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Kinetic Behavior Of The Pt/Ysz Solid Electrolyte Interface Exposed To O2+He Mixture, Yi Jiang, Wenzhao Li, Lixin Cao, Jingwang Yan

Journal of Electrochemistry

Electrochemical behavior of the Pt/YSZ solid electrolyre interface has been investigated by cyclic voltammetry and linear potential sweep technique. It was found that the electrochemical adsorption of oxygen on the Pt surface follows the Temkin adsorption model. The amount of oxygen species increases logarithmically with time. Two oxygen species are electrochemically formed on the Pt surface. One is atomically adsorbed, the other probably subsurface oxygen or Pt oxide. The electrochemical reduction of adsorbed oxygen is kinetically irreverable. The cathodic peak potential is affected both by the potential sean rate and the amount of oxygen ahorbed on the surface. Kinetic parameters, …

Applicadons Of Laser In Electrochemistry (Ⅰ), Bin Ren, Zhongqun Tian

Journal of Electrochemistry

This paper is the first part of a comprehensive review of laser applied in electrochemistry. At first, it briefly introduces the advantages, history and exporimental setup of laser electrochamistry. Then it reviews laser applications in electrochemical deposition, polymerization, etching, polishing, corrosion, adsorption/desorption and reactions as well as photoelectrochemical switching and storage.

Determination Of Transport Number Of The Modified Liclo4-(Peo)20 Polymer Electrolyte, Ruqi Zhou, Qngguo Liu, Weihua Qiu, Yun Zhang, Yuee Zhao, Leiling Yang

Journal of Electrochemistry

In this work a combination method of A.C. Impedance and chronoamperometry was used to determine the lithium ion transport number of LiClO₄·(PEO)₂₀·(PC)₁₂·(EC)₁₂ polymer electrolyte. It is known that lithium is thermodynamically unstable in non-aqueous or polymer electrolytes, leading to the formtion of a film on lithium surface, called as solid electrolyte interphase (SEI). The presence of SEI layer will greatly influence the experimental result of lithium ion transport number. The new method avoid the effect of SEI layer, and can give correct transport number of lithium ion in the electrolyte of DCIO_{4 …}

Preparation Techique Of Foamed Nickel By Electrodeposition, Xihua He, Ronghui Hu, Hanxi Yang, Zhengzhong Zuo

Journal of Electrochemistry

This paper describes the preparation technique and operation conditions for manufacturing foamed nickel by chemilcal pretreament, electrodeposition and heat treatment. The foamed nickel made in this method showed high porosity, uniformity and considerable strength and tenacity,applicable for various secondary battery electrodes.

The Electrochemical Behavior Of C60-Chemically Modified Poly(N-Vinylcarhzole)In 1 Mol/L Liclo4-Thf Solutions, Yu Chen, Zuen Huang, Ruifang Cai, Fupin Zhang

Journal of Electrochemistry

The electrochemical behavior of C₆₀-PNVC copolymer in 1 mol/L LiClO₄-THF solutions has been studied by cyclic voltammetry. The results demonstrated that there are considerable differences of electronic structure between PNVC (Poly (N-vinylcarbazole)) and C₆₀-PNVC copolymer, this being consistent with the ESR results and the oxidstion-reduction activarion of pure PNVC by C₆₀-chemical modification. In the potential region, 1.3V～-3.5V, five steps, 0. 90V/0.60V, 0.20V/0.00V, -1.05V/-1.30 V, -1.25V/-1.75 V, -2.00V/-2.50V, of oxidation/reduction proceases were indicated in the cyclic voltammetry for pure PNVC, whereas seven steps, 0.20V/0.20V, -0.30V/-0.50 V, -0. 60V/-0.60 V, -0.80V/-1.10 V, -1.95V/-2.10 V, …

Study On The Manufacture Of Pt/C Gas-Diffusion Electrodes, Yonglin Ma

Journal of Electrochemistry

The various methods of manufacturing gas-diffusion electrodes are reviewed and a new method of preparing the Pt/C electrocatalyst and the gas-diffusion electrodes is explored in this paper. The electrochemical performance of resulting electrodes in concentrated phosphoric acid for oxygen reduction at 150℃ are compared with the commercial electrode which purched from Giner Inc. (U. S. A). The results show that the performance of the Pt/C electrodes which manufactured by the method in this paper has been greatly improved. Therefor, a fuel cell using such electrodes has high industrial value.

