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1999

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Articles 31 - 60 of 328

Full-Text Articles in Chemistry

Characterization And Electrochemical Behaviour Of Ce(Ⅲ) Amino Acid Imidazole Ternary Complexes, Hui-Xia Wu, Ze-Min Wang, Hai-Feng Yang, Zong-Rang Zhang Nov 1999

Characterization And Electrochemical Behaviour Of Ce(Ⅲ) Amino Acid Imidazole Ternary Complexes, Hui-Xia Wu, Ze-Min Wang, Hai-Feng Yang, Zong-Rang Zhang

Journal of Electrochemistry

Two Ce(Ⅲ)-amino acid-imidazole teranry complexe were synthesized,These complexes have the composition of Ce(Trp)3IM(NO3)3·3H2O and Ce(Phe)3IM(NO3)3 respectively. The IR spectra indicate that the carboxy group of amino-acid and the N atoms of imidazole are coordinated with Ce(Ⅲ) ion. Cyclic voltammetry was used to study the electrochemical behaviour of Ce(Ⅲ) ion, the mixture of Ce(Ⅲ) with ligands, and Ce(Ⅲ) binary or ternary complexes. Within the scan range of -0.1 to 1.10 V (vs.SCE), both of ternary complexes depicted completely irreversible electron transfer process.

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Subsidence, Mixing, And Denitrification Of Arctic Polar Vortex Air Measured During Polaris, M. Rex, R. J. Salawitch, G. C. Toon, B. Sen, J. J. Margitan, G. B. Osterman, J. F. Blavier, R. S. Gao, Stephen G. Donnelly Ph.D., E. Keim, J. Neuman, D. W. Fahey, C. R. Webster, D. C. Scott, R. L. Herman, R. D. May, E. J. Moyer, M. R. Gunson, F. W. Irion, A. Y. Chang, C. P. Rinsland, T. P. Bui Nov 1999

Subsidence, Mixing, And Denitrification Of Arctic Polar Vortex Air Measured During Polaris, M. Rex, R. J. Salawitch, G. C. Toon, B. Sen, J. J. Margitan, G. B. Osterman, J. F. Blavier, R. S. Gao, Stephen G. Donnelly Ph.D., E. Keim, J. Neuman, D. W. Fahey, C. R. Webster, D. C. Scott, R. L. Herman, R. D. May, E. J. Moyer, M. R. Gunson, F. W. Irion, A. Y. Chang, C. P. Rinsland, T. P. Bui

Chemistry Faculty Publications

We determine the degree of denitrification that occurred during the 1996-1997 Arctic winter using a technique that is based on balloon and aircraft borne measurements of NOy, N2O, and CH4. The NOy/N2O relation can undergo significant change due to isentropic mixing of subsided vortex air masses with extravortex air due to the high nonlinearity of the relation. These transport related reductions in NOy can be difficult to distinguish from the effects of denitrification caused by sedimentation of condensed HNO3. In this study, high-altitude balloon measurements are used to define the properties of air masses that later descend in the polar …

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Stereoselective Determination Oftrihexyphenidyl In Human Serum By Lc–Esi–Ms, Vladimı́R Čápka, Yan Xu, Yong Hong Chen Nov 1999

Stereoselective Determination Oftrihexyphenidyl In Human Serum By Lc–Esi–Ms, Vladimı́R Čápka, Yan Xu, Yong Hong Chen

Chemistry Faculty Publications

The antiparkinsonian drug trihexyphenidyl (THP) is currently manufactured and administered as a racemate. However, stereochemistry can play significant role in the drug’s pharmacokinetics, biotransformation, metabolism, interaction with cellular and tissue components and overall effect on human body. It is necessary to consider such a drug as a mixture of two compounds (drug enantiomers), with their own effect on the human body. The present paper describes a simple and sensitive LC–MS method for the stereoselective determination of THP in human serum. In this study, the sample was prepared by a solid-phase extraction (SPE) procedure. The enantiomer separation was done using native …

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First Example Of A Double Stranded Helicate With Square-Planar Coordination For The Metal, Marc Zimmer, Derek A. Tocher, Goutam K. Patra, Jnan P. Naskar, Dipankar Datta Nov 1999

