Nanofibres are useful in a broad range of applications in areas such as medical science, food science, materials engineering, environmental engineering, and energy and electronics due to their outstanding characteristics: their small size, high surface-to-volume ratio, high porosity, and superior mechanical performance. Recently, controlled drug delivery systems have gained significant attention, especially with respect to the use of polymer nanofibres. For these systems, the ability to control of the length of the polymer nanofibre is important because the amount of drug released depends on the length of the fibre. Electrospinning is the simplest and most cost-effective method of fabricating polymer nanofibres. In the process, a high voltage is used to create an electrified jet which will eventually become a nanofibre. The electrified jet ejects when a high voltage is applied to the electrospinning setup. On the other hand, the jet does not eject when the applied voltage is below the threshold voltage. It is therefore possible to fabricate and chop nanofibres by controlling the values of the voltages applied and a special high-voltage pulsed power supply has been developed for this purpose. In this research, an IGBT-based pulsed power supply has been designed and built to be used for non-continuous-mode electrospinning. The IGBTs are connected in series to deliver high voltage pulse voltages to an electrospinning setup. The IGBT-based pulsed power supply is capable of producing controllable square pulses with a width of a few hundred microseconds to DC and amplitudes up to 10 kV. The technique of non-continuous-mode electrospinning was tested using the pulsed power supply designed in this work. The new system was able to fabricate and chop nanofibres with PEO and alginate/PEO solutions. It was concluded that the minimum pulse width that can initiate an electrified jet is approximately 80 ms for the parameters used in this study. A longer period produces a more constant jet during the pulse-on voltage when the duty ratio is the same value. It is also highly likely that a jet is always ejected during the pulse-on voltage when the duty ratio is more than 40 %.

Air sparging is a technique used to remediate gasoline contamination. In sparging, air is injected below the target zone and removes contamination via two separate mechanisms; volatilization and biodegradation. In volatilization, the air contacts the contamination as it moves upward. The contaminant will partition to the vapor phase based on its volatility and will be removed as the air reaches the atmosphere. For biodegradation, the oxygen in the airstream is used for microbial activity. Pulsed air sparging, otherwise known as pulsed biosparging, has been found to be more effective than continuous air sparging. Pulsed biosparging enhances treatment because it induces groundwater movement and mixing. The general mechanisms for treatment of gasoline sources using air sparging are relatively well characterized. However, air flow through the subsurface and the total hydrocarbon mass lost are difficult to predict and quantify. This project was intended to quantify the mass lost through volatilization and through biodegradation at the E10 gasoline source using pulsed biosparging, and to determine the effect of the source zone removal on downgradient dissolved BTEX concentrations. The remedial system consisted of two major components: the air sparging system, with three injection points; and a soil gas collection system. The soil gas collection system was comprised of an airtight box that covered the source area and the monitoring wells upgradient and downgradient of the source. Off-gas from the soil gas collection system was monitored continuously using a PID. The off-gas was also sampled frequently for BTEX, pentane, and hexane to determine the hydrocarbon mass removed; and for O2 and CO2 to determine biodegradation rates. The remedial system ran for approximately 280 hours over 33 days. Of the estimated 22.3 kg of gasoline residual in the source zone, 4.6 kg or 21% of the residual was removed via volatilization and 4.9 kg or 22% of the residual was removed via biodegradation. Leakage outside the system was estimated at less than 0.1% of the total mass. Groundwater samples were collected when the last sparged air was calculated to arrive at the row 2 downgradient fence. The average BTEX groundwater concentration after sparging was 40% of the pre-sparging concentration. The benzene mass discharge decreased 27%, the ethylbenzene mass discharge decreased 65%, the p/m-xylene mass discharge decreased 6%, and the o-xylene mass discharge decreased 5%. The mass discharge for naphthalene and TMB isomers increased 19%. However, these values fit in with long-term groundwater concentration trends. Additional sampling is recommended to determine if the sparging made a significant impact on mass discharge leaving the source.

