Physical Sciences and Mathematics Commons^™

Determination Of Cystine By Second Order Differential Simple Oscillographic Voltammetry, Fu-Fang Tao, Jian-Bin Zheng

Journal of Electrochemistry

In 0.2 mol/L NaOH, cystine can cause an sensitive incision at -0.5 V (vs.SCE) of cathodic branch of dE/dt_E curve or second order differential simple oscillogram. Based on the oscillographic charateristic, second order differential simple oscillographic voltammetry was applied to the determination of cystine in tablet. The linear range and the detection limit for determination of cystine were 2.5×10-6～3.5×10-5 mol/L and 1.0×10-6 mol/L, respectively. The relative standard deviation for 2.000×10-5 mol/L cystine was 1.8% (n=5).

Preparation And Characterization Of Y-Type Carbon Nanotubes By Using Anodized Alumina Oxide (Aao) Template, Jing Zhang, Quan-Yong Gao, Yong Yang

Journal of Electrochemistry

In this work, potential_modulation method was used in two_step anodization process to make an AAO template with Y_type nanochannels. Then Y_type carbon nanotubes with controlled length and branch angle were prepared in the template based on chemical vapor decomposion (CVD) method with Co particles as catalyst and C2H2 as carbon source. The Y_type nanotube branches exhibit the angle distribution ranging from 20° to 120°. The results demonstrated that the oxidation potential should be responsible for the angles and length of the branches. Short pulse and high oxidation potential will result in the short and dense nanotube branches.

Application Of Hydrogen-Storage Alloy Electrode In Electrochemical Reduction Of Glucose, Hui Chen, You-Gen Tang, Zheng Tang

Journal of Electrochemistry

Electrolysis of glucose was performed at constant potential using hydrogen_storage alloy as catalytic reduction electrode. It was found that the superficial treatment and activation of hydrogen_storage alloy powder had obvious effects on improving the current efficiency of sorbitol. Under the optimums, current efficiency of sorbitol by electrolyzing glucose was over 94%. The yield of sorbitol was over 80%, the lifespan of electrode was tested and analyzed, the ways of regeneration were discussed.

Preparation And Properties Of The Composite Microporous Pvdf-Hfp/Sio_2 Based Polymer Electrolytes, Bao-Wen Zhang, Lu Qi, Hui Hen, Xiao-Hui Zhu, Li-Yan Liu, Yun-Xiang Ci

Journal of Electrochemistry

Microporous PVDF_HFP/SiO2 film were prepared using a solvent/nonsolvent method_phase inversion method and the volatile plasticizers DMC, DEC or PC. The conductivity of the films increased pore volume measured by a nonsolvent uptake method. The conductivity of 1.86×10-3 Sm-1 were obtained using the liquid electrolyte LiPF6(1 M) in EC/DMC (1:1).

The Current Fluctuations Of Carbon Steel In Nano_2-Nacl Solutions, Yu-Ming Tang, Yu Zuo

Journal of Electrochemistry

The characteristics of current fluctuations of A3 carbon steel in NaNO2_NaCl solutions were studied with potentiostatic and potentiodynamic polarization methods. The steel remained stable passivation in 0.1 mol/L NaNO2 solution without Cl-. After NaCl was added in to the solution, current fluctuations with a characteristic of quick increase and slow decrease occurred, indicating quick dissolution and slow re_passivation of the metastable pits. The metastable pitting may cause accumulated corrosion damage around certain area and result in observable pits. With the increase of chloride concentration, the occurring potential for metastable pits Em rised, and peak values and frequency of current fluctuations …

Support For The Nye County Early Warning Drilling Program, Irene Farnham, Klaus J. Stetzenbach, Amy J. Smiecinski

Publications (YM)

This final report details the activities completed for Task 8 of the University and Community College System of Nevada (UCCSN) Cooperative Agreement with the US Department of Energy (DOE). Task 8, titled "Support for the Nye County Early Warning Drilling Program" provided for a variety of hydrochemical analyses. The requirements of the University and Community College System of Nevada (UCCSN) Quality Assurance (QA) Program were followed for all work performed on this task. The primary activity performed by the Harry Reid Center for Environmental Studies (HRC) for Task 8 was to provide hydrochemical analyses of the groundwater samples collected from …

Dendrimer-Encapsulated Nanoparticle Precursors To Supported Platinum Catalysts, Huifang Lang, R Alan May, Brianna L. Iversen, Bert D. Chandler

Chemistry Faculty Research

In this contribution, we report the successful preparation of supported metal catalysts using dendrimer-encapsulated Pt nanoparticles as metal precursors. Polyamidoamine (PAMAM) dendrimers were first used to template and stabilize Pt nanoparticles prepared in solution. These dendrimer-encapsulated nanoparticles were then deposited onto a commercial high surface area silica support and thermally activated to remove the organic dendrimer. The resulting materials are active oxidation and hydrogenation catalysts. The effects of catalyst preparation and activation on activity for toluene hydrogenation and CO oxidation catalysis are discussed.