First Example Of A Double Stranded Helicate With Square-Planar Coordination For The Metal, Marc Zimmer, Derek A. Tocher, Goutam K. Patra, Jnan P. Naskar, Dipankar Datta

Chemistry Faculty Publications

Reaction of dichlorobis(benzildihydrazone)Ni(II) with biacetylmonoxime in 1:4 molar proportion generates diamagnetic Ni2L2 where LH2 (H = dissociable oximato proton) is HO-N=C(CH3)-C(CH3)=N-N=C(C6H5)-C(C6H5)=N-N=C(CH3)-C(CH3)=N-OH. Our molecular mechanics calculations show that Ni2L2 is an unprecedented double stranded homotopic helicate with the metal ion having a square-planar N4 coordination.

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Cationic 5,10,15,20-Tetrakis(N-Methylpyridinium-4-Yl)Porphyrin Fully Intercalates At 5‘-Cg-3‘ Steps Of Duplex Dna In Solution, Anton B. Guliaev, Neocles B. Leontis Nov 1999

Cationic 5,10,15,20-Tetrakis(N-Methylpyridinium-4-Yl)Porphyrin Fully Intercalates At 5‘-Cg-3‘ Steps Of Duplex Dna In Solution, Anton B. Guliaev, Neocles B. Leontis

Chemistry Faculty Publications

The interaction of 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)p (T4MPyP4+ with the oligonucleotide DNA duplex [d(GCACGTGC)](2) was studied by two-dimensional 1H NMR spectroscopy, optical absorbance, circular dichroism, and molecular dynamics simulation employing particle mesh Ewald methods. T4MPyP4+ is one of the largest aromatic molecules for which intercalative binding to DNA has been proposed, although this has been called into question by recent X-ray crystallographic work [Lipscomb et al. (1996) Biochemistry 35, 2818-2823]. T4MPyP4+ binding to [d(GCACGTGC)]2 produced a single set of (mostly) upfield-shifted DNA resonances in slow exchange with the resonances of the free DNA. Intra- and intermolecular NOEs …

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Confined Water In Hydrophobic Nanopores: Dynamics Of Freezing Into Bilayer Ice, Jan Slovak, Kenichiro Koga, Hideki Tanaka, Xiao Cheng Zeng Nov 1999

Confined Water In Hydrophobic Nanopores: Dynamics Of Freezing Into Bilayer Ice, Jan Slovak, Kenichiro Koga, Hideki Tanaka, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Molecular dynamics simulations for a thin film of water confined to a slit nanopore are performed in order to investigate the dynamic process of crystallization of the system. The system upon freezing creates a bilayer ice crystal composed of two layers of hexagonal rings. We perform one simulation at T=257 K during which the system remains a supercooled liquid state, and another one at T=253 K during which the system freezes. Many patterns of molecular arrangement are found upon freezing, and an account is given of the origin of multiple peaks in the distributions of binding energy and …

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Imaging Point Defects In A Liquid Environment: A Model Afm Study, Kenichiro Koga, Xiao Cheng Zeng Nov 1999

Imaging Point Defects In A Liquid Environment: A Model Afm Study, Kenichiro Koga, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Effects of the liquid on atomic force microscopy (AFM) imaging are examined for a model system consisting of a hexagonal flake of seven Lennard-Jones (LJ) atoms as a multiatom tip, a monolayer of LJ crystal containing a single point defect as a substrate, and three-site model water as the liquid. A previous simulation [Koutsos et al., Europhys. Lett. 26, 103 (1994)] has shown that the true atomic resolution of a point defect cannot be achieved in vacuum by use of the multiatom tip. Here we examine the feasibility of such atomic resolution when both the tip and substrate are immersed …

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Stabilization Of Polystyrene By Friedel-Crafts Chemistry: Effect Of Position Of Alcohol And The Catalyst, Jin Zhu, Michael A. Mckinney, Charles Wilkie Nov 1999

Stabilization Of Polystyrene By Friedel-Crafts Chemistry: Effect Of Position Of Alcohol And The Catalyst, Jin Zhu, Michael A. Mckinney, Charles Wilkie

