Physical Sciences and Mathematics Commons^™

Relation Between The Adsorption Behavior And Bulk Complexation In Oppositely Charged Polyelectrolyte-Surfactant Systems: Effect Of Polyelectrolyte Concentration, Molecular Weight, Charge Localization And Backbone Rigidity/Hydrophobicity, Vipul Suhas Padman

Dissertations

Due to a wide range of applications, much emphasis has been placed on understanding the physicochemical behavior of polyelectrolyte/surfactant complexes, both at air-water interface and in the bulk. However, the correlation between the adsorption behavior and complexation in the bulk is less explored. In this research, this correlation is investigated and its dependence on polyelectrolyte concentration, molecular weight, charge localization and backbone rigidity and hydrophobicity is studied. The polyelectrolyte concentration is normalized with respect to it critical overlap concentration in order to compare the polymer in same concentration regime. Different polyelectrolyte systems were used to analyze the polyelectrolyte structural effect: …

Synthesis And Characterization Of Polyisobutylene-Block-Polyamides As Novel Thermoplastic Elastomers, Lauren Renee Kucera

Dissertations

Academic research has focused on two main areas of the living carbocationic polymerization (LCP) of isobutylene (IB): (1) the in-depth study and understanding of mechanistic features of the polymerization, and (2) the utilization and manipulation of the unique aspects of PIB in order to produce practically useful polymeric materials. The research included in this dissertation focuses mainly on the latter objective. This work details three main areas of research: (1) the copolymerization of PIB and polyamides (PA) to form novel thermoplastic elastsomers (TPEs), (2) the mechanical, physical and thermal properties of the novel PIB-PA materials, and (3) the use of …

A Pattern In The Lusternik-Schnirelmann Category Of Rational Spaces, Julie Dare Houck

Dissertations

The Lusternik-Schnirelmann (or LS) category of a space is one less than the number of contractible open sets with which we can cover the space. If we look at the LS categories of the skeleta of a CW complex, we find a sequence of dimensions where the LS category changes. I discuss whether certain of these "category sequences" (defined in the paper, "Categorical Sequences", by Nendorf, Scoville, and Strom) could be realized as the categorical sequences of rational spaces. I first reduce from looking at all rational spaces to only Postnikov sections of finite wedges of spheres. Using the Leray-Serre …

Iterative Solvers For Large, Dense Matrices, Eowyn Wilhelmina Cenek

Dissertations

Stochastic Interpolation (SI) uses a continuous, centrally symmetric probability distribution function to interpolate a given set of data points, and splits the interpolation operator into a discrete deconvolution followed by a discrete convolution of the data. The method is particularly effective for large data sets, as it does not suffer from the problem of oversampling, where too many data points cause the interpolating function to oscillate wildly. Rather, the interpolation improves every time more data points are added. The method relies on the inversion of relatively large, dense matrices to solve Annx = b for x. Based on the probability …

Ultrafast Dynamics And Two-Photon Absorption Properties Of Chromophores At Interfaces, Semere Ghebru Bairu

Dissertations

Materials with large two-photon absorption (2PA) cross-sections found applications in several areas such as sensor protection, 3D micro/nano fabrication, photodynamic therapy, optical data-storage, multi-photon sensing, multi-photon microscopy and imaging. Several successful research strategies were developed in literature to achieve 2PA materials with enhanced cross-sections. However, the obtained cross-sections are far from adequate and there is a need to develop new strategies. In a parallel development, numerous research efforts were focused on studying the dynamics of interfacial charge-transfer (ICT) across chromophoresemiconductor interfaces, especially in the context of dye-sensitized solar cells. While investigating the fundamentals of ICT, it was found that these …

An Embodied Perspective Of Expertise In Solving The Problem Of Making A Geologic Map, Caitlin Norah Callahan

Dissertations

The task of constructing a geologic map is a cognitively and physically demanding field-based problem. The map produced is understood to be an individual’s two-dimensional interpretation or mental model of the three-dimensional underlying geology. A popular view within the geoscience community is that teaching students how to make a geologic map is valuable for preparing them to deal with disparate and incomplete data sets, for helping them develop problem-solving skills, and for acquiring expertise in geology. Few previous studies have focused specifically on expertise in geologic mapping. Drawing from literature related to expertise, to problem solving, and to mental models, …

