This article aims at growing (0002) InN film on LiGaO2 substrate by chemical vapor deposition (CVD). High purity InCl3 and metallic indium were used to react with NH3 respectively to form InN. Different experimental condictions such as growth temperature and the reaction pressure were adopted and compared to grow a well crystalline structure and smooth InN thin film. After one hour reaction, InN deposits on LiGaO2 substrate. X-ray diffraction, scanning electron microscope, atomic force microscope, photoluminescence, and transmission electron microscope of the samples were measured to investigate the crystal orientation, crystal quality, surface morphology, and microstructure. Based on the result, we can get the best condiction to grow the InN thin film. Through the experimental results, it is found that InN can not be successfully grown by using metallic indium. Oppositely, it is not difficulty to form InN by using InCl3. After a series of attempts on experiments, the temperature of 600 ¢J and the pressure of 400 torr are found to be the best condiction to grow the InN thin films.

Ozone is a powerful oxidant which can be use for bacterial inactivation, deodorizing, and bleaching. In aquatic farms, it can improve larvae hatching and keep water quality under control. The primary object of this research is to investigate the influence of ozone solubility by the concentrations chloride¡]Cl-¡^and bromide¡]Br-¡^in seawater. The indigo colorimetric method was used to detect the variation of total residual oxidants¡]TROs¡^after ozonation. The bacteriocidal effects of ozone with added Cl- or Br- were tested on three common marine fish pathogens. The results showed that the ozone solubility in reverse osmosis¡]RO¡^treated water was about 2.3 mg/L, and rapidly decreased to 0.5 mg/L when ozonation stopped. The process of ozonation in seawater from start to equilibrium, the TROs concentration could reach 8.5 mg/L and then decreased slowly to a stable concentration of about 6 mg/L. When Cl- was added in RO water, the TROs concentration varied from 2 to 3.5 mg/L, and rapidly disappeared after stop ozonation. It was concluded that Cl- could not effectively increase ozone solubility in seawater. In contrast, adding Br- in RO water not only efficiently increased the solubility of ozone but also maintained the TROs concentrations after stop ozonation, and the TROs concentrations were proportional to the Br- concentrations. The same trends were also observed in seawater added with Br-. In the bacteriocidal effect of ozone, compare with pure seawater, adding of Br- in seawater could effectively reduce the TROs concentrations needed to completely inhibit each pathogen. Such practice may be extended to aquatic farms to eliminate or reduce the bacterial pathogens in seawater.

On-going research at Texas A&M University indicated that soil stabilization using calcium chloride filter cake along with Class F fly ash generates high strength. Previous studies were conducted with samples containing calcium chloride filter cake and both Class C fly ash and Class F fly ash. Mix design was fixed at 1.3% and 1.7% calcium chloride and 5% and 10% fly ash with crushed limestone base material. Throughout previous studies, recommended mix design was 1.7% calcium chloride filter cake with 10% Class F fly ash in crushed limestone base because Class F fly ash generates early high and durable strength. This research paper focused on the strength increase initiated by greater than 1.7% pure calcium chloride used with Class F fly ash in soil to verify the effectiveness and optimum ratio of calcium chloride and Class F fly ash in soil stabilization. Mix design was programmed at pure calcium chloride concentrations at 0% to 6% and Class F fly ash at 10 to 15%. Laboratory tests showed samples containing any calcium chloride concentration from 2% to 6% and Class F fly ash content from 10% to 15% obtained high early strength however, optimum moisture content, different mix design, and mineralogy deposit analysis are recommended to evaluate the role and the effectiveness of calcium chloride in soil stabilization because of the strength decreasing tendency of the samples containing calcium chloride after 56 days.

Thesis (Ph. D.)--University of Pittsburgh, 1915. / Vita.

Thesis (Ph. D.)--University of Chicago, Department of Chemistry, 2002. / Includes bibliographical references. Also available on the Internet.