Chemistry Faculty Research and Publications

Polystyrene has been copolymerized with 4-vinylbenzyl alcohol, 4-(2-hydroxyethyl)styrene, and 4-(3-hydroxypropyl)styrene and it has been shown that thermal cross-linking of these copolymers is dependent upon the alcohol content. When the alcohol content is low, no thermal cross-linking is observed. When various phosphate esters are present as catalysts with these low alcohol content copolymers, cross-linking is observed at temperatures of about 250°C but not at lower temperatures. Cross-linking enhances the thermal stability of the copolymers. Studies of the thermal stability of the copolymers and their blends with the catalysts have been performed using thermogravimetric analysis and thermogravimetric analysis coupled to Fourier transform …

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Method Of Storing Active Zero Valent Zinc Metal, Reuben D. Rieke Oct 1999

Method Of Storing Active Zero Valent Zinc Metal, Reuben D. Rieke

Department of Chemistry: Faculty Publications

A novel Zerovalent Zinc species and an organozinc reagent are disclosed. The Zerovalent Zinc species is directly pro duced by reaction of a reducing agent on a Zinc Salt, preferably Zn(CN). The organozinc regent results from the reaction of the Zerovalent Zinc species and an organic compound having one or more stable anionic leaving groups. These organozinc reagents include a wide spectrum of functional groups in the organic radical, and are useful in a variety of reactions Schemes.

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Macrocyclic Antibiotics As Separation Agents, Daniel W. Armstrong Oct 1999

Macrocyclic Antibiotics As Separation Agents, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Macrocyclic antibiotics having ring structures with at least 10 members act as separation agents in crystallization, precipitation, filtration, electrophoresis and chromatography. The macrocyclic antibiotics include ansamacrolides, macrolides, macrocyclic peptides, polyenes and derivatives thereof. The process has been found to be especially advantageous for separation of optical isomers by electrophoresis and chromatography.

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Pretransitional Behavior Above The Nematic-Isotropic Phase Transition Of An Auxetic Trimer Liquid Crystal, Daeseung Kang, Milind P. Mahajan, Shiyong Zhang, Rolfe G. Petschek, Charles Rosenblatt, Chaobin He, Puwei Lu, A.C. Griffin Oct 1999

Pretransitional Behavior Above The Nematic-Isotropic Phase Transition Of An Auxetic Trimer Liquid Crystal, Daeseung Kang, Milind P. Mahajan, Shiyong Zhang, Rolfe G. Petschek, Charles Rosenblatt, Chaobin He, Puwei Lu, A.C. Griffin

Faculty Publications

Static Light scattering and electric field-induced Kerr measurements were performed above the nematic-isotropic phase transition of a terminal-lateral-lateral-terminal negative Poisson ratio trimer. Far both measurements the inverse susceptibility was observed to be nearly linear with temperature, a result inconsistent with our previously reported Kerr data [Phys. Rev. E 58, 2041 (1998)]. [S1063-651X(99)11010-9].

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Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani Oct 1999

Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani

Chemistry Faculty Research & Creative Works

Mechanical testing and surface fractography were used to characterize the fracture of E-glass fiber reinforced epoxy composites as a function of the silane coupling agent used. gamma-Aminopropyltriethoxysilane (APS) and delta-aminobutyltriethoxysilane (ABS) were used because these have been shown to have different interfacial mobilities at multilayer coverage. The values of the properties studied generally increased from untreated c, as determined from a Mode I translaminar fracture toughness tests, for the untreated composites (10.5 ± 0.4 kJ/m2) was lower than that for the ABS-treated composites (14.3 ± 2.1 kJ/m2) which was lower than that for the APS-treated composites (17.1 ± 2.4 kJ/m2). …

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Evaluation Of The Enantiomeric Composition Of Amino Acids In Tobacco, John P. Kullman, Xianghong Chen, Daniel W. Armstrong Oct 1999

Evaluation Of The Enantiomeric Composition Of Amino Acids In Tobacco, John P. Kullman, Xianghong Chen, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Despite the fact that several studies have reported the concentrations of various free amino acids in tobacco, their enantiomeric composition is unknown. Both the absolute and enantiomeric compositions of proline, alanine, asparagine, aspartic acid, valine, methionine, leucine, and phenylalanine were determined for three strains of tobacco leaf, three types of smokeless tobacco, and six different blended filtered and nonfiltered reference cigarettes. Some of the highest levels of D-amino acids ever found in agricultural products were observed. Possible mechanisms for the production of these D-amino acids are considered. The relevance of D-amino acids in tobacco is discussed.

