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Polylactic Acid-Based Polymer Blends For Durable Applications, Adam Finniss
Polylactic Acid-Based Polymer Blends For Durable Applications, Adam Finniss
Graduate Theses, Dissertations, and Problem Reports
There has been considerable scientific interest in both research and commercial communities as of late in the area of biologically based or sourced plastics. As the consumption of petroleum rises and concerns about climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use PLA more widely, especially in durable applications. Unfortunately, PLA has several drawbacks that hinder more widespread usage of …
Inorganic Nanoparticle Nucleation On Polymer Matrices, Adrian John Kosteleski
Inorganic Nanoparticle Nucleation On Polymer Matrices, Adrian John Kosteleski
Graduate Theses, Dissertations, and Problem Reports
The introduction of inorganic nanoparticles into organic materials enhances both the mechanical and chemical properties of the material. Metallic nanoparticles, like silver and gold, have been introduced into polymers for use as antimicrobial coatings or dielectric materials, respectively. The challenge in creating these materials currently is the difficulty to homogeneously disperse the particles throughout the polymer matrix. The uneven dispersion of nanoparticles can lead to less than optimal quality and undesired properties. By creating a polymer nanocomposite material with well-controlled size inorganic materials that are evenly dispersed throughout the polymer matrix; we can improve the materials performance and properties. The …
Bending And Shear Behavior Of Pultruded Glass Fiber Reinforced Polymer Composite Beams With Closed And Open Sections, Daniel Douglas Estep
Bending And Shear Behavior Of Pultruded Glass Fiber Reinforced Polymer Composite Beams With Closed And Open Sections, Daniel Douglas Estep
Graduate Theses, Dissertations, and Problem Reports
Several advantages, such as high strength-to-weight ratio, high stiffness, superior corrosion resistance, and high fatigue and impact resistance, among others, make FRPs an attractive alternative to conventional construction materials for use in developing new structures as well as rehabilitating in-service infrastructure. As the number of infrastructure applications using FRPs grows, the need for the development of a uniform Load and Resistance Factor Design (LRFD) approach, including design procedures and examples, has become paramount.;Step-by-step design procedures and easy-to-use design formulas are necessary to assure the quality and safety of FRP structural systems by reducing the possibility of design and construction errors. …
Group Iii-Nitride Devices And Applications, Joshua L. Justice
Group Iii-Nitride Devices And Applications, Joshua L. Justice
Graduate Theses, Dissertations, and Problem Reports
The group III-nitride system of materials has had considerable commercial success in recent years in the solid state lighting (SSL) and power electronics markets. The need for high efficient general lighting applications has driven research into InGaN based blue light emitting diodes (LEDs), and demand for more efficient power electronics for telecommunications has driven research into AlGaN based high electron mobility transistors (HEMTs). However, the group III-nitrides material properties make them attractive for several other applications that have not received as much attention. This work focuses on developing group III-nitride based devices for novel applications.;GaN is a robust, chemically inert, …
A Force Sensor Array For Space Applications, Timothy L. Weadon
A Force Sensor Array For Space Applications, Timothy L. Weadon
Graduate Theses, Dissertations, and Problem Reports
The need for force feedback and spatial awareness of contact in harsh environment applications, such as space servicing, has been unsatisfied due to the inability of current sensor technology to resist environmental effects. In this work, capacitive sensors based on a porous polymer-ceramic composite structure were evaluated for potential use in future operations within robotic end-effectors, withstanding temperatures ranging from -80 °C to 120 °C and forces up to 350 kPa. A thin-film design is utilized to allow for ease of embedding, allowing sensors to be implemented into exciting robotic hardware with minimal intrusion, and protecting sensors from electron bombardment, …
Composite Multifunctional Lithium Ion Batteries, Joshua Mullenax
Composite Multifunctional Lithium Ion Batteries, Joshua Mullenax
Graduate Theses, Dissertations, and Problem Reports
The goal of this work was to design a battery that serves as the structural material as well as the power source for a transportation vehicle. The combination of both mechanical and electrochemical aspects within one material defines the component as a multifunctional material, or in this case, a multifunctional battery. The design of the composite multifunctional batteries for optimal performance involves the proper selection of the materials, architecture, and electrical interconnection. The ultimate goal is to incorporate a battery with a continuous composite fibrous fabric within the structured composite skin of a vehicle (such as an automobile or aircraft).;This …
Natural Kenaf Fiber Reinforced Composites As Engineered Structural Materials, David B. Dittenber
Natural Kenaf Fiber Reinforced Composites As Engineered Structural Materials, David B. Dittenber
Graduate Theses, Dissertations, and Problem Reports
The objective of this work was to provide a comprehensive evaluation of natural fiber reinforced polymer (NFRP)'s ability to act as a structural material.;As a chemical treatment, aligned kenaf fibers were treated with sodium hydroxide (alkalization) in different concentrations and durations and then manufactured into kenaf fiber / vinyl ester composite plates. Single fiber tensile properties and composite flexural properties, both in dry and saturated environments, were assessed.;Based on ASTM standard testing, a comparison of flexural, tensile, compressive, and shear mechanical properties was also made between an untreated kenaf fiber reinforced composite, a chemically treated kenaf fiber reinforced composite, a …
Aging Effects Of The Cathode And Determination Of Single Electrode Performance In A Solid Oxide Fuel Cell, Xiaoke Chen
Aging Effects Of The Cathode And Determination Of Single Electrode Performance In A Solid Oxide Fuel Cell, Xiaoke Chen
Graduate Theses, Dissertations, and Problem Reports
Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices due to their advantages of high theoretical efficiency, fuel flexibility (including hydrogen and carbon monoxide), scalability, and low emission. An important problem for commercially using the SOFCs is to improve the long term stability for the SOFCs. To improve the lifetime of SOFCs and develop innovative electrode microstructures; we need to understand the individual process including the degradation processes to the cathode or the anode. To identify the independent anode and cathode contributions to the total impedance, one conventional electrochemical tool for evaluation is the reference electrode. Although reference …
Novel Engineered Nanostructured Complex Oxide For High Temperature Thermoelectric Power Generation, Diego F. Palacio
Novel Engineered Nanostructured Complex Oxide For High Temperature Thermoelectric Power Generation, Diego F. Palacio
Graduate Theses, Dissertations, and Problem Reports
Thermoelectric power generators are a promising technology that can produce electrical power directly from waste heat emitted in energy production and consumption systems. The essential component of thermoelectric generators is the thermoelectric material which performs the energy conversion process. In order to make thermoelectric devices to be considered a significant contributor to US energy infrastructure, it is essential first to foster improvements in high performance thermoelectric materials. They must possess not only a high conversion efficiency, but also need be composed of nontoxic and abundantly available elemental materials having high chemical stability in air up to 800-1000 K. In comparison …
Tribological Analysis Of Hydrophobic Thin Film With Antimicrobial Properties, Elizabeth E. Defusco
Tribological Analysis Of Hydrophobic Thin Film With Antimicrobial Properties, Elizabeth E. Defusco
Graduate Theses, Dissertations, and Problem Reports
Silica based sol gel thin films have become a very popular area of research due to their high degree of variability and ease of manufacturing. They are commonly used as coatings for many applications in the consumer electronics and automotive industries. Some common properties in these thin films include optical transparency, wear resistance, antimicrobial, hydrophobic, electromagnetic, etc.;The coating produced in this research has been tailored to meet three key functions; durability, hydrophobicity, and anti-microbial properties. This coating is created through a three-step sol gel reaction mechanism. The starting chemical, tetraethoxysilane (TEOS), yields the final product of a silicon dioxide matrix. …
A Phase Separation Study Of Biological Polymers In Solid State Films, Jaclyn Nicole Kokx
A Phase Separation Study Of Biological Polymers In Solid State Films, Jaclyn Nicole Kokx
Graduate Theses, Dissertations, and Problem Reports
