 2011/11// ER - TY - CONF TI - Electrospun Composite Nanofibers for Lithium-Ion Batteries C2 - 2011/10// C3 - NTC Forum DA - 2011/10// ER - TY - CONF TI - Carbon Nanofiber/Manganese Oxide Composites as the Cathode for Li-air Batteries C2 - 2011/8// C3 - NC State Undergraduate Research Summer Symposium DA - 2011/8// ER - TY - CONF TI - Carbon Nanofiber/Manganese Oxide Composites as the Cathode for Li-air Batteries C2 - 2011/9// C3 - NC State Undergraduate Research Summer Symposium DA - 2011/9// ER - TY - JOUR TI - Binding affinity of a small molecule to an amorphous polymer in a solvent. Part 2: Preferential binding to local sites on a surface AU - Chunsrivirot, S. AU - Santiso, Erik E. AU - Trout, B.L. T2 - Langmuir AB - Crystallization, a separation and purification process, is commonly used to produce a wide range of materials in various industries, and it usually begins with heterogeneous nucleation on a foreign surface in industrial practice and most other circumstances. Recent studies show that amorphous polymeric substrates are useful in controlling crystallization and selectively producing pharmaceutical polymorphs. In our previous publication, we investigated the possible correlation of the binding affinity of one molecule to key binding sites (local binding), and the possibility of using this binding affinity to guide the selection of polymers promoting heterogeneous nucleation. The studied systems were aspirin binding to four nonporous cross-linked polymers in ethanol-water 38 v% mixture. Cross-linked with divinylbenzene (DVB), these polymers were poly(4-acryloylmorpholine) (PAM), poly(2-carboxyethyl acrylate) (PCEA), poly(4-hydroxylbutyl acrylate) (PHBA), and polystyrene (PS). We discovered that the trend of the magnitudes of the average free energies of binding to the best sites is very similar to that of heterogeneous nucleation activities. This Article aims to investigate whether or not local binding to key sites is the important variable to describe heterogeneous nucleation as opposed to the overall/average binding affinity of molecules to a surface, and to investigate the possibility of using the overall binding affinity to guide the selection of polymers. We used the polymer surfaces generated from our previous study to calculate the overall binding affinity of aspirin molecules to the surface as measured by the preferential interaction coefficients of aspirin (1 m) to these polymers. We discovered that the trend of the average preferential interaction coefficients does not correlate as well to that of heterogeneous nucleation activities as the free energies of binding to the best sites. We also computed the average numbers of aspirin molecules associated with the areas of the surfaces' best binding sites and found that they correlate better to heterogeneous nucleation activities than the average preferential interaction coefficients. These results further support that local binding is indicative of heterogeneous nucleation. Moreover, we found a weak trend of the distance order parameters of the aspirin molecules to be similar that of heterogeneous nucleation activities. Our results from the two-part study suggest the importance of local binding to heterogeneous nucleation as well as the possibility of using the binding affinity to the local area (the free energy of binding to the best site and the number of nucleating molecules associated with the area of the best binding site) and the distance order parameters to guide the selection of polymers. DA - 2011/// PY - 2011/// DO - 10.1021/la202593u VL - 27 IS - 20 SP - 12396–12404 ER - TY - CONF TI - Choosing the road less traveled: Ten years later AU - Bullard, L. G. AU - Knoll, P. AU - Saterback, A. C2 - 2011/// C3 - ASEE Annual Conference Proceedings DA - 2011/// SP - 324-349 ER - TY - JOUR TI - Identification of Tetrahydrofuran Reaction Pathways in Premixed Flames AU - Kasper, Tina AU - Lucassen, Arnas AU - Jasper, Ahren W. AU - Li, Wenjun AU - Westmoreland, Phillip AU - Kohse-Höinghaus, Katharina AU - Yang, Bin AU - Wang, Juan AU - Cool, Terrill A. AU - Hansen, Nils AU - al. T2 - Zeitschrift für Physikalische Chemie AB - Abstract Premixed low-pressure tetrahydrofuran/oxygen/argon flames are investigated by photoionization molecular-beam mass spectrometry using vacuum-ultraviolet synchrotron radiation. For two equivalence ratios ( φ = 1.00 and 1.75), mole fractions are measured as a function of distance from the burner for almost 60 intermediates with molar masses ranging from 2 (H 2 ) to 88 (C 4 H 6 O 2 ), providing a broad database for flame modeling studies. The isomeric composition is resolved by comparisons between experimental photoionization efficiency data and theoretical simulations, based on calculated ionization energies and Franck - Condon factors. Special emphasis is put on the resolution of the first reaction steps in the fuel destruction. The photoionization experiments are complemented by electron-ionization molecular-beam mass-spectrometry measurements that provide data with high mass resolution. For three additional flames with intermediate equivalence ratios ( φ = 1.20 , 1.40 and 1.60), mole fractions of major species and photoionization efficiency spectra of intermediate species are reported, extending the database for the development of chemical kinetic models. DA - 2011/12// PY - 2011/12// DO - 10.1524/zpch.2011.0163 VL - 225 IS - 11-12 SP - 1237-1270 J2 - Zeitschrift für Physikalische Chemie LA - en OP - SN - 0942-9352 UR - http://dx.doi.org/10.1524/zpch.2011.0163 DB - Crossref KW - Combustion Chemistry KW - Laminar Flames KW - Molecular Beam Mass Spectrometry KW - Tetrahydrofuran KW - Biofuel ER - TY - BOOK TI - Green Chemistry and Engineering: A Practical Design Approach AU - Jimenez-Gonzalez, Concepcion AU - Constable, David DA - 2011/// PY - 2011/// PB - Hoboken, N.J.: Wiley, SN - 9780470170878 ER - TY - JOUR TI - Electrospun Nanofiber-Based Anodes, Cathodes, and Separators for Advanced Lithium-Ion Batteries AU - Zhang, Xiangwu AU - Ji, Liwen AU - Toprakci, Ozan AU - Liang, Yinzheng AU - Alcoutlabi, Mataz T2 - POLYMER REVIEWS AB - Novel nanofiber technologies present the opportunity to design new materials for advanced rechargeable lithium-ion batteries. Among the various existing energy storage technologies, rechargeable lithium-ion batteries are considered as effective solution to the increasing need for high-energy electrochemical power sources. This review addresses using electrospinning technology to develop novel composite nanofibers which can be used as anodes, cathodes, and separators for lithium-ion batteries. The discussion focuses on the preparation, structure, and performance of silicon/carbon (Si/C) nanofiber anodes, lithium iron phosphate/carbon (LiFePO4/C) nanofiber cathodes, and lithium lanthanum titanate oxide/polyacrylonitrile (LLTO/PAN) nanofiber separators. Si/C nanofiber anodes have the advantages of both carbon (long cycle life) and Si (high lithium-storage capacity). LiFePO4/C nanofiber cathodes show good electrochemical performance including satisfactory capacity and good cycling stability. LLTO/PAN nanofiber separators have large electrolyte uptake, high ionic conductivity, and low interfacial resistance with lithium, which increase the capacity and improve the cycling stability of lithium-ion cells. These results demonstrate that electrospinning is a promising approach to prepare high-performance nanofiber anodes, nanofiber cathodes, and nanofiber separators that can potentially replace currently-used lithium-ion battery materials. DA - 2011/// PY - 2011/// DO - 10.1080/15583724.2011.593390 VL - 51 IS - 3 SP - 239-264 SN - 1558-3716 UR - https://publons.com/publon/674396/ ER - TY - CHAP TI - Electrolytes for lithium ion battery materials AU - Lex-Balducci, A. AU - Henderson W., AU - Passerini, S. T2 - Lithium-Ion Batteries: Advanced Materials and Technologies A2 - Yuan, Y. A2 - Liu, H. A2 - Zhang, J. PY - 2011/// SP - 147-184 PB - Boca Raton, FL : CRC Press, SN - 9781439841280 ER - TY - JOUR TI - Deviation from time-composition equivalence in polymer solutions with selective cosolvents AU - Krishnan, Arjun S. AU - Spontak, Richard J. T2 - AIP ADVANCES AB - Time-composition superpositioning (tCS) permits determination of the mechanical properties of polymeric materials over a widely extended time (or frequency) domain by systematically varying composition under isothermal conditions. We have recently reported (Soft Matter, 6, 4331, 2010) the existence of such equivalence in technologically relevant triblock copolymers swollen with miscible, midblock-selective cosolvents differing in chemical constitution and viscosity. In this study, chemically homologous homopolymer and copolymer systems exhibiting rheological properties that deviate from tCS are investigated. With regard to the particular case of selectively solvated triblock copolymers, the source of deviation is explained in the context of endblock hopping. DA - 2011/12// PY - 2011/12// DO - 10.1063/1.3666980 VL - 1 IS - 4 SP - SN - 2158-3226 ER - TY - JOUR TI - Assessing the effect of molecular weight on the kinetics of backbone scission reactions in polyethylene using Reactive Molecular Dynamics AU - Smith, K.D. AU - Bruns, M. AU - Stoliarov, S.I. AU - Nyden, M.R. AU - Ezekoye, O.A. AU - Westmoreland, P.R. T2 - Polymer AB - Kinetics of polymer bond scission, the initial step in thermal decomposition of polyethylene and other vinyl polymers, was investigated as a function of the number of repeat units using an improved Reactive Molecular Dynamics (RMD) approach, which is introduced here. The rate of scission per bond is shown to depend on the degree of polymerization, an effect not captured by the conventional practice of modeling polymer decomposition with small-molecule Arrhenius parameters. In the new approach, implemented in an open-source C++ code RxnMD, well-behaved reactive force fields are generated using switching functions that activate and attenuate terms obtained from a conventional, non-reactive force field. In this way, predefined reaction types are modeled accurately by interpolating smoothly between non-reactive potential energy terms describing reactants, transition states, and products. DA - 2011/6// PY - 2011/6// DO - 10.1016/j.polymer.2011.04.035 VL - 52 IS - 14 SP - 3104-3111 J2 - Polymer LA - en OP - SN - 0032-3861 UR - http://dx.doi.org/10.1016/j.polymer.2011.04.035 DB - Crossref KW - Reactive molecular dynamics KW - Polyethylene KW - Backbone scission ER - TY - JOUR TI - Role of Signaling Pathways and Epigenetic Factors in Lineage Determination During Human Embryonic Stem Cell Differentiation AU - Sarkar, P. AU - Rao, B.M T2 - Embryonic Stem Cells - Differentiation and Pluripotent Alternatives DA - 2011/// PY - 2011/// VL - 1 SP - 1 ER - TY - JOUR TI - Progress and future directions for atomic layer deposition and ALD-based chemistry AU - Parsons, Gregory N. AU - George, Steven M. AU - Knez, Mato T2 - MRS BULLETIN AB - Abstract DA - 2011/11// PY - 2011/11// DO - 10.1557/mrs.2011.238 VL - 36 IS - 11 SP - 865-871 SN - 1938-1425 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000299230300015&KeyUID=WOS:000299230300015 ER - TY - JOUR TI - Phase Behavior of Ionic Liquid-LiX Mixtures: Pyrrolidinium Cations and TFSI- Anions - Linking Structure to Transport Properties AU - Zhou, Qian AU - Boyle, Paul D. AU - Malpezzi, Luciana AU - Mele, Andrea AU - Shin, Joon-Ho AU - Passerini, Stefano AU - Henderson, Wesley A. T2 - CHEMISTRY OF MATERIALS AB - The thermal phase behavior and ionic conductivity of mixtures of N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquids (PY1RTFSI where R = 4 or 5 for butyl or pentyl) with LiTFSI have been examined as model systems for ionic liquid-based lithium battery electrolytes. Several mixed salt crystalline phases form. The ionic conductivity variability of the mixtures correlates well with the reported phase behavior. The crystal structures for the (1-x) PY1RTFSI-(x) LiTFSI (x = 0.67) (or 1/2 PY1RTFSI/LiTFSI with R = 4 or 5) phases have been determined. These phases are isostructural, consisting of ionic planar layers formed by Li+···TFSI– linkages in which the uncoordinated PY1R+ cations reside in cavities within the layers. These structures have been used to aid in correlating Raman data with cation–anion coordination in the IL-LiTFSI binary salt mixtures. DA - 2011/10/11/ PY - 2011/10/11/ DO - 10.1021/cm201427k VL - 23 IS - 19 SP - 4331-4337 SN - 0897-4756 KW - ionic liquid KW - battery electrolyte KW - lithium KW - LiTFSI KW - phase behavior ER - TY - JOUR TI - Role of metal oxide support in redox reactions of iron oxide for chemical looping applications: experiments and density functional theory calculations AU - Li, Fanxing AU - Luo, Siwei AU - Sun, Zhenchao AU - Bao, Xiaoguang AU - Fan, Liang-Shih T2 - ENERGY & ENVIRONMENTAL SCIENCE AB - Aided by an oxygen carrier such as iron oxide, the chemical looping process can convert carbonaceous fuels while effectively capturing CO2. Previous experimental studies indicate that adding TiO2 support to iron oxide can notably improve the reactivity of iron oxide over multiple redox cycles, making it more suitable for chemical looping applications. In this study, wüstite (Fe1−xO) was used to represent pure iron(II) oxide and ilmenite (FeTiO3) was used to represent TiO2 supported iron(II) oxide. The underlying mechanisms for the improved iron oxide performance with TiO2 support are investigated through experiments and periodic Density Functional Theory (DFT) calculations. Both experimental and DFT studies indicate that TiO2 support is unlikely to reduce the activation energy for the reduction of iron(II) oxide. The support, however, can significantly lower the energy barrier for O2− migration within the dense solid phase, thereby enhancing the O2− diffusivity. The good agreements between experiments and DFT calculations confirm that the improved reactivity and recyclability of TiO2 supported iron oxide particles are likely to result from the significantly enhanced O2− diffusivity with the presence of support. DA - 2011/9// PY - 2011/9// DO - 10.1039/c1ee01325d VL - 4 IS - 9 SP - 3661-3667 SN - 1754-5706 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80052249355&partnerID=MN8TOARS ER - TY - JOUR TI - Phase-specific pore growth in ultrathin bicomponent films from cellulose-based polysaccharides AU - Taajamaa, Laura AU - Rojas, Orlando J. AU - Laine, Janne AU - Kontturi, Eero T2 - SOFT MATTER AB - The preparation of ultrathin (<100 nm) bicomponent films from hydrophobic polysaccharides with phase-specific pore growth was demonstrated and the underlying phenomena behind morphology formation were fundamentally investigated. The films were constructed, in a single-step process, by spin coating mixtures of trimethylsilyl cellulose (TMSC) and cellulose triacetate (CTA) from a common solvent. Atomic force microscopy (AFM) revealed a nano- and micron-scale phase separated structure, typical for interfacial polymer blends. Vertical phase separation had resulted in a continuous layer of TMSC next to the substrate with laterally phase separated CTA and TMSC on top. Furthermore, X-ray photoelectron spectroscopy (XPS) and contact angle measurements indicated the presence of a thin overlayer of TMSC. In addition, increased relative humidity conditions during spin coating resulted in the formation of pores when the CTA weight percent in the blend was in the range from 17 to 83% (i.e., in TMSC/CTA blend ratios 5 : 1, 2 : 1, 1 : 2, and 1 : 5). Closer analysis of the morphology indicated that the pores resided exclusively in the CTA phase. Hypothetically, the formation of the observed peculiar morphologies was ascribed to various phenomena occurring upon spin coating: vertical and lateral polymer phase separation, dewetting under humid atmosphere, and layer inversion during dewetting. It is concluded that the obtained ultrathin polysaccharide films with tailored surface pores, morphology and wettability are expected to be useful in emerging nanotechnologies while having the advantage of an effortless manufacturing process. DA - 2011/// PY - 2011/// DO - 10.1039/c1sm06020a VL - 7 IS - 21 SP - 10386-10394 SN - 1744-6848 ER - TY - JOUR TI - Orientational prewetting of planar solid substrates by a model liquid crystal AU - Greschek, Manuel AU - Schoen, Martin T2 - JOURNAL OF CHEMICAL PHYSICS AB - We present grand canonical ensemble Monte Carlo simulations of prewetting transitions in a model liquid crystal at structureless solid substrates. Molecules of the liquid crystal interact via anisometric Lennard-Jones potentials and can be anchored planar or homeotropically at the substrates. Fluid-substrate attraction is modeled by a Yukawa potential of variable range. By monitoring the grand-potential density and the nematic order parameter as functions of the chemical potential μ, several discontinuous prewetting, wetting, and isotropic-nematic phase transitions are observed. These transitions depend on both the range of the fluid-substrate attraction and the specific anchoring at the substrate. Our results show that at substrates characterized by degenerate anchoring prewetting occurs at lower μ compared with cases in which the anchoring is monostable. This indicates that prewetting transitions are driven by orientational entropy because degenerate anchoring allows for more orientationally distinct configurations of molecules compared with monostable anchoring. In addition, by analyzing local density and various local order parameters, a detailed picture of the structure of various phases emerges from our simulations. DA - 2011/11/28/ PY - 2011/11/28/ DO - 10.1063/1.3660377 VL - 135 IS - 20 SP - SN - 0021-9606 ER - TY - JOUR TI - Multifunctional ZnO/Nylon 6 nanofiber mats by an electrospinning-electrospraying hybrid process for use in protective applications AU - Vitchuli, Narendiran AU - Shi, Quan AU - Nowak, Joshua AU - Kay, Kathryn AU - Caldwell, Jane M. AU - Breidt, Frederick AU - Bourham, Mohamed AU - McCord, Marian AU - Zhang, Xiangwu T2 - SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS AB - ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process in which ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers without becoming completely embedded. The prepared ZnO/Nylon 6 nanofiber mats were evaluated for their abilities to kill bacteria or inhibit their growth and to catalytically detoxify chemicals. Results showed that these ZnO/Nylon 6 nanofiber mats had excellent antibacterial efficiency (99.99%) against both the Gram-negative Escherichia coli and Gram-positive Bacillus cereus bacteria. In addition, they exhibited good detoxifying efficiency (95%) against paraoxon, a simulant of highly toxic chemicals. ZnO/Nylon 6 nanofiber mats were also deposited onto nylon/cotton woven fabrics and the nanofiber mats did not significantly affect the moisture vapor transmission rates and air permeability values of the fabrics. Therefore, ZnO/Nylon 6 nanofiber mats prepared by the electrospinning-electrospraying hybrid process are promising material candidates for protective applications. DA - 2011/10// PY - 2011/10// DO - 10.1088/1468-6996/12/5/055004 VL - 12 IS - 5 SP - SN - 1468-6996 UR - https://publons.com/publon/3117882/ KW - electrospinning KW - electrospraying KW - Nylon 6 KW - zinc oxide KW - antibacterial KW - detoxification ER - TY - JOUR TI - Ionic diffusion in the oxidation of iron-effect of support and its implications to chemical looping applications AU - Li, Fanxing AU - Sun, Zhenchao AU - Luo, Siwei AU - Fan, Liang-Shih T2 - ENERGY & ENVIRONMENTAL SCIENCE AB - Addition of TiO2 was found to significantly enhance the ionic diffusivity of O anion within iron and its oxides, thereby changing the dominating ionic transfer mechanism for iron oxidation from “outward Fe cation diffusion” (in pure Fe case) to “inward O anion diffusion” (in Fe with TiO2 support case). DA - 2011/3// PY - 2011/3// DO - 10.1039/c0ee00589d VL - 4 IS - 3 SP - 876-880 SN - 1754-5706 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79952435405&partnerID=MN8TOARS ER - TY - JOUR TI - Experimental Study of HCl Capture Using CaO Sorbents: Activation, Deactivation, Reactivation, and Ionic Transfer Mechanism AU - Sun, Zhenchao AU - Yu, Fu-Chen AU - Li, Fanxing AU - Li, Songgeng AU - Fan, Liang-Shih T2 - INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH AB - Experimental study of dry HCl removal from synthesis gas or flue gas using CaO sorbents, in the context of CaO-based chemical looping processes, is reported. The study was first conducted in a TGA and a fixed-bed reactor to test the effects of chloridation temperature, sorbent particle size, HCl concentration, and space velocity on the HCl capture capacity. The chloridation reactivity deterioration of CaO sorbents with multicyclic carbonation−calcination reaction (CCR) and/or at high calcination temperatures, which are of notable relevance to the CaO-based chemical looping processes, was also investigated. In addition, precipitation (activation) and hydration (reactivation) were used to enhance initial sorbent reactivity and to reactivate the deactivated sorbents, respectively. The effects of deactivation, activation, and reactivation were explained by the morphological property change of the sorbents. To further elucidate the solid phase reaction mechanism of CaO and HCl, ionic transfer behavior during chloridation reaction was characterized using an inert marker experiment. Through the present work, the performance of CaO sorbents in HCl capture, deactivation of the sorbents by high-temperature calcination and multiple CCR cycles, sorbent activation and reactivation strategies, and the corresponding reaction mechanisms are determined. DA - 2011/5/18/ PY - 2011/5/18/ DO - 10.1021/ie102587s VL - 50 IS - 10 SP - 6034-6043 SN - 0888-5885 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79955917323&partnerID=MN8TOARS ER - TY - JOUR TI - Electrospun Li4Ti5O12/C composites for lithium-ion batteries with high rate performance AU - Guo, Bingkun AU - Li, Ying AU - Yao, Yingfang AU - Lin, Zhan AU - Ji, Liwen AU - Xu, Guangjie AU - Liang, Yinzheng AU - Shi, Quan AU - Zhang, Xiangwu T2 - SOLID STATE IONICS AB - Two types of Li4Ti5O12/C composites were synthesized through the electrospinning method. The first composite consists of Li4Ti5O12 nanoparticles and aggregates coated by carbon and connected by carbon nanofibers. The second composite is constructed solely by Li4Ti5O12/C fibers. These two composites are denoted as Li4Ti5O12/C particles/fibers and Li4Ti5O12/C fibers, respectively. It is found that both composites show higher reversible capacities and better rate performance than commercial Li4Ti5O12 nanoparticles. Comparing the two electrospun composites, Li4Ti5O12/C fibers exhibit higher reversible capacity, greater rate capacity, and smaller electrode polarization, indicating that Li4Ti5O12/C fibers have better kinetics than Li4Ti5O12/C particles/fibers due to the elimination of Li4Ti5O12 aggregates and the formation of carbon-based fiber structure. DA - 2011/12/12/ PY - 2011/12/12/ DO - 10.1016/j.ssi.2011.10.019 VL - 204 SP - 61-65 SN - 1872-7689 UR - https://publons.com/publon/3117890/ KW - Lithium-ion batteries KW - Anodes KW - Li4Ti5O12 KW - Nanofibers KW - Nanoparticles ER - TY - JOUR TI - Design of small molecule-responsive microRNAs based on structural requirements for Drosha processing AU - Beisel CL, Chen AU - YY, Culler SJ AU - Hoff KG, AU - CD, Smolke T2 - Nucleic Acids Research DA - 2011/// PY - 2011/// VL - 39 IS - 7 SP - 2981-2994 ER - TY - JOUR TI - The base pairing RNA Spot 42 participates in a multi-output feedforward loop to help enact catabolite repression in Escherichia coli AU - CL, Beisel AU - G, Storz T2 - Molecular Cell DA - 2011/// PY - 2011/// VL - 41 SP - 1-12 ER - TY - JOUR TI - Superacidic Electrospun Fiber-Nafion Hybrid Proton Exchange Membranes AU - Yao, Yingfang AU - Lin, Zhan AU - Li, Ying AU - Alcoutlabi, Mataz AU - Hamouda, Hechmi AU - Zhang, Xiangwu T2 - ADVANCED ENERGY MATERIALS AB - Abstract A novel type of hybrid membrane has been fabricated by incorporating superacidic sulfated zirconia (S‐ZrO 2 ) fibers into recast Nafion for proton exchange membrane fuel cells (PEMFCs). With the introduction of electrospun superacidic fiber mats, a large amount of protogenic groups aggregated in the interfacial region between S‐ZrO 2 fibers and the ionomer matrix, forming continuous pathways for facile proton transport. The resultant hybrid membranes had high proton conductivities, which were controlled by selectively adjusting the fiber diameter and fiber volume fraction. Consequently, the superacidic S‐ZrO 2 electrospun fibers are promising filler materials and hybrid membranes containing S‐ZrO 2 fiber mats can be potentially used in high‐performance fuel cells. DA - 2011/11// PY - 2011/11// DO - 10.1002/aenm.201100435 VL - 1 IS - 6 SP - 1133-1140 SN - 1614-6840 UR - https://publons.com/publon/6540073/ KW - hybrid membranes KW - fuel cells KW - Nafion KW - superacidic solids KW - fibers ER - TY - JOUR TI - Spontaneous Formation of Twisted A beta(16-22) Fibrils in Large-Scale Molecular-Dynamics Simulations AU - Cheon, Mookyung AU - Chang, Iksoo AU - Hall, Carol K. T2 - BIOPHYSICAL JOURNAL AB - Protein aggregation is associated with fatal neurodegenerative diseases, including Alzheimer's and Parkinson's. Mapping out kinetics along the aggregation pathway could provide valuable insights into the mechanisms that drive oligomerization and fibrillization, but that is beyond the current scope of computational research. Here we trace out the full kinetics of the spontaneous formation of fibrils by 48 Aβ(16-22) peptides, following the trajectories in molecular detail from an initial random configuration to a final configuration of twisted protofilaments with cross-β-structure. We accomplish this by performing large-scale molecular-dynamics simulations based on an implicit-solvent, intermediate-resolution protein model, PRIME20. Structural details such as the intersheet distance, perfectly antiparallel β-strands, and interdigitating side chains analogous to a steric zipper interface are explained by and in agreement with experiment. Two characteristic fibrillization mechanisms - nucleation/templated growth and oligomeric merging/structural rearrangement - emerge depending on the temperature. DA - 2011/11/16/ PY - 2011/11/16/ DO - 10.1016/j.bpj.2011.08.042 VL - 101 IS - 10 SP - 2493-2501 SN - 0006-3495 ER - TY - JOUR TI - Simultaneous Bulk- and Surface-Initiated Controlled Radical Polymerization from Planar Substrates AU - Turgman-Cohen, Salomon AU - Genzer, Jan T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY AB - We employ Monte Carlo computer simulations to investigate the simultaneous controlled radical polymerization in solution and from a flat surface. The bulk polymers grow at faster rates and possess narrower molecular weight distribution than polymers initiated from flat, impenetrable surfaces. The rate of surface-initiated polymerization depends on the density of initiator sites. Our results provide evidence that the assumption that the molecular weight of surface-initiated polymers is equal to that of polymers grown in bulk, invoked often in determining the grafting density of surface-bound polymers, is generally invalid. DA - 2011/11/9/ PY - 2011/11/9/ DO - 10.1021/ja2081636 VL - 133 IS - 44 SP - 17567-17569 SN - 0002-7863 ER - TY - JOUR TI - Mammalian Cell Viability in Electrospun Composite Nanofiber Structures AU - Canbolat, Mehmet Fatih AU - Tang, Christina AU - Bernacki, Susan H. AU - Pourdeyhimi, Behnam AU - Khan, Saad T2 - MACROMOLECULAR BIOSCIENCE AB - Incorporation of mammalian cells into nanofibers (cell electrospinning) and multilayered cell-nanofiber structures (cell layering) via electrospinning are promising techniques for tissue engineering applications. We investigate the viability of 3T3-L1 mouse fibroblasts after incorporation into poly(vinyl alcohol) nanofibers and multilayering with poly(caprolactone) nanofibers and analyze the possible factors that affect cell viability. We observe that cells do not survive cell electrospinning but survive cell layering. Assessing the factors involved in cell electrospinning, we find that dehydration and fiber stretching are the main causes of cell death. In cell layering, the choice of solvent is critical, as residual solvent in the electrospun fibers could be detrimental to the cells. DA - 2011/10/10/ PY - 2011/10/10/ DO - 10.1002/mabi.201100108 VL - 11 IS - 10 SP - 1346-1356 SN - 1616-5195 KW - 3T3-L1 mice fibroblasts KW - electrospinning KW - nanofibers KW - fibers KW - nanotechnology KW - tissue engineering KW - viability ER - TY - JOUR TI - Highly active photocatalytic ZnO nanocrystalline rods supported on polymer fiber mats: Synthesis using atomic layer deposition and hydrothermal crystal growth AU - Gong, Bo AU - Peng, Qing AU - Na, Jeong-Seok AU - Parsons, Gregory N. T2 - APPLIED CATALYSIS A-GENERAL AB - Photocatalytically active zinc oxide nanocrystalline rods are grown on high surface area polybutylene terephthalate (PBT) polymer fiber mats using low temperature solution based methods, where the oxide crystal nucleation is facilitated using conformal thin films formed by low temperature vapor phase atomic layer deposition (ALD). Scanning electron microscopy (SEM) confirms that highly oriented single crystal ZnO nanorod crystals are directed normal to the starting fiber substrate surface, and the extent of nanocrystal growth within the fiber mat bulk is affected by the overall thickness of the ZnO nucleation layer. The high surface area of the nanocrystal-coated fibers is confirmed by nitrogen adsorption/desorption analysis. An organic dye in aqueous solution in contact with the coated fiber degraded rapidly upon ultraviolet light exposure, allowing quantitative analysis of the photocatalytic properties of fibers with and without nanorod crystals present. The dye degrades nearly twice as fast in contact with the ZnO nanorod crystals compared with samples with only an ALD ZnO layer. Additionally, the catalyst on the polymer fiber mat could be reused without need for a particle recovery step. This combination of ALD and hydrothermal processes could produce high surface area finishes on complex polymer substrates for reusable photocatalytic and other surface-reaction applications. DA - 2011/11/4/ PY - 2011/11/4/ DO - 10.1016/j.apcata.2011.08.041 VL - 407 IS - 1-2 SP - 211-216 SN - 0926-860X UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000297234400025&KeyUID=WOS:000297234400025 KW - Atomic layer deposition KW - Nonwoven fiber KW - Diethyl zinc KW - Zinc oxide KW - Nanocrystals KW - Nanorods KW - Hydrothermal KW - Photocatalytic ER - TY - JOUR TI - Electrospun nanofibers for energy storage AU - Alcoutlabi, M. AU - Ji, L. W. AU - Guo, B. K. AU - Li, S. L. AU - Li, Y. AU - Zhang, S. AU - Toprakci, O. AU - Zhang, X. W. T2 - AATCC Review DA - 2011/// PY - 2011/// VL - 11 IS - 6 SP - 45-51 ER - TY - JOUR TI - Electroactuation of Solvated Triblock Copolymer Dielectric Elastomers: Decoupling the Roles of Mechanical Prestrain and Specimen Thickness AU - Krishnan, Arjun S. AU - Vargantwar, Pruthesh H. AU - Ghosh, Tushar K. AU - Spontak, Richard J. T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract Dielectric elastomers (DEs) constitute a class of electroactive polymers that are becoming increasingly important as lightweight and mechanically robust replacements for conventional transducers and actuators. Because of their inherent cycling resilience, they also show tremendous promise as energy‐harvesting media, as well as smart sensors and microfluidic devices. Recent studies have demonstrated that DEs composed of midblock‐solvated triblock copolymers exhibit attractive electromechanical attributes such as giant electroactuation strains at relatively low electric fields at high conversion efficiency. Moreover, the properties of these readily processable systems are highly composition‐tunable, thereby making them ideal candidates for a detailed study of the coupling between initial specimen thickness and mechanical prestrain, which is frequently used to reduce specimen thickness before actuation to lower the voltage required to achieve electroactuation. Conventional wisdom based on the notion of an ideal DE indicates that electroactuation should only depend on pre‐actuation specimen thickness, but we report results that unequivocally indicate a more detailed material/process description is required. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1569–1582, 2011 DA - 2011/11/15/ PY - 2011/11/15/ DO - 10.1002/polb.22331 VL - 49 IS - 22 SP - 1569-1582 SN - 1099-0488 KW - biaxiality KW - block copolymers KW - dielectric properties KW - films KW - gels KW - mechanical properties KW - micelles KW - modulus KW - self-assembly KW - stimuli-responsive polymers ER - TY - JOUR TI - Effect of copolymer compatibilizer sequence on the dynamics of phase separation of immiscible binary homopolymer blends AU - Malik, Ravish AU - Hall, Carol K. AU - Genzer, Jan T2 - SOFT MATTER AB - We present the results of kinetic Monte Carlo simulations aimed at exploring the effect of copolymer sequence distribution on the dynamics of phase separation of an immiscible A/B binary homopolymer blend. Diblock, protein-like copolymers (PLCs), simple linear gradient, random, and alternating copolymers having equal number of A and B segments, identical chemical composition, and chain length are considered as compatibilizers. All copolymers, irrespective of their sequence, retard the phase separation process by migrating to the biphasic interface between the A/B interface, thereby minimizing the interfacial energy and promoting adhesion between the homopolymer-rich phases. As expected, diblock copolymers perform the best and each block of the diblock copolymer penetrates the energetically favorable homopolymer-rich phase. Alternating copolymers lie at the interface and PLCs, simple linear gradient, and random copolymers weave back and forth across the interface. The weaving and penetration is more pronounced for PLCs than for simple linear gradient and random copolymers. Judging by the contact analysis, extension and conformation of the copolymers at the interface, and structure factor calculations, it is evident that for the chain lengths considered in our simulations, PLCs are better compatibilizers than alternating and random copolymers, while being on a par with simple linear gradient copolymers, but not as good as diblocks. DA - 2011/// PY - 2011/// DO - 10.1039/c1sm06292a VL - 7 IS - 22 SP - 10620-10630 SN - 1744-6848 ER - TY - JOUR TI - Crystal structure and physical properties of lithium difluoro(oxalato)borate (LiDFOB or LiBF(2)Ox) AU - Allen, Joshua L. AU - Han, Sang-Don AU - Boyle, Paul D. AU - Henderson, Wesley A. T2 - JOURNAL OF POWER SOURCES AB - The structural characterization and properties of lithium difluoro(oxalato)borate (LiDFOB) are reported. LiDFOB was synthesized as previously described in the literature via direct reaction of boron trifluoride diethyl etherate with lithium oxalate. The crystal structure of the salt was determined from single crystal X-ray diffraction yielding a highly symmetric orthorhombic structure (Cmcm, a = 6.2623(8) Å, b = 11.4366(14) Å, c = 6.3002(7) Å, V = 451.22(9) Å3, Z = 4 at 110 K). Single crystal X-ray diffraction of a dihydrate of LiDFOB yielded a monoclinic structure (P21/c, a = 9.5580(3) Å, b = 12.7162(4) Å, c = 5.4387(2) Å, V = 634.63(4) Å3, Z = 4 at 110 K). Along with the crystal structures, additional structural information and the properties of LiDFOB (via 11B and 19F NMR, DSC, TGA and Raman spectroscopy) have been compared with those of LiBF4 and LiBOB to better understand the differences between these lithium battery electrolyte salts. DA - 2011/11/15/ PY - 2011/11/15/ DO - 10.1016/j.jpowsour.2011.07.065 VL - 196 IS - 22 SP - 9737-9742 SN - 1873-2755 KW - Lithium-ion battery KW - LiDFOB KW - Lithium salt KW - Electrolyte KW - Crystal structure ER - TY - JOUR TI - Coating Alumina on Catalytic Iron Oxide Nanoparticles for Synthesizing Vertically Aligned Carbon Nanotube Arrays AU - Wang, Xin AU - Krommenhoek, Peter J. AU - Bradford, Philip D. AU - Gong, Bo AU - Tracy, Joseph B. AU - Parsons, Gregory N. AU - Luo, Tzy-Jiun M. AU - Zhu, Yuntian T. T2 - ACS Applied Materials & Interfaces AB - To synthesize long and uniform vertically aligned carbon nanotube (VACNT) arrays, it is essential to use catalytic nanoparticles (NPs) with monodisperse sizes and to avoid NP agglomeration at the growth temperature. In this work, VACNT arrays were grown on chemically synthesized Fe(3)O(4) NPs of diameter 6 nm by chemical vapor deposition. Coating the NPs with a thin layer of Al(2)O(3) prior to CNT growth preserves the monodisperse sizes, resulting in uniform, thick and dense VACNT arrays. Comparison with uncoated NPs shows that the Al(2)O(3) coating effectively prevents the catalyst NPs from sintering and coalescing, resulting in improved control over VACNT growth. DA - 2011/10/18/ PY - 2011/10/18/ DO - 10.1021/am201082m VL - 3 IS - 11 SP - 4180-4184 J2 - ACS Appl. Mater. Interfaces LA - en OP - SN - 1944-8244 1944-8252 UR - http://dx.doi.org/10.1021/am201082m DB - Crossref KW - carbon nanotubes KW - nanoparticles KW - iron oxide KW - chemical vapor deposition KW - atomic layer deposition ER - TY - JOUR TI - Why I Teach (and Advise) AU - Bullard, L.G. T2 - Chemical Engineering Education DA - 2011/// PY - 2011/// VL - 45 IS - 3 SP - 192 ER - TY - JOUR TI - Water vapor barrier properties of coated and filled microfibrillated cellulose composite films AU - Spence, K. L. AU - Venditti, R. A. AU - Rojas, O. J. AU - Pawlak, J. J. AU - Hubbe, M. A. T2 - BioResources AB - Microfibrillated celluloses (MFCs) have mechanical properties sufficient for packaging applications, but lack in comparison to petroleum-based plastics in water vapor barrier properties. These properties can be modified by the use of mineral fillers, added within the film structure, or waxes, as surface coatings. In this investigation it was found that addition of fillers resulted in films with lower densities but also lower water vapor transmission rates. This was hypothesized to be due to decreased water vapor solubility in the films. Associated transport phenomena were described by the Knudsen model for diffusion but due to the limited incorporation of chemical factors in the model, accurate prediction of pore diameters for filled films was not possible. Modeling the filled-films with Fick’s equation, however, takes into account chemical differences, as observed by the calculated tortuosity values. Remarkably, coating with beeswax, paraffin, and cooked starch resulted in films with water vapor transmission rates lower than those for low density polyethylene. These coatings were modeled with a three-layer model which determined that coatings were more effective in reducing WVTR. DA - 2011/// PY - 2011/// DO - 10.15376/biores.6.4.4370-4388 VL - 6 IS - 4 SP - 4370–4388 ER - TY - JOUR TI - Using a Role-Play Video to Minimize Cheating on Assignments AU - Bullard, L. G. AU - Melvin, A. T T2 - Advances in Engineering Education DA - 2011/// PY - 2011/// VL - 2 IS - 3 ER - TY - JOUR TI - The Importance of Saying Thank You AU - Bullard, L.G. T2 - Chemical Engineering Education DA - 2011/// PY - 2011/// VL - 45 IS - 5 ER - TY - JOUR TI - Sulfonated Polystyrene Fiber Network-Induced Hybrid Proton Exchange Membranes AU - Yao, Yingfang AU - Ji, Liwen AU - Lin, Zhan AU - Li, Ying AU - Alcoutlabi, Mataz AU - Hamouda, Hechmi AU - Zhang, Xiangwu T2 - ACS APPLIED MATERIALS & INTERFACES AB - A novel type of hybrid membrane was fabricated by incorporating sulfonated polystyrene (S-PS) electrospun fibers into Nafion for the application in proton exchange membrane fuel cells. With the introduction of S-PS fiber mats, a large amount of sulfonic acid groups in Nafion aggregated onto the interfaces between S-PS fibers and the ionomer matrix, forming continuous pathways for facile proton transport. The resultant hybrid membranes had higher proton conductivities than that of recast Nafion, and the conductivities were controlled by selectively adjusting the fiber diameters. Consequently, hybrid membranes fabricated by ionomers, such as Nafion, incorporated with ionic-conducting nanofibers established a promising strategy for the rational design of high-performance proton exchange membranes. DA - 2011/9// PY - 2011/9// DO - 10.1021/am2009184 VL - 3 IS - 9 SP - 3732-3737 SN - 1944-8252 UR - https://publons.com/publon/6540072/ KW - hybrid materials KW - proton exchange membrane KW - electrospun fibers KW - sulfonated polystyrene KW - Nafion ER - TY - JOUR TI - Multiple benzene-formation paths in a fuel-rich cyclohexane flame AU - Li, Wenjun AU - Law, Matthew E. AU - Westmoreland, Phillip R. AU - Kasper, Tina AU - Hansen, Nils AU - Kohse-Höinghaus, Katharina T2 - Combustion and Flame AB - Detailed data and modeling of cyclohexane flames establish that a mixture of pathways contributes to benzene formation and that this mixture changes with stoichiometry. Mole-fraction profiles are mapped for more than 40 species in a fuel-rich, premixed flat flame (ϕ = 2.0, cyclohexane/O2/30% Ar, 30 Torr, 50.0 cm/s) using molecular-beam mass spectrometry with VUV-photoionization at the Advanced Light Source of the Lawrence Berkeley National Laboratory. The use of a newly constructed set of reactions leads to an excellent simulation of this flame and an earlier stoichiometric flame (M.E. Law et al., Proc. Combust. Inst. 31 (2007) 565–573), permitting analysis of the contributing mechanistic pathways. Under stoichiometric conditions, benzene formation is found to be dominated by stepwise dehydrogenation of the six-membered ring with cyclohexadienyl ⇄ benzene + H being the final step. This finding is in accordance with recent literature. Dehydrogenation of the six-membered ring is also found to be a dominant benzene-formation route under fuel-rich conditions, at which H2 elimination from 1,3-cyclohexadiene contributes even more than cyclohexadienyl decomposition. Furthermore, at the fuel-rich condition, additional reactions make contributions, including the direct route via 2C3H3 ⇄ benzene and more importantly the H-assisted isomerization of fulvene formed from i-/n-C4H5 + C2H2, C3H3 + allyl, and C3H3 + C3H3. Smaller contributions towards benzene formation arise from C4H3 + C2H3, 1,3-C4H6 + C2H3, and potentially via n-C4H5 + C2H2. This diversity of pathways is shown to result nominally from the temperature and the concentrations of benzene precursors present in the benzene-formation zone, which are ultimately due to the feed stoichiometry. DA - 2011/11// PY - 2011/11// DO - 10.1016/j.combustflame.2011.03.014 VL - 158 IS - 11 SP - 2077-2089 J2 - Combustion and Flame LA - en OP - SN - 0010-2180 UR - http://dx.doi.org/10.1016/j.combustflame.2011.03.014 DB - Crossref KW - Cyclohexane KW - Benzene KW - Mechanism KW - Oxidation KW - MBMS KW - Aromatics ER - TY - JOUR TI - Engineering and Sustainable Community Development AU - Bullard, L.G. T2 - Chemical Engineering Education DA - 2011/// PY - 2011/// VL - 45 IS - 1 SP - 58 ER - TY - JOUR TI - Cells see the light to bring signaling under control AU - Haugh, Jason M T2 - Nature Methods DA - 2011/9// PY - 2011/9// DO - 10.1038/nmeth.1708 VL - 8 IS - 10 SP - 808-809 ER - TY - JOUR TI - (Electro)mechanical behavior of selectively solvated diblock/triblock copolymer blends AU - Vargantwar, Pruthesh H. AU - Brelander, Sarah M. AU - Krishnan, Arjun S. AU - Ghosh, Tushar K. AU - Spontak, Richard J. T2 - APPLIED PHYSICS LETTERS AB - Thermoplastic elastomeric triblock copolymers swollen with a midblock-selective solvent form a highly elastic physical network that can exhibit remarkable electromechanical properties (high actuation strains and electromechanical efficiency with low hysteresis upon cycling) as dielectric elastomers. One unexplored means of controllably altering the midblock network and the corresponding (electro)mechanical properties at constant copolymer concentration is to substitute non-network-forming diblock for triblock copolymer molecules. In this study, we demonstrate that the incorporation of composition-matched diblock molecules into selectively solvated triblock systems results in softer materials that are less physically crosslinked and thus capable of undergoing electroactuation at reduced electric fields. DA - 2011/12/12/ PY - 2011/12/12/ DO - 10.1063/1.3666783 VL - 99 IS - 24 SP - SN - 1077-3118 ER - TY - JOUR TI - Surfactant-enabled epitaxy through control of growth mode with chemical boundary conditions AU - Paisley, Elizabeth A. AU - Losego, Mark. D. AU - Gaddy, Benjamin E. AU - Tweedie, James S. AU - Collazo, Ramon AU - Sitar, Zlatko AU - Irving, Douglas L. AU - Maria, Jon-Paul T2 - NATURE COMMUNICATIONS AB - Property coupling at interfaces between active materials is a rich source of functionality, if defect densities are low, interfaces are smooth and the microstructure is featureless. Conventional synthesis techniques generally fail to achieve this when materials have highly dissimilar structure, symmetry and bond type—precisely when the potential for property engineering is most pronounced. Here we present a general synthesis methodology, involving systematic control of the chemical boundary conditions in situ, by which the crystal habit, and thus growth mode, can be actively engineered. In so doing, we establish the capability for layer-by-layer deposition in systems that otherwise default to island formation and grainy morphology. This technique is demonstrated via atomically smooth {111} calcium oxide films on (0001) gallium nitride. The operative surfactant-based mechanism is verified by temperature-dependent predictions from ab initio thermodynamic calculations. Calcium oxide films with smooth morphology exhibit a three order of magnitude enhancement of insulation resistance. Property coupling by heteroepitaxy is severely limited in material combinations with highly dissimilar bonding. This report presents a chemical boundary condition methodology to actively engineer two-dimensional film growth in such systems that otherwise collapse into island formation and rough morphologies. DA - 2011/9// PY - 2011/9// DO - 10.1038/ncomms1470 VL - 2 SP - SN - 2041-1723 ER - TY - JOUR TI - Spectroscopic detection of medium range order in device quality hydrogenated amorphous silicon, a-Si(H) AU - Lucovsky, G. AU - Parsons, G. AU - Zeller, D. AU - Wu, K. AU - Papas, B. AU - Whitten, J. AU - Lujan, R. AU - Street, R. A. T2 - Journal of Optoelectronics and Advanced Materials DA - 2011/// PY - 2011/// VL - 13 IS - 11-12 SP - 1586-1589 ER - TY - JOUR TI - SiNx charge-trap nonvolatile memory based on ZnO thin-film transistors AU - Kim, Eunkyeom AU - Kim, Youngill AU - Kim, Do Han AU - Lee, Kyoungmi AU - Parsons, Gregory N. AU - Park, Kyoungwan T2 - APPLIED PHYSICS LETTERS AB - We have demonstrated the fabrication and application of a nonvolatile thin-film transistor memory with SiNx charge traps using a ZnO thin film as the active channel layer. The thin film of ZnO was deposited using an atomic-layer deposition process and was subsequently post-annealed in an O2-filled atmosphere. X-ray diffraction and x-ray photoemission results indicated that the O2 annealing process was effective for the crystallinity and stoichiometry of the ZnO films. A saturation field-effect mobility of 6 cm2/Vs, on/off ratio of ≈105, subthreshold slope of 0.7 V/decade, and threshold voltage of −5 V were obtained in transistor operations. Threshold-voltage shift measurements performed for various stress voltages and time durations revealed that these devices had a large memory window of 5.4 V and a long retention time (&gt;10 years) in nonvolatile memory operations. DA - 2011/9/12/ PY - 2011/9/12/ DO - 10.1063/1.3640221 VL - 99 IS - 11 SP - SN - 0003-6951 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000295034400043&KeyUID=WOS:000295034400043 ER - TY - JOUR TI - Pressure enhancement in carbon nanopores: a major confinement effect AU - Long, Yun AU - Palmer, Jeremy C. AU - Coasne, Benoit AU - Sliwinska-Bartkowiak, Malgorzata AU - Gubbins, Keith E. T2 - PHYSICAL CHEMISTRY CHEMICAL PHYSICS AB - Phenomena that occur only at high pressures in bulk phases are often observed in nanopores, suggesting that the pressure in such confined phases is large. We report a molecular simulation study of the pressure tensor of an argon nanophase within slit-shaped carbon pores and show that the tangential pressure is positive and large, while the normal pressure can be positive or negative depending on pore width. We also show that small changes in the bulk pressure have a large effect on the tangential pressure, suggesting that it should be possible to control the latter over wide ranges in laboratory experiments. DA - 2011/// PY - 2011/// DO - 10.1039/c1cp21407a VL - 13 IS - 38 SP - 17163-17170 SN - 1463-9084 ER - TY - JOUR TI - Highly proton conductive electrolyte membranes: Fiber-induced long-range ionic channels AU - Yao, Yingfang AU - Guo, Bingkun AU - Ji, Liwen AU - Jung, Kyung-Hye AU - Lin, Zhan AU - Alcoutlabi, Mataz AU - Hamouda, Hechmi AU - Zhang, Xiangwu T2 - ELECTROCHEMISTRY COMMUNICATIONS AB - Novel conductive inorganic fiber/polymer hybrid proton exchange membranes (PEMs) were obtained by taking advantage of sulfated zirconia (S-ZrO2) fibers made by electrospinning and post-electrospinning processes. Induced by electrospun inorganic fibers, long-range ionic channels were formed by agglomerating functional groups, which served as continuous hopping pathways for protons and significantly improved the proton conductivity of PEMs. DA - 2011/9// PY - 2011/9// DO - 10.1016/j.elecom.2011.06.028 VL - 13 IS - 9 SP - 1005-1008 SN - 1388-2481 UR - https://publons.com/publon/6540067/ KW - Proton exchange membranes KW - Electrospun fibers KW - Functional polymers KW - Ionic channels KW - Proton conductivity ER - TY - JOUR TI - Characterizing the Molecular Order of Phosphonic Acid Self-Assembled Monolayers on Indium Tin Oxide Surfaces AU - Losego, Mark D. AU - Guske, Joshua T. AU - Efremenko, Alina AU - Maria, Jon-Paul AU - Franzen, Stefan T2 - LANGMUIR AB - Self-assembled monolayers (SAMs) of alkanephosphonic acids with chain lengths between 8 and 18 carbon units were formed on thin films of indium tin oxide (ITO) sputter-deposited on silicon substrates with 400 nm thermally grown SiO(2). The silicon substrates, while not intended for use in near-IR or visible optics applications, do provide smooth surfaces that permit systematic engineering of grain size and surface roughness as a function of the sputter pressure. Argon sputter pressures from 4 to 20 mTorr show systematic changes in surface morphology ranging from smooth, micrometer-sized grain structures to <50 nm grains with 3× higher surface roughness. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy experiments are conducted for alkanephosphonic acids deposited on these wide range of ITO surfaces to evaluate the effects of these morphological features on monolayer ordering. Results indicate that long-chain SAMs are more highly ordered, and have a smaller tilt angle, than short-chain SAMs. Surprisingly, the 1-octadecyl phosphonic acids maintain their order as the lateral grain dimensions of the ITO surface shrink to ∼50 nm. It is only when the ITO surface roughness becomes greater than the SAM chain length (∼15 Å) that SAMs are observed to become relatively disordered. DA - 2011/10/4/ PY - 2011/10/4/ DO - 10.1021/la201161q VL - 27 IS - 19 SP - 11883-11888 SN - 0743-7463 ER - TY - JOUR TI - Toward Understanding Reactive Adsorption of Ammonia on Cu-MOF/Graphite Oxide Nanocomposites AU - Petit, Camille AU - Huang, Liangliang AU - Jagiello, Jacek AU - Kenvin, Jeffrey AU - Gubbins, Keith E. AU - Bandosz, Teresa J. T2 - LANGMUIR AB - The adsorption of ammonia on HKUST-1 (a metal-organic framework, MOF) and HKUST-1/graphite oxide (GO) composites was investigated in two different experimental conditions. From the isotherms, the isosteric heats of adsorption were calculated from the Clausius-Clapeyron equation following the virial approach. The results on HKUST-1 were compared with those obtained using molecular simulation studies. All materials exhibit higher ammonia adsorption capacities than those reported in the literature. The ammonia adsorption on the composites is higher than that measured separately on the MOF component and on GO. The strong adsorption of ammonia caused by chemical interactions on different adsorption sites is evidenced by the trends in the isosteric heats of adsorption. The molecular simulations conducted on HKUST-1 support the trends observed experimentally. In particular, the strong chemisorption of ammonia on the metallic centers of HKUST-1 is confirmed. Nevertheless, higher adsorption capacities are predicted compared with the experimental results. This discrepancy is mainly assigned to the partial collapse of the MOF structure upon exposure to ammonia, which is not accounted for in the simulation study. DA - 2011/11/1/ PY - 2011/11/1/ DO - 10.1021/la202924y VL - 27 IS - 21 SP - 13043-13051 SN - 0743-7463 ER - TY - JOUR TI - Sinter-free phase conversion and scanning transmission electron microscopy of FePt nanoparticle monolayers AU - Johnston-Peck, Aaron C. AU - Scarel, Giovanna AU - Wang, Junwei AU - Parsons, Gregory N. AU - Tracy, Joseph B. T2 - NANOSCALE AB - Thermally robust monolayers of 4–6 nm diameter FePt nanoparticles (NPs) were fabricated by combining chemical synthesis and atomic layer deposition. Spin-cast monolayers of FePt NPs were coated with thin, 11 nm-thick layers of amorphous Al2O3, followed by annealing to convert the FePt NPs from an alloy (A1) into intermetallic FePt (L10) and FePt3 (L12) phases. The Al2O3 layer serves as a barrier that prevents sintering between NPs during annealing at temperatures up to 730 °C. Electron and X-ray diffraction in conjunction with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) show that as-synthesized A1 FePt NPs convert into L10 and L12 phase NPs through annealing. HAADF-STEM measurements of individual NPs reveal imperfect ordering and show that the NP composition determines which intermetallic phase is obtained. Mixed-phase NPs with L10 cores and FePt3 L12 shells were also observed, as well as a smaller number of unconverted A1 NPs. These results highlight the need for improved control over the compositional uniformity of FePt NPs for their use in bit-patterned magnetic recording. DA - 2011/// PY - 2011/// DO - 10.1039/c1nr10567a VL - 3 IS - 10 SP - 4142-4149 SN - 2040-3372 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000295618200024&KeyUID=WOS:000295618200024 ER - TY - JOUR TI - Phase Separation Dynamics for a Polymer Blend Compatibilized by Protein-like Copolymers: A Monte Carlo Simulation AU - Malik, Ravish AU - Hall, Carol K. AU - Genzer, Jan T2 - MACROMOLECULES AB - We use Monte Carlo simulation based on the bond fluctuation model to investigate how adding ≈4.92% protein-like copolymer (PLC) to an immiscible binary polymer blend affects the dynamics of phase separation. PLCs slow down effectively the process of phase separation in binary blends by migrating to the biphasic interface between the immiscible homopolymers, thereby reducing the interfacial tension. The ability of PLCs to retard effectively the process of phase separation depends sensitively on the interaction energy between the PLCs and homopolymers and the PLC chain length. PLCs compatibilize the binary blend more effectively with increasing attractive interaction between the PLC blocks and homopolymers. Nominal improvement in compatibilization of the binary blend is achieved with increasing PLC chain length. The growth of phase-separated domains follows a dynamical scaling law for both the binary blend and PLC compatibilized ternary blend in the late stages of phase separation. The universal scaling functions are nearly independent of the interaction energy and PLC chain length. Thus, the phase-separated domains grow with dynamical self-similarity irrespective of the type of PLC added to the binary blend, although the type of PLC significantly alters the growth rate of the phase-separated domains. DA - 2011/10/25/ PY - 2011/10/25/ DO - 10.1021/ma2014832 VL - 44 IS - 20 SP - 8284-8293 SN - 0024-9297 ER - TY - JOUR TI - On-chip collection of particles and cells by AC electroosmotic pumping and dielectrophoresis using asymmetric microelectrodes AU - Melvin, E.M. AU - Moore, B.R. AU - Gilchrist, K.H. AU - Grego, S. AU - Velev, Orlin T2 - Biomicrofluidics AB - The recent development of microfluidic "lab on a chip" devices requiring sample sizes <100 μL has given rise to the need to concentrate dilute samples and trap analytes, especially for surface-based detection techniques. We demonstrate a particle collection device capable of concentrating micron-sized particles in a predetermined area by combining AC electroosmosis (ACEO) and dielectrophoresis (DEP). The planar asymmetric electrode pattern uses ACEO pumping to induce equal, quadrilateral flow directed towards a stagnant region in the center of the device. A number of system parameters affecting particle collection efficiency were investigated including electrode and gap width, chamber height, applied potential and frequency, and number of repeating electrode pairs and electrode geometry. The robustness of the on-chip collection design was evaluated against varying electrolyte concentrations, particle types, and particle sizes. These devices are amenable to integration with a variety of detection techniques such as optical evanescent waveguide sensing. DA - 2011/// PY - 2011/// DO - 10.1063/1.3620419 VL - 5 IS - 3 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80053440340&partnerID=MN8TOARS KW - biochemistry KW - electrophoresis KW - lab-on-a-chip KW - microelectrodes KW - microfluidics KW - osmosis ER - TY - JOUR TI - Magnetically responsive pickering foams AU - Lam, S. AU - Blanco, E. AU - Smoukov, S.K. AU - Velikov, K.P. AU - Velev, O.D. T2 - Journal of the American Chemical Society AB - We introduce a new class of Pickering foams which can be manipulated using a magnetic field. These foams are stabilized by a mixture of magnetic and nonmagnetic particles. They exhibit excellent stability in the absence of a magnetic field, but can be rapidly destroyed on demand with the application of a threshold field. We characterize their stability in the absence of a magnetic field by measuring the rate of water drainage from the foam as a function of time. We also correlate their collapse behavior under a magnetic field to the foam liquid fraction, as well as the concentration of magnetic particles in the foam. This novel system can be used to study the properties of Pickering foams, and has potential applications in noncontact defoaming processes. DA - 2011/// PY - 2011/// DO - 10.1021/ja205065w VL - 133 IS - 35 SP - 13856-13859 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80052341697&partnerID=MN8TOARS ER - TY - JOUR TI - Effects of peptide density and elution pH on affinity chromatographic purification of human immunoglobulins A and M AU - Liu, Zhuo AU - Gurgel, Patrick V. AU - Carbonell, Ruben G. T2 - JOURNAL OF CHROMATOGRAPHY A AB - A family of linear hexamer peptide ligands HWRGWV, HYFKFD and HFRRHL, initially identified for their affinity to the Fc portion of human immunoglobulin G (hIgG), also have potential for use in the purification of human immunoglobulins A (hIgA) and M (hIgM). HWRGWV demonstrated the strongest binding affinity to hIgM, followed by hIgA and hIgG respectively. The effects of N-terminal acetylation of the peptide, as well as elution buffer pH, on the chromatographic elution of human IgG, IgA and IgM from HWRGWV resins at various peptide densities (0.04–0.55 meq/g) were investigated. Over 80% recovery and 90% purity were achieved for human IgG and IgA isolation from complete minimum essential medium (cMEM) using HWRGWV resin at optimum peptide densities. For human IgM, 75.7% recovery and 86.0% purity were achieved by using HWRGWV at a low peptide density of 0.04 meq/g. Although HYFKFD and HFRRHL exhibited their ability for isolation of human IgG, IgA and IgM from cMEM as well, HWRGWV is the best option among them for large-scale purification of human IgG, IgA and IgM based on conditions tested. DA - 2011/11/18/ PY - 2011/11/18/ DO - 10.1016/j.chroma.2011.09.038 VL - 1218 IS - 46 SP - 8344-8352 SN - 1873-3778 KW - Human immunoglobulin KW - IgG KW - IgA KW - IgM KW - Affinity chromatography KW - Binding site ER - TY - JOUR TI - Towards All-Soft Matter Circuits: Prototypes of Quasi-Liquid Devices with Memristor Characteristics AU - Koo, Hyung-Jun AU - So, Ju-Hee AU - Dickey, Michael D. AU - Velev, Orlin D. T2 - ADVANCED MATERIALS AB - A new class of memristors based entirely on soft and liquid-based matter is presented. The devices are formed by interfacing liquid metal electrodes with water-based gel doped with polyelectrolytes. They memorize the last state of bias polarization on the basis of the asymmetric conductance of the hydrogel-oxide-liquid metal stack. Such devices may find application in circuit-live tissue interfaces, soft robotics, and neuromorphic systems. DA - 2011/8/16/ PY - 2011/8/16/ DO - 10.1002/adma.201101257 VL - 23 IS - 31 SP - 3559-+ SN - 1521-4095 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80051693085&partnerID=MN8TOARS ER - TY - JOUR TI - Tetrakis(acetonitrile-kappa N) lithium hexafluoridophosphate acetonitrile monosolvate AU - Seo, D. M. AU - Boyle, P. D. AU - Henderson, W. A. T2 - Acta Crystallographica. Section E, Structure Reports Online DA - 2011/// PY - 2011/// VL - 67 SP - M1148-1301 ER - TY - JOUR TI - Structure and Dynamics of Reentrant Nematics: Any Open Questions after Almost 40 Years? AU - Mazza, Marco G. AU - Schoen, Martin T2 - INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES AB - Liquid crystals have attracted enormous interest because of the variety of their phases and richness of their application. The interplay of general physical symmetries and specific molecular features generates a myriad of different phenomena. A surprising behavior of liquid crystals is the reentrancy of phases as temperature, pressure, or concentration are varied. Here, we review the main experimental facts and the different theoretical scenarios that have guided the understanding of bulk reentrant nematics. Recently, some computer simulations of a system confined to nanoscopic scales have found new dynamical features of the reentrant nematic phase. We discuss this prediction in relation with the available experimental evidence on reentrant nematics and with the dynamics of liquids in strongly confined environments. DA - 2011/8// PY - 2011/8// DO - 10.3390/ijms12085352 VL - 12 IS - 8 SP - 5352-5372 SN - 1422-0067 KW - reentrant phase KW - nematic KW - dynamics KW - diffusion ER - TY - JOUR TI - Separation of Chemical Reaction Intermediates by Metal-Organic Frameworks AU - Centrone, Andrea AU - Santiso, Erik E. AU - Hatton, T. Alan T2 - SMALL AB - Abstract HPLC columns custom‐packed with metal–organic framework (MOF) materials are used for the separation of four small intermediates and byproducts found in the commercial synthesis of an important active pharmaceutical ingredient in methanol. In particular, two closely related amines can be separated in the methanol reaction medium using MOFs, but not with traditional C18 columns using an optimized aqueous mobile phase. Infrared spectroscopy, UV–vis spectroscopy, X‐ray diffraction, and thermogravimetric analysis are used in combination with molecular dynamic simulations to study the separation mechanism for the best‐performing MOF materials. It is found that separation with ZIF‐8 is the result of an interplay between the thermodynamic driving force for solute adsorption within the framework pores and the kinetics of solute diffusion into the material pores, while the separation with Basolite F300 is achieved because of the specific interactions between the solutes and Fe 3+ sites. This work, and the exceptional ability to tailor the porous properties of MOF materials, points to prospects for using MOF materials for the continuous separation and synthesis of pharmaceutical compounds. DA - 2011/8/22/ PY - 2011/8/22/ DO - 10.1002/smll.201100098 VL - 7 IS - 16 SP - 2356-2364 SN - 1613-6829 ER - TY - JOUR TI - Selectively solvated triblock copolymer networks under biaxial strain AU - Krishnan, Arjun S. AU - Zanten, John H. AU - Seifert, Soenke AU - Lee, Byeongdu AU - Spontak, Richard J. T2 - APPLIED PHYSICS LETTERS AB - Triblock copolymers swollen with a midblock-selective solvent provide a test platform by which to interrogate the properties of highly elastic physical gel networks. Here, such networks are biaxially strained and studied by synchrotron small-angle x-ray scattering. Analysis of the form factor reveals that initially spherical micellar cores deform to ellipsoids when strained. The Percus-Yevick hard-sphere model describes the structure factor of micelles exhibiting liquid-like order prior to deformation but requires an attractive potential to match the structure factor under strain. The magnitude of this potential increases with increasing strain, indicating a change in coronal overlap as the network is stretched. DA - 2011/9/5/ PY - 2011/9/5/ DO - 10.1063/1.3635780 VL - 99 IS - 10 SP - SN - 0003-6951 ER - TY - JOUR TI - Microplastics in the marine environment AU - Andrady, Anthony L. T2 - MARINE POLLUTION BULLETIN AB - This review discusses the mechanisms of generation and potential impacts of microplastics in the ocean environment. Weathering degradation of plastics on the beaches results in their surface embrittlement and microcracking, yielding microparticles that are carried into water by wind or wave action. Unlike inorganic fines present in sea water, microplastics concentrate persistent organic pollutants (POPs) by partition. The relevant distribution coefficients for common POPs are several orders of magnitude in favour of the plastic medium. Consequently, the microparticles laden with high levels of POPs can be ingested by marine biota. Bioavailability and the efficiency of transfer of the ingested POPs across trophic levels are not known and the potential damage posed by these to the marine ecosystem has yet to be quantified and modelled. Given the increasing levels of plastic pollution of the oceans it is important to better understand the impact of microplastics in the ocean food web. DA - 2011/8// PY - 2011/8// DO - 10.1016/j.marpolbul.2011.05.030 VL - 62 IS - 8 SP - 1596-1605 SN - 1879-3363 KW - Microplastics KW - Nanoplastics KW - POPs KW - Plastics KW - Food web ER - TY - JOUR TI - Insights into plant biomass conversion from the genome of the anaerobic thermophilic bacterium Caldicellulosiruptor bescii DSM 6725 AU - Dam, Phuongan AU - Kataeva, Irina AU - Yang, Sung-Jae AU - Zhou, Fengfeng AU - Yin, Yanbin AU - Chou, Wenchi AU - Poole, Farris L., II AU - Westpheling, Janet AU - Hettich, Robert AU - Giannone, Richard AU - Lewis, Derrick L. AU - Kelly, Robert AU - Gilbert, Harry J. AU - Henrissat, Bernard AU - Xu, Ying AU - Adams, Michael W. W. T2 - NUCLEIC ACIDS RESEARCH AB - Caldicellulosiruptor bescii DSM 6725 utilizes various polysaccharides and grows efficiently on untreated high-lignin grasses and hardwood at an optimum temperature of ∼ 80 °C. It is a promising anaerobic bacterium for studying high-temperature biomass conversion. Its genome contains 2666 protein-coding sequences organized into 1209 operons. Expression of 2196 genes (83%) was confirmed experimentally. At least 322 genes appear to have been obtained by lateral gene transfer (LGT). Putative functions were assigned to 364 conserved/hypothetical protein (C/HP) genes. The genome contains 171 and 88 genes related to carbohydrate transport and utilization, respectively. Growth on cellulose led to the up-regulation of 32 carbohydrate-active (CAZy), 61 sugar transport, 25 transcription factor and 234 C/HP genes. Some C/HPs were overproduced on cellulose or xylan, suggesting their involvement in polysaccharide conversion. A unique feature of the genome is enrichment with genes encoding multi-modular, multi-functional CAZy proteins organized into one large cluster, the products of which are proposed to act synergistically on different components of plant cell walls and to aid the ability of C. bescii to convert plant biomass. The high duplication of CAZy domains coupled with the ability to acquire foreign genes by LGT may have allowed the bacterium to rapidly adapt to changing plant biomass-rich environments. DA - 2011/4// PY - 2011/4// DO - 10.1093/nar/gkq1281 VL - 39 IS - 8 SP - 3240-3254 SN - 1362-4962 ER - TY - JOUR TI - In Chemotaxing Fibroblasts, Both High-Fidelity and Weakly Biased Cell Movements Track the Localization of PI3K Signaling AU - Melvin, Adam T. AU - Welf, Erik S. AU - Wang, Yana AU - Irvine, Darrell J. AU - Haugh, Jason M. T2 - BIOPHYSICAL JOURNAL AB - Cell movement biased by a chemical gradient, or chemotaxis, coordinates the recruitment of cells and collective migration of cell populations. During wound healing, chemotaxis of fibroblasts is stimulated by platelet-derived growth factor (PDGF) and certain other chemoattractants. Whereas the immediate PDGF gradient sensing response has been characterized previously at the level of phosphoinositide 3-kinase (PI3K) signaling, the sensitivity of the response at the level of cell migration bias has not yet been studied quantitatively. In this work, we used live-cell total internal reflection fluorescence microscopy to monitor PI3K signaling dynamics and cell movements for extended periods. We show that persistent and properly aligned (i.e., high-fidelity) fibroblast migration does indeed correlate with polarized PI3K signaling; accordingly, this behavior is seen only under conditions of high gradient steepness (>10% across a typical cell length of 50 μm) and a certain range of PDGF concentrations. Under suboptimal conditions, cells execute a random or biased random walk, but nonetheless move in a predictable fashion according to the changing pattern of PI3K signaling. Inhibition of PI3K during chemotaxis is accompanied by loss of both cell-substratum contact and morphological polarity, but after a recovery period, PI3K-inhibited fibroblasts often regain the ability to orient toward the PDGF gradient. DA - 2011/4/20/ PY - 2011/4/20/ DO - 10.1016/j.bpj.2011.02.047 VL - 100 IS - 8 SP - 1893-1901 SN - 0006-3495 ER - TY - JOUR TI - Improved kinetic model of crystallization for isotactic polypropylene induced by supercritical CO(2): Introducing pressure and temperature dependence into the Avrami equation AU - Zhang, R. H. AU - Li, X. K. AU - Cao, G. P. AU - Shi, Y. H. AU - Liu, H. L. AU - Yuan, W. K. AU - Roberts, G. W. T2 - Industrial & Engineering Chemistry Research DA - 2011/// PY - 2011/// VL - 50 IS - 18 SP - 10509-10515 ER - TY - JOUR TI - Guidelines for visualizing and annotating rule-based models AU - Chylek, Lily A. AU - Hu, Bin AU - Blinov, Michael L. AU - Emonet, Thierry AU - Faeder, James R. AU - Goldstein, Byron AU - Gutenkunst, Ryan N. AU - Haugh, Jason M. AU - Lipniacki, Tomasz AU - Posner, Richard G. AU - Yang, Jin AU - Hlavacek, William S. T2 - MOLECULAR BIOSYSTEMS AB - Rule-based modeling provides a means to represent cell signaling systems in a way that captures site-specific details of molecular interactions. For rule-based models to be more widely understood and (re)used, conventions for model visualization and annotation are needed. We have developed the concepts of an extended contact map and a model guide for illustrating and annotating rule-based models. An extended contact map represents the scope of a model by providing an illustration of each molecule, molecular component, direct physical interaction, post-translational modification, and enzyme-substrate relationship considered in a model. A map can also illustrate allosteric effects, structural relationships among molecular components, and compartmental locations of molecules. A model guide associates elements of a contact map with annotation and elements of an underlying model, which may be fully or partially specified. A guide can also serve to document the biological knowledge upon which a model is based. We provide examples of a map and guide for a published rule-based model that characterizes early events in IgE receptor (FcεRI) signaling. We also provide examples of how to visualize a variety of processes that are common in cell signaling systems but not considered in the example model, such as ubiquitination. An extended contact map and an associated guide can document knowledge of a cell signaling system in a form that is visual as well as executable. As a tool for model annotation, a map and guide can communicate the content of a model clearly and with precision, even for large models. DA - 2011/// PY - 2011/// DO - 10.1039/c1mb05077j VL - 7 IS - 10 SP - 2779-2795 SN - 1742-2051 ER - TY - JOUR TI - Fabrication and electrochemical characteristics of electrospun LiFePO4/carbon composite fibers for lithium-ion batteries AU - Toprakci, Ozan AU - Ji, Liwen AU - Lin, Zhan AU - Toprakci, Hatice A. K. AU - Zhang, Xiangwu T2 - JOURNAL OF POWER SOURCES AB - LiFePO4/C composite fibers were synthesized by using a combination of electrospinning and sol–gel techniques. Polyacrylonitrile (PAN) was used as an electrospinning media and a carbon source. LiFePO4 precursor materials and PAN were dissolved in N,N-dimethylformamide separately and they were mixed before electrospinning. LiFePO4 precursor/PAN fibers were heat treated, during which LiFePO4 precursor transformed to energy-storage LiFePO4 material and PAN was converted to carbon. The surface morphology and microstructure of the obtained LiFePO4/C composite fibers were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and elemental dispersive spectroscopy (EDS). XRD measurements were also carried out in order to determine the structure of LiFePO4/C composite fibers. Electrochemical performance of LiFePO4/carbon composite fibers was evaluated in coin-type cells. Carbon content and heat treatment conditions (such as stabilization temperature, calcination/carbonization temperature, calcination/carbonization time, etc.) were optimized in terms of electrochemical performance. DA - 2011/9/15/ PY - 2011/9/15/ DO - 10.1016/j.jpowsour.2011.04.031 VL - 196 IS - 18 SP - 7692-7699 SN - 1873-2755 UR - https://publons.com/publon/674397/ KW - LiFePO4 KW - Cathodes KW - Fibers KW - Electrospinning KW - Lithium-ion batteries ER - TY - JOUR TI - Extremely Thermophilic Routes to Microbial Electrofuels AU - Hawkins, Aaron S. AU - Han, Yejun AU - Lian, Hong AU - Loder, Andrew J. AU - Menon, Angeli L. AU - Iwuchukwu, Ifeyinwa J. AU - Keller, Matthew AU - Leuko, Therese T. AU - Adams, Michael W. W. AU - Kelly, Robert M. T2 - ACS CATALYSIS AB - ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTExtremely Thermophilic Routes to Microbial ElectrofuelsAaron S. Hawkins†, Yejun Han†, Hong Lian†, Andrew J. Loder†, Angeli L. Menon‡, Ifeyinwa J. Iwuchukwu‡, Matthew Keller‡, Therese T. Leuko‡, Michael W.W. Adams‡, and Robert M. Kelly*†View Author Information† Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, United States‡ Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United StatesPhone: (919) 515-6396. Fax: (919) 515-3465. E-mail: [email protected]Cite this: ACS Catal. 2011, 1, 9, 1043–1050Publication Date (Web):August 1, 2011Publication History Received7 June 2011Published online8 August 2011Published inissue 2 September 2011https://doi.org/10.1021/cs2003017Copyright © 2011 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views2550Altmetric-Citations34LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. 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Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSUBJECTS:Bacteria,Genetics,Hydrogen,Oxides,Peptides and proteins Get e-Alerts DA - 2011/9// PY - 2011/9// DO - 10.1021/cs2003017 VL - 1 IS - 9 SP - 1043-1050 SN - 2155-5435 ER - TY - JOUR TI - Discriminating tastes: physiological contributions of the Hfq-binding small RNA Spot 42 to catabolite repression AU - Beisel, C. L. AU - Storz, G. T2 - RNA Biology DA - 2011/// PY - 2011/// VL - 8 SP - 1-5 ER - TY - JOUR TI - Dielectrophoresis of cellulose nanocrystals and alignment in ultrathin films by electric field-assisted shear assembly AU - Csoka, Levente AU - Hoeger, Ingrid C. AU - Peralta, Perry AU - Peszlen, Ilona AU - Rojas, Orlando J. T2 - JOURNAL OF COLLOID AND INTERFACE SCIENCE AB - Ultrathin films of cellulose nanocrystals (CNCs) are obtained by using a convective assembly setup coupled with a low-strength external AC electric field. The orientation and degree of alignment of the rod-like nanoparticles are controlled by the applied field strength and frequency used during film formation. Calculated dipole moments and Clausius-Mossotti factors allowed the determination of the critical frequencies, the peak dielectrophoresis as well as the principal orientation of the CNCs in the ultrathin films. As a result of the combination of shear forces and low electric field highly ultrathin films with controlled, unprecedented CNC alignment are achieved. DA - 2011/11/1/ PY - 2011/11/1/ DO - 10.1016/j.jcis.2011.07.045 VL - 363 IS - 1 SP - 206-212 SN - 1095-7103 KW - Cellulose nanocrystals KW - Dielectrophoresis KW - Ultrathin films KW - Electric field KW - Shear assembly ER - TY - JOUR TI - Convective Assembly of 2D Lattices of Virus-like Particles Visualized by In-Situ Grazing-Incidence Small-Angle X-Ray Scattering AU - Ashley, Carlee E. AU - Dunphy, Darren R. AU - Jiang, Zhang AU - Carnes, Eric C. AU - Yuan, Zhen AU - Petsev, Dimiter N. AU - Atanassov, Plamen B. AU - Velev, Orlin D. AU - Sprung, Michael AU - Wang, Jin AU - Peabody, David S. AU - Brinker, C. Jeffrey T2 - SMALL AB - Abstract The rapid assembly of icosohedral virus‐like particles (VLPs) into highly ordered (domain size > 600 nm), oriented 2D superlattices directly onto a solid substrate using convective coating is demonstrated. In‐situ grazing‐incidence small‐angle X‐ray scattering (GISAXS) is used to follow the self‐assembly process in real time to characterize the mechanism of superlattice formation, with the ultimate goal of tailoring film deposition conditions to optimize long‐range order. From water, GISAXS data are consistent with a transport‐limited assembly process where convective flow directs assembly of VLPs into a lattice oriented with respect to the water drying line. Addition of a nonvolatile solvent (glycerol) modified this assembly pathway, resulting in non‐oriented superlattices with improved long‐range order. Modification of electrostatic conditions (solution ionic strength, substrate charge) also alters assembly behavior; however, a comparison of in‐situ assembly data between VLPs derived from the bacteriophages MS2 and Qβ show that this assembly process is not fully described by a simple Derjaguin–Landau–Verwey–Overbeek model alone. DA - 2011/4/18/ PY - 2011/4/18/ DO - 10.1002/smll.201001665 VL - 7 IS - 8 SP - 1043-1050 SN - 1613-6829 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79954550986&partnerID=MN8TOARS ER - TY - JOUR TI - Computer Simulations of Homogeneous Nucleation of Benzene from the Melt AU - Shah, Manas AU - Santiso, Erik E. AU - Trout, Bernhardt L. T2 - JOURNAL OF PHYSICAL CHEMISTRY B AB - Nucleation is the key step in crystallization by which the molecules (or atoms or ions) aggregate together, find the right relative orientations, and start to grow to form the final crystal structure. Since nucleation is an activated step involving a large gap in time scales between molecular motions and the nucleation event itself, nucleation must be studied using rare events methods. We employ a technique developed previously in our group known as aimless shooting [Peters, B.; Trout, B. L. J. Chem. Phys., 2006, 125, 054108], which is based on transition path sampling, to generate reactive trajectories between the disordered and ordered phases of benzene. Using the likelihood maximization algorithm, we analyze the aimless shooting trajectories to identify the key order parameters or collective variables to describe the reaction coordinate for the nucleation of benzene from the melt. We find that the local bond orientation and local relative orientation order parameters are the most important collective variables in describing the reaction coordinate for homogeneous nucleation from the melt, as compared to cluster size and space-averaged order parameters. This study also demonstrates the utility of recently developed order parameters for molecular crystals [Santiso, E. E.; Trout, B. L. J. Chem. Phys., 2011, 134, 064109]. DA - 2011/9/8/ PY - 2011/9/8/ DO - 10.1021/jp203550t VL - 115 IS - 35 SP - 10400-10412 SN - 1520-6106 ER - TY - JOUR TI - Comparison of stable-isotope labeling with amino acids in cell culture and spectral counting for relative quantification of protein expression AU - Collier, Timothy S. AU - Randall, Shan M. AU - Sarkar, Prasenjit AU - Rao, Balaji M. AU - Dean, Ralph A. AU - Muddiman, David C. T2 - RAPID COMMUNICATIONS IN MASS SPECTROMETRY AB - Protein quantification is one of the principal goals of mass spectrometry (MS)‐based proteomics, and many strategies exist to achieve it. Several approaches involve the incorporation of a stable‐isotope label using either chemical derivatization, enzymatically catalyzed incorporation of 18 O, or metabolic labeling in a cell or tissue culture. These techniques can be cost or time prohibitive or not amenable to the biological system of interest. Label‐free techniques including those utilizing integrated ion abundance and spectral counting offer an alternative to stable‐isotope‐based methodologies. Herein, we present the comparison of stable‐isotope labeling of amino acids in cell culture (SILAC) with spectral counting for the quantification of human embryonic stem cells as they differentiate toward the trophectoderm at three time points. Our spectral counting experimental strategy resulted in the identification of 2641 protein groups across three time points with an average sequence coverage of 30.3%, of which 1837 could be quantified with more than five spectral counts. SILAC quantification was able to identify 1369 protein groups with an average coverage of 24.7%, of which 1027 could be quantified across all time points. Within this context we further explore the capacity of each strategy for proteome coverage, variation in quantification, and the relative sensitivity of each technique to the detection of change in relative protein expression. Copyright © 2011 John Wiley & Sons, Ltd. DA - 2011/9/15/ PY - 2011/9/15/ DO - 10.1002/rcm.5151 VL - 25 IS - 17 SP - 2524-2532 SN - 1097-0231 ER - TY - JOUR TI - Colloidal dispersions by engineering and design AU - Velikov, Krassimir P. AU - Velev, Orlin D. T2 - CURRENT OPINION IN COLLOID & INTERFACE SCIENCE DA - 2011/4// PY - 2011/4// DO - 10.1016/j.cocis.2011.01.007 VL - 16 IS - 2 SP - 81-83 SN - 1359-0294 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79952708499&partnerID=MN8TOARS ER - TY - JOUR TI - Charge- and temperature-dependent interactions between anionic poly (N-isopropylacrylamide) polymers in solution and a cationic surfactant at the water/air interface AU - Volden, Sondre AU - Genzer, Jan AU - Zhu, Kaizheng AU - Ese, Marit-Helen G. AU - Nystrom, Bo AU - Glomm, Wilhelm R. T2 - SOFT MATTER AB - Due to their expanded coil to collapsed globule transition close to physiological temperatures, N-isopropylacrylamide (NIPAAM) polymers and derivatives thereof represent promising drug delivery vectors. Here, we report on the interaction between anionic PNIPAAM derivatives containing potassium 3-sulfopropylmethacrylate (SPMA) blocks of various sizes and a cationic lipid membrane mimic as a function of temperature, polymer charge density and molecular weight, by injection under a pre-compressed surfactant monolayer. The resulting film properties (including equilibria) were studied using surface pressure–area isotherms, Brewster angle microscopy, and interfacial 2D oscillatory rheology. Whereas mixed films of dioctadecyldimethylammonium bromide (DODAB) and an uncharged PNIPAAM homopolymer resulted in distinct polymer and surfactant domains, the anionic polyelectrolytes were found to ionically cross-link and contract the DODAB film. Film penetration, charge screening and surfactant film contraction were dependent on the molecular weight and size of the SPMA blocks on the polymers. DA - 2011/// PY - 2011/// DO - 10.1039/c1sm05671a VL - 7 IS - 18 SP - 8498-8507 SN - 1744-683X ER - TY - JOUR TI - Amphiphilic Co-networks with Moisture-Induced Surface Segregation for High-Performance Nonfouling Coatings AU - Wang, Yapei AU - Finlay, John A. AU - Betts, Douglas E. AU - Merkel, Timothy J. AU - Luft, J. Christopher AU - Callow, Maureen E. AU - Callow, James A. AU - DeSimone, Joseph M. T2 - LANGMUIR AB - Herein we report the design of a photocurable amphiphilic co-network consisting of perfluoropolyether and poly(ethylene glycol) segments that display outstanding nonfouling characteristics with respect to spores of green fouling alga Ulva when cured under high humidity conditions. The analysis of contact angle hysteresis revealed that the poly(ethylene glycol) density at the surface was enhanced when cured under high humidity. The nonfouling behavior of nonbiocidal surfaces against marine fouling is rare because such surfaces usually reduce the adhesion of organisms rather than inhibit colonization. We propose that the resultant surface segregation of these materials induced by high humidity may be a promising strategy for achieving nonfouling materials, and such an approach is more important than simply concentrating poly(ethylene glycol) moieties at an interface because the low surface energy has been maintained in our work. DA - 2011/9/6/ PY - 2011/9/6/ DO - 10.1021/la202427z VL - 27 IS - 17 SP - 10365-10369 SN - 0743-7463 ER - TY - JOUR TI - Adsorption of PEO-PPO-PEO Triblock Copolymers with End-Capped Cationic Chains of Poly(2-dimethylaminoethyl methacrylate) AU - Liu, Xiaomeng AU - Vesterinen, Arja-Helena AU - Genzer, Jan AU - Seppala, Jukka V. AU - Rojas, Orlando J. T2 - LANGMUIR AB - We study the adsorption of a symmetric triblock copolymer of ethylene oxide, EO, and propylene oxide, PO, end-capped with quarternized poly(2-dimethylaminoethyl methacrylate), DMAEMA (DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24)). Light scattering and tensiometry are used to measure the relative size of the associated structures and surface excess at the air-liquid interface. The adsorbed amount, the amount of coupled water, and the viscoelasticity of the adsorbed polymer layer are measured on hydrophobic and hydrophilic surfaces (polypropylene, cellulose, and silica) by using quartz crystal microgravimetry (QCM) and surface plasmon resonance (SPR) at different ionic strengths and temperatures. The results of the experiments are compared with those obtained after adsorption of the uncharged precursor copolymer, without the cationic end-caps (EO(132)PO(50)EO(132)). DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24) possesses higher affinity with the negatively charged silica and cellulose surfaces while the uncharged copolymer adsorbs to a larger extent on polypropylene surfaces. In this latter case, adsorption increases with increasing solution ionic strength and temperature. Adsorption of EO(132)PO(50)EO(132) on silica surfaces has little effect on the water contact angle (WCA), while adsorption of DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24) increases the WCA of silica to 32°, indicating a large density of exposed PPO blocks upon adsorption. After adsorption of EO(132)PO(50)EO(132) and DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24) on PP, the WCA is reduced by ≈14° and ≈28°, respectively, due to the exposed hydrophilic EO and highly water-soluble DMAEMA segments on the surfaces. The extent of surface coverage at saturation at the polypropylene/liquid interfaces (≈31 and 40 nm(2)/molecule obtained by QCM and SPR, respectively) is much lower, as expected, when compared with results obtained at the air/liquid interface, where a tighter packing is observed. The percentage of water coupled to the adsorbed cationic polymer decreases with solution ionic strength. Overall, these observations are ascribed to the effects of electrostatic screening, polymer hydrodynamic size, and solvency. DA - 2011/8/16/ PY - 2011/8/16/ DO - 10.1021/la201596x VL - 27 IS - 16 SP - 9769-9780 SN - 0743-7463 ER - TY - JOUR TI - Sequential Vapor Infiltration of Metal Oxides into Sacrificial Polyester Fibers: Shape Replication and Controlled Porosity of Microporous/Mesoporous Oxide Monoliths AU - Gong, Bo AU - Peng, Qing AU - Jur, Jesse S. AU - Devine, Christina K. AU - Lee, Kyoungmi AU - Parsons, Gregory N. T2 - Chemistry of Materials AB - The preparation of microporous and mesoporous metal oxide materials continues to attract considerable attention, because of their possible use in chemical separations, catalyst support, chemical sensors, optical and electronic devices, energy storage, and solar cells. While many methods are known for the synthesis of porous materials, researchers continue to seek new methods to control pore size distribution and macroscale morphology. In this work, we show that sequential vapor infiltration (SVI) can yield shape-controlled micro/mesoporous materials with tunable pore size, using polyesters as a sacrificial template. The reaction proceeds by exposing polymer fiber templates to a controlled sequence of metal organic and co-reactant vapor exposure cycles in an atomic layer deposition (ALD) reactor. The precursors infuse sequentially and thereby distribute and react uniformly within the polymer, to yield an organic–inorganic hybrid material that retains the physical dimensions of the original polymer template. Subsequent calcination in air results in an inorganic microporous/mesoporous material that again retains the macroscopic physical shape of the starting polymer matrix. The microporous/mesoporous structure is confirmed by microscopy and nitrogen adsorption/desorption analysis, and the resulting pore size is controlled by the size of the starting polymer repeat unit and by the kinetics of the infiltration/annealing process steps. In situ infrared transmission and quartz crystal microbalance results confirm the chemical reaction mechanisms. The chemical transformation that occurs during SVI could be important for a range of applications that utilize well-defined porous nanostructures. DA - 2011/8/9/ PY - 2011/8/9/ DO - 10.1021/cm200694w VL - 23 IS - 15 SP - 3476-3485 J2 - Chem. Mater. LA - en OP - SN - 0897-4756 1520-5002 UR - http://dx.doi.org/10.1021/cm200694w DB - Crossref KW - porous material KW - metal oxide KW - aluminum oxide KW - titanium oxide KW - atomic layer deposition KW - vapor phase infiltration ER - TY - JOUR TI - Recent developments in nanostructured anode materials for rechargeable lithium-ion batteries AU - Ji, Liwen AU - Lin, Zhan AU - Alcoutlabi, Mataz AU - Zhang, Xiangwu T2 - ENERGY & ENVIRONMENTAL SCIENCE AB - In this paper, the use of nanostructured anode materials for rechargeable lithium-ion batteries (LIBs) is reviewed. Nanostructured materials such as nano-carbons, alloys, metal oxides, and metal sulfides/nitrides have been used as anodes for next-generation LIBs with high reversible capacity, fast power capability, good safety, and long cycle life. This is due to their relatively short mass and charge pathways, high transport rates of both lithium ions and electrons, and other extremely charming surface activities. In this review paper, the effect of the nanostructure on the electrochemical performance of these anodes is presented. Their synthesis processes, electrochemical properties, and electrode reaction mechanisms are also discussed. The major goals of this review are to give a broad overview of recent scientific researches and developments of anode materials using novel nanoscience and nanotechnology and to highlight new progresses in using these nanostructured materials to develop high-performance LIBs. Suggestions and outlooks on future research directions in this field are also given. DA - 2011/8// PY - 2011/8// DO - 10.1039/c0ee00699h VL - 4 IS - 8 SP - 2682-2699 SN - 1754-5706 UR - https://publons.com/publon/6540060/ ER - TY - JOUR TI - Pyridine Inhibitor Binding to the 4Fe-4S Protein A. aeolicus IspH (LytB): A HYSCORE Investigation AU - Wang, Weixue AU - Li, Jikun AU - Wang, Ke AU - Smirnova, Tatyana I. AU - Oldfield, Eric T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY AB - IspH is a 4Fe-4S protein that carries out an essential reduction step in isoprenoid biosynthesis. Using hyperfine sublevel correlation (HYSCORE) spectroscopy, we show that pyridine inhibitors of IspH directly bind to the unique fourth Fe in the 4Fe-4S cluster, opening up new routes to inhibitor design, of interest in the context of both anti-bacterial as well as anti-malarial drug discovery. DA - 2011/5/4/ PY - 2011/5/4/ DO - 10.1021/ja2008455 VL - 133 IS - 17 SP - 6525-6528 SN - 0002-7863 ER - TY - JOUR TI - Poly(2-hydroxyethyl methacrylate) for Enzyme Immobilization: Impact on Activity and Stability of Horseradish Peroxidase AU - Lane, Sarah M. AU - Kuang, Zhifeng AU - Yom, Jeannie AU - Arifuzzaman, Shafi AU - Genzer, Jan AU - Farmer, Barry AU - Naik, Rajesh AU - Vaia, Richard A. T2 - BIOMACROMOLECULES AB - On the basis of their versatile structure and chemistry as well as tunable mechanical properties, polymer brushes are well-suited as supports for enzyme immobilization. However, a robust surface design is hindered by an inadequate understanding of the impact on activity from the coupling motif and enzyme distribution within the brush. Herein, horseradish peroxidase C (HRP C, 44 kDa), chosen as a model enzyme, was immobilized covalently through its lysine residues on a N-hydroxysuccinimidyl carbonate-activated poly(2-hydroxyethyl methacrylate) (PHEMA) brush grafted chemically onto a flat impenetrable surface. Up to a monolayer coverage of HRP C is achieved, where most of the HRP C resides at or near the brush-air interface. Molecular modeling shows that lysines 232 and 241 are the most probable binding sites, leading to an orientation of the immobilized HRP C that does not block the active pocket of the enzyme. Michaelis-Menten kinetics of the immobilized HRP C indicated little change in the K(m) (Michaelis constant) but a large decrease in the V(max) (maximum substrate conversion rate) and a correspondingly large decrease in the k(cat) (overall catalytic rate). This indicates a loss in the percentage of active enzymes. Given the relatively ideal geometry of the HRPC-PHEMA brush, the loss of activity is most likely due to structural changes in the enzyme arising from either secondary constraints imposed by the connectivity of the N-hydroxysuccinimidyl carbonate linking moiety or nonspecific interactions between HRP C and DSC-PHEMA. Therefore, a general enzyme-brush coupling motif must optimize reactive group density to balance binding with neutrality of surroundings. DA - 2011/5// PY - 2011/5// DO - 10.1021/bm200173y VL - 12 IS - 5 SP - 1822-1830 SN - 1526-4602 ER - TY - JOUR TI - Liquid metals make microelectrodes AU - Dickey, M. T2 - Trac-Trends in Analytical Chemistry DA - 2011/// PY - 2011/// VL - 30 IS - 4 SP - VII- ER - TY - JOUR TI - Highly Stable Binding Proteins Derived from the Hyperthermophilic Sso7d Scaffold AU - Gera, Nimish AU - Hussain, Mahmud AU - Wright, Robert C. AU - Rao, Balaji M. T2 - JOURNAL OF MOLECULAR BIOLOGY AB - We have shown that highly stable binding proteins for a wide spectrum of targets can be generated through mutagenesis of the Sso7d protein from the hyperthermophilic archaeon Sulfolobus solfataricus. Sso7d is a small (∼ 7 kDa, 63 amino acids) DNA-binding protein that lacks cysteine residues and has a melting temperature of nearly 100 °C. We generated a library of 108 Sso7d mutants by randomizing 10 amino acid residues on the DNA-binding surface of Sso7d, using yeast surface display. Binding proteins for a diverse set of model targets could be isolated from this library; our chosen targets included a small organic molecule (fluorescein), a 12 amino acid peptide fragment from the C-terminus of β-catenin, the model proteins hen egg lysozyme and streptavidin, and immunoglobulins from chicken and mouse. Without the application of any affinity maturation strategy, the binding proteins isolated had equilibrium dissociation constants in the nanomolar to micromolar range. Further, Sso7d-derived binding proteins could discriminate between closely related immunoglobulins. Mutant proteins based on Sso7d were expressed at high yields in the Escherichia coli cytoplasm. Despite extensive mutagenesis, Sso7d mutants have high thermal stability; five of six mutants analyzed have melting temperatures > 89 °C. They are also resistant to chemical denaturation by guanidine hydrochloride and retain their secondary structure after extended incubation at extreme pH values. Because of their favorable properties, such as ease of recombinant expression, and high thermal, chemical and pH stability, Sso7d-derived binding proteins will have wide applicability in several areas of biotechnology and medicine. DA - 2011/6/17/ PY - 2011/6/17/ DO - 10.1016/j.jmb.2011.04.020 VL - 409 IS - 4 SP - 601-616 SN - 0022-2836 KW - hyperthermophilic protein scaffolds KW - yeast surface display KW - protein engineering KW - stability KW - alternate scaffold ER - TY - JOUR TI - Encapsulation Efficiency and Micellar Structure of Solute-Carrying Block Copolymer Nanoparticles AU - Woodhead, Jeffrey L. AU - Hall, Carol K. T2 - MACROMOLECULES AB - We use discontinuous molecular dynamics (DMD) computer simulation to investigate the encapsulation efficiency and micellar structure of solute-carrying block copolymer nanoparticles as a function of packing fraction, polymer volume fraction, solute mole fraction, and the interaction parameters between the hydrophobic head blocks and between the head and the solute. The encapsulation efficiency increases with increasing polymer volume fraction and packing fraction but decreases with increasing head–head interaction strength. The latter is due to an increased tendency for the solute to remain on the micelle surface. We compared two different nanoparticle assembly methods: one in which the solute and copolymer coassociate and the other in which the copolymer micelle is formed before the introduction of solute. The assembly method does not affect the encapsulation efficiency but does affect the solute uptake kinetics. Both head–solute interaction strength and head–head interaction strength affect the density profile of the micelles; increases in the former cause the solute to distribute more evenly throughout the micelle, while increases in the latter cause the solute to concentrate further from the center of the micelle. We explain our results in the context of a model of drug insertion into micelles formulated by Kumar and Prud’homme; as conditions become more conducive to micelle formation, a stronger energy barrier to solute insertion forms which in turn decreases the encapsulation efficiency of the system. DA - 2011/7/12/ PY - 2011/7/12/ DO - 10.1021/ma102938g VL - 44 IS - 13 SP - 5443-5451 SN - 0024-9297 ER - TY - JOUR TI - Electrospun Carbon-Tin Oxide Composite Nanofibers for Use as Lithium Ion Battery Anodes AU - Bonino, Christopher A. AU - Ji, Liwen AU - Lin, Zhan AU - Toprakci, Ozan AU - Zhang, Xiangwu AU - Khan, Saad A. T2 - ACS APPLIED MATERIALS & INTERFACES AB - Composite carbon–tin oxide (C-SnO2) nanofibers are prepared by two methods and evaluated as anodes in lithium-ion battery half cells. Such an approach complements the long cycle life of carbon with the high lithium storage capacity of tin oxide. In addition, the high surface-to-volume ratio of the nanofibers improves the accessibility for lithium intercalation as compared to graphite-based anodes, while eliminating the need for binders or conductive additives. The composite nanofibrous anodes have first discharge capacities of 788 mAh g–1 at 50 mA g–1 current density, which are greater than pure carbon nanofiber anodes, as well as the theoretical capacity of graphite (372 mAh g–1), the traditional anode material. In the first protocol to fabricate the C-SnO2 composites, tin sulfate is directly incorporated within polyacrylonitrile (PAN) nanofibers by electrospinning. During a thermal treatment the tin salt is converted to tin oxide and the polymer is carbonized, yielding carbon-SnO2 nanofibers. In the second approach, we soak the nanofiber mats in tin sulfate solutions prior to the final thermal treatment, thereby loading the outer surfaces with SnO2 nanoparticles and raising the tin content from 1.9 to 8.6 wt %. Energy-dispersive spectroscopy and X-ray diffraction analyses confirm the formation of conversion of tin sulfate to tin oxide. Furthermore, analysis with Raman spectroscopy reveals that the additional salt soak treatment from the second fabrication approach increases in the disorder of the carbon structure, as compared to the first approach. We also discuss the performance of our C-SnO2 compared with its theoretical capacity and other nanofiber electrode composites previously reported in the literature. DA - 2011/7// PY - 2011/7// DO - 10.1021/am2004015 VL - 3 IS - 7 SP - 2534-2542 SN - 1944-8252 UR - https://publons.com/publon/674395/ KW - composite nanofibers KW - electrospinning KW - lithium-ion battery KW - tin oxide KW - anode ER - TY - JOUR TI - Effects of UV Exposure and Initiator Concentration on the Spatial Variation of Poly(glycidyl methacrylate) Grafts on Nonwoven Fabrics AU - Zheng, Yong AU - Gurgel, Patrick V. AU - Carbonell, Ruben G. T2 - INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH AB - This paper describes the spatial uniformity of grafted layers of poly(glycydyl methacrylate) on the fibers of polypropylene nonwoven fabrics, and how they depend on the UV pretreatment step, the adsorption of initiator (benzophenone) to the fiber surface, and the UV grafting step. UV light transmission inside the nonwoven fabrics was measured to determine the effect of light intensity variations during the pretreatment and grafting steps. The light intensity decay depends on the pore size of the fabric and the presence of solvents in the nonwoven fabric. The adsorption of benzophenone to the fiber surface is lower in regions of low light intensity, resulting in a spatial variation due to the UV pretreatment. The presence of solvents tends to reduce light intensity decay during the grafting step. The results of this paper indicate how to avoid spatial nonuniformities during grafting by controlling the reaction conditions. DA - 2011/5/18/ PY - 2011/5/18/ DO - 10.1021/ie1021333 VL - 50 IS - 10 SP - 6115-6123 SN - 0888-5885 ER - TY - JOUR TI - Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers prepared by atmospheric plasma treatment and electrospinning AU - Shi, Quan AU - Vitchuli, Narendiran AU - Nowak, Joshua AU - Caldwell, Jane M. AU - Breidt, Frederick AU - Bourham, Mohamed AU - Zhang, Xiangwu AU - McCord, Marian T2 - EUROPEAN POLYMER JOURNAL AB - Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the AgNO3 precursor in pre-electrospinning solutions into metallic silver nanoparticles, followed by electrospinning into continuous and smooth nanofibers with Ag nanoparticles embedded in the matrix. SEM, TEM, and EDX spectra were used to study the structure and surface elemental composition of the nanofibers. Silver nanoparticles, with diameters ranging between 3 and 6 nm, were found to be uniformly dispersed in the nanofiber matrix. The Ag/PAN nanofibers exhibited slow and long-lasting silver ion release, which provided robust antibacterial activity against both Gram-positive Bacillus cereus and Gram-negative Escherichia coli microorganisms. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.eurpolymj.2011.04.002 VL - 47 IS - 7 SP - 1402-1409 SN - 1873-1945 UR - https://publons.com/publon/3117884/ KW - Atmospheric plasma KW - Electrospinning KW - Nanofibers KW - Ag nanoparticles KW - Antibacterial activity ER - TY - JOUR TI - Combustion chemistry and fuel-nitrogen conversion in a laminar premixed flame of morpholine as a model biofuel AU - Lucassen, Arnas AU - Labbe, Nicole AU - Westmoreland, Phillip R. AU - Kohse-Höinghaus, Katharina T2 - Combustion and Flame AB - The present study has been motivated by the need to understand and predict fuel-nitrogen conversion in the combustion of biomass-derived fuels. Within that broader context, an earlier related publication (Lucassen et al., Proc. Combust. Inst. 32 (2009) 1269–1276) has investigated morpholine (C4H9NO, 1-oxa-4-aza-cyclohexane) as a model oxygen- and nitrogen-containing biofuel, and species identification was presented for a slightly fuel-rich Φ = 1.3 (C/O = 0.41) laminar premixed morpholine-oxygen-argon flame at 40 mbar. To attempt a more detailed insight into the flame structure and combustion mechanism, the present contribution has now combined photoionization (PI) and electron ionization (EI) molecular-beam mass spectrometry (MBMS) to determine absolute mole-fraction profiles of numerous major and intermediate species with up to 6 heavy atoms. In general, PI-MBMS and EI-MBMS results were found in good agreement. The results reveal formation of a number of intermediates that may contribute to harmful emissions, including aldehydes and several nitrogen-containing compounds in percent-level concentrations. Both NH3 and HCN pathways are seen to contribute to NO formation. To identify reaction pathways for this detailed experimental analysis, development of a flame model was started, considering a combustion mechanism for cyclohexane and analogous fuel-breakdown reactions for morpholine by addition of necessary thermodynamic, transport and kinetic parameters. The present model captures relevant features of the morpholine flame quite well, including HCN, N2, and NO, and it can serve as a nucleus for further development of detailed combustion models for fuel-nitrogen conversion from model biofuel compounds. DA - 2011/9// PY - 2011/9// DO - 10.1016/j.combustflame.2011.02.010 VL - 158 IS - 9 SP - 1647-1666 J2 - Combustion and Flame LA - en OP - SN - 0010-2180 UR - http://dx.doi.org/10.1016/j.combustflame.2011.02.010 DB - Crossref KW - Fuel-nitrogen conversion KW - Biofuel KW - Premixed flame KW - Molecular-beam mass spectrometry ER - TY - JOUR TI - Block copolymer self-organization vs. interfacial modification in bilayered thin-film laminates AU - Gozen, Arif O. AU - Zhou, Jiajia AU - Roskov, Kristen E. AU - Shi, An-Chang AU - Genzer, Jan AU - Spontak, Richard J. T2 - SOFT MATTER AB - Block copolymers remain one of the most extensively studied and utilized classes of macromolecules due to their extraordinary abilities to (i) self-assemble spontaneously into a wide variety of soft nanostructures and (ii) reduce the interfacial tension between, and thus compatibilize, immiscible polymer pairs. In bilayered thin-film laminates of immiscible homopolymers, block copolymers are similarly envisaged to stabilize such laminates. Contrary to intuition, we demonstrate that highly asymmetric block copolymers can conversely destabilize a laminate, as discerned from macroscopic dewetting behavior, due to dynamic competition between copolymer self-organization away from and enrichment at the bilayer interface. The mechanism of this counterintuitive destabilization is interrogated through complementary analysis of laminates containing mixtures of stabilizing/destabilizing diblock copolymers and time-dependent Ginzburg–Landau computer simulations. This combination of experiments and simulations reveals a systematic progression of supramolecular-level events that establish the relative importance of molecular aggregation and lateral interfacial structuring in a highly nonequilibrium environment. DA - 2011/// PY - 2011/// DO - 10.1039/c0sm01169j VL - 7 IS - 7 SP - 3268-3272 SN - 1744-6848 ER - TY - JOUR TI - Adsorption and Association of a Symmetric PEO-PPO-PEO Triblock Copolymer on Polypropylene, Polyethylene, and Cellulose Surfaces AU - Li, Yan AU - Liu, Hongyi AU - Song, Junlong AU - Rojas, Orlando J. AU - Hinestroza, Juan P. T2 - ACS APPLIED MATERIALS & INTERFACES AB - The association of a symmetric polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO19–PPO29–PEO19) triblock copolymer adsorbed from aqueous solutions onto polypropylene (PP), polyethylene (PE), and cellulose surfaces was probed using Atomic Force Microscopy (AFM). Significant morphological differences between the polyolefin substrates (PP and PE) and the cellulose surfaces were observed after immersion of the films in the PEO19–PPO29–PEO19 solutions. When the samples were scanned, while immersed in solutions of the triblock copolymer, it was revealed that the structures adsorbed on the polyolefin surfaces were smoothed by the adsorbed PEO19–PPO29–PEO19. In contrast, those structures on the hydrophilic cellulose surfaces were sharpened. These observations were related to the roughness of the substrate and the energy of interaction between the surfaces and the PEO and PPO polymer segments. The interaction energy between each of the blocks and the surface was calculated using molecular dynamics simulations. It is speculated that the associative structures amply reported in aqueous solution at concentrations above the critical micelle concentration, CMC, are not necessarily preserved upon adsorption; instead, it appears that molecular arrangements of the anchor-buoy type and hemimicelles prevail. The reported data suggests that the roughness of the surface, as well as its degree of hydrophobicity, have a large influence on the nature of the resulting adsorbed layer. The reported observations are valuable in explaining the behavior of finishing additives and lubricants commonly used in textile and fiber processing, as well as the effect of the morphology of the boundary layers on friction and wear, especially in the case of symmetric triblock copolymers, which are commonly used as antifriction, antiwear additives. DA - 2011/7// PY - 2011/7// DO - 10.1021/am200264r VL - 3 IS - 7 SP - 2349-2357 SN - 1944-8244 ER - TY - JOUR TI - VapC6, a ribonucleolytic toxin regulates thermophilicity in the crenarchaeote Sulfolobus solfataricus AU - Maezato, Yukari AU - Daugherty, Amanda AU - Dana, Karl AU - Soo, Edith AU - Cooper, Charlotte AU - Tachdjian, Sabrina AU - Kelly, Robert M. AU - Blum, Paul T2 - RNA AB - The phylum Crenarchaeota includes hyperthermophilic micro-organisms subjected to dynamic thermal conditions. Previous transcriptomic studies of Sulfolobus solfataricus identified vapBC6 as a heat-shock (HS)-inducible member of the Vap toxin-antitoxin gene family. In this study, the inactivation of the vapBC6 operon by targeted gene disruption produced two recessive phenotypes related to fitness, HS sensitivity and a heat-dependent reduction in the rate of growth. In-frame vapBC6 deletion mutants were analyzed to examine the respective roles of each protein. Since vapB6 transcript abundance was elevated in the vapC6 deletion, the VapC6 toxin appears to regulate abundance of its cognate antitoxin. In contrast, vapC6 transcript abundance was reduced in the vapB6 deletion. A putative intergenic terminator may underlie these observations by coordinating vapBC6 expression. As predicted by structural modeling, recombinant VapC6 produced using chaperone cosynthesis exhibited heat-dependent ribonucleolytic activity toward S. solfataricus total RNA. This activity could be blocked by addition of preheated recombinant VapB6. In vivo transcript targets were identified by assessing the relative expression of genes that naturally respond to thermal stress in VapBC6-deficient cells. Preferential increases were observed for dppB-1 and tetR, and preferential decreases were observed for rpoD and eIF2 gamma. Specific VapC6 ribonucleolytic action could also be demonstrated in vitro toward RNAs whose expression increased in the VapBC6-deficient strain during heat shock. These findings provide a biochemical mechanism and identify cellular targets underlying VapBC6-mediated control over microbial growth and survival at temperature extremes. DA - 2011/7// PY - 2011/7// DO - 10.1261/rna.2679911 VL - 17 IS - 7 SP - 1381-1392 SN - 1469-9001 KW - antitoxin KW - RNA degradation KW - heat shock KW - archaea KW - transcription ER - TY - JOUR TI - Polystyrene/Decahydronaphthalene/Propane Phase Equilibria and Polymer Conformation Properties from Intrinsic Viscosities AU - Cain, Nathaniel AU - Haywood, Alexander AU - Roberts, George AU - Kiserow, Douglas AU - Carbonell, Ruben T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract The influence of dissolved propane (up to 31.2 wt %) on the phase equilibria of 5 wt % polystyrene (PS) dissolved in 66/34 wt % trans/cis ‐decahydronaphthalene (DHN) was measured over the temperature range of 323–423 K. A suitable temperature, pressure, and propane composition operating space was defined to measure intrinsic viscosities of a single fluid phase. Intrinsic viscosities of PS in cosolvent mixtures of propane and trans/cis ‐DHN were measured between 323 and 423 K and between 70 and 208 bar. The addition of propane to the isomeric mixture of DHN resulted in a decreased solvent quality for PS, causing a contraction of the PS coil. The most dramatic decrease in solvent quality with the addition of propane occurred at 323 K and 70 bar with approximately a 36% reduction in the viscometric radius with the addition of 45 mol % propane to DHN. At 423 K, the solvent quality was less sensitive to the addition of propane and only a 13% reduction in the viscometric radius was observed at 70 bar and 45 mol % propane in DHN. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 DA - 2011/8/1/ PY - 2011/8/1/ DO - 10.1002/polb.22282 VL - 49 IS - 15 SP - 1093-1100 SN - 0887-6266 KW - conformational analysis KW - decahydronaphthalene KW - intrinsic viscosity KW - miscibility KW - phase behavior KW - phase diagrams KW - phase separation KW - polystyrene KW - viscosity ER - TY - JOUR TI - Performance of hexamer peptide ligands for affinity purification of immunoglobulin G from commercial cell culture media AU - Naik, A. D. AU - Menegatti, S. AU - Gurgel, P. V. AU - Carbonell, R. G. T2 - Journal of Chromatography A AB - Previous work has reported on the identification and characterization of the hexapeptide ligands HWRGWV, HYFKFD, and HFRRHL for the affinity capture of IgG through specific binding to its Fc fragment. This paper addresses issues related to the successful application of these ligands, on a commercial methacrylate chromatographic resin, for the purification of IgG from mammalian cell culture fluids. The concentrations of sodium chloride and sodium caprylate in the binding buffer were optimized to maximize the purity and yield of IgG upon elution. Screening of several regeneration conditions found that either 2 M guanidine–HCl or a combination of 0.85% phosphoric acid followed by 2 M urea resulted in complete recovery of the IgG adsorption capacity and that the column could be reused over many cycles. The hexapeptide ligands were used for the purification of humanized and chimeric monoclonal antibodies from two commercial CHO cell culture fluids. The chimeric MAb of IgG1 subclass was purified using the HWRGWV resin whereas the humanized MAb of IgG4 subclass was purified using the HWRGWV, HYFKFD and HFRRHL resins. The purities and yields obtained for both the MAbs were found to be higher than 94% and 85% respectively. These results compare well with the yields and purities obtained using Protein G columns. The residual DNA and host cell protein reduction obtained by the HWRGWV resin was in the range of 4 log reduction value (LRV) and 2 LRV respectively, comparable to those reported for Protein A resins. The dynamic binding capacity of all three peptide resins for the humanized monoclonal antibody was in the range of 20 mg/mL. DA - 2011/4/1/ PY - 2011/4/1/ DO - 10.1016/j.chroma.2010.11.071 VL - 1218 IS - 13 SP - 1691–1700 KW - Hexapeptide ligand KW - IgG purification KW - Monoclonal antibody KW - Affinity chromatography KW - Regeneration ER - TY - JOUR TI - Parameter estimation and capacity fade analysis of lithium-ion batteries using reformulated models AU - Ramadesigan, V. AU - Chen, K. J. AU - Burns, N. A. AU - Boovaragavan, V. AU - Braatz, R. D. AU - Subramanian, V. R. T2 - Journal of the Electrochemical Society DA - 2011/// PY - 2011/// VL - 158 IS - 9 SP - A1048-1054 ER - TY - JOUR TI - Kinetic modeling study of ethanol and dimethyl ether addition to premixed low-pressure propene–oxygen–argon flames AU - Frassoldati, Alessio AU - Faravelli, Tiziano AU - Ranzi, Eliseo AU - Kohse-Höinghaus, Katharina AU - Westmoreland, Phillip R. T2 - Combustion and Flame AB - The chemical composition of flames of mixed hydrocarbon–oxygenate fuels was examined systematically for a series of laminar, premixed low-pressure propene–oxygen–argon flames blended with ethanol or dimethyl ether (DME). All flames were established at a carbon-to-oxygen ratio of C/O = 0.5 at 40 mbar. Propene was replaced incrementally by either additive, so that the entire range from pure propene to pure ethanol or pure DME was accessible. Experimental results have been reported previously (J. Wang et al., J. Chem. Phys. A 112 (2008) 9255–9265), including temperature profiles measured with laser-induced fluorescence (LIF) and quantitative mole fraction profiles for a large number of species obtained from molecular-beam mass spectrometry (MBMS), using electron ionization (EI) and vacuum-ultraviolet (VUV) photoionization (PI). The effects of oxygenate addition to the propene base flame were seen to result in interesting differences, especially regarding trends to form aldehydes. The entire flame series is now analyzed with a comprehensive kinetic model that combines the chemistries of propene, ethanol, and DME combustion. The flames of pure fuels are also compared with the predictions of different detailed mechanisms taken from the literature. Quantitative comparison of C1- to C6-species from this model with the measurements is provided. Major trends of propene replacement by the oxygenates are reproduced in quantitative agreement with the experiments, enabling a more detailed understanding of the combined reaction sequences in such fuel blends. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.combustflame.2010.12.015 VL - 158 IS - 7 SP - 1264-1276 J2 - Combustion and Flame LA - en OP - SN - 0010-2180 UR - http://dx.doi.org/10.1016/j.combustflame.2010.12.015 DB - Crossref KW - Modeling KW - Oxygenate fuel blends KW - Ethanol combustion KW - Dimethyl ether combustion KW - Propene combustion ER - TY - JOUR TI - Fabrication and characterization of LATP/PAN composite fiber-based lithium-ion battery separators AU - Liang, Yinzheng AU - Lin, Zhan AU - Qiu, Yiping AU - Zhang, Xiangwu T2 - ELECTROCHIMICA ACTA AB - Lithium aluminum titanium phosphate (LATP)/polyacrylonitrile (PAN) composite fiber-based membranes were prepared by electrospinning dispersions of LATP particles in PAN solutions. The electrolyte uptakes of the electrospun LATP/PAN composite fiber-based membranes were measured and the results showed that the electrolyte uptake increased as the LATP content increased. The lithium ion conductivity, the electrochemical oxidation limit and the interface resistance of liquid electrolyte-soaked electrospun LATP/PAN composite fiber-based membranes were also measured and it was found that as the LATP content increased, the electrospun LATP/PAN composite fiber-based membranes had higher lithium ion conductivity, better electrochemical stability, and lower interfacial resistance with lithium electrode. Additionally, lithium//1 M LiPF6/EC/EMC//lithium iron phosphate cells using LATP/PAN composite fiber-based membranes as the separator demonstrated high charge/discharge capacity and good cycle performance. DA - 2011/7/15/ PY - 2011/7/15/ DO - 10.1016/j.electacta.2011.05.007 VL - 56 IS - 18 SP - 6474-6480 SN - 0013-4686 UR - https://publons.com/publon/6540061/ KW - Lithium-ion batteries KW - Separators KW - Glass-ceramics KW - LATP KW - Electrospinning KW - Sol-gel ER - TY - JOUR TI - Encapsulation and Chemical Resistance of Electrospun Nylon Nanofibers Coated Using Integrated Atomic and Molecular Layer Deposition AU - Oldham, Christopher J. AU - Gong, Bo AU - Spagnola, Joseph C. AU - Jur, Jesse S. AU - Senecal, Kris J. AU - Godfrey, Thomas A. AU - Parsons, Gregory N. T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - Nanofibers formed by electrospinning provide very large surface areas which can enhance material performance in filtration and product separation. In this work, we explore atomic layer deposition (ALD) as a means to coat and protect electrospun nylon-6 nanofibers. Exposing nylon to trimethyl aluminum (TMA) during ALD of aluminum oxide results in significant fiber degradation. Protecting fibers with a bilayer of ALD ZnO and an organic-inorganic hybrid polymer by molecular layer deposition maintains the shape of the original nanofibers, but chemical modification is still detected. These coating processes may help enable nanofibers with stable physical properties under chemical exposure. DA - 2011/// PY - 2011/// DO - 10.1149/1.3609046 VL - 158 IS - 9 SP - D549-D556 SN - 1945-7111 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000293175600039&KeyUID=WOS:000293175600039 ER - TY - JOUR TI - Dodging Drug-Resistant Cancer with Diamonds AU - Merkel, Timothy J. AU - DeSimone, Joseph M. T2 - SCIENCE TRANSLATIONAL MEDICINE AB - Nanodiamond-drug conjugates show antitumor activity in mouse models of chemoresistant breast and liver cancer. DA - 2011/3/9/ PY - 2011/3/9/ DO - 10.1126/scitranslmed.3002137 VL - 3 IS - 73 SP - SN - 1946-6242 ER - TY - JOUR TI - Cloud Point Suppression in Dilute Solutions of Model Gradient Copolymers with Prespecified Composition Profiles AU - Gallow, Keith C. AU - Jhon, Young K. AU - Tang, Wei AU - Genzer, Jan AU - Loo, Yueh-Lin T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract Gradient copolymers of 2‐hydroxyethyl methacrylate (HEMA) and 2‐(dimethylamino)ethyl methacrylate (DMAEMA) having prescribed linear, parabolic, and hyperbolic composition profiles were synthesized with the guidance of a numerical model that determines the instantaneous comonomer feed rate. These materials exhibit low polydispersity indices (<1.1); the evolution of the overall DMAEMA content and the absolute molecular weight of the copolymers are all in good agreement with the quantities predicted by our model. Compared to random copolymers of HEMA and DMAEMA, the cloud points of dilute buffered aqueous solutions of gradient copolymers decrease with increasing gradient strength; where the gradient strength is defined as the largest difference in the instantaneous composition along the copolymer. The temperature range over which the solutions transition from transparent to turbid also broadens significantly with increasing gradient strength. Both observations suggest the onset of transition to be dictated by the least soluble ends of the polymer chains. These correlations point to the importance of monomer sequence distribution in determining the macroscopic physical properties of copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 DA - 2011/5/1/ PY - 2011/5/1/ DO - 10.1002/polb.22226 VL - 49 IS - 9 SP - 629-637 SN - 1099-0488 KW - atom transfer radical polymerization KW - cloud point KW - composition profile KW - dimethylaminoethyl methacrylate KW - dilute aqueous solutions KW - gradient copolymers KW - gradient strength KW - hydroxyethyl methacrylate KW - monomer sequence distribution ER - TY - JOUR TI - A novel alpha-d-galactosynthase from Thermotoga maritima converts beta-d-galactopyranosyl azide to alpha-galacto-oligosaccharides AU - Cobucci-Ponzano, Beatrice AU - Zorzetti, Carmela AU - Strazzulli, Andrea AU - Carillo, Sara AU - Bedini, Emiliano AU - Corsaro, Maria Michela AU - Comfort, Donald A. AU - Kelly, Robert M. AU - Rossi, Mose AU - Moracci, Marco T2 - GLYCOBIOLOGY AB - The large-scale production of oligosaccharides is a daunting task, hampering the study of the role of glycans in vivo and the testing of the efficacy of novel glycan-based drugs. Glycosynthases, mutated glycosidases that synthesize oligosaccharides in high yields, are becoming important chemo-enzymatic tools for the production of oligosaccharides. However, while β-glycosynthase can be produced with a rather well-established technology, examples of α-glycosynthases are thus far limited only to enzymes from glycoside hydrolase 29 (GH29), GH31 and GH95 families. α-l-Fucosynthases from GH29 use convenient glycosyl azide derivatives as a strategic alternative to glycosyl fluoride donors. However, the general applicability of this method to other α-glycosynthases is not trivial and remains to be confirmed. Here, β-d-galactopyranosyl azide was converted to α-galacto-oligosaccharides with good yields and high regioselectivity, catalyzed by a novel α-galactosynthase based on the GH36 α-galactosidase from the hyperthermophilic bacterium Thermotoga maritima. These results open a new avenue to the practical synthesis of biologically interesting α-galacto-oligosaccharides and demonstrate more widespread use of β-glycosyl-azide as donors, confirming their utility to expand the repertoire of glycosynthases. DA - 2011/4// PY - 2011/4// DO - 10.1093/glycob/cwq177 VL - 21 IS - 4 SP - 448-456 SN - 1460-2423 KW - alpha-galacto-oligosaccharides KW - glycosynthase KW - alpha-gal epitope KW - carbohydrate synthesis KW - protein engineering ER - TY - JOUR TI - Surface Interaction Forces of Cellulose Nanocrystals Grafted with Thermoresponsive Polymer Brushes AU - Zoppe, Justin O. AU - Osterberg, Monika AU - Venditti, Richard A. AU - Laine, Janne AU - Rojas, Orlando J. T2 - BIOMACROMOLECULES AB - The colloidal stability and thermoresponsive behavior of poly(N-isopropylacrylamide) brushes grafted from cellulose nanocrystals (CNCs) of varying graft densities and molecular weights was investigated. Indication of the grafted polymer brushes was obtained after AFM imaging of CNCs adsorbed on silica. Also, aggregation of the nanoparticles carrying grafts of high degree of polymerization was observed. The responsiveness of grafted CNCs in aqueous dispersions and as an ultrathin film was evaluated by using light scattering, viscosimetry, and colloidal probe microscopy (CPM). Light transmittance measurements showed temperature-dependent aggregation originating from the different graft densities and molecular weights. The lower critical solution temperature (LCST) of grafted poly(NiPAAm) brushes was found to decrease with the ionic strength, as is the case for free poly(NiPAAm) in aqueous solution. Thermal responsive behavior of grafted CNCs in aqueous dispersions was observed by a sharp increase in dispersion viscosity as the temperature approached the LCST. CPM in liquid media for asymmetric systems consisting of ultrathin films of CNCs and a colloidal silica probe showed the distinctive effects of the grafted polymer brushes on interaction and adhesive forces. The origin of such forces was found to be mainly electrostatic and steric in the case of bare and grafted CNCs, respectively. A decrease in the onset of attractive and adhesion forces of grafted CNCs films were observed with the ionic strength of the aqueous solution. The decreased mobility of polymer brushes upon partial collapse and decreased availability of hydrogen bonding sites with higher electrolyte concentration were hypothesized as the main reasons for the less prominent polymer bridging between interacting surfaces. DA - 2011/7// PY - 2011/7// DO - 10.1021/bm200551p VL - 12 IS - 7 SP - 2788-2796 SN - 1525-7797 ER - TY - JOUR TI - Starch Self-Processing in Transgenic Sweet Potato Roots Expressing a Hyperthermophilic alpha-Amylase AU - Santa-Maria, Monica C. AU - Yencho, Craig G. AU - Haigler, Candace H. AU - Thompson, William F. AU - Kelly, Robert M. AU - Sosinski, Bryon T2 - BIOTECHNOLOGY PROGRESS AB - Abstract Sweet potato is a major crop in the southeastern United States, which requires few inputs and grows well on marginal land. It accumulates large quantities of starch in the storage roots and has been shown to give comparable or superior ethanol yields to corn per cultivated acre in the southeast. Starch conversion to fermentable sugars (i.e., for ethanol production) is carried out at high temperatures and requires the action of thermostable and thermoactive amylolytic enzymes. These enzymes are added to the starch mixture impacting overall process economics. To address this shortcoming, the gene encoding a hyperthermophilic α‐amylase from Thermotoga maritima was cloned and expressed in transgenic sweet potato, generated by Agrobacterium tumefaciens‐mediated transformation, to create a plant with the ability to self‐process starch. No significant enzyme activity could be detected below 40°C, but starch in the transgenic sweet potato storage roots was readily hydrolyzed at 80°C. The transgene did not affect normal storage root formation. The results presented here demonstrate that engineering plants with hyperthermophilic glycoside hydrolases can facilitate cost effective starch conversion to fermentable sugars. Furthermore, the use of sweet potato as an alternative near‐term energy crop should be considered. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011 DA - 2011/// PY - 2011/// DO - 10.1002/btpr.573 VL - 27 IS - 2 SP - 351-359 SN - 1520-6033 KW - hyperthermophilic enzymes KW - starch conversion KW - transgenic plants KW - sweet potato KW - biofuels ER - TY - JOUR TI - Role of stringlike, supramolecular assemblies in reentrant supernematic liquid crystals AU - Mazza, Marco G. AU - Greschek, Manuel AU - Valiullin, Rustem AU - Schoen, Martin T2 - PHYSICAL REVIEW E AB - Using a combination of isothermal-isobaric Monte Carlo and microcanonical molecular dynamics we investigate the relation between structure and self-diffusion in various phases of a model liquid crystal using the Gay-Berne-Kihara potential. These molecules are confined to a mesoscopic slit-pore with atomically smooth substrate surfaces. As reported recently [see M. G. Mazza {\em et al.}, Phys. Rev. Lett. {\bf 105}, 227802 (2010)], a reentrant nematic (RN) phase may form at sufficiently high pressures/densities. This phase is characterized by a high degree of nematic order and a substantially enhanced self-diffusivity in the direction of the director $\hat{\bm{n}}$ which exceeds that of the lower-density nematic and an intermittent smectic A phase by about an order of magnitude. Here we demonstrate that the unique transport behavior in the RN phase may be linked to a confinement-induced packing effect which causes the formation of supramolecular, string-like conformations. The strings consist of several individual molecules that are capable of travelling in the direction of $\hat{\bm{n}}$ as individual "trains" consisting of chains of molecular "cars". Individual trains run in parallel and may pass each other at sufficiently high pressures. DA - 2011/5/13/ PY - 2011/5/13/ DO - 10.1103/physreve.83.051704 VL - 83 IS - 5 SP - SN - 1550-2376 ER - TY - JOUR TI - Poly(vinylmethylsiloxane) Elastomer Networks as Functional Materials for Cell Adhesion and Migration Studies AU - Ahmed, Shoeb AU - Yang, Hyun-kwan AU - Ozcam, Ali E. AU - Efimenko, Kirill AU - Weiger, Michael C. AU - Genzer, Jan AU - Haugh, Jason M. T2 - BIOMACROMOLECULES AB - Cell migration is central to physiological responses to injury and infection and in the design of biomaterial implants. The ability to tune the properties of adhesive materials and relate those properties in a quantitative way to the dynamics of intracellular processes remains a definite challenge in the manipulation of cell migration. Here, we propose the use of poly(vinylmethylsiloxane) (PVMS) networks as novel substrata for cell adhesion and migration. These materials offer the ability to tune independently chemical functionality and elastic modulus. Importantly, PVMS networks are compatible with total internal reflection fluorescence (TIRF) microscopy, which is ideal for interrogating the cell-substratum interface; this latter characteristic presents a distinct advantage over polyacrylamide gels and other materials that swell with water. To demonstrate these capabilities, adhesive peptides containing the arginyl-glycyl-aspartic acid (RGD) tripeptide motif were successfully grafted to the surface of PVMS network using a carboxyl-terminated thiol as a linker. Peptide-specific adhesion, spreading, and random migration of NIH 3T3 mouse fibroblasts were characterized. These experiments show that a peptide containing the synergy sequence of fibronectin (PHSRN) in addition to RGD promotes more productive cell migration without markedly enhancing cell adhesion strength. Using TIRF microscopy, the dynamics of signal transduction through the phosphoinositide 3-kinase pathway were monitored in cells as they migrated on peptide-grafted PVMS surfaces. This approach offers a promising avenue for studies of directed migration and mechanotransduction at the level of intracellular processes. DA - 2011/4// PY - 2011/4// DO - 10.1021/bm101549y VL - 12 IS - 4 SP - 1265-1271 SN - 1526-4602 ER - TY - JOUR TI - Photochromic materials with tunable color and mechanical flexibility AU - Yang, Hyun-Kwan AU - Ozcam, A. Evren AU - Efimenko, Kirill AU - Genzer, Jan T2 - SOFT MATTER AB - Florescence switches based on photochromic compounds have been fabricated previously and identified as potential candidates for information technology. Recently, optically responsive materials with tunable color have been prepared by dissolving photochromic compounds, such as spiropyran (SP), into solutions of various pH or embedding them into sol–gel matrices with adjusted chemical compositions. Here we report on fabricating flexible rubbers with tunable color by embedding SP molecules inside silicone elastomer networks (SENs) based on poly(vinylmethylsiloxane) (PVMS). SP-containing PVMS networks have been further modified either physically by exposing them to ultraviolet/ozone treatment or chemically by attaching functional thiols to the vinyl bonds in PVMS via UV-activated thiol–ene addition. The color hue of the SP–PVMS SENs after exposing to UV light depends on either the UVO dose or the chemical end-functionality of the thiol modifier, respectively. We also present simple methodologies enabling patterning regions in SP-doped SENs with various shapes and colors. DA - 2011/// PY - 2011/// DO - 10.1039/c0sm00928h VL - 7 IS - 8 SP - 3766-3774 SN - 1744-683X ER - TY - JOUR TI - Novel Platforms for Vascular Carriers with Controlled Geometry AU - Pillai, Jonathan D. AU - Dunn, Stuart S. AU - Napier, Mary E. AU - DeSimone, Joseph M. T2 - IUBMB LIFE AB - Abstract The first‐generation platforms for vascular drug delivery adopted spherical morphologies. These carriers relied primarily on the size dependence of the enhanced permeability and retention effect to passively target vasculature, resulting in inefficient delivery due to significant variation in endothelial permeability. Enhanced delivery typically requires active targeting via receptor‐mediated endocytosis by surface conjugation of targeting ligands. However, vascular carriers (VCs) still face numerous challenges en route to reaching their targets before delivery. The control of carrier shape offers opportunities to overcome in vivo barriers and enhance vascular drug delivery. Geometric features influence the ability of carrier particles to navigate physiological flow patterns, evade biological clearance mechanisms, sustain circulation, adhere to the vascular surface, and finally transport across or internalize into the endothelium. Although previous formulation strategies limited the fabrication of nonspherical carriers, numerous recent advances in both top‐down and bottom‐up fabrication techniques have enabled shape modulation as a key design element. As part of a series on vascular drug delivery, this review focuses on recent developments in novel vascular platforms with controlled geometry that enhance or modulate delivery functions. Starting with an overview of controlled geometry platforms, we review their shape‐dependent functional characteristics for each stage of their vascular journey in vivo . We sequentially explore carrier geometries that evade reticuloendothelial system uptake, display enhanced circulation persistence and margination dynamics in flow, encourage adhesion to the vascular surface or extravasation through endothelium, and impact extravascular transport and cell internalization. The eventual biodistribution of VCs results from the culmination of their successive navigation of all these barriers and is profoundly influenced by their morphology. To enhance delivery efficacy, carrier designs synergistically combining controlled geometry with standard drug delivery strategies such as targeting moieties, surface decorations, and bulk material properties are discussed. Finally, we speculate on possibilities for innovation, harnessing shape as a design parameter for the next generation of vascular drug delivery platforms. © 2011 IUBMB IUBMB Life, 2011 DA - 2011/8// PY - 2011/8// DO - 10.1002/iub.497 VL - 63 IS - 8 SP - 596-606 SN - 1521-6551 KW - vascular targeting KW - particle platforms KW - controlled geometry KW - drug delivery KW - shape design ER - TY - JOUR TI - Multilayers of Weak Polyelectrolytes of Low and High Molecular Mass Assembled on Polypropylene and Self-Assembled Hydrophobic Surfaces AU - Liu, Xiaomeng AU - Goli, Kiran K. AU - Genzer, Jan AU - Rojas, Orlando J. T2 - LANGMUIR AB - Hydrophobic self-assembled octadecyltrichlorosilane (ODTS), ultrathin films of polypropylene, and ODTS modified with cationic dioctadecyldimethylammonium bromide are employed as substrates for deposition of multilayers of poly(allylamine hydrochloride) and poly(acrylic acid) from aqueous solution. The assembly of highly dissipative polyelectrolyte multilayers (PEMs) is demonstrated by quartz crystal microgravimetry. The initial rate of adsorption is faster and the adsorbed amount larger on the cationic surface, while the detailed structure of the PEMs, as determined by atomic force microscopy imaging, is related primarily to the molecular weight of the adsorbing polymers. A more extensive PEM adsorption on the hydrophobic surfaces takes place with increasing ionic strength of the background electrolyte solution. The water contact angle depends on the type of polymer adsorbed as the outermost layer, indicating that, despite the expected interdiffusion for the different polymer chains, there is a net macromolecular segregation to the free surface. Surface modification with the high molecular weight PEMs produces a more marked reduction of the hydrophilicity of the substrate. DA - 2011/4/19/ PY - 2011/4/19/ DO - 10.1021/la200349p VL - 27 IS - 8 SP - 4541-4550 SN - 0743-7463 ER - TY - JOUR TI - Microviscoelasticity of soft repulsive sphere dispersions: Tracer particle microrheology of triblock copolymer micellar liquids and soft crystals AU - Tanner, Shaun A. AU - Amin, Samiul AU - Kloxin, Christopher J. AU - Zanten, John H. T2 - JOURNAL OF CHEMICAL PHYSICS AB - Tracer particle microrheology using diffusing wave spectroscopy-based microrheology is demonstrated to be a useful method to study the dynamics of aqueous Pluronic™ F108 solutions, which are viewed as solutions of repulsive soft spheres. The measured zero-shear microviscosity of noncrystallizing micellar dispersions indicates micelle corona dehydration upon increasing temperature. Colloidal sphere thermal motion is shown to be exquisitely sensitive to the onset of crystallization in these micellar dispersions. High temperature dynamics are dominated by an apparent soft repulsive micelle-micelle interaction potential indicating the important role played by lubrication forces and ultimately micelle corona interpenetration and compression at sufficiently high concentrations. The measured microscopic viscoelastic storage and loss moduli are qualitatively similar to those experimentally observed in mechanical measurements on colloidal dispersions and crystals, and calculated from mode coupling theory of colloidal suspensions. The observation of subdiffusive colloidal sphere thermal motion at short time-scales is strong evidence that the observed microscopic viscoelastic properties reflect the dynamics of individual micelles rather than a dispersion of micellar crystallites. DA - 2011/5/7/ PY - 2011/5/7/ DO - 10.1063/1.3578183 VL - 134 IS - 17 SP - SN - 1089-7690 ER - TY - JOUR TI - Lithium-oxygen batteries-Limiting factors that affect performance AU - Padbury, Richard AU - Zhang, Xiangwu T2 - JOURNAL OF POWER SOURCES AB - Lithium–oxygen batteries have recently received attention due to their extremely high theoretical energy densities, which far exceed that of any other existing energy storage technology. The significantly larger theoretical energy density of the lithium–oxygen batteries is due to the use of a pure lithium metal anode and the fact that the cathode oxidant, oxygen, is stored externally since it can be readily obtained from the surrounding air. Before the lithium–oxygen batteries can be realized as high performance, commercially viable products, there are still many challenges to overcome, from designing their cathode structure, to optimizing their electrolyte compositions and elucidating the complex chemical reactions that occur during charge and discharge. The scientific obstacles that are related to the performance of the lithium–oxygen batteries open up an exciting opportunity for researchers from many different backgrounds to utilize their unique knowledge and skills to bridge the knowledge gaps that exist in current research projects. This article is a summary of the most significant limiting factors that affect the performance of the lithium–oxygen batteries from the perspective of the authors. The article indicates the relationships that form between various limiting factors and highlights the complex yet captivating nature of the research within this field. DA - 2011/5/15/ PY - 2011/5/15/ DO - 10.1016/j.jpowsour.2011.01.032 VL - 196 IS - 10 SP - 4436-4444 SN - 1873-2755 UR - https://publons.com/publon/7178316/ KW - Lithium-oxygen battery KW - Reaction kinetics KW - Energy density KW - Electrode structure KW - Electrolyte ER - TY - JOUR TI - Electrocatalytic interaction of nano-engineered palladium on carbon nanofibers with hydrogen peroxide and beta-NADH AU - Lin, Zhan AU - Ji, Liwen AU - Medford, Andrew J. AU - Shi, Quan AU - Krause, Wendy E. AU - Zhang, Xiangwu T2 - JOURNAL OF SOLID STATE ELECTROCHEMISTRY DA - 2011/6// PY - 2011/6// DO - 10.1007/s10008-010-1218-2 VL - 15 IS - 6 SP - 1287-1294 SN - 1432-8488 UR - https://publons.com/publon/3117879/ KW - Electrodeposition KW - Pd KW - Carbon nanofibers KW - Hydrogen peroxide KW - beta-NADH ER - TY - JOUR TI - Conformal Organic - Inorganic Hybrid Network Polymer Thin Films by Molecular Layer Deposition using Trimethylaluminum and Glycidol AU - Gong, Bo AU - Peng, Qing AU - Parsons, Gregory N. T2 - JOURNAL OF PHYSICAL CHEMISTRY B AB - Growing interest in nanoscale organic−inorganic hybrid network polymer materials is driving exploration of new bulk and thin film synthesis reaction mechanisms. Molecular layer deposition (MLD) is a vapor-phase deposition process, based on atomic layer deposition (ALD) which proceeds by exposing a surface to an alternating sequence of two or more reactant species, where each surface half-reaction goes to completion before the next reactant exposure. This work describes film growth using trimethyl aluminum and heterobifunctional glycidol at moderate temperatures (90−150 °C), producing a relatively stable organic−inorganic network polymer of the form (−Al−O−(C4H8)−O−)n. Film growth rate and in situ reaction analysis indicate that film growth does not initially follow a steady-state rate, but increases rapidly during early film growth. The mechanism is consistent with subsurface species transport and trapping, previously documented during MLD and ALD on polymers. A water exposure step after the TMA produces a more linear growth rate, likely by blocking TMA subsurface diffusion. Uniform and conformal films are formed on complex nonplanar substrates. Upon postdeposition annealing, films transform into microporous metal oxides with ∼5 Å pore size and surface area as high as ∼327 m2/g, and the resulting structures duplicate the shape of the original substrate. These hybrid films and porous materials could find uses in several research fields including gas separations and diffusion barriers, biomedical scaffolds, high surface area coatings, and others. DA - 2011/5/19/ PY - 2011/5/19/ DO - 10.1021/jp201186k VL - 115 IS - 19 SP - 5930-5938 SN - 1520-6106 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000290427100026&KeyUID=WOS:000290427100026 ER - TY - JOUR TI - Cellulose nanocrystals-based nanocomposites: fruits of a novel biomass research and teaching platform AU - Cao, X. D. AU - Habibi, Y. AU - Magalhaes, W. L. E. AU - Rojas, O. J. AU - Lucia, L. A. T2 - Current Science DA - 2011/// PY - 2011/// VL - 100 IS - 8 SP - 1172-1176 ER - TY - JOUR TI - Single-Ion Conductors for Lithium Batteries via Surface-Initiated Atom Transfer Radical Polymerization AU - Zhang, Hanjun AU - Wei, Xuedong AU - Kopanski, Khalid AU - Shiue, Eric AU - Fedkiw, Peter S. T2 - ADVANCED SCIENCE LETTERS DA - 2011/2// PY - 2011/2// DO - 10.1166/asl.2011.1254 VL - 4 IS - 2 SP - 488-491 SN - 1936-6612 KW - Single-Ion Conductors KW - Silanation KW - Atom Transfer Radical Polymerization KW - Electrolytes KW - Lithium Batteries ER - TY - JOUR TI - Self-Bonding Boards From Plantain Fiber Bundles After Enzymatic Treatment: Adhesion Improvement of Lignocellulosic Products by Enzymatic Pre-Treatment AU - Alvarez, Catalina AU - Rojano, Benjamin AU - Almaza, Ovidio AU - Rojas, Orlando J. AU - Ganan, Piedad T2 - JOURNAL OF POLYMERS AND THE ENVIRONMENT DA - 2011/3// PY - 2011/3// DO - 10.1007/s10924-010-0260-6 VL - 19 IS - 1 SP - 182-188 SN - 1572-8919 KW - Self-bonding KW - Plantain fibers KW - Laccase KW - Boards KW - Free radicals ER - TY - JOUR TI - Poly[diacetonitrile[mu(3)-difluoro(oxalato)borato]sodium] AU - Allen, J. L. AU - Boyle, P. D. AU - Henderson, W. A. T2 - Acta Crystallographica. Section E, Structure Reports Online DA - 2011/// PY - 2011/// VL - 67 SP - M678-388 ER - TY - JOUR TI - Poly[bis(acetonitrile-kappa N)bis[mu(3)-bis(trifluoromethanesulfonyl)imido-kappa O-4,O ':O '':O ''']dilithium] AU - Seo, D. M. AU - Boyle, P. D. AU - Henderson, W. A. T2 - Acta Crystallographica. Section E, Structure Reports Online DA - 2011/// PY - 2011/// VL - 67 SP - M534-317 ER - TY - JOUR TI - Poly[[(acetonitrile)lithium(I)]-mu(3)-tetrafluoridoborato] AU - Seo, Daniel M. AU - Boyle, Paul D. AU - Henderson, Wesley A. T2 - ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE AB - The structure of the title compound, [Li(BF4)(CH3CN)]n, consists of a layered arrangement parallel to (100) in which the Li+ cations are coordinated by three F atoms from three tetra­fluoridoborate (BF4−) anions and an N atom from an acetonitrile mol­ecule. The BF4− anion is coordinated to three different Li+ cations though three F atoms. The structure can be described as being built from vertex-shared BF4 and LiF3(NCCH3) tetra­hedra. These tetra­hedra reside around a crystallographic inversion center and form 8-membered rings. DA - 2011/5// PY - 2011/5// DO - 10.1107/s1600536811012141 VL - 67 SP - M547-U443 SN - 1600-5368 ER - TY - JOUR TI - One-step synthesis of silver nanoparticle-filled nylon 6 nanofibers and their antibacterial properties AU - Shi, Quan AU - Vitchuli, Narendiran AU - Nowak, Joshua AU - Noar, Jesse AU - Caldwell, Jane M. AU - Breidt, Frederick AU - Bourham, Mohamed AU - McCord, Marian AU - Zhang, Xiangwu T2 - JOURNAL OF MATERIALS CHEMISTRY AB - A novel and facile one-step approach to in situ synthesize silver nanoparticle-filled nylon 6 nanofibers by electrospinning is reported. The method does not need post-treatments and can be carried out at ambient conditions without using additional chemicals. It employs the electrospinning solvent as a reducing agent for in situ conversion of AgNO3 into silver nanoparticles during the solution preparation. The resultant silver nanoparticle-filled nylon 6 hybrid nanofibers show an excellent fibrous structure (fiber diameter at 50–150 nm), with narrow size 2–4 nm silver nanoparticles uniformly dispersed throughout the nylon 6 matrix. DSC analysis shows that the in situ incorporation of silver nanoparticles increased the Tg and crystallinity of the resultant nanofibers. These silver nanoparticle-filled nylon 6 nanofibers exhibit a steady and long-lasting silver ion release behavior, and robust antibacterial activity against both Gram-positive B. cereus and Gram-negative E. coli microorganisms. DA - 2011/// PY - 2011/// DO - 10.1039/c1jm11492a VL - 21 IS - 28 SP - 10330-10335 SN - 1364-5501 UR - https://publons.com/publon/274770/ ER - TY - JOUR TI - Novel ice structures in carbon nanopores: pressure enhancement effect of confinement AU - Jazdzewska, Monika AU - Sliwinska-Bartkowiak, Malgorzata M. AU - Beskrovnyy, Anatoly I. AU - Vasilovskiy, Sergey G. AU - Ting, Siu-Wa AU - Chan, Kwong-Yu AU - Huang, Liangliang AU - Gubbins, Keith E. T2 - PHYSICAL CHEMISTRY CHEMICAL PHYSICS AB - We report experimental results on the structure and melting behavior of ice confined in multi-walled carbon nanotubes and ordered mesoporous carbon CMK-3, which is the carbon replica of a SBA-15 silica template. The silica template has cylindrical mesopores with micropores connecting the walls of neighboring mesopores. The structure of the carbon replica material CMK-3 consists of carbon rods connected by smaller side-branches, with quasi-cylindrical mesopores of average pore size 4.9 nm and micropores of 0.6 nm. Neutron diffraction and differential scanning calorimetry have been used to determine the structure of the confined ice and the solid–liquid transition temperature. The results are compared with the behavior of water in multi-walled carbon nanotubes of inner diameters of 2.4 nm and 4 nm studied by the same methods. For D2O in CMK-3 we find evidence of the existence of nanocrystals of cubic ice and ice IX; the diffraction results also suggest the presence of ice VIII, although this is less conclusive. We find evidence of cubic ice in the case of the carbon nanotubes. For bulk water these crystal forms only occur at temperatures below 170 K in the case of cubic ice, and at pressures of hundreds or thousands of MPa in the case of ice VIII and IX. These phases appear to be stabilized by the confinement. DA - 2011/// PY - 2011/// DO - 10.1039/c0cp02797a VL - 13 IS - 19 SP - 9008-9013 SN - 1463-9084 ER - TY - JOUR TI - More Effective Nanomedicines through Particle Design AU - Wang, Jin AU - Byrne, James D. AU - Napier, Mary E. AU - DeSimone, Joseph M. T2 - SMALL AB - Abstract Nanomedicine is an emerging field that applies concepts in nanotechnology to develop novel diagnostics and therapies. Physical and chemical properties of particles, including size, shape, modulus, surface charge and surface chemistry, play an important role in determining particle–cell interactions, cellular trafficking mechanisms, biodistribution, and pharmacokinetics. This discussion focuses on both nanoparticles and microparticles since microparticles can also provide many insights for the development of drug carriers and possess advantages over nanoparticles in certain applications. This review covers recent major advancement in the nanomedicine field and also highlights studies using the PRINT technology. DA - 2011/7/18/ PY - 2011/7/18/ DO - 10.1002/smll.201100442 VL - 7 IS - 14 SP - 1919-1931 SN - 1613-6829 ER - TY - JOUR TI - Modeling the thermodynamic and transport properties of decahydronaphthalene/propane mixtures: Phase equilibria, density, and viscosity AU - Cain, Nathaniel AU - Roberts, George AU - Kiserow, Douglas AU - Carbonell, Ruben T2 - FLUID PHASE EQUILIBRIA AB - Abstract The density and viscosity of propane mixed with 66/34 trans/cis -decahydronaphthalene were measured over a wide range of temperatures (323–423 K), pressures (2.5–208 bar), and compositions (0–65 mol% propane). For conditions giving two phases, the composition of the dense phase was measured in addition to the density and viscosity. The modified Sanchez-Lacombe Equation of State (MSLEOS) was used with a single linearly temperature-dependent pseudo-binary interaction parameter to correlate the phase compositions and densities. The compositions and densities of the mixtures were captured well with absolute average deviations between the model and the data of 5.3% and 2.3%, respectively. The mixture viscosities were computed from a free volume model (FVM) by using a single constant binary interaction parameter. Density predictions from the MSLEOS were used as input mixture density values required for the FVM. The FVM was found to correlate well with the mixture viscosity data with an absolute average deviation between the model and the data of 5.7%. DA - 2011/6/15/ PY - 2011/6/15/ DO - 10.1016/j.fluid.2011.02.009 VL - 305 IS - 1 SP - 25-33 SN - 0378-3812 KW - Phase equilibria KW - Modified Sanchez-Lacombe Equation of State KW - Decahydronaphthalene KW - Propane KW - density KW - Viscosity KW - Volume expansion KW - Viscosity reduction KW - Free volume model for viscosity ER - TY - JOUR TI - Metallothionein-inspired prototype of molecular pincer AU - Voltrova, Svatava AU - Hidasova, Denisa AU - Genzer, Jan AU - Srogl, Jiri T2 - CHEMICAL COMMUNICATIONS AB - Study of Zn and Pb release from complexes with natural and synthetic amidothiol motifs inspired the design of a “molecular pincer” that scavenges quantitatively metals from liquid environment and releases them, on-demand, under very mild oxidative conditions. DA - 2011/// PY - 2011/// DO - 10.1039/c1cc11463h VL - 47 IS - 28 SP - 8067-8069 SN - 1364-548X ER - TY - JOUR TI - Light-Activated Gene Editing with a Photocaged Zinc-Finger Nuclease AU - Chou, Chungjung AU - Deiters, Alexander T2 - ANGEWANDTE CHEMIE-INTERNATIONAL EDITION AB - Light, zinc-finger nuclease, action: Using unnatural amino acid mutagenesis, a light-activated zinc-finger nuclease enzyme was engineered through incorporation of a photocaged tyrosine residue at a DNA–protein interface. The caged zinc-finger nuclease was completely inactive until irradiated with UV light, thus enabling photochemical control of sequence specific gene editing in mammalian cells (see picture). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by 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 - 2011/// PY - 2011/// DO - 10.1002/anie.201101157 VL - 50 IS - 30 SP - 6839-6842 SN - 1433-7851 KW - caged compounds KW - gene technology KW - light-activation KW - mutagenesis KW - zinc-finger nucleases ER - TY - JOUR TI - Computer simulation study of amyloid fibril formation by palindromic sequences in prion peptides AU - Wagoner, Victoria A. AU - Cheon, Mookyung AU - Chang, Iksoo AU - Hall, Carol K. T2 - PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS AB - Abstract We simulate the aggregation of large systems containing palindromic peptides from the Syrian hamster prion protein SHaPrP 113–120 (AGAAAAGA) and the mouse prion protein MoPrP 111–120 (VAGAAAAGAV) and eight sequence variations: GAAAAAAG, (AG) 4 , A8, GAAAGAAA, A10, V10, GAVAAAAVAG, and VAVAAAAVAV The first two peptides are thought to act as the Velcro that holds the parent prion proteins together in amyloid structures and can form fibrils themselves. Kinetic events along the fibrillization pathway influence the types of structures that occur and variations in the sequence affect aggregation kinetics and fibrillar structure. Discontinuous molecular dynamics simulations using the PRIME20 force field are performed on systems containing 48 peptides starting from a random coil configuration. Depending on the sequence, fibrillar structures form spontaneously over a range of temperatures, below which amorphous aggregates form and above which no aggregation occurs. AGAAAAGA forms well organized fibrillar structures whereas VAGAAAAGAV forms less well organized structures that are partially fibrillar and partially amorphous. The degree of order in the fibrillar structure stems in part from the types of kinetic events leading up to its formation, with AGAAAAGA forming less amorphous structures early in the simulation than VAGAAAAGAV. The ability to form fibrils increases as the chain length and the length of the stretch of hydrophobic residues increase. However as the hydrophobicity of the sequence increases, the ability to form well‐ordered structures decreases. Thus, longer hydrophobic sequences form slightly disordered aggregates that are partially fibrillar and partially amorphous. Subtle changes in sequence result in slightly different fibril structures. Proteins 2011; © 2011 Wiley‐Liss, Inc. DA - 2011/7// PY - 2011/7// DO - 10.1002/prot.23034 VL - 79 IS - 7 SP - 2132-2145 SN - 0887-3585 KW - computer simulation KW - peptide KW - aggregation KW - coarse-grained model ER - TY - JOUR TI - Atomic Layer Deposition of Conductive Coatings on Cotton, Paper, and Synthetic Fibers: Conductivity Analysis and Functional Chemical Sensing Using “All-Fiber” Capacitors AU - Jur, Jesse. S. AU - Sweet, William J., III AU - Oldham, Christopher J. AU - Parsons, Gregory N. T2 - Advanced Functional Materials AB - Abstract Conductive coatings on complex fibrous systems are attracting interest for new electronic and other functional systems. Obtaining a quantitative conductivity value for complex surface coatings is often difficult. This work describes a procedure to quantify the effective electrical conductivity of conductive coatings on non‐conductive fibrous networks. By applying a normal force orthogonal to the current and field direction, fiber/fiber contact is improved and consistent conductance values can be measured. Nylon fibers coated with an electroless silver plating shows effective conductivity up to 1950 S cm −1 , and quartz fibers coated with tungsten by atomic layer deposition (ALD) show values up to ∼1150 S cm −1 . Cotton fibers and paper coated with a range of ZnO film thicknesses by ALD show effective conductivity of up to 24 S cm −1 under applied normal force, and conductivity scaled as expected with film coating thickness. Furthermore, we use the conductive coatings to produce an “all‐fiber” metal–insulator–metal capacitor that functions as a liquid chemical sensor. The ability to reliably analyze the effective conductivity of coatings on complex fiber systems will be important to design and improve performance of similar devices and other electronic textiles structures. DA - 2011/3/11/ PY - 2011/3/11/ DO - 10.1002/adfm.201001756 VL - 21 IS - 11 SP - 1993-2002 J2 - Adv. Funct. Mater. LA - en OP - SN - 1616-301X UR - http://dx.doi.org/10.1002/adfm.201001756 DB - Crossref ER - TY - JOUR TI - A frequency shifting liquid metal antenna with pressure responsiveness AU - Khan, Mohammad Rashed AU - Hayes, Gerard J. AU - So, Ju-Hee AU - Lazzi, Gianluca AU - Dickey, Michael D. T2 - APPLIED PHYSICS LETTERS AB - This letter describes the fabrication and characterization of a shape shifting antenna that changes electrical length and therefore, frequency, in a controlled and rapid response to pressure. The antenna is composed of a liquid metal alloy (eutectic gallium indium) injected into microfluidic channels that feature rows of posts that separate adjacent segments of the metal. The initial shape of the antenna is stabilized mechanically by a thin oxide skin that forms on the liquid metal. Rupturing the skin merges distinct segments of the metal, which rapidly changes the length, and therefore frequency, of the antenna. A high speed camera elucidates the mechanism of merging and simulations model accurately the spectral properties of the antennas. DA - 2011/7/4/ PY - 2011/7/4/ DO - 10.1063/1.3603961 VL - 99 IS - 1 SP - SN - 0003-6951 ER - TY - JOUR TI - A comparative study of energy consumption and physical properties of microfibrillated cellulose produced by different processing methods AU - Spence, Kelley L. AU - Venditti, Richard A. AU - Rojas, Orlando J. AU - Habibi, Youssef AU - Pawlak, Joel J. T2 - CELLULOSE DA - 2011/8// PY - 2011/8// DO - 10.1007/s10570-011-9533-z VL - 18 IS - 4 SP - 1097-1111 SN - 1572-882X KW - Processing energy KW - Microfibrillated cellulose KW - Homogenization KW - Microfluidization KW - Micro-grinding KW - Nanofibrillated cellulose ER - TY - JOUR TI - Using mechanobiological mimicry of red blood cells to extend circulation times of hydrogel microparticles AU - Merkel, Timothy J. AU - Jones, Stephen W. AU - Herlihy, Kevin P. AU - Kersey, Farrell R. AU - Shields, Adam R. AU - Napier, Mary AU - Luft, J. Christopher AU - Wu, Huali AU - Zamboni, William C. AU - Wang, Andrew Z. AU - Bear, James E. AU - DeSimone, Joseph M. T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - It has long been hypothesized that elastic modulus governs the biodistribution and circulation times of particles and cells in blood; however, this notion has never been rigorously tested. We synthesized hydrogel microparticles with tunable elasticity in the physiological range, which resemble red blood cells in size and shape, and tested their behavior in vivo. Decreasing the modulus of these particles altered their biodistribution properties, allowing them to bypass several organs, such as the lung, that entrapped their more rigid counterparts, resulting in increasingly longer circulation times well past those of conventional microparticles. An 8-fold decrease in hydrogel modulus correlated to a greater than 30-fold increase in the elimination phase half-life for these particles. These results demonstrate a critical design parameter for hydrogel microparticles. DA - 2011/1/11/ PY - 2011/1/11/ DO - 10.1073/pnas.1010013108 VL - 108 IS - 2 SP - 586-591 SN - 0027-8424 KW - biomimetic KW - deformability KW - drug carriers KW - long circulating KW - red blood cell mimic ER - TY - JOUR TI - Simulating Local Adsorption Isotherms in Structurally Complex Porous Materials: A Direct Assessment of the Slit Pore Model AU - Palmer, Jeremy C. AU - Moore, Joshua D. AU - Brennan, John K. AU - Gubbins, Keith E. T2 - JOURNAL OF PHYSICAL CHEMISTRY LETTERS AB - A fundamental understanding of the behavior of fluids confined in structurally complex nanoporous materials is crucial to the development of improved technologies for environmental remediation and energy storage. We present a computational method for assessing the impact that confinement has on the properties of fluids in model porous materials. The proposed method is demonstrated by calculating pore-size-specific adsorption isotherms and adsorption selectivites in a structurally heterogeneous nanoporous carbon (NPC) model. The results from this method are used to test the predictions made by the ubiquitous slit pore (SP) model. In general, we find that the SP model does not qualitatively capture the behavior of the pore-size-specific adsorption isotherms and selectivites in the NPC structure. These qualitative differences provide significant insight into the origins of the well-known deficiencies of the SP model to predict the adsorption behavior of real NPCs. DA - 2011/2/3/ PY - 2011/2/3/ DO - 10.1021/jz1015668 VL - 2 IS - 3 SP - 165-169 SN - 1948-7185 ER - TY - JOUR TI - Preparation and electrochemical characterization of ionic-conducting lithium lanthanum titanate oxide/polyacrylonitrile submicron composite fiber-based lithium-ion battery separators AU - Liang, Yinzheng AU - Ji, Liwen AU - Guo, Bingkun AU - Lin, Zhan AU - Yao, Yingfang AU - Li, Ying AU - Alcoutlabi, Mataz AU - Qiu, Yiping AU - Zhang, Xiangwu T2 - JOURNAL OF POWER SOURCES AB - Lithium lanthanum titanate oxide (LLTO)/polyacrylonitrile (PAN) submicron composite fiber-based membranes were prepared by electrospinning dispersions of LLTO ceramic particles in PAN solutions. These ionic-conducting LLTO/PAN composite fiber-based membranes can be directly used as lithium-ion battery separators due to their unique porous structure. Ionic conductivities were evaluated after soaking the electrospun LLTO/PAN composite fiber-based membranes in a liquid electrolyte, 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1:1 vol). It was found that, among membranes with various LLTO contents, 15 wt.