Fabrication and synthesis of nanostructured materials are essential aspects of nanoscience and nanotechnology. Although researchers are now able to create and tailor different nanostructured materials, the ability to precisely control the materials' sizes, shapes, and properties at the nanoscale level remains challenging. The aim of this dissertation was to develop new methods to aid researchers in overcoming these challenges. The study investigated two different methods used to create one-dimensional carbon nanostructures, i.e. carbon nanotubes and carbon nanopillars.In the first section, chemical vapor deposition method was used to grow carbon nanotubes (CNTs). Studies examining the effects of methane and hydrogen flow rates on the growth of CNTs were conducted. Results indicated that multi-walled CNTs with metallic properties could be obtained at a methane flow rates as low as 300 cc/min. At higher methane flow rates, i.e. 600-700 cc/min, semiconducting single-walled CNTs and double-walled CNTs were produced. Another phase of this section developed a new and simple CNT growth method using a solid carbon source and indicated polyacrylonitrile and nanosized SiO₂ were effective in producing MWCNTs. In the second part, a new nanoimprint technique was developed to enable printing of nanostructures at sub-100nm level using various polymers. This technique inherited its high-resolution feature from traditional nanoimprint lithography, but without the use of pressure. To demonstrate, PAN nanopillar structures were printed and converted to carbon. In another phase of the part, the use of our imprint technique resulted in the creation and conversion of polysilazane nanostructures to ceramic for the first time.The final section of this dissertation is devoted to study the impact of porosity in gas diffusion layers (GDLs) on the performance of fuel cells. In one study, a new technique using SEM images to determine GDL porosity was developed. The difference between SEM calculated porosities and mercury intrusion porosimetry measurements were less than 2%. The second study characterized fuel cell performances using GDLs constructed with additional micro porous layers (MPLs) and treated with different wet proofing treatments (WPT). Results showed that when MPL is added, cell performance decreases. However, the increase in WPT in the MPL improved cell performance.

The first part of this dissertation focuses on self-assembled composites. Self-assembled composites composed of vertically aligned multiwalled carbon nanofibers (VA-MWCNF) combined with a graphitic layer (GL) arranged perpendicular to MWCNF axes‘ have been produced at low temperature (445 °C) using low pressure thermal chemical vapor deposition (LPCVD). Electron microscopy and Raman spectroscopy were used to analyze composite morphology, structure and quality. It is found that different composite morphologies and modification of the GL structure can be obtained by varying the nickel (Ni) catalyst underlayer materials, the catalyst pre-treatment method, the gas recipe, the gas flow rates and the pressure conditions of the LPCVD process. Pre-treatment of the catalyst with H2 plasma or NH₃ gas was also investigated. It is found that even a short, one minute H2 plasma pre-treatment of the catalyst results in a significant break-down of the VA-MWCNF/GL composite structure. On the other hand, a one or ten minute catalyst pre-treatment with NH₃ gas results in a structural modification of the GL but retains the VA-MWCNF/GL composite structure. An increase in time of NH₃ gas pre-treatment leads to reduced VA-MWCNF/GL composite height. A growth mechanism for VA-MWCNF/GL composites was proposed. The focus, of the second part of this dissertation, is on the analysis of natural chalks used in traditional old master drawings. Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis were performed on bulk samples of natural black chalk, steatite and calcite natural white chalks and on samples of these chalks applied to paper using various techniques. Critical information was obtained about the morphology and sub-micron features of the chalk particles, the chalk/paper interaction of each application technique and elemental composition of the bulk chalk samples. It was found that the particle size and morphology of the natural white chalks reduced their ability to hold to the paper. This information provides insight as to why black chalk is more resistant to abrasion than the natural white chalks which is important for the conservation of extant chalk drawings.

This study aimed to propose and test an integrated model of information processing and dual-processing components (IP-DP model) to explain connections among delinquency-related factors and treatment engagement. Hypotheses stated that exposure to aggressive friends would be associated with maladaptive cognitive scripts, and maladaptive scripts would mediate relationships between exposure and delinquency, and exposure and engagement. Analytic thinking was expected to moderate these relationships by attenuating the negative effects of exposure and maladaptive scripts on outcome measures. Data were collected from 424 adolescents in 8 community-based residential treatment facilities as a part of the TCU Adolescent Project. Hypotheses were tested using PROC MIANALYZE to conduct multiple regression across 5 imputed datasets. Results indicated that maladaptive scripts partially mediate the relationships between exposure and hostility, and exposure and negative urgency. Analytic thinking moderates the relationships between maladaptive scripts and engagement. Findings were not supportive of the IP-DP model but suggest further testing.

