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Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra

LSU Doctoral Dissertations

Rare earth-transition metal alloys are of interest in MEMS and magnetic storage industries because of their unique magnetic properties. However, the applications of these alloys have been limited to bulk and thin film architectures because of the limitations of the contemporary vapor deposition technique to fabricate high aspect ratio nanostructures. The objective of this study is to develop an electrochemical process to deposit rare earth-transition metal alloys thus making it possible to deposit high aspect ratio nanostructures such as nanowires and nanotubes, which helps to tune their properties for specific applications. Electrodeposition of rare earth-transition metal alloys was achieved from …

Granular Contact Lubrication: Theory And Experiment, Karim El Kholy

LSU Doctoral Dissertations

This dissertation is devoted to a theoretical and experimental study of the granular contact lubrication, both. The theory is based on the kinetic of the granular material where the granules interact with each other and with the boundary surfaces through instantaneous, binary collisions, characterized by a constant coefficient of restitution. Specifically this study focuses on granular lubrication in Couette flows. A series of simulations is reported and the results show good agreement with several published papers. Also, a theory that ties the true temperature to the grain mobility is developed. The true temperature of a granular material depends on the …

Copper(Ii) Oxide Mediated Formation And Stabilization Of Combustion Generated Persistent Free Radicals, Hieu Truong

LSU Doctoral Dissertations

Biologically damaging semiquinone-type radicals have been reported in cigarette smoke, their likely origin being hydroquinone (HQ) and catechol (CT) molecular precursors contained by the tobacco. Since other biomass contains HQ and CT-type species, it is likely that combustion of other biomass will also form semiquinone-type radicals. All hydrocarbon fuels will form phenol and substituted phenol that can form substituted phenoxyl radicals. Because each of these radicals has the potential to be environmentally persistent and biologically active, their formation and stabilization from various molecular precursors was studied with the focus on surface-bound radicals formed in association with combustion-generated fly-ash particles. Comprehensive …

Effects Of Cryopreservation And Constituents Of Semen Extenders On Mitochondrial Function Of Bull Spermatozoa, Abdulhakeem Hashim Eljarah

LSU Doctoral Dissertations

This study investigated the effects of semen extender constituents and cryopreservation on bovine spermatozoal mitochondrial function. Three yearling Holstein bulls were used. Two ejaculates per bull were collected and pooled on a weekly basis for five weeks and extended in four treatments: 1) sodium citrate egg yolk extender with antibiotics (lincomycin, spectinomycin, gentamicin and tylosin); 2) ¡°1¡± with glycerol; 3) ¡°2¡± without antibiotics; and 4) ¡°1¡± without antibiotics. Each was divided into portions for analyses before freezing and after cryopreservation. The pre-freeze and thawed semen were transferred to a 37¡ãC water bath, the same assays were performed. In experiment 1, …

Particle And Dredge-Scale Kinetic Studies Of Hydrophobic Organic Chemical Desorption From Sediment, Justin Edward Birdwell

LSU Doctoral Dissertations

The discharge of hydrophobic organic chemicals (HOCs) and other hazardous substances from anthropogenic sources to surface waters and the atmosphere has led to the widespread contamination of bottom sediments throughout the world. HOCs collect in sediments due to their affinity for organic matter and other sorbents present on and within their solid matrices. There is interest in the movement of HOCs from historically contaminated, resuspended sediments to surface waters due to the connection between chemical desorption and bioavailability. Quantitatively accurate predictions of contaminant concentrations in environmental media are needed for reliable risk assessment and to develop strategies for protection of …

The Urban Development Of Spanish Colonial Pensacola, 1781-1821, Harry James Wilson

LSU Doctoral Dissertations

Pensacola evolved through the second Spanish period (1781-1821) from a fledgling military outpost to an increasingly complex urban center. Local and regional demographic trends and environmental conditions prompted Pensacola to grow in a manner that differed from other Spanish colonial urban centers and created in Pensacola an unusual class structure and residential patterning. The primary goal of this dissertation is to show that Pensacola’s residential and landowning patterns never experienced the degree of socioeconomic residential clustering noted in other Spanish colonial urban centers. Social residential clustering was unusual in Spanish Pensacola, and socioeconomic classes and land values varied from lot …

