Chemistry Commons^™

The Electroanalytical Performance Of Sonogel Carbon Titanium (Iv) Oxide Electrodes Versus Conducting Polymer Electrodes In The Electrochemical Detection Of Biological Molecules, Jelynn A. Stinson

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The electrochemical performance of a newly developed sonogel carbon titanium (IV) oxide (SGC/TiO2 ) electrode against poly(3-methylthiophene) (P3MT) and poly(2,2'-bithiophene) (PBTP) modified electrodes in the electrochemical detection of biological molecules is reported. The stability of the Titanium (IV) Oxide coating on the sonogel carbon electrode was shown to be greater than the P3MT coating on the conventional size glassy carbon electrode. After 10 consecutive scans, there was a 21% loss of the initial signal at the P3MT modified electrode and a 5% loss of the initial signal at the SGC/TiO2 electrode. The influence of NAD+ on NADH response was tested. …

Laser Initiated Chain Reactions: The Kinetics Of The Chlorine/Cyclohexane/Oxygen Chain System, Robert Alan Forlines

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The combination of laser photolysis with infrared chemiluminescence detection has proven an effective technique for determining the propagation rate coefficients of halogen + RH chain reactions. This thesis will extend the technique to cyclic alkanes by determining the propagation rate coefficients of the Cl₂/ cyclohexane chain system as well as the rate coefficient for the primary chain termination mechanism, R + O₂ → RO₂. The following reaction scheme is supported by the kinetic analysis: Cl₂ → 2Cl Laser Photolysis Cl + RH → HCl(v) + R First Propagation Step (k₁) R + …

Single -Walled Carbon Nanotubes Separation And Redox Chemistry And Their Applications For Optical Biosensing And Scaffold Materials, Xiaomin Tu

Theses and Dissertations

Single-walled carbon nanotubes (SWNTs) have drawn great attention worldwide for their unique electronic, mechanical and optical properties. This dissertation details studies of some of the most important areas including: (1) Single-stranded DNA (ssDNA) assisted separation of SWNTs using high performance liquid chromatography; (2) Optical sensitivity and kinetic studies of redox reaction of ssDNA functionalized SWNTs with hydrogen peroxide (H 2 O 2 ); (3) Effects of Ag + on the redox reaction of ssDNA-encased SWNTs with hydrogen peroxide; (4) Single-walled carbon nanotube based optical sensors for DNA detection; and (5) SWNTs as scaffolds for promoting stem cell differentiation into bone …

Electrochemical Studies Of Some Furyl, Indol, Pyrrol, Hydroxynapthyl And Thienyl Derived Sulfonamides And Their Antibacterial Activities, Raja S. Machana

Theses and Dissertations

Sulfonamides are synthetic, wide-spectrum, antibiotics that find current therapeutic applications in the treatment of urinary tract infections, nocardiosis, and toxoplasmosis. Rapid development of bacterial resistance to this class of antimicrobial agents has obligated the need for synthesis of new sulfonamide derivatives. N 1 substitution with heterocyclic moieties produced variable antibacterial efficacies and their structure activity relationships were fairly established. However, para-amino (the N of which is designated as N 4 ) sulfonamide derivatives are less commonly studied. In this research we have selected a series of para-amino sulfonamide derivatives. Since redox potentials are important in determining the physiological activity of …

Dissociation Of Eif1 From The 40s Ribosomal Subunit Is A Key Step In Start Codon Selection In Vivo, Sarah F. Mitchell

Chemistry and Biochemistry Faculty Works

Selection of the AUG start codon is a key step in translation initiation requiring hydrolysis of GTP in the eIF2·GTP·Met-tRNA iMet ternary complex (TC) and subsequent Pi release from eIF2·GDP·Pi. It is thought that eIF1 prevents recognition of non-AUGs by promoting scanning and blocking P i release at non-AUG codons. We show that Sui? mutations in Saccharomyces cerevisiae eIF1, which increase initiation at UUG codons, reduce interaction of eIF1 with 40S subunits in vitro and in vivo, and both defects are diminished in cells by overexpressing the mutant proteins. Remarkably, Sui? mutation ISQLG93-97ASQAA (abbreviated 93-97) accelerates eIF1 dissociation and Pi …

Flavin Charge Transfer Transitions Assist Dna Photolyase Electron Transfer, Spiros S. Skourtis, Tatiana Prytkova, David Beratan