The Electronic Structure Of Metal/Alkane Thiol Self-Assembled Monolayers/Metal Junctions For Magnetoelectronics Applications, Y.A. Ovchenkov, H. Geisler, J.M. Burst, S.N. Thornburg, C.A. Ventrice Jr., Chunjuan Zhang, Jody G. Redepenning, Yaroslav B. Losovyj, Luis G. Rosa, Peter A. Dowben, Bernard Doudin

Jody Redepenning Publications

Long-chain alkane thiols use in metal to organic self-assembled monolayer to metal junctions may be limited by orientational disorder, and photoemission studies suggest that several molecular layers may be needed for the dielectric layer to be effective. Several alkane thiols were investigated in a range of junctions areas 10–10² μm². Top layer contact deposition, activated with Pd clusters resulted in a high yield of junctions that were not electrically shorted and are stable over a wide temperature range. Zerobias anomalies, observed at low temperatures, are attributed to a Coulomb blockade associated with the Pd clusters.

Method Of Solubilizing Single-Walled Carbon Nanotubes In Organic Solutions, Robert C. Haddon, Jian Chen

Chemistry Faculty Patents

Naked single-walled nanotube carbon metals and semiconductors are dissolved in various organic solutions.

Aerobic Denitrification Of Pseudomonas Aeruginosa Monitored By Online Nad(P)H Fluorescence, Fan Chen, Qing Xia, Lu-Kwang Ju

Chemical, Biomolecular, and Corrosion Engineering Faculty Research

Continuous cultures of Pseudomonas aeruginosa (ATCC 9027) maintained at different dissolved oxygen concentrations (DO) were studied for the effects of DO on various culture properties, especially aerobic respiration and denitrification. The DO was varied from 0 mg/liter (completely anoxic conditions) to 1.3 mg/liter and measured with optical sensors that could accurately determine very low DO based on oxygen-quenched luminescence. The strain was found to perform aerobic denitrification; while the specific rate decreased with increasing DO, denitrification persisted at approximately 1/8 of the maximum rate (1.7 mmol/g of cells/h) even at relatively high DO (1 to 1.3 mg/liter). In the presence …

Acid-Base Properties Of Aluminum In A Hardwood Forest Soil (Or: Acid Rain Is Dead…), Chris E. Johnson

Chris E Johnson

No abstract provided.

Acid-Base Properties Of Aluminum In A Hardwood Forest Soil (Or: Acid Rain Is Dead…), Chris E. Johnson

Civil and Environmental Engineering

No abstract provided.

Habitat Use Of Sympatrically Nesting Fish Crows And American Crows, Brook Lauro, John Tanacredi Ph.D.

Faculty Works: CERCOM

We examined habitat use of sympatric Fish Crows (Corvus ossifragus) and American Crows (C. brachyrhynchos) nesting in the vicinity of waterbird breeding locations at the Rockaway Peninsula, New York City. Fish Crows nested significantly more often at natural habitats, including coastal dunes and salt marsh islands; American Crows nested significantly more often at residential and recreational areas. In regard to potential foraging areas, Fish Crows nested closer to waterbird colonies and to the water's edge while American Crows nested closer to a garbage source and to lawns. Fish Crows nested significantly more often in deciduous trees …

Effect Of External Electric Field On The Bulk And Interfacial Properties Of Weakly Dipolar Fluid In Slab-Shaped And Sphere-Shaped Systems, V.B. Warshavsky, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The effect of a uniform electric field on the bulk and interfacial properties of a model dipolar fluid is investigated by using a modified mean-field density functional theory. Particular attention is given to the dependence of the vapor-liquid phase coexistence in a slab-shaped system on the direction of the electric field with respect to the slab surfaces, as well as in the sphere-shaped system on the surrounding dielectric permittivity. For planar vapor-liquid interfaces, the interfacial profiles of the orientation order parameters and components of the dielectric-permittivity tensor are calculated. Analytical expressions for these interfacial profiles and their dependence on the …

Silica Based Solid Phase Extraction Sorbent With A Removable Alkyltrimethylammonium Surfactant Phase, Tony Oakes

Masters Theses & Specialist Projects

Presented is a solid phase extraction (SPE) sorbent having a removable "stationary phase." This removable phase that consists of alkyltrimethylammonium surfactant is initially immobilized onto hydrophilic strong cation exchange resin. The surfactant chain through hydrophobic interactions extracts hydrophobic analytes in the same manner as conventional bonded alkyl moieties on silica based non-polar sorbents. For the extraction of very hydrophobic species with conventional sorbents, solvents used for analyte elution are generally toxic and not directly instrument compatible. The chosen solvent must be strong enough to efficiently break hydrophobic interactions between the analyte and sorbent. Using a removable "stationary phase," hydrophobic interactions …

Melanoma And Seborrheic Keratosis Differentiation Using Texture Features, Srinivas V. Deshabhoina, Scott E. Umbaugh, William V. Stoecker, Randy Hays Moss, Subhashini K. Srinivasan

Chemistry Faculty Research & Creative Works

Purpose: To explore texture features in two-dimensional images to differentiate seborrheic keratosis from melanoma.

