Physical Sciences and Mathematics Commons^™

Design Of Covalently Dynamic Films And Coatings: Analysis Of Biocatalyzed Kinetic Behavior In Soft Condensed Matter, Pirro Cipi

Dissertations

Reversibly adjusting surface and bulk properties of materials is advantageous to many applications and will vastly expand current polymer capabilities. A novel strategy was developed to render materials capable of “smart” surface and bulk properties with the aid of embedded biocatalyst and latent functional groups that are selectively activated in the presence of biocatalyst to undergo chemical transformation. The research presented herein focused on systematically characterizing the activity of lipase catalysts embedded in poly (alkyl methacrylate)s simultaneously with functionalized components, either as diffusing within the polymeric matrix or tethered to the matrix. Lipase activity, ester forming (synthetic) or ester breaking …

Synthesis And Characterization Of Acceptor: Donor Block Copolymers For Organic Photovoltaics, Brandon Cory Achord

Dissertations

Mankind needs sources of clean power. Photovoltaic (PV) cells, in use since 1839, have proven reliable and practical for certain applications. PV cell efficiency has changed over the years from 1-2% to ultra-high efficiency cells operating at efficiencies greater than 40%. Organic photovoltaics are a potential transformative technology platform. The potential for cell use, efficiency and cost are all parts of the research and development focus at the time this document was written. This research was initiated with a focus on the synthesis and understanding of the variables effecting acceptor-donor block copolymer. The self-assembled morphology resulting from varying volume ratios …

Physical And Electrical Properties Of Trimetallic Nitride Template Endohedral Metallofullerenes And Their Polymer Nanocomposites, Hanaa Mohammed Ahmed

Dissertations

The main objective of this study was characterization of pure metallic nitride fullerene, MNF, and MNF containing polymers to evaluate these materials as suitable devices for tunable applications. Polymer-fullerene nanocomposites consisting of linear polyurethane (PU) segments crosslinked via polyhydroxylated fullerenes (C₆₀ and Sc₃N@C₈₀, a metallic nitride fullerene) were prepared and characterized for their mechanical and dielectric properties using dynamic mechanical analysis (DMA) and broadband dielectric spectroscopic techniques. Polyhydroxylated fullerenes C₆₀(OH)₂₉ and Sc₃N@C₈₀(OH)₁₈ were synthesized in a high yield through a solid-state high sheer ball-milling procedure and were …

Development And Utilization Of Digital Image Correlation Techniques For The Study Of Structural Isomerism Effects On Strain Development In Epoxy Network Glasses, Stephen Robert Heinz

Dissertations

The specific aim of this dissertation is to present the findings regarding the effects of molecular structure on macroscopic mechanical performance and strain development in epoxy networks. Network molecular structure was altered through monomer isomerism and crosslink density/molecular weight between crosslinks. The use of structural isomerism provided a pathway for altering mechanical performance while maintaining identical chemical composition within the network. Isomerism was investigated primarily by the curing of diglycidyl ether of bisphenol A (DGEBA) using either the para- or meta-substituted derivatives of diaminodiphenyl sulfone (DDS). Additional insights into isomerism were gained through the investigation of networks composed of either …

Geometric Structures On Matrix-Valued Subdivision Schemes, James J. Smith

Dissertations

Surface subdivision schemes are used in computer graphics to generate visually smooth surfaces of arbitrary topology. Applications in computer graphics utilize surface normals and curvature. In this paper, formulas are obtained for the first and second partial derivatives of limit surfaces formed using 1-ring subdivision schemes that have 2 by 2 matrix-valued masks. Consequently, surface normals, and Gaussian and mean curvatures can be derived. Both quadrilateral and triangular schemes are considered and for each scheme both interpolatory and approximating schemes are examined. In each case, we look at both extraordinary and regular vertices. Every 3-D vertex of the refinement polyhedrons …

Rational Ligand Design For Potential Applications In Transition Metal Catalysis, Sergey L. Sedinkin