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

This contribution describes molecular dynamics, semi-empirical and ab-initio studies of the primary photo-induced electron transfer reaction in DNA photolyase. DNA photolyases are FADH−-containing proteins that repair UV-damaged DNA by photo-induced electron transfer. A DNA photolyase recognizes and binds to cyclobutatne pyrimidine dimer lesions of DNA. The protein repairs a bound lesion by transferring an electron to the lesion from FADH−, upon photo-excitation of FADH− with 350–450 nm light. We compute the lowest singlet excited states of FADH− in DNA photolyase using INDO/S configuration interaction, time-dependent density-functional, and time-dependent Hartree-Fock methods. The calculations identify the lowest singlet excited state of FADH− …

Solution Conformations Of Three Small Cluster Oligosaccharide Mimetics (Scom) From D-Glucosamine, D-Altrosamine, And (-)-Quinic Acid, Q. L. Nguyen, L. Olmstead, S. Bains, Andreas H. Franz

College of the Pacific Faculty Articles

Three small cluster oligosaccharide mimetics were synthesized, and their CDCl3 solution conformations were determined with NMR experiments. In this paper, we confirmed conformational similarities in rings A and B in all three compounds, and we provide the overall solution geometries. In all cases, an unusual cyclohexane twist-boat conformation with longrange 4 J-(W)-coupling was observed. The origin of the bias towards the twist-boat was attributed primarily to the fused ring system between the cyclohexane ring and the dioxacyclopentane (acetal) including hydrogen bonding. Temperature-annealed molecular dynamics simulations complemented the NMR experiments and supported the overall assignment.

Hydration Studies Of Electrospray Ions From Amino Acids And Small Peptides, Chuong Quoc Nguyen

Theses and Dissertations

This project was undertaken to gain a better understanding of the hydration behaviors of gas phase ions from solutions containing amino acids and peptides. In order to characterize their hydration behavior, the molecules of interest in solutions were first converted into gas phase ions by electrospray ionization (ESI). The completely desolvated ions were then deliberately dispersed into an inert bath gas, usually nitrogen, containing accurately known concentrations of solvent vapor. The resulting mixtures of ions and bath gas were subsequently passed into a vacuum chamber by way of an adiabatic supersonic free jet expansion. The cooling during that expansion caused …

Synthetic Approach To Epibatidine From 1-(Phenylsulfonyl)Pyrrole, Brandon G. Vanness

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The goal of this research was to synthesize the natural product epibatidine, a non-opiate analgesic and nicotinic acetylcholine agonist isolated from Epipedobates tricolor. A synthetic pathway utilizing a Diels-Alder cycloaddition of a 3-pyridyl substituted pyrrole and tosylacetylene was conceived based upon the original mass spectral fragmentation pathway of epibatidine determined by Daly. Although this pathway had been previously attempted using 1-(triisopropyl)-3-[5-(2-chloropyridyl)]pyrrole in the key Diels-Alder step, the lack of cycloadduct suggested that a pyrrole with a more electron withdrawing protecting group was required for this step. Therefore, synthesis of 1-(phenylsulfonyl)-3-[5-(2-chloropyridyl)]pyrrole via a palladium catalyzed cross-coupling reaction of 1-(phenylsulfonyl)-3-pyrroline and …

Synthesis And Electrical Properties Of Fluorenyl Polyesters Incorporating Diamond Fragments, Kevin John Wiacek

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Based on the paradigm of diamond as a wide band-gap electrical insulator, molecular counterparts to crystalline diamond (cyclohexane, adamantane, and diamantane) were incorporated into a high-temperature fluorenyl polyester (FPE) with the intent of increasing the breakdown strength. The effect of incorporating a CycloteneTM thermoset as a crosslinking agent to increase the dielectric strength and the self-healing phenomena of these polymers were also investigated. Polymers were synthesized using 9,9-bis(4-hydroxyphenyl)fluorene and the diacid chloride of cyclohexane, adamantane, and diamantane. Thin films of the polymers were cast from chloroform and the electrical properties were investigated. The polyester incorporating the largest diamond fragment had …

Synthetic Routes To A Fused-Ring Sydnoquinazoline, Gregory Edmond Storer

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In this research, 5-methylsydno-[3,4-a]quinazoline was synthesized via multiple methodologies, the best of which yielded the target compound in 50 % overall yield for the six steps. Synthesis of this compound in reasonable yields and exploration of its chemical behavior is of particular interest as a putative NO-prodrug. As an initial approach to the synthesis and accumulation of the compound of interest, attempts were made to optimize the existing synthetic pathway to its precursors. The starting material, 3-(2-acetylphenyl)sydnone, was prepared in 3 steps from commercially available starting material in good yields. This sydnone compound was then converted to the versatile intermediate, …

