Physical Sciences and Mathematics Commons^™

Afci Quarterly Input – Unlv April Through June, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Quarterly Report For The Trp Project, March–June 2003, Samir Moujaes, Yitung Chen, Kanthi Kiran Daiska, Chao Wu

Transmutation Sciences Materials (TRP)

The MTL is assumed to be a 5m long rectangular loop with a circular cross-section. Because of the non-symmetry, and due to the active participation of the secondary flows due to the elbows present in the rectangular loop model, the geometry is considered as a 3D model.

When the regions of maximum corrosion and precipitation are compared, they fall in the same zone for both the analytical and simulated models. The reason for a larger concentration flux in the case of turbulent flow than for the laminar flow can be explained by the concept of higher lateral diffusion in the …

Immobilization Of Fission Iodine By Reaction With A Fullerene Containing Carbon Compound And Insoluble Natural Organic Matrix: Quarterly Report April-June 2003, Spencer M. Steinberg

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. This proposal will develop and examine the use of Fullerene Containing Carbon (FCC) compounds as potential sorbents for iodine release from the reprocessing of nuclear fuel. This work will also include the development of bench-scale testing capabilities at UNLV to allow the testing of the FCC material in a simulated process off-gas environment. This experimental capability will also be used to test other potential sorption materials and processes, such as natural organic matter (NOM) and other promising alternatives. …

The Role Of The Dielectric Barrier In Narrow Biological Channels: A Novel Composite Approach To Modeling Single-Channel Currents, Artem B. Mamonov, Rob D. Coalson, Abraham Nitzan, Maria G. Kurnikova

Chemistry Faculty Research and Publications

A composite continuum theory for calculating ion current through a protein channel of known structure is proposed, which incorporates information about the channel dynamics. The approach is utilized to predict current through the Gramicidin A ion channel, a narrow pore in which the applicability of conventional continuum theories is questionable. The proposed approach utilizes a modified version of Poisson-Nernst-Planck (PNP) theory, termed Potential-of-Mean-Force-Poisson-Nernst-Planck theory (PMFPNP), to compute ion currents. As in standard PNP, ion permeation is modeled as a continuum drift-diffusion process in a self-consistent electrostatic potential. In PMFPNP, however, information about the dynamic relaxation of the protein and the …

Tools For The Automatic Identification And Classification Of Rna Base Pairs, Neocles B. Leontis, Huanwang Yang, Fabrice Jossinet, Li Chen, John Westbrook, Helen Berman, Eric Westhof

Chemistry Faculty Publications

Three programs have been developed to aid in the classification and visualization of RNA structure. BPViewer provides a web interface for displaying three-dimensional (3D) coordinates of individual base pairs or base pair collections. A web server, RNAview, automatically identifies and classifies the types of base pairs that are formed in nucleic acid structures by various combinations of the three edges, Watson-Crick, Hoogsteen and the Sugar edge. RNAView produces two-dimensional (2D) diagrams of secondary and tertiary structure in either Postscript, VRML or RNAML formats. The application RNAMLview can be used to rearrange various parts of the RNAView 2D diagram to generate …

Non-Watson-Crick Basepairing And Hydration In Rna Motifs: Molecular Dynamics Of 5s Rrna Loop E, Neocles B. Leontis, Kamila Réblová, Nad'a Špačková, Richard Štefl, Kristina Csaszar, Jaroslav Koča, J Sponer

Chemistry Faculty Publications

Explicit solvent and counterion molecular dynamics simulations have been carried out for a total of > 80 ns on the bacterial and spinach chloroplast 5S rRNA Loop E motifs. The Loop E sequences form unique duplex architectures composed of seven consecutive non-Watson-Crick basepairs. The starting structure of spinach chloroplast Loop E was modeled using isostericity principles, and the simulations refined the geometries of the three non-Watson-Crick basepairs that differ from the consensus bacterial sequence. The deep groove of Loop E motifs provides unique sites for cation binding. Binding of Mg2+ rigidifies Loop E and stabilizes its major groove at an intermediate …

A 59-Cobalt Nmr Investigation Of The Hydrogen/Deuterium Exchange Kinetics In Cobalt(Iii) Complexes, Michelle Mccombs

Masters Theses & Specialist Projects

Currently, the hydrogen/deuterium exchange kinetics in cobalt(III) complexes are being investigated. In the presence of deuterated solvents, (e.g. D2 0 and CH3CH20D) the amine hydrogens in the complexes are exchanged for deuteriums. For the hexaamminecobalt(III) ion, 19 isotopmers (H18D0 to HOD 18) are possible. For the tris(ethylenediammine)cobalt(III) ion, 13 isotopmers (HI 2D0 to HOD 12) are possible. Each hydrogen/deuteruim exchange causes a shift in the observed 59Co resonance of approximately 6 ppm. The rate constant of the hydrogen-deuterium exchange for the first H-D exchange has been determined as a function of solvent. When the chosen solvent is D20, the rate …