Methods: A systematic approach to consistent classification of skin tumors is described. Texture features, based on the second-order histogram, were used to identify the features or a combination of features that could consistently differentiate a malignant skin tumor (melanoma) from a benign one (seborrheic keratosis). Two hundred and seventy-one skin tumor images were separated into training and test sets for accuracy and consistency. Automatic induction was applied to generate classification rules. Data analysis and modeling tools were used to gain further insight into the feature space. …

Study Of The Electronic Properties Of Some Ytterbium Filled Skutterudites By Magnetic Susceptibility And X-Ray Absorption And Tin-119 Mössbauer Spectroscopy, Fernande Grandjean, Gary J. Long, Bernard M. Mahieu, Ji Hui Yang, Gregory P. Meisner, Donald T. Morelli

Chemistry Faculty Research & Creative Works

Magnetic susceptibility, ytterbium L_III-edge x-ray absorption and tin-119 Mössbauer spectral measurements have been carried out to probe the electronic structure of ytterbium and tin in the filled or partially filled skutterudite compounds, Yb_yCo₄Sb_12-xSn_x, over a range of x and y values. The ytterbium valence obtained from the magnetic susceptibility and ytterbium L_III-edge x-ray absorption measurements is in excellent agreement and clearly reveals an evolution from intermediate valence ytterbium for x=0 to nearly divalent ytterbium for x=0.8. This evolution parallels an increase in the unit cell volume and hence …

Distance-Dependent Electron Hopping Conductivity And Nanoscale Lithography Of Chemically-Linked Gold Monolayer Protected Cluster Films, Francis P. Zamborini, Laura E. Smart, Michael C. Leopold, Royce W. Murray

Chemistry Faculty Publications

Films of monolayer protected Au clusters (MPCs) with mixed alkanethiolate and ω-carboxylate alkanethiolate monolayers, linked together by carboxylate–Cu2+–carboxylate bridges, exhibit average edge-to-edge cluster spacings that vary with the numbers of methylene segments in the alkanethiolate ligand as determined by a combined atomic force microscopy (AFM)/UV-Vis spectroscopy method. The electronic conductivity (σEL) of dry films is exponentially dependent on the cluster spacing, consistent with electron tunneling through the alkanethiolate chains and non-bonded contacts between those chains on individual, adjacent MPCs. The calculated electronic coupling factor (β) for tunneling between MPCs is 1.2 Å−1, which is similar to …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Quarterly Progress Report (June 1 – August 31, 2003), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

As indicated in the original proposal, the primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate target materials for applications in spallationneutron- target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including Alloy HT-9, Alloy EP 823 and Type 422 stainless steel. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these materials are being evaluated in aqueous environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. …

Evaluation Of Adsorption Effects On Measurements Of Ammonia, Acetic Acid, And Methanol, Robert J. Yokelson, Ted J. Christian, Isaac T. Bertschi, Wei M. Hao

Chemistry and Biochemistry Faculty Publications

[1] We examined how adsorption and desorption of gases from inlets and a cell could affect the accuracy of closed-cell FTIR measurements of carbon dioxide (CO₂), carbon monoxide (CO), methane (CH₄), nitric oxide (NO), nitrogen dioxide (NO₂), methanol (CH₃OH), acetic acid (CH₃COOH), and ammonia (NH₃). When standards were delivered to the cell through a stainless steel inlet, temporarily reduced transmission was observed for CH₃OH and NH₃. However, a halocarbon wax coated inlet (normally used on the system) had excellent transmission (comparable to room temperature …

Immobilization Of Fission Iodine By Reaction With A Fullerene Containing Carbon Compound And Insoluble Natural Organic Matrix, Spencer M. Steinberg, David W. Emerson, Gary Cerefice

Separations Campaign (TRP)

The recovery of iodine released during the processing of used nuclear fuel poses a significant challenge to the transmutation of radioactive iodine. During the first year of this program we have examined the potential of Fullerene Containing Carbon compounds (FCC) developed by KRI, and natural organic matter (NOM) as sorbents for iodine released during the reprocessing of nuclear fuel. This work involved the development of bench-scale testing of the FCC and NOM material in a simulated process off-gas environment.