Modifiable Poly(Arylene Ether)S And Hyperbranched Poly(Esters), Brian Scott Werry

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Two different polymer systems have been studied in regards to their potential for functionalization to introduce new characteristics to the polymer. The first polymer system is a poly(arylene ether) with a truly pendant sulfone group from the monomer 3,5-difluorodiphenylsulfone. The work entails incorporating a bromine moiety onto the monomer for the versatile ability to bring in functional groups prior to or post the polymerization. The introduction of bromine onto the pendant ring had the best results from electrophilic bromine addition using N-bromosuccinimide in a mixture of sulfuric acid and acetic acid (80:20) yielding 76% of the desired material. Incorporation of …

Laser Induced Fluorescence Spectroscopy Of Molecular Bromine: Observations Of Emission To High Vibrational Levels In The Ground (X) State, David Jonathan Postell

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The Laser Induced Fluorescence spectrum of the B - X system of molecular bromine was recorded using a Red and Near Infrared sensitive PMT coupled to a scanning monochromator. A 543 nm HeNe laser was used to excite three resonances. Assignment of those resonances was made. A line narrowed Nd:YAG laser was used to excite eight fluorescence progressions, six from the (79,81) bromine isotopomer and one each from the (79,79) bromine and (81,81) bromine isotopomers. Analysis of the visible bands helped determine the resonances excited by the Nd:YAG laser. Fluorescence in the near infrared region, 9500 - 14000 angstroms, was …

Hydrophobically Modified Polyethyleneimines And Ethoxylated Polyethyleneimines, Michael Joseph Simons

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The modification of the commercially available polymers polyethyleneimines and ethoxylated polyethyleneimines took place with approximately a 3-10% alkylbromide modification followed by, in the case of the polyethyleneimines, a 2-hydroxypropyl modification, using propylene oxide, on the order of 65-70%. The objective was to increase the hydrophobicity of the polymer while keeping the cloud point above 60°C. Another approach taken was to form hydrophobic ethers from ethoxylated polyethyleneimine. We also added a 2-hydroxy ethyl group to a hexylated polyethyleneimine avoiding the use of ethylene oxide or drying EPI.

Tailoring Branching For Poly (Arylene Ether)S Via Reactivity Ratio Controlled Polymerizations, Amanda Ike

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The ability to control physical and mechanical properties of polymer systems has become an important aspect of polymer science. In order to tailor the branching in polymer systems, an understanding into the reactivity of the electrophilic sites in the monomer is important. Kinetic methods have been explored in order to determine the reactivity of monomers in preparing poly(arylene ether)s and to predict the degree of branching that will occur in a polymer of this kind. The reactivity of AB2 sulfones and phosphine oxides was explored, along with the reactivity of ABB'B'' sulfones. NMR spectroscopy was used as a probe into …

Simple Descriptors For Modeling The Solubility Of Gases, Alcohols, And Halogenated Hydrocarbons In Water, Sule Sidigu

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The Statmost, QSARIS, Excel, and SAS programs were used to model the solubility of gases, alcohols, and halogenated hydrocarbons in water using simple physical and topological descriptors. The alcohols were well-modeled using measures of the number of carbons, terminal methyls, and steric hindrance about the hydroxyl group. Molecular mass, boiling point, and critical volume or critical pressure were the best descriptors for the halogenated hydrocarbons. Critical pressure was the most applicable single descriptor for the gases. Molecular mass and boiling point also yielded good results for the gases and halogenated hydrocarbons when regressed together.

Formation Of A Sydno[3,4- A]Indolone And Reactions Thereof, Ryan Christopher Vikan

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In the present work, a synthetic route to the formation of a sydno[3,4- a]indolone was explored in the hope of attaining the first example of a fused-ring sydnone with an sp2-hybridized bridge. Formation of this product and exploration of its chemical behavior was anticipated to be of particular interest to the formation of NO-releasing prodrugs. A direct synthetic pathway to yield the target sydnoindolone starting from 3-(2-methoxycarbonylphenyl)sydnone and reaction with a base was proposed and explored. Attempted formation and isolation of the target sydnoindolone proved impossible under a variety of different conditions, undoubtedly due to the instability of this …

Incompressible And Compressible Boundary Layers On A Fibre In The Melt Spinning Process, John Harding

Doctoral

This thesis seeks to investigate shear stress on and heat transfer from the surface of a fibre in the industrial process of melt spinning. Melt spinning is the process whereby molten polymer materials are extruded through the holes of a device known as a spinneret to create continuous filaments of polymer. Fibres manufactured in this way are used in applications as diverse as fashion and clothing, to telecommunications. The magnitude ofthe shear stress on the fibre surface, and also the rate of heat transfer from the fibre to the surrounding environment are of major importance to the overall quality of …

Structure And Biosynthesis Of Heat-Stable Antifungal Factor (Hsaf), A Broad-Spectrum Antimycotic With A Novel Mode Of Action, Fengan Yu, Kathia Zaleta-River, Xiangcheng Zhu, Justin Huffman, Jeffrey C. Millet, Steven D. Harris, Gary Y. Yuen, Xing-Cong Li, Liangcheng Du

Department of Chemistry: Faculty Publications

A screen for antifungal compounds from Lysobacter enzymogenes strain C3, a bacterial biological control agent of fungal diseases, has previously led to the isolation of heat-stable antifungal factor (HSAF). HSAF exhibits inhibitory activities against a wide range of fungal species and shows a novel mode of antifungal action by disrupting the biosynthesis of a distinct group of sphingolipids. We have now determined the chemical structure of HSAF, which is identical to that of dihydromaltophilin, an antifungal metabolite with a unique macrocyclic lactam system containing a tetramic acid moiety and a 5,5,6-tricyclic skeleton. We have also identified the genetic locus responsible …

Corrosion Studies On The Uss Arizona With Application To A Japanese Midget Submarine, Brent M. Wilson, Donald L. Johnson, Hans Vantilburg, Matthew A. Russell, Larry E. Murphy, James D. Carr, Robert J. De Angelis, David L. Conlin

Department of Chemistry: Faculty Publications

The assessment of corrosion on the USS Arizona included the pioneering development of a minimum-impact cost-effective technique to determine the corrosion rate of steel-hulled shipwrecks in seawater. The technique, with potential application worldwide, is illustrated in this paper with the application to a World War II Japanese midget submarine submerged in deep waters off the Oahu, Hawaii, coast.

Dna Multiplex Hybridization On Microarrays And Thermodynamic Stability In Solution: A Direct Comparison, Daniel J. Fish, M. Todd Horne, Greg P. Brewood, Jim P. Goodarzi, Saba Alemayehu, Ashwini Bhandiwad, Robert P. Searles, Albert S. Benight

Chemistry Faculty Publications and Presentations

Hybridization intensities of 30 distinct short duplex DNAs measured on spotted microarrays, were directly compared with thermodynamic stabilities measured in solution. DNA sequences were designed to promote formation of perfect match, or hybrid duplexes containing tandem mismatches. Thermodynamic parameters DeltaH degrees , DeltaS degrees and DeltaG degrees of melting transitions in solution were evaluated directly using differential scanning calorimetry. Quantitative comparison with results from 63 multiplex microarray hybridization experiments provided a linear relationship for perfect match and most mismatch duplexes. Examination of outliers suggests that both duplex length and relative position of tandem mismatches could be important factors contributing to …

Highly Correlated Lanthanide Intermetallic And Oxide Phases: Crystal Growth And Structure-Property Relationships, Jasmine N. Millican

LSU Doctoral Dissertations

Our primary research goals are to synthesize, characterize, and study the structure, dimensionality, and physical properties of new highly correlated electron materials. Intermetallic lanthanide and oxide phases are of great interest due to their fascinating array of structural features and physical property phenomena, such as heavy fermion behavior, superconductivity, and magnetism. The crystal growth, structure, and physical properties of several different classes of materials, such as the Ln-M-Ga (Ln = La, Ce, Pr, M = Ni, Pd), Yb5Pt9, and R2Ir2O7 (R = Pr, Eu) compounds, will be highlighted within. The Ln-M-Ga phases allow us to examine the influence of the …

Understanding Charged Aerosol Detection With High Performance Liquid Chromatography, Brian John Forsatz

Seton Hall University Dissertations and Theses (ETDs)

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Sulfite Reduction In Mycobacteria, Rachel Pinto, Joseph S. Harrison, Tsungda Hsu, William R. Jacobs Jr., Thomas S. Leyh

College of the Pacific Faculty Articles

Mycobacterium tuberculosis places an enormous burden on the welfare of humanity. Its ability to grow and its pathogenicity are linked to sulfur metabolism, which is considered a fertile area for the development of antibiotics, particularly because many of the sulfur acquisition steps in the bacterium are not found in the host. Sulfite reduction is one such mycobacterium-specific step and is the central focus of this paper. Sulfite reduction in Mycobacterium smegmatis was investigated using a combination of deletion mutagenesis, metabolite screening, complementation, and enzymology. The initial rate parameters for the purified sulfite reductase from M. tuberculosis were determined under strict …

