Physical Sciences and Mathematics Commons^™

Nitrite Photochemistry In 2-Propanol/Water Solution, Joseph B. Binder '04

Honors Projects

Nitrite ion, a component of nitrogen oxide pollution, is an important source of free radicals in the environment. N02- absorbs ambient ultraviolet light to break into NO and 0-, and in environmental conditions, 0- is converted to hydroxyl radical, OH. Hydroxyl radical reacts with a wide variety of environmental pollutants, including hydrocarbons and nitrogen oxides, so its sources are of interest to environmental chemists. In order to investigate the processes of nitrite photochemistry, nitrite ion was photolyzed at 366 nm in 2-propanol/water solution. This mixed solvent system allows investigation of the effects of varying the solvent cage composition and scavenger …

Sensing Of Aqueous Phosphates By Polymers With Dual Modes Of Signal Transduction, Dmitry Aldakov, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

A new approach to sensing of aqueous phosphate-related anions based on chromogenic conductive polymers is demonstrated. This method utilizes synergy between low-level p-doping in a polythiophene polymer and hydrogen bonding to increase anion-sensor affinity. These chromogenic conductive polymers show anion-specific changes both in color and in conductivity upon increasing concentration of anions, thus providing two independent modes of signal transduction.

Determination Of Carbon Nanotube Modification By Tg-Ms And Pyrolysis-Gc/Ms, Quentin Lineberry

Masters Theses & Specialist Projects

Uniform dispersion of carbon nanotubes (CNTs) has been one of the major impediments to the full development of the incredible suite of properties offered by CNTs, specifically single-walled carbon nanotubes (SWNTs). However, investigators at NASA Langley and the National Institute of Aerospace Research have recently obtained (SWNTs) that are soluble in select solvents, including THF, DM Ac, and ODCB. The SWNTs were exposed to reagents used in cited fullerene modification chemistry in an attempt to produce soluble SWNTs. Upon further examination, it was determined that the intended functionalization had not occurred, and some other phenomenon was responsible for the SWNTs …

Fighting Antibiotic Resistance: The Dape-Encoded N-Succinyl-L, L-Diaminopimelic Acid Desuccinylase From Haemophilus Influenzae In A Dinuclear Metallohydrolase, Nathaniel J. Cosper, David L. Bienvenue, Jacob E. Shokes, Danuta M. Gilner, Takashi Tsukamoto, Robert A. Scott, Richard C. Holz

Chemistry Faculty Research and Publications

No abstract provided.

Heterogeneous Chemistry Involving Methanol In Tropospheric Clouds, A. Tabazadeh, Robert J. Yokelson, H. B. Singh, Peter V. Hobbs, J. H. Crawford, L. T. Iraci

Chemistry and Biochemistry Faculty Publications

In this report we analyze airborne measurements to suggest that methanol in biomass burning smoke is lost heterogeneously in clouds. When a smoke plume intersected a cumulus cloud during the SAFARI 2000 field project, the observed methanol gas phase concentration rapidly declined. Current understanding of gas and aqueous phase chemistry cannot explain the loss of methanol documented by these measurements. Two plausible heterogeneous reactions are proposed to explain the observed simultaneous loss and production of methanol and formaldehyde, respectively. If the rapid heterogeneous processing of methanol, seen in a cloud impacted by smoke, occurs in more pristine clouds, it could …

Binary Frontal Polymerization: Velocity Dependence On Initial Composition, John A. Pojman, Jerry A. Griffith, H. Archie Nichols

Faculty Publications

Frontal polymerization is a mode of polymerization in which a localized zone of reaction propagates through the coupling of thermal diffusion and the Arrhenius dependence of the reaction rate. The dependence of the front propagation velocity on the initial composition has been determined in initially miscible binary systems of a free-radically cured diacrylate and an amine- or cationically cured epoxy resin. A minimum of the velocity as a function of the monomer mole fraction is observed if the two polymerizations occur independently. Excellent agreement with an analytical description was found with the diacrylate and an amine-cured epoxy but not for …

Magnesium/Methanol: An Effective Reducing Agent For Peroxides , Peng Dai, Patrick Dussault, Tony K. Trullinger

Chemistry Department: Faculty Publications

Magnesium in methanol is an effective reagent for the chemoselective reduction of peroxides, including ozonides. Mg/MeOH is significantly more reactive than Me2S or PPh3 and somewhat more reactive than Zn/HOAc

Preparation Studies For Secondary Electron Emission Experiments On Superconducting Niobium, Anoop George, Robert A. Schill Jr.

