Physical Sciences and Mathematics Commons^™

Physical Adsorption Of Ethylene On Mgo(100): Effects Of Substrate Ionicity And Symmetry On Wetting, Andi Barbour

Doctoral Dissertations

The wetting behavior of ethylene adsorbed on MgO(100) was investigated from 83{ 135 K using high resolution volumetric adsorption isotherms. Layering transitions for ethylene on MgO(100) are observed below the bulk triple point at 79.2 K and 98.4 K, respectively. From these isotherms, thermodynamic quantities associated with physical adsorption are determined. It was found that the average area occupied by ethylene on MgO(100) is around 22.6 squared angstroms per molecule. Using the two dimensional isothermal compressibility, the location of two potential phase transitions are identified at 108.6 K and 116.5 K for the first and second layer, respectively. The potential …

Studies Of Tungsten Alkyl Alkylidyne Compounds And Iron Porphyrin Derivatives, Brenda Ann Dougan

Doctoral Dissertations

This dissertation focuses on two research projects. The first project examines the reactions of tungsten(VI) alkyl alkylidyne and bis-alkylidene complexes with phosphines and water and the studies of thermodynamics and kinetics of the reactions. These studies have been conducted in part to determine the mechanistic pathway in the formation of novel tungsten(VI) species. The second portion of this dissertation focuses on the spin density and structures of biomimetic Fe(III) porphyrin derivatives using neutron and X-ray diffraction techniques. The spin density and magnetic properties of an Fe(III) porphyrin derivative has been determined by polarized neutron diffraction.

In the first portion of …

The Design And Synthesis Of Biotinylated Tylophorine Analogues For Use As Affinity Probes In The Elucidation Of The Cellular Targets Of Dcb-3503, Samson Francis

Doctoral Dissertations

The tylophorine analogue, DCB-3503 (1-62b, NSC-716802), has been found to exhibit broad spectrum activity in vitro in the National Cancer Institute’s (NCI) panel of 60 human-derived cell lines. Recent studies involving HepG2, a human hepatocellular carcinoma cell line, and two pancreatic ductal carcinoma cell lines (PANC-1 and HPAC), have suggested that DCB-3503 (1-62b) exerts its unique growth inhibition properties by modulating nuclear factor kappa B activity as well as through the inhibition of nuclear protein synthesis. However, the physiologically relevant protein binding partner(s) of DCB-3503 (1-62b) have not been identified. Herein, the design and …

Synthesis And Characterization Of Branched Polyelectrolytes: Star-Branched Napss, Daniel W. Holley

Doctoral Dissertations

In this thesis, we examined the effect of branching on the solution characteristics of polyelectrolytes using a set of star-branched NaPSS. The polystyrene precursors to these polyelectrolytes were synthesized using anionic polymerization allowing for the production of three distinct groups of star-branched polystyrenes with varying functionality and arm length.

Following sulfonation, several methods commonly employed in the literature for evaluation of sulfonation degree we established that sulfonation was quantitative. TGA was also demonstrated to reveal important characteristics of the sample.

We used aqueous SEC coupled with a multiple angle light scattering detector to determine several molecular characteristics of the star-branched …

Design And Synthesis Of Novel Tylophorine Analogs And Their Biological Activity, Julio Gutierrez

Doctoral Dissertations

Alkaloids containing the nitrogen atom in the bridgehead position of two rings, such as indolizidine, pyrrolizidine, and quinolizidine alkaloids, have a wide and varied distribution in nature. Some of these alkaloids demonstrate a broad range of pharmacological activities and have generated substantial synthetic interest. This thesis covers the total synthesis of novel tylophorine analogs called DCB 3503, DCB 3506, DCB 3507, DCB 3508, DCB 3509, and a derivative with a biotinylated chain attached to DCB 3506 for use as a biological probe. This thesis discusses the biological activity of these compounds as well.

Computational Exploration Of The Interaction Of Molecular Hydrogen With An Anionic Hydrogen Atom, Patrick Karl Moehlen

Doctoral Dissertations

The focus of this dissertation is to facilitate the computation of the infrared absorption line shape of solid para-hydrogen with an anionic hydrogen atom dopant. For this, we compute the complete potential energy surface for the interaction of H¯ with H². The coupled cluster with singles, doubles, and perturbative treatment of triple excitations method was used with augmented correlationconsistent polarized valence triple-zeta atom-centered basis sets and a set of bonding functions.

The focus then turns to describing the rovibrational Hamiltonian of the system with the coupledchannel method. We find bound and quasi-bound stationary states of the system for …

Spectroscopic Imaging For The Detection And Identification Of Bacterial Contaminations, Michael Gilbert

Doctoral Dissertations

There exist many types of harmful bacteria that can contaminate foods and cause serious illness, which often have their own best courses of treatment. This requires the classification of different types of bacteria. Traditional methods of bacterial identification, while able to provide accurate classification, are often very time-consuming processes. In the case of a potentially fatal bacterial infection, time is often of the essence. FTIR spectroscopy is a faster, more practical alternative that can discriminate different strains of bacteria, based on their spectral signatures, with high confidence.

