Physical Sciences and Mathematics Commons^™

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 …

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 …

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 …

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 …

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 …

Conservation Of Grassland Bird Populations On Military Installations In The Eastern United States With Special Emphasis On Fort Campbell Army Base, Kentucky, James J. Giocomo

Doctoral Dissertations

Grassland bird populations have decline significantly over the past 30 years because of the dramatic decrease of native grasslands through clearing of non-forested land for agriculture, and discontinued use of fire. It is imperative to understand the distribution and productivity of these birds and the potential for grassland management to enhance these declining populations, especially in land areas where the landuses may be compatible with grassland bird conservation.

This study was conducted to provide needed basic life history and nest site habitat use information as well as information about populations and potential region-wide habitat availability to enhance current and future …

Atomistic Investigation Of Anomalous Diffusion On Surfaces: A Deterministic Approach, James Wesley Mancillas

Doctoral Dissertations

The observation of anomalous diffusion rates on surfaces by recent experiments has renewed interest in diffusion mechanics. In order to provide a better understanding of the atomistic motions resulting in anomalous diffusion, we have investigated the diffusion dynamics of sodium on a copper surface using conservative molecular dynamics. The properties of diffusing adatoms transitioning between normal diffusive motion and anomalous motion have then been examined. Utilizing short time approximation Lyapunov exponents, stable cantori within chaotic manifolds are identified. At the periphery of these stable cantori from which anomalous diffusion originates, we have examined the transition properties of diffusive motions with …

Overcoming Statistical Error And Bias In Quantum Monte Carlo: Application To Metal-Doped Helium Clusters, Gary Lee Warren Jr.

Doctoral Dissertations

Quantum Monte Carlo (QMC) methods are a class of powerful computer simulation techniques for solving the many-body Schrӧdinger equation. These techniques deliver essentially exact results and boast favorable computational scaling with system size. Calculations provide a full quantum mechanical treatment and may be carried to arbitrary precision. These characteristics make QMC a promising choice for the investigation of doped helium clusters, where quantum effects are substantial.

Stochastic in nature, QMC methods are susceptible to statistical bias and error, which must be carefully controlled. Moreover, the relationship between the finite sampling error and the statistical uncertainty in observables has never been …

The Challenge Of Realizing Sustainable Natural Resource Management On Private Lands: Problems And Promise, Jamey L. Pavey

Doctoral Dissertations

Today’s natural resource problems are more complex than ever and many have yet to be effectively addressed in the United States by regulations or management policies. The challenges presented by these problems require new approaches to the governance of natural resources in the United States. These approaches must recognize that the governance of natural resources is not only a technical task, but a social process. The management of natural resources on private lands presents a unique set of problems and a unique set of opportunities to provide environmental benefits. However, without adequate incentives, landowners are unlikely to manage their land …

Syntheses, Structures, And Reactivities Of Early-Transition-Metal Silyl, Amide, And Imide Complexes, Xianghua Yu

Doctoral Dissertations

This dissertation describes syntheses, characterization, and reactivities of Groups 4 and 5 metal amide silyl complexes free of anionic π-ligands such as cyclopentadienyl (Cp).

A summary of the research in this dissertation is provided in Chapter 1. Chapter 2 reports unusual equilibria involving zirconium amides, silyl anions, and zirconium silyl complexes through amide-silyl ligand exchange reactions. Silyl anion SiBu^{tPh_{2− (}}2) was found to substitute an amide ligand in Zr(NMe2)4 (3) to give (Me2N)3Zr(SiButPh2)2− (1a) and Zr(NMe2)5− (1b) in THF. Silyl anion 2 also selectively attacks the –N(SiMe3)2 ligand in (Me2N)3Zr[N(SiMe3)2] …

Development Of Novel Synthetic Methods Utilizing Group Iii And Iv Reagents, Gang Dong

