TY - CONF TI - Halozeolites AU - Martin, James AU - Greenwood, K.B. T2 - Gordon Conference on Solid-State Chemistry C2 - 1996/7/14/ CY - Colby-Sawyer College, New London, New Hampshire DA - 1996/7/14/ PY - 1996/7/14/ ER - TY - CONF TI - Metal Halide Analogs of Zeolites AU - Martin, James T2 - 212th National American Chemical Society Meeting C2 - 1996/8/25/ CY - Orlando, FL DA - 1996/8/25/ PY - 1996/8/25/ ER - TY - CHAP TI - Approaches to Synthesis Based on Non-Covalent Bonds AU - Whitesides, G. M. AU - Simanek, E. E. AU - Gorman, C. B. T2 - Chemical Synthesis: Gnosis to Prognosis A2 - Chatgilialoglu, C. A2 - Snieckus, V. T3 - NATO ASI Ser., Ser. E., Applied sciences PY - 1996/// SP - 565–588 PB - Kluwer Academic Publishers SV - No. 320 ER - TY - JOUR TI - Triple-layered orthonaphtho[3.3]orthobenzeno[3.3]orthonaphthophane AU - Mataka, Shuntaro AU - Mitoma, Yoshiharu AU - Sawada, Tsuyoshi AU - Tashiro, Masashi T2 - Tetrahedron Letters AB - Triple-layered [3.3][3.3]orthocyclophane of the anti-type was prepared for the first time, and its structure, in which two naphthalene rings sandwitch one benzene ring, was established by X-ray crystallographic analysis. DA - 1996/1// PY - 1996/1// DO - 10.1016/0040-4039(95)02103-5 VL - 37 IS - 1 SP - 65-68 ER - TY - JOUR TI - Facile synthetic entry into the 1,3-dihydro-3-methyl-3-phenyl-1,2-benziodoxole family of λ3-lodanes AU - Rabah, Ghada A. AU - Koser, Gerald F. T2 - Tetrahedron Letters AB - The synthesis of series of 1,3-dihydro-3-methyl-3-phenyl-1,2-benziodoxoles, 7, containing chloro, tosyloxy, acetoxy, trifluoroacetoxy and azido ligands and the optical resolution of 2-iodo-α-methylbenzhydrol, the starting material for the synthesis of 7, are reported. DA - 1996/9// PY - 1996/9// DO - 10.1016/0040-4039(96)01436-0 VL - 37 IS - 36 SP - 6453-6456 ER - TY - JOUR TI - The Distribution of Standard Rate Constants for Electron Transfer Between Thiol-Modified Gold Electrodes and Adsorbed Cytochrome c AU - Nahir, T.M. AU - Bowden, E.F. T2 - Journal of Electroanalytical Chemistry AB - The magnitude of the total rate constant of an electrochemical reaction at small overpotentials is shown to depend on the exponentials of the distance between the electron donor and acceptor, the reorganization energy, and the formal potential of the reaction. When a population distribution of one or more of these three parameters exists, the effect on the measured standard rate constant can be illuminated by using small-amplitude a.c. electrochemical impedance spectroscopy. Assuming a Gaussian distribution of the logarithm of the standard rate constants, the results from the system of cytochrome c molecules adsorbed on thiol-modified gold electrodes yield a standard deviation of approximately 0.5 for log k°/kavg°. The peak broadening of reversible voltammograms is related to a comparable distribution of formal potentials. DA - 1996/// PY - 1996/// DO - 10.1016/0022-0728(96)04551-2 VL - 410 SP - 9-13 KW - cytochrome c KW - thiol-modified gold electrodes KW - electron transfer KW - rate constants ER - TY - JOUR TI - Defect metastability associated with oxygen and nitrogen impurity atoms in hydrogenated amorphous silicon films AU - Lucovsky, G. AU - Jing, Z. T2 - Journal of Non-Crystalline Solids AB - A new mechanism for charged-carrier-trapping-induced defect metastability that can take place in hydrogenated amorphous silicon alloys containing oxygen and/or nitrogen alloy atoms is described. The experimental results that prompted the study of this type of defect metastability mechanism were differences in the Staebler-Wronski effect in hydrogenated amorphous silicon nitrogen alloys prepared from N2 and NH3 source gases by remote plasma-enhanced chemical-vapor deposition. DA - 1996/5// PY - 1996/5// DO - 10.1016/0022-3093(95)00700-8 VL - 198-200 SP - 342-346 J2 - Journal of Non-Crystalline Solids LA - en OP - SN - 0022-3093 UR - http://dx.doi.org/10.1016/0022-3093(95)00700-8 DB - Crossref ER - TY - JOUR TI - Theory of chemisorption and reactions on metal surfaces AU - Whitten, J T2 - Surface Science Reports AB - A review of theoretical methods used to describe chemisorption and adsorbate reactions on metal surfaces is contained in this report. A comprehensive perspective on state-of-the-art electronic structure methods suitable for these problems and a review of applications that illustrate current capabilities of theory are presented. First-principles ab initio and density functional methods and semiempirical approaches that permit the calculation of adsorbate energetics, structure and spectra are emphasized. In addition to the chemisorption of molecules and molecular fragments, applications include gas-surface reactions, dissociative processes and surface reactions involving coadsorbed species. Many of the applications are relevant to transition metal heterogeneous catalysis. Both slab and atomic cluster methods are described. Methods are critiqued, with reference to published applications, to illustrate capabilities and limitations of different approaches. An extensive compendium of applications is included. DA - 1996/// PY - 1996/// DO - 10.1016/0167-5729(96)80004-5 VL - 24 IS - 3-4 SP - 55-124 J2 - Surface Science Reports LA - en OP - SN - 0167-5729 UR - http://dx.doi.org/10.1016/0167-5729(96)80004-5 