In Situ Quenching And Post-Polymerization Modification Of Telechelic Polyisobutylene, Todd Raymond Hartlage

Dissertations

Polyisobutylene (PIB) is a saturated hydrocarbon elastomer that can only be produced by cationic polymerization. The water-initiated, chain transfer controlled synthesis conducted on an industrial scale produces monofunctional PIB with mixed olefin end groups. Living cationic techniques produce mono- and di-functional telechelic PIB. In situ quenching is the process of adding functional molecules to the polymerization reactor after all monomer is consumed. These quencher species bond to the chain ends, installing their latent functionality onto the polymer chain. To date, all quenchers utilized have been soft π-nucleophiles.

In the first project, free thiols, both aromatic and aliphatic, are shown to …

Biophysical Understanding Of Novel Synthetic Amyloid-Β (Aβ) Prions In Alzheimer's Disease, Amit Kumar

Dissertations

Oligomers of amyloid-β (Aβ) peptide are the primary toxic agents that play a pivotal role in the pathogenesis of Alzheimer’s disease (AD). Oligomers are the intermediates formed during the Aβ aggregation process leading up to insoluble fibrils. It is important to know that oligomers can also be formed via pathways that do not lead to fibril formation. Such ‘off-pathway’ oligomers would have significantly longer half-lives than the ‘on-pathway’ ones, which may result in prolonged toxicity to neuronal cells. Furthermore, neither the mechanism of neurotoxicity nor the potential mechanisms of propagation and proliferation to neighboring cells are well understood. Moreover, recent …

A Robust Estimate For The Bifurcating Autoregressive Model With Application To Cell Lineage Data, Tamer M. E. Elbayoumi

Dissertations

The bifurcating autoregressive model (BAR) is commonly used to model binary tree data. One application for this model relates to cell lineage data in biology. The purpose of studying the cell lineage process is to know whether the observed correlations between related cells are due to similarities in the environmental, inherited effects, or a combination of both of them. Because outliers in this kind of data are quite common, the need for a robust estimation procedure is necessary. A weighted L1 (WL1) estimate for estimating the parameters of the BAR model is considered. When the weights are constant, the estimate …

Organic Solar Cells Based On High Dielectric Constant Materials: An Approach To Increase Efficiency, Khalil Jumah Tawfiq Hamam

Dissertations

The efficiency of organic solar cells still lags behind inorganic solar cells due to their low dielectric constant which results in a weakly screened columbic attraction between the photogenerated electron-hole system, therefore the probability of charge separating is low. Having an organic material with a high dielectric constant could be the solution to get separated charges or at least weakly bounded electron-hole pairs. Therefore, high dielectric constant materials have been investigated and studied by measuring modified metal-phthalocyanine (MePc) and polyaniline in pellets and thin films. The dielectric constant was investigated as a function of temperature and frequency in the range …

Examining Antarctica From A Geodynamic Perspective: Backstripping, Ice Thickness, Tectonics And Erosion, Travis Gary Hayden

Dissertations

I have applied the principles of basin analysis and geodynamics to several cores recovered from on or near the Antarctic continent to answer 2 independent questions about the tectonic evolution of Antarctica; as well as estimate the thickness of the Antarctic Ice Sheet at the Last Glacial Maximum.

I developed, and applied a modification of the backstripping modeling technique to compensate for the loading and erosion of glacial ice at the AND-1B site by combining a backstripping driven inverse model, with a driven ice-load model. This modification allowed me to identify and constrain the timing of major pulses of subsidence …

Investigations Into B-O Defect Formation-Dissociation In Cz-Silicon And Their Effect On Solar Cell Performance, Prakash M. Basnyat

Dissertations

About 30% of the total market share of industrial manufacture of silicon solar cells is taken by single crystalline Czochralski (CZ) grown wafers. The efficiency of solar cells fabricated on boron-doped Czochralski silicon degrades due to the formation of metastable defects when excess electrons are created by illumination or minority carrier injection during forward bias. The recombination path can be removed by annealing the cell at about 200° C but recombination returns on exposure to light.

