Physical Sciences and Mathematics Commons^™

Preparation, Characterization And Reactivities Of Early Transition Metal Silyl Compounds, He Qiu

Doctoral Dissertations

This dissertation focuses on syntheses, characterization and reactivities of Groups 4 and 5 metal amide silyl complexes free of anionic π-ligands.

A summary of the research in this dissertation is provided in Chapter 1. Chapter 2 reports an unusual reaction between Ta(NMe₂)₄SiBu^tPh₂ (1) and O₂. Three products (Me₂N)₄Ta(OSiBu^tPh₂) (2), (Me₂N)₃Ta(ONMe₂)(OSiBu^tPh₂) (3) and (Me₂N)₂(Ph₂Bu^tSiO)₂(Me₂NCH₂NMe)₂Ta₂(μ …

Static And Dynamic Magnetism In The Electron-Doped High-Temperature Superconductor Pr0.88Lace0.12Cuo4-Δ And In The F-Electron, Non-Fermi Liquid Alloy Sc1-XUXPd3, Stephen Dennis Wilson

Doctoral Dissertations

Here we present detailed studies of the spin dynamics within the electron-doped high temperature superconductor Pr_.88LaCe_.12CuO_4-δ (PLCCO) and within the non-Fermi liquid metal Sc_1-xU_xPd₃ (ScUPd). Comprehensive neutron scattering experiments were carried out mapping the evolution of magnetism within these systems as they are tuned across their respective phase diagrams. The novel features of the magnetic spectra within these systems are correlated with known anomalies in their quasiparticle behaviors driven through either the appearance of a superconducting phase in PLCCO or the emergence of a non-Fermi liquid phase in ScUPd.

For …

Innovative Methods Of Biomedical Molecular Analysis: Capillary Electrophoretic Study Of Amyloid Beta Conformations And Magnetically Assisted Transport Evanescent Field Fluoro-Assays, Amber D. Wellman

Doctoral Dissertations

Though the study of the human proteome (proteomics) is far more complicated than that of the genome, it may prove to be the next step toward gaining insight into the operation of biological systems. Understanding the role proteins and peptides play in disease, whether that be by their structure, expression or function, could lead to the identification of disease biomarkers for diagnosis or engender possibilities for treatment. To this end, the work discussed herein delves into the capillary electrophoretic (CE) analysis of amyloid beta conformations involved in abnormal aggregation and the creation and optimization of a novel bioassay method. By …

Structure And Transport Properties Of Epitaxial Oxide Thin Films: From Synthesis To Characterization, Junsoo Shin

Doctoral Dissertations

Epitaxial thin films and heterostructures based on perovskite oxides have attracted significant attention in physics since perovskites exhibit an enormous range of electrical, magnetic, and optical properties, making them exciting systems for studies of the fundamental physical mechanisms of interactions between electron, lattice, and spin degrees of freedom. This dissertation has been focused on ferroelectricity in lowdimensional ferroelectric materials using ultra-thin ferroelectric epitaxial films (BaTiO₃) with a metallic electrode (SrRuO₃) by studying polarized ordering of the crystal structure and electronic transport through the films. High quality and highly oxidized epitaxial films are a prerequisite for the …

Evaluation Of Forest Management To Improve Breeding Habitat For Songbirds In Oak-Hickory Forests At Tennessee National Wildlife Refuge, Benjamin Stephen Thatcher

Doctoral Dissertations

Partners in Flight (PIF) recommends using silviculture to improve breeding habitat conditions for migrant landbirds. Alternative thinning treatments may benefit priority landbird species by increasing structural complexity in second-growth forests. However, the effects of thinning on landbird populations in oak (Quercus spp.)-hickory (Carya spp.) forests have not been experimentally demonstrated. I used a randomized and replicated large-scale manipulative experiment to evaluate the effects of thinning (i.e., crown-release and gap creation) on forest habitat characteristics and avian populations at the Tennessee National Wildlife Refuge. I collected data during 2001 (pre-treatment) and from 2002 to 2005 (1 to 4 years …

Leaf: A Learning-Based Fault Diagnostic System For Multi-Robot Teams, Balajee Kannan