DB - Crossref ER - TY - JOUR TI - Chemisorption of CNH2 and HCNH on the Ni(111) surface AU - Yang, Hong AU - Whitten, Jerry L. T2 - Chemical Physics Letters AB - The chemisorption of CNH2 and HCNH on Ni(111) is studied using an ab initio configuration interaction embedding theory. Both CNH2 and HCNH strongly bind to the Ni(111) surface with HCNH more stable by 31.7 kcal/mol. CNH2 is adsorbed at a bridge site via the C atom. Both C and N atoms in HCNH are involved in bonding to the surface with the C-N bond parallel to the surface. The calculated CN stretching frequencies and bond lengths are 1335 cm−1 and 1.32 Å for CNH2 and 1457 cm−1 and 1.32 Å for HCNH, respectively. DA - 1996/3// PY - 1996/3// DO - 10.1016/0009-2614(96)00065-6 VL - 251 IS - 1-2 SP - 20-25 J2 - Chemical Physics Letters LA - en OP - SN - 0009-2614 UR - http://dx.doi.org/10.1016/0009-2614(96)00065-6 DB - Crossref ER - TY - JOUR TI - Theoretical Adsorption Studies of HCN and HNC on Ni(111) AU - Yang, Hong AU - Whitten, Jerry L. T2 - The Journal of Physical Chemistry AB - The interaction of hydrogen cyanide (HCN) and hydrogen isocyanide (HNC) with Ni(111) is studied by using ab initio embedding theory. The Ni(111) surface is modeled as a three-layer, 28-atom cluster with the Ni atoms fixed at bulk lattice sites. The present calculations show that both HCN and HNC bind to the surface in an end-on geometry with the molecular axis perpendicular to the surface. Tilting either the H atom or the H−C bond or the H−N bond away from the surface normal destabilizes the system. The side-on bonded HCN and HNC with the C−N bond parallel to the surface are energetically less stable than the corresponding end-on bonded species. The calculated adsorption energy of the end-on HCN is 18 kcal/mol with the fcc 3-fold site favored over other sites by about 1−3 kcal/mol. The end-on HNC binds to the surface at the atop site with adsorption energy of 11 kcal/mol. The calculated adsorption energy for the side-on bonded HCN is only 7 kcal/mol. The side-on bonded HNC species is found to be unbound by 12 kcal/mol on Ni(111). Calculated C−N stretching frequencies are 2200 cm-1 and 2100 cm-1 for end-on bonded HCN and HNC and 2105 cm-1 and 1530 cm-1 for the side-on bonded HCN and HNC, respectively. Dipole moment calculations show that the bonding of HCN to the surface is relatively more ionic than HNC. DA - 1996/1/1/ PY - 1996/1/1/ DO - 10.1021/jp953238w VL - 100 IS - 12 SP - 5090-5097 J2 - J. Phys. Chem. LA - en OP - SN - 0022-3654 1541-5740 UR - http://dx.doi.org/10.1021/jp953238w DB - Crossref ER - TY - CONF TI - Radical-Substituted Alkanethiol Monolayers: Toward Molecule-Based Multilayer Magnetic Materials AU - Schultz, D T2 - Hoechst-Celanese Polymer Workshop C2 - 1996/10/28/ DA - 1996/10/28/ PY - 1996/10/28/ ER - TY - CONF TI - Semiquinones as Building Blocks for Molecular Magnets AU - Shultz, D T2 - International Conference on Molecule-Based Magnetism C2 - 1996/7/18/ DA - 1996/7/18/ PY - 1996/7/18/ ER - TY - CONF TI - Preparation of Paramagnetic Ligands for Coordination-Complexes and Networks With Interesting Magnetic Properties AU - Schultz, D T2 - Molecule-Based Magnetism Conference C2 - 1996/7/15/ CY - Osaka, Japan DA - 1996/7/15/ PY - 1996/7/15/ ER - TY - CONF TI - Preparation and Characterization of Conjugated Polymers with Semiquinone Repeat Units AU - Schultz, D AU - Hollomon, M T2 - 212th National ACS Meeting C2 - 1996/// CY - Orlando, FL DA - 1996/// PY - 1996/8/25/ ER - TY - CONF TI - Preparation and Characterization of a Nitroxide-Substituted Metalloporphyrin AU - Schultz, D.A. AU - Gwaltney, K.P. T2 - 212th National ACS Meeting C2 - 1996/// CY - Orlando, FL DA - 1996/// PY - 1996/8/25/ ER - TY - BOOK TI - Introduction to Spectroscopy AU - Pavia, D.L. AU - Lampman, G.M. AU - Kriz, G.S. A3 - Schultz, D. DA - 1996/// PY - 1996/// ET - 2nd PB - Harcourt Brace College Publishers ER - TY - JOUR TI - Analysis of Double-stranded Polymerase Chain Reaction Products from the Bacillus cereus Group by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry AU - Wunschel, D.S. AU - Fox, K.F. AU - Fox, A. AU - Bruce, J.E. AU - Muddiman, D.C. AU - Smith, R.D. T2 - Rapid Communications in Mass Spectrometry DA - 1996/// PY - 1996/// VL - 10 IS - 1 SP - 29–35 ER - TY - JOUR TI - Characterization of PCR Products from Bacilli Using Electrospray Ionization FTICR Mass Spectrometry AU - Muddiman, David C. AU - Wunschel, David S. AU - Liu, Chuanliang AU - Paša-Tolić, Ljiljana AU - Fox, Karen F. AU - Fox, Alvin AU - Anderson, Gordon A. AU - Smith, Richard D. T2 - Analytical Chemistry AB - A procedure for rapid purification of polymerase chain reaction (PCR) products allowing precise molecular weight determination using electrospray ionization-Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry is described. PCR amplification utilized the DNA polymerase from Pyrococcus furiosus (Pfu) which, unlike Taq, does not incorporate a nontemplated terminal deoxyadenosine phosphate. An 89-base pair nucleotide portion of the spacer region between the 16S and 23S ribosomal rRNA genes was amplified from the genome of three members of Bacillus cereus group and a 114 nucleotide region from the Bacillus subtilis. PCR involves polymerization of nucleotide precursors