Master of Science / Department of Agronomy / Ramasamy Perumal / Tesfaye Tesso / Grain mold (GM) is an important biotic constraint limiting yield and market value of sorghum grains. It results in kernel discoloration and deterioration. Such kernels have reduced seed viability, low food and feed quality. Breeding for grain mold resistance is challenging because of the complex nature of host-pathogen-environment interactions. This complex task could be made simpler by utilizing molecular markers. Utilization of marker resources may help to find genomic regions associated with grain mold resistance. In this study, three sets of field and laboratory based experiments were performed which will help in finding potential grain mold pathogens responsible for kernel deterioration in the studied environment and search for genotypes with better kernel quality and grain mold resistance. In the first part of the study, in vitro screening of 44 grain mold resistant sorghum genotypes developed and released by Texas A & M AgriLife Research. This study was aimed at identifying sources resistance to grain mold infection through laboratory screening. The result revealed that genotypes Tx3371, Tx3373, Tx3374, Tx3376, Tx3407, Tx3400, and Tx3402 were have high level of resistance and were identified as potential sources of grain mold resistance as each showed minimal fungal infection and higher grain quality traits. The second experiment was performed to optimize surface sterilization protocol for the extraction of fungal pathogens from the kernel surface (pericarp) and to study the effect of bleach percentage and time period on pathogen extraction. Seven treatments using sterilized double distilled water (0 % bleach (v/v)) and different bleach (NaOCl) concentrations (2.5, 5, 7.5, 10, 12.5 and 15 %) were used with a time interval of 2.5, 5, 7.5 and 10 min. Optimized surface sterilization in the range of 7.5 to 15 % bleach (v/v) for 7.5 to 10 min resulted least contamination and fungal genera isolation from the surface of the kernel. The third study was aimed at characterizing genotypes (sorghum association panel) for grain mold pathogen F. thapsinum and by using genome wide association (GWA) tool in order to find genomic regions associated with grain mold resistance. We studied the effect of different agronomic and panicle architecture traits on grain mold incidence and severity. Effects of grain mold on kernel quality traits were also studied. We reported two loci associated with grain mold resistance. Based on first year field screening results, 46 genotypes having grain mold ratings 1-5 (1 = < 1% panicle kernel molded; 5 = > 50% panicle kernel molded) were selected for a detailed study aimed at understanding grain mold x fungal pathogen interactions to physical and chemical kernel traits. Seed germination test, vigor index, and tetrazolium viability test were performed to study effect of grain mold infection on kernel viability and vigor. Alternaria, Fusarium thapsinum, F. verticillioides and F. proliferatum were the main fungal genera isolated from bisected kernels. Based on two year screening, SC623, SC67, SC621, SC947 and SC1494 were most resistant based on both PGMR and TGMR rating while SC370, SC833, SC1484, and SC1077 showed the most susceptible reaction and this was consistent for individual location analysis. SC309, SC213, SC833, SC971 and SC1047 are genotypes having identified loci for grain mold resistance.

The subject of soil absorption is an old one, dating back to before 1850. The nature of soil absorption has been, and still is, a puzzle, in spite of the vast amount of work that has been done in the last few years. Two theories have been held as the cause of the absorption. The first is that the absorption is chemical, the compounds being changed into insoluble ones by double decomposition. The second is that the salts or radicals are physically held, that is, adsorbed by the soil particles. These theories have been held separately and combined.

While the market for “green” building materials has been expanding rapidly, no rigorous framework exists for evaluating the chemical and biological reactivity of these building materials. The objective of this research was to assess the ozone reactivity, primary and secondary VOC emission rates and mold resistance of selected green building materials. Two different sets of experiments were conducted. The first set focused on reactive consumption of ozone by ten common green materials. A screening assessment of secondary emissions of C6 and greater carbonyls was also completed for selected green materials. The second set was completed to evaluate the relative resistance of selected green building materials and their conventional analogs to surface fungal growth in moist interior environments. Ozone reactivity varied considerably between test materials. The ozone deposition velocity for inorganic ceiling tiles, for example, was two times higher than cabinetry materials and approximately fifty times higher than UV-coated bamboo. Experimental results were used as input to a simple mass balance model which predicted that the ratio of indoor to outdoor ozone concentrations was not significantly affected by green building materials. The green materials used in this study emitted less primary and secondary VOCs than did their non-green counterparts, although the difference was not significant and the material sample set was relatively small. Also, the green materials tested were not prone to either less or more mold growth than their conventional counterparts. Instead, materials composed of organic materials with high equilibrium moisture contents (EMC) were more prone to mold growth than inorganic materials with low EMC. Perlite-based (inorganic) ceiling tiles that consumed relatively large amounts of ozone without corresponding by-product formation were also resistant to mold growth. Such findings should facilitate the selection of future green building materials, both explicitly and by defining a protocol for future testing of green materials. / text

