Physical Sciences and Mathematics Commons^™

Photochemical Reactions Of Optically Active Chiral And Achiral Organic Materials, Nicie Conley Murphy

Doctoral Dissertations

Sodium chlorate, NaClO₃, which crystallizes in the space group P2₁3, forms optically active crystals upon crystallization although the molecule itself is achiral. NaClO₃, has been shown to produce an asymmetric distribution of (+) and (-) crystals when crystallized from water while stirring. It has been discovered that beta or positron radiation can also induce asymmetric crystallization in NaClO₃ solutions. Like NaClO₃, achiral 4,4’-dimethylchalcone crystallizes in enantiomeric forms in the space group P2₁3. Kondepudi et al. provided evidence that stirred crystallizations of 4,4’-dimethylchalcone can induce a bimodal distribution of …

Study Of The N = 77 Isotones Near The Proton-Drip Line; Isomeric Decays Of 140Eu, 142Tb, 144Ho, And 146Tm, Mohammed Noor Tantawy

Doctoral Dissertations

In this dissertation, the systematics of the [pi]h₁₁/₂ [tensor] [nu]h₁₁/₂ and [pi]h₁₁/₂ [tensor] [nu]s₁/₂ isomeric configurations were studied for the odd-Z, N = 77 isotones near the proton drip line. The isomeric decays in ¹⁴⁰Eu, ¹⁴²Tb, ¹⁴⁴Ho and ¹⁴⁶Tm were measured by means of X-ray, [gamma]-ray and charged particle spectroscopy at the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). The spin and parity of I[pi] = 8⁺ and 5⁻ were deduced for the isomers in ¹⁴⁰ Eu and ¹⁴²Tb. New decay schemes were established, and the half-lives of the 8⁺ …

Gravity In Extra Dimensions Of Infinite Volume, Chad Aaron Middleton

Doctoral Dissertations

In this thesis, we discuss various aspects of the Dvali-Gabadadze-Porrati (DGP) model in D-dimensions. Firstly, we generalize the DGP model, which consists of a delta-function type 3-brane embedded in an infinite volume bulk-space by allowing the 3-brane to have a finite thickness. We calculate the graviton propagator in the harmonic gauge both inside and outside the brane and discuss its dependence on the thickness of the brane. We obtain two infinite towers of massive modes and tachyonic ghosts. In the thin-brane limit, we recover the four-dimensional Einstein gravity behavior of the graviton propagator which was found in the delta-function treatment. …

The Ds/Cft Correspondence And Quasinormal Modes Of Black Holes, Scott Henry Ness

Doctoral Dissertations

In this thesis we discuss two aspects of quantum gravity and break it up in the following way. In part I, we discuss a scalar field theory living in de Sitter space-time. We may describe the infinite past or future as being boundaries of this space-time and, on these boundaries we construct a field theory. It has been shown by Strominger that there exists a correspondence between the bulk de Sitter space-time and the field theory living in the infinite past [1]. This may be described as a holographic principle, where information in the bulk de Sitter space-time corresponds to …

Interdisciplinary Approaches To New Chemical Analysis, David Lynn Rodman

Doctoral Dissertations

The primary focus of this dissertation is the development of new chemical analyses for inorganic, organic, and organometallic compounds. Interdisciplinary approaches combining analytical, polymer, inorganic, organic, and materials chemistry have been used to develop new analytical methods. Topics discussed in this dissertation include the development of a sol-gel based metal ion sensor, photochemical oxidation of a biomimetic Cr(III) complex, photochemical oxidation of organic ligands and other interferences in model Pd catalyst complexes, modified Fujiwara reactions for the detection of halogenated hydrocarbons, and the development of a controlled-release polymer for delivery of reagents needed for chemical sensing applications.

High Performance Parallel Approximate Eigensolver For Real Symmetric Matrices, Yihua Bai

Doctoral Dissertations

In the first-principles calculation of electronic structures, one of the most timeconsuming tasks is that of computing the eigensystem of a large symmetric nonlinear eigenvalue problem. The standard approach is to use an iterative scheme involving the solution to a large symmetric linear eigenvalue problem in each iteration. In the early and intermediate iterations, significant gains in efficiency may result from solving the eigensystem to reduced accuracy. As the iteration nears convergence, the eigensystem can be computed to the required accuracy.
Traditional real symmetric eigensolvers compute the eigensystem in three steps: 1) reduce a dense matrix to a symmetric tridiagonal …

Structural And Spectroscopic Studies Of Transition Metal Organometallic And Coordination Complexes With Reference To Catalysis, Megan Taliaferro Bragg

Doctoral Dissertations

Inorganic chemistry encompasses a variety of topics and in many ways, these advances affect a wider sphere of chemists than purely inorganic and progress in this field is interesting to many scientists. The developments presented in this dissertation are significant as they affect three issues: catalytic reactivity, ligand fluxionality, and catalyst development. Catalysis affects industrial profit, pharmaceutical development, agrochemical synthesis, spectroscopy, enzymatic activity, and polymerization.