using two oligonucleotide primers and an amplification enzyme, as well as the presence of metal ions. Mass spectrometric analysis greatly benefits from removal of the oligonucleotide primers (15- and 17-mers in this instance) and nucleotide precursors since they adversely affect sensitivity and metal ion adduction results in an inaccurate molecular weight determination. In the presence of guanidinium hydrochloride, the PCR products bind preferentially to a silica resin, allowing removal of other components (i.e., dNTP's, primers, and salts). Further removal of metal ions was accomplished using a microdialysis device, allowing samples to be pumped through a hollow cellulose fiber with an external countercurrent flow of 2.5 mM ammonium acetate. Prior to injection into the mass spectrometer, the sample buffer was adjusted to 50 vol % acetonitrile, 25 mM piperidine, and 25 mM imidazole, which enhanced signal intensity. The molecular weights of the PCR products determined by nucleotide sequence and MS analysis were in excellent agreement, and several PCR products were analyzed where mass differences corresponding to single base substitutions could be accurately assigned. These assignments were possible due to the high mass precision, accuracy, and resolution FTICR inherently affords. This constitutes the first report demonstrating the ionization and detection of PCR products by mass spectrometry with mass precision and accuracy for assigment of such modifications or substitutions. DA - 1996/1// PY - 1996/1// DO - 10.1021/ac960689j VL - 68 IS - 21 SP - 3705-3712 J2 - Anal. Chem. LA - en OP - SN - 0003-2700 1520-6882 UR - http://dx.doi.org/10.1021/ac960689j DB - Crossref ER - TY - JOUR TI - Preparation and characterization of a bis-galvinoxyl-disulfide AU - Shultz, David A. AU - Zhao, Qi T2 - Tetrahedron Letters AB - Abstract The synthesis of a biradical disulfide is described. This biradical exhibits an EPR spectrum consistent with ¦ J ¦>> a . Cyclic voltammetry of monolayers of this biradical shows that the radical monolayer exhibits less pH-dependence than its phenol counterpart. DA - 1996/12// PY - 1996/12// DO - 10.1016/s0040-4039(96)02067-9 VL - 37 IS - 49 SP - 8837-8840 J2 - Tetrahedron Letters LA - en OP - SN - 0040-4039 UR - http://dx.doi.org/10.1016/s0040-4039(96)02067-9 DB - Crossref ER - TY - JOUR TI - Design and Self-Assembly of Nanoscale Organoplatinum Macrocycles AU - Manna, Joseph AU - Whiteford, Jeffery A. AU - Stang, Peter J. AU - Muddiman, David C. AU - Smith, Richard D. T2 - Journal of the American Chemical Society AB - ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDesign and Self-Assembly of Nanoscale Organoplatinum MacrocyclesJoseph Manna, Jeffery A. Whiteford, Peter J. Stang, David C. Muddiman, and Richard D. SmithView Author Information Department of Chemistry, University of Utah Salt Lake City, Utah 84112 Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland, Washington 99352Cite this: J. Am. Chem. Soc. 1996, 118, 36, 8731–8732Publication Date (Web):September 11, 1996Publication History Received17 June 1996Published online11 September 1996Published inissue 1 January 1996https://doi.org/10.1021/ja962041uCopyright © 1996 American Chemical SocietyRequest reuse permissionsArticle Views686Altmetric-Citations78LEARN 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 Read OnlinePDF (205 KB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Hydrogen,Ions,Macrocycles,Nanoscale,Self organization Get e-Alerts DA - 1996/1// PY - 1996/1// DO - 10.1021/ja962041u VL - 118 IS - 36 SP - 8731-8732 J2 - J. Am. Chem. Soc. LA - en OP - SN - 0002-7863 1520-5126 UR - http://dx.doi.org/10.1021/ja962041u DB - Crossref ER - TY - JOUR TI - A Quantitative Study ofin vitroHepatic Metabolism of Tacrolimus (FK506) Using Secondary Ion and Matrix-assisted Laser Desorption/Ionization Mass Spectrometry AU - Gusev, Arkady I. AU - Muddiman, David C. AU - Proctor, Andrew AU - Sharkey, Andrew G. AU - Tata, Prasad N. V. AU - Venkataramanan, Raman AU - Hercules, David M. T2 - Rapid Communications in Mass Spectrometry AB - The identification and simultaneous quantification of Tacrolimus and its hepatic metabolites in baboons has been achieved using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry and static secondary-ion mass spectrometry (TOF-SIMS). Little fragmentation, high sensitivity and tolerance to contamination are the major advantages of these methods, allowing facile identification and quantification of metabolites produced in vitro with minor analyte isolation. Based on the MALDI and TOF-SIMS results, seven metabolites have been identified: de-methylated, di de-methylated, hydroxylated, di hydroxylated, de-methylated hydroxylated, dihydrodiol, and di de-methylated hydroxylated. The concentrations of the parent drug and its major metabolites (e.g. de-methylated, di de-methylated) were measured using Rapamycin as an internal standard. The time course of Tacrolimus and its major metabolites as a function of incubation time was calculated. Good correlation between SIMS and MALDI results was obtained. DA - 1996/7/31/ PY - 1996/7/31/ DO - 10.1002/(sici)1097-0231(19960731)10:10<1215::aid-rcm647>3.0.co;2-k VL - 10 IS - 10 SP - 1215-1218 J2 - Rapid Commun. Mass Spectrom. LA - en OP - SN - 