Dissertations

Strategies to influence the steric and electronic properties of three classes of ligands were investigated. First, a compound class known as amino-dithiaphospholanes was studied. It is structurally related to phosphoramidites, which have been successfully applied in catalysis. The synthesis of amino-dithiaphospholanes was envisaged as an approach to electronically tuned phosphoramidites. General access to a variety of structurally modified amino-dithiaphospholanes from commercially available starting materials was developed. The electron donating properties of the new ligands were characterized by NMR. They were found to be more electron-donating than the corresponding phosphoramidites. The coordination chemistry of amino-dithiaphospholanes was investigated by synthesis of a …

Extensions Of Snomed Taxonomy Abstraction Networks Supporting Auditing And Complexity Analysis, Duo Wei

Dissertations

The Systematized Nomenclature of Medicine – Clinical Terms (SNOMED CT) has been widely used as a standard terminology in various biomedical domains. The enhancement of the quality of SNOMED contributes to the improvement of the medical systems that it supports.

In previous work, the Structural Analysis of Biomedical Ontologies Center (SABOC) team has defined the partial-area taxonomy, a hierarchical abstraction network consisting of units called partial-areas. Each partial-area comprises a set of SNOMED concepts exhibiting a particular relationship structure and being distinguished by a unique root concept. In this dissertation, some extensions and applications of the taxonomy framework are considered. …

Security Systems Based On Gaussian Integers : Analysis Of Basic Operations And Time Complexity Of Secret Transformations, Aleksey Koval

Dissertations

Many security algorithms currently in use rely heavily on integer arithmetic modulo prime numbers. Gaussian integers can be used with most security algorithms that are formulated for real integers. The aim of this work is to study the benefits of common security protocols with Gaussian integers. Although the main contribution of this work is to analyze and improve the application of Gaussian integers for various public key (PK) algorithms, Gaussian integers were studied in the context of image watermarking as well.

The significant benefits of the application of Gaussian integers become apparent when they are used with Discrete Logarithm Problem …

The Effects Of Periodic And Non-Periodic Inputs On The Dynamics Of A Medial Entorhinal Cortex Layer Ii Stellate Cell Model, Dongwook Kim

Dissertations

Various neuron types exhibit sub-threshold and firing frequency resonance in which the sub-threshold membrane potential or firing frequency responses to periodic inputs peak at a preferred frequency (or frequencies). Previous experimental work has shown that medial entorhinal cortex layer II stellate cells (SCs) exhibit sub-threshold and firing frequency resonance in the theta frequency band (4 - 10 Hz). In this thesis we seek to understand the biophysical and dynamic mechanism underlying these phenomena and how they are related. We studied the effects of sinusoidal current and synaptic conductance inputs at various frequencies, with and without noise, on the supra-threshold dynamics …

Energy Propagation In Jammed Granular Matter, Xiaoni Fang

Dissertations

The systems built from dense granular materials are very important due to their relevance to a number of technological and other fields. However, they are difficult to study in particular due to a lack of accurate continuum description. In this work, studies on these systems are presented using discrete element simulations that model the granular particles as soft, elastic, and frictional disks which interact when in contact. These simulations are used for the purpose of analyzing a few granular systems with the main emphasis on understanding phenomena of energy and force propagation.

Analysis of energy propagation in a two-dimensional disordered …

Investigation On Advanced Image Search Techniques, Abhishek Verma

Dissertations

Content-based image search for retrieval of images based on the similarity in their visual contents, such as color, texture, and shape, to a query image is an active research area due to its broad applications. Color, for example, provides powerful information for image search and classification. This dissertation investigates advanced image search techniques and presents new color descriptors for image search and classification and robust image enhancement and segmentation methods for iris recognition.

First, several new color descriptors have been developed for color image search. Specifically, a new oRGB-SIFT descriptor, which integrates the oRGB color space and the Scale-Invariant Feature …

Synthesis Of (±)-Cyclophostin, (±)-Cyclipostin P, Their Phosphonate Analogs And New Chemistry Of Vinyl Phosphonates, Raj Kumar Malla

Dissertations

This work is divided into 2 parts: a) total synthesis of (±)-cyclophostin, (±)-cyclipostin P and their monocyclic analogs b) development of a metathesis based methodology for transformation of vinyl phosphonates. Cyclophostin (1) and cyclipostins (2) are bioactive natural bicyclic organophosphates. Cyclophostin is a powerful inhibitor of acetyl cholinesterase (AChE), whereas members of the cyclipostins are potent inhibitors of hormone sensitive lipase (HSL). Cyclophostin (1) and cyclipostin (2) have the same structural core unit, but different phosphate ester substituents. While cyclophostin is a methyl ester, the members of the cyclipostins are phosphate esters of different alkyl groups of various length and …