Progress in certain areas such as the [Cp*Rh(TsDPEN)] (TsDPEN = p-toluenesulfonyldiphenylethylenediamine) has lead to a moiety that is a powerful and efficient catalyst for the reduction of C=N bonds. The precise mechanism of the …

The Development Of Building Block Methodologies To Produce Nanostructured Heterogeneous Catalysts By Design, Jason Curtis Clark

Doctoral Dissertations

Building block methods were successfully developed to demonstrate the potential of this approach to synthesizing nanostructured heterogeneous catalysts by design. The octa(trimethyltin) cuboctameric spherosilicate, Si₈O₂₀(SnMe₃)₈, was used as the building block for the synthesis of these materials. The solid state structure of this building block was characterized and compared to other solid state structures of Si₈O₁₂ containing compounds. These studies showed that this building block is composed of rigid tetrahedral units connect through a flexible siloxy bridge. The trimethyltin functionality present on this molecular precursor will react with metal …

Ac Loss And Thickness Dependence Of Critical Currents In Coated Conductors, Anota Oluwatoyin Ijaduola

Doctoral Dissertations

This program of research is directed toward understanding the physical properties of certain materials in superconductive “coated conductors.” Specifically investigated were Ni1−xWx alloys for use as substrate and thin films of YBa 2Cu3O7, a high- Tc superconductor with many attractive features. A study has been conducted on the magnetic properties of a series of biaxially textured Ni1−xWx materials with compositions x = 0, 3, 5, 6, and 9 at.% W. These materials are important as substrates for “RABiTS”-type coated conductors that incorporate high temperature superconductors for current transport. The quasi-static dc and ac …

Photo-Acoustic Analysis Of Dental Materials And Tissue, Pavlina Jetchkova Jeleva

Doctoral Dissertations

The goal of the presented study is the investigation of the feasibility of using optically generated acoustic waves for analysis of dental material below laser-ablation threshold.

The temperature rise of dental material and tissue has been modeled analytically and numerically, and measured experimentally. Following interactions with nano- and femto-second laser radiation the temperature rises at a rate of typically 1 ±C per J=cm2, along with the generation of an acoustical wave. The results from the models agree with the experiment. The acoustic measurements show differences in the acoustic signal strength and the frequency spectrum when the canal in the …

Unsaturated Flow And Transport Of 90Sr, Co(Ii)Edta, And U(Vi) In Undisturbed Cores From The Hanford Formation, Hanford, Wa, Mary Fairfax Nichols-Pace

Doctoral Dissertations

At the U.S. Department of Energy’s Hanford Site in Richland, WA nuclear processing wastes, such as Sr-90, organic chelating agents such as EDTA, Co-60, and U(VI) have been detected in the vadose zone beneath the underground storage tanks. There is concern that waste released to the vadose zone could reach the groundwater and eventually flow into the Columbia River. The goal of this paper is to provide an improved understanding of coupled hydrologic and geochemical mechanisms that influence contaminant transport in the Handford vadose zone. Disturbed sediment and undisturbed sediment cores were collected from the Environmental Restoration Disposal Facility (ERDF) …

Parity Theorems For Combinatorial Statistics, Mark A. Shattuck

Doctoral Dissertations

A q-generalization Gn(q) of a combinatorial sequence Gn which reduces to that sequence when q = 1 is obtained by q-counting a statistic defined on a sequence of finite discrete structures enumerated by Gn. In what follows, we evaluate Gn(−1) for statistics on several classes of discrete structures, giving both algebraic and combinatorial proofs. For the latter, we define appropriate sign-reversing involutions on the associated structures. We shall call the actual algebraic result of such an evaluation at q = −1 a parity theorem (for the …

Microcapsule Biosensors Based On Competitive Binding And Fluorescence Resonance Energy Transfer Assays, Swetha Chinnayelka