0951-4198 1097-0231 UR - http://dx.doi.org/10.1002/(sici)1097-0231(19960731)10:10<1215::aid-rcm647>3.0.co;2-k DB - Crossref ER - TY - JOUR TI - Charge-state reduction with improved signal intensity of oligonucleotides in electrospray ionization mass spectrometry AU - Muddiman, David C. AU - Cheng, Xueheng AU - Udseth, Harold R. AU - Smith, Richard D. T2 - Journal of the American Society for Mass Spectrometry AB - The shift of charge states of oligonucleotide negative ions formed in electrospray ionization mass spectrometry to higher mass-to-charge ratio has been accomplished by addition of organic acids and bases to the solution to be electrosprayed. The use of acetic acid or formic acid combined with piperidine and imidazole effectively reduced charge states. Signal intensity and stability were enhanced greatly when the infused solution contained a high percentage of acetonitrile. In addition, the cocktail that contained imidazole, piperidine, and acetic acid in 80% acetonitrile not only reduced charge states, but also substantially suppressed Na adduction. Several oligonucleotides that varied in base composition and length were investigated, and studies of mixtures showed a significant reduction in spectral complexity. DA - 1996/8// PY - 1996/8// DO - 10.1016/1044-0305(96)80516-2 VL - 7 IS - 8 SP - 697-706 J2 - J Am Soc Mass Spectrom LA - en OP - SN - 1044-0305 1879-1123 UR - http://dx.doi.org/10.1016/1044-0305(96)80516-2 DB - Crossref ER - TY - JOUR TI - Enhancement of ion intensity in time-of-flight secondary-ionization mass spectrometry AU - Nicola, Anthony J. AU - Muddiman, David C. AU - Hercules, David M. T2 - Journal of the American Society for Mass Spectrometry AB - Enhancement of ion intensity in static secondary-ionization mass spectrometry (SIMS) has been achieved by using a matrix-assisted sample preparation technique. Previous investigations of polymers and biomolecules by SIMS indicated that secondary-ion (SI) yield is dependent on substrate coverage. Recently we discovered a sample preparation technique that enhanced the SI yield of cyclosporin A (CsA) in an allograft patient sample and neat samples of CsA (1202 u) and polystyrene (M w=2650 u). The preparation technique involves deposition of a submonolayer of cocaine hydrochloride (5 µL of a 20-µg/mL MeOH solution) on an etched silver substrate, solvent evaporation, and subsequent deposition of the analyte. This preparation method resulted in ∼300% increase in the SI yield of CsA and polystyrene when deposited from neat solutions. The original discovery was observed when a blood extract that contained CsA was deposited on an etched Ag substrate that had been soaking in a dilute cocaine solution for ∼2 months. In these initial experiments, the SI yield of CsA was enhanced by over 1 order of magnitude. DA - 1996/5// PY - 1996/5// DO - 10.1016/1044-0305(96)00006-2 VL - 7 IS - 5 SP - 467-472 J2 - J Am Soc Mass Spectrom LA - en OP - SN - 1044-0305 1879-1123 UR - http://dx.doi.org/10.1016/1044-0305(96)00006-2 DB - Crossref ER - TY - JOUR TI - Important Aspects concerning the Quantification of Biomolecules by Time-of-Flight Secondary-Ion Mass Spectrometry AU - Muddiman, David C. AU - Nicola, Anthony J. AU - Proctor, Andrew AU - Hercules, David M. T2 - Applied Spectroscopy AB - Fundamental aspects regarding the use of time-of-flight secondary-ion mass spectrometry (TOF-SIMS) as a quantitative tool for the analysis of organic compounds are reported. The following factors are discussed: (1) the use of Poisson's law to correct for dead-time in single-ion data collection; (2) practical considerations concerning the analysis of “real world” samples; and (3) the effect of the etching process on the reproducibility of the intensity ratio (analyte/internal standard) of Ag-cationized species. To evaluate the importance of these factors, we used cocaine and cyclosporin A (CsA) as analytes because they show protonated and Ag-cationized species, respectively, in their SIMS spectra. Correction for detector dead-time using Poisson's law of single-ion counting expanded the dynamic range for cocaine by ∼2 orders of magnitude. For analyses requiring only a small dynamic range (i.e., CsA), the correction improved the % RSD of the slope from 2.43 to 0.87%. The maximum secondary-ion (SI) yield of CsA (Ag-cationized species) occurs at a CsA concentration ∼3 orders of magnitude higher than the therapeutic levels in blood (25–2000 ng/mL). It is discussed how this problem should be addressed. Analysis of variance (ANOVA) indicates that Ag substrates must be etched under identical conditions to obtain quantitative results when species requiring cationization are being analyzed. DA - 1996/2// PY - 1996/2// DO - 10.1366/0003702963906410 VL - 50 IS - 2 SP - 161-166 J2 - Appl Spectrosc LA - en OP - SN - 0003-7028 1943-3530 UR - http://dx.doi.org/10.1366/0003702963906410 DB - Crossref KW - SIMS KW - quantification KW - mass spectrometry KW - TOF-SIMS ER - TY - JOUR TI - Direct quantification of cocaine in urine by time-of-flight mass spectrometry AU - Muddiman, David C. AU - Gusev, Arkady I. AU - Martin, Lee B. AU - Hercules, David M. T2 - Fresenius' Journal of Analytical Chemistry DA - 1996/1/1/ PY - 1996/1/1/ DO - 10.1007/s002169600017 VL - 354 IS - 1 SP - 103-110 