Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Uranium has been mined for many years and used for fuel for nuclear reactors and materials for atomic weapons, ammunition, and armor. While the radioactivity associated with uranium mining has been linked to the development of lung and kidney cancers, and leukemia, little is known about the direct chemical genotoxicity of uranium. The overall hypothesis of the current research is that uranium can produce DNA damage by chemical genotoxicity mechanisms. Three specific aims were tested. In Aim 1, specific DNA lesions caused by direct interaction of uranium and DNA were investigated. Chinese Hamster Ovary cells (CHO) with mutations in various DNA repair pathways were exposed to 0 – 300 μM of soluble depleted uranium (DU) as uranyl acetate (UA) for 0 – 48 hr. Results indicate that UA readily enters CHO cells, with the highest concentration localizing in the nucleus. Clonogenics assay shows that UA is cytotoxic in each cell line with the greatest cytotoxicity in the base excision repair deficient EM9 cells and the nuclear excision repair deficient UV5 cells compared to the non-homologous end joining deficient V3.3 cells and the parental AA8 cells after 48 hr. This indicates that UA is forming DNA adducts that may be producing single strand breaks through hydrolysis rather than double strand breaks in CHO cells. Fast Micromethod® results indicate an increased amount of single strand breaks in the EM9 cells after 48 hr UA exposure compared to the V3.3 and AA8 cells. In Aim 2, the role of oxidative stress in producing DNA lesions was determined. Cellular oxidative stress has been implicated in the genotoxicity of many heavy metals as a mechanism of induced DNA damage. To investigate this possible mechanism, human bronchial epithelial cells (16HBE14o⁻) were exposed to 30 ppb (0.13 μM U) UA for 2 – 24 hr. UA did not significantly induce oxidative stress compared to untreated cells at 3 – 4 hr time points. These results suggest that cellular oxidative stress is not a major pathway of DU genotoxicity at low concentrations. In Aim 3, DNA damage response to uranium-induced DNA damage was investigated. It has been widely reported that metals can be genotoxic by inhibiting DNA repair. Cultured cells were co-exposed to 0.13 μM UA in the presence of 0 – 25 μM of etoposide for 0 – 48 hr. Results indicate that UA inhibited double strand break repair. Coexposures of etoposide and UA synergistically induced cytotoxicity compared to individual treatments and untreated cells. Co-exposed UA and etoposide treated 16HBE14o⁻ cells exhibited a decrease in phosphorylation of DNA repair proteins compared to etoposide treatments. Untreated and UA-treated 16HBE14o⁻ cells did not induce phosphorylation of DNA repair proteins. These results suggest that DU inhibits double strand break DNA repair at low concentrations in the presence of a known DNA double-strand damaging agent, etoposide. The inhibition of DNA repair by DU at environmentally relevant concentrations suggests a novel means by which uranium may exert its genotoxic effects. Results found at low dose exposures are not consistent with alterations seen with radioactivity, suggesting that the effects of uranium at low doses are due to its chemical genotoxic effects. Understanding how uranium reacts with DNA is important to better understand how this suspected carcinogen induces cancer and to help to elucidate mechanisms that produce cancers in people exposed to uranium.

Jumonji C (JmjC) domain containing proteins comprise a large family of enzymes that catalyse oxidative reactions. The jumonji domain containing protein 6 (JMJD6) has pleiotropic functions as a lysyl hydroxylase and arginyl demethylase. Previous studies have shown that Jmjd6 is involved in histone modification, mRNA splicing and regulation of polymerase II pause release. A constitutive knockout of Jmjd6 in mice is neonatal lethal and shows defects in macrophage host responses. Recently, JMJD6 was shown to support Foot-and-mouth disease virus replication through interactions with the dead-box RNA helicase Dhx9. This PhD thesis aims to further explore functions of Jmjd6 in macrophages and its roles during viral infections. The hypothesis is that through interactions with RNA helicases, Jmjd6 regulates host responses to foreign nucleic acids and/or has functions as a host factor for replication of DNA and/or RNA viruses. Testing of this hypothesis required the generation of Jmjd6-deficient cell recourses. A new conditional Jmjd6 mouse allele was characterised and a method optimised to knockout the gene in bone marrow-derived macrophages (BMDM) using TAT-Cre recombinase. To study vaccinia (VACV) and influenza A virus (IAV) infections in human cell lines, JMJD6 was depleted using RNA interference or CRISPR-Cas9 gene editing. In BMDM, JMJD6 expression was up-regulated in the late phase of lipopolysaccharide stimulation. The nuclear expression pattern of Jmjd6 in BMDM overlapped with that of DDX41 but not with DHX9, two RNA helicases that have been implicated in sensing of viral DNA and RNA, respectively. Deletion of Jmjd6 in BMDM reduced induction of type I interferon response genes after stimulation with synthetic analogs of viral RNA. To characterise the role of JMJD6 during infection with a DNA virus, Jmjd6-deficient cells were infected with VACV. Knockout of Jmjd6 reduced VACV growth in macrophages but not in HeLa cells. In contrast to HeLa cells, Jmjd6-deficient macrophages displayed abnormal localisations of viral factories and increased cell death, showing that Jmjd6 is specifically required for productive VACV infection in macrophages. To further analyse whether Jmjd6 has pro- or anti-viral functions during RNA virus infection, JMJD6 depleted A549 cells were infected with IAV. JMJD6 depletion in A549 drastically reduced IAV growth from an early stage of infection. Preliminary data indicate that this phenotype is related to a defect in nuclear import of IAV ribonucleoprotein complexes. In summary, this work has identified JMJD6 as a novel pro-viral host factor for VACV and IAV infection and has underpinned its importance for macrophage functions.

