Background: Data regarding Hepatitis B and C viruses (HBV and HCV) prevalence among military personnel in Brazil are lacking, but the work-related risk of exposure can be high. The objective of this study was to estimate the seroprevalence of HBV and HCV and the risk factors associated to HBV exposure among Brazilian military personnel.Methods: A cross-sectional study was conducted and included 433 male military adults aged 18-25 years old working in Rio de Janeiro during October 2013. All individuals completed a questionnaire to assess their risk of exposure and provided a blood sample to HBV and HCV testing.Results: None of the participants presented HBsAg or anti-HBc IgM, 18 (4.1%) were positive for total anti-HBc, 247 (57.0%) were positive for anti-HBs, and 3 (0.7%) were anti-HCV reactive. The majority of military personnel with past HBV infection (anti-HBc reactive) and HBV immunity (anti-HBs reactive) had a history of prior dental procedures (88.9% and 77.3%), consumption of alcohol at least once a week (50% and 55.9%), and practiced oral sex (61.1% and 58.3%, respectively). In addition, anti-HBc positivity was common among individuals with a history of surgery (44.4%) and practice of anal sex (50%). At univariate analysis, age group was associated to anti-HBc and anti-HBs positivity.Conclusions: Low rates of HBV and HCV infection were observed among Brazilian military personnel in comparison to the general Brazilian population. HBV immunity rates were relatively low indicating the need for vaccination campaigns in this group.

A técnica de difração de raios X de alta resolução foi utilizada para a caracterização estrutural da solução sólida, formada a partir de nitreto de silício (Si3N4), denominada alfa-SiAlON. Cerâmicas de alfa-SiAlON foram produzidas utilizando aditivos à base de AlN-Y2O3 ou AlN-CRE2O3. O óxido misto, CRE2O3, é uma solução sólida formada por Y2O3 e óxidos de terras raras. Os resultados mostraram a formação de solução sólida nos materiais sinterizados e não foi detectada segregação de óxidos utilizados como aditivos de sinterização. A similaridade das propriedades estruturais, morfológicas e mecânicas entre SiAlONs produzidos com aditivos contendo Y2O3 ou CRE2O3 indica a possibilidade de substituição do Y2O3 por CRE2O3 na produção de alfa-SiAlONs por um custo mais baixo.

Solid solutions formed by silicon nitride, known as SiAlONs, were prepared using different additives, such as AlN-Y2O3 or AlN-CRE2O3. The mixed oxide CRE2O3 is a solid solution formed by Y2O3 and rare-earth oxides. The high-resolution X-ray diffraction results of the sintered material show the formation of a solid solution. No segregation of second phases was detected. The similarities of structural, morphological and mechanical properties among SiAlONs prepared from different additives containing Y2O3 or CRE2O3 show the possibility of the production of alpha-SiAlON using CRE2O3 rather than Y2O3 as additive at lower cost.

Amostras de carbeto de silício (SiC) foram sinterizadas com dois aditivos: AlN-Y2O3 ou AlN-CRE2O3. CRE2O3 é um óxido misto formado por Y2O3 e óxidos de terras raras. A estrutura cristalina das fases nas amostras foi analisada através de difração de raios X de alta resolução com fonte de luz síncrotron. Os resultados de refinamento do óxido misto pelo método de Rietveld mostraram a formação de uma solução sólida. Em ambas as amostras preparadas usando AlN- Y2O3 ou AlN- CRE2O3 foram detectados politipos 3C (fase beta) e 6H (fase alfa). Os resultados estruturais e microestruturais das duas amostras mostraram-se similares. Esta é uma indicação da viabilidade do uso de CRE2O3 em substituição a Y2O3 como aditivo para a obtenção de materiais cerâmicos densos.

Silicon carbide (SiC) was sintered using two different additives: AlN-Y2O3 or AlN-CRE2O3. CRE2O3 is a mixed oxide formed by Y2O3 and rare-earth oxides. The crystalline structures of the phases were analyzed by high-resolution X-ray diffraction using synchrotron light source. The results of the Rietveld refinement of the mixed oxide show a solid solution formation. In both silicon carbide samples prepared using AlN-Y2O3 or AlN-CRE2O3 3C (beta-phase) and 6H (alpha-phase) polytypes were found. The structural and microstructural results for both samples were similar. This is an indication of the viability of the use of CRE2O3 in substitution for Y2O3 as additive to obtain dense materials.

In this work several structural and chemical properties of self-assembled InAs islands grown on GaAs(001) are studied using surface x-ray scattering with synchrotron radiation. The technique of x-ray diffraction under grazing incidence condition was employed to differentiate coherent and incoherent islands. We used a model of a strained pyramidal island to interpret the x-ray results and correlate size and strain-state of these islands. The degree of GaAs interdiffusion in the islands was inferred from the variation of volume of the unit cell. The Poisson's ratio of the two materials involved establishes a limit of tetragonal distortion for this material. Any variation in this distortion is associated with the presence of Ga inside the islands.