Chemistry Commons^™

Studies On The Failure Modes Of Stationary Vrla Batteries, Yibo Tong, Xiangming Qiu

Journal of Electrochemistry

In order to improve the reliability and the quality of stationary valve-regulated lead-acid (VRLA) batteries, the failure modes of the stationary VRLA batteries which caused by the water loss and the thermal runaway are studied. The water loss may be solved by increasing the Oxygen-recombination efficiency, choosing the suitable grid material and the additives of megative paste, decreasing the corrosion of the positive plates. The thermal runaway may be solved by decreasing the inner ohmic resistance of VRLA batteries, improving the outside condition of batteries such as putting into the absorbing-heat material between the abtteries etc..

Study Of〔Co(2. 5 Nm) Pt(2. 5 Nm)〕N (N≥50) Multilayer By Electrocrystallization, Renhe Yin, Weiming Cao, Yanpin Guo, Huifen Ji

Journal of Electrochemistry

The electrocrystallization of Co(2.5 nm)/Pt(2.5 nm)_n (n ≥50) multilayer has been carried out under potential control, based on observation of reflection electron microscopy (REM). Monatomic steps on Pt single crystal surfaces have been imaged using a conventional transmission electron microscope in the reflection made. The REM images have revealed three dimintional growth of Co electrocrystallization at high polarization of -1.15 V (vs.Hg/Hg₂SO₄). The structure of the specimen was examined by small or high angle X-ray diffration technique. The modulation period of a multilayered structure is 5.0 nm.

Preparation Of Pbo2/Ti Plate Electrode, Zhigang Shao, Baolian Yi, Xinge Zhang, Enjun Zhang

Journal of Electrochemistry

The perchlorate was made up of a lead dioxide plate elcetrode and an oxygen cathode. By measuring the flow capacity of cell gas in the cell, and by means of CV, SEM, XRD, the performances of the lead dioxide plate electrodes are evaluated. The influence of changes in the concentrations of electroplating solutions (F, HNO₃, Bi³⁺, Ni²⁺, Fe³⁺ and surface active agent) is investigated. The results show that the concentrations of Fe³⁺ in the solutions must be lower 0.01 g/L, and the concentrations of HNO₃ in the solutions are about 20 …

Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Battery Ⅲ. Improvement Of Artificially Imposed Solid Electrolyte Film On Cell Performance, Shuhua Ma, Xiabin Jing, Fosong Wang

Journal of Electrochemistry

The improving effect of solid electrolyte film artificially imposed on carbon electrode was investigated. The result showed that both the charge/discharge capacity and first charge/discharge efficiency, to a certain extent, were enhanced, and the result also suggested the effectiveness of the substitution of the artificially imposed solid electrolyte film for the inherent passivating film which was formed on the surface of the carbon electrode while inserted in the electrolyte during charging or discharging. The Scanning Electron Microscope result displayed the compact and well-defined morphology of the artificially imposed crystalline film.

A Fluid In Contact With A Semipermeable Surface: Second-Order Integral Equation Approach, Douglas Henderson, Pawel Bryk, Stefan Sokolowski

Faculty Publications

An integral equation approach for a binary hard-sphere mixture interacting with a planar semipermeable wall (membrane) is formulated by using the second-order nonuniform or pair Ornstein–Zernike equation as well as the usual singlet Ornstein–Zernike equation. The results of the pair theory are compared with those obtained from the singlet theory and with computer simulation data. The pair approach is more accurate than the singlet theory.

Emissions From Smoldering Combustion Of Biomass Measured By Open-Path Fourier Transform Infrared Spectroscopy, Robert J. Yokelson, Ronald A. Susott, Darold E. Ward, James J. Reardon, David W. T. Griffith

Chemistry and Biochemistry Faculty Publications

Biomass samples from a diverse range of ecosystems were burned in the Intermountain Fire Sciences Laboratory open combustion facility. Midinfrared spectra of the nascent emissions were acquired at several heights above the fires with a Fourier transform infrared spectrometer (FTIR) coupled to an open multipass cell. In this report, the results from smoldering combustion during 24 fires are presented including production of carbon dioxide, carbon monoxide, methane, ethene, ethyne, propene, formaldehyde, 2-hydroxyethanal, methanol, phenol, acetic acid, formic acid, ammonia, hydrogen cyanide, and carbonyl sulfide. These were the dominant products observed, and many have significant influence on atmospheric chemistry at the …