published_or_final_version / Zoology / Master / Master of Philosophy

Chloride is a deleterious ionic species in cooling water systems because it is important in promoting corrosion. Chloride can be removed from cooling water by precipitation as calcium chloroaluminate using ultra-high lime with aluminum process (UHLA). The research program was conducted to study equilibrium characteristics and kinetics of chloride removal by UHLA process, study interactions between chloride and sulfate or silica, and develop a model for multicomponent removal by UHLA. Kinetics of chloride removal with UHLA was investigated. Chloride removal was found to be fast and therefore, removal kinetics should not be a limitation to applying the UHLA process. Equilibrium characteristics of chloride removal with UHLA were characterized. Good chloride removal was obtained at reasonable ranges of lime and aluminum doses. However, the stoichiometry of chloride removal with UHLA deviated from the theoretical stoichiometry of calcium chloroaluminate precipitation. Equilibrium modeling of experimental data and XRD analysis of precipitated solids indicated that this deviation was due to the formation of other solid phases such as tricalcium hydroxyaluminate and tetracalcium hydroxyaluminate. Effect of pH on chloride removal was characterized. Optimum pH for maximum chloride removal was pH 12 ± 0.2. Results of equilibrium experiments at different temperatures indicated that final chloride concentrations slightly increased when water temperature increased at temperatures below 40oC. However, at temperatures above 40oC, chloride concentration substantially increased with increasing water temperature. An equilibrium model was developed to describe chemical behavior of chloride removal from recycled cooling water using UHLA. Formation of a solid solution of calcium chloroaluminate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate was found to be the best mechanism to describe the chemical behavior of chloride removal with UHLA. Results of experiments that studied interactions between chloride and sulfate indicated that sulfate is preferentially removed over chloride. Final chloride concentration increased with increasing initial sulfate concentration. Silica was found to have only a small effect on chloride removal. The equilibrium model was modified in order to include sulfate and silica reactions along with chloride in UHLA process and it was able to accurately predict the chemical behavior of simultaneous removal of chloride, sulfate, and silica with UHLA.

No description available.

Soil salinity is a serious environmental stress threatening productivity of major crops worldwide. Among the various biotic and abiotic strategies that exist, transgenic technologies provide a promising avenue to reduce yield losses in crops under saline environments. Recently, transgenic technology involving the TMT gene encoding thiol methyltransferase enzyme has been suggested as an effective solution for engineering a chloride detoxification capability into a high value crops to improve tolerance against chloride ion toxicity under saline environments. This proposed mechanism, however, results in the emission of methyl chloride (CH3Cl) from plants, which has deleterious effects on stratospheric ozone. This study was performed to examine the relationship between salt tolerance and chloride volatilizing capacity of transgenic plants containing TMT gene as well as to explore the possibility of generating transgenic rice crop containing TMT gene for salinity tolerance. To achieve these objectives, transgenic tobacco plants containing TMT gene were grown in comparison with wild type tobacco plants under three levels of sodium chloride (NaCl) salinity (0, 100 and 200 mM), three levels of soil water content (40%, 60% and 80% of the field capacity) and their tolerance to NaCl and water stress was studied. Plant growth parameters recorded included plant height, number of leaves, leaf area, stem dry weight, leaf dry weight, root dry weight, plant dry biomass and root/shoot ratio. Similarly, both types of plants were exposed to five levels of NaCl concentrations (0, 50, 100, 150 and 200 mM) and three levels of soil water content (40%, 60% and 80% of the field capacity), and the quantity of CH3Cl emitted was recorded. Significant decrease in plants growth parameters of both types of plants were recorded upon exposure to salinity and water stress. Under 100 mM NaCl, however, transgenic plants showed better tolerance to salinity by suffering less reduction in growth parameters compared to wild type plants. Under 200 mM NaCl, growth of both types of plants was completely inhibited. The interactive effects of salinity and water stress were more pronounced in wild type plants than in transgenic plants. Results also showed that all engineered plants acquired an ability to efficiently transform chloride ion to CH3Cl, and the rate of such transformation was higher under greater NaCl and soil water content compared to lower NaCl concentrations and soil water content. In order to explore the possibility of generating a transgenic food crop using TMT gene, a hypothetical transgenic rice crop was grown over 27 million hectares of the saline coastal areas of south and southeast Asia and the possible emission of CH3Cl from such ecosystem was inferred based on the CH3Cl emission data obtained from transgenic tobacco plants. The estimates showed that the possible CH3Cl emission from such ecosystem would be 219.21 Gg which is equivalent to 5.36 % of the global atmospheric emissions of CH3Cl.

Partial replacement of cement by metakaolin is known to improve concrete durability, by refining the pore structure to improve fluid transport properties and by reducing the alkalinity of the pore solution to make ASR less problematic. A gap exists in the literature as to the salt scaling performance and magnesium sulphate performance of metakaolin concrete. 10 concrete mixes were cast at w/cm ratios of 0.4 and 0.5. In addition to metakaolin, grade 80 slag was used as well as CSA GU cement. All replacement levels were tested for setting properties, compressive strength, drying shrinkage, sulphate resistance, salt scaling, ASR mitigation and chloride diffusion characteristics according to the appropriate CSA and ASTM standards. It was found that metakaolin showed better performance in magnesium sulphate solutions than slag and that metakaolin concretes attained strength and other durability properties much faster than mixes without it. Keywords: metakaolin, ASR, sulphate, magnesium, scaling, setting, diffusion