A growing need for nanoparticle-polymeric composite materials in the electronics and coatings industries has driven research to gain a better understanding of the mechanisms of self-assembled phase separation in polymer thin films and experiment with controlling the phase separation behavior of multicomponent polymer systems. This research proposed that biological polymers have the ability to phase separate into defined structures capable of organizing nanoparticles with unparallel control over the architecture of the molecule compared to synthetic polymers.;This study used recombinant DNA techniques and the expression host E. coli to accurately and repeatedly produce a peptide with a random coil secondary structure. …
Pre And Post Blast Chemical Comparison Of The Intra- And Inter-Variability Of Metal Pipes Commonly Used In Pipe Bombs, Mandi Hellested
Pre And Post Blast Chemical Comparison Of The Intra- And Inter-Variability Of Metal Pipes Commonly Used In Pipe Bombs, Mandi Hellested
Graduate Theses, Dissertations, and Problem Reports
Pipe bombs are a substantial problem around the world killing and injuring thousands each year. Traditionally explosive used, residues of explosives, and bomb components have been the main source of evidence in the investigation of a located or exploded pipe bomb. This research analyzed the trace elemental compositions of metal pipes to investigate if pipes can be compared. It was found that in a sample set of 37 pipes, of different brands and purchase locations, each pipe was homogenous at trace elemental concentrations. This homogeneity allowed for comparison between pipes. An x-ray tube, as an alternate excitation source, which had …
Structural And Mechanical Properties Of Silica And Hybrid Aerogels And Xerogels Studied Using Molecular Dynamics Simulations, John Sandro Rivas Murillo
Structural And Mechanical Properties Of Silica And Hybrid Aerogels And Xerogels Studied Using Molecular Dynamics Simulations, John Sandro Rivas Murillo
Graduate Theses, Dissertations, and Problem Reports
The structural and mechanical properties of silica and hybrid aerogels and xerogels are studied using Molecular Dynamics simulations. Hybrid samples are created by adding methyl groups (CH3) to the silica structure. Silica samples are generated expanding a dense silica glass in a simulation box of volume chosen to produce a porous sample of a specified density. The expanded glass is thermally treated using a combination of heating and cooling processes. The heating process increases the kinetic energy of the atoms in the system, which facilitates their movement throughout the system. The cooling process reduces the kinetic energy of the atoms …
Investigation Of Structural Properties Of Organic Thin Films For Solar Cell And Transistor Applications, Ronak Rahimi
Investigation Of Structural Properties Of Organic Thin Films For Solar Cell And Transistor Applications, Ronak Rahimi
Graduate Theses, Dissertations, and Problem Reports
For the past several decades, organic materials including polymers, oligomers and small molecules have been of great interest for their various applications in the electronics and the semiconductor industry. The most appealing advantages of organic materials compared to their inorganic counterparts are their compatibility with flexible substrates and amenability to low-temperature and low-cost fabrication processes such as evaporation, spin-coating and printing. Moreover, the ability to be utilized in fabrication of lightweight and large-area devices is among other reasons for popularity of organic materials. A large number of studies have reported on various aspects of the development and optimization of organic …
Sol-Gel Derived Wear-Resistant, Hydrophobic, Particle-Reinforced Silica Coatings, Derrick A. Banerjee
Sol-Gel Derived Wear-Resistant, Hydrophobic, Particle-Reinforced Silica Coatings, Derrick A. Banerjee
Graduate Theses, Dissertations, and Problem Reports
Hydrophobic coatings are useful for a wide range of applications including anti-fouling, anti-corrosive, and anti-icing. There are also a number of emerging applications in which transparency is critical such as optoelectronics, touchscreens, and smart windows. For many of these applications, resistance to abrasive wear is also important. Typical low-surface energy coatings such as polytetrafluoroethylene (PTFE) have poor mechanical strength which leaves them susceptible to abrasive wear. To combat this problem, functional moieties can be encapsulated using a sol-gel method to provide improved substrate adhesion and hardness while maintaining transparency and functionality. While this provides an improvement for many applications, the …
Nanostructure And Chemistry Evolution Of Solid Oxide Fuel Cells Upon Cell Operation, Song Chen