Several mono-crystalline and multi-crystalline solar cells have been characterized by methods such as laser beam induced current (LBIC), Four-Probe electrical resistivity etc. to better …

Concept Graphs: Applications To Biomedical Text Categorization And Concept Extraction, Said Bleik

Dissertations

As science advances, the underlying literature grows rapidly providing valuable knowledge mines for researchers and practitioners. The text content that makes up these knowledge collections is often unstructured and, thus, extracting relevant or novel information could be nontrivial and costly. In addition, human knowledge and expertise are being transformed into structured digital information in the form of vocabulary databases and ontologies. These knowledge bases hold substantial hierarchical and semantic relationships of common domain concepts. Consequently, automating learning tasks could be reinforced with those knowledge bases through constructing human-like representations of knowledge. This allows developing algorithms that simulate the human reasoning …

Novel Color And Local Image Descriptors For Content-Based Image Search, Sugata Banerji

Dissertations

Content-based image classification, search and retrieval is a rapidly-expanding research area. With the advent of inexpensive digital cameras, cheap data storage, fast computing speeds and ever-increasing data transfer rates, millions of images are stored and shared over the Internet every day. This necessitates the development of systems that can classify these images into various categories without human intervention and on being presented a query image, can identify its contents in order to retrieve similar images.

Towards that end, this dissertation focuses on investigating novel image descriptors based on texture, shape, color, and local information for advancing content-based image search. Specifically, …

Mechanical, Electronic And Optical Properties Of Multi-Ternary Semiconductor Alloys, Dongguo Chen

Dissertations

The ability to obtain tunable properties with composition makes multi-ternary alloys extremely useful for a variety of applications in semiconductor devices and is of significant interest in experimental and theoretical research. This dissertation investigates the mechanical, electronic and optical properties of multi-ternary, i.e., binary, ternary and quaternary, semiconductor alloys using analytical methods and first-principles calculations.

For the calculations of mechanical properties, existing models on the average shear modulus of III-V & II-VI binary semiconductors are revised. New expressions are developed for the average Young’s modulus as well as the shear modulus and Young’s modulus on (111) plane for these compounds. …

Stability And Precipitation Of Diverse Nanoparticles, Chintal Desai

Dissertations

Nanotechnology is a rapidly growing industry that is exploiting the novel characteristics of materials manufactured at the nanoscale. Carbon based nanomaterials such as Carbon Nanotubes (CNTs) and Detonation Nanodiamond (DND) possess unique properties and find a wide range of industrial applications. With the advent of mass production of such materials, there is a possibility of contamination of water resources. Depending on the surface properties and structures, they might aggregate and settle down, or be dispersed and transported by the water. Therefore, there is a need to develop an understanding of the fate of such materials in aqueous media. The understanding …

The Application Of Bayesian Adaptive Design And Markov Model In Clinical Trials, Xiaoyu Lu

Dissertations

In this research, two new designs in clinical trials are proposed. The first problem is a new Bayesian adaptive dose-finding design and its application in an oncology clinical trial. This design is used for phase IB studies with the biomarker as the endpoint and with the fewer patients. The second problem is another new Bayesian adaptive dose-finding design with longitudinal analysis and its application in phase II depression clinical trial. This design is best fit for phase II dosing-finding clinical trials with clinical endpoints. MTD information has been obtained before the trials.

In adaptive dose-finding clinical trials, the strategy is …

Application Of Hydrogen Peroxide As Brown Tide Bloom Control Agent, Varunpreet Randhawa

Dissertations

Harmful algal blooms (HABs) are growing problem across the globe. One such HAB that’s recurring in the coastal waters of New York and New Jersey since mid-1980s, and has been reported in other countries recently, is brown tide bloom. The causal organism is a minute pel agophyte (cell diameter ~- 2µ m) Aureococcus anophagefferens. The brown tide bloom has been responsible for the severe ecological damage and economic loss (e.g. shellfishery) in the affected areas. This research focuses on finding a method to control brown tide blooms and explores the potential of natural chemical biocide hydrogen peroxide (H_{2 …}

Study Of Deep Level Defects Of N+-Cds/P-Cdte Solar Cells, Poonam Rani Kharangarh

Dissertations

Among various photovoltaic materials, polycrystalline cadmium telluride thin film is now the most promising material, due to its low production cost excellent stability and reliability. Current-voltage and capacitance-voltage measurements of CdTe photovoltaic devices at different temperatures can provide valuable information about non-idealities in the n-p semiconductor junction. There are certain limitations which limit the efficiency of CdTe solar cells. There is no real distinction between defects and impurities in CdTe solar cells as both act as beneficial dopants or detrimental traps unlike Si where intentional shallow dopants and traps are distinctly different. Therefore, the role of defect states on CdTe …

