The effects of small amounts (up to 5 wt.%) of scandia- and ceria-stabilized zirconia on the electrical conductivity, and the elastic modulus and hardness of yttria-stabilized zirconia were investigated by impedance spectroscopy and nanoindentation tests, respectively. The main purpose of this work was to obtain solid electrolyte compounds with improved properties compared to those of the base materials. Solid electrolytes compounds were prepared by solid-state reaction synthesis with sintering at 1450 ºC for 4 h. All prepared compounds exhibit a cubic fluorite-type structure. The microstructure of the compounds consists of polygonal grains with low (< 2%) porosity. The mean grain size estimated by the intercept method was 5 ± 1 μm. The electrical conductivity of the compound ceramics is lower than that of the base material. Addition of scandia-stabilized zirconia is found to exert a beneficial effect on the matrix by increasing the elastic modulus, achieving 221 MPa for 5 wt.% of the additive.

Resumo Aqui, nós fornecemos novos registros de ocorrência de Scinax nasicus (Cope, 1862) para o estado do Rio Grande do Sul, Sul do Brasil. Todos os novos registros aqui fornecidos estão localizados na metade sul do estado. Além disso, nós fornecemos o primeiro registro para a espécie na zona costeira brasileira. Esses registros melhoram consideravelmente o nosso conhecimento sobre a distribuição da espécie no Sul do Brasil.

Abstract Herein, we provide new occurrence records of Scinax nasicus (Cope, 1862) for the state of Rio Grande do Sul, Southern Brazil. All new records here provide are located on Southern half of the state. Besides this, we provide the first record for species in Brazilian coastal zone. Those records improve considerably our knowledge regarding species distribution in Southern Brazil.

A perovskita CaCu3Ti4O12 foi consolidada pela técnica se sinterização assistida por campo elétrico. Foi investigada a influência do tempo e da temperatura de sinterização na estrutura cristalina, na microestrutura e nas propriedades dielétricas da cerâmica policristalina. As amostras foram sinterizadas entre 750 e 930 °C, por tempos de 1 a 8 min. Os pós foram calcinados a 900 °C durante 18 h. As pastilhas foram caracterizadas por difração de raios X, microscopia eletrônica de varredura e por espectroscopia de impedância. O padrão da difração de raios X apresenta a estrutura do tipo perovskita e o parâmetro de rede calculado é de 7,40 Å. A densidade hidrostática aumenta com o aumento do tempo e da temperatura de sinterização. A observação das imagens do microscópio eletrônico de varredura revelam uma microestrutura heterogênea para todas as amostras. As perdas dielétricas são inferiores aos valores apresentados por outras técnicas de consolidação. A permissividade dielétrica é aproximadamente 10³ a 1 kHz. O aumento do tempo e da temperatura de sinterização torna as amostras friáveis.

Polycrystalline CaCu3Ti4O12 ceramics were prepared by the field-assisted sintering technique. The effects of the dwell time and temperature on structural, microstructural and dielectric properties of CaCu3Ti4O12 ceramics have been investigated. Powder mixtures were calcined at 900 ºC for 18 h before consolidation. The dwell temperatures and times range between 750 and 930 ºC and 1 to 8 min, respectively. Sintered pellets were characterized by X-ray diffraction, scanning electron microscopy and impedance spectroscopy. X-ray diffraction patterns show evidences of a single-phase perovskite-type structure and the calculated lattice parameter is 7.40 Å. The hydrostatic density increases slightly with increasing dwell time and temperature. Scanning electron microscopy observations revealed a heterogeneous microstructure for all samples. The dielectric loss remains constant over a wide temperature range. The obtained permittivity is approximately 10³ at 1 kHz. The increase of the dwell temperature was found to produce a brittle ceramic.