Bis[Μ-1,2-Bis(2-Pyridyl)Ethyne-K2N:N']Bis[Aquadinitratocadmium(Ii)], Badruz Zaman Md., Matthew J. Davis, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

Two twisted 1,2-bis(2-pyridyl)ethyne ligands bridge two Cd²⁺ centers in the C₂-symmetric title complex, [Cd₂(NO₃)₄(-C₁₂H₈N₂)₂(H₂O)₂]. The bridging ligands arch across one another creating a `zigzag loop' molecular geometry. Two nitrate ions and a water molecule complete the irregular seven-coordinate Cd-atom environment. The dihedral angles between the equivalent pyridyl ring planes of the two independent ligands are 67.2 (1)°. O_water-HO_nitrate hydrogen bonding creates two-dimensional layers parallel to the ab plane.

Formula: [Cd₂(NO₃)₄(C …

Pharmacophore Derivation Using Discotech And Comparison Of Semi-Emperical, Ab Initio And Density Functional Comfa Studies For Sigma 1 And Sigma 2 Receptor-Ligands, Dawoon Jung

Dissertations

This study describes the development of pharmacophore and CoMFA models for sigma receptor ligands. CoMFA studies were performed for 48 bioactive sigma 1 receptorligands using [H³ ](+) pentazocine as the radioligand, for 30 PCP derivatives for sigma 1 receptor-ligands using [³H](+)SK-F 10047 as the radioligand and for 24 bioactive sigma 2 receptor-ligands using the radioligand [H³](+)DTG in the presence of pentazocine. Distance Comparisons (DISCOtech) was used as the starting point for CoMFA studies. The conformers, derived by DISCOtech were optimized using AMi, or HF/3-21G* in Gaussian 98. The optimized geometries were aligned with the pharmacophore, …

Evaluation Of Fluorapatite As A Waste-Form Material: Third Quarter Report, March 1 - May 31 2003, Dennis W. Lindle, Dale L. Perry

Separations Campaign (TRP)

Fluorapatite, fluorinated calcium phosphate, has been identified as a potential matrix for the entombment of the zirconium fluoride fission product waste stream from the proposed FLEX process. If the efficacy of fluorapatite-based waste-storage can be demonstrated, then new and potentially more-efficient options for handling and separating high-level wastes, based on fluoride-salt extraction, will become feasible. This proposal will develop a dual-path research project to develop a process to fabricate a synthetic fluorapatite waste form for the ZrF₄, FP waste stream, characterize the waste form, examine its performance under environmental conditions, and correlate the behavior of the waste form …

Rnase L Mediates Transient Control Of The Interferon Response Through Modulation Of The Double-Stranded Rna-Dependent Protein Kinase Pkr, Khalid S.A. Khabar, Yunus M. Siddiqui, Fahad Al-Zoghaibi, Latifa Al-Haj, Mohammed Dhalla, Aimin Zhou, Beihua Dong, Mark Whitmore, Jayashree Paranjape, Mohammed N. Al-Ahdal, Futwan Al-Mohanna, Bryan R.G. Williams, Robert H. Silverman

Chemistry Faculty Publications

The transient control of diverse biological responses that occurs in response to varied forms of stress is often a highly regulated process. During the interferon (IFN) response, translational repression due to phosphorylation of eukaryotic initiation factor 2α, eIF2α, by the double-stranded RNA-dependent protein kinase, PKR, constitutes a means of inhibiting viral replication. Here we show that the transient nature of the IFN response against acute viral infections is regulated, at least in part, by RNase L. During the IFN antiviral response in RNase L-null cells, PKR mRNA stability was enhanced, PKR induction was increased, and the phosphorylated form of eIF2α …

Oxidation Behavior Of Zr-Cu-Al-Ni Amorphous Alloys In Air At 300～500 ℃, H. Hsieh H., Kai W., G. Neih T., Kawamura Y.