Study Of Elementary Reactions Of Combustion Importance At Elevated Temperatures And Pressures, Manuvesh Sangwan

Dissertations

The aim of the present study is to study the kinetics of elementary reactions of combustion importance at elevated temperatures and pressures. High pressure is encountered in many systems of practical importance such as internal combustion engines and rocket combustion chambers. Several reactions of OH, CH₃ and HO₂ radicals are studied. The pressure range covered in this study is 1 - 100 bar and the temperature range is 292 - 834 K. The experimental approach used is laser photolysis coupled to UV transient absorption spectroscopy. A unique high pressure heatable flow reactor is employed and a novel approach …

Thermochemistry Reaction Paths And Oxidation Kinetics On Ketonyl And Aldehydic Nitrogen Oxides, Propene And Isooctane: A Theoretical Study, Suarwee Snitsiriwat

Dissertations

Thermochemical properties for several atmospheric and combustion related species are determined using computational chemical methods coupled with fundamentals of thermodynamics and statistical mechanics. Enthalpies of formation (ΔH_f°₂₉₈) are determined using isodesmic reaction analysis at the CBS-QB3 composite and the B3LYP density functional methods. Entropies (S°₂₉₈) and heat capacities (Cp°(T)) are determined using geometric parameters and vibration frequencies; internal rotor contributions are included in S and Cp(T) values in place of torsion frequencies. Kinetic parameters are calculated versus pressure and temperature for the chemical activated …

Escherichia Coli 2-Oxoglutarate Dehydrogenase Multienzyme Complex: E1 And E2 Substrate Specificty, E1 Carboligase Activity, And E2 Interchain Succinyl Transfer, Da Jeong Shim

Dissertations

Escherichia coli (E. coli) 2-oxoglutarate dehydrogenase multienzyme complex (OGDHc) contains three components: a thiamin di phosphate (ThD P) dependent 2-oxogl utarate dehydrogenase (E1 o), a di hydrol i poylsucci nyl transferase (E2o), and a di hydrol i poyl dehydrogenase (E3). The first two components carry out the principal reactions for succinyl CoA formation while the third one reoxidizes dihydrolipoamide to lipoamide. This mechanism is similar to other 2-oxoacid dehydrogenase complexes, including pyruvate dehydrogenases (PDHc) and branched-chain dehydrogenases.

E1o of the E. coli OGDHc was engineered to accept unnatural substrates. The natural substrate for E1 o is 2-oxogl utarate …

Computational Thermochemistry Of Hydrocarbons, Oxygenates, Cyclic Alkanes, And Furans, Jason Michael Hudzik

Dissertations

Fundamental thermochemical properties including enthalpies (ΔH°_{f 298}), entropies (S° (T)), heat capacities (C_p(T)), and bond dissociation energies (BDEs) for several common and complex hydrocarbon fuel species are determined using computational chemical methods. ΔH° _{f 298} values are calculated using work reactions with the B3LY P (6-31 G(d,p) and 6-311G(2d,2p) basis sets), CBS-QB3, and G3MP2B3 calculation methods. Structures, moments of inertia, vibrational frequencies, and internal rotor potentials are calculated for contributions to entropies and heat capacities. Kinetic rate parameters are calculated for hydrogen abstraction and chemical activation reactions.

Recommended ΔH° …

A Statistical Study Of Plasmawaves And Energetic Particles In The Outer Magnetosphere, Kyungguk Min

Dissertations

The Earth magnetosphere contains energetic particles undergoing specific motions around Earth’s magnetic field, and interacting with a variety of waves. The dynamics of energetic particles are often described in terms of three kinds of adiabatic invariants. Energetic electrons are often unstable to the whistler-mode chorus waves, and ions, to the electromagnetic ion cyclotron (EMIC) instability. These waves play an important role in the dynamics of the magnetosphere by energizing electrons to form a radiation belt, extracting energy from the hot, anisotropic ions and causing pitch angle scattering of energetic ions and relativistic electrons into the loss cone. EMIC waves correspond …

