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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
371

Estudo da variacao da area especifica, da acidez superficial e do volume do poro de alguns bauxitos brasileiros em funcao da temperatura de ativacao

SILVA FILHO, JOAQUIM G. da 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:31:46Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:06Z (GMT). No. of bitstreams: 1 12893.pdf: 1625501 bytes, checksum: fe39dd92498184bf046e7732940f5cc2 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP
372

Previsao de demanda de transporte de materiais radioativos para o programa nuclear brasileiro e os aspectos de seguranca

MELDONIAN, NELSON L. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:29:01Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:14Z (GMT). No. of bitstreams: 1 01010.pdf: 16336682 bytes, checksum: fb7f780f24753f31fb96810fce4c3a14 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
373

Aplicacao da correlacao angular perturbada ao estudo da perovskita de CdTiO-3 impurificada com Hf

SOUZA, SYLVIO D. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:30:14Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:14Z (GMT). No. of bitstreams: 1 00418.pdf: 926606 bytes, checksum: a75368bd1ec19098eb6adbb843ab0886 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Energia Atomica - IEA
374

Aplicacao da analise por ativacao para a determinacao de alguns elementos em amostras de cassiterita

ARMELIN, MARIA J.A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:26:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:49Z (GMT). No. of bitstreams: 1 12891.pdf: 1261412 bytes, checksum: 22d81b21c8b5536ef9c962a801aed517 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
375

Metodologia isotopica Pb/Pb. Aplicacao aos migmatitos e rochas

BABINSKI, MARLY 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:32:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:04Z (GMT). No. of bitstreams: 1 03260.pdf: 1951792 bytes, checksum: df5a7d0d061d521c988a4035eb497536 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
376

Efeitos de dois níveis de sulfato de cobre e cobre metionina no metabolismo e oxidação de lipídios em ovinos / Effects of two levels of copper sulphate and copper-methionine on metabolism and lipid oxidation in sheep