Transmutation Sciences Materials (TRP)

Accelerator driven transmutation of waste is one complementary approach to deal with spent nuclear fuel as compared to permanent storage. High-energy protons generated by a particle accelerator collide with a heavy metal target producing neutrons. Long-lived radioactive isotopes interacting with the neutrons transmute into shorter-lived isotopes. To generate the high-energy protons efficiently, linear accelerators use multi-cell superconducting radio frequency (RF) cavities made of niobium. Superconducting niobium cavities have several advantages, including small power dissipation. The high electromagnetic fields present in these cavities may result in undesired field emission from surface imperfections with the probability of generating an avalanche of secondary …

Pictures From My Life With Polymer Science: Album 09, Otto Vogl

Otto Vogl

No abstract provided.

Afci Quarterly Input – Unlv January Through March, 2004, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

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.

New Magnetic Materials Obtained By Ion-Exchange Reactions From Non-Magnetic Layered Perovskites, H Kageyama, L Viciu, Gabriel Caruntu, Y Ueda, John B. Wiley

Chemistry Faculty Publications

New layered magnetic materials, (MCl)Ca2Ta3O10 (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa2Ta3O10 (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 Å and c = 15.533 Å for Cu, and a = 3.822 Å and c = 15.672 Å for Fe. Being separated by the Ca2Ta3O10 triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements …

The Creation Of Organic And Biological Nanostructures At Surfaces Using Scanning Probe Nanolithography, B. L. Weeks, Chin Li Cheung, J. J. De Yoreo

Barry Chin Li Cheung Publications

As the size of microelectronic devices continues to shrink and the desire to build in hierarchical structures of organic and biological materials grows, control of the chemistry and structure of materials at the molecular level will become increasingly important. Conventional lithographic techniques to pattern polymeric thin films are beginning to reach their resolution limit and several alternative "bottom-up" strategies have emerged that use the scanning probe microscope to manipulate matter at the atomic or molecular scale. Of these new scanning probe nanolithography (SPN) techniques, dip-pen nanolithography (DPN) [I] and scanning probe nanografting (SNG) [2] are particularly promising.

The DPN methodology …

An Evaluation Of Formic Acid As An Electron Donor For Palladium (Pd) Catalyzed Destruction Of Nitroaromatic Compounds, Mark R. Stevens

Theses and Dissertations

The Department of Defense is responsible for over 2,000 hazardous waste sites containing nitroaromatic compounds (NACs) such as 2,4,6-TNT, 2,4- and 2,6-DNT that resulted from the production and use of munitions throughout the nation and world, NACs are typically persistent in natural environments, though they can be oxidized or reduced under engineered conditions, NACs and their reduction products are toxic chemicals and suspected human carcinogens, Both TNT and 2,4-DNT are listed as priority pollutants by the U,S EPA, This study investigates the effectiveness of using a palladium (Pd) catalyst in concert with formic acid as an electron donor to reduce …

Reactivity Of (Bicyclo[5.1.0]Octadienyl)Iron(1+) Cations: Application To The Synthesis Of Cis-2-(2’-Carboxycyclopropyl)Glycines, Nathaniel J. Wallock, William A. Donaldson

Chemistry Faculty Research and Publications

The addition of carbon and heteroatom nucleophiles to (bicyclo[5.1.0]octadienyl)Fe(CO)₂L⁺ cations 5 or 8 (L = CO, PPh₃) generally proceeds via attack at the dienyl terminus on the face of the ligand opposite to iron to generate 6-substituted (bicyclo[5.1.0]octa-2,4-diene)iron complexes (11 or 13). In certain cases, these products are unstable with respect to elimination of a proton and the nucleophilic substituent to afford (cyclooctatetraene)Fe(CO)₂L (4 or 7). Decomplexation of 13f, arising from addition of phthalimide to 8, gave N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (19). Oxidative cleavage of 19 (RuCl …

The Electrochemical Separation Of Curium And Americium: Quaterly Report January - March 2004, David W. Hatchett, Kenneth Czerwinski

Separations Campaign (TRP)

This research report outlines the current status and progress associated with the electrochemical separation of Curium and Americium.

Data collection and analysis of the Ce³⁺/Ce⁴⁺ redox couple in various supporting electrolytes has continued. All electrolyte systems were investigated at Pt, Au, and Glassy Carbon working electrodes. Analysis of these data was accomplished by performing appropriate background subtractions to reveal net peaks due to Ce redox behavior. Successful identification of the Ce redox couple was achieved with all electrolyte/electrode systems, although a decline in peak resolution was observed with increasing acid concentration. Optimal conditions in this experiment were …

Inside Unlv, Katrina Hudak, Carol C. Harter, James Frey

Inside UNLV

No abstract provided.

