No description available.

Salmonella Typhimurium continues to be a leading cause of human gastroenteritis worldwide. This organism is a facultative intracellular pathogen, meaning that it is able grow and reproduce within the host cell it inhabits. S. Typhimurium has the ability to invade and replicate within human intestinal epithelial cells, which in turn causes induced cell death or apoptosis. The human intestinal epithelial cells, HCT-8, were challenged with live, heat inactivated, and electron beam inactivated S. Typhimurium for various time points. Infected cell monolayers were collected for RNA extractions, and Real-time PCR was performed on the samples to analyze differential gene expression. Genes of the host cell that were expected to be differentially expressed were shortlisted and Real-Time PCR analysis was performed. Internalized Salmonella within the host cell was unable to be successfully visualized using fluorescent light microscopy. However, differential gene expression for a common transcriptional regulator and inflammatory chemokine were observed to be expressed significantly higher in response to e-beam inactivated Salmonella infection. Genes coding for extracellular and intracellular pattern-recognition receptors of the host cells were shown to be up-regulated in response to e-beam inactivated Salmonella infection at 4 and 24 hours, but were not statistically significant. Additional studies must be conducted to definitively confirm e-beam irradiated Salmonella has the ability to invade human host cells.

No description available.

When a fire reaches the point of flashover the hot gases inside the burning room ignite resulting in furnace-like conditions. Thereafter, the building frame experiences temperatures sufficient to compromise its structural integrity. Physical and mathematical models help to predict when this will happen. This thesis looks at both the thermal and structural aspects of modelling a frame exposed to a post-flashover fire. The temperatures in the frame are calculated by solving a 2D heat conduction equation over the cross-section of each beam. The solution procedure uses the finite element method with automatic mesh generation/adaption based on the Delaunay triangulation process and the recovered heat flux. With the Euler-Bernoulli assumption that the cross-section of a beam remains plane and perpendicular to the neutral line and that strains are small, an error estimator, based on the work of Bank and Weiser [9], has been derived for finite element solutions to small-deformation, thermoelastic and thermoplastic frame problems. The estimator has been shown to be consistent for all finite element solutions and asymptotically exact when the solution involves appropriate higher degree polynomials. The asymptotic exactness is shown to be closely related to superconvergence properties of the approximate solution in these cases. Specifically, with coupled bending and compression, it is necessary to use quadratic approximations, instead of linear, for the compression and twisting terms to get a global O(h2) rate of convergence in the energy norm, some superconvergence properties and asymptotic exactness with the error estimator.

No description available.

No description available.

No description available.

Using electron beam evaporation for the production of polycrystalline silicon (pc-Si) thin-film solar cells is an attractive alternative to PECVD deposition. Due to its faster deposition rate, using evaporation technology could significantly reduce module production costs. Other advantages are lower running costs, and the fact that no toxic gases are involved. However, currently no on-shelf equipment is available, and research in this field often relies on in-house designed systems. These can have various problems with reliability, deposition uniformity, and due to their custom design require frequent maintenance. In this work, a newly purchased electron beam evaporation system was upgraded and redesigned to be capable of depositing amorphous Si diodes for the fabrication of pc-Si thin-film solar cells. The main goal of the upgrade was to provide a safe and reliable tool which allows for the deposition of high purity semiconductor material. Reliable and safe operation was accomplished by designing the entire electrical supply circuit and incorporating various safety interlocks. Source cross-contamination issues were addressed by installing a specially designed shroud (source housing). To provide uniform substrate temperatures up to 600??C, a heater was specially designed, fabricated, installed and tested. Accurate design of all mechanical system components was realised by using 3D product design software (ProEngineer). The new evaporator was commissioned, which included testing and calibration of all the system components required for depositing on substrate sizes of up to 10x10cm2. Over this area a Si film thickness uniformity of +/-2%, performed with a maximum deposition rate of 7nm/s was achieved. Initial experiments using solid phase crystallisation and rapid thermal annealing revealed a sheet resistance uniformity of +/-4% for the Phosphorus and +/-7% for the Boron dopant effusion cell. Experimentation via Raman spectrometry and X-ray diffraction has revealed good crystalline properties, of the crystallised Si films, which is comparable to those of existing evaporation systems. Although the system was upgraded to achieve deposition pressures below 3x10-7 mbar, experiments have shown that this quality of vacuum may not be necessary for the fabrication of low impurity films. The system is now ready for further research in the field of thin-film photovoltaics, and the first functioning devices have been fabricated.

Thesis (Ph. D.)--Oregon Graduate Center, 1988.

Thesis(M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.