J2 - Fresenius' Journal of Analytical Chemistry OP - SN - 0937-0633 1432-1130 UR - http://dx.doi.org/10.1007/s002169600017 DB - Crossref ER - TY - JOUR TI - The Novel Encapsulation of Transition Metals in a Bioctahedral Rare Earth Metal Cluster: Cs2La10I17Co2 AU - Lulei, Michael AU - Maggard, Paul A. AU - Corbett, John D. T2 - Angewandte Chemie International Edition in English AB - A missing link in the chemistry of rare earth metal cluster compounds stabilized by interstitial transition metals is the new La10Co2 dimeric cluster shown on the right with its iodine environment. The most remarkable structural features of this cluster are the two edge-sharing La octahedra, each centered by a Co atom. DA - 1996/8// PY - 1996/8// DO - 10.1002/anie.199617041 VL - 35 IS - 15 SP - 1704-1706 J2 - Angew. Chem. Int. Ed. Engl. LA - en OP - SN - 0570-0833 1521-3773 UR - http://dx.doi.org/10.1002/anie.199617041 DB - Crossref KW - clusters KW - rare earth metal compounds KW - solid-state structures ER - TY - JOUR TI - In situobservations of NOy, O3, and the NOy/O3ratio in the lower stratosphere AU - Fahey, D. W. AU - Donnelly, S. G. AU - Keim, E. R. AU - Gao, R. S. AU - Wamsley, R. C. AU - Del Negro, L. A. AU - Woodbridge, E. L. AU - Proffitt, M. H. AU - Rosenlof, K. H. AU - Ko, M. K. W. AU - Weisenstein, D. K. AU - Scott, C. J. AU - Nevison, C. AU - Solomon, S. AU - Chan, K. R. T2 - Geophysical Research Letters AB - Extensive in situ measurements of reactive nitrogen (NO y ) and ozone (O 3 ) were made in the lower stratosphere over a broad latitude range (60°N–70°S) during two different seasons (March and October) in 1994. Both NO y and O 3 mixing ratios show a strong latitude dependence, with values increasing toward the poles. The NO y /O 3 ratio reveals a high‐gradient region near the tropics that is not well‐represented in standard 2‐D photochemical transport models. Improving the representation by changing the horizontal eddy‐diffusion coefficients near the tropics has important implications for the predicted impacts of aircraft emissions on stratospheric O 3 . DA - 1996/6/15/ PY - 1996/6/15/ DO - 10.1029/96gl01476 VL - 23 IS - 13 SP - 1653-1656 J2 - Geophys. Res. Lett. LA - en OP - SN - 0094-8276 UR - http://dx.doi.org/10.1029/96gl01476 DB - Crossref ER - TY - JOUR TI - Two new examples for the unusual R12L17z2-structure type: La12i17fe2 and ce12i17mn2 AU - Lulei, M. AU - Martin, J.D. AU - Corbett, J.D. T2 - Journal of Solid State Chemistry AB - Reactions of KI, La, LaI3, and Fe in niobium tubes at 900°C yield black crystals of La12I17Fe2which were characterized by single-crystal X-ray diffraction (triclinic,P1,Z= 1,a= 11.967(8),b= 11.851(6),c= 9.918(7) Å, α = 114.59(5)°, β = 104.83(6)°, γ = 93.05(5)°,R(F)/Rw= 3.8/4.3%). Similar experiments also gave the isostructural Ce12I17Mn2according to the Guinier powder pattern (a= 11.863(6),b= 11.840(6),c= 9.857(5) Å, α = 14.90(4)°, β = 104.47(4)°, γ = 93.28(4)°). The Pr12I17Fe2-type structure contains octahedral rare-earth-metal cluster units R6centered by a transition-metal atomZand sheathed by iodine atoms. These are closely linked by seven Ii−iand one Ii−a−abridges that lead to the unusually low I:Pr ratio for phases with isolated clusters. The compounds reported here together with Pr12I17Z2,Z= Fe, Re are the only phases known to adopt this structure type. The La12I17Fe2phase formally has 17.5eper cluster, and its magnetic susceptibility data are consistent with equal numbers of 17-eand 18-e(closed shell) clusters, with μ = 1.11 BM for the former. DA - 1996/// PY - 1996/// DO - 10.1006/jssc.1996.0293 VL - 125 IS - 2 SP - 249-254 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0000979890&partnerID=MN8TOARS ER - TY - JOUR TI - β-Mn(O2CMe)2: Solvothermal synthesis and crystal structure of an unprecedented three-dimensional manganese(II) network AU - Martin, J.D. AU - Hess, R.F. T2 - Chemical Communications DA - 1996/// PY - 1996/// IS - 21 SP - 2419-2420 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0003780601&partnerID=MN8TOARS ER - TY - JOUR TI - Observations of large reductions in the NO/NOyratio near the mid-latitude tropopause and the role of heterogeneous chemistry AU - Keim, E. R. AU - Fahey, D. W. AU - Negro, L. A. Del AU - Woodbridge, E. L. AU - Gao, R. S. AU - Wennberg, P. O. AU - Cohen, R. C. AU - Stimpfle, R. M. AU - Kelly, K. K. AU - Hintsa, E. J. AU - Wilson, J. C. AU - Jonsson, H. H. AU - Dye, J. E. AU - Baumgardner, D. AU - Kawa, S. R. AU - Salawitch, R. J. AU - Proffitt, M. H. AU - Loewenstein, M. AU - Podolske, J. R. AU - Chan, K. R. T2 - Geophysical Research Letters AB - During the 1993 NASA Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE), anomalously low nitric oxide (NO) was found in a distinct sunlit layer located above the mid‐latitude tropopause. The presence of a significant amount of reactive nitrogen (NO y ) in the layer implies the systematic removal of NO, which is without precedent in stratospheric in situ observations. Large increases in measured chlorine monoxide (ClO) and the hydroperoxyl radical (HO 2 ) also were observed in the layer. Heterogeneous reaction rate constants of chlorine nitrate (ClONO 2 ) with hydrogen chloride (HCl) and H 2 O to form nitric acid (HNO 3 ) on sulfate aerosol are enhanced in the NO