Nanostructure And Chemistry Evolution Of Solid Oxide Fuel Cells Upon Cell Operation, Song Chen
Graduate Theses, Dissertations, and Problem Reports
Solid Oxide Fuel Cells (SOFCs) are clean and efficient alternatives to conventional power generation technology. In SOFC, electrochemical reactions take place on the triple-phase boundaries (TPBs) between the electrolyte, the electrode and the gaseous fuel. Small changes in TPB structure or chemistry, and the interface between electrode and electrolyte can drastically affect SOFC performance and lifetime. However, very limited experimental work has been reported on the nanostructure and chemistry evolution of interface and TPBs in the SOFC upon cell operation.;The main goal of this dissertation is to investigate the nanostructure and chemistry of the grain boundaries and interfaces including TPB …
Electronic Structure Of Delafossites For Improved Photocatalysis, M. Kylee Underwood
Electronic Structure Of Delafossites For Improved Photocatalysis, M. Kylee Underwood
Graduate Theses, Dissertations, and Problem Reports
One of the most pressing issues for scientists today is the ever increasing amount of greenhouse gases entering the atmosphere. Carbon dioxide is considered the most prominent greenhouse gas, and emissions from fossil fuel power generation alone represent 26% of global CO2 emissions. Here we computationally examine the properties of a family of materials called delafossites for the photoreduction of CO2 emissions produced through fossil fuel power generation. These materials show promise to reduce CO2 into usable products such as methane through photoelectrochemical reduction. Delafossites are of interest due to the discrepancy between their fundamental and optically measured band gaps. …
Degradation Of Solid Oxide Fuel Cell Anode In Phosphorus-Containing Coal Syngas, Jinlong Yan
Degradation Of Solid Oxide Fuel Cell Anode In Phosphorus-Containing Coal Syngas, Jinlong Yan
Graduate Theses, Dissertations, and Problem Reports
Coal is the dominant energy for electric power generation. Solid oxide fuel cells (SOFCs) has been proposed to be incorporated into the coal based power plant. Currently, Nickel-Yttria stabilized Zirconia (YSZ) composite is widely used as the anode in SOFCs (YSZ as electrolyte) due to its low-cost, high electric conductivity, and excellent catalytic activity for many fuel types. However, the long-term stability of the Ni/YSZ anode remains a major concern when a SOFC is operated using coal syngas. Poisoning by the impurity species in the coal syngas poses severe threat on the SOFCs. Of all the impurities present in coal …
Chirality Sorted Single Walled Carbon Nanotubes For Random Network Thin Film Applications, Volkan Ozyar
Chirality Sorted Single Walled Carbon Nanotubes For Random Network Thin Film Applications, Volkan Ozyar
Graduate Theses, Dissertations, and Problem Reports
Single-walled carbon nanotubes (SWNTs) are comprised entirely of carbon atoms which lie in a graphitic plane rolled into a seamless cylinder. The direction in which the graphic plane is rolled affects the subsequent chiralities of the SWNTs. This direction is called the chiral vector. This chiral vector, Ch =na1+ma2, is described in terms of a pair of integers (n,m) and a pair of lattice vectors (a1,a2) associated with each carbon atom in the graphene sheet. The magnitude of the chiral vector determines the diameter of the nanotubes as d= Ch/pi. SWNTs with integers n-m =3i, where i = 0, 1, …
Synthesis Of Functional 1,2,3-Triazoles And Its Applications In Transition Metal Catalysis, Wuming Yan
Synthesis Of Functional 1,2,3-Triazoles And Its Applications In Transition Metal Catalysis, Wuming Yan
Graduate Theses, Dissertations, and Problem Reports
Several new methodologies for synthesizing functional 1,2,3-triazoles which include arylation, vinylation, propargylation and allenation, have been successfully developed. These resulting new methods are of great benefit to the organic chemists who are working on the research fields related to 1,2,3-triazoles. Particularly, the iron catalyzed propargylation and allenation have initiated the iron chemistry with 1,2,3-triazoles as the ligand. For example, our efforts led to the discovery of a practical approach for the synthesis of conjugated enynes that is challenging through conventional methods. In the synthesis of conjugated enyne, 1,2,3-triazoles were revealed as the only ligand effectively promoting this important and challenging …
Anisotropic Particles: Preparation And Study, Shengrong Ye
Anisotropic Particles: Preparation And Study, Shengrong Ye
Graduate Theses, Dissertations, and Problem Reports