Characterization Of Advanced Composites- A Nondestructive Approach, Phani Surya Kiran Mylavarapu

LSU Doctoral Dissertations

Adhesively bonded sandwich structures comprising of particulate composites as core and graphite epoxy skins as stiffeners are widely used for various applications in the marine and aerospace industry. The core material and the stiffener are held together by an adhesive bond. Particulate composites are made from a mixture of a polymer resin and hollow or solid particles. Hollow particulate composites are known as syntactic foams. Particulate composites possess attractive mechanical and physical properties such as high compressive strength etc, making them attractive materials for use in structural applications. Characterization of the adhesive bondline and core material in sandwich structures is …

Hope For Today And Tomorrow: Identity Construction Power, And Persistence Of Community College Women Who Are First In Their Families To Attend College, Crystal Deer Lee

LSU Doctoral Dissertations

This dissertation was a case study of four community college women who were first in their families to attend college. Through this study, the “first-generation” construct was analyzed in regard to its uses and limits. The researcher found the label as an identifier becomes problematic through social discourse. These results confirm London’s (1996) finding that students themselves do not necessarily find anything unique about their situations or anything in common with other students simply based on their being the first in their families to attend college. Therefore, the “first-generation” construct may be viewed primarily as a higher education versus an …

Quintet For Two Violins, Viola, Cello And Piano, And String Quartet No. 1 By Lazar Nikolov, Alexandra Dotcheva

LSU Doctoral Dissertations

Lazar Nikolov (1922-2005) was a representative of the so-called third generation of Bulgarian composers. Together with his closest friend, composer and conductor Konstantin Iliev, Nikolov founded the postwar avant garde in Bulgaria. He was among the first composers in Eastern Europe to abandon the influence of musical folklore and employ non-tonal techniques. Shortly before graduating from the State Academy of Music in 1946, Nikolov felt that the masters from the previous two generations had already used all the successful means to incorporate neo-Romantic features and Bulgarian folk material into art music. He was perceptive enough to recognize the danger of …

A Comparison Of Channel Morphology, Marsh Elevation, And Biological Processes In Natural And Dredged Tidal Salt Marshes In Louisiana, Jennifer S. Spicer

LSU Doctoral Dissertations

Channel networks in tidal marshes serve as conduits for the exchange of water between the estuary and the marsh surface and form the spatial structure that regulates the flow of organisms, materials, and energy throughout the marsh system. Canal dredging creates channels with distinct linear shapes, and the artificial levee created from the dredged material creates ‘spoil banks’ along either side of the channel edge. Differences in morphology and adjacent marsh surface elevation between natural and dredged channel systems have not been well quantified, but may have important implications for the functioning of tidal channels as habitat for marsh-dependent species. …

Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin

LSU Doctoral Dissertations

This work involves developing processing techniques for monolithically integrating a high-aspect-ratio microstructures with CMOS circuitry. A microsystem comprising of a microprobe array and signal processing circuitry is utilized as a test vehicle to demonstrate this fabrication process. One potential application of this microsystem is for recording neural signals from the central nervous system. The main results include thick photoresist processing, DC and pulse electroplating to form high-aspect-ratio microprobes, microprobe sharpening and developing a post-IC monolithic integration process. SU-8 is utilized for thick photoresist application. This work focuses on realization of a deep microrecess array in thick resists rather than traditional …

An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri

LSU Doctoral Dissertations

This research deals with an experimental and numerical investigation of the frictional and thermal behavior of pin-bushing pairs, operating at reciprocating sliding motion or under heavy loads. Large interfacial temperatures developed due to frictional heating can cause failure. Therefore, numerical prediction and analysis of the surface temperature under various operating conditions are important. Laboratory tests using a pin-bushing tester provided measurements of the friction coefficient and temperature. Hard coated and plain (uncoated) bushings, both made of induction hardened stainless steel, were tested. Lower coefficient of friction and surface temperature were observed in the case of the coated bushing. In the …

Modeling Spatial And Temporal Variations Of Surface Moisture Content And Groundwater Table Fluctuations On A Fine-Grained Beach, Padre Island, Texas, Yuanda Zhu