Doctoral Dissertations

This dissertation summarizes the development of novel synthetic methods involving Group III & IV reagents. These newly discovered reactions include the rhodium-catalyzed direct cross-coupling of allylic alcohols with aryl- and vinylboronic acids; palladium-catalyzed coupling reaction of Baylis-Hillman acetate adducts with both potassium organotrifluoroborate reagents and organosiloxanes; efficient syntheses of functionalized allylmetals such as allylboranes, allylsilanes, and allylgermanes; application of allylboranes to the synthesis of homoallylic alcohols; syntheses of 4-(1-alkynyl)-2(5H)-furanones and coumarins; utilization of potassium alkynyltrifluoroborates in the synthesis of conjugated enediynes; and application of potassium alkynyltrifluoroborates as reagents in the Petasis reaction.

The new synthetic methodologies involving Group III & …

Neutron Scattering Studies On Magnetism And Phonon In The Electron-Doped Nd2-Xcexcuo4 And Pr1-Xlacexcuo4, Hye Jung Kang

Doctoral Dissertations

We present comprehensive neutron scattering studies on the electron-doped superconductors Nd_2-xCe_xCuO₄ and Pr_1-xLaCe_xCuO₄ to understand how magnetic properties and phonon are related to superconductivity. For the superconducting Nd_1.85Ce_0.15CuO₄, a c-axis magnetic field enhances the commensurate antiferromagnetic order, while an ab-plane magnetic field induces spin-flop transition from the noncollinear to the collinear magnetic structure. The c-axis field-induced effect is absent in both the parent Nd₂CuO₄ and the as-grown nonsuperconducting Nd_1.85Ce_0.15CuO₄ samples. These results, combined …

Approaches To Uniform-Morphology: Polymer-Based Sers Substrates, Kathleen Sue Giesfeldt

Doctoral Dissertations

Polymer-nano-metallic-particle composites have demonstrated technological potential due to their unique optical and electrical properties. We report on composites prepared via physical vapor deposition of silver and gold onto pliable polydimethlysiloxane (PDMS) polymer. Rapid metal diffusion and nano-metallic-particle formation in a phase-separated surface layer of the PDMS creates unique sub-surface-based composites that vary in properties based on rate of deposition and average metal thickness. In addition, nano-metallicparticle spacing can be altered with fair reproducibility and reversibility by physically manipulating the composite. A practical technological characteristic of these composite materials arises from their potential to be molded into functional devices. Surface enhanced …

Experimental Studies Of Intra- And Intermolecular Chemical Structure, Cara Lynn Nygren

Doctoral Dissertations

The purpose of this study was two fold. The determination of hydrogen atom positions by X-ray diffraction methods is widely underused. With advances in instrument and computing technology, the use of X-ray diffraction experiments to accurately image the electron density associated with a hydrogen bond has become feasible. Secondly, general crystallographic computing programs analyze diffraction data by employing a spherical atom model. However, no such atom can be defined solely by a sphere when bound in a molecule. The use of spherical harmonics to model diffraction data enables a more complete description of the electron density in a molecular system. …

Obstruction Sets For Classes Of Cubic Graphs, Joshua Hughes

Doctoral Dissertations

This dissertation establishes two theorems which characterize the set of minimal obstructions for two classes of graphs. A minimal obstruction for a class of graphs is a graph that is not in the class but every graph that it properly contains, under some containment relation, is in the class. In Chapter 2, we provide a characterization of the class of cubic outer-planar graphs in terms of its minimal obstructions which are also called cubic obstructions in this setting. To do this, we first show that all the obstructions containing loops can be obtained from the complete set of loopless obstructions …

Developing A B -Tagging Algorithm Using Soft Muons At Level-3 For The Dø Detector At Fermilab, Mayukh Das

Doctoral Dissertations

The current data-taking phase of the DØ detector at Fermilab, called Run II, is designed to aid the search for the Higgs Boson. The neutral Higgs is postulated to have a mass of 117 GeV. One of the channels promising the presence of this hypothetical particle is through the decay of b-quark into a muon. The process of identifying a b-quark in a jet using muon as a reference is b-tagging with a muon tag.