removal layer by local increases in H 2 O and aerosol surface area. The associated conversion of NO x (= NO + NO 2 ) to HNO 3 is the most likely cause of the observed low NO and NO x /NO y values and high ClO values. DA - 1996/11/1/ PY - 1996/11/1/ DO - 10.1029/96gl02593 VL - 23 IS - 22 SP - 3223-3226 ER - TY - JOUR TI - In-situ observations of an Antarctic polar stratospheric cloud: Similarities with Arctic observations AU - Dye, J. E. AU - Baumgardner, D. AU - Gandrud, B. W. AU - Drdla, K. AU - Barr, K. AU - Fahey, D. W. AU - Delnegro, L. A. AU - Tabazadeh, A. AU - Jonsson, H. H. AU - Wilson, J. C. AU - Loewenstein, M. AU - Podolske, J. R. AU - Chan, K. R. T2 - Geophysical Research Letters AB - Measured particle volumes in a type I polar stratospheric cloud near the Antarctic polar vortex during ASHOE/MAESA show that the onset of the cloud occurred near 193 K, 3 degrees colder than nitric acid trihydrate (NAT) saturation. The onset temperature, the smooth increase of volume with decreasing temperature, the inverse correlation of particle volume and enhanced NO y (HNO 3 in the particles) with temperature, and comparisons of observations with an equilibrium model of ternary droplet growth all support the notion that much of this type I PSC was ternary solution droplets. This provides confirmation of previous findings in the northern hemisphere. However, the ternary model does not fit the observations in all regions. This may be due to the presence of some solid phase growth in agreement with impactor observations. DA - 1996/7// PY - 1996/7// DO - 10.1029/96gl01812 VL - 23 IS - 15 SP - 1913-1916 ER - TY - JOUR TI - Photodriven Electron and Energy Transfer from Copper Phenanthroline Excited States AU - Ruthkosky, M. AU - Castellano, F.N. AU - Meyer, G.J. T2 - Inorganic Chemistry DA - 1996/// PY - 1996/// VL - 35 IS - 22 SP - 6406-6412 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0000482638&partnerID=MN8TOARS ER - TY - BOOK TI - Light-induced processes in molecular gel materials AU - Castellano, F.N. AU - Meyer, G.J. DA - 1996/// PY - 1996/// VL - 44 SE - 167-208 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-53249100834&partnerID=MN8TOARS ER - TY - JOUR TI - EPR Linewidth (T2) Method to Measure Oxygen Permeability of Phospholipid Bilayers and Its Use to Study the Effect of Low Ethanol Concentrations AU - Smirnov, Alex I. AU - Clarkson, R.B. AU - Belford, R.L. T2 - Journal of Magnetic Resonance, Series B AB - It is well known that continuous-wave EPR spectra of nitroxide probes (labels) introduced into phospholipid bilayers are sensitive to molecular oxygen. However, accurate determination of oxygen broadening from these experiments is complicated by the complex shapes of EPR spectra, which are strongly influenced by anisotropic restricted motion of the probe molecules. An accurate method is presented to extract the oxygen broadening from the spectra measured with and without oxygen and at the same temperature. The method is based on a fast convolution algorithm with Levenberg–Marquardt optimization. This method was previously applied to EPR oximetry with nitroxides exhibiting rotational motion in the fast limit. It is shown that for several membrane spin probes, the oxygen broadening can be described as homogeneous; thus, a one-linewidth-parameter fitting model is appropriate. The method is applied to measure permeability profiles of model membranes composed from 1,2-dimyristoyl-sn-glycero-3-phosphocholine above and below the main phase transition. For both membrane phases, the broadening of doxyl- and sterol-type labels is found to be homogeneous, a finding consistent with the model of Heisenberg exchange between molecular oxygen and spin probes. As an example, the method is applied to study the ethanol effect on local oxygen permeability of a phospholipid bilayer. It is shown that ethanol concentrations as low as 1% (v/v) increase oxygen permeability of the bilayer. The effect is larger at the surface of the membrane than at its center, indicating that ethanol molecules interact primarily within the polar head region of the bilayer. DA - 1996/5// PY - 1996/5// DO - 10.1006/jmrb.1996.0073 VL - 111 IS - 2 SP - 149-157 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0030139747&partnerID=MN8TOARS ER - TY - JOUR TI - Synthesis of a series of focally-substituted organothiol dendrons AU - CHEN, KY AU - GORMAN, CB T2 - JOURNAL OF ORGANIC CHEMISTRY DA - 1996/// PY - 1996/// VL - 61 IS - 26 SP - 9229-9235 ER - TY - JOUR TI - Platinum-Catalyzed Oxidations of Organic Compounds by Ferric Sulfate: Use of a Redox Fuel Cell to Mediate Complete Oxidation of Ethylene Glycol by Dioxygen at 80°C AU - Gorman, C.B. AU - Bergens, S.H. AU - Whitesides, G.M. T2 - Journal of catalysis AB - A number of alcohols, aldehydes, and carboxylic acids were oxidized under mild conditions (60–80°C, 3MH2SO4in water) by Fe(III) using a catalytic amount of Pt black to generate Fe(II) and protons. The extent of oxidation depended on the structures of the organic reductant and on reaction conditions. A redox fuel cell that catalyzed the complete oxidation of ethylene glycol by dioxygen at 80°C was assembled. Fe(II) generated by oxidation of ethylene glycol was reoxidized to Fe(III) at the anode of the cell. A