Nanofibres are useful in a broad range of applications in areas such as medical science, food science, materials engineering, environmental engineering, and energy and electronics due to their outstanding characteristics: their small size, high surface-to-volume ratio, high porosity, and superior mechanical performance. Recently, controlled drug delivery systems have gained significant attention, especially with respect to the use of polymer nanofibres. For these systems, the ability to control of the length of the polymer nanofibre is important because the amount of drug released depends on the length of the fibre. Electrospinning is the simplest and most cost-effective method of fabricating polymer nanofibres. In the process, a high voltage is used to create an electrified jet which will eventually become a nanofibre. The electrified jet ejects when a high voltage is applied to the electrospinning setup. On the other hand, the jet does not eject when the applied voltage is below the threshold voltage. It is therefore possible to fabricate and chop nanofibres by controlling the values of the voltages applied and a special high-voltage pulsed power supply has been developed for this purpose. In this research, an IGBT-based pulsed power supply has been designed and built to be used for non-continuous-mode electrospinning. The IGBTs are connected in series to deliver high voltage pulse voltages to an electrospinning setup. The IGBT-based pulsed power supply is capable of producing controllable square pulses with a width of a few hundred microseconds to DC and amplitudes up to 10 kV. The technique of non-continuous-mode electrospinning was tested using the pulsed power supply designed in this work. The new system was able to fabricate and chop nanofibres with PEO and alginate/PEO solutions. It was concluded that the minimum pulse width that can initiate an electrified jet is approximately 80 ms for the parameters used in this study. A longer period produces a more constant jet during the pulse-on voltage when the duty ratio is the same value. It is also highly likely that a jet is always ejected during the pulse-on voltage when the duty ratio is more than 40 %.

A volumetric heat source finite element model is proposed to simulate the key hole effect during the Nd:YAG pulse laser welding. The measured data has been used to correlate the volumetric model parameters and the laser parameters. The laser power distributed in the beam cross area is in a Gaussian type. Two heat transfer models are employed in the fusion area, i.e the surface absorption heat transfer model in the low power intensity region and the keyhole heat transfer model in the high power intensity region. An experimentally measured critical power intensity is introduced to identify the occurrence of keyhole effect. The value of critical power intensity is dependent on the welding material. A series of MARC finite element simulations based on the proposed single pulse model are performed to investigate the feasibility and accuracy of this proposed pulse laser welding model. Different power and welding duration pulse laser have used to weld the S304L specimens. The results indicate a good agreement between the simulated and measured shape and size of the weld pool with different laser energy intensities. The validity of the proposed model is confirmed for the S304L steel. The temperature and residual stress distributions around the welding pool in a continuous pulse welding and two sheet overlap welding have also been studied by using the proposal model. The numerical results indicate that the pulse energy, duration and dwell period may affect the residual stress distribution and post-weld deformation significantly. All these results reveal that the proposed volumetric heat source finite element model is a feasible model to analyze the welding phenomena during the pulse laser welding. The results indicate that the pulse dwell period increase in dual pulse laser welding the residual stress decrease on the top of the weld spot surface. The results also show the lower residual stress in multi spots pulse laser welding with smaller weld spots center pitch and weld spot dwell period.

Invented in the 1950s, gel electrophoresis has now become a routine analytical method to verify the size of nucleic acids and proteins in molecular biology labs. Conventional gel electrophoresis can successfully separate DNA fragments from several base pairs to a few tens of kilo base pairs, beyond which a point is reached that DNA molecules cannot be resolved due to the size independent mobility. In this case, pulsed field gel electrophoresis (PFGE) was introduced to extend the range of DNA fragment sizes that can be effectively separated. But despite the incredible success of PFGE techniques, some important drawbacks remain. First, separation time is extremely long, ranging from several hours to a few days. Second, detection methods still rely on staining the gel after the run. Real time observation and study of band migration behavior is impossible due to the large size of the PFGE device. Finally, many commercial PFGE instruments are relatively expensive, a factor that can limit their accessibility both for routine analytical and preparative use as well as for performing fundamental studies. In this research, a miniaturized PFGE device was constructed with dimension 2cm x 2.6cm, capable of separating DNA fragments ranging from 2.5kb to 32kb within three hours using low voltage. The separation process can be observed in real time under a fluorescence microscope mounted with a cooled CCD camera. Resolution and mobility of the sample were measured to test the efficiency of the device. We also explored manipulating DNA fragments by end labeling DNA molecules with quantum dot nanocrystals. The quantum dot-DNA conjugates can be further modified through binding interactions with biotinylated single-stranded DNA primers. Single molecule visualization was performed during gel electrophoresis and the extension length, entanglement probability and reorientation time of different conjugates were measured to study their effect on DNA migration through the gel. Finally, electrophoresis of DNA conjugates was performed in the miniaturized PFGE device, and shaper bands were observed compared with the non end-labeled sample. Furthermore, by end-labeling DNA with quantum dots, the migration distance of shorter fragments is reduced, providing the possibility of separating a wider range of DNA fragment sizes on the same gel to achieve further device miniaturization.