Bacterial contaminations on food exist as small, localized colonies that must be found …

A Theoretical Study Of Methanol Oxidation Mechanisms By Methanol Dehydrogenase Enzymes For Fuel Cell Applications, Nagesh B. Idupulapati

Doctoral Dissertations

Enzymes are considered for electrochemical generation of power in fuel cells. Methanol dehydrogenase (MDH) is one such enzyme, which has been used as an anodic catalyst for a methanol-fed biofuel cell producing enough power for small electronic device applications. In practice, however, there are power output limitations associated with this MDH fuel cell, which may potentially be eliminated or reduced if the reactivity of this enzyme during the oxidation of methanol at the molecular level is clearly understood.

Two mechanisms for the methanol oxidation process by MDH have been proposed in the literature, Addition-Elimination (A-E) and Hydride Transfer (H-T), but …

Computational Study Of Pristine And Titanium-Doped Sodium Alanates For Hydrogen Storage Applications, Gopi Krishna Phani Dathar

Doctoral Dissertations

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained …

Chasing Μ, Joseph P. Cannon

Doctoral Dissertations

Conducting and semiconducting, π-conjugated polymers are promising materials for micro- and nano-optoelectronic applications because of their widely tunable physical, electrical, and optical properties. These polymers have been used to fabricate a number of electronic devices including field-effect transistors, light-emitting diodes, and photovoltaic cells. However, widespread commercial application of these devices has yet to be realized, due in part to poor electronic transport characteristics and device degradation.

Nanostructuring of conjugated polymers by various methods has demonstrated marked improvements in molecular ordering and electronic transport. In this research, nanoscale, tubular structures of semiconducting polymers fabricated by template wetting nanofabrication procedures are explored. …

Electrodeposition Of Inorganic Materials With Tailored Shapes And Chiral Morphologies, Elizabeth A. Kulp

Doctoral Dissertations

"This dissertation investigates the electrodeposition of metal oxide films and biomaterial deposits on polycrystalline and single crystal substrates. Paper I describes the mechanisms and the characterization of an electrodeposited polycrystalline insulator, ceria (CeO₂), on Hastelloy substrates produced by the electrochemical oxidation of Ce(III) acetate complexes. In Paper II, epitaxial films of magnetite (Fe₃O₄) and ferrihydrite (Fe₁₀O₁₄(OH)₂) are deposited on gold single crystals. Paper III reports the electrodeposition of epitaxial Fe₃O₄ and zinc ferrite (ZnFe₂O₄) periodic nanostructures known as superlattices by pulsing between two potentials. Papers IV and V describe chiral electrodeposition. In Paper IV, epitaxial, chiral orientations of cupric oxide …

Investigation Of The Interactions Between Selected Nanoparticles And Human Lung Carcinoma Cells At The Single Cell And Single Particle Level, Isaac Stayton

Doctoral Dissertations

"The recent advances in nanomaterials development and applications have sparked concerns regarding the safety of these materials in living organisms. This body of work investigates specific interactions between chosen nanoparticles and living human lung carcinoma (A549) cells"--Abstract, page iv.

A Study Of The Beneficial Role Of Thiol Antioxidant Supplementation In Various Forms Of Glutathione Deficiency, Linu Sara Abraham

Doctoral Dissertations

"Oxidative stress plays a major role in the pathology of numerous disorders afflicting humans, ranging from neurodegenerative diseases, to cancer, and heavy metal toxicity. Scientists are on the constant lookout for new and better antioxidants that have the ability to slow, if not stop the harmful degenerative effects of free radicals in oxidative stress related disorders. Both synthetic and naturally occurring compounds are being constantly screened for their antioxidant properties. This study attempted to evaluate the abilities of a thiol antioxidant, N-Acetylcysteine amide (NACA), to protect cells from the harmful effects of glutathione depletion in two different models of oxidative …

F₂-Isoprostanes Study After Exposure To Selected Nanoparticles By Liquid Chromatography/Tandem Mass Spectrometry And Investigation Of Nanoparticles On The Cytotoxicity Effect Of Arsenic In Vitro, Xiaoqian Liu

Doctoral Dissertations

"Nanopartices as a new class of materials found their applications in industry, aerospace, clinical diagnosis and cancer therapy. Recently, the health effects of nanoparticles have caused people great concerns. This dissertation studies the mechanisms of nanoparticle cytotoxicity in human lung epithelial cells (A549). F₂-isoprostanes are novel reliable biomarkers for lipid peroxidation. In the first part of this work, total free F₂-isoprostanes were quantified by high performance liquid chromatography/mass spectrometry followed by the exposure of SiO₂ (15 nm), CeO₂ (20 nm), Fe₂O₃ (30 nm), and ZnO (70 nm) nanoparticles for 24 hours. For the first time, the results showed that F₂-isoprostanes …