O carvão mineral é responsável por 40 % da eletricidade produzida mundialmente e por 44 % das emissões de CO2, decorrentes de seu uso para fins energéticos. O CO2 está entre os principais gases causadores do efeito estufa, por isso as pesquisas em captura e armazenamento se concentram nesse gás. A tecnologia de combustão de carvão em atmosfera de oxicombustão tem sido estudada como alternativa devido à facilidade de capturar o CO2 resultante da reação e poder armazená-lo. Assim, um dos objetivos deste estudo foi determinar os parâmetros cinéticos da reação de oxicombustão nas temperaturas de 600, 700, 740, 800 e 900 °C com concentrações de O2 em CO2 variando de 10 a 30 % (v/v). Os resultados obtidos para a energia de ativação foi 10 kJ.mol-1 e para o fator pré-exponencial 13,817 g.min-1.cm-2.atm-n. Como os carvões sul-brasileiros contém alto teor de cinzas seria interessante o beneficiamento desta matéria-prima a fim de reduzir seu teor de matéria mineral e poder utilizá-la para fins energéticos. Portanto, também foi objeto de estudo nesse trabalho, a remoção da matéria mineral de uma amostra de carvão mineral utilizando soluções de HF, HCl e HNO3 com concentração de 20 % em volume. Esse tratamento foi realizado utilizando carvão da mina de Candiota e carvão da mina do Leão II. Através de análise imediata, análise elementar, difração de raios-X (DRX), fluorescência de raios-X (FRX), infravermelho à transformada de Fourier (FTIR) e microscopia eletrônica de varredura (MEV) se observaram grandes alterações na estrutura dos carvões após a extração da matéria mineral com as lavagens ácidas, o que refletiu na temperatura de início da reação de Boudouard que teve acréscimo de 140 °C para o carvão do Leão II e 160 °C para o carvão de Candiota. Os carvões desmineralizados, com baixos teores de cinzas, foram submetidos novamente à reação de oxicombustão nas mesmas condições utilizadas anteriormente para determinação dos parâmetros cinéticos. Os valores obtidos para a energia de ativação e para o fator pré-exponencial, respectivamente, foram 56,46 kJ.mol-1 e 5,37.10³ g.min-1.cm-2atm-n para o carvão de Candiota. Para o carvão do Leão II, os valores encontrados foram 169,4 kJ.mol-1 e 7,06.1014 g.min-1.cm-2atm-n. As amostras desmineralizadas da mina de Candiota foram impregnadas com um metal alcalino, um metal de transição e um semi-metal, a fim de avaliar a reatividade dos mesmos em atmosfera de CO2. Foi observado que o metal alcalino é o metal que promove uma taxa de conversão do carvão em atmosfera de CO2 mais rápida, seguido das amostras impregnadas com o metal de transição e do semi-metal. Na amostra de carvão Run of Mine (ROM) há possivelmente a presença de alguns elementos que agem como inibidores e outros elementos que atuam como catalisadores da reação de gaseificação. / The mineral coal is responsible for 40 % of electricity world production and 44 % of CO2 emissions resulting from their use for energy purposes. The CO2 is one of the main gases causing the greenhouse effect, hence research on capture and storage is concentrated in this gas. Coal oxy-fuel combustion technology has been studied as an alternative due to the ease of fully capturing the CO2 resulting from combustion and can store it. Therefore, one of the objectives of this study was to determine the kinetics parameters of oxy-fuel combustion reaction at temperatures of 873, 973, 1073 and 1273 K with concentration of O2 in CO2 ranging from 10 to 30 % (v/v). The results obtained for the activation energy was 10 kJ.mol-1 and the pre-exponential factor 13.817 g.min-1.cm-2.atm-n. As the southern Brazilian coal has high ash content, beneficiation process the need in order to reduce its content of mineral matter and can use it for energy purposes. Therefore, too was the object of study in this paper, the removal of mineral matter from a coal sample using solutions of HF, HCl and HNO3 with concentration of 20 % by volume. This treatment was performed using Candiota coal and Leão II coal. Through immediate analysis, elemental analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were observed large changes in the structure of coals after extraction of the mineral matter with acid washes, which reflected the onset temperature of Boudouard reaction that was 140 °C in addition to the Leão II coal and 160 °C for Candiota coal. The demineralized coals, with low ash content, were subjected again to the oxy-fuel combustion reaction the same conditions previously used to determine the kinetic parameters. The values obtained for the activation energy and the pre-exponential factor, respectively, were 56.46 kJ.mol-1 and 5.37.10³ g.min-1.cm-2atm-n to Candiota coal. For Leão II coal the values were 169.4 kJ.mol-1 and 7.06.1014 g.min-1.cm-2atm-n. The demineralized samples of Candiota coal, were impregnated with an alkali metal, a transition metal and semi-metal in order to assess the reactivity in CO2 atmosphere. It was observed that the alkali metal is metal that promotes the conversion rate faster coal, followed by the samples impregnated with transition metal and semi-metal. In coal sample Run of Mine (ROM) there is possibly the presence of some elements which act as inhibitors and other elements that act as catalysts gasification reaction.