Gas–Liquid Nucleation In Two-Dimensional Fluids, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A nonclassical theory of nucleation, based on the density-functional (DF) approach, is developed for the gas–liquid transitions of two-dimensional (2D) Lennard-Jones (LJ) fluids. The methods of Weeks–Chandler–Andersen perturbation theory are used to approximate the LJ potential with a temperature-dependent hard-disk diameter plus an attractive tail. The resulting free energy functional is then used to calculate the free energy barrier to nucleation. We find that the curvature of the 2D nucleus is not important to the rate of nucleation (in contrast to the 3D counterpart). The effect of curvature is readily inferred from the ratio of nucleation rate from classical Becker–Dö̈ring …

Heme Proton Resonance Assignments And Kinetics Study In High-Spin And Mixed-Spin Metmyoglobin Complexes By Chemical Exchange Nmr Spectroscopy, Ying Luo

Dissertations and Theses

NMR studies of paramagnetic hemoproteins have improved significantly our understanding of the structure-function relationship of hemoproteins in general. Up to date most of the studies focus on low-spin ferric systems which are characterized by relatively narrow resonance peaks and concomitant better resolution.

However, characterizing in detail the NMR spectra of high-spin ferric hemoproteins is important since there are several hemoproteins, such as peroxidases, catalases, oxygenases, and some ferricytochromes that contain high-spin iron (III) in their biologically active forms. Yet assigning resonances from heme peripheral protons and/or heme pocket residues in high-spin myoglobins is a daunting undertaking. Only a sparse number …

Photoinduced Electron Transfer Along A Β-Sheet Mimic, Alexei B. Gretchikhine, Michael Y. Ogawa

Chemistry Faculty Publications

Electron energy-loss spectroscopy (EELS) is used to determine the energies of low-lying singlet and triplet states of the title compound. The EELS measurements give a splitting of 0.45 eV between the two lowest π f π* singlet states, as confirmed by optical absorption measurements, but do not give a discernable splitting between the corresponding triplet states. The experimental results are interpreted with the aid of ab initio electronic structure calculations using the CIS and CASPT2 methods. The calculations are consistent with the experiments, giving a much larger splitting between the π f π* singlet as compared to the π f …

Construction Of Accurate Molecular Models Using Laser Stereolithography And Determination Of Nmr Spectra For Amiloride Hydrochloride And Its Free Base, Ana Deborah Ofsievich

Theses

Accurate molecular models were constructed by a rapid prototyping process, called stereolithography. This process uses a computer-controlled laser to cure and solidify a photosensitive liquid polymer. Using a computer-aided design (CAD) program, spheres of appropriate van der Waals or CPK radii were drawn and placed in the three dimensional CAD space, in accordance with the atomic coordinates obtained from quantum mechanical calculations and from neutron diffraction data. These design data were used to drive the stereolithography system where the models were built in the same shape as the CAD image. The models built for the purpose of this work consisted …

Continuous Monitoring Of Volatile Organic Compound Emissions Using Microtrap Based Injection Technique And Gas Chromatography, Wenjun Chen

Theses

A microtrap is made by packing a small diameter tubing with an adsorbent. The microtrap can be rapidly heated with a pulse of electrical current resulting in a sharp desorption that can act as an injection for GC separation. The microtrap can be used in several configurations to concentrate and inject sample in continuous, on-line monitoring system.