At the current data taking and analysis rate, it will take long to reach the process of identifying valid events. The triggering mechanism of the …

A Numerical Method For Obtaining An Optimal Temperature Distribution In A 3d Triple-Layered Cylindrical Skin Structure, Le Zhang

Doctoral Dissertations

In recent years, it has been interesting to research hyperthermia combined with radiation and cytotoxic drugs to enhance the killing of tumors. The crucial problem is that when heating the tumor tissues, one needs to keep the surrounding normal tissue below a temperature that will produce harm. Thus, it is important to obtain the temperature field of the entire treatment region. The objective of this dissertation is to develop a numerical model for obtaining an optimal temperature distribution in a 3D triple-layered cylindrical skin structure. To this end, we pre-specify the temperatures to be obtained at the center and perimeter …

Evaluating Online Trust Using Machine Learning Methods, Weihua Song

Doctoral Dissertations

Trust plays an important role in e-commerce, P2P networks, and information filtering. Current challenges in trust evaluations include: (1) fnding trustworthy recommenders, (2) aggregating heterogeneous trust recommendations of different trust standards based on correlated observations and different evaluation processes, and (3) managing efficiently large trust systems where users may be sparsely connected and have multiple local reputations. The purpose of this dissertation is to provide solutions to these three challenges by applying ordered depth-first search, neural network, and hidden Markov model techniques. It designs an opinion filtered recommendation trust model to derive personal trust from heterogeneous recommendations; develops a reputation …

The Bipartite Clique: A Topological Paradigm For Web User Search Customization And Web Site Restructuring, Brenda F. Choyce-Miles

Doctoral Dissertations

The objective of this dissertation research is to aid the Web user to achieve his search objective at a host Web site by organizing a strongly connected neighborhood of Web pages that are thematically and spatially related to the user's search interest. Therefore, methods were developed to (1) find all Web pages at a given Web site that are thematically similar to a user's initial choice of a Web page (selected from the set of Web pages returned in response to a query by any popular search engine), and (2) organize these pages hierarchically in terms of their relevance to …

Integrated Modeling And Parallel Computation Of Laser-Induced Axisymmetric Rod Growth, Hong Lan

Doctoral Dissertations

To fully investigate a pyrolytic Laser-induced chemical vapor deposition (LCVD) system for growing an axisymmetric rod, a novel integrated three-dimensional mathematical model was developed not only to describe the heat transport in the deposit and substrate, but also to simulate the gas-phase in the heated reaction zone and its effect on growth rate. The integrated model consists of three components: the substrate, rod, and gas-phase domains. Each component is a separate model and the three components are dynamically integrated into one model for simulating the iterative and complex process of rod deposition.

The gas-phase reaction is modeled by the gas-phase …

Bootstrap Prediction Intervals For Multivariate Time Series, Florian Sebastian Rueck

Doctoral Dissertations

"The theory and methodology of obtaining bootstrap prediction intervals for univariate time series using the forward representation of the series is extended to vector autoregressive (VAR) models. Kim has shown that simultaneous prediction intervals based on the Bonferroni method and the backward representation of the time series achieve coverage close to nominal when the parameter estimates are corrected for small sample bias. To utilize his method, it is necessary to assume that the innovations are normally distributed to maintain independence of the innovations associated with the backward representation of the time series. This assumption is not necessary if the forward …

The Function Of The Stress Hormone Cortisol In Disease Susceptibility Of Channel Catfish, Ictalurus Punctatus, Todd David Sink

Doctoral Dissertations

The purpose of these studies was to examine the roles that the stress hormone cortisol plays in disease susceptibility of channel catfish, Ictalurus punctatus, to enteric septicemia of catfish (ESC). ESC is a serious disease of the channel catfish industry with annual losses in the millions. Few treatment options such as antibiotics and vaccines are available, but efficacy of treatments has proven to be limited. Deeper investigations into the physiological causes of disease in fish that accompany commercial production are needed to promote understanding of disease treatment and prevention.