Doctoral Dissertations

Fluorescent sensing systems offer the potential for minimally invasive monitoring with implantable devices, but they require carrier technologies that provide suitable immobilization, accessibility, and biocompatibility while maintaining adequate response characteristics. Towards the development of this goal, a general design of a biosensor with the capability of detecting different metabolites was investigated. The approach is based on the encapsulation of a competitive binding assay in microcapsules and monitoring the changes in fluorescence resonance energy transfer (FRET) in the presence of analyte. To experimentally demonstrate this type of sensing system, glucose was chosen as the model target analyte. The design, fabrication, and …

Availability Modeling And Evaluation On High Performance Cluster Computing Systems, Hertong Song

Doctoral Dissertations

Cluster computing has been attracting more and more attention from both the industrial and the academic world for its enormous computing power, cost effective, and scalability. Beowulf type cluster, for example, is a typical High Performance Computing (HPC) cluster system. Availability, as a key attribute of the system, needs to be considered at the system design stage and monitored at mission time. Moreover, system monitoring is a must to help identify the defects and ensure the system's availability requirement.

In this study, novel solutions which provide availability modeling, model evaluation, and data analysis as a single framework have been investigated. …

Studies Directed Toward The Synthesis Of Acylated Phloroglucinols, Joseph Allen Burlison

Doctoral Dissertations

The synthesis and application of α-allenyl ketones directed toward the synthesis of polycyclic polyprenylated acylphloroglucinols are described. A functionalized α-allenyl ketone was synthesized in twelve steps starting from 2-methyl-2-cyclohexenome in 24% overall yield. The α’ stereocenter in the α-allenyl ketone was stereoselectively quaternized using a Tsuji allylation, Mukaiyama adol condensation sequence to afford C-1 functionalized allenyl cyclohexanone building blocks. A survey of acetals and reaction conditions for the Mukaiyama reaction suggested that 3-tert-butyldiphenylsiloxypropanal dimethyl acetal could be used, and indeed this reagent in the presence of TiCl₄∙Ti[OCH(CH₃)₂]₄ gave the aldol product …

Factors Affecting The Phase Separation Of Liquid Crystals From Acrylate-Based Polymer Matrices, Nathan Joseph Crawford

Doctoral Dissertations

The work presented in this dissertation covers the study of phase separation of small-molecule liquid crystals (LC's) from acrylate-based polymer matrices. These materials are used in the construction of polymer dispersed liquid crystals, or PDLC's, an emerging technology with applications ranging from privacy windows to photonic materials.

The first part of this study involves the determination of the effect of increasing polymer molecular weight on the solubility of the LC 4' -octyl-4-biphenyl carbonitrile, or 8CB, in poly(methyl methacrylate), or PMMA. Optical microscopy is used to determine the equilibrium phase diagrams for blends of 8CB and PMMA with weight-average polymer molecular …

Lanthanide Separation Using Rate-Controlled Solvent Extraction, Joey Edwin Dickson

Doctoral Dissertations

Solvent extractions of many of the lanthanide ions in both single ion and mixed ion environments have been carried out. These cations were first complexed with an aqueous complexing agent and were extracted with DEHPA (di-2 ethylhexylphosphoric acid) in an organic phase (kerosene). The experiments were designed to measure the rates of extraction in the hope that separation factors might be enhanced under non-equilibrium conditions. The complexing agents tried include ethylenediaminetetraacetic acid (EDTA), tetraethylenepentamine (tetraen), nitrilotriacetic acid (NTA), and diethylenetriamine (dien). These represent a hexadentate, pentadentate, tetradentate, and tridentate agent respectively. EDTA was determined to give the best results for …

C3/C4 Variations In High Salt Marsh Sediments: An Application Of Compound Specific Isotopic Analysis Of Lipid Biomarkers To Late Holocene Paleoclimatic Research, Benjamin Ryan Tanner

Doctoral Dissertations

Chapter 1

Bulk carbon isotopes were previously used as a tool to differentiate between C3 and C4 plant communities in ancient salt-marsh deposits (Chmura and Aharon 1995). However, the bulk carbon values reflect organic matter contributions not only from salt-marsh plants, but also from algal bacterial inputs, as well as allochtonous terrestrial organic matter. The introduction of gas chromatography-isotope ratio mass spectrometery (GC-IRMS) allows for the separation of algal vs. higher plant contributions to the sediment pool. In the present study, this technique is applied to a core and modern plant samples collected from two Maine salt-marshes. We sampled 10 …