Estágio realizado na Qimonda Portugal, S.A. e orientado pelo Doutor Rui Batista / Tese de mestrado integrado. Engenharia Metalúrgica e de Materiais. Faculdade de Engenharia. Universidade do Porto. 2008

Since 1998, the United States Green Building Council, via the Leadership in Energy and Environmental Design (LEED) standards, has established the premiere set of guidelines for construction ethics from the standpoint of eco-friendliness and occupant safety and health in the U.S. and around the world. These guidelines are skyrocketing in use due in part to two reasons: · increased awareness of a need for reducing, reusing, and recycling in order to save resources and natural areas for future generations; and, · increased amount of time spent indoors in work places and homes. The LEED guidelines encourage sustainable and responsible use of land, water, energy, and materials, and promote a safe and healthy environment through use of innovative designs and technology. As part of the responsible use of materials, the LEED guidelines encourage the use of rapidly renewable materials such as cotton, straw, wool, and cork as insulation products. Although these products can be produced naturally and quickly from nature, they are also cellulose or carbohydrate based products. Cellulose and carbohydrate based materials are typically optimal food sources for mold in the presence of moisture, ironically destroying facilities and creating poor living and work environments. Samples of wool, cork, straw, and cotton--rapidly renewable materials used as exterior wall insulation products--were exposed to different moisture amounts in an encapsulated environment, representing the environment within a wall cavity when exposed to water from pipes, leaks, condensation and absorption, or from initial construction. The samples were monitored over time for mold growth. The data logged from the samples were analyzed to determine the degree of mold susceptibility of each material. In addition, samples with increased amounts of moisture were examined to determine increased promotion of mold growth. The results from this study showed that all of the above mentioned materials were highly susceptible to mold growth and that the moisture amount did not increase the rate of mold growth. Based on the data collected from this study, recommendations were made to review the current use of rapidly renewable and other cellulose and carbohydrate based materials in wall construction.

The exceptional physical, chemical, electric, and mechanical properties of ceramics, glass and diamond film make them receive much attention in high-tech industry. Although the electrochemical discharge machining (ECDM) can be used to process those materials, most ECDM are used for machining micro-holes and wire cutting. However, the application on the polishing aspect is still scarce in the literature. In this study, a high-precision dynamic electrical pitting tester with the electrolyte of KOH is employed to investigate the behavior of static electrochemical discharge in terms of supply voltage and gap distance between the steel ball and the diamond film. Furthermore, its machining characteristics are also analyzed. According to the current waveform, the I-V curve is plotted. Results show that the current value of glass is higher than that of diamond film and acrylic. This indicates that the glass is easily to be ionized. According to the observation on the surface of machined diamond film by using SEM, the machined status can be divided into four regimes. In the first regime, the supply voltage is less than 100V where the machined mark on the diamond film cannot be found. Hence, it is called non-machined regime. In the second regime, the supply voltage is in the range between 100 and 107V, where only very slight damage can be observed on the diamond film. Hence, it is called the fine machined regime. In the third regime, the supply voltage is in the range between 107 and 110V, where the machined status on the diamond film is unstable. Hence, it is called the transition regime. In the fourth regime, the supply voltage is larger than 110V, where the machined damage is very heavy. Hence, it is called the rough machined regime. At the supply voltage 105V with the gap less than 80£gm, the annular shape of the machined damage on the surface of the diamond film can be observed. However, when the gap is in the range between 80£gm and 95£gm, the annular shape of the machined damage disappears, but there is still slight damage at the asperity of the diamond film. When the gap is larger than 95£gm, the machined damage is invisible. Hence, the critical gap is defined as 95£gm for the supply voltage of 105V. At the supply voltage of 105V, the gap of 90£gm, and the machining time of 10 min, only the asperity of diamond film shows machined mark, but the surface is flatter. Therefore, it is possible to conduct the fine machining process by using ECDM on diamond film.

A sliding mode controller is proposed for controlling molten steel level in a mold of continuous casting machine in this thesis. The comparisons of dynamic response, control accuracy, and reaction to perturbation between proposed controller and PID controller currently used are also presented. A perturbation estimator is embedded in the sliding mode controller in order to enhance the robustness against model uncertainty, parameter variation, and external disturbance. The perturbation considered in this thesis includes variation of casting speed, variation of area of slide gate, time delay, variation of mold area, and Dead-Band etc.. In addition, the effects of adjusting the design parameter of the proposed controller on system¡¦s dynamics are also considered.

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3 pp. / A description of aphids, the damage they cause, their lifecycle, and management recommendations.

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