Introducción: Se ha demostrado ampliamente que el genotipo F del virus de la hepatitis B (VHB) es dominante en nuestra población Amerindia. Recientemente, nosotros identificamos que en los pacientes infectados por VHB habitantes no migratorios de áreas urbanas venezolanas prevalece también el genotipo F. Objetivo: Determinar los genotipos del VHB en portadores crónicos urbanos migratorios y compararlos con el grupo no migratorio. Material y Métodos: Se investigaron 136 portadores crónicos del VHB, 110 no inmigrantes y 26 inmigrantes de origen asiático. Se evaluaron antígeno eHB y anti-eHB y los genotipos del VHB, este último mediante PCR. Resultados: En los 110 pacientes urbanos venezolanos persistió la elevada frecuencia del genotipo F (95%) con 3 casos coinfectados, 2 por genotipos A+F y 1 caso con genotipos E+F. Interesantemente, 2 casos demostraron genotipo D del VHB. Hepatitis crónica B (HCB) antígeno-e positivo fue diagnosticada en 83 pacientes (80,6%) mientras 20 casos (19,4%) presentaron HCB antígeno-e negativo. En los pacientes asiáticos infectados con un solo genotipo se identificó el C en 11 casos, el B en 4 pacientes, el F en 3 y, en 1 caso, genotipo D. Se demostró coinfección entre estos diferentes genotipos, incluyendo un caso coinfectado con genotipo E. El genotipo F se encontró coinfectando a 4 pacientes, 2 de ellos con genotipo C. Doce casos presentaron HCB antígeno e positivo y 14 pacientes HCB antígeno e negativo. De los pacientes infectados con genotipo C, 7 de ellos (54%), incluyendo los 2 coinfectados con genotipo F, presentaron HCB antígeno-e negativo. Conclusión: Es notoria la elevada circulación del genotipo F del VHB en nuestras áreas urbanas. La distinta evolución de la HCB descrita para genotipo F y, la identificación de otros genotipos diferentes al F en áreas urbanas sugiere que, independientemente del origen geográfico del paciente, la inclusión de los genotipos del VHB debiera considerarse pauta en el manejo de la HCB en Venezuela.

Introduction: It has been widely demonstrated that the genotype F of hepatitis B virus (HBV) is dominant in our Amerindian population. Recently, we identified that genotype F is prevalent in HBV non-migratory infected patients living in urban areas. Objective: To determine the genotypes of HBV in migratory chronic carriers compared to non-migratory population. Material and Methods: We investigated 136 chronic HBV carriers, 110 non-immigrants and 26 immigrants of Asian origin. We assessed hepatitis B e-antigen and antibody and HBV genotypes, the latter using PCR. Results: High prevalence (95%) of genotype F persisted among 110 Venezuelan urban patients, with 3 co-infected patients, 2 with genotypes A+F and 1 case with E+F. Interestingly, 2 cases showed HBV genotype D. Chronic hepatitis B (CHB) e-antigen positive was diagnosed in 83 patients (80.6%) while 20 cases (19.4%) showed CHB e-antigen negative. In Asian patients infected with one sole genotype, C was identified in 11 cases, B in 4 patients, F in 3, and in 1 case, genotype D. Co-infection was demonstrated among these different genotypes, including one case co-infected with genotype E. Genotype F was found in 4 co-infected patients, 2 with genotype C. Twelve cases had CHB e-antigen positive and 14 CHB e-antigen negative. From patients infected with genotype C, 7 of them (54%), including 2 co-infected with genotype F, demonstrated CHB e-antigen negative. Conclusion: It is remarkable the high circulation of HBV genotype F in our urban areas. However, given the distinct outcome described in CHB genotype F and the identification of other genotypes rather than F in urban areas, suggests that inclusion of HBV genotypes in Venezuela, should be considered standard in the management of CHB regardless the patient’s geographical origin.

A resposta imune celular foi estudada em pacientes com infecção recente ou crônica por Schistosoma mansoni. Células mononucleares do sangue periférico pré cultivadas reagiram significantemente a antígenos do verme adulto (SAWA) do S. mansoni quando comparadas à preparação contendo células frescas. A adição de soro autólogo às células pré-cultivadas resultou em inibição da reação frente a SAWA ou antígenos de memória; o mesmo efeito foi notado quando os soros de pacientes foram adicionados a culturas de células alogênicas obtidas de indivíduos normais. A subpopulação CD4 foi a principal população celular respondedora a SAWA, sendo que esta reatividade foi intensamente suprimida na presença de preparações purificadas contendo monócitos-macrófagos. Estes resultados sugerem a ação de fatores inibidores, tanto humorais como celulares, sobre a resposta imune celular específica ao S. mansoni.

Cell mediated immune response was studied in patients with recent and chronic Schistosoma mansoni infection. Precultured peripheral mononuclear cells showed significantly higher responses to S. mansoni adult worm antigen (SAWA) when compared to fresh cell preparations. The addition of each patient serum to the precultured cells reactions to SAWA or recall antigens demonstrated a strong inhibitory serum action, which was also noted on allogeneic cells derived from healthy subjects. The CD4 subset was the main responding cell to SAWA being this reactivity highly suppressed by the presence of the monocyte macrophage accessory cells. We stressed the simultaneous inhibitory action of humoral and cellular factors on the specific cell response to S. mansoni.