LSU Doctoral Dissertations

The basic goals of this study are to document, represent and model beach surface moisture dynamics. Achieving these goals requires that the dynamics be understood within the context of the key associated processes including evaporation and groundwater table fluctuations. Atmospheric parameters including wind speed, air temperature and relative humidity, evaporation, beach surface moisture content, groundwater table fluctuations and tidal oscillations were directly monitored in an eight-day field experiment. Field measurements demonstrated that beach surface moisture content has a relatively high degree of variability in the cross-shore direction and a relatively low variability in the alongshore direction. The highest levels of …

Shear Responses Of Poly(Ethylene Oxide)-Laponite Nanocomposite Hydrogels, Elena Loizou

LSU Doctoral Dissertations

This research seeks to understand the structure and shear responses of poly(ethylene oxide)-Laponite nanocomposite hydrogels and to relate the macroscopic physical properties to the nanoscopic structural changes. Understanding that relationship is necessary, in order to tailor material properties to specific applications. Information on the structure at rest on multiple length scales was obtained by combining microscopic and neutron scattering techniques. The structural changes that occur in response to a shear field were explored using rheology and neutron scattering. These structures were examined as a function of polymer molecular weight, polymer and clay concentrations, and sample preparation method. While the sample …

Structural Manipulation Of Pyrrole-Terminated Dendrimers To Create A More Efficient Encapsulation/Release System, Henry Wiggins

LSU Doctoral Dissertations

This work demonstrates the ability to manipulate the structure of pyrrole-terminated dendrimers by modifying solution conditions which directly affects their encapsulation properties. Investigations were conducted using FTIR and 2D NMR to determine the location of end groups. NMR relaxation studies were conducted at various temperatures and different solution pH to gain an understanding of the relative mobility and rigidity of different areas of the dendrimer. It was found that that the release properties were affected by the solution pH and the presence of salt. Further the effectiveness of retaining molecular guests by oligo-pyrrole terminated dendrimers with a range of oligomer …

Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani

LSU Doctoral Dissertations

Mechanistic modeling of an underbalanced drilling operation using carbon dioxide has been developed in this research. The use of carbon dioxide in an underbalanced drilling operation eliminates some of the operational difficulties that arises with gaseous drilling fluids, such as generating enough torque to run a downhole motor. The unique properties of CO₂, both inside the drill pipe and in the annulus are shown in terms of optimizing the drilling operation by achieving a low bottomhole pressure window. Typically CO₂ becomes supercritical inside the drill pipe at this high density; it will generate enough torque to run …

Simulations-Guided Design Of Process Analytical Sensor Using Molecular Factor Computing, Bin Dai

University of Kentucky Doctoral Dissertations

Many areas of science now generate huge volumes of data that present visualization, modeling, and interpretation challenges. Methods for effectively representing the original data in a reduced coordinate space are therefore receiving much attention. The purpose of this research is to test the hypothesis that molecular computing of vectors for transformation matrices enables spectra to be represented in any arbitrary coordinate system. New coordinate systems are selected to reduce the dimensionality of the spectral hyperspace and simplify the mechanical/electrical/computational construction of a spectrometer. A novel integrated sensing and processing system, termed Molecular Factor Computing (MFC) based near infrared (NIR) spectrometer, …

Integrated Approach To The Superplastic Forming Of Magnesium Alloys, Fadi K. Abu-Farha

University of Kentucky Doctoral Dissertations

The economical and environmental issues associated with fossil fuels have been urging the automotive industry to cut the fuel consumption and exhaust emission levels, mainly by reducing the weight of vehicles. However, customers increasing demands for safer, more powerful and luxurious vehicles have been adding more weight to the various categories of vehicles, even the smallest ones. Leading car manufacturers have shown that significant weight reduction, yet satisfying the growing demands of customers, would not be feasible without the extensive use of lightweight materials. Magnesium is the lightest constructional metal on earth, offering a great potential for weight-savings. However, magnesium …

Computer Simulation And Modeling Of Physical And Biological Processes Using Partial Differential Equations, Wensheng Shen

University of Kentucky Doctoral Dissertations

Scientific research in areas of physics, chemistry, and biology traditionally depends purely on experimental and theoretical methods. Recently numerical simulation is emerging as the third way of science discovery beyond the experimental and theoretical approaches. This work describes some general procedures in numerical computation, and presents several applications of numerical modeling in bioheat transfer and biomechanics, jet diffusion flame, and bio-molecular interactions of proteins in blood circulation.