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Validity Of The Independent-Particle Approximation In X-Ray Photoemission: The Exception, Not The Rule, D. Hansen, Oliver Hemmers, H. Wang, Dennis W. Lindle, P. Focke, I. A. Sellin, Clemens Heske, H. S. Chakraborty, P. C. Deshmukh, S. T. Manson Oct 1999

Validity Of The Independent-Particle Approximation In X-Ray Photoemission: The Exception, Not The Rule, D. Hansen, Oliver Hemmers, H. Wang, Dennis W. Lindle, P. Focke, I. A. Sellin, Clemens Heske, H. S. Chakraborty, P. C. Deshmukh, S. T. Manson

Environmental Studies Faculty Publications

A combined experimental and theoretical study of argon valence photoionization illustrates the discovery of the broad lack of validity of the independent-particle approximation (IPA) for x-ray photoemission. In addition to previously known breakdowns of the IPA, which are limited to high photon energies and regions very near threshold, the observed breakdown in photoionization at intermediate energies demonstrates generally that the IPA is valid only in very restricted domains. These restrictions are expected to be relevant throughout the periodic table, with consequences for a wide variety of applications.

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Enantioselective Synthesis Of Dual Serotonergic Azanoradamantane Sc-52491, Daniel Becker, Robert K. Husa, Alan E. Moormann, Clara I. Villamil Oct 1999

Enantioselective Synthesis Of Dual Serotonergic Azanoradamantane Sc-52491, Daniel Becker, Robert K. Husa, Alan E. Moormann, Clara I. Villamil

Chemistry: Faculty Publications and Other Works

A racemic synthesis of azanoradamantane (±)-3 was accomplished via Yamamoto's MAD-catalyzed Diels-Alder protocol. Subsequently, a scalable asymmetric synthesis of azanoradamantane benzamide SC-52491 was carried out employing Helmchen's asymmetric Diels-Alder methodology to construct all four contiguous asymmetric centers with the correct relative stereochemistry and in 99.3% e.e.

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An Xps Study Of The Radiation-Induced Effect On The Thermal Degradation And Charring Of Butadiene And Its Copolymers, Jianwei Hao, Shaoli Wu, Charles Wilkie, Jianqi Wang Oct 1999

An Xps Study Of The Radiation-Induced Effect On The Thermal Degradation And Charring Of Butadiene And Its Copolymers, Jianwei Hao, Shaoli Wu, Charles Wilkie, Jianqi Wang

Chemistry Faculty Research and Publications

A pseudo-in-situ XPS approach shows that cross-linking induced by irradiation may lead to char formation even though it shows only a small or no effect on the onset temperature of degradation.

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Humic Substances As Interferences In The Analysis Of Nitrite In Water, Stephanie Ann Tebault Oct 1999

Humic Substances As Interferences In The Analysis Of Nitrite In Water, Stephanie Ann Tebault

Chemistry & Biochemistry Theses & Dissertations

Humic substances are of current interest because of their roles in environmental processes involving pollutants. It is also becoming recognized that humic substances may interfere in analysis of environmental samples though the possible adverse effects do not appear to be fully appreciated. The present effort focuses on determining whether humic materials interfere in the analysis of nitrite in water using the Griess reaction. This is a well-known reaction using nitrosation to gjve a diazonium salt followed by coupling with an appropriate reagent to form a dye. This colorimetric method continues to be applied in the laboratory and the field for …

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Trace Gas Emissions From Laboratory Biomass Fires Measured By Open-Path Fourier Transform Infrared Spectroscopy: Fires In Grass And Surface Fuels, Jon G. Goode, Robert J. Yokelson, Ronald A. Susott, Darold E. Ward Sep 1999