Anisotropic particles have received significant attention in self-assembly for the large scale fabrication of hierarchical structures. Janus particles, a specific class of anisotropic particles, have two hemispheres with different materials. Due to the anisotropic nature of the particle shape and interactions, Janus particles have demonstrated interesting properties in interfacial assembly, switchable devices, cargo transport, and optical sensing. The objective of this research is to fabricate novel anisotropic Janus particles and explore their potential unique properties.;One of the driving forces arises from the previous work of bimetallic nanorods and their autonomous motion. The bimetallic nanorod systems undergo chemically powered non- Brownian …
Immobilized Cytochrome P450 2c9 (Cyp2c9): Applications For Metabolite Generation, Monitoring Protein-Protein Interactions, And Improving In-Vivo Predictions Using Enhanced In-Vitro Models, Lance A. Wollenberg
Immobilized Cytochrome P450 2c9 (Cyp2c9): Applications For Metabolite Generation, Monitoring Protein-Protein Interactions, And Improving In-Vivo Predictions Using Enhanced In-Vitro Models, Lance A. Wollenberg
Graduate Theses, Dissertations, and Problem Reports
Cytochrome P450 (P450) enzymes are a family of oxoferroreductase enzymes containing a heme moiety and are well known to be involved in the metabolism of a wide variety of endogenous and xenobiotic materials. It is estimated that roughly 75% of all pharmaceutical compounds are metabolized by these enzymes. Traditional reconstituted in-vitro incubation studies using recombinant P450 enzymes are often used to predict in-vivo kinetic parameters of a drug early in development. However, in many cases, these reconstituted incubations are prone to aggregation which has been shown to affect the catalytic activity of an enzyme. Moreover, the presence of other isoforms …
Molecular Beam Epitaxy Of Multiferroic Ymno3 On C-Plane Gan, Cameron Keenan
Molecular Beam Epitaxy Of Multiferroic Ymno3 On C-Plane Gan, Cameron Keenan
Graduate Theses, Dissertations, and Problem Reports
YMnO3 is a hexagonal ferroelectric which has gained significant interest for its potential use in metal--ferroelectric-semiconductor and metal-ferroelectricmetal device structures as a means to replace currently used materials containing toxic elements, such as lead. Low coercive field and dielectric constant are just two of the advantageous properties that make this material attractive for device use, but retention and large leakage effects have become impediments to device implementation. YMnO3 is also a multiferroic material at low temperatures (below ∼77 K) and can therefore be studied to determine the feasibility of ferroelectric-magnetic coupled control of electronic devices.;In this study, YMnO3 was deposited …
Nanosize Effects In The Magnetic Properties Of The Two Layered Hydroxides Of Nickel, James D. Rall
Nanosize Effects In The Magnetic Properties Of The Two Layered Hydroxides Of Nickel, James D. Rall
Graduate Theses, Dissertations, and Problem Reports
Investigations of properties of materials with lower lattice dimensionality (one and two dimensions) often provides good opportunity to advance physics since solutions to corresponding theoretical models are more easily obtained. In this work, results on magnetic properties of two quasi two-dimensional (2D) systems viz. the layered hydroxides of nickel, beta-Ni(OH)2 and alpha-Ni(OH)2, are reported. For beta-Ni(OH)2, there have been conflicting reports in the literature whether the magnetic ordering is ferromagnetic or antiferromagnetic. For the less stable alpha-Ni(OH) 2 with the larger spacing between the layers, the nature of magnetism is largely unexplained. Therefore, the results and their interpretation present here …
Prediction Of Mechanical Properties Of Aerogels Using A Multifractal Multidimensional Multiscaling Approach, Fritz Andres Campo Schickler
Prediction Of Mechanical Properties Of Aerogels Using A Multifractal Multidimensional Multiscaling Approach, Fritz Andres Campo Schickler
Graduate Theses, Dissertations, and Problem Reports
Aerogels, produced by sol-gel technologies, have several applications in sensors, high energy particle physics, catalysis, heat insulation, supercapacitors, heat storage devices, high efficiency windows, among others. These applications take advantage of the outstanding properties these materials present as a result of their structure. However, the low mechanical properties that these materials present as result of the process, limits their commercial applications. In this dissertation, it is investigated the relationship between the processing conditions and mechanical properties of these materials computationally.;The prediction of the effective properties for these materials is a daunting task because of their complex structure. Aerogels's structure is …