Self-Repairable Polymeric Networks: Synthesis And Network Design, Biswajit Ghosh

Dissertations

This dissertation describes the design, synthesis and development of a new class of polymeric networks that exhibit self-repairing properties under UV exposure. It consists of two parts: (a) modification and synthesis of oxetane (OXE), and oxolane (OXO) substituted chitosan (CHI) macromonomer, and (b) design, and synthesis of self-repairing polyurethane (PUR) networks consisting of modified chitosan. Unmodified CHI consisting of acetamide (-NHCOCH₃), primary hydroxyl (-OH), and amine (-NH₂) functional groups were reacted with OXE or OXO compounds under basic conditions in order to substitute the 1° –OH groups, and at the same time, convert -NHCOCH₃ functionalities …

Precision Synthesis Of Functional Materials Via Raft Polymerization And Click-Type Chemical Reactions, Joel Diez Flores

Dissertations

The need to tailor polymeric architectures with specific physico-chemical properties via the simplest, cleanest, and most efficient synthetic route possible has become the ultimate goal in polymer synthesis. Recent progress in macromolecular science, such as the discoveries of controlled/“living” free radical polymerization (CRP) methods, has brought about synthetic capabilities to prepare (co)polymers with advanced topologies, predetermined molecular weights, narrow molecular weight distributions, and precisely located functional groups. In addition, the establishment of click chemistry has redefined the selected few highly efficient chemical reactions that become highly useful in post-polymerization modification strategies. Hence, the ability to make well-defined topologies afforded by …

Monte Carlo Simulation Of Electron-Induced Air Fluorescence Utilizing Mobile Agents: A New Paradigm For Collaborative Scientific Simulation, Christopher Daniel Walker

Dissertations

A new paradigm for utilization of mobile agents in a modular architecture for scientific simulation is demonstrated through a case study involving Monte Carlo simulation of low energy electron interactions with molecular nitrogen gas. Design and development of Monte Carlo simulations for physical systems of moderate complexity can present a seemingly overwhelming endeavor. The researcher must possess or otherwise develop a thorough understanding the physical system, create mathematical and computational models of the physical system’s components, and forge a simulation utilizing those models. While there is no single route between a collection of physical concepts and a Monte Carlo simulation …

The Role Of Amyloid-Beta Assembly State In Monocyte Maturation And Smooth Muscle Cell Degeneration, Nikkilina Renee Crouse

Dissertations

Alzheimer's Disease (AD) is a progressive, neurodegenerative disorder which is ranked as a leading cause of death among Americans. AD is characterized by the presence of intracellular neurofibrillary tangles and extracellular plaques made of amyloid ß (Aß). Together these pathologies lead to severe memory impairment in patients, but research has implicated the presence of the Aß deposits as likely causes for AD progression. Aß is produced through the proteolytic cleavage of the integral membrane amyloid precursor protein, which occurs through the action of beta- and gamma-secretases and produces 39-43 amino acid Aß peptides. In AD, the Aß plaques are comprised …

Development Of New Strategies For Expeditious Oligosaccharide Synthesis, Sophon Kaeothip

Dissertations

The important role that carbohydrates play in biology and medicine has been the major incentive for devising new methods for chemical and enzymatic glycosylation. The chemical approach to oligosaccharides involves multiple synthetic steps and the development of new strategies that allow for streamlining the synthesis of these complex biomolecules is a significant area of research. The aim of this doctoral dissertation is to develop new reagents and efficient methodologies for oligosaccharide synthesis. It was found that siver(I) tetrafluoroborate can be used as a powerful activator of various glycosyl donors for oligosaccharide synthesis. This study evolved into the development of a …

Some Contributions To Modeling Usage Sensitive Warranty Servicing Strategies And Their Analyses, Rudrani Banerjee