Trace Gas Emissions From Laboratory Biomass Fires Measured By Open-Path Fourier Transform Infrared Spectroscopy: Fires In Grass And Surface Fuels, Jon G. Goode, Robert J. Yokelson, Ronald A. Susott, Darold E. Ward

Chemistry and Biochemistry Faculty Publications

The trace gas emissions from six biomass fires, including three grass fires, were measured using a Fourier transform infrared (FTIR) spectrometer coupled to an open-path, multipass cell (OP-FTIR). The quantified emissions consisted of carbon dioxide, nitric oxide, water vapor, carbon monoxide, methane, ammonia, ethylene, acetylene, isobutene, methanol, acetic acid, formic acid, formaldehyde, and hydroxyacetaldehyde. By including grass fires in this study we have now measured smoke composition from fires in each major vegetation class. The emission ratios of the oxygenated compounds, formaldehyde, methanol, and acetic acid, were 1–2% of CO in the grass fires, similar to our other laboratory and …

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Micromagnetics Simulation Of Nanoshaped Iron Elements: Comparison With Experiment, Ngocnga Dao, S. R. Homer, Scott L. Whittenburg Sep 1999

Micromagnetics Simulation Of Nanoshaped Iron Elements: Comparison With Experiment, Ngocnga Dao, S. R. Homer, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

A micromagnetics simulation has been conducted on nanostructured magnetic elements of iron in order to investigate the effect of the shape of the element on magnetic properties, such as domain formation and hysteresis loops. These results are compared with recent experimental studies. The results display an impressive agreement with both the experimentally observed magnetic domains in individual particles as well as the shape of the hysteresis loops. The simulation results then explain features in the hysteresis loops in terms of vortice formation and motion.

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Examination Of Ionic Liquids And Their Interaction With Molecules, When Used As Stationary Phases In Gas Chromatography, Daniel W. Armstrong, Lingfeng He, Yan Song Liu Sep 1999

Examination Of Ionic Liquids And Their Interaction With Molecules, When Used As Stationary Phases In Gas Chromatography, Daniel W. Armstrong, Lingfeng He, Yan Song Liu

Chemistry Faculty Research & Creative Works

Stable room-temperature ionic liquids (RTILs) have been used as novel reaction solvents. They can solubilize complex polar molecules such as cyclodextrins and glycopeptides. Their wetting ability and viscosity allow them to be coated onto fused silica capillaries. Thus, 1-butyl-3- methylimidazolium hexafluorophosphate and the analogous chloride salt can be used as stationary phases for gas chromatography (GC). Using inverse GC, one can examine the nature of these ionic liquids via their interactions with a variety of compounds. The Rohrschneider-McReynolds constants were determined for both ionic liquids and a popular commercial polysiloxane stationary phase. Ionic liquid stationary phases seem to have a …

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Contour Temperature Programmed Desorption For Monitoring Multiple Chemical Reaction Products, Charles C. Chusuei, J. V. De La Peña, John A. Schreifels Sep 1999

Contour Temperature Programmed Desorption For Monitoring Multiple Chemical Reaction Products, Charles C. Chusuei, J. V. De La Peña, John A. Schreifels

Chemistry Faculty Research & Creative Works

A simple method for obtaining a comprehensive overview of major compounds desorbing from the surface during temperature programmed desorption (TPD) experiments is outlined. Standard commercially available equipment is used to perform the experiment. The method is particularly valuable when high molecular mass compounds are being studied. The acquisition of contour temperature programmed desorption (CTPD) spectra, sampling 50-dalton mass ranges at a time in the thermal desorption experiments, is described and demonstrated for the interaction of benzotriazole adsorbed on a Ni(111) surface. Conventional two-dimensional TPD spectra can be extracted from the CTPD by taking vertical slices of the contour.