Age-Dependent Increase In Ortho-Tyrosine And Methionine Sulfoxide In Human Skin Collagen Is Not Accelerated In Diabetes: Evidence Against A Generalized Increase In Oxidative Stress In Diabetes, Mary C. Wells-Knecht, Timothy J. Lyons, David R. Mccance, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

The glycoxidation products Nepsilon-(carboxymethyl)lysine and pentosidine increase in skin collagen with age and at an accelerated rate in diabetes. Their age-adjusted concentrations in skin collagen are correlated with the severity of diabetic complications. To determine the relative roles of increased glycation and/or oxidation in the accelerated formation of glycoxidation products in diabetes, we measured levels of amino acid oxidation products, distinct from glycoxidative modifications of amino acids, as independent indicators of oxidative stress and damage to collagen in aging and diabetes. We show that ortho-tyrosine and methionine sulfoxide are formed in concert with Nepsilon-(carboxymethyl)lysine and pentosidine during glycoxidation of collagen …

Predicting Electron Affinities With Density Functional Theory: Some Positive Results For Negative Ions, Gregory S. Tschumper, Henry F. Schaefer

Chemistry Faculty Research & Creative Works

The atomic electron affinities of the eight first row (H,Li,...,F) atoms as well as the adiabatic electron affinities of 12 first row diatomic and 15 first row triatomic molecules were determined using six different densities functional or hybrid Hartree-Fock/density functional methods. The 35 species were selected for having relatively well-established experimental electron affinities. Harmonic zero-point vibrational energy corrected electron affinities are also reported for the diatomic and triatomic molecules. Equilibrium geometries and harmonic vibrational frequencies are given for the 27 molecules and their anions as determined with each density functional method. Discussion focuses on comparison of theoretical and experimental electron …

Scanning Motions Of An Atomic Force Microscope Tip In Water, Kenichiro Koga, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Integral equation techniques are used to study scanning motions of a single-atom tip of the atomic force microscope (AFM) over a rigid, hydrophobic monolayer substrate in water. The calculated force curve is found to be oscillatory, in agreement with recent AFM experiments, which can lead to multiple scanning trajectories for the tip under a constant load. The unique trajectory along which the system is thermodynamically stable is revealed. This study shows that the tip may take a hopping motion over a defect-free substrate due to layering of water molecules between the tip and substrate.

39th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Preliminary program and registration information for the 39th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 3-7, 1997.

A Study Of The Volatile Matter Of Coal As A Function Of The Heating Rate, Enrique Santos

Masters Theses & Specialist Projects

A study of volatile matter yields as a function of the heating rate was conducted. A suite of 21 coal and coke samples varying in rank from anthracitic to lignitic and heating rates from 10°C/min to about 450°C/min were used in the study. Heating rates up to 60°C per minute, which are typically used in ASTM Test Method 5142 (instrumental Proximate Analysis), were achieved in a macro thermogravimetric analysis (TGA) system. Heating rates of 50-200°C/min were obtained in a micro TGA system. All measurements were made in a nitrogen atmosphere. The results of the study illustrate the dependance of the …

Extraction Of Premafloxacin Radiolabeled With Carbon Fourteen From Loam Soil, Steven Gregory Staskiewicz

Masters Theses

Premafloxacin is a fluoroquinolone antibiotic being developed by Pharmacia & Upjohn for veterinary indications. Since the parent drug and possibly metabolites will be applied to soil through the deposition of animal excreta, many regulatory agencies will require environmental assessment testing. In order to determine if ¹⁴C-premafloxacin would biodegrade in the soil, loam soil was extracted with solvents and C18 solid phase columns were used to isolate the compound after three weeks of incubation. In addition to extracting the soil, production of ¹⁴CO₂ was monitored by trapping the degradation by-product in 2 N NaOH. Liquid scintillation counting of …

Breakdown Of The Iron Passive Layer By Use Of The Scanning Electrochemical Microscope, David O. Wipf, John W. Still

