Characterization of Ni-containing goethites by Mossbauer spectroscopy and other techniques

A set of goethite samples from the oxidized level of Vermelho Ni-lateritic deposit was investigated by TEM, XRD, TGA-DTA, FTIR and Mossbauer spectroscopy and compared to a series of synthetic goethite samples, with similar Ni content. Natural Ni-containing goethite presents poor crystallinity and does not incorporate more than about 4 mol% Ni. Natural goethite particles also contain significant amounts of Al and Cr (1.6 and 0.7 mol%, in average, respectively). The wavenumbers of the OH deformation vibration bands delta-OH (in-plane vibration) and lengthening gamma-OH (out of plane vibration) are coarsely negatively correlated with Ni content. The weight loss during the thermal analysis of synthetic samples shows a good linear relationship with Ni content, pointing to a proton uptake in order to compensate a possible charge imbalance due to a Ni2+ for Fe3+ substitution. The Mossbauer spectra of Ni-goethite present one sextet whose parameters are in agreement with those usually reported for goethite. The magnitude of the hyperfine field slightly decreases with increasing Ni, while the other parameters remain unchanged. These variations may be explained by Ni incorporation, but also by differences in the crystallinity. The effect of the low Ni concentration in our samples was a weak to medium correlation of the analytical signals with the Ni content in goethite, but when considered together, the results indicate that isomorphic substitution is occurring.1424173255957

Perfil dos casos novos de tuberculose notificados em Ribeirão Preto (SP) no período de 2000 a 2006 Profile of new cases of tuberculosis in Ribeirão Preto, São Paulo State, in the period of 2000 to 2006

A Organização Mundial de Saúde estima que um terço da população mundial encontra-se infectada pelo Mycobacterium tuberculosis, sendo que 8-9 milhões de pessoas desenvolvem a doença e, anualmente, 2 milhões vão a óbito por tuberculose, principalmente em países e regiões com condições socioeconômicas precárias. Este estudo descreve o perfil dos casos novos de tuberculose notificados no município de Ribeirão Preto (SP) no período de 2000 a 2006. Utilizou-se um desenho descritivo do tipo coorte. Para a coleta dos dados, foi utilizado o banco de dados Epi-Tb. A forma clínica predominante foi a pulmonar. Verificou-se que 71,7% dos doentes eram do sexo masculino e adultos jovens (20-39 anos). Em relação ao tipo de supervisão, observou-se aumento gradativo da forma supervisionada ao longo do período considerado, exceto no ano de 2003. A coinfecção Tb/HIV mostrou-se superior a 25%, sendo que 12,9% dos doentes não realizaram o teste anti-HIV. Quanto ao resultado de tratamento, a cura variou de 62,7% a 76,7%, a média do abandono foi de 4,3% e óbito por tuberculose foi de 3,9%. Os resultados apresentados contribuem para o conhecimento da situação epidemiológica da tuberculose ao longo dos anos, fornecendo subsídios à tomada de decisões relacionadas principalmente às ações de prevenção e controle da doença no município.<br>The World Health Organization estimates that one third of the world population is infected by the Mycobacterium tuberculosis, while 8-9 million of people develop the disease and 2 million die each year due to tuberculosis, especially in countries and regions with precarious socioeconomic conditions. This study describes the profile of new cases of Tuberculosis notified in Ribeirão Preto, São Paulo State, in the period between 2000 and 2006. A cohort descriptive design was used. The database Epi-Tb was used for the data collection. The clinical form predominant was pulmonary. It was verified that 71.7% of patients were male and young adults (20-39 years). Regarding the type of supervision, it was observed that the supervised form presented a progressive increase along the period considered, with exception of 2003. The Tb/HIV co-infection was superior to 25%, while 12.9% of the patients performed the test. Regarding the treatment result, cure varied from 62.7% to 76.7%, the abandonment mean was 4.3% and death by tuberculosis was 3.9%. The results presented contribute for the knowledge of the tuberculosis epidemiological situation along the years studied, providing support to decision making related to prevention actions and control of the disease in the municipality