V(V)/V(IV)/HNO3/O2redox system was used to catalyze the electrochemical reduction of dioxygen. Both the anode and cathode consisted of WDF graphite felt, the surface of which had been oxidized by boiling concentrated nitric acid for 15 min. A maximum power density of 9.9 mW/cm3of graphite felt was obtained at a cell voltage of 197 mV. DA - 1996/1// PY - 1996/1// DO - 10.1006/jcat.1996.0009 VL - 158 IS - 1 SP - 92–96 SN - 0021-9517 ER - TY - JOUR TI - Dynamic Electrochemistry:  Methodology and Application AU - Anderson, James L. AU - Bowden, Edmond F. AU - Pickup, Peter G. T2 - Analytical Chemistry AB - ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTDynamic Electrochemistry: Methodology and ApplicationJames L. Anderson, Edmond F. Bowden, and Peter G. PickupView Author Information Department of Chemistry, University of Georgia, Athens, Georgia 30602 Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695 Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3X7 Cite this: Anal. Chem. 1996, 68, 12, 379–444Publication Date (Web):June 15, 1996Publication History Published online15 June 1996Published inissue 1 January 1996https://doi.org/10.1021/a1960015yCopyright © 1996 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views3716Altmetric-Citations84LEARN 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 Read OnlinePDF (763 KB) Get e-AlertsSUBJECTS:Adsorption,Electrodes,Gold,Peptides and proteins,Redox reactions Get e-Alerts DA - 1996/1// PY - 1996/1// DO - 10.1021/a1960015y VL - 68 IS - 12 SP - 379-444 J2 - Anal. Chem. LA - en OP - SN - 0003-2700 1520-6882 UR - http://dx.doi.org/10.1021/a1960015y DB - Crossref ER - TY - JOUR TI - Diffusionless Electrochemistry of Cytochromeb5Adsorbed on a Multilayer Film Electrode AU - Glenn, Julie D. H. AU - Bowden, Edmond F. T2 - Chemistry Letters AB - Abstract A multilayer film electrode has been developed that is well-suited for diffusionless electron transfer studies of acidic proteins. The multilayer electrode is comprised of trypsin-solubilized cytochrome b5 adsorbed electrostatically to a self-assembled HO2C(CH2)7SH/gold substrate via an intervening bridging layer of cationic poly-l-lysine. DA - 1996/5// PY - 1996/5// DO - 10.1246/cl.1996.399 VL - 25 IS - 5 SP - 399-400 J2 - Chem. Lett. LA - en OP - SN - 0366-7022 1348-0715 UR - http://dx.doi.org/10.1246/cl.1996.399 DB - Crossref ER - TY - JOUR TI - Hedging with crop yield futures: A mean-variance analysis AU - Vukina, T AU - Li, DF AU - Holthausen, DM T2 - AMERICAN JOURNAL OF AGRICULTURAL ECONOMICS AB - Abstract This investigation into the use of new Chicago Board of Trade yield futures to manage price and yield risks shows that a risk‐minimizing firm can reduce its variance of profit by hedging in both markets compared to hedging in price futures only. The greater the variance of the contract underlying yield, the less effective the two‐instrument hedge. Hedging effectiveness of the dual strategy also depends on the price and yield bases, and the effect of a change in either basis depends on whether the established crop yield futures position is short or long. DA - 1996/11// PY - 1996/11// DO - 10.2307/1243857 VL - 78 IS - 4 SP - 1015-1025 SN - 0002-9092 KW - hedging KW - price and yield uncertainty KW - yield futures contracts ER - TY - JOUR TI - Efficiency gains in broiler production through contract parameter fine tuning AU - Vukina, T AU - Foster, WE T2 - POULTRY SCIENCE AB - This paper reports on an analysis of existing broiler production contracts, with an attempt to establish the degree of efficiency gains possible from contract alteration. With the use of settlement cost and farm level data, an assessment is made of optimal grower input decisions given contract specifications. Using this analytical framework, alternative contract designs are simulated by searching over possible contract parameter values. The foci of the analysis are three contract parameters: base payment, bonus factor, and the utilities cost allocation factor. In the first two cases, the simulation generated ambiguous results. In the third case, results seem to indicate that switching part of the electricity cost from the grower's cost into the settlement cost may result in a mutual welfare gain. DA - 1996/11// PY - 1996/11// DO - 10.3382/ps.0751351 VL - 75 IS - 11 SP - 1351-1358 SN - 0032-5791 KW - economic optimization KW - broiler production KW - contracts KW - growers' payments ER - TY - PAT TI - Method of making asymmetric DE ring intermediates for the synthesis of camptothecin and camptothecin analogs AU - Comins, D. L. C2 - 1996/// DA - 1996/// PY - 1996/// ER - TY - PAT TI - Method of making asymmetric DE ring intermediates for the synthesis of camptothecin analogs AU - Comins, D. L. C2 - 1996/// DA - 1996/// PY - 1996/// ER - TY - JOUR TI - Soluble synthetic multiporphyrin arrays .2. Photodynamics of energy-transfer processes AU - Hsiao, JS AU - Krueger, BP AU - Wagner, RW AU - Johnson, TE AU - Delaney, JK AU - Mauzerall, DC AU - Fleming, GR AU - Lindsey, JS AU - Bocian, DF AU - Donohoe, RJ T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY AB - Soluble ethyne-linked tetraarylporphyrin arrays that mimic natural light-harvesting complexes by absorbing light and directing excited-state energy have been investigated