Cármen Maria Lucas Pedro Garrine 27 November 2013 (has links)
O cobre está associado ao metabolismo de lipídios, sendo bastante importante na redução do colesterol, e à estabilidade oxidativa da carne, por fazer parte de algumas enzimas antioxidantes. Atributos esses que tornam cada vez mais interessante a pesquisa do uso do mineral em várias espécies, com vista a melhorar a qualidade de vida dos consumidores, uma vez que se pode reduzir o risco de doenças cardiovasculares e câncer, assim como dos fornecedores de carne pelo possível aumento da vida de prateleira e das características organolépticas do produto. Desse modo, o objetivo deste estudo foi determinar o efeito da suplementação com dois níveis de sulfato de cobre e cobre metionina sobre o metabolismo de lipídios e colesterol e estabilidade oxidativa lipídica da carne em cordeiros Merino x Texel. Para o efeito, um experimento foi conduzindo na FZEA, USP de Pirassununga utilizando 40 cordeiros Merino x Texel, que foram distribuídos aleatoriamente em 5 tratamentos, totalizando 8 animais em cada. Os animais foram alojados em gaiolas individualizadas para estudo de metabolismo e o experimento teve a duração de 120 dias. Os tratamentos usados foram: controle, sem adição; suplementação com 10 ou 30 mg de Cu/Kg de MS na forma de sulfato de Cobre; suplementação com 10 ou 30 mg de Cu/Kg de MS na forma de cobre metionina. Foram feitas biópsias do fígado dos animais no tempo zero para análise de cobre e colhidas amostras de sangue para dosagem sérica de Cu. Nos dias 0, 28 e 56 foram colhidas amostras de sague para dosagem de colesterol total, HDL e triglicerídeos. Ao final do experimento, os animais foram abatidos para colheita de amostras de fígado para determinação dos teores de Cu; dosagem das enzimas glutationa reduzida (GSH), glutationa oxidada (GSSH), atividade das enzimas antioxidantes, superóxido dismutase (SOD) e glutationa peroxidase (GP-x) e determinação dos níveis das substâncias reativas ao ácido tiobarbitúrico (TBARS). No momento da desossa foi medida a espessura da gordura subcutânea entre a 12ª e 13ª costela. No mesmo momento, foram colhidas amostras do músculo longissimus para dosagem de colesterol total, análise de perfil de ácidos graxos e TBARS. O músculo longissimus esquerdo foi retirado e congelado a vácuo por 12 meses, após os quais amostras foram colhidas e expostas no expositor refrigerado a 4°C para estudo da estabilidade oxidativa lipídica que foi acompanhada pelos valores de TBARS nos dias 0, 3 e 6. A suplementação com cobre proporcionou maior acúmulo de Cu no fígado (P<0,05), porém, a concentração do elemento no músculo não foi alterada pela suplementação. Não houve diferença significativa (P>0,05) para espessura de gordura subcutânea, concentrações séricas de triglicerídeos, colesterol total, HDL e LDL entre os tratamentos controle e suplementação com cobre, independentemente da fonte. A suplementação com cobre alterou o perfil de ácidos graxos da carne (P<0,05), com aumento na proporção do ácido láurico (C12:0) do grupo controle comparado com os demais tratamentos (P<0,05). Houve redução da concentração de colesterol no músculo longissimus (P<0,05) dos cordeiros suplementados com Cu em relação ao grupo controle, acompanhado de redução (P<0,05) da concentração da GSH e aumento da GSSG no fígado (P<0,05). Não houve efeito da suplementação para níveis de TBARS no fígado (P>0,05), mas houve efeito significativo (P<0,10) no longissimus colhido no momento da desossa. A suplementação com Cu não teve efeito sobre os valores de TBARS para as amostras dispostas na vida de prateleira, porém, houve aumento linear desses valores ao longo do tempo. A suplementação com Cu aumentou a atividade da SOD e GP-x (P<0,05) no fígado. Estes resultados sugerem que o cobre pode ser usado para melhorar a qualidade