Poultry slaughtering encompasses a series of processing steps with the objective of harvesting the consumable meat. The scalding process consists of the submersion of carcasses in hot water tanks to facilitate the removal of feathers during slaughter. However, the use of a common scalding tank increases the likelihood of carcass cross contamination considering that dirt, fecal material and even digestive and intestinal contents carrying pathogens and other bacteria are widely spread during this operation. Similar cross contamination occurs in the process of chilling carcasses, which also requires submersion of broilers in communal tanks filled with ice and cold water. A plausible approach to reduce contamination in scalders or chillers is the use of Pulsed Electric Fields (PEF) to decontaminate scalder/ chiller water. PEF uses electricity to kill bacteria suspended in liquid media and could be utilized in poultry scalders and chillers to reduce bacterial contamination on carcasses and reduce the potential risk of pathogens reaching the final consumer. A pilot scale system was assembled by the use of a pulse electric field generator (Model SF-700, Simmons. Eng. Co., Dallas, GA) coupled with a commercial scalding tank (Dunkmaster®, Knase Company Inc, MI). C. coli and C. jejuni along with marker strains of Novobiocin and Nalidixic acid resistant S. typhimurium and S. enteritidis strains were used in challenge studies evaluating the effects of the PEF on carcasses, scalder and chiller water contamination. The system was evaluated with 0, 0.5, and 1% sodium chloride in the water with 40 volts of electric current and 0.54 of amperage. Samples were collected at 0, 40, 80, 160, 200 s of treatment with a 10 s on, 5 s off cyclical pulses. The use of PEF in regular scalder/chiller water showed little effect on Salmonella and Campylobacter reductions. However, with the addition of 0.5% NaCl caused a significant (P<0.5) log CFU/ml reduction of Salmonella and Campylobacter within the scalder/chiller water at 40, 80, and 160 seconds respectively.

名古屋大学博士学位論文 学位の種類 : 医学博士(論文) 学位授与年月日:平成4年7月20日 宮口和彦氏の博士論文として提出された

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<p>The thesis explores preparation and properties of bismuthiron garnet (BIG) films and the incorporation of BIG films intoone-dimensional magneto-optical photonic crystals (MOPCs).</p><p>Films were prepared by pulsed laser deposition. Weinvestigated or measured crystallinity, morphology,film-substrate interface, cracks, roughness, composition,magnetic coercivity, refractive index and extinctioncoefficient, and magneto-optical Faraday rotation (FR) andellipticity. The investigations were partly performed onselected samples, and partly on two series of films ondifferent substrates and of different thicknesses. BIG filmswere successfully tested for the application of magneto-opticalvisualization. The effect of annealing in oxygen atmosphere wasalso investigated - very careful annealing can increase FR byup to 20%. A smaller number of the above mentionedinvestigations were carried out on yttrium iron garnet (YIG)films as well.</p><p>Periodical BIG-YIG multilayers with up to 25 single layerswere designed and prepared with the purpose to enhance FR at aselected wavelength. A central BIG layer was introduced asdefect layer into the MOPC structure and generated resonancesin optical transmittance and FR at a chosen design wavelength.In a 17- layer structure, at the wavelength of 748 nm, FR wasincreased from -2.6 deg/µm to -6.3 deg/µmat a smallreduction in transmittance from 69% to 58% as compared to asingle-layer BIG film of equivalent thickness. In contrast tothick BIG films, the MOPCs did not crack. We were first toreport preparation of all-garnet MOPCs and second toexperimentally demonstrate the MOPC principle inmagneto-optical garnets.</p>

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.