Publications

The scanning electrochemical microscope (SECM) is used to generate localized corrosion at passivating iron surfaces by using the tip to generate Cl^– ions. Use of the SECM allows the rapid establishment of a locally aggressive chemical environment at a pre-selected site on the iron surface. The susceptibility for passive-layer breakdown and corrosion initiation was examined as a function of the time between the start of the passive-layer growth and the formation of Cl^- ions. The breakdown of the passive-layer was found to depend strongly on the passivation potential and the site of Cl^- formation on the iron …

Toward A Molecular Theory Of Vapor-Phase Nucleation. V. Self-Consistency In The Decoupled Dimer Limit, K.J. Oh, Xiao Cheng Zeng, H. Reiss

Xiao Cheng Zeng Publications

The previous papers of this series introduced a molecular i / υ cluster theory of vapor phase nucleation. This theory differs from most conventional ones in that the cluster (due to fluctuation) is not only characterized by its number of particles i but also by a spherical volume υ. Thus the free energy of formation of the cluster is not merely a one-dimensional function of the number of particles i but a two-dimensional function of both i and v (i.e., it is a free energy surface). In the first stage of this development (Refs. 1–3) the theory is based on …

Nondipole Resonant X-Ray-Raman Spectroscopy: Polarized Inelastic Scattering At The K Edge Of Cl2, J. D. Mills, J. A. Sheehy, T. A. Ferrett, S. H. Southworth, R. Mayer, Dennis W. Lindle, P. W. Langhoff

Chemistry and Biochemistry Faculty Research

Experimental and theoretical studies are reported on the inelastic (Raman) scattering of wavelength-selected polarized x rays from the K edge of gas-phase chlorine molecules. The polarized emission spectra exhibit prominent nondipole features consequent of phase variations of the incident and emitted radiation over molecular dimensions, as predicted by the Kramers-Heisenberg scattering formalism. Issues pursuant to the detection of core-hole localization by resonant Raman scattering from homonuclear diatomic molecules are critically examined. [S0031-9007(97)03486-8]

Evaluation Of Solid Phase Extraction Followed By Supercritical Fluid Elution Of Semi-Volatile Organic Compounds In Toxicity Characteristic Leachates, William Edward Corl Iii

Chemistry & Biochemistry Theses & Dissertations

The Environmental Protection Agency (EPA) developed the toxicity characteristic leaching procedure (TCLP) to determine the potential for unknown wastes to leach haz.ardous constituents into the environment. Methods currently being used for the extraction of semi-volatile organic compounds from aqueous TCLP leachates involve acid/base partitioning into methylene chloride. The concentrated extract is then analyzed by gas chromatography/mass spectrometry (GC/MS). The methods are either timeconsuming or labor intensive and they generate significant volumes of haz.ardous wastes themselves. Considering the haz.ards and disposal costs of methylene chloride wastes, great interest has been elicited by the EPA in other extraction techniques which would reduce …

Fabrication And Evaluation Of Boron-Doped Cvd Diamond Microelectrodes, Song Pang

Chemistry & Biochemistry Theses & Dissertations

The electrochemical behavior of boron-doped diamond microelectrodes has been studied in acetonitrile solutions containing two redox couples using cyclic voltammetry. One test system is 1-2.5 mM ferrocene, containing 0.1 M Tetrabutyl ammonium hexafluorophosphate (TBAH). This well-known reversible redox system involves only one electron transfer with little or no change in the solvation sphere and no breakage/formation of chemical bonds. Another test system is a 1 mM S₂Mo₁₈0₆₄^4- solution containing 0.1 M HCIO₄. This is one of the most complicated redox systems. In the presence of acid, electrons are usually transferred consecutively and …

Speciation Of Selenium In Serum, Alice Tsapayi-Musapatike

Chemistry & Biochemistry Theses & Dissertations

We investigated the separation of selenoprotein P and extracellular (serum) glutathione peroxidase using a concanavalin A affinity column. We were able to show that the method does not adequately separate serum glutathione peroxidase from selenoprotein P because human glutathione peroxidase binds strongly to the column. We also found that albumin can interfere with measurement serum of glutathione peroxidase activity when hydrogen peroxide is used as the substrate. When t-butyl hydroperoxide was used as the substrate, less than 10% of the measured activity was due to the presence of albumin. We also found that the pH of the elution buffer plays …

Comparison Of The Dichlorination Of Organic N-Chloramines By Caroate And By Bisulfite: A Kinetic Study, Said H. Lubbad

Chemistry & Biochemistry Theses & Dissertations

Bisulfite is commonly used to dechlorinate chlorinated municipal wastewater. However, several studies suggest that bisulfite is not effective in dechlorinating N-chlorinated amino components of wastewater. The purpose of this study was to investigate the effectiveness of an alternate dechlorinating agent, caroate (peroxysulfate), and to compare its rate of dechlorination of three different types of chloramines with that of bisulfite.

Four N-chlorinated amino compounds were investigated: N-chlorodiethylamine, N­ chloroalanylphenylalanine, N-chloroglycylphenylalanine, and N-[2-(N'-chloroimino)­ propanoyl]phenylalanine. These compounds were selected from different families of N­ chloramines to study the effect of structure on dechlorination by both caroate and bisulfite. At pH …

Solvent-Induced Interactions Between Hydrophobic And Hydrophilic Polyatomic Sheets In Water And Hypothetical Nonpolar Water, Kenichiro Koga, Xiao Cheng Zeng, Hideki Tanaka

Xiao Cheng Zeng Publications

Hydrophobic and hydrophilic interactions are two major intermolecular forces between hydrophobic nonpolar and hydrophilic polar sites of macromolecules or materials surfaces in solvents. To further understand these two interactions at the microscopic level, an idealized polyatomic model is devised, which includes hydrophobic, hydrophilic, and partially hydrophilic polyatomic planar square molecular sheets. The hydrophobic molecular sheet is composed of the Lennard-Jones particles while the hydrophilic molecular sheet consists of positive and negative charge sites. In the framework of the extended reference interaction site model integral equation theory the solvent-induced interactions (or the potential of mean forces) between two parallel molecular sheets …

A High Level Theoretical Investigation Of The Cyclic Hydrogen Fluoride Trimer, Gregory S. Tschumper, Yukio Yamaguchi, Henry F. Schaefer

Chemistry Faculty Research & Creative Works

A high-level ab initio theoretical investigation of the cyclic hydrogen fluoride trimer was carried out. The structures of the hydrogen fluoride monomer, dimer, and trimer were fully optimized at the coupled-cluster level of theory including single, double, and perturbatively applied connected triple excitations [CCSD(T)] using three large basis sets. Geometrical parameters, dipole moments, harmonic vibrational frequencies, infrared intensities, and total energies are reported for each equilibrium structure. Changes in bond lengths and shifts in HF stretching frequencies relative to the monomer, as well as the dissociation energies corresponding to various fragmentation pathways, are given for the dimer, trimer, and their …

Preparation Of Organometallic Complexed Sugars:  Hetero Diels−Alder Reactivity Of Tricarbonyl(Formyltrimethylenemethane)- Iron, Paul J. Kleindl, William A. Donaldson

Chemistry Faculty Research and Publications

No abstract provided.

Breakdown Of The Independent Particle Approximation In High-Energy Photoionization, E. W. B. Dias, H. S. Chakraborty, P. C. Deshmukh, S. T. Manson, Oliver Hemmers, P. Glans, D. Hansen, H. Wang, S. B. Whitfield, Dennis W. Lindle, R. Wehlitz, Jon C. Levin, I. A. Sellin

Environmental Studies Faculty Publications

The independent particle approximation is shown to break down for the photoionization of both inner and outer nℓ (ℓ>0) electrons of all atoms, at high enough energy, owing to interchannel interactions with the nearby ns photoionization channels. The effect is illustrated for Ne 2p in the 1 keV photon energy range through a comparison of theory and experiment. The implications for x-ray photoelectron spectroscopy of molecules and condensed matter are discussed.

Estimation Of Groundwater Velocities From Yucca Flat To The Amargosa Desert Using Geochemistry And Environmental Isotopes, Ronald L. Hershey, Steve Y. Acheampong

Publications (WR)

Geochemical modeling techniques were applied to groundwater flowpaths from Yucca Flat on the Nevada Test Site (NTS) to the Amargosa Desert, south of the NTS to estimate groundwater flow velocities for independent comparison to velocities calculated by other methods. The groundwater flowpaths examined considered flow in the carbonate aquifer beneath Yucca and Frenchman flats mixing with flow from carbonate aquifers east and southeast of the NTS and discharging at wells south of the NTS border. The approach used the computer codes WATEQ4F and NETPATH to calculate chemical speciation, determine the saturation state of mineral phases, and simulate mixing and the …

Numerical Modeling Of Self-Propagating Polymerization Fronts: The Role Of Kinetics On Front Stability, Stanislav E. Solovyov, Victor M. Ilyashenko, John A. Pojman

Faculty Publications

Frontal propagation of a highly exothermic polymerization reaction in a liquid is studied with the goal of developing a mathematical model of the process. As a model case we consider monomers such as methacrylic acid and n-butyl acrylate with peroxide initiators, although the model is not limited to these reactants and can be applied to any system with the similar basic polymerization mechanism. A three-step reaction mechanism, including initiation, propagation and termination steps, as well as a more simple one-step mechanism, were considered. For the one-step mechanism the loss of stability of propagating front was observed as a sequence …

Synthesis Of Biologically Active Substituted Chalcones, Kiel Steven Hoff

Masters Theses

Two different synthetic routes to poly-hydroxylated chalcones are investigated. The wittig synthesis and protection of the hydroxyl functionalities by forming the methyl ether followed by the base catalyzed Claissen-schmidt reaction and then deprotection were investigated. It was demonstrated that the protection-condensation- deprotection route was more efficient. The antiviral activity of 2,2', 4' - trihydroxychalcone against the HIV virus is also presented.

The Electrochemical Oxidation Of Organic Selenides And Selenoxides, Michael D. Ryan, Jiyi Yau, Michael Hack

Chemistry Faculty Research and Publications

The electrochemical oxidation of alkyl and aryl selenides was investigated in acetonitrile. The oxidation of diphenyl selenide and di(4‐methylphenyl) selenide led primarily to the formation of their respective selenoxides, which were identified by exhaustive coulometric oxidation and and analysis of the products. The selenoxide itself was not observed in the cyclic voltammetry of the selenide for two reasons: first, the protonation of the selenoxide by the acid formed from the reaction of water with the cation radical and second, the formation of a selenoxide hydrate. The formation of the hydrate with diphenyl selenoxide was verified by isolation of the dimethoxy …

Syntheses And Characterizations Of Unsymmetrical Porphyrins As Photosensitizers For A Solid-State Solar Cell, Yinping Zhao

Dissertations and Theses

Solar light is the most important source of regenerative energy and represents mankind's only inexhaustible energy source. One of today's most promising tools to make use of solar energy is its direct conversion into electrical energy in a photovoltaic cell. The practical use of these solar cells depends on the price of the devices and therefore of the obtained energy. The conventional silicon cells, although efficient, are expensive for common consumer applications. The Grätzel cell is a photovoltaic system for harvesting the sun's energy that operates at about 10-15% overall efficiency, like a conventional solar cell, but does it at …

Effects Of Tunneling Electrons And Local Field On Nanometer Region Solid / Liquid Interfacial Reactions ——Potential Controlled Stm Induced Nanoscale Modification Of H Terminated Si(111) Surfaces, Zhaoxiong Xie, Xiongwei Cai, Caihui Shi, Bingwei Mao, Zhaowu Tian

Journal of Electrochemistry

H-terminated n-Si(111) surface was found to be etched in 0.5% HF solution in nanometer scale while scanning the STM tip when the substrate potential was somehow lower than the open circuit potential at tunneling condition of V_b=+1.0 V (tip positive), I_t=1 nA. Much more stable Si surface was achievable at potentials much more negative than the open circuit potential (such as 500 mV negative to OCP) under the same tunneling condition. Furthermore, the etching rete at less negative potential was found to be somehow related to the tunneling current. These results indicate that the STM induced …

Studies Of Electrocatalytic Properties Of Electrode Of Dispersed Pt On Gc Support In Ethylene Glycol Oxidation, Shengpei Chen, Shigang Sun, Zhiyou Zhou, Shuanjing Hong

Journal of Electrochemistry

The structures and properties of electrocatalyst of dispersed Plutinum (Pt) on glassy carbon (GC) support under different conditions were studied using cyclic voltammetry, potential step technique, X-ray diffraction (XRD) and scanning Electron microscopy (SEM). The results indicated that after having been treated in high temperature,the dispersed Pt on GC support was recrystallised with preferented orientation, and the grain of Pt microcrystal become large and regular. It was illustrated that the dispersed Pt on GC support after high temperature treatment exhibited better stability and high activity for ethylene glycol oxidation.