de carne sem afetar a sua estabilidade oxidativa lipídica. / Copper is associated with lipid metabolism, becoming very important in reducing cholesterol and oxidative stability of meat, because it is part of some antioxidant enzymes. These attributes make interesting the research of this mineral in various animal species to improve the quality life of consumers, since they can reduce the risk of cardiovascular diseases and cancers, as well as of the suppliers of the meat due to the possibility of increase the shelf life and organoleptic characteristics. So the aim of this study was to determine the effect of two levels of copper sulphate and copper methionine on lipid and cholesterol metabolism and lipid oxidative stability in meat of Merino x Texel lambs. For that, an experiment was conducted in the Faculty of Animal Science and Food Engineering, University of São Paulo, at the Pirassununga Campus using forty male lambs, Merino x Texel, randomly distributed into 5 treatments groups of 8 animals each. The animals were housed in individualized cages for the study of sheep metabolism, for a period of 120 days. Treatments used were: control, without addition of Cu (Co); 10 or 30 mg of Cu/kg of DM in the form of Cu sulphate (CuSO4); 10 or 30 mg of Cu/kg of DM in the form of copper methionine (Cu-methionine). Liver biopsies were carried out in all animals to determine initial hepatic Cu level. On day 0, 28 and 56 of the experiment blood were collected for analysis of total cholesterol, HDL cholesterol (HDL) and triglycerides. At the end of the experiment, animals were humanely slaughtered and liver samples were collected for later for analysis of Cu, reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione peroxidase (GP-x), superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS). After 24 hours of cooling, left carcasses halves were sawed into two parts between the 12th and the 13th rib to obtain the fat thickness (EGSC). During sawing muscle sample from m. longissimus were collected for determination of cholesterol, fatty acids profiles and TBARS. At the same time, m. longissimus muscle entire was collected and frozen under vacuum for 12 months for study of oxidative stability. After that, steaks of m. longissimus were collected and exposed to \"display life\" (DL) (4°C) to study oxidative stability which was accompanied by TBARS values on days 0, 3 and 6. The copper supplementation resulted in higher concentration and accumulation of Cu in the liver (P<0.05), however, the concentration of Cu in muscle was not altered by supplementation (P>0.05). There was no significant effect (P>0.05) for fat thickness, serum triglycerides, total cholesterol, HDL and LDL between control and copper supplementation regardless of the source. The copper supplementation altered the fatty acid profile of the meat (P<0.05), with an increase in the proportion of lauric acid (C12: 0) in the control group compared with the other treatments (P<0.05). Copper supplementation reduced cholesterol concentration in m. longissimus (P<0.05) in supplemented lambs compared to the control group, this reduction was accompanied by reduction concentrations of GSH (P<0.05) and increasing of oxidized glutathione (GSSG) in the liver (P<0.05). There was no effect of Cu supplementation for TBARS in the liver however, there was significant effect on m. longissimus collected during sawing (P<0.10). There was no effect of Cu supplementation for TBARS in the m. longissimus exposed in the \"Display Life after 12 months vacuum freezing (P>0.05), but there was a linear increase in TBARS values during this period. Cu supplementation increased the activity of SOD and GP-x (P<0.05) in the liver. These results suggest that copper can be used to improve meat quality without affecting the oxidative stability.
377

