Two outbreaks of salmonellosis were linked to the consumption of raw California almonds in 2001 and 2004. Current federal regulations mandate that all almonds grown in California are to be treated with a process that results in a 4-log reduction of Salmonella. Since four out of the five approved technologies to pasteurize almonds rely on the application of heat to control Salmonella, the evaluation of alternative technologies against heat resistant Salmonella Senftenberg was imminent. In this study, almonds that were inoculated with S. Enteritidis PT 30 and S. Senftenberg, were treated with electron beam irradiation (e-beam), blanching and oil roasting. The thermal death time (D-value) for S. Enteritidis PT 30 when treated with e-beam was 0.90 kGy, 15 s when subjected to blanching at 88 degrees C, and 13 s when treated with oil at 127 degrees C. Irradiation and thermal resistance of S. Senftenberg was not significantly different (P > 0.05) from S. Enteritidis PT 30. The commercial application of e-beam as a pathogen intervention was assessed through Monte Carlo simulations (MCS) and experimental measurements. The sensory characteristics of almonds commercially treated by e-beam, blanching and roasting were assessed by a consumer panel. Irradiated and blanched almonds did not differ in consumer overall like (P > 0.05). Bitterness and rancidity attributes of irradiated almonds were between a "dislike slightly" and "dislike moderately", whereas blanched and roasted almonds were between "neither like nor dislike" and "like slightly". Almonds commercially irradiated, blanched and roasted were subjected to an accelerated shelf-life test (ASLT) evaluating percentage free fatty acids, peroxide value, and 2-thiobarbituric acid reactive substances (TBARs). No clear differences between treatments were observed at any given point in time in any of the chemical tests. A gas chromatography-mass-spectrometry-olfactometry (MDGC-MS-O) technology was used to compare full aroma and flavor profiles from raw and e-beam irradiated almonds. Differences in the aroma/odor profile and the taste analysis revealed that the difference between raw and irradiated almonds is extremely subtle. In conclusion, e-beam may be a feasible technology to control Salmonella in almonds if used at low doses, as a part of a series of interventions.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 169-172). Also available via the Internet.

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Thesis --(MSc. (Medical Physics)), 2009. / Introduction The primary role of breast cancer treatment with radiation is to deliver a sufficient radiation dose to the cancer cells without unduly causing biological damage to the healthy tissues. For over 50 years, electron beam therapy has been an important modality for providing an accurate dose of radiation to superficial cancers and disease and for limiting the dose to underlying normal tissues and structures in particular to boost the dose to the tumour bed and surgical scars after mastectomy. The Monte Carlo code MCNP5 was used to determine the effect of silicone gel breast prosthesis on the electron beam dose distribution. Materials and Method Percentage depth dose curves (PDD) for 6, 9, 12, and 15 MeV electron energies along the electron central axis depth dose distributions in a water phantom and with silicone prosthesis immersed in a water phantom were simulated using MCNP5. In order to establish the accuracy of the MCNP5 code, the depth dose curves obtained using MCNP5 were compared against the measured depth dose curves obtained from the Varian 2100C linear accelerator. The simulated depth dose curves with silicone prosthesis immersed in water were compared to the measured depth dose curves with the vi silicone prosthesis in water. The dose at the interface of the prosthesis with water was measured using thermoluminiscent dosimeters. Results The simulated and measured depth dose curve and the investigated dosimetric parameters are within 2%. Simulations in the presence of silicone showed a decrease in dose as the at the interface as the beam passes from the prosthesis to water for most energies however, for 15 MeV beam there is an increase in dose at the interface between the prosthesis and water and this was verified by physical measurements. Conclusion There were good correlations between the measured and MCNP simulated depth dose curve. Differences were in order of 2%. Small deviations occurred due to the fact that the simulations assumed a monoenergetic beam that exits the accelerator head, while in the measured results the beam exiting from the accelerator head includes scatted radiation from the collimators and the applicator. The presence of the prosthesis does not perturb the electron beam central axis depth dose curve however, the 15 MeV beam enhanced the dose in front of the interface between the prosthesis and water. Despite the limitations mentioned above MCNP5 results agree reasonably with the measured results. Hence, MCNP5 can be very useful in simulating electron percentage depth dose data.