Doctoral Dissertations

The failure-prone complex operating environment of a standard multi-robot application dictates some amount of fault-tolerance to be incorporated into every system. In fact, the quality of the incorporated fault-tolerance has a direct impact on the overall performance of the system. Despite the extensive work being done in the field of multi-robot systems, there does not exist a general methodology for fault diagnosis and recovery. The objective of this research, in part, is to provide an adaptive approach that enables the robot team to autonomously detect and compensate for the wide variety of faults that could be experienced. The key feature …

Surface Plasmon Enhanced Heating Of Gold Nanoparticles: A Plasmonic Optical Switch, Philip Gareth Evans

Doctoral Dissertations

Recent work by Lereu et al. (Appl. Phys. Lett. Vol. 86, 154101, 2005) demonstrates a method of all-optical transfer of modulation signals using surface plasmon excitation on thin gold films. Localized heating of the film, resulting from surface plasmon decay, alter the optical properties of the device. A similar optical modulation method is now presented using gold nanoparticles. Computational models are used to generate realistic values of the thermo-optical response of gold and the thermal dynamics of a hot nanoparticle-substrate device. Differential pump-probe reflectivity measurements were perferomed and demonstrate modulation frequencies of upto 10kHz, an improvement of two orders of …

Synthesis And Characterization Of Atomically Dispersed, Vanadosilicate Catalysts In Si8o20-Based Building Block Solids, Ming-Yung Lee

Doctoral Dissertations

Silica supported vanadium complexes have attracted interest as catalysts for a variety of catalytic reactions in the past two decades. Although many strategies have been developed for incorporating vanadyl species on silica surfaces, controlling dispersion and loading while simultaneously producing single site catalysts remains a challenging goal in this context and in catalysis as well.

A simple strategy for producing single-site and site-isolated vanadyl species has been explored which allows for control of both the connectivity to the support as well as the local surface structure around a V=O group. The main elements of this strategy involve construction of the …

Automated Gene Classification Using Nonnegative Matrix Factorization On Biomedical Literature, Kevin Erich Heinrich

Doctoral Dissertations

Understanding functional gene relationships is a challenging problem for biological applications. High-throughput technologies such as DNA microarrays have inundated biologists with a wealth of information, however, processing that information remains problematic. To help with this problem, researchers have begun applying text mining techniques to the biological literature. This work extends previous work based on Latent Semantic Indexing (LSI) by examining Nonnegative Matrix Factorization (NMF). Whereas LSI incorporates the singular value decomposition (SVD) to approximate data in a dense, mixed-sign space, NMF produces a parts-based factorization that is directly interpretable. This space can, in theory, be used to augment existing ontologies …

Reliability -Aware Optimal Checkpoint /Restart Model In High Performance Computing, Yudan Liu

Doctoral Dissertations

Computational power demand for large challenging problems has increasingly driven the physical size of High Performance Computing (HPC) systems. As the system gets larger, it requires more and more components (processor, memory, disk, switch, power supply and so on). Thus, challenges arise in handling reliability of such large-scale systems. In order to minimize the performance loss due to unexpected failures, fault tolerant mechanisms are vital to sustain computational power in such environment. Checkpoint/restart is a common fault tolerant technique which has been widely applied in the single computer system. However, checkpointing in a large-scale HPC environment is much more challenging …

Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony

Doctoral Dissertations

"Ethanol and ionizing radiation exposure are independently known to cause tissue damage through various mechanisms. Non-enzymatic and enzymatic metabolism of ethanol, the latter via the cytochrome P₄₅₀2E1-dependent pathway, produces free radicals which deplete cellular glutathione (GSH). Ionizing radiation exposure has been shown to induce lipid peroxidation, DNA damage, protein oxidation, and GSH depletion, as well. It was postulated that initial exposure to ethanol, followed by ionizing radiation, would result in heightened oxidative stress. The in vitro model used in this investigation was HepG2 cells (human hepatocellular liver carcinoma cell line), while the in vivo model was Cd-1 mice"--Abstract, page iii.