he feasibility of sequestering supercritical CO2 in depleted gas reservoirs. The experimental runs involved the following steps. First, the 1 ft long by 1 in. diameter carbonate core is inserted into a viton Hassler sleeve and placed inside an aluminum coreholder that is then evacuated. Second, with or without connate water, the carbonate core is saturated with methane. Third, supercritical CO2 is injected into the core with 300 psi overburden pressure. From the volume and composition of the produced gas measured by a wet test meter and a gas chromatograph, the recovery of methane at CO2 breakthrough is determined. The core is scanned three times during an experimental run to determine core porosity and fluid saturation profile: at start of the run, at CO2 breakthrough, and at the end of the run. Runs were made with various temperatures, 20°C (68°F) to 80°C (176°F), while the cell pressure is varied, from 500 psig (3.55 MPa) to 3000 psig (20.79 MPa) for each temperature. An analytical study of the experimental results has been also conducted to determine the dispersion coefficient of CO2 using the convection-dispersion equation. The dispersion coefficient of CO2 in methane is found to be relatively low, 0.01-0.3 cm2/min.. Based on experimental and analytical results, a 3D simulation model of one eighth of a 5-spot pattern was constructed to evaluate injection of supercritical CO2 under typical field conditions. The depleted gas reservoir is repressurized by CO2 injection from 500 psi to its initial pressure 3,045 psi. Simulation results for 400 bbl/d CO2 injection may be summarized as follows. First, a large amount of CO2 is sequestered: (i) about 1.2 million tons in 29 years (0 % initial water saturation) to 0.78 million tons in 19 years (35 % initial water saturation) for 40-acre pattern, (ii) about 4.8 million tons in 112 years (0 % initial water saturation) to 3.1 million tons in 73 years (35 % initial water saturation) for 80-acre pattern. Second, a significant amount of natural gas is also produced: (i) about 1.2 BSCF or 74 % remaining GIP (0 % initial water saturation) to 0.78 BSCF or 66 % remaining GIP (35 % initial water saturation) for 40-acre pattern, (ii) about 4.5 BSCF or 64 % remaining GIP (0 % initial water saturation) to 2.97 BSCF or 62 % remaining GIP (35 % initial water saturation) for 80-acre pattern. This produced gas revenue could help defray the cost of CO2 sequestration. In short, CO2 sequestration in depleted gas reservoirs appears to be a win-win technology.

he feasibility of sequestering supercritical CO2 in depleted gas reservoirs. The experimental runs involved the following steps. First, the 1 ft long by 1 in. diameter carbonate core is inserted into a viton Hassler sleeve and placed inside an aluminum coreholder that is then evacuated. Second, with or without connate water, the carbonate core is saturated with methane. Third, supercritical CO2 is injected into the core with 300 psi overburden pressure. From the volume and composition of the produced gas measured by a wet test meter and a gas chromatograph, the recovery of methane at CO2 breakthrough is determined. The core is scanned three times during an experimental run to determine core porosity and fluid saturation profile: at start of the run, at CO2 breakthrough, and at the end of the run. Runs were made with various temperatures, 20°C (68°F) to 80°C (176°F), while the cell pressure is varied, from 500 psig (3.55 MPa) to 3000 psig (20.79 MPa) for each temperature. An analytical study of the experimental results has been also conducted to determine the dispersion coefficient of CO2 using the convection-dispersion equation. The dispersion coefficient of CO2 in methane is found to be relatively low, 0.01-0.3 cm2/min.. Based on experimental and analytical results, a 3D simulation model of one eighth of a 5-spot pattern was constructed to evaluate injection of supercritical CO2 under typical field conditions. The depleted gas reservoir is repressurized by CO2 injection from 500 psi to its initial pressure 3,045 psi. Simulation results for 400 bbl/d CO2 injection may be summarized as follows. First, a large amount of CO2 is sequestered: (i) about 1.2 million tons in 29 years (0 % initial water saturation) to 0.78 million tons in 19 years (35 % initial water saturation) for 40-acre pattern, (ii) about 4.8 million tons in 112 years (0 % initial water saturation) to 3.1 million tons in 73 years (35 % initial water saturation) for 80-acre pattern. Second, a significant amount of natural gas is also produced: (i) about 1.2 BSCF or 74 % remaining GIP (0 % initial water saturation) to 0.78 BSCF or 66 % remaining GIP (35 % initial water saturation) for 40-acre pattern, (ii) about 4.5 BSCF or 64 % remaining GIP (0 % initial water saturation) to 2.97 BSCF or 62 % remaining GIP (35 % initial water saturation) for 80-acre pattern. This produced gas revenue could help defray the cost of CO2 sequestration. In short, CO2 sequestration in depleted gas reservoirs appears to be a win-win technology.