% LLTO/PAN composite fiber-based membranes provided the highest ionic conductivity, 1.95 × 10−3 S cm−1. Compared with pure PAN fiber membranes, LLTO/PAN composite fiber-based membranes had greater liquid electrolyte uptake, higher electrochemical stability window, and lower interfacial resistance with lithium. In addition, lithium//1 M LiPF6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes as the separator exhibited high discharge specific capacity of 162 mAh g−1 and good cycling performance at 0.2 C rate at room temperature. DA - 2011/1/1/ PY - 2011/1/1/ DO - 10.1016/j.jpowsour.2010.06.088 VL - 196 IS - 1 SP - 436-441 SN - 1873-2755 UR - https://publons.com/publon/6540087/ KW - Lithium-ion batteries KW - Separators KW - Electrospinning KW - Submicron fibers KW - LLTO ER - TY - JOUR TI - Permeation of a cationic polyelectrolyte into mesoporous silica Part 3. Using adsorption isotherms to elucidate streaming potential results AU - Hubbe, M. A. AU - Wu, N. AU - Rojas, O. J. AU - Park, S. T2 - Colloids and Surfaces. A, Physicochemical and Engineering Aspects DA - 2011/// PY - 2011/// VL - 381 IS - 1-3 SP - 1-6 ER - TY - JOUR TI - Glycoside Hydrolase Inventory Drives Plant Polysaccharide Deconstruction by the Extremely Thermophilic Bacterium Caldicellulosiruptor saccharolyticus AU - VanFossen, Amy L. AU - Ozdemir, Inci AU - Zelin, Samantha L. AU - Kelly, Robert M. T2 - BIOTECHNOLOGY AND BIOENGINEERING AB - Abstract The genome of Caldicellulosiruptor saccharolyticus encodes a range of glycoside hydrolases (GHs) that mediate plant biomass deconstruction by this bacterium. Two GH‐based genomic loci that appear to be central to the hydrolysis of hemicellulosic and cellulosic substrates were examined. XynB‐XynF (Csac_2404‐Csac_2411) encodes intracellular and extracellular GHs that are active towards xylan and xylan side‐chains, as well as carboxymethyl cellulose (CMC). XynD (Csac_2409) and XynE (Csac_2410) were produced recombinantly and confirmed to be xylanases. XynF (Csac_2411) was produced in two separate polypeptides, each with one GH43 catalytic domain displaying α‐ L ‐arabinofuranosidase activity. CelA‐ManB (Csac_1076‐Csac_1080) encodes four multi‐domain, extracellular GHs, including CelB (Csac_1078), a 118 kDa extracellular enzyme not present in the other genome‐sequenced member of this genus, Caldicellulosiruptor bescii (formerly Anaerocellum thermophilum ). CelB contains both GH10 and GH5 domains, separated by a family 3 carbohydrate‐binding module (CBM3). CelB encoded in Csac_1078 differed from the version originally reported (Saul et al., 1990, Appl Environ Microbiol 56:3117–3124) with respect to linker regions. CelB hydrolyzed xylan and CMC, as well as barley β‐glucan, glucomannan, and arabinoxylan. For all substrates tested, intact CelB was significantly more active than either the individual GH5 and GH10 domains or the two discrete domains together, indicating that the multi‐domain architecture is essential for complex carbohydrate hydrolysis. Transcriptomes for C. saccharolyticus grown at 70°C on glucose, xylose, xyloglucan, switchgrass, and poplar revealed that certain GHs were particularly responsive to growth on switchgrass and poplar and that CelB was in the top decile of all transcripts during growth on the plant biomass. Biotechnol. Bioeng. 2011; 108:1559–1569. © 2011 Wiley Periodicals, Inc. DA - 2011/7// PY - 2011/7// DO - 10.1002/bit.23093 VL - 108 IS - 7 SP - 1559-1569 SN - 1097-0290 KW - Caldicellulosiruptor saccharolyticus KW - extreme thermophile KW - plant biomass KW - glycoside hydrolases ER - TY - JOUR TI - Dynamic modelling of whey protein-saliva interactions in the mouth and relation to astringency in acidic beverages AU - Andrewes, P. AU - Kelly, M. AU - Vardhanabhuti, B. AU - Foegeding, E. A. T2 - INTERNATIONAL DAIRY JOURNAL AB - Whey proteins in acidic beverages (pH < 4.5) are astringent, producing a dry mouth-feel. Astringency is thought to be caused by interaction of food components with saliva, often leading to aggregate formation. Such interactions decrease saliva lubrication, form rough particles, and probably increase friction on oral surfaces – changing mouth-feel. Dynamic in vitro models were constructed to reproduce the likely interaction of whey proteins with saliva in the mouth during the course of beverage ingestion. Aggregate formation in the models was examined for numerous whey protein solutions under different conditions. Trends observed in the models were consistent with previous reported sensory evaluations of whey protein astringency. For example, maximum turbidity changed little in the models with increasing protein concentration, consistent with literature describing little increase in astringency with increasing protein concentration. Modelling mouth conditions, to measure protein–saliva interactions, related to astringency better than mixing saliva and protein in simple ratios. DA - 2011/8// PY - 2011/8// DO - 10.1016/j.idairyj.2011.02.011 VL - 21 IS - 8 SP - 523-530 SN - 1879-0143 ER - TY - JOUR TI - The role of molecular modeling in confined systems: impact and prospects AU - Gubbins, Keith E. AU - Liu, Ying-Chun AU - Moore, Joshua D. AU - Palmer, Jeremy C. T2 - PHYSICAL CHEMISTRY CHEMICAL PHYSICS AB - Molecular modeling at the electronic and atomistic levels plays an important and complementary role to experimental studies of confinement effects. Theory and atomistic simulation can provide fundamental understanding, determine the limits of well known macroscopic laws such as Kelvin's equation, provide predictions for systems that are difficult to study via experiment (e.g. adsorption of highly toxic gases), and can be used to gain detailed molecular level information that may not be accessible in the laboratory (e.g. the local structure and composition of confined phases). We describe the most important and useful methods that are based firmly on quantum mechanics and statistical mechanics, including ab intio and classical density functional theories, and Monte Carlo and molecular dynamics simulation. We discuss their strengths and limitations. We then describe examples of applications of these methods to adsorption and equilibrium properties, including testing the Kelvin equation, determination of pore size distributions and capillary phenomena. Applications to self and transport diffusion, including single-file and anomalous diffusion, and viscous flow in nanoporous materials are described. The use of these methods to understand confinement effects on chemical reactions in heterogeneous media is treated, including effects on reaction equilibria, rates and mechanism. Finally we discuss the current status of molecular modeling in this area, and the outlook and future research needs for the next few years. The treatment is suitable for the general technical reader. DA - 2011/// PY - 2011/// DO - 10.1039/c0cp01475c VL - 13 IS - 1 SP - 58-85 SN - 1463-9084 ER - TY - JOUR TI - Potent Engineered PLGA Nanoparticles by Virtue of Exceptionally High Chemotherapeutic Loadings AU - Enlow, Elizabeth M. AU - Luft, J. Christopher AU - Napier, Mary E. AU - DeSimone, Joseph M. T2 - NANO LETTERS AB - Herein we report the fabrication of engineered poly(lactic acid-co-glycolic acid) nanoparticles via the PRINT (particle replication in nonwetting templates) process with high and efficient loadings of docetaxel, up to 40% (w/w) with encapsulation efficiencies >90%. The PRINT process enables independent control of particle properties leading to a higher degree of tailorability than traditional methods. Particles with 40% loading display better in vitro efficacy than particles with lower loadings and the clinical formulation of docetaxel, Taxotere. DA - 2011/2// PY - 2011/2// DO - 10.1021/nl104117p VL - 11 IS - 2 SP - 808-813 SN - 1530-6992 KW - PLGA KW - nanoparticle KW - docetaxel KW - PRINT ER - TY - JOUR TI - Multilayers of Low Charge Density Polyelectrolytes on Thin Films of Carboxymethylated and Cationic Cellulose AU - Wang, Zhengjia AU - Hauser, Peter J. AU - Laine, Janne AU - Rojas, Orlando J. T2 - JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY AB - Multilayers with low charge density polyelectrolytes assembled on thin films of cellulose were studied by piezoelectric microgravimetry. The substrates were produced from colloidal suspensions of cotton fibers before and after modification with cationic and anionic groups via epoxy intermediates of quaternary ammonium and carboxymethylation, respectively. Two different levels of ionicity were used for each cellulosic substrate in order to investigate the role of the supporting surface in the buildup of the multilayer. It was found that while electrostatic interactions were leading factors in the assembly of high molecular weight, low charge density polyelectrolytes, other effects such as van der Waals and secondary cooperative forces played important roles. The charge properties of the substrate and the adsorbing polymer were relevant to the behavior of the self-assembled multilayers. Sequential additions of weak polyelectrolytes formed viscoelastic layers on all cellulose substrates. Adsorption of the first layer depended heavily on the charge characteristics of the substrate while the buildup of subsequent layers was mainly affected by the outermost adsorbed polymer. The polyelectrolyte multilayer formation with highest total adsorbed mass occurred on unmodified cellulose surfaces; therefore, in the case of the low charge density polyelectrolytes studied, substrate ionicity and functionalization may not be a requirement. Finally, the effect of anionic weak polyelectrolytes added after the first adsorbed polymer pair is highlighted in the context of reported observations for polyelectrolytes of high charge density. DA - 2011/// PY - 2011/// DO - 10.1163/016942410x525876 VL - 25 IS - 6-7 SP - 643-660 SN - 1568-5616 KW - Polyelectrolyte multilayer KW - adsorption KW - cationic cellulose KW - anionic cellulose KW - cotton KW - adhesion KW - QCM ER - TY - JOUR TI - Making inert polypropylene fibers chemically responsive by combining atomic layer deposition and vapor phase chemical grafting AU - Peng, Qing AU - Gong, Bo AU - Parsons, Gregory N. T2 - NANOTECHNOLOGY AB - Uniformly grafting organic reactive molecular species, e.g. –NH2, onto substrates that have three-dimensional complex structures and are chemically inert is challenging. The vapor phase chemical grafting of organic molecules enabled by low temperature metal oxide atomic layer deposition (ALD) is presented as a general and promising solution to functionalize inert matrices with complex morphology, such as nonwoven polypropylene mats, through the controllable self-limited molecular assembly mechanism in a combined ALD and vapor phase chemical grafting process. DA - 2011/4/15/ PY - 2011/4/15/ DO - 10.1088/0957-4484/22/15/155601 VL - 22 IS - 15 SP - SN - 1361-6528 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000288209700007&KeyUID=WOS:000288209700007 ER - TY - JOUR TI - Genetically encoding an aliphatic diazirine for protein photocrosslinking AU - Chou, Chungjung AU - Uprety, Rajendra AU - Davis, Lloyd AU - Chin, Jason W. AU - Deiters, Alexander T2 - CHEMICAL SCIENCE AB - Photocrosslinking is an important approach that allows discovery and detailed investigation of protein–protein, protein–oligonucleotide, and protein–small molecule interactions with high temporal and spatial resolution. A major limitation to the universal application of this methodology is the site-specific introduction of efficient aliphatic photocrosslinking probes into proteins of interest. Here, we report a novel aliphatic diazirine amino acid and its genetically encoded, site-specific incorporation into proteins in bacterial and mammalian cells. Furthermore, we demonstrate efficient photocrosslinking of a test proteinin vitro and in vivo. DA - 2011/// PY - 2011/// DO - 10.1039/c0sc00373e VL - 2 IS - 3 SP - 480-483 SN - 2041-6539 ER - TY - JOUR TI - Capillary condensation in deformable mesopores: wetting versus nanomechanics AU - Schoen, Martin AU - Guenther, Gerrit T2 - MOLECULAR PHYSICS AB - We employ grand canonical ensemble Monte Carlo simulations to investigate the strain experienced by a nanoscopic slit pore when this pore fills with fluid material. Both solid substrates of our model system consist of a single layer of solid atoms bound to their equilibrium lattice sites by a harmonic potential such that these atoms are thermally coupled to molecules of a fluid phase confined between them. Parameters are tuned such that they represent an experimental situation in which pentane is adsorbed by mesoporous silica. Our focus is on strain isotherms, that is the net deformation of the solid as fluid material is imbibed by the pore. At low pressures prior to pore filling, strain isotherms are dominated by wetting characteristics of the fluid–solid interface whereas nanomechanical properties of the pore may be deduced quantitatively from high-pressure portions of the strain isotherm after the pore is completely filled with fluid. To that end we introduce a thermodynamic analysis of the high-pressure portion of the sorption isotherm that permits us to determine the elasticity of the confining solid material in terms of a so-called pore-load modulus which is also experimentally accessible. DA - 2011/// PY - 2011/// DO - 10.1080/00268976.2010.513346 VL - 109 IS - 1 SP - 83-95 SN - 1362-3028 KW - phase transition KW - capillary condensation KW - sorption strain KW - Monte Carlo simulation ER - TY - JOUR TI - Ultrathin film coatings of aligned cellulose nanocrystals from a convective-shear assembly system and their surface mechanical properties AU - Hoeger, Ingrid AU - Rojas, Orlando J. AU - Efimenko, Kirill AU - Velev, Orlin D. AU - Kelley, Steve S. T2 - Soft Matter AB - Ultrathin films of aligned cellulose nanocrystals (CNCs) were deposited on solid supports by using convective and shear forces. Compared to previous systems involving high electric or magnetic fields to control the orientation of these rod-like natural nanoparticles, the proposed process of alignment was very simple, inexpensive and with potential for scale up. The effect of concentration of CNC in aqueous suspensions, type of solid support, relative humidity and rates of withdrawal of the deposition plate were determined by using atomic force microscopy (AFM) and ellipsometry. The degree of orientation was quantified from the number density of CNCs in leading angles by using image analyses. Also, the contribution of shear and capillary forces on alignment parallel and normal to the withdrawal direction was elucidated. The best alignment of CNCs in the withdrawal direction, favored by shear effects, was achieved with gold and silica supports with a pre-adsorbed cationic polyelectrolyte layer and at a CNC suspension concentration above 2.5% (w/w), below the critical concentration for chiral nematic phase separation. Compared to the bare solid support, nanoindentation of the obtained coatings of ultrathin films of oriented CNCs provided enhanced surface mechanical strength and wear resistance. A transverse Young's modulus, hardness and coefficient of friction of 8.3 ± 0.9 GPa, 0.38 ± 0.03 GPa and 0.51 ± 0.23 GPa, respectively, were measured. Notably, the transverse Young's modulus was found to be in agreement with reported values predicted by molecular modeling and measured for single CNCs by using atomic force microscopy. DA - 2011/// PY - 2011/// DO - 10.1039/c0sm01113d VL - 7 IS - 5 SP - 1957 J2 - Soft Matter LA - en OP - SN - 1744-683X 1744-6848 UR - http://dx.doi.org/10.1039/c0sm01113d DB - Crossref ER - TY - JOUR TI - Recombinant Human Interleukin-11 Treatment Enhances Collateral Vessel Growth After Femoral Artery Ligation AU - Aitsebaomo, Julius AU - Srivastava, Siddharth AU - Zhang, Hua AU - Jha, Sushmita AU - Wang, Zhongjing AU - Winnik, Stephan AU - Veleva, Anka N. AU - Pi, Xinchun AU - Lockyer, Pamela AU - Faber, James E. AU - Patterson, Cam T2 - ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY AB - To investigate the role of recombinant human interleukin-11 (rhIL-11) on in vivo mobilization of CD34(+)/vascular endothelial growth factor receptor (VEGFR) 2(+) mononuclear cells and collateral vessel remodeling in a mouse model of hindlimb ischemia.We observed that treatment of Sv129 mice with continuous infusion of 200-μg/kg rhIL-11 per day led to in vivo mobilization of CD34(+)/VEGFR2(+) cells that peaked at 72 hours. Sv129 mice pretreated with rhIL-11 for 72 hours before femoral artery ligation showed a 3-fold increase in plantar vessel perfusion, leading to faster blood flow recovery; and a 20-fold increase in circulating CD34(+)/VEGFR2(+) cells after 8 days of rhIL-11 treatment. Histologically, experimental mice had a 3-fold increase in collateral vessel luminal diameter after 21 days of rhIL-11 treatment and a 4.4-fold influx of perivascular CD34(+)/VEGFR2(+) cells after 8 days of therapy. Functionally, rhIL-11-treated mice showed better hindlimb appearance and use scores when compared with syngeneic mice treated with PBS under the same experimental conditions.These novel findings show that rhIL-11 promotes in vivo mobilization of CD34(+)/VEGFR2(+) mononuclear cells, enhances collateral vessel growth, and increases recovery of perfusion after femoral artery ligation. Thus, rhIL-11 has a promising role for development as an adjunctive treatment of patients with peripheral vascular disease. DA - 2011/2// PY - 2011/2// DO - 10.1161/atvbaha.110.216986 VL - 31 IS - 2 SP - 306-312 SN - 1524-4636 KW - blood flow KW - ischemia KW - peripheral arterial disease KW - peripheral vasculature KW - reperfusion ER - TY - JOUR TI - Inherently aligned microfluidic electrodes composed of liquid metal AU - So, Ju-Hee AU - Dickey, Michael D. T2 - LAB ON A CHIP AB - This paper describes the fabrication and characterization of microelectrodes that are inherently aligned with microfluidic channels and in direct contact with the fluid in the channels. Injecting low melting point alloys, such as eutectic gallium indium (EGaIn), into microchannels at room temperature (or just above room temperature) offers a simple way to fabricate microelectrodes. The channels that define the shape and position of the microelectrodes are fabricated simultaneously with other microfluidic channels (i.e., those used to manipulate fluids) in a single step; consequently, all of the components are inherently aligned. In contrast, conventional techniques require multiple fabrication steps and registration (i.e., alignment of the electrodes with the microfluidic channels), which are technically challenging. The distinguishing characteristic of this work is that the electrodes are in direct contact with the fluid in the microfluidic channel, which is useful for a number of applications such as electrophoresis. Periodic posts between the microelectrodes and the microfluidic channel prevent the liquid metal from entering the microfluidic channel during injection. A thin oxide skin that forms rapidly and spontaneously on the surface of the metal stabilizes mechanically the otherwise low viscosity, high surface tension fluid within the channel. Moreover, the injected electrodes vertically span the sidewalls of the channel, which allows for the application of uniform electric field lines throughout the height of the channel and perpendicular to the direction of flow. The electrodes are mechanically stable over operating conditions commonly used in microfluidic applications; the mechanical stability depends on the magnitude of the applied bias, the nature of the bias (DC vs. AC), and the conductivity of the solutions in the microfluidic channel. Electrodes formed using alloys with melting points above room temperature ensure mechanical stability over all of the conditions explored. As a demonstration of their utility, the fluidic electrodes are used for electrohydrodynamic mixing, which requires extremely high electric fields (~10(5) V m(-1)). DA - 2011/// PY - 2011/// DO - 10.1039/c0lc00501k VL - 11 IS - 5 SP - 905-911 SN - 1473-0189 ER - TY - JOUR TI - Fuel-structure dependence of benzene formation processes in premixed flames fueled by C6H12 isomers AU - Hansen, N. AU - Kasper, T. AU - Yang, B. AU - Cool, T.A. AU - Li, W. AU - Westmoreland, P.R. AU - Oßwald, P. AU - Kohse-Höinghaus, K. T2 - Proceedings of the Combustion Institute AB - The fuel-structure-dependent significance of various benzene formation pathways is analyzed using data from rich (ϕ = 1.7) flames fueled by four C6H12 isomers: 1-hexene, cyclohexane, methylcyclopentane, and 3,3-dimethyl-1-butene. The isomer-resolved chemical compositions of the four premixed, laminar low-pressure flat flames are determined by flame-sampling molecular-beam mass spectrometry employing single-photon ionization by synchrotron generated vacuum-ultraviolet photons. Isomer-resolving photoionization efficiency curves and quantitative mole fraction profiles reveal the dominant fuel destruction pathways, the influence of different fuel consumption processes on the formation of commonly considered benzene precursors, and the contributions of several routes towards benzene formation. While propargyl and allyl radicals dominate benzene formation in the combustion of 1-hexene, contributions from reactions involving i-C4H5 and C5H5 radicals are revealed in the flames of 3,3-dimethyl-1-butene and methylcyclopentane, respectively. Close to the burner surface, successive dehydrogenation of the fuel is found to be important for the cyclohexane flame and to some smaller extent for the methylcyclopentane flame. DA - 2011/// PY - 2011/// DO - 10.1016/j.proci.2010.05.056 VL - 33 IS - 1 SP - 585-592 J2 - Proceedings of the Combustion Institute LA - en OP - SN - 1540-7489 UR - http://dx.doi.org/10.1016/j.proci.2010.05.056 DB - Crossref KW - C6H12 fuels KW - Laminar flames KW - Mass spectrometry KW - Benzene formation ER - TY - JOUR TI - Finite-size scaling analysis of isotropic-nematic phase transitions in an anisometric Lennard-Jones fluid AU - Greschek, Manuel AU - Schoen, Martin T2 - PHYSICAL REVIEW E AB - By means of Monte Carlo simulations in the isothermal-isobaric ensemble, we perform a finite-size scaling analysis of the isotropic-nematic (IN) phase transition. Our model consists of egg-shaped anisometric Lennard-Jones molecules. We employ the cumulant intersection method to locate the pressure P* at which the IN phase transition occurs at a given temperature T. In particular, we focus on second-order cumulants of the largest and middle eigenvalues of the alignment tensor. At fixed T, cumulants for various system sizes intersect at a unique pressure P*. Various known scaling relations for these cumulants are verified numerically. At P*, the isobaric heat capacity passes through a maximum value c(P)(m), which depends on the number of molecules N. This dependency can accurately be described by a power law