Aerobic Biodegradation Of Alternative Fuel Oxygenates In Unsaturated Soil Columns, Kevin A. Mares

Theses and Dissertations

Groundwater contamination problems caused by methyl-tertiary butyl ether (MTBE) in subsurface waters have prompted the search for a gasoline oxygenate replacement. In order to avoid the problems encountered with MTBE, it is prudent to evaluate the fate and transport in the subsurface of proposed replacements, such as ethanol. In this study, ethanol transport and degradation in unsaturated soil was investigated using a series of eight soil columns. This preliminary study was to see if the soil column system components functioned properly, how similarly the eight soil columns performed, and if soil oxygen concentration affected degradation of ethanol. Tracer tests, using …

Characterization Of Chlorinated Solvent Degradation Profile Due To Microbial And Chemical Processes In A Constructed Wetland, Teresa A. Sobolewski

Theses and Dissertations

Perchloroethene (PCE) and its degradation products are among the most common organic groundwater contaminants in the United States. Constructed wetlands are a relatively new approach to dealing with this contamination problem. With their upward flow capability it is possible to introduce an aerobic and anaerobic environment with a consortium of microorganisms available to degrade the contaminants to within acceptable levels established by the Environmental Protection Agency (EPA). This study is a follow-up to the previous two years of research on PCE degradation in cell 1 at Wright-Patterson Air Force Base. This thesis was conducted in order to study the wetland …

An Evaluation Of Formate As An Electron Donor To Facilitate Palladium (Pd) - Catalyzed Destruction Of Chlorinated Aliphatic Hydrocarbons, Matthew D. Welling

Theses and Dissertations

Chlorinated aliphatic hydrocarbons (CAHs) such as trichloroethylene (TCE), tetrachloroethylene (PCE), and trichloroethane (TCA) are probable human carcinogens that have been used widely within the DoD, primarily as solvents for cleaning and metal degreasing. These compounds are frequently found to be groundwater contaminants. In fact, TCE and PCE are the first and third most commonly detected groundwater contaminants nationwide. The focus of this study was to determine the effectiveness of using a palladium (Pd) catalyst with formate as a reductant to treat CAH-contaminated groundwater. TCE was used as a model CAH. Other investigators have focused on hydrogen gas (H₂) …

Red-Green-Blue Emission From Tris(5-Aryl-8-Quinolinolate)Al(Iii) Complexes, Radek Pohl, Victor A. Montes, Joseph Shinar, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

A simple yet effective strategy for synthesis of 5-aryl-8-quinolinolate-based electroluminophores with tunable emission wavelengths is presented. Two different pathways for the attachment of electron-donating or electron-withdrawing aryl groups to the 5-position of the quinolinolate ligand via Suzuki coupling were developed. A successful tuning in the emission color was achieved: the emission wavelength was found to correlate with the Hammett constant of the respective substituents, providing a powerful strategy for prediction of the optical properties of new electroluminophores.

Triethylammonium Tetraphenylborate Dichloromethane Solvate, Daron E. Janzen, Kent R. Mann

Daron E Janzen, Ph.D.

No abstract provided.

Infrared Laser Spectroscopy Of Jet Cooled Cobalt Tricarbonyl, Kyle Trauth, William A. Burns, Ginger Berry, Scott Reeve

Scott Reeve

No abstract provided.

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Task V: First Quarterly Report 01/12/04-02/29/04, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The Lead-Bismuth eutectic (LBE) has been determined from previous experimental studies by the Russians and the European scientific community to be a potential material that can be used as a spallation target and coolant for the TRP proposed application. Properly controlling the oxygen content in LBE can drastically reduce the LBE corrosion to structural steels. However, existing knowledge of material corrosion performance was obtained from point-wise testing with only very sparse experimental data. Scientists have noticed that the concentration of oxygen dissolved in the liquid alloy could control the corrosion rate of steels exposed to Pb or Pb-Bi. At high …

Progress In Research For Biofuel Cell, Yue Bao, Xia-Qin Wu

Journal of Electrochemistry

In this article, research progresses of the biofuel cell in recent years were summarized. The operation principle and classification of the biofuel cells were described. The role of the mediator for promoting electron transfer in biofuel cells and the techniques for improving the electric properties of biofuel cells, such as output potential, were discussed with some attracting research instances. Finally, the choke points for research of biofuel cell were explored, and the application prospect of biofuel cells was forecasted.