Shell Model Monte Carlo Method In The Pn-Formalism, Cem Ozen

Doctoral Dissertations

We report on the development of a new shell-model Monte Carlo algorithm, which uses the proton-neutron formalism. Shell model Monte Carlo methods, within the isospin formulation, have been successfully used in large-scale shell-model calculations. Motivation for this work is to extend the feasibility of these methods to shell model studies involving non-identical proton and neutron valence spaces. We show the viability of the new approach with some test results. Finally, we use a realistic effective nucleon-nucleon interaction in the model space described by (1p_1/2, 0g_9/2) proton and (1d_5/2, 2s_{1/2 …}

Synthesis And Applications Of Monolithic Hplc Columns, Chengdu Liang

Doctoral Dissertations

Silica and carbon monolithic columns were synthesized and modified for liquid chromatography applications. Column configurations and cladding techniques were investigated in detail. Three novel approaches have been developed for the synthesis of bimodal porous rods. Out of these three methods, gel-casting was adopted for the synthesis of silica monoliths with ordered mesopores and uniform macropores; the use of colloidal templates and dual phase separation has been successfully implemented for the synthesis of carbon monoliths with well-controlled meso- and macro- porosities. The formation of mesopores in carbon materials has been further studied in the microphase separation of block copolymers. Electrochemical modification …

Tungsten Alkyl Alkylidyne And Bis(Alkylidene) Complexes. Their Unusual Inter-Conversion And Reactions With Phosphines, Dioxygen And Water, Laurel Anne Morton

Doctoral Dissertations

This dissertation focuses on the unique chemistry of d0 alkylidyne and bis (alkylidene) complexes with β-silicon atoms. The goals of this dissertation research were to prepare and characterize these new d0 transition metal complexes, to study their reactivities including thermodynamics and kinetics of the inter-conversion between the alkylidyne and bis(alkylidene) complexes, and to explore the mechanism of the reactions of O2 or water with d0 alkylidyne complexes.

A summary of the research in this dissertation is provided in Chapter 1.Chapter 2 reports the study of an unusual exchange between new alkyl alkylidyne and bis(alkylidene) complexes …

A Tree-Ring Oxygen Isotope Record Of Tropical Cyclone Activity, Moisture Stress, And Long-Term Climate Oscillations For The Southeastern U.S., Dana Lynette Miller

Doctoral Dissertations

Geological proxies are needed to extend the record of hurricane occurrence beyond historical observations. Tree rings preserve uniquely high resolution and precisely dated records of past environmental conditions. Oxygen isotopic compositions of alpha cellulose in seasonally-resolved components (earlywood (EW) and latewood (LW)) of tree rings of southeastern coastal plain pines predominantly reflect precipitation source and/or temperature providing a snapshot of climate activity for the region.

Tropical cyclones produce large amounts of precipitation with distinctly lower oxygen isotope ratios than typical low-latitude thunderstorms. Evidence of isotopically depleted precipitation may persist in surface and soil waters for several weeks after a large …

Geochemical Investigations Of Ordinary Chondrites, Shergottites, And Hawaiian Basalts, Valerie Slater Reynolds

Doctoral Dissertations

Part I: Quantifying peak temperatures achieved during metamorphism is critical for understanding the thermal histories of ordinary chondrite parent asteroids. I performed two-pyroxene geothermometry, using QUILF95, on the same Type 6 chondrites for which peak temperatures were estimated using the plagioclase geothermometer. Pyroxenes record a narrow, overlapping range of temperatures in H6 (865-926°C), L6 (812-934°C), and LL6 (874-945°C) chondrites. Lower plagioclase temperature estimates may not reflect peak metamorphic temperatures because chondrule glass probably recrystallized to plagioclase prior to reaching the metamorphic peak. The average temperature for H, L, and LL chondrites (~900°C) is at least 50°C lower than peak temperatures …

Analysis Of Martian Parental Melts And Thermal Infrared Studies Of Putative Paleolake Basins On Mars, Karen Renée Stockstill

Doctoral Dissertations

Both martian meteorites and remote sensing data allow us to study the geologic history of Mars. Martian meteorites can reveal information regarding partial melting of the Mars mantle and the surface processes that affected the meteorite following eruption (weathering, impact ejection, etc.). Remote sensing data can be used to investigate the local-, regional- or global-scale surface of Mars in terms of composition and geomorphology. A well-rounded approach is necessary to address fundamental questions regarding the geologic history of Mars.