A Jazida de Mármore de Quixaba, no Piauí, era de economicidade controvertida para cantaria em vista do fraturamento do maciço e das impurezas da rocha aflorante. Investigações sobre a litologia, estrutura e geomorfologia da área mostraram que essas feições são notáveis nos afloramentos, com fortes expressões topográficas locais, enquanto que nas porções baixas do corpo de rochas carbonáticas ocorrem rochas maciças e puras. Neste trabalho são discutidos os condicionantes geológicos, petrológicos e geomorfológicos identificados e os critérios de prospecção e caracterização tecnológica aplicados ao desenvolvimento e aproveitamento da jazida. A grande variedade química de rochas, com propriedades físicas semelhantes, industrializadas e comercializadas por profissionais de formação geocientífica, tem motivado o uso de termos ambíguos que dificultam o cômputo de dados e a avaliação do desempenho econômico do setor das cantarias. Como contribuição ao estabelecimento de uma nomenclatura clara e precisa é apresentada uma classificação das rochas para a construção civil que correlaciona conceitos petrológicos, industriais e comerciais. Ainda à luz de poucos e esparços dados disponíveis, é feita uma análise do mercado nacional e internacional do mármore como pedra de cantaria. / not available

The objective of this study was to determine the effects of processing on sodium - potassium and calcium - phosphorus ratios in tuna canned in oil and in water, peanut butter, white and whole wheat flours. Mineral levels were determined by atomic absorption spectrophotometry in food samples at various stages in the production of these finished products. The average sodium - potassium ratios of the tuna samples were: 1.37 raw, 1.24 precooked, 1.87 canned in oil and 1.61 canned in water. Processing did not significantly effect sodium and potassium ratios in canned tuna. The average calcium - phosphorus ratios of the tuna samples were: 0.034 raw, 0.024 precooked, 0.034 canned in oil and 0.065 canned in water. The ratio of the canned in water meat was significantly effected by processing. The average sodium - potassium ratios of the peanut samples were: 0.034 raw, 0.043 roasted, 0.031 blanched and 0.781 peanut butter. The ratio of peanut butter was significantly greater than the ratios of the other peanut samples. The average calcium - phosphorus ratios of the peanut samples were: 0.148 raw, 0.121 roasted, 0.141 blanched and 0.128 peanut butter. These ratios were not significantly effected by processing. The average sodium - potassium ratio was 0.16 in white flours, 0.84 in whole wheat flour and 0.89 in the kernel. The average calcium - phosphorus ratio was 0.14 in white flours, 0.07 in whole wheat flour and 0.07 in the kernel. The ratios of the kernel and whole wheat flour were not significantly different. Processing significantly effected the ratios of the white flour. The preferred concentration of sodium chloride and a 1:1 sodium - potassium chloride mixture in white and whole wheat breads was also studied. Bread samples were made with 1.0%, 0.75% and 0.5% levels of both salt treatments. They were evaluated by an untrained flavor panel for overall desirability with a nine point hedonic scale. The judges preferred a sodium chloride white bread with a 7.0 sodium - potassium ratio, and a sodium chloride whole wheat bread with a 3.29 ratio. These ratios were both lower than those found in commercial products. White and whole wheat breads made with 0.75% sodium chloride were as acceptable as breads made with 1.0% 1:1 sodium - potassium chloride mixture. The sodium - potassium ratio of the salt mixture white bread was 1.20 and the ratio of the whole wheat bread was 0.91. The addition of salt to finished products for flavor had an effect on the sodium - potassium ratio of the foods studied. Also, reducing the amount of added salt to commercial breads and replacing some sodium chloride with potassium chloride were acceptable means of lowering the sodium - potassium ratios of white and whole wheat breads. / Graduation date: 1982