Nitroreductase: Evidence For A Fluxional Low-Temperature State And Its Possible Role In Enzyme Activity, Peng Zhang

University of Kentucky Doctoral Dissertations

The enzyme nitroreductase (NR) catalyzes two-electron reduction of high explosives such as trinitrotoluene (TNT), a wide variety of other toxic nitroaromatic compounds, as well as riboflavin derivatives, using a tightly-bound flavin mononucleotide (FMN) cofactor. It has important environmental and clinical implications. Previous studies have focused on elucidating NRs catalytic mechanism and solving its crystal structure.

In this dissertation work, we first develop and implement new strategies for labeling NR with stable isotopes, and report a completely re-designed protocol for NRs purification. Then we report the successful assignment of over half of NRs backbone resonances using 3d-NMR methods. The most significant …

Oxidative Dna Damage In Mild Cognitive Impairment And Late-Stage Alzheimer's Disease, Mark A. Lovell, William R. Markesbery

Chemistry Faculty Publications

Increasing evidence supports a role for oxidative DNA damage in aging and several neurodegenerative diseases including Alzheimer's disease (AD). Attack of DNA by reactive oxygen species (ROS), particularly hydroxyl radicals, can lead to strand breaks, DNA–DNA and DNA–protein cross-linking, and formation of at least 20 modified bases adducts. In addition, α,β-unsaturated aldehydic by-products of lipid peroxidation including 4-hydroxynonenal and acrolein can interact with DNA bases leading to the formation of bulky exocyclic adducts. Modification of DNA bases by direct interaction with ROS or aldehydes can lead to mutations and altered protein synthesis. Several studies of DNA base adducts in late-stage …

Improved Nitrate Sensing Using Ion Selective Electrodes Based On Urea–Calixarene Ionophores, Benjamin Schazmann, Dermot Diamond

Articles

Urea–calix[4]arenes 1 and 2 were synthesised and incorporated into ISE membranes for assessment as sensors for inorganic anions in water. 1 revealed a strong response to all anions following the Hofmeister selectivity order. For ISEs of 2, the response to a portion of the anion series was suppressed, increasing the margin of selectivity of nitrate over chloride, a common interferant of nitrate in fresh and marine water samples. The performance of ISEs containing 2 was compared to commercially available alkylammonium nitrate ion-exchange salts used for nitrate sensing. Our ISEs performed favourably in terms of sensitivity, linear range and LOD performing …

University Of Nevada, Las Vegas Transmutation Research Program Annual Report Academic Year 2006-2007, Anthony Hechanova, Rebecca Arbour

Transmutation Research Program Reports (TRP)

It is my pleasure to present the UNLV Transmutation Research Program’s sixth annual report that highlights the academic year 2006-2007. Supporting this document are the many technical reports and theses that have been generated over the past five years.

In the sixth year of our program, we continued to see growth in the Radiochemistry Ph.D. program with a total of 13 students in the third year of the program (we anticipated eight in the program proposal). Since our inception, the program has sponsored to their conclusion 42 M.S. and 4 Ph.D. degrees. The program supported 39 graduate students, 17 undergraduates, …

Investigation Of Optical Spectroscopy Techniques For On-Line Materials Accountability In The Solvent Extraction Process, Gary Cerefice, Kenneth Czerwinski

Safeguards Campaign (TRP)

The goal of this project is to evaluate the application of these analytical techniques to the on-line, real-time measurement of the actinide elements in the process streams of a solvent extraction process, with particular attention to the UREX+ and PUREX processes. Based on the experience gained through this effort, engineers will have the information necessary to decide if these technologies should be advanced to the prototype stage and tested at the pilot plant level. Through the experimental work planned as part of this effort, researchers will also develop a better understanding of the chemical interactions of the actinide elements, providing …

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

Separations Campaign (TRP)

The stability of the association of iodine with FCC and NOM products were studied. Product distributions for the various matrices under various reaction conditions were examined in order to maximize the binding of iodine. The recovery of the iodine from the sequestration matrices was also examined, along with the conversion of the iodine to matrices more suitable for geological storage and/or use as transmutation targets.

The following are the specific research objectives and goals:

• Develop bench-scale experimental set-up and procedures for simulating plutonium extraction process (PUREX) head-end vapor phase.
• Develop experimental procedures for evaluating iodine sequestering methods using bench-scale procedures. …