Disease challenges using Edwardsiella ictaluri, the pathogenic bacterium that …

Metallic Ferroelectricity And Superconductivity In The Transition Metal Oxide Pyrochlore Cd2Re2O7, Jian He

Doctoral Dissertations

Single crystalline samples of transition metal oxide Cd₂Re₂O₇, the first superconductor among pyrochlore oxides with general formula A₂B₂O₇ and the first example of “ferroelectric metal” theoretically proposed by P.W. Anderson and E.I. Blount back in 1960s, have been grown using vapor transport and carefully characterized, regarding its chemical stoichiometry and structure. In addition to the superconductivity transition, two normal state phase transitions and the anomalous high temperature phase have been comprehensively investigated, by means of transport, thermodynamic and spectroscopy techniques. The system undergoes a subtle continuous cubic-to-tetragonal phase transition …

Electrochemical Investigation Of Anthraquinone Tagged Oligonucleotides And Electrodes, Adam N. Mullenix

Doctoral Dissertations

The DNA double helix is one of the most studied structures in modern science. These molecules provide the basic blueprint for all life as it is presently known to exist. Continuing studies of this structure, and the implications that come with them, currently yield a constantly growing base of knowledge for the study of drug interactions, specifics in the role of the sequence of bases in the DNA chain, and an understanding of the small structural abnormalities and the resulting benefits and problems in the human genome. The research presented herein attempts to examine such interactions using anthraquinone-based modifications for …

Fundamental Investigations And Analysis Of Chiral Matter Using Simple Spectroscopic Techniques, Rodney Jamel Sullivan

Doctoral Dissertations

Fundamental investigations of circular dichroism were performed on (R)-(+)-3- methylcyclopentanone, (R)-(-)-2-butylamine, and (S)-(+)-2-butylamine in the liquid and vapor phase to show that solvents often have a structure-masking effect on the circular dichroism for a given molecule. Also, the solid state circular dichroism of cubic sodium chlorate crystals was successfully measured in the midst of adverse experimental circumstances. With these single photon circular dichroism studies at hand, a new technique for measuring circular dichroism was introduced for an advanced investigation of (R)-(+)-3-methylcyclopentanone. The resonance enhanced multiphoton ionization of (R)-(+)-3-methylcyclopentanone was performed …

Com- Putational Subset Model Selection Algorithms And Applications, Xinli Bao

Doctoral Dissertations

This dissertation develops new computationally e±cient algorithms for identifying the subset of variables that minimizes any desired information criteria in model selection.

In recent years, the statistical literature has placed more and more empha- sis on information theoretic model selection criteria. A model selection crite- rion chooses model that \closely" approximates the true underlying model. Recent years have also seen many exciting developments in the model se- lection techniques. As demand increases for data mining of massive data sets with many variables, the demand for model selection techniques are be- coming much stronger and needed. To this end, we introduce …

Single Muon Production And Implications For Charm In √Sn N = 200 Gev Au+Au Collisions, Andrew Miles Glenn

Doctoral Dissertations

The PHENIX experiment, located at the Brookhaven National Laboratory’s Rela- tivistic Heavy Ion Collider, is designed to study high energy proton+proton and nu- cleus+nucleus collisions in order to characterize hot and dense nuclear matter. This dissertation presents the first analysis of single muon production in √sN N = 200 GeV Au+Au reactions. Implications of the forward rapidity measurements for charm pro- duction are discussed. Motivation for charm production measurements and the role of open charm in characterizing the medium created in relativistic heavy ion collisions are presented, and the importance of measurements at forward rapidity is established. The results of …