Cretaceous bauxite deposits from Hall and Veneer mines, Wilkinson County, Georgia are composed of kaolinite, gibbsite, goethite, anatase, nordstrandite and bohemite. Quartz and micas are absent in the samples. The presence of boehmite and goethite are evidence of intense weathering forming the bauxite deposits. The extremely high values of the Chemical Index of Alteration (CIA) which is over 99, and the low values of the alkali metals and alkali earth metals, support an intense weathering origin for the bauxite deposit. There is evidence of deposition in the mines based on the presence of pisoids in the bauxite samples and the composition of the parent materials, which vary markedly by the non-uniform TiO2/Al2O3 values which represent the accumulation of transported materials from contrasting source areas. Kaolin minerals were first produced by the hydrolytic weathering of aluminous sediments and then gibbsite was formed as early kaolin was desilicated.

Thesis (M.Sc.)(Earth Sciences)--University of Pretoria, 2005. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Development of peak bone mass during childhood to early adulthood has been considered as a major determinate of risk of fracture and osteoporosis later in life. The purpose of this project was to determine the impact of food and nutrient intake on bone from childhood to early adulthood using mixed longitudinal data from the University of Saskatchewan Pediatric Bone Mineral Accrual Study (PBMAS). <p>To determine the role of consumption of milk products and vegetable and fruit on the total body-bone mineral content (TB-BMC) accrual in boys and girls from childhood to late adolescence, seven-year longitudinal data were used. Using a multilevel modeling statistical approach containing major biological and environmental factors, vegetables and fruit intake, calcium intake and physical activity were significant independent environmental predictors of TB-BMC in boys. <p>Change in the pattern of beverage intake of adolescents as a major component of nutrition transition has aroused health concerns such as obesity, tooth decay, and inadequate bone accrual. Beverage consumption and its relationship with calcium intake of grade 9 students from 1991 to 2004 was evaluated. Percent contribution of milk to total beverage intake was significantly decreased in boys and girls. A significant negative association between milk intake and consumption of non-carbonated soft drinks was observed in both genders. In girls only, a significant negative trend in calcium intake was observed over time. <p>Milk products, specifically fluid milk, were the major source of dietary calcium from childhood to early adulthood in both genders. There was a substitution of fluid milk by cheese, a decrease in vegetable and fruit intake, and the low intake of vitamin D in young adults, specifically females. <p>The effect of food and nutrient intake, measured at young adult age and previously in peri-adolescence, on bone mass was investigated. In males, the intake of calcium from peri-adolescence to early adulthood was sustained, whereas in females, there was a significant decrease. Height, weight, protein intake, physical activity and gender were the significant predictors of bone measures only in young adults who had consistent calcium intake from peri-adolescence. Collectively, the results of this study present the bone protective nutrients and food groups from childhood to early adulthood in our cohort. The food choices and dietary habits of the cohort change by age, but not in the favour of bones, with females more at risk. To prevent risk of osteoporosis, there should be promotion of a healthy dietary plan, not a single food group or nutrient, accompanied with an adequate level of physical activity.