In this research a laboratory scale catalytic incinerator was set up and volatile organic compounds in the incinerator effluents were monitored using the microtrap based injection systems. The detection systems used were gas chromatography and nonmethane organic carbon (NMOC) analyzer. Conventional sample valve, …

Examination Of The Origin, Variation, And Proper Use Of Expressions For The Estimation Of Association Constants By Capillary Electrophoresis, Kimber L. Rundlett, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Over the last several decades a variety of techniques have been developed to determine apparent equilibrium constants for molecular association in solution (e.g., to micelles, proteins, cyclodextrins, antibiotics, etc.). The relationships describing binding isotherms appear in several forms and have been given several different names. It is well known that most of these expressions are closely related and that some may be more advantageous than others for experimental or statistical reasons. In the case of electrophoresis, association constants are calculated from the relationship between ligand concentration and the measured electrophoretic mobility of the solute. This relationship has appeared in many …

Termolecular Proton Transfer Reactions Assisted By Ionic Hydrogen Bond Formation: Reactions Of Aromatic Cations With Polar Molecules, George M. Daly, Michael Mautner, Y. B. Pithawalla, M. Samy El-Shall

Chemistry Publications

We present a new method that applies resonant‐two‐photon ionization to generate reactant ions selectively in the source of a high‐pressure mass spectrometer (R2PI‐HPMS) for kinetic and equilibrium studies. Applications to reactions that would be obscured otherwise in a complex system are illustrated in mixtures of benzene with polar solvent molecules (S). We observe a novel type of proton transferreactions from C₆H₆ ^+• to two S molecules where S=CH₃CN, CH₃OH, C₂H₅OH and CH₃COOC₂H₅, and from C₆H₅CH₃ ^+• to two …

Substitution Reactions Of (C5ph5)Cr(Co)3: Structural, Electrochemical, And Spectroscopic Characterization Of (C5ph5)Cr(Co)2l, L = Pme3, Pme2ph, P(Ome)3, D. John Hammack, Mills M. Dillard, Michael Castellani, Arnold L. Rheingold, Anne L. Rieger, Philip H. Rieger

Chemistry Faculty Research

The radical complex (C₅Ph₅)Cr(CO)₃ reacts with small, neutral, monodentate Lewis bases (PMe₃, PMe₂Ph, P(OMe)₃) in THF at −78 °C (PMe₂Ph reacts at ambient temperature) to yield the monomeric substitution products (C₅Ph₅)Cr(CO)₂L·THF as thermally stable solids. Electrochemical and spectroscopic data are provided. An X-ray crystal structure of the hemisolvate (C₅Ph₅)Cr(CO)₂PMe₃·0.5THF was obtained. Frozen-solution ESR spectra of (C₅Ph₅)Cr(CO)₂L in toluene are comparable to those of other low-spin d^{5 …}

The Lipooligosaccharides Of Haemophilus Ducreyi Are Highly Sialylated, William Melaugh, A A. Campagnari, B W. Gibson

Chemistry Faculty Publications

The major lipooligosaccharides of the sexually transmitted pathogen Haemophilus ducreyi 35000 have been previously found to terminate in N-acetyllactosamine and sialyl-N-acetyllactosamine, Neu5Ac alpha 2-->3Gal beta 1-->4GlcNAc (W. Melaugh, N. J. Phillips, A. A. Campagnari, M. V. Tullius, and B. W. Gibson, Biochemistry 33: 13070-13078, 1994). In this study, mass spectrometry and composition analyses have shown that the lipooligosaccharides from three other H. ducreyi strains also contain N-acetyllactosamine and are highly sialylated (approximately 30 to 50%), although one African strain was found to contain neither of these structural features.

Effects Of Radial Thermal Gradients In Hplc, Jennifer Splan

Honors Theses, 1963-2015

Due to the widespread use of chromatography, improving efficiency in chromatography is continually an area of interest. Researchers have suggested that the method of column temperature control influences efficiency. To insure reproducible retention times, HPLC columns are often thermostated with a water jacket. Under such conditions, however, a radial thermal gradient may arise from the heat produced by friction between the stationary and mobile phases. If the core of the column is allowed to warm up while the walls are kept at a constant temperature, the solute in the core of the column will elute faster than will that at …

The Determination Of The Concentration Of Common Inorganic Anions Using Capillary Zone Electrophoresis: An Analytical Chemistry Laboratory Experiment, Michael A. Janusa

Faculty Presentations

No abstract provided.