Caracterização espectro-mineralogica e aspectos sobre a genese de materias-primas ceramicas classicas do Brasil : estudos de caso em depositos de pirofillita, talco e caulinita / Spectral-mineralogical characterization and genetic aspects of classic Brazilian ceramic materials : case studies in pyrophillite, talc and kaolinite deposits

Senna, Juliano Alves de 12 August 2018 (has links)
Orientador: Carlos Roberto de Souza Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-12T09:20:32Z (GMT). No. of bitstreams: 1 Senna_JulianoAlvesde_D.pdf: 63737232 bytes, checksum: 420aa968e8b724cb3159057231ad922a (MD5) Previous issue date: 2008 / Resumo: Matérias primas cerâmicas (MP.C) naturais são materiais geológicos que exercem papel fundamental na economia de países mais desenvolvidos. Entretanto, no Brasil há uma tendência histórica em preterir investimentos na prospecção e explotação destes bens não metálicos em relação aos metálicos. Em função disso, os métodos de lavra até hoje utilizados são empíricos e o controle de qualidade precário, salvo alguns . poucos depósitos administrados por grandes grupos mineradores. Neste sentido, há uma clara lacuna tecnológica a ser preenchida neste setor no Brasil. A Espectroscopia de Reflectância (ER), baseada na faixa do visível e infravermelho de ondas curtas (0.4-2.5um), é uma ferramenta fundamental do sensoriamento remoto e eficaz na detecção de óxidos e hidróxidos de ferro e alumínio, carbonatos e filossilicatos. Seu uso potencial para caracterização espectro-mineral de MPCs é significativo, visto que não requer nenhuma preparação, é uma técnica rápida e de simples operacionalidade, e as análises podem ser feitas diretamente in situo Considerando as complexidades envolvidas nesta caracterização, os objetivos desta pesquisa foram: (i) avaliar a eficácia da ER em separar as faciologias dos minérios, (ii) propor modelos espectro mineralógicos dos depósitos, (iii) analisar as possibilidades de mapeamento dos minerais associados às jazidas, e (iv) determinar parâmetros que auxiliem na classificação dos minérios para uso industrial. Neste contexto, três importantes depósitos (peculiares e representativos metalotectos brasileiros) de MPCs foram escolhidos para investigação: (i) Pirofillita (Agalmatolito, para cerâmica refratária) em Mateus Leme (MG), (ii) Talco (para revestimentos cerâmicos) em Ponta Grossa (PR) e Caulinita (ball-clay, para louça sanitária e porcelana) em São Simão (SP). Em todos os depósitos, os materiais foram cuidadosamente classificados, seja quanto à composição mineral ou a aplicação industrial, com detecção dos principais minerais presentes e de espécimes ainda desconhecidas nos depósitos. Da mesma forma, o mapeamento interativo auxiliado por dados multiespectrais ASTER e espectros selecionados após a classificação, permitiu o reconhecimento espacial das abundâncias, concentrações e misturas minerais existentes nos depósitos. O sucesso da ER em caracterizar MPCs demonstrou a viabilidade.da técnica: (i) para o reconhecimento de fácies litológicas e fases minerais, (ii) para a investigação dos materiais in situ por equipamentos portáteis, (iii) para dar suporte ao planejamento de lavra de curto e longo prazo, e (iv) para aplicações multidisciplinares nos estágios pré e sinindustrialização. Desta forma, a pesquisa contemplou o objetivo de caracterizar os mais clássicos tipos de MPCs brasileiras, possibilitando o desenvolvimento de novas técnicas de explotação adequada a cada caso, considerando um controle de qualidade ideal. Adicionalmente, a análise integrada dos dados permitiu avanços no entendimento da geometria e gênese desses depósitos, os quais poderão ser utilizados em etapas futuras de prospecção dessas commodities. / Abstract: Raw ceramic materials (CM) are geological resources that play a fundamental role in the economy ofhigh1y developed countries. However, in Brazil there is a historical tendency in disregarding investments in the prospecting and exploitation of these non-metallic commodities, in contrast to the metallic equivalents. As a function of that, current mining approaches are yet too empirical and the quality control precarious, exception made to a few deposits administered by large mining companies. fu this sense, there has been a c1ear technological gap to be filled in this sector in Brazil. Reflectance Spectroscopy (RE), based on visible, near-inftared and shortwave inftared wayelengths, is a key remote sensing tool and effective in detecting Fe- and Al-bearing oxides and hydroxides, carbonates 8l1d phyllosilicates. Its potential use to the spectral-mineralogical characterization of CMs is significant, as it is a quick,operational, nondestructive technique that requires no sample preparation and that can be use for measuring materials in situo Considering the complexities involved in this characteyization, the objectives of this research were: (i) to evaluate the efficacy of ER in separating ores fades and associated rocks; (ii) to propose spectral-mineralogical models for the deposits, (iii) to analyze the possibility to map minerals associated to the deposits, and (iv) to determine parameters that might help in the c1assification of ores employed by the industry. In this context, three important deposits (peculiar and representative Brazilian metalotects) of ceramic materials were chosen for the investigation: (i) Pyrophyllite (agalmatolite, for reftactory pottery) in Mateus Leme (Minas Gerais), (ii) Ta1c (for ceramic coverings)in Ponta Grossa (PR) and, (iii) Kaolinite (ball-c1ay, for sanitaryware and china pottery) in São Simão (SP). In all of these deposits, the materials were carefu11y c1assified as regards both mineral composition and industrial applications, with detection of both foremost minerals and specimens yet unknown in the deposits. Similarly, the interactive mapping provided by the c1assification of ASTER multispectral data based on selected spectral endmembers permitted the spatial recognition of the abundances, concentrations and existing mineral mixtures in the deposits. The success of the ER in characterizing CMs showed the feasibility of the technique (i) for the recognition of lithologic facies and mineral phases, (ii) for the analysis of geologic materials in situ by portable instruments, (iii) to provide support to the planning of short- to longterm mining and, (iv) for multidisciplinary applications during pre- to contemporary-industrialization stages. Consequently, the main objective of the overall research to characterize a multitude of c1assic Brazilian CMs was achieved, allowing the development of new methods for quality controlled exploitation of distinct ceramic ores. Additionally, the integrated analysis of the data permitted advancements in the understanding of the geometry and genesis of those deposits, which could be utilized in future phases of prospecting of those commodities. / Doutorado / Metalogenese / Doutor em Ciências
378

Characterization and an investigation on ceramic properties of selected continental clay materials

Ekosse Ekosse, Georges-Ivo 02 June 2014 (has links)
M.Tech. (Extraction Metallurgy) / Please refer to full text to view abstract
379

Mineralogy and geochemistry of the fine and the clay fractions of till in northern Finland