Large numbers of migratory tree bats are being killed at wind energy facilities across North America, and this rapidly growing source of renewable energy may pose a threat to bat populations. In 2012 and 2013 we conducted an ultrasound playback experiment, night vision surveys, and acoustic monitoring to determine if bats could be attracted to the smooth wind turbines surfaces because they perceive them to be water. Our playback experiment revealed little or no differences in the physical characteristics of echoes reflected from water and turbine surfaces. Our video and acoustic surveys indicated that bats behave at wind turbines as they do around water sources. Moreover, we observed bats attempting to drink from turbine towers at rates similar to water sources. Our data suggest that bats may be attracted to wind turbines because the surfaces produce an acoustic signature that is indistinguishable from water.

Mucus secretion is the first-line of defence against the barrage of irritants inhaled into human lungs, but abnormally thick and viscous mucus results in many respiratory diseases. Investigation of processes underlying mucus pathology is hampered, in part, by lack of appropriate experimental tools for labeling and studying mucin granule secretion from live cells with high sensitivity and temporal resolution. Fluorescence spectra and fluorescence lifetime of AO measurements reveal significant changes due to aggregation, and this properties can be useful for determination of mucus expansion. In this report I present original spectroscopic properties of acridine orange (AO) which could be utilized to study granule release and mucin swelling with novel fluorescence imaging approaches. To explore fluorescent properties we measured the quantum yield and extinction coefficient and lifetimes.

Enon is an anomalous stony-iron meteorite having an affinity to both achondrites and ordinary chondrites. This study uses mineral chemistry, oxygen isotopes, and two-pyroxene geothermometry to understand Enon's formation history and to determine if it can be genetically related to any other known meteorite group. SEM mineral maps were used to identify texture and mineralogy, and detailed chemical analyses were obtained by electron microprobe. Oxygen isotope data was collected by analyzing powered olivine by infrared laser-assisted fluorination. The program QUILF was used to calculate the two-pyroxene closure temperature for Enon. Results indicate that Enon has approximately chondritic silicate compositions; an oxygen isotope composition similar to mesosiderites/HEDs; and experienced partial melting at the Fe, Ni-FeS eutectic and silicate recrystallization and major-element equilibration. This study suggests that Enon is a primitive achondrite that records the onset of igneous differentiation of its parent body.

Hepatitis C Virus (HCV) is a human liver pathogen. In the host its infection leads to acute and chronic hepatitis, cirrhosis and hepatocellular carcinoma. This positive stranded RNA virus is extremely efficient in establishing persistent infection by escaping immune detection by hindering the host immune responses. An important component of the host’s innate immune response in viral infection is the production of type I interferons (IFNs). Typically, viral infection induces the synthesis and secretion of interferon α/β (IFN α/β) by the infected cell, which in turn activates signaling pathways leading to the establishment of an antiviral state in the cell. This raises the question of how HCV circumvents the antiviral immune responses of host cells. Previous studies have shown that HCV nonstructural protein NS3/4A interferes with the activation of signaling pathways that leads to the activation of the IFNβ. Our lab has identified another HCV protein, NS5A, that also interferes with host antiviral signaling independent of the NS3/4A-mediated inhibition of the host antiviral response. Activation of IFNβ gene expression involves the activation of three transcription factors (ATF-2, IRF3/7 and NF-κB) and the formation of an enhanceosome on the promoter. To investigate the influence of HCV NS5A on innate immunity, we study the effect of NS5A over-expression on Sendai Virus (SV)-mediated IFNβ gene induction via qPCR and reporter gene assay. We have identified NS5A to be a potent inhibitor of the host innate immune system, possibly through inhibition of IRF3 activation. We are currently investigating the effect of NS5A on transcription factor activation. NS5A inhibition of IFNβ induction, may be another factor contributing to the persistence of HCV in the host, and may play a key role in designing therapies for the treatment of HCV infection.