Journal of Electrochemistry

The oxidation behavior of the Zr_based bulk amorphous alloy (BMG; Zr_30Cu_10Al_5Ni in at.%) was studied in dry air over the temperature range 300～500 ℃. The kinetic results indicated that the amorphous alloy oxidized linearly at 300 ℃,while the parabolic oxidation was observed at 350～425 ℃, and the oxidation behavior at 500 ℃ was irregular and complicated. In general, the scales formed on the surface of the amorphous alloy were temperature_dependent, consisting of tetragonal_ZrO2 at 300　℃, and of mostly tetragonal_ZrO2 as well as minor amounts of monoclinic_ZrO2 and CuO at T≥350　℃.

Corrosion Behavior Of Mg_(1.85)Mm_(0.15)Ni Hydrogen Storage Alloy Modified By Electroless Cu In Ch_3oh·H_2o Solutions, Hua-Bin Yang, Hai-Chang Zhang, Hua Sun, Xiao-Dan Wang, Zuo-Xiang Zhou

Journal of Electrochemistry

The corrosion behavior of the Mg1.85Mm0.15Ni (Mm:Ce_rich mischmetal) alloy modified by electroless Cu coating in different CH3OH_H2O solutions has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. These results showed that the corrosion behavior was improved after electroless Cu. The potentiodynamic polarization and electrochemical impedance spectroscopy results showed that the alloy electrode had more promising anti_corrosion behavior after coated in a 40%CH3OH_H2O solution. The values of corrosion current density and electrode reaction resistance were 5.6 mA·cm-2(11.7 mA·cm-2 for uncoated alloy electrode) and 22.25 Ω·cm2 (1.99 Ω·cm2 for the uncoated alloy electrode), respectively.

Initial Stages Of Pd Deposition Onto Au(111) Electrodes From Pdso_4 Solution, Jing Tang, Petri M., Kibler L.A., Kolb D.M.

Journal of Electrochemistry

Metal thin films have attracted considerable interest in relation to catalysis, energy, material, corrosion and environmental protection. Pd thin film is capable of proton reduction and strong hydrogen absorption, which has shown electrocatalytic activity to the oxidation of small organic molecules. In this paper, in_situ STM measurements are performed to study the deposition process and the influence of the surface structure and anion adsorption. When Pd is deposited from PdSO4 solution on Au(111) in the UPD range, a monolayer of Pd with pseudomorphic (1×1) structure was formed on the substrate with induced (3×7) R19° SO2-4 adsorption. With decreasing potential the …

Microstructure And Electrochemical Characteristics Of The Anodic Film Formed On Aluminum Surface, Jeng-Kuei Chang, Chi-Min Liao, Chih-Hsiung Chen, Wen-Ta Tsai

Journal of Electrochemistry

The thickness, morphology, chemical composition, and crystallinity of the anodized film formed on aluminum were examined in a transmission electron microscope (TEM). Thin foil for TEM analysis was prepared by ultramicrotomy. The relationship between the microstructure and the electrochemical characteristics of the alumina film forming on the pure aluminum was discussed in this investigation. At the forming voltage less than 100V, the anodized films formed at 85 ℃in aqueous ammonium adipate electrolyte was amorphous in nature. Although the film resistance was increased with the forming voltage, its dielectric constant was not changed significantly. As the forming voltage exceeded 100V, crystalline …

Electrochemical Monitoring On The Deactivation Of A Metallic Oxide Anode, Li-Kun Xu, Shi-Zhe Song, Ting-Yong Wang, Guang-Zhang Chen

Journal of Electrochemistry

The process of accelerated life test of an IrO2/Ta2O5 coated titanium anode was monitored using cyclic voltammetry and electrochemical impedance spectroscopy.The vatiation with electrolysis time of anodic voltammetric charge Q*,the double layer capacitance Cdl,the oxide film resistance Rf and the charge transfer resistance Rct for oxygen evolution was measured.A deactivation mechanism was proposed based on the observation results.

A Bilayer Self-Assembled Membrane Electrode For Fluorescence And Its Electrochemical Characterization, Xiang-Ying Sun, Bin Liu, Yun-Bao Jiang

Journal of Electrochemistry

The bilayer membrane was assemblied on Au electrode by the electrostatic interaction between the fluorescence regent 1_naphthylamine diacetate acid(NADA) and DL_Cysteine. The SAMs electrode NADA/Cys/Au can be used as fluorescence and electrochemical sensor for metal ions. This paper states the electrochemical characterization of NADA/Cys/Au and SAMs' application in continous determination for Cu2+ and Ni2+.