The effect of electron beam irradiation upon microbiological quality and safety of fresh-cut tomatoes was studied. Preliminary studies were conducted to ensure reliability of the rifampicin-resistant strain versus the parent strain of Salmonella serovar Montevideo for use in this study. Growth curve, heat tolerance and lactic acid resistance studies were performed, all of which showed no differences in behavior between the organisms. Fresh tomatoes were obtained from a local supplier and then cut into cubes with stem scars being separated. Both cubes and stem scars were inoculated with a rifampicin- resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups and treated by electron beam irradiation at 0.0 kGy (control), 0.7 kGy or 0.95 kGy. The effect of electron beam irradiation was determined for Salmonella, yeast, mold, and lactic acid bacteria (LAB) populations as well as pH on tomato cubes and stem scars over a 15-day storage period at 4??C. Results indicated that while irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the microbial populations between treatments of 0.7 kGy or 0.95 kGy. Irradiation at either dose resulted in a significant reduction of Salmonella Montevideo when compared to the control, with an initial reduction of 1.8 and 2.2 log10 CFU/g on tomatoes for 0.7 kGy and 0.95 kGy, respectively. LAB, yeasts and molds were more resistant to the treatment than Salmonella. Populations present on stem scars and tomato cubes did experience some differences in log reductions, possibly due to the protective effect of the stem scar on microorganisms. However, no differences were detected between the two Salmonella serotypes in response to irradiation treatment. This study indicates that doses of irradiation greater than 1 kGy should be used in fresh-cut tomatoes to eliminate significant populations of pathogens, as well as to ensure the microbial quality of the product. Additional studies also need to be conducted to examine the effects of higher irradiation doses on the sensory qualities of fresh-cut tomatoes.

The relation between the electrical property and the material microstructure of InSb grown on Si utilizing electron beam evaporation technology has been investigated. The improvement of the InSb electrical property with controlling annealing environment after post annealing is demonstrated. The crystal structure of InSb thin films were characterized with X-ray diffraction (XRD) and the surface morphology was examined by scanning electron microscope (SEM). The composition of InSb films was analyzed by electron probe microscope analysis (EPMA) and the mobility of InSb films were measured by Hall measurement. Finally, the grain size and texture of InSb films microstructure were studied by transmission electron microscope (TEM). The films were grown with different In/Sb flux ratio by controlling electron energy during electron evaporation. The results show that the poly-InSb films were formed due to large lattice difference between Si and InSb . The InSb films which had higher In concentration behave higher mobility. The highest mobility of the as-grown film is around 12000(cm2/Vs). The mobility of InSb can be improved to 26000 (cm2/Vs) by added extra Sb source annealed at 500¢J for 5 hours in an sealed ampoule. The extra Sb which dissolved with the existed In droplet in the film and adjust the composition ratio of In/Sb closing to 1:1. Besides, the post-annealing process provides the InSb film to gain much better texture. Both these two factors contribute to improve the electrical property of InSb films.

The effect of electron beam irradiation upon microbiological quality and safety of fresh-cut tomatoes was studied. Preliminary studies were conducted to ensure reliability of the rifampicin-resistant strain versus the parent strain of Salmonella serovar Montevideo for use in this study. Growth curve, heat tolerance and lactic acid resistance studies were performed, all of which showed no differences in behavior between the organisms. Fresh tomatoes were obtained from a local supplier and then cut into cubes with stem scars being separated. Both cubes and stem scars were inoculated with a rifampicin- resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups and treated by electron beam irradiation at 0.0 kGy (control), 0.7 kGy or 0.95 kGy. The effect of electron beam irradiation was determined for Salmonella, yeast, mold, and lactic acid bacteria (LAB) populations as well as pH on tomato cubes and stem scars over a 15-day storage period at 4??C. Results indicated that while irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the microbial populations between treatments of 0.7 kGy or 0.95 kGy. Irradiation at either dose resulted in a significant reduction of Salmonella Montevideo when compared to the control, with an initial reduction of 1.8 and 2.2 log10 CFU/g on tomatoes for 0.7 kGy and 0.95 kGy, respectively. LAB, yeasts and molds were more resistant to the treatment than Salmonella. Populations present on stem scars and tomato cubes did experience some differences in log reductions, possibly due to the protective effect of the stem scar on microorganisms. However, no differences were detected between the two Salmonella serotypes in response to irradiation treatment. This study indicates that doses of irradiation greater than 1 kGy should be used in fresh-cut tomatoes to eliminate significant populations of pathogens, as well as to ensure the microbial quality of the product. Additional studies also need to be conducted to examine the effects of higher irradiation doses on the sensory qualities of fresh-cut tomatoes.

In this study, the AZO thin films were deposited with various manufacturing conditions, such as working pressure of oxygen and substrate temperature, by e-beam evaporation. The microstructure of the AZO film was observed by SEM and AFM. Sheet resistance was measured using four-point probe method. Optical transmittance was measured in the visible range by UV spectrophotometer. Finally, AZO transparent film was used as a substitute for ITO to fabricate the radiation-resistant glasses. The optimum parameters for depositing AZO films are glass substrates of 80¢J and working pressure of 1¡Ñ10-4 Torr. The film resistance is 9.2¡Ñ10-4 £[-cm with a film thickness of 60 nm. The refractive index was measured to be 2.05 at a wavelength of 510 nm. The optical transmittance of the prepared films was above 83 % in the visible range. The manufacturing conditions for depositing AZO multilayer coatings are working pressure of 5.0¡Ñ10-5 Torr, ion gun working pressure of 6.0¡Ñ10-5 Torr, voltage of 6.2 V, oxygen gas flow rate of 36 sccm and glass substrates of 80¢J. The optical transmittance of the glass was above 94 % in the visible range.