During the first two quarters of this program we explored various analytical methods available for measurement of iodine, iodide, and iodate. …

Rust, Glue, And Molecules -- Understanding The Role Of Molecular Structure On Macroscopic Interfacial Properties, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

Pyridoxamine Traps Intermediates In Lipid Peroxidation Reactions In Vivo: Evidence On The Role Of Lipids In Chemical Modification Of Protein And Development Of Diabetic Complications, Thomas O. Metz, Nathan L. Alderson, Mark E. Chachich, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Maillard or browning reactions between reducing sugars and protein lead to formation of advanced glycation end products (AGEs) and are thought to contribute to the pathogenesis of diabetic complications. AGE inhibitors such as aminoguanidine and pyridoxamine (PM) inhibit both the formation of AGEs and development of complications in animal models of diabetes. PM also inhibits the chemical modification of protein by advanced lipoxidation end products (ALEs) during lipid peroxidation reactions in vitro. We show here that several PM adducts, formed in incubations of PM with linoleate and arachidonate in vitro, are also excreted in the urine of PM-treated animals. The …

Redox Scale For Assigning An Oxidizing/Reducing Potential To Groundwater: Method Development And Initial Results, Julie Bertoia, Vernon Hodge, Klaus J. Stetzenbach, Amy J. Smiecinski

Publications (YM)

This report outlines the progress on Task 33 of the Department of Energy's Yucca Mountain Cooperative Agreement with the University and Community College System of Nevada (UCCSN). The task is titled "The Experimental Determination of a "Redox Scale" for Assigning an Oxidizing/Reducing Potential to Groundwater from Wells in the Nye County Early Warning Drilling Program: A Scale for Predicting the Solubility and Mobility of Elements Commonly Found in Nuclear Wastes". The purpose of the research was to determine the concentrations of the various electrochemical oxidation states or redox species of eleven elements in groundwater samples collected from the Nye County …

Hygroscopic Growth Of Ammonium Sulfate/Dicarboxylic Acids, Matthew E. Wise, Jason D. Surratt, Daniel B. Curtis, John E. Shilling, Margaret A. Tolbert

CUP Faculty Research

Recent studies have shown that tropospheric sulfate aerosols commonly contain 50% by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. We have measured the water activity of pure dicarboxylic acids and eutonic mixtures of ammonium sulfate/dicarboxylic acids at 25°C and have calculated van't Hoff factors for each individual system. We have also used the vapor pressure data to determine the hygroscopic growth curves for pure dicarboxylic acids and eutonic mixtures and provide power law fits to the data. For the systems studied we find that the presence …

Electrochemical Preparation Of Chitosan/Hydroxyapatite Composite Coatings On Titanium Substrates, Jody G. Redepenning, Guhanand Venkataraman, Jun Chen, Nathan Stafford

Jody Redepenning Publications

Composite coatings containing brushite (CaHPO₄ • 2H₂O) and chitosan were prepared by electrochemical deposition. The brushite/chitosan composites were converted to hydroxyapatite/chitosan composites in aqueous solutions of sodium hydroxide. The coatings ranged from 1 to 15% chitosan by weight. Qualitative assessment of the coatings showed adhesion signifi cantly improved over that observed for electrodeposited coatings of pure HA.

Magnetic Storage Device Using Induced Magnetic Reversal Of A Cobalt Element Array, Hanning Chen, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

The effects of the applied field, cell size, and cutting area on the ‘‘seed’’ induced magnetic reversal of a cobalt element array have been studied by a stochastic dynamic micromagnetics code using the Laudau–Lifshitz–Gilbert equation. Three magnetic reversal mechanisms under different magnitudes of the applied field have been investigated by examining the energy profiles. To minimize the effect of the thermal fluctuations on the switching time, an applied field with magnitude around 0.7 or 0.8 T and an element array with cutting area less than 10 nm X 10 nm are required. By using the smaller cellsize, the switching time …

Coarse-Graining Description Of Solid Systems At Nonzero Temperature, Z.-B. Wu, Dennis J. Diestler, Ruqiang Feng, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The quasicontinuum (QC) technique, in which the atomic lattice of a solid is coarse-grained by overlaying it with a finite-element mesh, has been employed previously to treat the quasistatic evolution of defects in materials at zero temperature. It is extended here to nonzero temperature. A coarse-grained Hamiltonian is derived for the nodes of the mesh, which behave as quasiparticles whose interactions are mediated by the underlying (non-nodal) atoms constrained to move in unison with the nodes. Coarse-grained thermophysical properties are computed by means of the Monte Carlo (MC) method. This dynamically constrained QC MC procedure is applied to a simple …

Density Matrix View Of The Double Well Problem, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

Hall And Wolynes Reply [Reply To Comment On ‘‘Microscopic Theory Of Network Glasses’’], Randall W. Hall, Peter G. Wolynes

Randall W. Hall