Ferrihydrite (FHYD), a nanocrystalline material has long been described as a poorly crystalline disordered mineral mainly due to its small crystal size which is typically 2−6 𝑛𝑚. The three-dimensional structure of the mineral has long been described by a multi-phase structural model that consists of Fe3+ only in octahedral (Oh) coordination. In this model ferrihydrite is described as a mixture of two major phases (akaganeite/goethite-like f-phase and feroxyhite-like d-phase) and a minor ultradispersed nanohematite phase. This model has been recently challenged and a new, single-phase model was proposed, having a basic structural motif closely related to the Baker-Figgs δ-Keggin cluster and is isostructural with the mineral akdalaite, Al10O14(OH)2. In its ideal form, the proposed new structure of FHYD consist of 80 % Oh and 20 % tetrahedral (Td) Fe3+ polyhedra which can be adequately described by a single-domain model with the hexagonal spacegroup 𝑃63𝑚𝑐 and unit cell dimensions 𝑎=5.95 Å and 𝑐=9.06 Å. In this study, nanoparticles of 2-line FHYD (FHYD2), 2-line FHYD deposited onto SiO2 (FHYD2/SiO2) and 6-line FHYD (FHYD6) synthesised using rapid hydrolysis of Fe(NO3)3.9H2O solutions were characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Mössbauer spectroscopy (MS) as well as magnetization and magnetic susceptibility measurements. The coordination environment of iron atoms in the structure of FHYD was investigated using TEM and MS. The thermal transformation of FHYD nanoparticles was monitored through changes in the magnetization as a function of temperature and the reduction behaviour in hydrogen environment was studied using temperature programmed reduction (TPR), in-situ XRD and MS. Electron diffraction, TEM/ scanning TEM (STEM) imaging, and electron energy loss (EELS) measurements were carried out on three different microscopes viz. JEOL JEM-2100 LaB6 TEM, aberration corrected Schottky-FEG JEOL JEM-ARM200F HRTEM and cold-FEG Zeiss SESAM TEM. EELS studies were concentrated mainly on the iron 𝐿-edge of FHYD and iron oxides reference spectra with well known crystal structures. The iron oxide Fe 𝐿-edge is usually characterized by two intense sharp peaks termed “white lines”. The fine structures introduced by the crystal field effect on the 𝐿- edge contain information that is highly specific to the Fe3+ site symmetry.

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This study of ATR-IR involved taking spectra of various silicate minerals in powder samples, finding similarities and differences in nature, and locating various bands and intensities of absorption bands for identification and classification purposes. This study is limited to 4000-300 cm-1 with major emphasis on absorptions in the 2000-300 cm-1 region.

No description available.

Considered the testudine that has been most kept in captivity as a pet due to its extensive illegal trade, Chelonoidis carbonaria species (tortoise-piranga or red-leg-tortoise) is widely distributed in South America and Brazil . The objective was to measure the changes in protein compounds, metabolites, minerals, electrolytes and serum enzyme in Chelonoidis carbonaria held captive using analytical methods routinely used in clinical laboratories, as this dosages are laboratory tests used in veterinary medical clinic for the important contribution that provide diagnosis and prognosis of metabolic changes that affect these animals. For this, used were 25 specimens from C. Carbonaria. Was performed on each animal both sexes, Blood collection Serum for subsequent biochemical analysis. Analyses were processed in automatic analyzer (Flexor XL). It was observed that the results of the serum biochemical constituents C. carbonaria evaluated to show no significant differences in mean observed for other species Testudines, the differences being observed probably due to the difference managements, diet and normal physiological variations different species. There were no significant differences between males and females for the studied parameters and the values obtained for glucose levels in venous blood obtained by enzymatic colorimetric method (GVE) and digital glucometer (GVG). Analytical techniques routinely employed for biochemical tests appear to be suitable for determining the biochemical profiles of these animals with the exception of gamma glutamyltransferase (GGT) and creatine kinase enzyme (CK) and creatine kinase MB (CK-MB) showed wide variations of standard deviations. The results of this study can contribute to the interpretation of biochemical parameters of tortoises as well as support other studies that seek to reference values for the species. / Considerada o Testudine que mais tem sido mantido em cativeiro como animal de estimação devido a seu amplo comércio ilegal, a espécie Chelonoidis carbonaria (jabuti-piranga ou jabuti-das-patas-vermelhas) encontra-se amplamente distribuída na América do Sul e no Brasil. Objetivou-se mensurar as variações de constituintes proteicos, metabolitos, minerais, eletrólitos e enzimáticos séricos em Chelonoidis carbonaria mantidos em cativeiro utilizando métodos analíticos rotineiramente empregados em laboratórios de análises clinicas, pois estas dosagens são exames complementares empregados na clínica médica veterinária pelo importante contributo que oferecem ao diagnóstico e prognóstico de alterações metabólicas que acometem esses animais. Para isso, foram utilizados 25 espécimes de C. carbonaria. Foi realizada, em cada animal de ambos os sexos, a colheita sanguínea para posterior análise bioquímica sérica. As análises foram processadas em analisador automático (Flexor XL). Observou-se que os resultados dos constituintes bioquímicos séricos avaliados para C. carbonaria não apresentam expressivas diferenças das médias observadas para outras espécies de Testudines, sendo as diferenças observadas provavelmente devido a diferença de manejos, dieta e variações fisiológicas normais diferentes espécie. Não houve diferenças significativas entre machos e fêmeas para os parâmetros estudados e para os valores obtidos para os níveis de glicose em sangue venoso obtidos pelo método enzimático colorimétrico (GVE) e glicosímetro digital (GVG). Técnicas analíticas rotineiramente empregadas para exames bioquímicos parecem ser adequados para determinação dos perfis bioquímicos destes animais com exceção da gama glutamiltransferase (GGT) e as enzimas creatina quinase (CK) e creatina quinase MB (CK-MB) apresentaram grandes variações dos desvios padrão. Os resultados obtidos neste estudo podem contribuir com a interpretação dos parâmetros bioquímicos de jabutis bem como subsidiar outros estudos que busquem valores de referências para a espécie. / Mestre em Ciências Veterinárias