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Mössbauer Effect Study Of Filled Antimonide Skutterudites, Gary J. Long, Dimitri Hautot, Fernande Grandjean, Donald T. Morelli, Gregory P. Meisner Sep 1999

Mössbauer Effect Study Of Filled Antimonide Skutterudites, Gary J. Long, Dimitri Hautot, Fernande Grandjean, Donald T. Morelli, Gregory P. Meisner

Chemistry Faculty Research & Creative Works

The iron-57 Mössbauer spectra of a series of Ce-filled antimonide skutterudites, CexFe4-yCoySb12, where x varies from 0.22 to 0.98 and y varies from 0 to 3.5, have been measured at 295 K. In addition, the spectra of Ce0.60Fe2Co2Sb12 and Ce0.82Fe3CoSb12 have been measured from 85 to 295 K and the spectra of Ce0.35FeCo3Sb12 and Ce0.98Fe4Sb12 have been measured from 4.2 to 295 K. The spectra, all of which consist of …

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Thermal Decomposition Of Cross-Linked Polybutadiene And Its Copolymers, David D. Jiang, Galina F. Levchik, Sergei V. Levchik, Charles Wilkie Sep 1999

Thermal Decomposition Of Cross-Linked Polybutadiene And Its Copolymers, David D. Jiang, Galina F. Levchik, Sergei V. Levchik, Charles Wilkie

Chemistry Faculty Research and Publications

Polybutadiene and two copolymers containing butadiene and styrene have been cross-linked by thermal processes, by the use of initiators in solution, and by intimately mixing an initiator with the polymer and then heating this blend. The most efficient cross-linking process is the use of an intimate blend of the initiator and polymer. Most cross-linking processes lower the onset temperature of degradation, presumably because chain scission reactions occur simultaneously with cross-linking, while also increasing the fraction of non-volatile residue which is produced. It is believed that the density of cross-links is responsible for the increased yield of non-volatile residue.

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Comparative Molecular Field Analysis (Comfa) Of Phenyl Ring Substituted Methylphenidates, Milind Misra Aug 1999

Comparative Molecular Field Analysis (Comfa) Of Phenyl Ring Substituted Methylphenidates, Milind Misra

Theses

Comparative Molecular Field Analysis (CoMFA) was performed on 30 methylphenidate analogues having phenyl ring substituents at the 2-, 3-, and 4-positions in an attempt to explain the structure-activity relationships of the analogues. Several CoMFA studies were carried out using different conformations of methylphenidate as the template structures for the corresponding alignment rules. The identification of the bioactive conformation was variously based on the interfeature distances in WIN 35,428, on cluster analysis, and on a comparison of active methylphenidate analogues. The sensitivity of the models to various CoMFA parameters was compared. These parameters included altering the size and spacing of the …

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Structural And Electrochemical Studies On Lithium Manganese Oxide Containing Li+ Prepared By Hydrothermal Method For Lithium Ion Batteries, De-Yao Liu, Jin-Kua You, Wei Chu, Yong Yang, Zu-Geng Lin Aug 1999

Structural And Electrochemical Studies On Lithium Manganese Oxide Containing Li+ Prepared By Hydrothermal Method For Lithium Ion Batteries, De-Yao Liu, Jin-Kua You, Wei Chu, Yong Yang, Zu-Geng Lin

Journal of Electrochemistry

In this paper, Todorokite manganese oxides containing Li+ with large tunnel structure (sample M5) have been synthesized by hydrothermal methods from natural manganese oxide nano fiber (sample M4). The structure and composition of the samples were characterized and analyzed by XRD, ICP, TGA and DTA. Its electrochemical behavior as a cathode materials for rechargeable lithium ion insertion were studied by galvanostatic charge/discharge measurements. XRD results show that the sample M4 is mainly composed of Birnessite and Vernadite structure. Although the sample M4 shows a high initial capacity of approximately 150 mAh/g, its performances decrease gradually over 30 cycles. It …

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Preparation And Ionic Conductivity Of Nanometer-Sized Li2+XGdXSi1+XO3 By The Sol-Gel Method, Ru-Fen Chen, Xiu-Qin Song, Hua-Ting Liu Aug 1999

Preparation And Ionic Conductivity Of Nanometer-Sized Li2+XGdXSi1+XO3 By The Sol-Gel Method, Ru-Fen Chen, Xiu-Qin Song, Hua-Ting Liu

Journal of Electrochemistry

Li2+xGdxSi1-xO3(x =0～0.15) samples have been prepared by the Sol-Gel method. The power samples were characterized by DTA-TG, XRD and TEM. Ionic conductivity of the sinter was determined by means of A-C impedance measurements. The experimental results showed that the range of solid-solution was 0 < x ≤ 0.09, while the conductivity of samples raised with increasing amount of Gd2O3 added, and average grain size of samples was 80 nm. In comparing with the samples by the conventional solid state reaction, the samples prepared by Sol-Gel method required lower temperature and presented higher ionic conductivity.