Abstract: IMPACT OF NUCLEAR-MITOCHONDRIAL HYBRIDIZATION ON FITNESS AND OXIDATIVE STRESS IN CAENORHABDITIS BRIGGSAE AND C. SP. 9 Mason John Yockey MS 2013 Department of Biology, Texas Christian University Dr. Phil Hartman, Professor, Dean of College of Science & Engineering Mitochondria are organelles contained in eukaryotic cells, which produce energy. Mitochondria are unique for several reasons, one being that they contain a small genome of their own, distinct from the main genome contained within the nucleus. Proper co-ordination between the nucleus and the mitochondria is vital for the functioning of the cell. A study was recently performed on several hybrid strains of Caenorhabditis nematodes which contained nuclear DNA from one lineage and mitochondrial DNA from another. Their fitness was tested by examining their growth, reproduction, lifespan under oxidative stress in the form of 95% oxygen. Results from these experiments appeared to show these trends: growth was typically suppressed, reproduction diminished, and lifespan slightly extended by the oxygen stress. These results might indicate the presence of a mitochondrial hormetic effect in these organisms.

Corrosion is a major issue in applications involving materials in normal and severe environments, especially when it involves corrosive fluids, high temperatures, and radiation. Left unaddressed, corrosion can lead to catastrophic failures, resulting in economic and environmental liabilities. In nuclear applications, where metals and alloys, such as steel and zirconium, are extensively em- ployed inside and outside of the nuclear reactor, corrosion accelerated by high temperatures, neu- tron radiation, and corrosive atmospheres, corrosion becomes even more concerning. The objec- tives of this research are to study and develop surface modification techniques to protect zirconium cladding by the incorporation of a specific barrier coating, and to understand the issues related to the compatibility of the coatings examined in this work. The final goal of this study is to recommend a coating and process that can be scaled-up for the consideration of manufacturing and economic limits. This dissertation study builds on previous accident tolerant fuel cladding research, but is unique in that advanced corrosion methods are tested and considerations for implementation by industry are practiced and discussed. This work will introduce unique studies involving the materials and methods for accident tolerant fuel cladding research by developing, demonstrating, and consid- ering materials and processes for modifying the surface of zircaloy fuel cladding. This innova- tive research suggests that improvements in the technique to modify the surface of zirconium fuel cladding are likely. Three elements selected for the investigation of their compatibility on zircaloy fuel cladding are aluminum, silicon, and chromium. These materials are also currently being investigated at other labs as alternate alloys and coatings for accident tolerant fuel cladding. This dissertation also investigates the compatibility of these three elements as surface modifiers, by comparing their mi- crostructural and mechanical properties. To test their application for use in corrosive atmospheres, the corrosion behaviors are also compared in steam, water, and boric-acid environments. Various methods of surface modification were attempted in this investigation, including dip coating, diffu- sion bonding, casting, sputtering, and evaporation. The benefits and drawbacks of each method are discussed with respect to manufacturing and economic limits. Characterization techniques utilized in this work include optical microscopy, scanning electron microscopy, energy-dispersive spec- troscopy, X-ray diffraction, nanoindentation, adhesion testing, and atomic force microscopy. The composition, microstructure, hardness, modulus, and coating adhesion were studied to provide en- compassing properties to determine suitable comparisons and to choose an ideal method to scale to industrial applications. The experiments, results, and detailed discussions are presented in the following chapters of this dissertation research.

Thesis: S.B., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2018 / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 48-53). / Proton therapy has yet to implement an in-vivo, real-time, fault-tolerant integral dosimeter. Proposed in this thesis is a conceptual dosimeter to meet such requirements, relying on the radiation-stimulated production of F-centers in alkali halide salts. F-centers are optically active vacancies in the cation-anion lattice filled with a lone electron. These vacancies cause dimming bands in broad-band illumination of the crystal, and the vacancies increase in number in a proportional fashion to the dose received. The experiment proposed here will serve both to measure the dimming quality of various alkali halide salts as well as their decay rate in the dark at room temperature. Once performed, this experiment will demonstrate the feasibility of correlating dose to a real-time color measurement of an implanted alkali halide crystal in a patient undergoing proton radiotherapy. Thus far no such experiments have been performed, however the experimental assembly outlined herein is nearly fully constructed and nearly ready for experimentation upon time of completing this thesis. / by Daniel Schumaker. / S.B. / S.B. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering