Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references. Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Hong Kong, 1995. / Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 1991.

Thesis (Ph. D.)--University of Hong Kong, 1998. / Includes bibliographical references.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 140-143).

Thesis (M.S.)--University of Wisconsin--Madison, 1980. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 55).

Doctor of Philosophy / Department of Agronomy / P. V. Vara Prasad / Increased ambient temperature and soil salinity seriously affect the productivity of wheat (Triticum aestivum L.) which is an important cereal second to rice as the main human food crop. However, wheat plant is most susceptible to high temperatures and salinity at booting and flowering stages. Several studies have documented the effects of individual stress like salinity and high temperature stress on wheat, nonetheless little is known about effects of combined salinity and high temperature at critical growth stages. Therefore, the objectives of this research were (i) to screen winter wheat germplasm for salinity tolerance at the germination stages and to determine seedling growth traits associated with salinity tolerance, (ii) to evaluate the independent and combined effects of high temperature and salinity on winter wheat genotypes at the booting stages through growth, physiological, biochemical, and yield traits, and (iii) to evaluate the independent and combined effects of high temperature and salinity on winter wheat genotypes at the flowering stages through growth, physiological, biochemical, and yield traits. In the first experiment, 292 winter wheat genotypes (winter wheat germplasm) was screened for salinity stress at germination stage under controlled environments. The seeds were subjected to three levels of salinity, 0, 60, and 120 mM NaCl to quantify the effects of salinity on seed germination and seedling growth. In the second experiment, controlled environment study was conducted to quantity the independent and combined high temperature and salinity stress effects on growth, physiological, biochemical, and yield traits of twelve winter wheat genotypes during booting stage. Plants were grown at 20/15 °C (daytime maximum/nighttime minimum) temperature with 16 h photoperiod. At booting stages, the plants were exposed to optimum (20/15 °C) or high temperature (35/20 °C) and without (0 mM NaCl) and with (60, and 120 mM) NaCl. In the third experiment, plants were exposed to optimum or high temperature and with and without NaCl levels at flowering stages. The temperature regime and salinity levels were same as experiment II. The duration of stress was 10 d and after the stress period the plants were brought to optimum temperature and irrigated with normal water (0 mM NaCl). The results indicated that, at 120 mM NaCl, the final germination percentage was decreased and the mean daily germination was delayed. Irrespective of the genotype, salinity stress significantly decreased the shoot and root length; seedling dry matter production, and seedling vigor. Based on the seedling vigor index, the genotype GAGE, OK04507, MTS0531, TASCOSA, ENDURANCE and GUYMON, were found to be most tolerant and CO04W320, 2174-05, CARSON, OK1070275, TX02A0252 and TX04M410211 were the most susceptible to salinity at germination stage. Combined stresses of high temperature and salinity decreased photosynthetic rate and grain yields. Based on grain yield, the genotype TASCOSA was found to be most tolerant (64 % decrease) to combined stresses, and AVALANCHE was the most susceptible to combined stresses (75 % decrease) at booting stages. Similarly, at flowering stage, TX04M410211 had greater tolerance to combined stresses (65 % decline) as compared to GAGE (83 % decline). In both experiments, tolerance was associated with higher spikelet number and seed set. In conclusion, there is genetic variability among winter wheat genotypes that can be used in breeding programs to improve winter wheat yield under combined high temperature and salinity stress conditions.

The wastewater treated at the Hopewell Regional Wastewater Treatment Facility (HRWTF) is very unique both because it is comprised of effluents of seven different industries in the area in addition to the domestic wastewater in the area, and because it reaches high temperatures in the basins, often above 45oC during the summer. Four different bench scale systems consisting of continuously stirred tank reactors (CSTRs) in series were operated during the summer of 1997 to quickly assess the feasibility of nitrifying and denitrifying the total flow at HRWTF down to a final effluent total nitrogen concentration of 10 mg-N/L or less. The four main treatment strategies tested were: aerobic/anoxic treatment of the final effluent of HRWTF at moderate temperatures (approximately 30oC); anaerobic/anoxic/aerobic (A2/O) treatment of the primary effluent of HRWTF at moderate temperatures; treatment of the effluent of one of the industries which had a high ammonia wastewater and which was originally believed to contain nitrification inhibitors; and fully aerobic treatment of the primary effluent of HRWTF at high temperatures (of approximately 40 to 45oC) with an activated sludge gradually acclimated to such temperatures over the course of two months. At the end of the study, a two-week high temperature study was conducted on the system which had been treating the secondary effluent all summer with the same activated sludge which was acclimated only to temperatures around 30oC. The fully aerobic high temperature system which had been nitrifying the primary effluent all summer was converted to a modified Lutzack-Ettinger (MLE) process at the end of the study to test whether the primary effluent could be denitrified as well as nitrified at high temperatures with the sludge acclimated to high temperatures. All four of the main treatment strategies demonstrated that nitrification and denitrification of either the total flow or the high ammonia side stream could be achieved down to the desired total nitrogen concentrations. The high temperature study conducted on the system which had been treating the secondary effluent all summer indicated that the sudden increase from approximately 30oC to approximately 40oC over a twenty-four hour period, similar to the sudden temperature increase which occurs every spring at HRWTF, quickly ends nitrification in a system not acclimated to high temperatures, while denitrification and COD removal is hardly affected by such a temperature change. While the nitrification performance of the gradually acclimated system treating the primary effluent at high temperatures was adequate, problems maintaining a consistent MLVSS or ETSS concentration suggested that the high temperatures seen in the basins at HRWTF are likely to make consistent treatment difficult. As a result of considering both capital cost requirements and quality of treatment, the bench scale testing suggested that the most likely candidates for successful treatment of the total flow down to desired total nitrogen concentrations would involve either the A2/O treatment of the primary effluent of HRWTF, possibly with the addition of a cooling tower, or A2/O treatment of the high ammonia side stream, possibly involving the dilution of the wastewater with one of the other flows sent to HRWTF. It was concluded that pilot scale evaluation of the two options was required for a final design decision, and pilot scale evaluation was being performed when this thesis was completed. / Master of Science

published_or_final_version / abstract / Physics / Doctoral / Doctor of Philosophy