A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to external heating. The temperature distribution of the skin is …

Virtual' Brides In The Post-Soviet Context, Michael Paul Begin

University of Kentucky Doctoral Dissertations

This project offers a multifaceted, interdisciplinary approach to understanding the contemporary post-Soviet Internet bride phenomenon and the rationales, motives, and aspirations of the industry's participants. As international marriage services have incorporated information and communications technologies (ICTs) to assist in the marketing of women of post-communist nations for correspondence courtship with Western men, the industry has furthered the globalization of marriage markets and the opportunities for communicative exchange among disparate nations and cultures. By way of case study, the project takes a special focus on the Belarusian/American segment of the industry, turning to personal interviews with participants and employing qualitative techniques …

Diversity In A Japanese Transplant: The Effect Of Gender, Race, Age, And Employment Status On Teamwork, Elena Darina Lepadatu

University of Kentucky Doctoral Dissertations

Diversity and Teamwork are currently some of the trendiest human resources strategies of boosting team performance and ultimately, organizational performance. This study analyzes the impact of gender, racial, age and employment status diversity on teamwork, and is one of the first studies on diversity and teamwork in the mature phase of Japanese transplants. The theoretical framework includes elements of the symbolic interactionist theory, Kanter.s theory on tokenism, revised contact hypothesis and perspectives on cultural diversity (Ely and Thomas, 2001). The data were collected from interviews with 87 workers from 16 production teams working on the assembly line at a top …

Automated High-Speed Monitoring Of Metal Transfer For Real-Time Control, Zhenzhou Wang

University of Kentucky Doctoral Dissertations

In the novel Double Electrode Gas Metal Arc Welding (DE-GMAW), the transfer of the liquid metal from the wire to the work-piece determines the weld quality and for applications where the precision is critical, the metal transfer process needs to be monitored and controlled to control the diameter, trajectory, and transfer rate of the droplet of liquid metal. In this doctoral research work, the traditional methods of tracking, Correlation, Least Square Matching (LSM) and Kalman Filtering (KF), are tried first. All of them failed due to the poor quality of the metal transfer image and the variety of the droplet. …

Functionalization Of Fluorinated Surfactant Templated Silica, Gifty Osei-Prempeh

University of Kentucky Doctoral Dissertations

Surfactant templating provides for the synthesis of ordered mesoporous silica and the opportunity to tailor the pore size, pore structure, particle morphology and surface functionality of the silica through the selection of synthesis conditions and surfactant template. This work extends the synthesis of nanostructured silica using fluorinated surfactant templates to the synthesis of organic/inorganic composites. The effect of fluorinated surfactant templates (C6F13C2H4NC5H5Cl, C8F17C2H4NC5H5Cl and C10F21C2H4NC5H5Cl), which have highly hydrophobic fluorocarbon tails, on functional group incorporation, accessibility, and silica textural properties is examined and compared to properties of hydrocarbon surfactant (C16H33N(CH3)3Br, CTAB) templated silica. Hydrocarbon (vinyl, n-decyl and 3-aminopropyl) and fluorocarbon …

Characterization And Flow Physics Of Plasma Synthetic Jet Actuators, Arvind Santhanakrishnan

University of Kentucky Doctoral Dissertations

Plasma synthetic jet actuators are investigated experimentally, in which the geometrical design of single dielectric barrier discharge (SDBD) plasma actuators is modified to produce zero-mass flux jets similar to those created by mechanical devices. The SDBD plasma actuator consists of two rectangular electrodes oriented asymmetrically and separated by a layer of dielectric material. Under an input of high voltage, high frequency AC or pulsed DC, a region of plasma is created in the interfacial air gap on account of electrical breakdown of the ambient air. A coupling between the electric field in the plasma and the neutral air near the …