Pulkkinen, P. (Pekka) 17 September 2004 (has links)
Abstract The mineralogy and geochemistry of the fine and clay fractions of till in different moraine types and in different bedrock areas in northern Finland have been studied. A total of 250 till samples from 140 test pits were studied mineralogically and geochemically. X-ray diffraction, differential thermal and thermogravimetric analyses, transmission electron microscopy, X-ray fluorescence and atomic absorption spectrometry were used as analytical methods. In the clay fraction of till quartz, plagioclase, microcline and amphibole are the primary minerals occurring. The clay minerals proper include vermiculite, chlorite, illite, swelling-lattice vermiculite and mixed-layer clay minerals. Kaolinite occurs most abundantly in the clay fractions of till in the Kittilä, Jerisjärvi, Kaaresuvanto and Pulju areas. In the clay fraction of Kittilä and Jerisjärvi illite is dioctahedral type, but in their of other study areas both di- and trioctahedral types occur. Kaolinite and dioctahedral illite are evidence of the mixing of the weathered bedrock material into the till matrix. In the fine fraction of till most abundant minerals are primary minerals and clayminerals are in a minor role. In the clay fraction of till the content of primary minerals are at higher and secondary minerals are at lower level in the Granitic and Archaean gneiss areas than in the Greenstone Belt, Svecokarelian schists and gneiss and Granulite areas. Amphibole, microcline and plagioclase occur in very low amounts or are totally destroyed by chemical weathering in the clay fraction of the till in the Kittilä area. The mineral composition of fine and clay fractions in the tills of northern Inari gives an indication that there occur much more mafic volcanites than is known today. The mineralogical compositions of fine fraction of the tills correlates quite well with the underlying bedrock in all study areas, but clay fraction does not. Geochemical results are in accordance with the mineralogical composition of both fractions. In the fine fraction of the till Si, Ca and Na contents are higher than in the clay fraction. Clay fraction is enriched in Al, Fe, Mg, K and trace elements as compared to the fine fraction. Present study material points out that the distribution of chemical elements in the clay fraction of the till does not correlate with the composition of the underlying bedrock, but fine fraction does so with a few exceptions. The chemical composition of till in Kaaresuvanto and Inari does not fully correspond to the composition of the underlying bedrock as known today. In northern Inari and Kittilä the results give an indication that there are more mafic volcanites and/or sulphide mineralizations occurring in these areas than is known at the present time. The most important factors controlling the mineralogical and geochemical composition of the fine and clay fractions of the tills in northern Finland are the composition of the bedrock and the possible occurrence of an old weathering crust. The final grain size composition of the tills and consequently the quantitative proportions of the different minerals are often related to the last glacial quarrying and sorting processes; therefore the mineralogical composition of the tills is to a certain extent bound also to the respective moraine type.
380

Economic geology of sulphide nickel deposits

Harrison, P A January 1983 (has links)
From Chapter 1: It has been a long standing belief that many nickel sulphide ores are derivatives of magmatic processes in ultramafic and mafic rocks, and that they segregate from these magmas as immiscible sulphide droplets which are then concentrated into an orebody by gravitational settling either during intrusion or extrusion, or during the early stages of crystallization of the magma (Naldrett, 1981). Some geologists however, have suggested alternative mechanisms to explain the concentration of nickeliferous sulphides in the mafic and ultramafic hosts. These include hydrothermal replacement (Fleet, 1977), exhalative volcanic processes (Lusk, 1976), or major metamorphic upgrading of low grade, initially magmatic deposits (Barrett et al., 1977). It is not the purpose of this study to verify or disprove these hypotheses, but in so far as the initial concentration of sulphides in most deposits is concerned, these effects are relatively unimportant (Naldrett, 1981). The nickel sulphide ores associated with these mafic and ultramafic host rocks, invariably consist of nickeliferous pyrrhotite as the dominant phase, together with lesser, but variable, amounts of magnetite, pentlandite, chalcopyrite, cubanite, and platinum group elements (Reynolds, 1982).

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