Yeung, Him Ching = 以粉末混合方法及夾心樣品方法製作的硼化鎂的特性研究 / 楊謙靖. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / Yeung, Him Ching = Yi fen mo hun he fang fa ji jia xin yang pin fang fa zhi zuo de peng hua mei de te xing yan jiu / Yang Qianjing. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgments --- p.v / Table of contents --- p.vi / List of table captions --- p.viii / List of figure captions --- p.ix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Superconductors --- p.1 / Chapter 1.1.1 --- Classifications --- p.1 / Chapter 1.1.2 --- Conventional versus unconventional --- p.2 / Chapter 1.1.3 --- Type I and Type II superconductors --- p.4 / Chapter 1.1.4 --- Critical current Jc and the Bean´ةs Model --- p.5 / Chapter 1.2 --- Magnesium diboride --- p.8 / Chapter 1.2.1 --- Structure --- p.8 / Chapter 1.2.2 --- Physical properties --- p.8 / Chapter 1.2.3 --- Chemical properties --- p.9 / Chapter 1.2.4 --- Conduction mechanisms --- p.9 / Chapter 1.2.5 --- Fabrication methods --- p.9 / Chapter 1.3 --- Objectives of this work --- p.10 / References --- p.12 / Figures --- p.14 / Chapter Chapter 2 --- Methodology and instrumentation --- p.17 / Chapter 2.1 --- Experimental procedures --- p.17 / Chapter 2.2 --- Samples preparation --- p.17 / Chapter 2.2.1 --- Powder mixing approach --- p.17 / Chapter 2.2.2 --- Sandwich structure approach --- p.18 / Chapter 2.3 --- Samples fabrication --- p.18 / Chapter 2.4 --- Determination of compositions --- p.18 / Chapter 2.5 --- Characterization --- p.19 / Chapter 2.5.1 --- X-ray diffractometry (XRD) --- p.19 / Chapter 2.5.2 --- Microstructural analysis --- p.20 / Chapter 2.5.3 --- Magnetic measurements --- p.20 / Chapter 2.5.3.1 --- Setup for Jc measurements --- p.21 / Reference --- p.22 / Figures --- p.23 / Chapter Chapter 3 --- Powder mixing approach --- p.26 / Chapter 3.1 --- Results --- p.26 / Chapter 3.1.1 --- XRD results --- p.26 / Chapter 3.1.2 --- Compositions --- p.27 / Chapter 3.1.3 --- SEM results --- p.28 / Chapter 3.1.3.1 --- Sample sintered at 600°C --- p.28 / Chapter 3.1.3.2 --- Samples sintered at 700°C and 800°C --- p.28 / Chapter 3.1.3.3 --- Sample sintered at 900°C --- p.29 / Chapter 3.1.3.4 --- Sample sintered at 1000°C --- p.29 / Chapter 3.1.3.5 --- Sample sintered at 1050°C --- p.29 / Chapter 3.1.4 --- VSM results --- p.30 / Chapter 3.1.4.1 --- Tc measurements --- p.30 / Chapter 3.1.4.2 --- Hysteresis loops --- p.31 / Chapter 3.1.5 --- Jc measurements --- p.31 / Chapter 3.1.5.1 --- Direct measurement --- p.31 / Chapter 3.1.5.2 --- The Bean´ةs Model --- p.32 / Chapter 3.2 --- Discussions --- p.32 / Chapter 3.3 --- Summary --- p.35 / References --- p.36 / Figures --- p.37 / Tables --- p.47 / Chapter Chapter 4 --- Sandwich structure approach --- p.49 / Chapter 4.1 --- Results --- p.49 / Chapter 4.1.1 --- SEM results --- p.49 / Chapter 4.1.1.1 --- Surface of the Mg disk --- p.49 / Chapter 4.1.1.2 --- Inner region of the Mg disk --- p.50 / Chapter 4.1.2 --- XRD results --- p.50 / Chapter 4.1.2.1 --- Surface of the Mg disk --- p.50 / Chapter 4.1.2.2 --- Inner region of the Mg disk --- p.51 / Chapter 4.1.3 --- VSM results --- p.51 / Chapter 4.1.3.1 --- Tc measurement --- p.51 / Chapter 4.1.3.2 --- Hysteresis loops --- p.52 / Chapter 4.2 --- Discussions --- p.52 / Chapter 4.3 --- Summary --- p.54 / Reference --- p.54 / Figures --- p.55 / Tables --- p.61 / Chapter Chapter 5 --- Growth Mechanism --- p.62 / Chapter 5.1 --- Introduction --- p.62 / Chapter 5.2 --- Brief summary of results --- p.62 / Chapter 5.2.1 --- Powder mixing approach --- p.62 / Chapter 5.2.2 --- Sandwich structure approach --- p.63 / Chapter 5.3 --- Formation of the MgB2 platelets --- p.63 / Chapter 5.4 --- Size of the MgB2 platelets --- p.67 / Chapter 5.5 --- Summary --- p.68 / References --- p.69 / Figures --- p.70 / Tables --- p.75 / Chapter Chapter 6 --- Conclusions and suggestions of future work --- p.76 / Chapter 6.1 --- Summary --- p.76 / Chapter 6.2 --- Future work --- p.77 / Appendix 1 --- p.79 / Appendix 2 --- p.81