Development of peak bone mass during childhood to early adulthood has been considered as a major determinate of risk of fracture and osteoporosis later in life. The purpose of this project was to determine the impact of food and nutrient intake on bone from childhood to early adulthood using mixed longitudinal data from the University of Saskatchewan Pediatric Bone Mineral Accrual Study (PBMAS). <p>To determine the role of consumption of milk products and vegetable and fruit on the total body-bone mineral content (TB-BMC) accrual in boys and girls from childhood to late adolescence, seven-year longitudinal data were used. Using a multilevel modeling statistical approach containing major biological and environmental factors, vegetables and fruit intake, calcium intake and physical activity were significant independent environmental predictors of TB-BMC in boys. <p>Change in the pattern of beverage intake of adolescents as a major component of nutrition transition has aroused health concerns such as obesity, tooth decay, and inadequate bone accrual. Beverage consumption and its relationship with calcium intake of grade 9 students from 1991 to 2004 was evaluated. Percent contribution of milk to total beverage intake was significantly decreased in boys and girls. A significant negative association between milk intake and consumption of non-carbonated soft drinks was observed in both genders. In girls only, a significant negative trend in calcium intake was observed over time. <p>Milk products, specifically fluid milk, were the major source of dietary calcium from childhood to early adulthood in both genders. There was a substitution of fluid milk by cheese, a decrease in vegetable and fruit intake, and the low intake of vitamin D in young adults, specifically females. <p>The effect of food and nutrient intake, measured at young adult age and previously in peri-adolescence, on bone mass was investigated. In males, the intake of calcium from peri-adolescence to early adulthood was sustained, whereas in females, there was a significant decrease. Height, weight, protein intake, physical activity and gender were the significant predictors of bone measures only in young adults who had consistent calcium intake from peri-adolescence. Collectively, the results of this study present the bone protective nutrients and food groups from childhood to early adulthood in our cohort. The food choices and dietary habits of the cohort change by age, but not in the favour of bones, with females more at risk. To prevent risk of osteoporosis, there should be promotion of a healthy dietary plan, not a single food group or nutrient, accompanied with an adequate level of physical activity.

Two feeding trials were conducted to evaluate the effects of dietary phytic acid contents and removal of phytate from plant protein sources on growth and utilization of phosphorus, zinc and iron in juvenile cobia. In experimental I, test diets were formulated by adding phytic acid, 0, 5, 10, 15 and 20 g/kg diet to the basal diet that used fish meal and wheat gluten as the protein source. Juvenile cobia with an initial weight of 20g were fed the test diets for 8 weeks. No significant difference among fish groups was found in percent weight gain, feed conversion ratio, protein efficiency, net protein utilization and body composition. Dietary phytic acid level significantly affected zinc concentrations in body, vertebra, serum and feces. Body zinc concentration in fish fed diet containing 2% phytic acid was 10.2% lower than the control group. Vertebra and serum zinc concentrations decreased with increasing dietary phytic acid levels, vertebra zinc concentration in fish fed diet containing 2% phytic acid was 22.3% lower than the control group. The dietary phytic acid concentration was positively related to the fecal zinc concentration. In experimental II, nine isonitrogenous, isolipid and isocaloric diets were formulated including control diet that contained 421g/kg fish meal, and four test diets with fish meal protein in control diet being replaced by 40 or 50% with soybean meal or by 30% or 40% with canola meal respectively. Another four test diets used dephytinized soybean or canola meal after phytase treatments removed 90.9~94.6% of phytate. Juvenile cobia with an initial weight of 94g were fed the test diets for 8 weeks. Growth, feed conversion ratio, protein efficiency and net protein utilization of fish fed diets containing plant proteins were poorer than control group. Better weight gain, feed conversion ratio and net protein utilization were observed in those groups fed diets contained soybean meal rather than canola meal. Ash, phosphorus, zinc and iron contents of whole body and vertebra in cobia fed phytase-pretreated plant protein were not significantly different from groups of fish fed raw plant protein. In conclusion, dietary phytic acid reduced the zinc bioavailability. Performance of cobia as well as diet quality indicated that soybean meal as the better alternative protein source for fish meal than canola meal. Dephytinization had no positive effect on utilization of phosphorus, zinc and iron in juvenile cobia.

Thesis (M.A.)--University of Florida, 2006. / Title from title page of source document. Document formatted into pages; contains 174 pages. Includes vita. Includes bibliographical references.

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