Gmres On A Tridiagonal Toeplitz Linear System, Wei Zhang

University of Kentucky Doctoral Dissertations

The Generalized Minimal Residual method (GMRES) is often used to solve a nonsymmetric linear system Ax = b. But its convergence analysis is a rather difficult task in general. A commonly used approach is to diagonalize A = XΛX-1 and then separate the study of GMRES convergence behavior into optimizing the condition number of X and a polynomial minimization problem over As spectrum. This artificial separation could greatly overestimate GMRES residuals and likely yields error bounds that are too far from the actual ones. On the other hand, considering the effects of both As spectrum and the conditioning of X …

Pore Engineering Of Surfactant Templated Nanoporous Silica Using Supercritical Carbon Dioxide, Kaustav Ghosh

University of Kentucky Doctoral Dissertations

The use of compressed CO2 processing to alter the pore size, structure and timescale of silica condensation in surfactant templated silica thin films and powders is investigated by systematically varying the template structure and CO2 processing conditions. Tailoring the mesoporous materials increases its potential applications, as demonstrated in catalysis, drug delivery, chromatographic and electrode applications. This work demonstrates for the first time the applicability of fluorinated surfactants as templates for the synthesis of mesoporous silica thin films by dip coating. Well-ordered films with 2D hexagonal close-packed pore structure are synthesized in an acid-catalyzed medium using three cationic fluorinated templates of …

Characterization Of Colloidal Nanoparticle Aggregates Using Light Scattering Techniques, Mehmet Kozan

University of Kentucky Doctoral Dissertations

Light scattering is a powerful characterization tool for determining shape, size, and size distribution of fine particles, as well as complex, irregular structures of their aggregates. Small angle static light scattering and elliptically polarized light scattering techniques produce accurate results and provide real time, non-intrusive, and in-situ observations on prevailing process conditions in three-dimensional systems. As such, they complement conventional characterization tools such as SEM and TEM which have their known disadvantages and limitations. In this study, we provide a thorough light scattering analysis of colloidal tungsten trioxide (WO3) nanoparticles in the shape of irregular nanospheres and cylindrical nanowires, and …

Capacitance Metrology Of Curved Surfaces: Study And Characterization Of A Novel Probe Design, Philip T. Smith Jr.

University of Kentucky Doctoral Dissertations

Capacitive sensors are frequently applied to curved target surfaces for precision displacement measurements. In most cases, these sensors have not been recalibrated to take the curvature of the target into consideration. This recalibration becomes more critical as the target surface becomes smaller in comparison to the sensor. Calibration data are presented for a variety of capacitance probe sizes with widely varying geometries. One target surface particularly difficult to characterize is the inner surface of small holes, less than one millimeter in diameter. Although contact probes can successfully measure the inner surface of a hole, these probes are often fragile and …

Controlled Release Of Osteotropic Molecules Stimulates In Vitro Cellular Activity And In Vivo Local Bone Regeneration, Ju Hyeong Jeon

University of Kentucky Doctoral Dissertations

Bone defects treatment and reconstructive surgery continues to increase at a significant rate. Current bone defect treatments are autotransplantation, allograft, and xenografts create many problems such as, inflammation, infection and chronic pain. Moreover, allografts and xenografts arouse immune rejection. These problems have led to development of controlled release system for use as alternatives to autografts, allografts and xenografts in bone repair. There have been many approaches for sustained drug delivery in local bone regeneration using biodegradable polymers and osteotropic biomolecules. This dissertation presents new approaches that apply intermittent drug delivery for local bone regeneration. In the first, the osteotropic molecules …

Enhanced Fire Retardancy Of Vinyl Ester Resins By Combination Of Additives, Grace Chigwada, Charles A. Wilkie

Chemistry Faculty Research and Publications

In pursuit of fire-retardant materials, vinyl ester resins were combined with commercially available fire retardants at lower loadings than that at which they are usually effective when used alone. The thermal stability and flammability of the various combinations of fire retardants were evaluated by thermogravimetric analysis and cone calorimetric analysis. With some combinations, the 50% degradation temperature was improved by about 5-10ºC Different additives affected the flammability to varying extents and some combinations resulted in an enhanced fire retardancy compared to the additives used alone. The combinations that showed the best reductions in the peak heat release rate (PHRR) were …