Incipient Continental Rifting: Insights From The Okavango Rift Zone, Northwestern Botswana, Baraka D. Kinabo

Doctoral Dissertations

"In this dissertation aeromagnetic, gravity, and Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) data from the Okavango Rift Zone in northwest Botswana are used to map the distribution of rift and basement structures. The distribution of these structures provide useful insights into the early stages of continental rifting. The objectives of this study are (1) assessing the role of pre-existing structures on rift basin development, (2) characterizing the geometry of the nascent rift basins, (3) documenting fault growth and propagation patterns, and (4) investigating the border fault development"--Abstract, page iv.

Synthetic Methods For Biologically Relevant Organofluorine Compounds, Meher Perambuduru

Doctoral Dissertations

"This thesis describes novel synthetic methodologies for the synthesis of biologically relevant organofluorine compounds"--Abstract, page iii.

Hyphenated Hplc-Ms Technique For Analysis Of Compositional Monosaccharides Of Transgenic Corn Glycoprotein And Characterization Of Degradation Products Of Diazinon, Fonofos And Aldicarb In Various Oxidation Systems, Tongwen Wang

Doctoral Dissertations

"The studies of this dissertation are composed of two sections. The first one deals with the analysis of compositional monosaccharides of transgenic corn glycoproteins. The method used in this study involved derivatization of monosaccharides with two fluorophores followed by HPLC/fluorescence detection for quantitative studies, and by HPLC/SSI/MS for identification confirmation of individual monosaccharide...The second section investigates the degradation processes of several pesticides including diazinon, fonofos and aldicarb in various oxidation systems"--Abstract, page iv.

Quantum Dot Photolithography, Raghuveer Reddy Gadipalli

Doctoral Dissertations

"This dissertation presents a simple method for the photolithographic patterning of silica hydrogel monoliths and planar substrates with quantum dots and inorganic semiconductor nanoparticles. We developed a method for surface patterning and bulk (3D) patterning of silica hydrogel monoliths and surface patterning of planar substrates with CdS, CdSe, PbS and PbSe quantum dots using infrared light, ultraviolet light, X-rays, and multi-photon ionization radiation. Precursor combinations were prepared which can readily dissociate with IR, UV, X-rays, and multi-photon ionization radiation. Different capping agents were used for improving quantum dot size distribution. The luminescence quantum yield of the composites can be increased …

Modeling Core Generation And Transport Phenomena Of Microcapsules, Xiaoshuo Wu

Doctoral Dissertations

Microcapsules play an important role in chemical, biomedical, and medical research. Of importance is their potential use as bio-sensors, as microreactors, and for drug delivery. In this dissertation, Computational Fluid Dynamics methodology is used to model the generation of droplets or cores (using alginate and oil) and to determine from the model process parameters needed for generating cores of homogeneous size for the manufacturing of microcapsules. Also, material diffusion through a microcapsule for controlled release is modeled based on finite difference methodology. The model was applied to experimental data on dextran release from microcapsules in order to estimate the diffusion …

Electron Beam Characterization Of Carbon Nanostructures, Eric Samuel Mandell

Doctoral Dissertations

"Atom-thick carbon nanostructures represent a class of novel materials that are of interest to those studying carbon's role in fossil fuel, hydrogen storage, scaled-down electronics, and other nanotechnology. Electron microscope images of "edge-on" graphene sheets show linear image features due to the projected potential of the sheets. Here, intensity profiles along these linear features can measure the curvature of the sheet, as well as the shape of the sheet (i.e. hexagonal, triangular). Also, electron diffraction powder profiles calculated for triangular graphene sheet shapes show a broadening of the low frequency edge of diffraction rings, in comparison to those calculated for …

An Investigation Of Lead And Other Metal Contaminants In The Sediments Of Clearwater Lake, Missouri, Gary W. Krizanich

Doctoral Dissertations

"The purpose of this investigation is to characterize the spatial and temporal distribution and concentration of trace metals in sediments of Clearwater Lake. Understanding how trace metals are released to and transported in aquatic environments is important to the overall understanding of the impacts of mining on the natural environment. The main focus of this research will be on historic sedimentation within Clearwater Lake, which may act as a sink where mining related trace metals are stored. Because of their high preservation rates in basins, sediments can provide detailed chronostratigraphic histories of trace metal inputs in lakes. Sediment records can …