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In Situ Ftirs Studies Of The Electrochemically Induced Coupling Of Osmium Nitrido Species In Acetonitrile, Sheng-Pei Chen, Shi-Gang Sun Aug 1999

In Situ Ftirs Studies Of The Electrochemically Induced Coupling Of Osmium Nitrido Species In Acetonitrile, Sheng-Pei Chen, Shi-Gang Sun

Journal of Electrochemistry

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Spectroellipsometric Studies On Electrochemistry And Its Application, Zong-Qing Huang, Sheng-Tao Zhang, Shang-Fen Xie, Chang-Guo Chen, Yu-Ru Yang, Wei Zhu Aug 1999

Spectroellipsometric Studies On Electrochemistry And Its Application, Zong-Qing Huang, Sheng-Tao Zhang, Shang-Fen Xie, Chang-Guo Chen, Yu-Ru Yang, Wei Zhu

Journal of Electrochemistry

Ellipsometric measurements are often extremely sensitive to the presence of very thin surface layers,to changes in their thickness (or coverage), and to changes in surface topography at an atomic scale. These characteristics make the use of ellipsometry for electrochemical studies particularly attractive. The ellipsometric studies on electrochemistry and its applications carried out in the Electrochemical Laboratory of Chongqing University are reviewed briefly: 1)The studies on electrochemistry of classical ellipsometry. 2)The new function Vop suggested by the authors. 3)The applications of new approcaches with new function Vop suggested by the authors.

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Deactivation Of Nickel Oxide/Hydroxide To Electrooxidation Of H2Po2 Anions On Nickel Electrodes In Alkaline Solutions, Tai-Xiang Jiang, Hui-Huang Wu Aug 1999

Deactivation Of Nickel Oxide/Hydroxide To Electrooxidation Of H2Po2 Anions On Nickel Electrodes In Alkaline Solutions, Tai-Xiang Jiang, Hui-Huang Wu

Journal of Electrochemistry

Electrooxidation of hypophosphite anions on polycrystalline nickel in alkaline solutions has been investigated by cyclic voltammetry and open circuit potential measurements. The results are explained based on the mechanism that the first step of hypophosphite oxidation is the adsorption of hypophosphite ions on nickel, followed by the homolysis of its hydrogen bond with the formation of radicals. The oxidation of hypophosphite on nickel in alkaline medium occurs at lower potentials between ca. -0.8 V— -1.1 V (SCE) and phosphite ion is the only oxidation product. There is no indication of hypophosphite oxidation at higher potentials. Severe deactivation of the surface …

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The Electrochemical Apparent Effective Thickness Of Alkanethiol Self-Assembled Monolayers, Xiao-Li Cui, Dian-Lu Jiang, Peng Diao, Jun-Xin Li, Ru-Ting Tong, Deng-Ping Gu, Xin-Kui Wang Aug 1999

The Electrochemical Apparent Effective Thickness Of Alkanethiol Self-Assembled Monolayers, Xiao-Li Cui, Dian-Lu Jiang, Peng Diao, Jun-Xin Li, Ru-Ting Tong, Deng-Ping Gu, Xin-Kui Wang

Journal of Electrochemistry

The electrochemical behavior of octadecanethiol self-assembled monolayers modified gold electrode in different concentration of Fe(CN)63-/4- is investigated by cyclic voltammetry and electrochemical impedance spectroscopy. It is determined that the apparent he-terogeneous rate constant ks is in the order of 10-6 cm·s-1, the apparent electron transfer coefficients are 0.15 and 0.22. The apparent effective thickness of the SAMs is established which can be used to describe the molecular ordering degree of self-assembled monolayers.

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