The quality of the spectral data collected by radiological survey systems depends on many factors including the survey environment, configuration of the system and its detectors, and the radionuclides in question. Algorithms in the field of machine learning have the potential to classify data that would be difficult and time-intensive for a human to analyze. Depleted and natural uranium spectra are of particular interest due to known contamination at domestic sites and world-wide. Several machine learning classifiers were developed with data collected from laboratory experiments. This thesis demonstrates the potential of machine learning algorithms to discriminate gamma-ray emitting sources using sparse, or low-count statistic, data. Effectiveness has been demonstrated for discriminating chemical forms of uranium, mixtures with differing uranium isotope distributions, and predicting source masses given certain detector geometries and a known target distribution. All activity has been supported by the U.S. Army Engineering Research and Development Center (ERDC).

No description available.

Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / A technique for measuring and characterizing transistor noise is presented. The primary goal of the measurements is to locate the 1/f noise corner for select transistors in Silicon-on-Sapphire processes. Additionally, the magnitude of the background channel noise of each transistor is measured. With this data, integrated circuit (IC) engineers will have a qualitative and quantitative resource for selecting transistors in designs with low noise requirements. During tests, transistor noise behavioral change is investigated over varying channel lengths, device type (N-type and P-type), threshold voltage, and bias voltage levels. Noise improvements for increased channel lengths from minimal, 1.0μm, and 4.0μm are measured. Transistors with medium and high threshold voltages are tested for comparison of their noise performance. The bias voltages are chosen to represent typical design values used in practice, with approximately 400 mV overdrive and a drain-to-source voltage range of 0.5 to 3.0V. The transistors subjected to tests are custom designed in Peregrine’s 0.5μm (FC) and 0.25μm (GC) Silicon-on-Sapphire (SOS) processes. In order to allow channel current noise to dominate over other circuit noise, the transistors have extraordinarily large aspect ratios (~2500 - 5000). The transistor noise produced is amplified and measured over a frequency range of 1kHz - 100MHz. This range allows the measurement of each device’s low and high frequency noise spectrum and resulting noise corner.

Texture evolution of depleted uranium is investigated using a viscoplastic self-consistent model. Depleted uranium, which has the same structure as alpha-uranium, is difficult to model as it has an orthorhombic symmetry structure, as well as many twin systems which must be addressed in order to properly simulate the textural evolution. The VPSC method allowed for a flexible model which could not only encompass the low symmetry component but also the twinning components of depleted uranium. The model focuses on the viscoplastic regime only, neglecting the elastic regime of deformation, and uses a self-consistent method to solve the model. Different deformation processes, such as torsion, rolling, and swaging, are simulated and the theoretical textures, plotted as pole figures or inverse pole figures, are compared with previous experimental textures found for alpha uranium from previous experimental sources. A specific twin system, the (176)[512] system, is also given special consideration. This twin system is a dominant deformation mode for alpha uranium at high strain rates, but is quite elusive in general. Different deformation processes are compared where this twin system is active and not active. This allows comparison on the effect of this twin on the overall texture of depleted uranium. In addition, a sample of depleted uranium from Y12 which was analyzed for (176)[512] twins is compared to theoretical results from a VPSC simulation where the (176)[512] twin is active.

Abstract In this thesis, a Multi-gate PD SOI Device is realized. The inverse narrow channel effect of the device is also studied. In the Multi-gate PD SOI structure, it has three-surface gate on the silicon MESA Island, which can promote the device performance. However, for eliminating the abnormal corner leakage current in the MESA Island, the process of rounded corner is used. In order to overcome the floating body effect, we use the Schottky body contact. According to the 3-D DAVINCI device simulation and the measurement results, the Multi-gate PD SOI device presents the excellent characteristics: low threshold voltage, low subthreshold factor and high breakdown voltage. In addition, comparing the Multi-gate device with that of the conventional one, the excess drain current gain is observed. In order to understand the behavior of INCE in Multi-gate PD SOI Device in depth, we use the concept of overlap depletion region to derive the expressions of threshold voltage shift. Owing to the device has rounded corner, we also study the rounded corner effect in the model formulation. Comparing calculation with that of the experiment one, the calculation shows agreement with the experiments.