Effects Of Analyte Ph On The Accuracy Of Capillary Zone Electrophoresis As A Quantitative Analytical Technique, Michael A. Janusa

Faculty Presentations

No abstract provided.

Designing A Better Matrix For Solidification/Stabilization Of Hazardous Waste With The Aid Of Bagasse (Lignin) As A Polymer Additive To Cement, Michael A. Janusa

Faculty Presentations

No abstract provided.

Space-Based Genetic Cryoconservation Of Endangered Species, Michael Noah Mautner

Chemistry Publications

Genetic materials of endangered species must be maintained, for cryoconservation, permanently near liquid nitrogen temperatures below 77 K. Due to the instability of human institutions, permanent safety is best provided at storage sites that maintain passively the needed low temperatures, and provide barriers to access. The required conditions are available in permanently shaded polar lunar craters with equilibrium temperatures of 8 to 40 K, on the moons of Saturn, and unshielded storage satellites. A genetic depository can be incorporated readily into planned lunar programmes.

A Monte Carlo Study Of Methanol Clusters (Ch3oh)N, N=5-256, D. Wright, M. S. El-Shall

Chemistry Publications

The thermodynamic and structural properties of methanol clusters (CH₃OH) _N , N=5–15, 20, 30, 60, 128, 256 and the bulk liquid have been investigated using Monte Carlo simulation. Calculated properties as a function of size include electrostatic and dispersive contributions to the configurational energy, configurational heat capacities,fractal dimension, density profiles, order parameters characterizing dipole and bond vector orientation, and the Lindemann index. The clusterheat capacities as a function of N possess an interior maximum near N=128 and converge to the bulk value from above. Monocyclic, semiplanar structures are found to persist at liquidlike temperatures up to …

Condensation Of Supersaturated Vapors Of Hydrogen Bonding Molecules: Ethylene Glycol, Propylene Glycol, Trimethylene Glycol, And Glycerol, David B. Kane, M. Samy El-Shall

Chemistry Publications

The critical supersaturations required for the homogeneous nucleation (rate of 1 drop cm⁻³ s⁻¹) of ethylene glycol, propylene glycol, trimethylene glycol and glycerol vapors have been measured over wide temperature ranges (e.g., 280–400 K) using an upward thermal diffusion cloud chamber. At lower temperatures the experimental nucleation rates are much higher than the predictions of the classical nucleation theory. Glycerol shows the best agreement between experiment and theory in the temperature range of 340–370 K. An apparent increase in the critical supersaturation of glycerol is observed with increasing carrier gas (helium) pressure and this effect is more …

An Improved Synthesis Of 2-(Hydroxymethyl)Indene, Hasan Palandoken, William T. Mcmillen, Michael H. Nantz

Chemistry and Biochemistry

No abstract provided.

[(Co)H(Pph3)2-Arachno-Osb3h8], Nigam Rath, J. Bould, L. Barton

Chemistry & Biochemistry Faculty Works

A single-crystal X-ray diffraction study of the species 2-carbonyl2-hydrido-trans-2,2-bis(triphenylphosphine)-2-osma-arachno-tetraborane confirms the structure as a tetraborane(10) butterfly with a trans-[(CO)H(PPh3)2Os] group replacing a BH2 group at a wing-tip or 2-position. It is compared with the previously reported ruthenaborane analogue (CO)H(PPh3)2-arachno-RuB3H8.

Oxidation States And Magnetism Of Fe Nanoparticles Prepared By A Laser Evaporation Technique, B. J. Jönsson, T. Turkki, V. Ström, M. S. El-Shall, K. V. Rao

Chemistry Publications

Nanoparticles of iron and iron oxide have been prepared in a thermal diffusion cloud chamber using pulsed laser evaporation. SEM/TEM studies of these particles reveal a size distribution with a mean diameter of about 60 Å. This is consistent with the mean particle size estimated from the magnetic data. The oxidation levels of these nanoparticles prepared at different partial oxygen pressures were investigated using FTIR. All the samples are found to exhibit superparamagnetism with blocking temperatures ranging from 50 K to above room temperature. Magnetic anisotropy constants are calculated from the frequency dependence of the blocking temperatures are found to …

An Nmr Investigation Of The Effect Of Hydrogen Bonding On The Rates Of Rotation About The C-N Bonds In Urea And Thiourea, Karl A. Haushalter, Janice Lau, John D. Roberts

All HMC Faculty Publications and Research

The interaction between urea and tetrabutylammonium acetate was investigated in dimethylformamide/ dimethyl sulfoxide solutions using ¹H and 15^N NMR. The chemical-shift behavior of the urea protons is consistent with a urea-acetate hydrogen-bonded complex involving both carboxylate oxygens and the urea hydrogens trans to the carbonyl oxygen with K_assoc = 120 ± 10. Line shape analysis of the temperature-dependent ¹H NMR spectra show that ∆G^‡ for rotation about the C-N bond of urea changes only slightly from 11.0 ± 0.1 to 11.2 ± 0.1 kcal/mol on 1:1 molar addition of tetrabutylammonium acetate to a dilute solution of urea. A parallel investigation …

Highly Reactive Form Of Copper And Reagents Thereof, Reuben D. Rieke

Department of Chemistry: Faculty Publications

A novel Zerovalent copper species and an organocopper reagent are disclosed. The Zerovalent copper species is directly produced by reaction of a reducing agent with a combination of copper(I) cyanide or halide and an alkali metal halide salt. The organocopper reagent resulting from the reaction of the zerovalent copper species and an organic compound having one or more stable anionic leaving groups is a stable reagent that will not significantly homocouple and under controlled conditions tolerates the presence of nitrile, epoxide, imine, enone, ketone, ester, allyl and benzyl groups within the organo radical. The reagent can be controlled so that …

The Temperature Dependence Of Ultra Violet Sulfur Dioxide Absorption Cross Sections, Alexis Brunner

Honors Theses, 1963-2015

Atmospheric sulfur dioxide data became available in 1982 during and after the eruption of El Chichon, when the Total Ozone Mapping Spectrometer, TOMS, received increased absorption in the shortest wavelength channels of the instrument. TOMS was designed to map the daily global total ozone field. The increased absorption was later determined to be due to sulfur dioxide because it is a gaseous volcanic substituent that has corresponding absorption to that seen in the TOMS data. Currently there is no way to develop an algorithm that will accurately subtract the effects of sulfur dioxide from the TOMS data in order to …

Conformational Changes In Diphtheria Toxin Fragment B Upon Inserting Into Lipid Bilayers Stuided By Fluorescence Resonant Energy, Patricia L. Barker

Whittier Scholars Program

In this project Diphtheria toxin (DT) was purified and digested into subunits: fragment A (DTA) and fragment B (DTB). DTB was isolated from the solution to investigate its conformational changes upon interaction with phospholipid bilayers using model membrane liposomes and fluorescence spectroscopy. Resonant energy transfer occurs between the DTB and the dye. The dye fluorescence blue shifts in the presence of the liposomes. Decreased fluorescence is observed when the conjugate interacts with the vesicles, and the transfer efficiency increases. Conformational changes are triggered by contact of DTB with the membrane in an acidic environment.

The Investigation Of Aluminum Sulfate-Potassium Chloride Solid Phase Reaction, İ. Ayhan Şengi̇l

Turkish Journal of Chemistry

It was found that aluminum sulfate reacts with potassium chloride to produce K_{2}SO_{4}, Al_{2}O_{3}, and Cl_{2} in the solid phase at 700 ^{\circ}C. This reaction was investigated with thermal analysis under air and nitrogen atmosphere. By changing temperature and time parameters, the actual yield of conversion in question was examined analytically and the optimum temperature and time were found for the reaction. The rate expression of the solid phase reaction was also investigated and the rate equation was obtained.