Physical Sciences and Mathematics Commons^™

Manganese Oxide Mineral Phases Produced At Room Temperature Under Acidic Conditions Investigated With Xrd, Tem, Sem, Eds, And Bet, Nancy R. Birkner

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis concerns characterization of synthetic manganese oxides belonging to mineral phases known as Birnessite and Cryptomelane. Presented here are the results of an experiment designed to examine the influence of sodium, potassium, chloride, and sulfate ions on the reduction of potassium permanganate under acidic conditions at room temperature to produce Birnessite and Cryptomelane. The experiments used KMnO4 as the source of Mn and the resulting Birnessite and Cryptomelane precipitates were washed with 18 Mn/cm NANOpure water at the end of syntheses. Several state-of-the-art solid state techniques were used to characterize the Mn-based oxide mineral phases. Based on the literature …

Identifying Biomarkers For Resistance To Novel Cisplatin Analogues In Human Lung, Breast And Prostate Cancers, Becky Michelle Hess

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cisplatin is a common therapeutic agent used in cancer treatment. Unfortunately, resistance to cisplatin in addition to severe side effects limits its use in cancer treatment. Two novel cisplatin analogues, 4DB and 4TB were shown to have varying cytotoxicity in lung, breast and prostate cancer cells. The hypothesis for this study states that the differences in 4DB and 4TB cytotoxicity among different tissue types is due to the type and efficiency of DNA repair mechanisms involved in response to these drugs.

To test the hypothesis, proteins involved in the rate limiting step of nucleotide excision repair (NER) and mismatch repair …

Evaluation Of Low-Temperature Fluoride Routes To Synthesize Actinide Nitrides And Oxide Solid Solutions, Gunanda Waduge Chinthaka Silva

UNLV Theses, Dissertations, Professional Papers, and Capstones

Actinide mononitrides have been considered as a possible nuclear fuel for the Generation-IV nuclear reactor systems. In the process of evaluating these actinide mononitrides as nuclear fuel, it is important to study different chemical and physical characteristics of these compounds. Synthesis of the materials is thus important. Carbothermic reduction is one of the techniques that have been used to synthesize actinide mononitrides. In this method, a mixture of actinide oxide such as UO ₂ and excess carbon is heat treated at temperatures greater than 1700 °C under a nitrogen atmosphere. The technique is however not promising in synthesizing the actinide …

The Synthesis And Systematic Evaluation Of Modified Polymeric Foams And Electrically Conductive Polyimide/Carbon/Metal Films, John Macharia Kinyanjui

UNLV Theses, Dissertations, Professional Papers, and Capstones

Thermally processed PU foams are examined as a function of processing temperatures (25, 45, 65, and 85°C) at the side, middle, and center of a simple cylindrical mold. The PU foams show both chemical and morphological differences as a function of the processing temperature and radial position within the mold. Thermal degradation of uretoneimine structures, the emergence of carbodiimide structures, and extent of reaction of isocyanate groups are measured using photoacoustic FTIR spectroscopy. Chemical gradients and morphology differences between the side, middle, and center of the molded foam are observed for all processing temperatures. The data indicate that thermal activation …

Water Quality Changes In A Constructed Wetland At The Springs Preserve In Las Vegas, Nevada, Aaron Mathis Miller

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Springs Preserve near downtown Las Vegas, Nevada contains a seven-acre constructed wetland. Springs Preserve managers are planning to use water from the constructed wetland to irrigate creeks immediately north of the wetland. These creeks will be used by a variety ofaquatic wildlife, including endangered amphibians sensitive to harmful metalloids, such as selenium, lead, and arsenic.

In an attempt to answer toxicological questions about contaminant concentrations in the constructed wetland, three metals and metalloids (selenium, arsenic, and lead), two nutrients (nitrogen and phosphorus), and the major ionic species were analyzed at four sampling locations for aqueous concentrations, in two separate …

Controlled Functionalization Of Crystalline Polyolefins And Their Application In Soluble Polymer Support, Jihoon Shin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Functionalization of polyolefins has been recognized as a useful methodology for the generation of new materials with a wide range of applications. Recently, crystalline or semi-crystalline polyolefins have drawn increasing attention in both industrial and academic fields as one of the most interesting engineering plastics, due to their remarkable physical and mechanical properties. This dissertation describes: (1) novel methods for the direct postfunctionalization of crystalline polyolefins to introduce functionality, (2) characterizations for the functionalized polymers to analyze their structures, molecular-weight properties, thermal properties, and hydrophilicity, and (3) an application of the modified crystalline polystyrene as a soluble polymer support for …

Substituent Effect On The Electronic And Assembling Properties Of Asymmetric Phenazine Derivatives, Bin Cao

UNLV Theses, Dissertations, Professional Papers, and Capstones

Currently, one-dimensional (1-D) nanostructures have drawn much interest because of their potential applications for nanoscale optoelectronic devices. Self-assembly (SA) based on π-conjugated systems through various intermolecular interactions has been widely used to produce 1-D nanostructure. Morphology of the assembled structures can be modified by incorporating substituents, which provide additional secondary interactions. Meanwhile, those substituents also influence the electronic properties of the molecules. Previous studies have made little effort to systematically study subsistent effects on both electronic and SA properties.