Impacts Of Acid Mine Drainage On Carbon Cycling In Receiving Streams, Ernest W. Fonyuy

Doctoral Dissertations

"Field and laboratory investigations of acid mine drainage (AMD) contaminated and uncontaminated waters were conducted in order to determine and model processes and reaction mechanisms that control dissolved inorganic carbon (DIC) transformation and shifts in isotope ratio of DIC (Δ¹³C_DIC). The results show that AMD caused variable pH changes, overall decreases in Fe²⁺, alkalinity, and DIC, and increases in (Δ¹³C_DIC) in receiving streams. AMD caused more than 50 to > 98% seasonal DIC loss in stream water through CO₂ degassing. High DIC losses corresponded to high Fe²⁺ and lower or no HCO₃⁻ in the water samples, because …

The Effects Of Fast Secondary Electrons On Low Voltage Electron Beam Lithography, Mehdi Bolorizadeh

Doctoral Dissertations

In 1981 Prof. Sir Alec Broers suggested that the spatial limit of direct writing electron beam lithography (DWEBL) would be limited to ~10 nm by the laterally scattered fast secondary electrons (FSE) even in atomically thin resist. Experiments and simulations have been carried out to quantify the contribution of FSE to the energy deposition that results in exposure of the resist over high beam energies. One possible solution to this restriction would be to use low energy electrons.

To examine Broers' hypothesis in low voltage electron beam lithography (EBL), studies in the low energy range on the effects of FSE …

Linear And Nonlinear Chiroptical Effects, Watheq Ahmad Al-Basheer

Doctoral Dissertations

Chiroptical effects of linear and nonlinear nature are investigated by employing a variety of spectroscopic methods, such as linear and nonlinear circular dichroism, optical rotation, vibrational Raman scattering, infrared absorption and Vibrational Circular Dichroism. (2+1) Resonance Enhanced Multiphoton Ionization Circular Dichroism (REMPICD) is a direct demonstration of the nonlinear chiroptical effects of a sample of R-(+)-3-methylcyclopentanone. Solvent effects on circular dichroism is studied for 35 common solvents, which is significantly attributed to the solute- solvent electrostatic and Van der waals interactions for CD and ORD of R3MCP. Hartree-Fock and Density Function Theoretical calculations of R3MCP CD and …

Combined Study Of Reactor And Terrestrial Antineutrinos With Kamland, Mikhail Batygov

Doctoral Dissertations

This dissertation presents a combined study of antineutrinos of terrestrial and reactor origin detected by Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND). Of special physical interest are neutrino oscillation parameters and the terrestrial antineutrino flux, the former being of a profound importance for new physics beyond the Standard Model, and the latter having significant implications for geophysics. The analysis described here uses a comprehensive likelihood model to naturally combine terrestrial and reactor antineutrino studies within a single framework. The use of this likelihood model and better event reconstruction tools allowed to obtain narrower limits for the oscillation parameters and the terrestrial …

Interference Effects Among J = 3/2+ Resonances In 19Ne System & Searching For Resonances In The Unbound 6Be Nucleus, Kyung Yuk Chae

Doctoral Dissertations

The ¹⁸F(p,α)¹⁵O reaction plays a crucial role in understanding γ-ray emission from novae. Because of the importance of understanding the ¹⁸F + p reactions, a number of studies of the A=19 isobars have been made using stable and exotic beams. The interference effects among J ^π = 3/2⁺ resonances in the ¹⁸F + p system, however, have never been measured, but they can change the S-factor by a factor of 20 at nova energies. R-matrix calculations indicate that the cross sections above the Ec.m. = 665 keV resonance are sensitive …

Single-Molecule Detection With Active Transport, David Allan Ball

Doctoral Dissertations

A glass capillary is used near the focal region of a custom-built confocal microscope to investigate the use of active transport for single-molecule detection in solution, with both one and two-photon laser excitation. The capillary tip has a diameter of several microns and is carefully aligned nearby to the sub-micron laser beam waist, collinear to the optical axis, so that a negative pressure-difference causes molecules to be drawn into the capillary, along the laser beam axis. The flow of solution, which is characterized by fluorescence correlation spectroscopy (FCS), can increase the single-molecule detection rate for slowly diffusing proteins by over …