Dissertations

Providing a warranty as a part of a product's sale is a common practice in industry. Parameters of such warranties (e.g., its duration limits, intensity of use) must be carefully specified to ensure their financial viability. A great deal of effort has been accordingly devoted in attempts to reduce the costs of warranties via appropriately designed strategies to service them. many such strategies, that aim to reduce the total expected costs of the warrantor or / and are appealing in other ways such as being more pragmatic to implement - have been suggested in the literature. Design, analysis and optimization …

Using Feed-Forward Networks To Infer The Activity Of Feedback Neuronal Networks, Xinxian Huang

Dissertations

The nervous system is one of the most important organ systems in a multicellular body. Animals, including human beings perceive, learn, think and deliver motion instructions through their nervous system. The basic structural units of the nervous system are individual neurons which constitute different neuronal networks with distinct functions. In each network, constituent neurons are coupled with different connection patterns, for example, some neurons send feed-forward information to the coupling neurons while others are mutually coupled. Because it is often difficult to analyze large interconnected feedback neuronal networks, it is important to derive techniques to reduce the complexity of the …

Enhanced Membrane Distillation : Analytical And Deionization Applications, Ken Gethard

Dissertations

Membrane distillation (MD) is a newer technology that is being investigated for applications such as seawater desalination and concentration of fruit and sucrose solutions. The major advantage of MD over traditional thermal distillation is that it requires a substantially lower thermal energy requirement to power the process. This allows low grade energy sources such as waste heat or solar energy to be used with MD. Compared to concentration processes such as reversed osmosis or ion-exchange, MD does not require specialized equipment, high electrical consumption, the use of strong acids and bases nor does it generate hazardous waste as a by-product. …

Anti-Solvent Precipitation And Subsequent Film Formation Of Hydrophobic Drugs For Drug Delivery, Xiangxin Meng

Dissertations

It is estimated that about forty percent of the drug molecules being developed by the pharmaceutical industry are hydrophobic in nature, leading to poor water solubility and bioavailability in the gastrointestinal tract. Dissolution is a limiting factor in their in vivo performance, and increasing their dissolution rate is a major challenge. It has been proven that the dissolution rate is directly proportional to the specific surface area, which can be effectively increased by reducing the particle size. Therefore, considerable efforts have gone into developing reliable and efficient methods for the manufacture of fine particles. Particle size reduction technologies such as …

Confidence Bands For Survival Functions Under Semiparametric Random Censorship Models, Peixin Zhang

Dissertations

In medical reports point estimates and pointwise confidence intervals of parameters are usually displayed. When the parameter is a survival function, however, the approach of joining the upper end points of individual interval estimates obtained at several points and likewise for the lower end points would not produce bands that include the entire survival curve with a given confidence. Simultaneous confidence bands, which allow confidence statements to be valid for the entire survival curve,would be more meaningful

This dissertation focuses on a novel method of developing one-sample confidence bands for survival functions from right censored data. The approach is model- …

Analysis Of Mueller Matrices Of Metamaterials And Multiferroics, Paul D. Rogers

Dissertations

The optical spectra of complex materials such as magnetic-dielectric media, magnetoelectric and multiferroic crystals, materials with intrinsic chirality, and metamaterials are studied. These media are important both for: (i) their interesting optical effects, such as Negative Index of Refraction (NIR) and impedance matching; and (ii) possible device applications such as switching devices and anti-reflection coatings. Proper characterization of complex materials requires advanced spectroscopic approaches and the development of theoretical models for data analysis. Berreman’s 4´4 matrix formalism is used to derive forward models for the optical spectra of Reflectivity, Transmission, Rotating Analyzer Ellipsometry (RAE), and Mueller Matrices (MM). The forward …

Development Of Advanced Algorithms To Detect, Characterize And Forecast Solar Activities, Yuan Yuan

Dissertations

Study of the solar activity is an important part of space weather research. It is facing serious challenges because of large data volume, which requires application of state-of-the-art machine learning and computer vision techniques. This dissertation targets at two essential aspects in space weather research: automatic feature detection and forecasting of eruptive events.

