Jarosite pseudomorph formation from arsenopyrite oxidation using Acidithiobacillus ferrooxidans

In this work, the oxidizing action of a native strain type A. ferrooxidans on a sulphide containing a predominance of arsenopyrite and pyrite has been evaluated. Incubation of the A. ferrooxidans strain in flasks containing 200 mL of T&K medium with the ore (particle size of 106 mu m) at pulp density 8% (w/v) at 35 degrees C on a rotary shaker at 200 rpm resulted in preferential oxidation of the arsenopyrite and the mobilization of 88% of the arsenic in 25 days. Mineralogical characterization of the residue after biooxidation was carried out with FTIR. XRD and SEM/XEDS techniques. An in situ oxidation of the arsenopyrite is suggested on the basis of the frequent appearance of jarosite pseudomorph replacing arsenopyrite, in which the transformations Fe(2+) -> Fe(3+), S(-2) -> S(+6) and As(-1) -> As(+3) -> As(+5) occur for the most part without formation of soluble intermediates, resulting in a type of jarosite that typically contains high concentrations of arsenic (type A-jarosite). However, during pyrite oxidation, dissolution of the constituent Fe and S predominates, which is evidenced by corrosion of pyrite particles with formation of pits, generating a type of jarosite with high quantities of K (type B-jarosite). Lastly, a third type of jarosite (type C-jarosite) also precipitated forming a thin film that covered the grains of pyrite principally. (C) 2010 Elsevier B.V. All rights reserved.

Morphological Characterization of the Testicular Cells and Seminiferous Epithelium Cycle in Six Species of Neotropical Bats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Situação vacinal infantil e características individuais e familiares do interior de São Paulo

The aim of this study was to describe and analyze individual and family characteristics of children and those of health services, as well as their relationship with the immunization status for different kinds of vaccines and doses. Three sources of information were used: records from the Municipal Health Information System, immunization charts, and interviews using closed-ended questions. The families interviewed still had one or two growing children; caretakers were usually young unemployed mothers with easy access to health services. Around 30% of them were not instructed on the vaccine being given, its reactions or when to return for the next shot. The greatest levels of tardiness occurred with the vaccines against measles (6.3%) and Haemophilus influenzae B (4.2%). It was possible to observe that tardiness or absence of vaccinations seem to have a stronger relationship with service characteristics than with population characteristics.

Preparação e caracterização inicial de complexo de inclusão entre nitrofurazona e 2-hidroxipropil-β-ciclodextrina

Nitrofurazone (NF), 5-nitro-2-furaldehyde semicarbazone, a broad-spectrum antibiotic, has reported toxic effects and low solubility in water. It would be of great interest to form inclusion complexes between NF and a cyclodextrin, to develop more effective and safer antibiotic formulations. This paper focuses on the preparation of inclusion complexes of NF with 2-hydroxypropyl-β- cyclodextrin (HP-β-CD) and their initial characterization by evaluating rates of complex formation, photostability, solubility isotherms, release rate profiles, stoichiometry of the complexes and their morphology, as revealed by scanning electron microscopy. The kinetic tests of complex formation revealed that 17,3 h is enough for stabilization of the NF-cyclodextrin complex. The solubility isotherm studies showed that the isotherm changes from type A to type B, as a function of temperature. The photostability experiments showed that the insertion of the NF in the HP-β-CD cavity protects the drug from photodecomposition. The release kinetic tests showed that the profile of NF release from the complex is altered by the presence of HP-β-CD in the medium. A Job's plot indicated that the stoichiometry of the complex was 1:1 NF:HP-β-CD. The scanning electron micrographs showed changes in the crystal structure of NF in the complex. This study focused on the physicochemical properties of drug-delivery formulations that could potentially be developed into a novel type of therapy with NF.

Efeitos do canto de anúncio e do tamanho corporal no espaçamento entre machos em agregações de Dendropsophus nanus (Anura, Hylidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do tamanho dos grânulos nas características estruturais e físico-químicas do amido de trigo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise perceptivo-auditiva e acústica da voz em crianças de 4 a 12 anos com obstrução nasal crônica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Podisus nigrispinus (Dallas, 1851) (Hemiptera: Pentatomidae): efeito do alimento e da temperatura de armazenamento de ovos no desenvolvimento do inseto

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ocorrência e caracterização molecular de Cryptosporidium spp. em cordeiros na Região de Araçatuba-SP-Brasil: avaliação da transferência da imunidade passiva

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Células T reguladoras em cães com linfoma multicêntrico: quantificação, em sangue periférico, no momento do diagnóstico e após a etapa inicial do tratamento quimioterápico

Pós-graduação em Medicina Veterinária - FCAV

Comparação dos efeitos da hidrocinesioterapia e do treinamento físico realizado no solo em hipertensas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Epidemiologia molecular aplicada ao monitoramaento de estirpes de Staphylococcus aureus envolvidas em casos de mastite bovina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ocorrência de diferentes tipos de canais acessórios cavo inter-radiculares em molares de humanos. Estudo histológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variação morfofisiológica das castas em algumas espécies de vespas enxameantes neotropicais (Vespidae: Epiponini) ao longo do ciclo colonial

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Biodiesel de buriti em trator: desempenho em função do tipo de diesel e da proporção de mistura na operação de preparo do solo

Pós-graduação em Agronomia (Ciência do Solo) - FCAV