Synthesis And Electrochemical Characteristics Of Nickel-Based Complex Oxide Li_Ani_(0.78)Co_(0.2)Cd_(0.02)O_2, Rong-Zhong Yuan, Mei-Zhen Qu, Zuo-Long Yu

Journal of Electrochemistry

The nickel_based complex oxide LiaNi0.78Co0.02O2 cathode materials for lithium_ion rechargeable batteries was synthesized by the improved solid_state reaction method with LiOH·H2O, ball_like Cd_doped Ni(OH)2 and Co2O3 as raw materials. The analysis ICP_AES proved that the as_prepared compounds were near the stoichiometric form. The XRD, SEM and electrochemical characteristics testing were also carried out. The results showed that the complex cathode material LiaNi0.78Co0.2Cd0.02O2 has layered structure, homogeneous surface distributions,uniform particles with good crystal morphology as well as stable electrochemical performances. At ambient temperature the resulted materials have a high reversible capacity and good cycling stability.Its highest initial reversible capacity is more …

Perfluorinated Sulfonic Acid Lithium Conductivity Humidity Sensor, Hong-Feng Xu, Jing Liu, Li Wan

Journal of Electrochemistry

Treat carbon paper with 3% PTFE solution and dried in 340 ℃ for 40 minutes to enhance its intension, and level off the surface of the carbon paper with a mixture of XC_72 carbon black and PTFE solution. With those treated carbon paper as electrodes,recast Nafion thin film from 5% Nafion solution as humidity sensitive material, a solid polymer electrolyte humidity sensor was prepared on a thin PET film.Take the relative humidity data from several saturated salt solutions, the relationship between conductivity response and relative humidity was studied at different relative humidies.The results showed: when the polymer electrolyte was H+ …

Effect Of Scn~- On The Transition Current Of Zn During The Electrodeposition Zn-Co Alloys, Ren-He Yin, Wei-Min Cao, Zheng-Hua Fang

Journal of Electrochemistry

For co_deposition of Zn_Co alloys at sufphate baths with micro_concentration of SCN- the transition current of Zn was found with the deposition process changing from normal Co_deposition to anomalous co_deposition, and the value of transition current increased with increasing SCN- concentration, but decreased with increasing value of pH. The existence of SCN- decreases the evolution overpotential of Co metal, but has no effects on the evolution overpotential of Zn metal and H2.

Recent Progress In The Research On Electrodeposition Of Composite Coatings, Xiao-Bing Liu, Xu-Cheng Wang, Yu Chen, Dan-Hong Cheng, Zu-Zhan Yu

Journal of Electrochemistry

Recent progress in the research on composite coatings prepared by electroplating technology is reviewed. The nanoscaled particles, electrocatalytic, photoactive composite coatings are emphatically discussed. The composite coatings prepared by dispersing nanoscaled particles could attain better hardness, wear resistance and corrosion resistance than those of composite coatings which prepared by adding micronscaled particles. As compared with pure metal electrode and alloy electrode, some electrocatalytic composite coatings electrode could markedly reduce the overvoltages of cathodic and anodic electrode reaction. In recent years, the electrocatalytic composite coatings which based on metal oxides and conductive polymer as matrix materials become a newest field of …

Preparation And Electrochemical Preformance Of Zn-La Alloys, Xian-Ling Meng, Hua-Bin Yang, En-Dong Yang, Xiao-Dan Wang, Hai-Chang Zhang, Jun-Hong Wang, Zuo-Xiang Zhou

Journal of Electrochemistry

Zn_La alloys were prepared by solid phase diffusion method and the effects of La on the electrochemical performance of zinc electrodes were investigated using potentiostatic polarization technique and charging/discharging cycle test. The results showed that adding La to zinc electrode remarkably suppressed the zinc dendrite, the shape of zinc electrode and zinc corrosion, and hence, markedly improved the cycle performance of zinc electrodes. The discharging capacity of the zinc electrode containing 0.5at.% La which was the optimum was still 520 mAh/g after it cycled 80s at the current of 100 mA. The XPS showed that La element mainly adhered on …

Cavitation Erosion Behavior Of Ni-Al Intermetallic Coatings, Chang J.T., H. Yeh C., He J.L., Chen K.C.