Feature detection includes solar filament detection and solar fibril tracing. A solar filament consists of a mass of gas suspended over the chromosphere by magnetic fields and seen as a dark, ribbon-shaped feature on the bright solar disk in Hα (Hydrogen-alpha) full-disk solar images. In this dissertation, …

High-Order Adaptive Methods For Computing Invariant Manifolds Of Maps, Jacek K. Wrobel

Dissertations

The author presents efficient and accurate numerical methods for computing invariant manifolds of maps which arise in the study of dynamical systems. In order to decrease the number of points needed to compute a given curve/surface, he proposes using higher-order interpolation/approximation techniques from geometric modeling. He uses B´ezier curves/triangles, fundamental objects in curve/surface design, to create adaptive methods. The methods are based on tolerance conditions derived from properties of B´ezier curves/triangles. The author develops and tests the methods for an ordinary parametric curve; then he adapts these methods to invariant manifolds of planar maps. Next, he develops and tests the …

Markovian And Stochastic Differential Equation Based Approaches To Computer Virus Propagation Dynamics And Some Models For Survival Distributions, Lianzhe Xu

Dissertations

This dissertation is divided in two Parts. The first Part explores probabilistic modeling of propagation of computer 'malware' (generally referred to as 'virus') across a network of computers, and investigates modeling improvements achieved by introducing a random latency period during which an infected computer in the network is unable to infect others. In the second Part, two approaches for modeling life distributions in univariate and bivariate setups are developed.

In Part I, homogeneous and non-homogeneous stochastic susceptible-exposed-infectious- recovered (SEIR) models are specifically explored for the propagation of computer virus over the Internet by borrowing ideas from mathematical epidemiology. Large computer …

Sequential Bayesian Filtering For Spatial Arrival Time Estimation, Rashi Jain

Dissertations

Locating and tracking a source in an ocean environment as well as estimating environmental parameters of a sound propagation medium is of utmost importance in underwater acoustics. Matched field processing is often the method of choice for the estimation of such parameters. This approach, based on full field calculations, is computationally intensive and sensitive to assumptions on the structure of the environment. As an alternative, methods that use only select features of the acoustic field for source localization and environmental inversion have been proposed. The focus here is on inversion using arrival times of identified paths within recorded time-series. After …

Applications Of Stochastic Simulation In Two-Stage Multiple Comparisons With The Best Problem And Time Average Variance Constant Estimation, Dibyendu Chakrabarti

Dissertations

In this dissertation, we study two problems. In the first part, we consider the two-stage methods for comparing alternatives using simulation. Suppose there are a finite number of alternatives to compare, with each alternative having an unknown parameter that is the basis for comparison. The parameters are to be estimated using simulation, where the alternatives are simulated independently. We develop two-stage selection and multiple-comparison procedures for simulations under a general framework. The assumptions are that each alternative has a parameter estimation process that satisfies a random- time-change central limit theorem (CLT), and there is a weakly consistent variance estimator (WCVE) …

Numerical And Asymptotic Modeling Of Evolving Nonlinear Ocean Surface Wave Fields, Matt Malej

Dissertations

The main focus of this dissertation is the asymptotic and numerical modeling of nonlinear ocean surface wave fields. In particular, a development of an accurate numerical model for the evolution of nonlinear ocean waves, including extreme waves known as Rogue/Freak waves. Due to their elusive and destructive nature, the media often portrays Rogue waves as unimaginatively huge and unpredictable monsters of the sea. To address these concerns, derivations of asymptotically reduced models, based on the small wave steepness assumption, are presented and their corresponding numerical simulations via a Fourier pseudo-spectral method are discussed. The simulations are initialized with a well-known …

Uniform Heating Of Thin Ceramic Slabs In A Multimode Microwave Cavity, Shuchi Agrawal

Dissertations

Two-dimensional reaction diffusion equations, which contain a functional and an inhomogeneous source term, are good models for describing microwave heating of thin ceramic slabs and cylinders in a multi mode, highly resonant cavity. A thin ceramic slab situated in a TEN03 rectangular cavity modeled in the small Biot number limit and a thin silicon wafer situated in a TM101 cylindrical cavity modeled in the small fineness ratio limit are studied to gain insight into the dynamics of the heating process. The evolution of temperature is governed by a two-dimensional reaction diffusion equation and a spatially non-homogeneous reaction term. Numerical methods …