47 resultados para Tin mines and mining


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Complete albinism is a rare phenomenon that occurs in all vertebrate groups. In bats, albinism has been recorded in several species but this information has not previously been reviewed in detail nor has there been an analysis of its importance. In this study, cases of albinism from the literature are checked and new cases are presented. Complete albinism in bats is documented in eight families, 38 species, and at least 64 individuals (47.4% female female and 52.6% males; n = 38). of these, 39 individuals were observed and/or captured in sheltered roosts, such as caves (51.3%), mines and galleries (20.5%), buildings (17.9%), and hollow-trees and bird boxes (7.7%). Only one albino bat (2.6%) was captured in an external roost (foliage). This individual is the fruit bat, Artibeus planirostris, which is recorded here for the first time. Information on four additional cases of albino individuals of the common vampire bat, Desmodus rotundus, is also presented. It is suggested that sheltered roosts favour survival of albino bars, offering protection against sunlight, water loss, and visually hunting predators.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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O processo pirometalúrgico convencional para a produção de chumbo metálico é comparado com dois novos processos ambientalmente não agressivos: o eletrohidrometalúrgico e fusão alcalina. O processo eletrohidrometalúrgico consiste em reduzir o tamanho das partículas dos compostos de chumbo e lixiviar os mesmos com uma solução ácida de fluoborato férrico. Neste ponto, o chumbo é dissolvido com os íons férricos sendo reduzidos a íons ferrosos. A solução resultante da lixiviação é bombeada para os compartimentos catódicos de uma célula eletrolítica de diafragma nos quais o chumbo metálico é depositado em catodos de aço inoxidável numa forma compacta e pura. A solução que é empobrecida em íons Pb2+ é então enviada aos compartimentos anódicos da mesma célula onde, nas superfícies de anodos ocorre a oxidação dos íons ferrosos a férricos, que retornam ao estágio de lixiviação. O processo de fusão alcalina consiste em se juntar soda cáustica fundida, enxofre e compostos de chumbo num reator a uma temperatura entre 600 °C e 700 °C. Como um resultado chumbo metálico é obtido juntamente com sais fundidos de sódio, sulfetos metálicos e borra. O fundido é processado, resultando em borra, sulfetos metálicos, soda cáustica e enxofre. Estes dois últimos retornam para o reator. Ambos os processos permitem a recuperação de metais como antimônio, estanho, enxofre e prata, que em processo convencional são perdidos na escória. Esses novos processos são ambientalmente corretos sem poluições severas de Pb e SO2. O chumbo metálico obtido é mais puro que aquele do processo convencional.

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In the present work, 199 patients with leprosy who underwent autopsy between 1970 and 1986 were retrospectively studied to determine the prevalence, types, clinical characteristics, and etiologic factors of renal lesions (RLs) in leprosy. Patients were divided into two groups: 144 patients with RLs (RL+) and 55 patients without RLs (RL-), RLs observed in 72% of the autopsied patients were amyloidosis (AMY) in 61 patients (31%), glomerulonephritis (GN) in 29 patients (14%), nephrosclerosis (NPS) in 22 patients (11%), tubulointerstitial nephritis (TIN) in 18 patients (9%), granuloma in 2 patients (1%), and other lesions in 12 patients (6%), AMY occurred most frequently in patients with lepromatous leprosy (36%; nonlepromatous leprosy, 5%; P < 0.01), recurrent erythema nodosum leprosum (33%; P < 0.02), and trophic ulcers (27%; 0.05 < P < 0.10), Ninety-seven percent of AMY was found in patients with lepromatous leprosy, 88% showed recurrent trophic ulcers, and 76% presented with erythema nodosum leprosum, NPS was found in older patients with arterial hypertension, neoplastic diseases, infectious diseases, and vasculitis associated with GN, Most patients with AMY presented with proteinuria (95%) and renal failure (88%), the most frequent causes of death were renal failure in patients with AMY (57%), infectious diseases in patients with GN (41%) and TIN (45%), and cardiovascular diseases in patients with NPS (41%), No difference in survival rates was observed among RL- patients and those with AMY, GN, NPS, or TIN. (C) 2001 by the National Kidney Foundation, Inc.

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Agricultural and mining activities are directly related to changes in natural landscapes. From the perspective of anthropogenic geomorphology supported by general systems theory, this research has developed, in order to identify and analyze changes in the land use, mainly from agriculture and the exploitation of clay, and its implications in the hydro-geomorphological characteristics in the Santa Gertrudes Stream watershed (SP). This area is within the context of the Ceramic Pole Santa Gertrudes (SP), which besides its importance as a supplier of raw material, is characterized as the largest center of international reference in ceramic tiles on the American continent. For this purpose, we made land use and geomorphology maps of two scenarios, corresponding to the years 1962 and 2006, which allowed the identification of changes caused by human activities on the landforms of the area, such as the increase in area of parcels intended for mining activity, which went from 3.1% to occupy 19% of the catchment area of the respective period and that, among other changes, gave rise to new forms of relief as, for example, in levels of pit mining abrupt and smooth. The results indicate that the main features of representative of human changes in relief are represented for opening of large clay mining pits and agricultural activities, which intensified the denudation and sedimentation processes in the Santa Gertrudes Stream watershed.

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SrSnO3, a perovskite-type complex oxide, was synthesized by the modified Pechini method using two different precursors, tin chloride and metallic tin. The first one is already traditional in the literature and it claims about 30 days, only for the cleaning of tin citrate aiming at the elimination of the chloride. The second route was developed by our research group and saves time, taking 6 h to complete the synthesis of the resin. The results show that SrSnO3 obtained from the metallic tin show a higher short range order, leading to a band gap value higher than those reported in the literature, besides a meaningful reduction in the formation of SrCO 3, as compared to the one obtained from tin chloride.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Geociências e Meio Ambiente - IGCE

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Pós-graduação em Geologia Regional - IGCE

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Civil - FEIS