The primary objective of this research is to generate controllable 1-D structures through SA, and to provide a fundamental understanding of …

Evaluation Of Extraction Chromatography Resins For Rapid Actinide Analysis, Julie Marisa Gostic

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, physical and chemical parameters associated with extraction chromatography separation procedures were investigated for rapid actinide analysis. A vacuum box system was designed in-house and was characterized in terms of flow rate reproducibility, matrix effects on flow rate for sequential elution, and actinide separation efficiency using different types of resin (TEVA, DGA and TRU). Results indicated that the columnar kinetics of the resins were sufficiently rapid to run high purity samples through the unit over a wide range of flow rates for all resin types. Single matrix interferences at a metal ion ratio of 1:10 6 relative to …

Characterization Of Iron Oxide Thin Films For Photoelectrochemical Hydrogen Production, Kyle Eustace Nelson George

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solar energy is the most sustainable source of energy available. However, solar applications such as photovoltaic cells represent only a partial solution to weaning our dependence upon fossil fuels. Several methods of storing solar energy are currently being pursued, and chemical storage stands out as a promising option - combining design simplicity with high energy density, with hydrogen being particularly attractive because of its abundance and inherently clean nature. A monolithic Photoelectrochemical (PEC) device that produces hydrogen by electrolyzing water directly from sunlight has the benefit of utilizing "free" solar energy to drive the reaction.

Although α-Fe 2 O 3 …

Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.

We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …

Study Of Corrosion Of Materials In The Sulfur-Iodine Hydrogen Production Cycle, Thao Trung Ho

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen is of great interest since the availability of traditional fossil fuels is in decline. Strictly speaking, hydrogen is not a primary source of energy but is an energy carrier, since energy typically must be used from another source (electricity, natural gas, coal, etc.) to produce it. Of hydrogen production techniques, the Sulfur-Iodine thermochemical water splitting process (S-I cycle), which was proposed by General Atomics (GA), is promising with its simplicity and high efficiency. Most of the chemicals are recycled except water. However, the S-I cycle operates in a harsh, corrosive environment in the presence of a mixture of iodine …

Desert Varnish As An Indicator Of Modern-Day Air Pollution In Southern Nevada, Piotr Nowinski

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rock varnish, often called desert varnish, is a slow-growing, manganese-rich coating that accumulates on exposed rock surfaces. The mechanism of varnish formation is not fully understood, however, most authors agree that varnishes derive their components from the atmosphere. The main goal of this study was to demonstrate the potential use of desert varnish as a passive environmental monitor of present and past atmospheric pollution. Analysis of varnishes is a new field that can potentially provide records of pre-anthropogenic levels of atmospheric metals and other environmental pollutants. To evaluate the potential of desert varnish as an environmental monitoring tool, the following …

Analytical Method Development For Determination Of Volatile Organic Compounds In Calcareous Desert Soil, Mary F. Turner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil sample preservation for volatile organic compound analysis generally requires short sample holding times or preservation of the sample's chemical constituents with sodium bisulfate (NaHSO 4 ). Calcareous soils cannot be preserved using NaHSO4 because effervescence will promote the loss of analytes, and short holding times before analysis are not practical for remote sampling locations. An experimental approach was developed for determination of volatile organic compounds (VOCs) in soil that utilizes solid sorbents for sample preservation and solid-phase microextraction (SPME) sample preparation technique coupled with gas chromatography/mass spectrometry (GC/MS) for analysis. Solid sorbents are used to sequester readily extractable (vapor …

Optimization Of The Microprecipitation Procedure For Nuclear Forensics Applications, Lyndsey Renee Kelly

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microprecipitation has become one of the most widely used sample preparation techniques for alpha spectroscopy. Many factors during the precipitation process can affect the yield and energy resolution by adding unwanted mass to the sample. Current applications in nuclear forensics call for an optimization of energy resolution and yield in order to improve identification and quantify specific radionuclides. The purpose of this research is to determine the optimal parameters used for microprecipitation. The optimal solution temperature, precipitation time, carrier amount, and hydrofluoric acid amount are used to investigate the influence of varying the type of carrier, as well as, the …

Zirconia-Magnesia Inert Matrix Fuel And Waste Form: Synthesis, Characterization And Chemical Performance In An Advanced Fuel Cycle, Kiel Steven Holliday

UNLV Theses, Dissertations, Professional Papers, and Capstones

There is a significant buildup in plutonium stockpiles throughout the world, because of spent nuclear fuel and the dismantling of weapons. The radiotoxicity of this material and proliferation risk has led to a desire for destroying excess plutonium. To do this effectively, it must be fissioned in a reactor as part of a uranium free fuel to eliminate the generation of more plutonium. This requires an inert matrix to volumetrically dilute the fissile plutonium. Zirconia-magnesia dual phase ceramic has been demonstrated to be a favorable material for this task. It is neutron transparent, zirconia is chemically robust, magnesia has good …