Mathematical Models For Bistable Nematic Liquid Crystal Displays, Chenjing Cai

Dissertations

Bistable Liquid Crystal Displays (LCDs) offer the potential for considerable power savings, compared with conventional (monostable) LCDs. The existence of two (or more) stable field-free states that are optically-distinct means that contrast can be maintained in a display without an externally-applied electric field. An applied field is required only to switch the device from one state to the other, as needed. This dissertation focuses on theoretical models of a possible bistable nematic device, whose operating principle relies on controlling surface anchoring conditions. Switching between the two stable steady states is achieved by application of a transient electric field. A 1D …

A Numerical Method For Electro-Kinetic Flow With Deformable Interfaces, Manman Ma

Dissertations

We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid-fluid interface, a screening cloud of ions develops and forms an electro-chemical double layer or ‘Debye layer’. The applied electric field acts on the ionic cloud it induces, resulting in a strong slip flow near the interface. This is known as ‘induced-charge electro-kinetic flow’, and is an important phenomenon in microfluidic applications and in the manipulation of biological cells. The models with two different cases including the fast or slow charging time scales are studied both analytically and numerically. We address a …

Gp Representation Space Reduction Using A Tiered Search Scheme, John Joseph Aleshunas

Dissertations

The size and complexity of a GP representation space is defined by the set of functions and terminals used, the arity of those functions, and the maximal depth of candidate solution trees in the space. Practice has shown that some means to reduce the size or bias the search must be provided. Adaptable Constrained Genetic Programming (ACGP) can discover beneficial substructures and probabilistically bias the search to promote the use of these substructures. ACGP has two operating modes: a more efficient low granularity mode (1st order heuristics) and a less efficient higher granularity mode (2nd order heuristics). Both of these …

Synthesis And Characterization Of Luminescent Cyclic Germanium Compounds, Teresa Lynn Bandrowsky

Dissertations

The vision in the field of organic electronics is the realization of flexible, easily manufactured, low cost optoelectronics for use in organic light emitting diodes (OLEDs) for large area displays and lighting applications, organic photovoltaic cells, and organic field-effect transistors. The active layers within such devices are composed of semiconducting small molecules or polymers. The rich chemistry of new π-conjugated materials holds the key to continued progress by allowing the material properties of organic semiconductors to be readily tuned towards application specific demands. At the core of this subject matter is how to modify the electronic structures of π-conjugated molecules …

The Investigation Of Iron(Ii) Complexes And Their Catalytic Applications, Matthew Joseph Lenze

Dissertations

Several new η5-indenyl (Ind) complexes of iron featuring phosphinooxazoline (PHOX) ligands were synthesized and spectroscopically characterized and in a few cases structurally. The complexes were synthesized using phosphinooxazoline ligands and the corresponding iron precursor [Fe(η5-Ind) I(CO)2], yielding novel piano-stool iron complexes of the general formula [Fe(η5-Ind)(CO)(PHOX)]+ in 73% to 81% isolated yields. The complexes were tested for their efficacy in a carbon-carbon bond formation known as the Mukaiyama aldol reaction. The [Fe(η5-Ind)(CO)(PHOX)]+ complexes were capable of activating the carbonyl of aromatic aldehydes towards by attack 1-(tertbutyldimethylsilyloxy)-1-methoxyethene to form the expected silyl protected β-hydroxyesters. In these complexes, the η5-η3 haptotropic shift …

Microglial Activation By Amyloid-Beta, Geeta Subhash Paranjape

Dissertations

Paranjape, Geeta S.,Ph.D.,University of Missouri-Saint Louis, May 2012. Aβ(1-42) Protofibrils But Not Fibrils Activate Microglia. Major Professor: Michael R. Nichols. One of the hallmark features of the Alzheimer’s disease (AD) brain is the extracellular deposition of amyloid-β protein (Aβ) in both fibrillar (senile plaques) and diffuse forms. Significant proinflammatory markers including activated microglia and cytokines have been detected surrounding the plaques but are absent in diffuse areas suggesting that microglial activation is sensitive to Aβ structure. Since Aβ displays structural polymorphism in vitro, we sought to determine the relationship between Aβ aggregation state and microglial proinflammatory response. Size exclusion chromatography …