Journal of Electrochemistry

A cathodic arc plasma ion plating process was demonstrated to deposit Ni_Al film on AISI 1045 carbon steel to evaluate the cavitation protection. Three target materials with Ni52Al48, Ni60Al40, and Ni70Al30 compositions were used to reveal the microstructural of coatings. Experimental results show that the nickel content in these deposits increased with the nickel content of the target material. The major phase of deposited film was Ni3Al regardless of the target materials. All of the as_deposited films presented very strong adhesion and reflects their cavitation erosion behavior in fresh water. All coatings increased the cavitation erosion resistance of the bare …

Study Of Marine Biocorrosion Using Afm And Molecular Techniques, Herbert H.P.Fang, Lichong Xu, Tong Zhang

Journal of Electrochemistry

Biofilm is ubiquitous in nature.However,corrosin caused by biofilm is still by and large overlooked.This presentation is to demonstrate the applications of several newly developed analytical techniques in chemisrty and microbiology for the study of marine biocorrosion on steel.AFM(atomic force microscopy) was applied to investigate the initial formation mechanism of biofilm and the degree of corrosion of steel in polluted seawater.DNA/RNA_related molecular techniques were used to analyze the microbial composition corrosive biofilm. Results showed that microbial corrosion began within six days, and the corroded volume in the increased as a power function of time with an index 2.83. Most of the …

Selective Corrosion In Duplex Stainless Steel, Wen-Ta Tsai, Kuen-Ming Tsai, Chang-Jian Lin, Yan Fu

Journal of Electrochemistry

In duplex stainless steel, the two constituent phases, namely ferritic (α)and austenitic(γ) phases, have different crystal structure and chemical composition. They may thus exhibit different corrosion resistances in aqueous environment. In this investigation, an electrochemical technique with spatial resolution was employed to measure the potential difference between these two constituent phases in 2205 duplex stainless steel. Image analyzing techniques were also used to examine the preferential corrosion between α and γ phases. The experimental results showed that ferrite had a higher potential than austenite in0.01 mol/L NaCl solution. In 2 mol/L H2SO4+x mol/L HCl solution, two distinct peaks appeared in …

Metastable Pitting Of Aluminum Anodic Film In Neutral Sodium Chloride Solution, Jing-Mao Zhao, Zhi-Jun Bai, Yu Zuo

Journal of Electrochemistry

Potentiodynamic polarization,electrochemical noise and SEM were used to study the corrosion behavior of L2 aluminum anodic film in 1 mol/L NaCl solutions.The results showed that anodic oxidization of aluminum increases its corrosion resistance greatly.However metastable pits were also observed when the film was thin or was exposed to the solutions for a long time.These pits with a diameter less than 10μm often occurred around the metallic inclusions in film.

Corrosion Behavior Of Reinforcing Steel In Concrete Subjected To Chloride Contamination By Eis, Rong-Gang Hu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS) was employed to study the influence of chloride on the corrosion behavior of reinforcing steel in concrete.In Nyquist plot,the spectrum consists of two semicircles,indicating that the reinforced concrete system contained two time constants,one derived from electrical double layer of reinforcing steel and the other from the deposition film of concrete layer.The depressed semicircle in lower frequency featured the non_faradic behavior of the electrical double layer (EDL) deviated from idea capacitor due to diffusive effect which was attributed to the surface roughness of rebar and the inhomogenity of concrete layer.Then the EDL was denoted by a constant phase …

Conductance Properties For Electrolyte Of Lithium Ion Battery At Low Temperature, Jing-Li Han, Yan-Mei Yu, Jian Chen, Chun-Tong Wang

Journal of Electrochemistry

The system of LiPF6_ethylene carbonate (EC) _methy1 acetate (MA) was studied. The conductivities of this system were measured under various composition and various salt concentrations at temperature range of 20～-50 ℃. The optimum composition of this system was selected. The tests of cyclic voltammography and charge_discharge were carried out. This system was compared with commercial electrolyte solution.

Corrosion Prediction Of Carbon Steel In Concentrated Lithium Bromide Solutions At High Temperature Using Bp Neural Network, Nai-Bao Huang, Cheng-Hao Liang

Journal of Electrochemistry

Neutral network model has been developed for the computation of corrosion rate of carbon steel in LiBr solutions.The results indicate that the model is capable of reproducing the effects of changes in alkalinity,temperatures,LiBr and Na2MoO4 concentrations on the rates of general corrsion and good agreement between calculated and experimental corrosion rate is obtained.The model can be used to satisfactorily predict the corrosion rate of carbon steel in different concentrations of LiBr solutions containing different inhibitors at different temperatures.It also provides a novel method for corrosion monitoring of metals used in LiBr absorption chiller.

The Electrochemical Behaviors Of A Novel Ferrocene Alkylthiol Sams On Au Electrode, Xiao-Gang Zhang, Yan-Li Shi, Hu-Lin Li

Journal of Electrochemistry

A novel alkylthiol molecule containing ferrocene and pyridium moieties and its hydrogenated products were synthesized and subsequently assembled on Au electrode as SAMs. Cyclic voltammogram(CV) was used to investigate the structure_dependent electrochemical response of the SAMs in 0.1 mol/L HClO4 aqueous solution.