Thermodynamic And Neutron Structural Studies Of Hydrocarbon Adsorption On Mgo Nanocubes, Richard E. Cook

Doctoral Dissertations

Presented is a series of thermodynamic and neutron scattering experiments used to probe the nature of the hydrocarbon - MgO (100) interaction. High-resolution volumetric isotherms are used to probe the wetting, layer transitions, heats of adsorption, two-dimensional compressibilities, and identify possible phase transitions of thin films of benzene, ethane, and n - pentane on MgO powders. Neutron diffraction experiments were used to probe the structure and identify any phase transitions within monolayer films of ethane, butane and n -pentane.

Benzene adsorption, while showing no visible layering steps, shows a shift in the shape of the isotherm for p/p_o > 0.7. …

Characterization Of Aβ Aggregates Using Hydrogen/Deuterium Exchange Mass Spectrometry, Maolian Chen

Doctoral Dissertations

The work presented in this dissertation aimed to localize the hydrogen-bonding interaction sites within Aβ aggregates associated with Alzheimer’s disease using hydrogen/deuterium exchange mass spectrometry (HDX-MS) coupled with proteolysis. Toward this end, an on-line digestion system utilizing a triaxial electrospray probe as the front end to MS was developed. Using this approach, regions of Aβ(1-40) fibrils and protofibrils that are protected from HDX have been identified. The HDX data show that the C-terminal segment 35-40 and the N-terminal segment 1-19 are highly exposed to exchange in both fibrils and protofibrils, while the internal fragment 20-34 is highly protected from exchange …

Management Of Requirements Changes In Sequence-Based Software Specifications, Lan Lin

Doctoral Dissertations

The sequence-based software specification method was developed to convert ordinary, or typical requirements and requirements statements into mathematically precise specifications, at an acceptable level of abstraction, for deterministic systems. In view of the iterative nature of modern software developing process, requirements, once defined, are not frozen; changes are integrated continuously that need to be accommodated and validated.

The need for managing changes of requirements in sequence-based specifications arises both as a consequence of practicing this method and as a general topic in software requirements engineering. In this research we have explored the theoretical consequences of three major requirements changes in …

The Reaction Of Telechelic Polymers At Multicomponent Interfaces: A Molecular Loop Study, James Kevin Rice

Doctoral Dissertations

The work presented in this dissertation attempts to form an understanding of the reaction parameters that govern the reaction of telechelic polymers to form multiply bound polymer chains, resulting in polymer loop formation, at both soft and hard polymeric interfaces. Both theoretical and experimental studies offer evidence that blocky copolymers, as opposed to random or alternating morphologies, are the best compatibilizers of a given polymer blend system. This has been attributed to the fact that blocky copolymers spread across the interface, with each block lying in or near the homopolymer region in which it is miscible, effectively “stitching” the interface …

Measurement Of The 32S(P,D)31S Reaction And Its Astrophysical Implications, Zhanwen Ma

Doctoral Dissertations

The ³⁰P(p,γ)³¹S reaction plays a crucial role in the synthesis of heavier nuclear species, from Si to Ca, in nova outbursts on ONe White Dwarfs [26, 28, 35]. However, its rate is very uncertain as a result of the lack of spectroscopic information on the levels above proton threshold in ³¹S. The currently adopted rate of this reaction, based on statistical Hauser-Feshbach calculations [36], could have an uncertainty as much as a factor of 100 higher or lower under nova conditions [26].

To reduce these uncertainties, we have measured differential cross sections for the ³²S(p,d) …

Multiple Approaches To The Separation Of Amino Acids And Biologically-Relevant Compounds, Lance Andrew Riddle

Doctoral Dissertations

The branch of analytical chemistry known as separations has continued to grow and expand ever since its beginnings a century ago. With all the technological advances occurring to make separations a more powerful technique, the main goal continues to be the desired separation of the compounds of interest in a mixture. Although a desired separation may be achieved, there can always be room for improvement with regards to the time necessary for the separation as well as better resolution of closely-related species as well as enantiomers of the same analyte.

In this work, a variety of separation methods and variations …