such that lim(N→∞)c(P)(m)(N)→∞. For sufficiently large N, the pressure at which c(P)(m) is located shifts only very slightly in agreement with the apparent insensitivity of the cumulant intersection to N. In addition, we analyze our data in terms of Landau's theory of phase transitions. Our results are consistent with a weakly discontinuous entropy-driven phase transition. DA - 2011/1/21/ PY - 2011/1/21/ DO - 10.1103/physreve.83.011704 VL - 83 IS - 1 SP - SN - 1550-2376 ER - TY - JOUR TI - Exceptional versatility of solvated block copolymer/ionomer networks as electroactive polymers AU - Vargantwar, Pruthesh H. AU - Shankar, Ravi AU - Krishnan, Arjun S. AU - Ghosh, Tushar K. AU - Spontak, Richard J. T2 - SOFT MATTER AB - Responsive materials possess properties that change abruptly when exposed to an external stimulus, and electroactive polymers constitute examples of robust, lightweight materials that change shape upon electrical actuation. We demonstrate that solvated block copolymer networks afford tremendous versatility in designing electronic and ionic electroactive polymers. As dielectric elastomers, styrenic block copolymer systems attain extraordinary actuation strains approaching 300%, along with high electromechanical coupling efficiencies. Changing the solvent improves the blocking stress and yields remarkably high energy densities, while providing a unique opportunity for mechanical impedance matching and control of shape recovery kinetics, as well as mode of deformation. Dielectric elastomers composed of acrylic copolymers actuate beyond 100% in-plane strain without any prestrain, whereas block ionomer networks swollen with ionic solutions yield ionic polymer–metal composites, which actuate by bending. Selective solvation of block copolymer networks represents an effective and largely unexplored means by which to tune the function and properties of electroactive polymers through systematic manipulation of copolymer and solvent attributes. DA - 2011/// PY - 2011/// DO - 10.1039/c0sm01210f VL - 7 IS - 5 SP - 1651-1655 SN - 1744-6848 ER - TY - JOUR TI - Efficient In Vivo Selection of a Novel Tumor-Associated Peptide from a Phage Display Library AU - Veleva, Anka N. AU - Nepal, Desh B. AU - Frederick, C. Brandon AU - Schwab, Jacob AU - Lockyer, Pamela AU - Yuan, Hong AU - Lalush, David S. AU - Patterson, Cam T2 - MOLECULES AB - We developed a screening procedure to identify ligands from a phage display random peptide library that are selective for circulating bone marrow derived cells homing to angiogenic tumors. Panning the library on blood outgrowth endothelial cell suspension in vitro followed by in vivo selection based on homing of bone marrow-bound phage to angiogenic tumors, yielded the peptide QFPPKLTNNSML. Upon intravenous injection phage displaying this peptide homed to Lewis lung carcinoma (LLC) tumors in vivo whereas control phage did not localize to tumor tissue. Phage carrying the QFPPKLTNNSML peptide labeled with 64Cu radionuclide when administered intravenously into a tumor bearing mouse was detected noninvasively with positron emission tomography (PET) around the tumor. These proof-of-principle experiments demonstrate the ability of the QFPPKLTNNSML peptide to deliver payload (radiolabeled phage conjugates) in vivo to sites of ongoing angiogenesis and point to its potential clinical utility in a variety of physiologic and pathologic processes where neovascular growth is a critical component. DA - 2011/1// PY - 2011/1// DO - 10.3390/molecules160109 VL - 16 IS - 1 SP - 900-914 SN - 1420-3049 KW - in vivo phage display KW - circulating bone marrow derived tumor homing cells KW - tumor-associated peptides KW - targeting neovascular growth KW - positron emission tomography (PET) imaging ER - TY - JOUR TI - Effects of solar UV and climate change on materials AU - Andrady, A. L. AU - Hamid, H. AU - Torikai, A. T2 - PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES AB - Increased solar ultraviolet radiation (UV) reaches the surface of the Earth as a consequence of a depleted stratospheric ozone layer and changes in factors such as cloud cover, land-use patterns and aerosols. Climate change is expected to result in a 1.1-6.4 °C increase in average temperature by the end of this century, depending on location. Increased levels of UV radiation, especially at high ambient temperatures, are well-known to accelerate the degradation of plastics, rubber and wood materials, thereby reducing their useful lifetimes in outdoor applications. Plastics used routinely outdoors are generally light-stabilized using chemical additives to ensure their useful lifetimes. Wood products are coated for resistance to UV radiation, since photodamage results in enhanced water-susceptibility and their consequent biodegradation under outdoor exposure. The increased damage to materials due to an increased UV-B (280-315 nm) component in solar radiation reaching the Earth likely can be countered using light-stabilization technologies, surface coatings or, in most instances, by substituting the materials in question with greater UV radiation-resistant materials. However, even if these options could be used with all common materials affected, they will invariably result in higher costs. Reliable estimates of the incremental costs involved depend on the anticipated damage and the effectiveness of mitigation strategies employed. We summarize and assess recent findings on light-induced damage to plastic materials, including wood-plastics composites and nanocomposites. The combined effect of increased UV-B radiation and ambient temperature is of special interest, since these two factors represent particularly harsh environmental conditions for most materials. Advances in approaches to light stabilization of materials are also assessed. DA - 2011/// PY - 2011/// DO - 10.1039/c0pp90038a VL - 10 IS - 2 SP - 292-300 SN - 1474-9092 ER - TY - JOUR TI - Atomic layer deposition of titanium dioxide on cellulose acetate for enhanced hemostasis AU - Hyde, G. Kevin AU - Stewart, S. Michael AU - Scarel, Giovanna AU - Parsons, Gregory N. AU - Shih, Chun-Che AU - Shih, Chun-Ming AU - Lin, Shing-Jong AU - Su, Yea-Yang AU - Monteiro-Riviere, Nancy A. AU - Narayan, Roger J. T2 - BIOTECHNOLOGY JOURNAL AB - TiO₂ films may be used to alter the wettability and hemocompatibility of cellulose materials. In this study, pure and stoichiometric TiO₂ films were grown using atomic layer deposition on both silicon and cellulose substrates. The films were grown with uniform thicknesses and with a growth rate in agreement with literature results. The TiO₂ films were shown to profoundly alter the water contact angle values of cellulose in a manner dependent upon processing characteristics. Higher amounts of protein adsorption indicated by blurry areas on images generated by scanning electron microscopy were noted on TiO₂ -coated cellulose acetate than on uncoated cellulose acetate. These results suggest that atomic layer deposition is an appropriate method for improving the biological properties of hemostatic agents and other blood-contacting biomaterials. DA - 2011/2// PY - 2011/2// DO - 10.1002/biot.201000342 VL - 6 IS - 2 SP - 213-223 SN - 1860-7314 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000287718500010&KeyUID=WOS:000287718500010 KW - Biomaterials KW - Cellulose KW - Hemocompatibility KW - Hemostatic agent KW - Titanium oxide ER - TY - JOUR TI - Atomic Layer Deposition of Al2O3 and ZnO at Atmospheric Pressure in a Flow Tube Reactor AU - Jur, Jesse S. AU - Parsons, Gregory N. T2 - ACS APPLIED MATERIALS & INTERFACES AB - Improving nanoscale thin film deposition techniques such as atomic layer deposition (ALD) to permit operation at ambient pressure is important for high-throughput roll-to-roll processing of emerging flexible substrates, including polymer sheets and textiles. We present and investigate a novel reactor design for inorganic materials growth by ALD at atmospheric pressure. The reactor uses a custom “pressure boost” approach for delivery of low vapor pressure ALD precursors that controls precursor dose independent of reactor pressure. Analysis of continuum gas flow in the reactor shows key relations among reactor pressure, inert gas flow rate, and species diffusion that define conditions needed to efficiently remove product and adsorbed reactive species from the substrate surface during the inert gas purge cycle. Experimental results, including in situ quartz crystal microbalance (QCM) characterization and film thickness measurements for deposition of ZnO and Al2O3 are presented and analyzed as a function of pressure and gas flow rates at 100 °C. At atmospheric pressure and high gas flow, ZnO deposition can proceed at the same mass uptake and growth rate as observed during more typical low pressure ALD. However, under the same high pressure and flow conditions the mass uptake and growth rate for Al2O3 is a factor of ∼1.5−2 larger than at low pressure. Under these conditions, Al2O3 growth at atmospheric pressure in a “flow-through” geometry on complex high surface area textile materials is sufficiently uniform to yield functional uniform coatings. DA - 2011/2// PY - 2011/2// DO - 10.1021/am100940g VL - 3 IS - 2 SP - 299-308 SN - 1944-8252 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000287639400029&KeyUID=WOS:000287639400029 KW - atmospheric pressure KW - atomic layer deposition KW - roll-to-roll KW - textiles KW - thin film growth KW - Al2O3 KW - ZnO ER - TY - JOUR TI - Adsorptive behavior of CO2, CH4 and their mixtures in carbon nanospace: a molecular simulation study AU - Palmer, Jeremy C. AU - Moore, Joshua D. AU - Roussel, Thomas J. AU - Brennan, John K. AU - Gubbins, Keith E. T2 - PHYSICAL CHEMISTRY CHEMICAL PHYSICS AB - Using molecular simulation, four types of nanoporous carbons are examined as adsorbents for the separation of CO(2)/CH(4) mixtures at ambient temperature and pressures up to 10 MPa. First, the adsorption selectivity of CO(2) is investigated in carbon slit pores and single-walled carbon nanotube bundles in order to find the optimal pore dimensions for CO(2) separation. Then, the adsorptive properties of the optimized slit pore and nanotube bundle are compared with two realistic nanoporous carbon models: a carbon replica of zeolite Y and an amorphous carbon. For the four carbon models, adsorption isotherms and isosteric heats of adsorption are presented for both pure components and mixtures. Special attention is given to the calculation of excess isotherms and isosteric heats, which are necessary to assess the performance of model nanoporous materials in the context of experimental measurements. From these results, we discuss the impact that variables such as pore size, pore morphology, pressure and mixture composition have on the performance of nanoporous carbons for CO(2) separation. DA - 2011/// PY - 2011/// DO - 10.1039/c0cp02281k VL - 13 IS - 9 SP - 3985-3996 SN - 1463-9084 ER - TY - JOUR TI - Adsorption, structure and dynamics of benzene in ordered and disordered porous carbons AU - Coasne, Benoit AU - Alba-Simionesco, Christiane AU - Audonnet, Fabrice AU - Dosseh, Gilberte AU - Gubbins, Keith E. T2 - PHYSICAL CHEMISTRY CHEMICAL PHYSICS AB - Molecular simulations are used to study the adsorption, structure, and dynamics of benzene at 298 K in atomistic models of ordered and disordered nanoporous carbons. The ordered porous carbon is a regular slit pore made up of graphene sheets. The disordered porous carbon is a structural model that reproduces the morphological (pore shape) and topological (pore connectivity) disorder of saccharose-based porous carbons. As expected for pores of a regular geometry, the filling occurs at well-defined pressures which are an increasing function of the pore width H. In contrast, in qualitative agreement with experimental data for activated carbon fibers, the filling of the disordered carbon is continuous and spans over a large pressure range. The structure and dynamics of benzene in the disordered carbon also strongly depart from that for the slit pore geometry. While benzene in the slit graphite nanopores exhibits significant layering, benzene in the disordered porous carbon exhibits a liquid-like structure very close to its bulk counterpart. Both the ordering and self-diffusivity of benzene in the graphite nanopores depend in a complex manner on the pore width. The dynamics is either slower or faster than its bulk counterpart; our data show that the self-diffusivity decreases as the number of confined layers n divided by the pore width H increases (except for very small pore sizes for which benzene crystallizes and is necessarily slower than the liquid phase). The dynamics of benzene in the disordered porous carbon is isotropic and is much slower than that for the graphite slit nanopores (even with the smallest slit nanopore considered in this work). The results above show that the adsorption, structure, and dynamics of benzene confined in disordered porous carbons cannot be described in simple terms using an ideal model such as the slit pore geometry. DA - 2011/// PY - 2011/// DO - 10.1039/c0cp02205e VL - 13 IS - 9 SP - 3748-3757 SN - 1463-9084 ER - TY - JOUR TI - Adsorption and diffusion of argon in disordered nanoporous carbons AU - Palmer, Jeremy C. AU - Moore, Joshua D. AU - Brennan, John K. AU - Gubbins, Keith E. T2 - ADSORPTION-JOURNAL OF THE INTERNATIONAL ADSORPTION SOCIETY DA - 2011/2// PY - 2011/2// DO - 10.1007/s10450-010-9308-0 VL - 17 IS - 1 SP - 189-199 SN - 1572-8757 KW - Anomalous diffusion KW - Single-file diffusion KW - Nanoporous carbons KW - Simulation KW - Adsorption KW - Molecular dynamics KW - Activated carbons ER - TY - JOUR TI - Photocurable Amphiphilic Perfluoropolyether/Poly(ethylene glycol) Networks for Fouling-Release Coatings AU - Wang, Yapei AU - Betts, Douglas E. AU - Finlay, John A. AU - Brewer, Lenora AU - Callow, Maureen E. AU - Callow, James A. AU - Wendt, Dean E. AU - DeSimone, Joseph M. T2 - MACROMOLECULES AB - We demonstrate a facile way of cross-linking hydrophobic perfluoropolyethers, PFPEs, with a series of hydrophilic poly(ethylene glycol)s, PEGs, to prepare a range of amphiphilic networks for use as fouling-release coatings. The PFPE matrix of the networks endows the coating with a low surface energy while the PEG is added to weaken fouling adhesion. It is therefore envisioned that the coating surfaces of these optically transparent and mechanically robust films will display hydrophobicity leading to nonfouling and fouling release characteristics. Two kinds of functionalized PEG oligomers have been cross-linked with reactive, dimethacryloxy-functionalized PFPE oligomers to form a range of amphiphilic networks: (i) a monomethacryloxy-functionalized PEG macromonomer (454 g/mol) (PEG454−MA) which was used to yield blends with flexible PEG chains on the surface as well as in bulk and (ii) a dimethacryloxy-functionalized PEG (550 g/mol) (PEG550−DMA) which results in PEG chains that are relatively more restricted in the network blends and serve as an added difunctional cross-linker for the network along with the dimethacryloxy-functionalized PFPE. The PFPE/PEG cross-linked networks coated on a substrate show very low swelling characteristics in water when PEG454−MA comprises not more than 10 wt % of the overall composition or when PEG550−DMA is used and does not comprise more than 30 wt % of the overall composition. The PFPE/PEG454−MA coatings having PEG chains with one untethered chain end were found to display relatively high spore and barnacle release performance in comparison to PFPE/PEG550−DMA coatings which have the PEG chains in a more restricted network topology. DA - 2011/2/22/ PY - 2011/2/22/ DO - 10.1021/ma102271t VL - 44 IS - 4 SP - 878-885 SN - 1520-5835 ER - TY - JOUR TI - Generation of a Library of Particles Having Controlled Sizes and Shapes via the Mechanical Elongation of Master Templates AU - Wang, Yapei AU - Merkel, Timothy J. AU - Chen, Kai AU - Fromen, Catherine Ann AU - Betts, Douglas E. AU - DeSimone, Joseph M. T2 - LANGMUIR AB - Herein we describe a versatile and readily scalable approach for the fabrication of particles with a variety of shapes and sizes from a single master template by augmenting the particle replication in nonwetting templates (PRINT) method with mechanical elongation. Repetition of the elongation steps in one direction leads to the fabrication of linear particles with high aspect ratio (AR), over 40 times greater than in the original master, while a range of particle shapes can be obtained by repeating the elongation procedure while changing the stretching direction, generating diamond, rectangular, curved parallelogram particles from a single cubic master. DA - 2011/1/18/ PY - 2011/1/18/ DO - 10.1021/la1045095 VL - 27 IS - 2 SP - 524-528 SN - 0743-7463 ER - TY - JOUR TI - Atmospheric Plasma Treatment of Pre-Electrospinning Polymer Solution: A Feasible Method to Improve Electrospinnability AU - Shi, Quan AU - Vitchuli, Narendiran AU - Nowak, Joshua AU - Lin, Zhan AU - Guo, Bingkun AU - McCord, Marian AU - Bourham, Mohamed AU - Zhang, Xiangwu T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract The electrospinnability of polyethylene oxide (PEO) was manipulated by atmospheric plasma treatment of pre‐electrospinning solutions. Conductivity, viscosity, and surface tension of PEO solutions increased after plasma treatment, and the plasma effect remained longer when the solution concentrate increased. Both untreated and treated solutions were then electrospun, and the morphology of the resultant nanofibers was observed by SEM. Atmospheric plasma treatment improved the electrospinnability of PEO solutions and led to less beads and finer diameter distribution in the resultant nanofibers. Additionally, plasma treatment of the pre‐electrospinning solutions affected the crystal structure of resultant nanofibers. These results suggest that atmospheric plasma treatment is a feasible approach to improve the electrospinnability of polymer solutions and can used to control the structure of electrospun nanofibers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 DA - 2011/1/15/ PY - 2011/1/15/ DO - 10.1002/polb.22157 VL - 49 IS - 2 SP - 115-122 SN - 1099-0488 UR - https://publons.com/publon/3117880/ KW - atmospheric plasma KW - electrospinning KW - fibers KW - melting point KW - nanofibers KW - poly(ethylene oxide) ER - TY - JOUR TI - Allosteric Modulation of Ras-GTP Is Linked to Signal Transduction through RAF Kinase AU - Buhrman, Greg AU - Kumar, V. S. Senthil AU - Cirit, Murat AU - Haugh, Jason M. AU - Mattos, Carla T2 - JOURNAL OF BIOLOGICAL CHEMISTRY AB - Ras is a key signal transduction protein in the cell. Mutants of Gly(12) and Gln(61) impair GTPase activity and are found prominently in cancers. In wild type Ras-GTP, an allosteric switch promotes disorder to order transition in switch II, placing Gln(61) in the active site. We show that the "on" and "off" conformations of the allosteric switch can also be attained in RasG12V and RasQ61L. Although both mutants have similarly impaired active sites in the on state, RasQ61L stabilizes an anti-catalytic conformation of switch II in the off state of the allosteric switch when bound to Raf. This translates into more potent activation of the MAPK pathway involving Ras, Raf kinase, MEK, and ERK (Ras/Raf/MEK/ERK) in cells transfected with RasQ61L relative to RasG12V. This differential is not observed in the Raf-independent pathway involving Ras, phosphoinositide 3-kinase (PI3K), and Akt (Ras/PI3K/Akt). Using a combination of structural analysis, hydrolysis rates, and experiments in NIH-3T3 cells, we link the allosteric switch to the control of signaling in the Ras/Raf/MEK/ERK pathway, supporting a GTPase-activating protein-independent model for duration of the Ras-Raf complex. DA - 2011/2/4/ PY - 2011/2/4/ DO - 10.1074/jbc.m110.193854 VL - 286 IS - 5 SP - 3323-3331 SN - 1083-351X ER - TY - JOUR TI - Transport and Binding Characterization of a Novel Hybrid Particle Impregnated Membrane Material for Bioseparations AU - Herigstad, M. Omon AU - Gurgel, Patrick V. AU - Carbonell, Ruben G. T2 - BIOTECHNOLOGY PROGRESS AB - Abstract The transport and binding properties of a novel hybrid particle‐nonwoven membrane medium are described. In this construct, a polymeric chromatographic resin is entrapped between two layers of a nonwoven polypropylene membrane. The membrane‐supported resin medium offers the advantage of increased interstitial pore diameter to allow passage of cells and other debris in the feed, while providing sufficiently high surface area for product capture within the resin particles. Columns packed with PIM displayed excellent flow distribution and had interstitial porosities of 0.48 ± 0.01, 25–60% larger than those typical of a packed bed. These columns were able to pass over 95% of E. coli cells and human red blood cell concentrate in 30 column volumes while maintaining a pressure drop significantly lower than that of a packed bed with a similar amount of resin. The dynamic binding capacity of bovine serum albumin (BSA) to the chromatographic resin entrapped in the PIM packed column was essentially the same as that observed with the same volume of resin in a packed bed. The General Rate (GR) model of chromatography was used to analyze experiments indicating the breakthrough behavior of the PIM columns is predictable, and very similar to those of a normal packed bed. These results suggest that PIM constructs can be designed to process viscous mobile phases containing particulates while retaining the desirable binding characteristics of the embedded chromatographic resin and could find uses in adsorption separation processes from complex feed streams such as whole blood, cell culture, and food processing. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011 DA - 2011/// PY - 2011/// DO - 10.1002/btpr.502 VL - 27 IS - 1 SP - 129-139 SN - 1520-6033 KW - particle-impregnated membrane KW - process integration KW - mathematical modeling ER - TY - JOUR TI - Synthesis and Characterization of Polymer-Filled Nonwoven Membranes AU - Jung, Kyung-Hye AU - Pourdeyhimi, Behnam AU - Zhang, Xiangwu T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - Abstract Polymer‐filled nonwoven membranes were prepared by filling the open pores of nylon nonwovens with poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PAMPS). PAMPS was synthesized via radical polymerization and crosslinked to prevent its dissolution in water. PAMPS‐filled nylon nonwoven membranes showed enhanced dimensional stability and mechanical properties when compared with PAMPS membranes without nonwovens. The conductivities of PAMPS‐filled nylon nonwovens were slightly lower than those of PAMPS membranes. Compared with PAMPS membranes without nonwoven hosts, both linear and crosslinked PAMPS‐filled nylon nonwoven membranes exhibited lower vapor permeabilities for water, methanol, acetone, and dimethyl methylphophonate (DMMP). In addition, crosslinked PAMPS‐filled nonwoven membranes presented high permselectivity on DMMP over water, which is critical for chemical protection application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 DA - 2011/3/5/ PY - 2011/3/5/ DO - 10.1002/app.32611 VL - 119 IS - 5 SP - 2568-2575 SN - 1097-4628 UR - https://publons.com/publon/7178333/ KW - barrier KW - composites KW - fibers ER - TY - JOUR TI - Signaling pathways that control cell migration: models and analysis AU - Welf, Erik S. AU - Haugh, Jason M. T2 - WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE AB - Abstract Dissecting the intracellular signaling mechanisms that govern the movement of eukaryotic cells presents a major challenge, not only because of the large number of molecular players involved, but even more so because of the dynamic nature of their regulation by both biochemical and mechanical interactions. Computational modeling and analysis have emerged as useful tools for understanding how the physical properties of cells and their microenvironment are coupled with certain biochemical pathways to actuate and control cell motility. In this focused review, we highlight some of the more recent applications of quantitative modeling and analysis in the field of cell migration. Both in modeling and experiment, it has been prudent to follow a reductionist approach in order to characterize what are arguably the principal modules: spatial polarization of signaling pathways, regulation of the actin cytoskeleton, and dynamics of focal adhesions. While it is important that we ‘cut our teeth’ on these subsystems, focusing on the details of certain aspects while ignoring or coarse‐graining others, it is clear that the challenge ahead will be to characterize the couplings between them in an integrated framework. WIREs Syst Biol Med 2011 3 183–190 DOI: 10.1002/wsbm.110. This article is categorized under: Analytical and Computational Methods > Analytical Methods Models of Systems Properties and Processes > Cellular Models Biological Mechanisms > Cell Signaling DA - 2011/// PY - 2011/// DO - 10.1002/wsbm.110 VL - 3 IS - 2 SP - 231-240 SN - 1939-005X ER - TY - JOUR TI - A general set of order parameters for molecular crystals AU - Santiso, Erik E. AU - Trout, Bernhardt L. T2 - JOURNAL OF CHEMICAL PHYSICS AB - Crystallization is fundamental to many aspects of physics and chemistry in addition to being of technological relevance, for example, in the chemical, food, and pharmaceutical industries. However, the design of crystalline materials and crystallization processes is often challenging due to the many variables that can influence the process. As a part of an effort to gain a molecular-level understanding of the way molecules aggregate and organize themselves into crystal structures, in this work we present a new method to construct order parameters suitable for the study of crystallization and polymorph transformations in molecular systems. Our order parameters can be systematically defined for complex systems using information that can be obtained from simple molecular dynamics simulations of the crystals. We show how to construct the order parameters for the study of three different systems: the formation of α-glycine crystals in solution, the crystallization of benzene from the melt, and the polymorph transformation of terephthalic acid. Finally, we suggest how these order parameters could be used to study order-disorder transitions in molecular systems. DA - 2011/2/14/ PY - 2011/2/14/ DO - 10.1063/1.3548889 VL - 134 IS - 6 SP - SN - 1089-7690 ER - TY - JOUR TI - PI3K-dependent cross-talk interactions converge with Ras as quantifiable inputs integrated by Erk (vol 5, pg 246, 2009) AU - Wang, Chun-Chao AU - Cirit, Murat AU - Haugh, Jason M. T2 - MOLECULAR SYSTEMS BIOLOGY DA - 2011/8// PY - 2011/8// DO - 10.1038/msb.2011.61 VL - 7 SP - SN - 1744-4292 ER -