by static and time-resolved absorption and fluorescence spectroscopies. Of particular interest is the role of the diarylethyne linkers in mediating energy transfer. The major conclusions from this study, which is limited to the examination of arrays containing Zn and free-base (Fb) porphyrins, include the following: (1) Singlet excited-state energy transfer from the Zn porphyrin to the Fb porphyrin is extremely efficient (95−99%). Competitive electron-transfer reactions are not observed. (2) The rate of energy transfer is slowed up to 4-fold by the addition of groups to the linker that limit the ability of the linker and porphyrin to adopt geometries tending toward coplanarity. Thus, the mechanism of energy transfer predominantly involves through-bond communication via the linker. Consistent with this notion, the measured lifetimes of the Zn porphyrin in the dimers at room temperature yield energy-transfer rates ((88 ps)-1 < ktrans < (24 ps)-1) that are significantly faster than those predicted by the Förster (through-space) mechanism ((720 ps)-1). Nevertheless, the electronic communication is weak and the individual porphyrins appear to retain their intrinsic radiative and non-radiative rates upon incorporation into the arrays. (3) Transient absorption data indicate that the energy-transfer rate between two isoenergetic Zn porphyrins in a linear trimeric array terminated by a Fb porphyrin is (52 ± 19 ps)-1 in toluene at room temperature, while the time-resolved fluorescence data suggest that it may be significantly faster. Accordingly, incorporation of multiple isoenergetic pigments in extended linear or two-dimensional arrays will permit efficient overall energy transfer. (4) Medium effects, including variations in solvent polarity, temperature, viscosity, and axial solvent ligation, only very weakly alter (≤2.5-fold) the energy-transfer rates. However, the Fb porphyrin fluorescence in the Zn−Fb dimers is quenched in the polar solvent dimethyl sulfoxide (but not in toluene, castor oil, or acetone), which is attributed to charge-transfer with the neighboring Zn porphyrin following energy transfer. Collectively, the studies demonstrate that extended multiporphyrin arrays can be designed in a rational manner with predictable photophysical features and efficient light-harvesting properties through use of the diarylethyne-linked porphyrin motif. DA - 1996/11/13/ PY - 1996/11/13/ DO - 10.1021/ja961612f VL - 118 IS - 45 SP - 11181-11193 SN - 0002-7863 ER - TY - JOUR TI - Soluble synthetic multiporphyrin arrays .1. Modular design and synthesis AU - Wagner, RW AU - Johnson, TE AU - Lindsey, JS T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY AB - A set of porphyrin building blocks has been developed for the construction of light-harvesting model compounds and related molecular photonic devices. The porphyrins are facially encumbered to enhance solubility in organic solvents, are employed in a defined metalation state (free base (Fb) or zinc chelate), and bear peripheral functional groups such as iodo or ethyne for joining the porphyrins via covalent bonds. The coupling of an iodophenylporphyrin and an ethynylphenylporphyrin via mild Pd-mediated reactions (2−4 mM of each porphyrin in toluene/triethylamine (5:1) with Pd2(dba)3 and AsPh3 at 35 °C for 2 h) yields the corresponding diphenylethyne-linked multiporphyrin array in 70−80% yield. The arrays are easily purified by a sequence of flash silica chromatography, preparative size exclusion chromatography, and gravity elution silica chromatography. The diphenylethyne linkers give a center-to-center separation of the porphyrins of ∼20 Å. Model light-harvesting compounds are easily prepared using Zn and Fb porphyrin building blocks. In order to investigate the role of the linker in through-bond electronic communication, and the effect of through-bond electronic communication on the rates and yields of photoinduced energy transfer in the arrays, four ZnFb dimers have been prepared that have a systematic increase in steric hindrance in the diphenylethyne unit. The presence of steric hindrance inhibits rotation of the phenyl group toward coplanarity with the porphyrin, thereby modulating the electronic communication. A linear ZnFbZn trimer and a right-angle ZnFbZn trimer have been prepared to probe the effects of geometry on electronic communication pathways. A linear ZnZnFb trimer has been synthesized to investigate the photodynamics of energy migration among isoenergetic zinc porphyrins. These multiporphyrin arrays have sufficient solubility (∼5 mM) for routine handling in organic solvents such as toluene, CH2Cl2, or CHCl3, and can be examined spectroscopically (1−10 μM) in diverse solvents such as tetrahydrofuran, acetone, dimethyl sulfoxide, and castor oil. This building block approach should make diverse multiporphyrin arrays readily available. DA - 1996/11/13/ PY - 1996/11/13/ DO - 10.1021/ja961611n VL - 118 IS - 45 SP - 11166-11180 SN - 0002-7863 ER - TY - JOUR TI - Boron-dipyrromethene dyes for incorporation in synthetic multi-pigment light-harvesting arrays AU - Wagner, RW AU - Lindsey, JS T2 - PURE AND APPLIED CHEMISTRY AB - Abstract DA - 1996/7// PY - 1996/7// DO - 10.1351/pac199668071373 VL - 68 IS - 7 SP - 1373-1380 SN - 0033-4545 ER -