Structural Responses And Finite Element Modeling Of Hakka Tulou Rammed Earth Structures, Daniel Sranislawski
Structural Responses And Finite Element Modeling Of Hakka Tulou Rammed Earth Structures, Daniel Sranislawski
Graduate Theses, Dissertations, and Problem Reports
Hakka Tulous are rammed earth structures that have survived the effects of aging and natural elements upwards of even over a thousand years. These structures have housed the Hakka people of the Fujian Province, China in natural yet modern housing that has provided benefits over newer building materials. The key building material, rammed earth, which is used for the walls of the Hakka Tulou structures, has provided structural stability along with thermal comfort to the respective inhabitants of the Hakka Tulous.;Through material testing and analysis this study has examined how the Tulou structures have maintained their structural stability while also …
Functionalization Of Buckled Graphene, Timothy C. Nelson
Functionalization Of Buckled Graphene, Timothy C. Nelson
Graduate Theses, Dissertations, and Problem Reports
Buckled graphene produced by the halogen based etching of 6H-SiC provides a new route for the functionalization of the graphene surface. This surface provides an important new stepping off point in the development of molecular electronics and sensors. While the graphene surface is relatively inert, the fluorinated defect sites inherent in the buckled graphene surface yield an excellent location for chemical reactions such as nucleophilic substitution. This thesis shows the utility of the fluorinated defect sites through the well characterized diazonium reaction.;Buckled graphene films were prepared on silicon carbide substrates using inductively coupled plasma and reactive ion etching, and annealed …
Cluster Growth During De-Wetting Of Solid Thin Films: Coarsening Exponents And The Role Of Long Range De-Wetting Interactions, Adi Constantinescu
Cluster Growth During De-Wetting Of Solid Thin Films: Coarsening Exponents And The Role Of Long Range De-Wetting Interactions, Adi Constantinescu
Graduate Theses, Dissertations, and Problem Reports
Coarsening processes play prominent roles in non-equilibrium statistical physics and in applied physical sciences. A new area in this field of statistical physics has emerged from recent experimental revelations that long range de-wetting forces acting across thin films, such as the fundamental van der Waals interactions, may drive the formation of large clusters (tall multi-layer islands) and pits, observed in thin films of soft materials (polymers), as well as in thin films of liquid and solid metals. Motivated by the experiments, in this Thesis we elucidate the fundamentals of the non-equilibrium statistical mechanics of solid thin films coarsening within a …
Microstructural Control And Characterization Of Bi2v0.9cu0.1o5.35 (Bicuvox) Ceramics, Soheil Razmyar
Microstructural Control And Characterization Of Bi2v0.9cu0.1o5.35 (Bicuvox) Ceramics, Soheil Razmyar
Graduate Theses, Dissertations, and Problem Reports
The widespread commercialization of solid-oxide fuel cells (SOFCs) and solid-oxide electrolyte cells (SOECs) is primarily limited by material degradation issues related to the required high temperature operation (>800°C). Applications of stabilized zirconia based electrolytes, which are the most commonly used oxide ion conductors, have been limited to this high temperature regime due to its low oxygen ion conductivity below 800°C. Solid electrolytes made of the BIMEVOX compositional family of materials (Bi2MexV 1-xO5.5-delta where Me=Cu, Co, Mg, Ni, Fe...) exhibit high oxide ionic conductivity similar to YSZ at a low temperature (300--600°C). Among these materials copper-substituted bismuth vanadate (Bi2V0.9Cu0.1O5.35, BICUVOX), …
Leaching Of Chalcopyrite With Sodium Hypochlorite, Ravinder Kumar Garlapalli
Leaching Of Chalcopyrite With Sodium Hypochlorite, Ravinder Kumar Garlapalli
Graduate Theses, Dissertations, and Problem Reports
Chalcopyrite is the most important copper mineral source and also a refractory mineral for leaching. Several processing routes have been proposed to overcome the environmental problems related to copper extraction from chalcopyrite. In this study, the leaching of chalcopyrite has been investigated with a new reagent sodium hypochlorite (NaOCl). Experiments were carried out in two stages: conversion of chalcopyrite to cupric oxide with NaOCl solution in the first stage, followed by dissolution of the cupric oxide to cupric ion with 1 normal sulfuric acid at room temperature in the second stage. In the first stage leaching, the initial pH varied …