We studied melt inclusions in augite of the martian meteorite Nakhla to better understand the magma that produced this rock. This …

The Middle Ordovician Tellico-Sevier Syncline: A Stratigraphic, Structural And Paleoseimic Investigation., Stephen Christopher Whisner

Doctoral Dissertations

Analyses of remote-sensing satellite data, aerial photography, radar images, and digital elevation models, and detailed (1:24,000-scale) geologic mapping of bedrock and surficial deposits were conducted in a portion of the southeastern Tennessee. This area contains the southern portion of the Tellico-Sevier Alleghanian syncline and the highest concentration of modern earthquakes as well as two major rivers with unconsolidated floodplain and terrace deposits that would be most susceptible to disruption by earthquakes. Cambrian to Mississippian age rocks occurs in the syncline. The majority of detailed mapping was conducted in Middle Ordovician Chickamauga Group rocks.

Earthquakes occur in the East Tennessee seismic …

Synthesis Of A C-Linked Methyl Β-Disaccharide As A Building Block Of Hyaluronic Acid Oligosaccharide Mimetics, Kpakpo Ambroise Akue

Doctoral Dissertations

Hyaluronic acid is a viscous high MW polysaccharide that is synthesized in the plasma membrane. It is found in the connective tissue space, in the synovial fluid of movable joints and in the vitreous humor of the eye. Its chemical structure is composed of a repeating disaccharide unit in which D-glucuronic acid is linked to the 3-position of N-acetyl-D-glucosamine. It appears to play an important role in the metastasis of cancer cells since cancer cell’s CD44 receptors adhere to it and migrate to host cells. Our goal was to synthesize small HA-oligosaccharides that would behave as CD44 metastasis receptor antagonists. …

Understanding And Controlling The Molecular Level Processes Involved In The Development Of Latent Fingerprints Using The Cyanoacrylate Fuming Method, Stephen Paul Wargacki

Doctoral Dissertations

The cyanoacrylate fuming method (CFM) is the standard method for forensic investigators to develop latent fingerprints from nonporous substrates. Variations in the effectiveness of the technique and the quality of the ethylcyanoacrylate (ECA) polymer impression formed during the development process have lead researchers to investigate the fundamental reactions between the print residue and the developing vapor. Identification of the active initiating species in the residue is an essential first step to understanding the development process. The fingerprint residue is composed primarily of water and eccrine salts, of which, water is generally accepted as the active initiator. However, initiation by water …

Sedimentation, Hydrology, And Bottomland Hardwood Forest Succession In Altered And Unaltered Tributaries Of The Hatchie River, Tn, Aaron R. Pierce

Doctoral Dissertations

Hydrologic and sedimentation processes are critical in determining floodplain site conditions and the distribution of bottomland hardwood (BLH) forest communities (Hodges 1997). Channelization of streams associated with BLH wetlands has occurred extensively throughout the southeastern United States, altering the hydrologic and sedimentation processes that sustain these systems. In western Tennessee, channelization and past land-use practices have resulted in drastic geomorphic and hydrologic changes including excessive sand deposition on floodplains, and in extreme cases, the formation of valley plugs and shoals.

Our understanding of the processes associated with valley plugs and shoals, their rates and variability, and their impacts on BLH …

Hypersurfaces Of Prescribed Curvature In Hyperbolic Space, Marek Szapiel

Doctoral Dissertations

In this paper we consider the problem of existence of hypersurfaces with prescribed curvature in hyperbolic space. We use the upper half-space model of hyperbolic space. The hypersurfaces we consider are given as graphs of positive functions on some domain Ω ∈ Rⁿ satisfying equations of form

f (A) = f (κ₁, . . . , κ_n) = ψ,

where A is the second fundamental form of a hypersurface, f (A) is a smooth sym- metric function of the eigenvalues of A and ψ is a function of position. If we impose certain conditions …

Improvement Of Long Range Order In Diblock Copolymer Templates For Nanostructure Deposition, Scott Michael Fontana

Doctoral Dissertations

This dissertation presents work that examines the use of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer thin films as nanoporous templates. Diblock copolymer thin films are able to microphase separate to produce microdomains on the nanometer length scale. Cylindrical domains can be perpendicularly oriented when cast as a thin film on a neutral surface. From the perpendicularly oriented cylindrical microdomains, nanoporous templates can be created.

Cylindrical domain block copolymer templates can lead to the production of nanostructures, but the lack of long range ordering prevents the use of diblock copolymer template for some industrial applications. Graphoepitaxy utilizes a …