Template Synthesis Of Highly Ordered Monocrystalline Metal Nanowire Arrays By A Two-Step Ac Electrodeposition, Juan Xiang, Jing-Hua Tian, Zi-Mian Ni, Zhi-Feng Huang, Bo Liu, Zhong-Qun Tian

Journal of Electrochemistry

The monocrystalline metal nanowire arrays were prepared by using a two-step AC electrodeposition in porous anodic aluminum oxide (AAO) template. The growth mechanism of nanowires was discussed. As a result, it has been found that the second voltage pulse has a considerable effect on the pore-filling ratio, the uniformity and the crystal structure, whereas the initial voltage pulse affects only the pore-filling ratio. Using the two-step AC electrodeposition, a highly ordered monocrystalline metal nanowire arrays with a pore-filling ration above 95% can be easily obtained.

An Electrochemical Study Of The Effects Of Chelating Agents And Additives On Electroless Copper Plating, Xin Gu, Zhou-Cheng Wang, Chang-Jian Lin

Journal of Electrochemistry

In this study, ethylenediaminetetraacetic acid disodium salt (Na_2EDTA), triethanolamine(TEA), and 2,2′-dipyridine were adopted as chelating agents or additives in the electrolyte for electroless copper plating, and formaldehyde (HCHO) was as the reducting agent. Linear sweep voltammetry was applied to analyze the polarization behavior. The peak current of formaldehyde oxidation which increased by the addition of 2,2′-dipyridine is beneficial to formaldehyde oxidation in a specific range of concentration, While TEA decreased the peak current of formaldehyde oxidation. Two cathodic peaks due to copper(Ⅱ)reduction of TEA chelatation and copper(Ⅱ)reduction of EDTA chelatation were examined. EDTA increased the reduction peak current of Cu-EDTA …

Study Of Sptfs/Ptfe Composite Membranes With Different Ews, Yong-Zhu Fu, Dan-Min Xing, Bao-Lian Yi, Hua-Min Zhang

Journal of Electrochemistry

In this paper, sPTFS/PTFE composite membranes for PEMFC were obtained by impregnating two kinds of sulfonated poly-α,β,β- trifluorostyrene resin with different EWs into the porous PTFE substrate membranes. Water uptake, proton conductivity, mechanical strength and fuel cell performance of these two composite membranes were measured. Water uptake and proton conductivity were greatly reduced and mechanical strength was increased by composition in comparison with homogeneous membranes. Under the operating condition: T_(Cell)=80 ℃, P_(H_2)=0.2　MPa,P_(O_2)=0.2　MPa, fuel cell performance of the two composite membranes were better than that of Nafion~115. The fuel cell performance of composite membrane with low EW was better …

Study On The Electrochemical Impedance Spectroscopy (Eis) Of Al-Bronze At Different Anodic Potentials, Hui Yu, Sa-Ying Dong, Hai-Bo Xu, Ming-Xian Sun

Journal of Electrochemistry

The corrosion dissolution mechanism of Al-bronze has been investigated by Electrochemical Impedance Spectroscopy (EIS) at different anodic potentials. In the active region, the corrosion products are complex compounds of cupreous chloride and the diffusion of CuCl~(-)_2 is the control process of electrochemical reaction. In the transition region, there exhibits two capacitance loops on EIS because CuCl and cupreous oxides films deposit on the electrode surface. In the limiting current region, an inductance loop appears on the EIS because the breakdown of the oxides film leads to serious pit corrosion.

Studies On The Mechanism Of Electroreduction Of Oxalic Acid, Yu Zhan Li, Xin Liu, Rui Sheng Hu, Deng Ping Gu

Journal of Electrochemistry

The electroreduction mechanism of oxalic acid on Pb electrode in Na_2SO_4 solution were investigated using high scan rate cyclic voltammetry and chronoamperometry. The dynamic parameters for the first step electron transter reaction of oxalic acid electroreduction by were determined. The corresponding reduction peak potentials of oxalic acid, glyoxylic acid and glycolic acid in the cyclic voltammogranis obtained in the same condition were compared, and the intermediate reduction products of oxalic acid were suggested. The results showed that oxalic acid is weakly absorbed on the lead electrode.

The Interaction In Doping Lithium Of Carbonaneous Anode In Lithium Ion Battery, Chang-Guo Chen, Hong-Min Zhang, Jia Chen, Dan-Mei Yu

Journal of Electrochemistry

The quantum chemical DV-X_α method was used to calculate the lithium-doped models from one-Li-dopant to LiC_6 and LiC_2. It was found that Li~+ has an tendency to attract electrons from the carbon plane through the C_6 hexagons lying above or below it by the graph of charge-density difference. It was shown that LiC_6 can exist steadily,while LiC_2 can not exist steadily.