Efeito da temperatura sobre a autoindução magnética do níquel e da platina e a permeabilidade magnética do níquel, no intervalo de temperatura de 525K a 620K, confirma dados encontrados na literatura.

Effect of temperature on the magnetic permeability and magnetic self induction of Nickel and Platinum in the range 525K-620K.

By macroscopic and microscopic dorsal side observation, it was noted that the IX and X segments of two species each of Panstrongylus and Triatoma terminate in an elongated way, whereas they terminate abruptly in the two species of Rhodnius. Scanning observation of the dorsal, ventral, lateral and posterior sides of the female genitalia of Panstrongylus herreri, Panstrongylus megistus, Rhodnius colombiensis, Rhodnius prolixus, Triatoma infestans and Triatoma vitticeps revealed that these six species are generally and specifically distinguished based on these elements. We describe several components that distinguish P. herreri from P. megistus: four on the dorsal side: the VII, VIII, IX and X segments, on the ventral view, three: VII sternite, VIII gonocoxite and VIII gonapophyse, on the lateral view one character, VIII gonocoxite and on the posterior view three characters: VIII and IX gonocoxite and XI gonopophyse. Comparing R. colombiensis and R. prolixus, there were three distinct characters on the dorsal side: the VII, VIII and X segments, on the ventral view three characters: the IX and X segments and VIII gonocoxite and on the posterior view four characters: the VIII, IX, X segments and VIII gonapophyse that distinguish the two species. T. infestans and T. vitticeps have four different characters on the dorsal side: the VII, VIII, IX and X segments, on the ventral view four characters: the VII and X segments, VIII gonocoxite and VIII gonapophyse, on the lateral view two characters, IX and X segments and on the posterior view four characters: the IX and X segments, VIII gonocoxite and VIII gonapophyse that distinguish the two species. Examination of the external female genitalia of six triatomine species by scanning suggests that these components are useful for taxonomical studies.

Porous nano and micro crystalline tin oxide films were deposited by RF Magnetron Sputtering and doctor blade techniques, respectively. Electrical resistance and impedance spectroscopy measurements, as a function of temperature and atmosphere, were performed in order to determine the influence of the microstructure and working conditions over the electrical response of the sensors. The conductivity of all samples increases with the temperature and decreases in oxygen, as expected for an n-type semiconducting material. The impedance plots indicated the existence of two time constants related to the grains and the grain boundaries. The Nyquist diagrams at low frequencies revealed the changes that took place in the grain boundary region, with the contribution of the grains being indicated by the formation of a second semicircle at high frequencies. The better sensing performance of the doctor bladed samples can be explained by their lower initial resistance values, bigger grain sizes and higher porosity.

The present paper aims to verify the inuence of rare earth oxide such as lanthanum (La2O3) and neodymium (Nd2O3) doping SnO2 + 0.25%CoO + 0.75%MnO2 + 0.05%Ta2O5 system. The analysis focus on microstructural inuence on electrical properties. Microstructural analysis were made by using Transmission Electron Microscopy (TEM) at different regions of the samples. From such analysis it was found that La2O3 and Nd2O3 oxides cause heterogeneous segregation and precipitation at grain boundary concerning cobalt and manganese, decreasing the nonohmic electrical properties, as discussed, likely due to the increasing of grain boundary non-active potential barriers.

Foi feito estudo morfológico da face dorsal, ventral e lateral do tórax de ninfas de 1º, 2º, 3º, 4º e 5º estádios de Triatoma arthurneivai por meio de microscopia eletrônica de varredura. Os cinco estádios ninfais podem ser reconhecidos pelos caracteres morfológicos observados no pronoto, mesonoto e metanoto. No 1º estádio nota-se ausência do colar, áreas glabras e tubérculos, que estão presentes no 2º estádio. No 3º estádio inicia-se a diferenciação das aletas alares. No 4º estádio ocorre expansão das quatro aletas alares, que, no entanto, não alcançam o abdome. No 5º estádio as aletas alares anteriores praticamente recobrem as posteriores. Na face ventral dos cinco estádios ninfais percebe-se duas (1+1) aberturas das glândulas metasternais. As áreas de evaporação das glândulas de Brindley localizam-se na mesopleura. Também foram observadas duas (1+1) áreas de evaporação na propleura dos cinco estádios ninfais.

Scanning electron microscope (SEM) was done in order to study dorsal, ventral and lateral sides of 1st, 2nd, 3rd, 4th and 5th nymphal instars of Triatoma arthurneivai. The five nymphal instar can be recognized based on different pronotum, mesonotum and metanotum shapes and characteristics. In the 1st instar collar, hairless areas and tubercles are absent. The 2 nd instar presents collar, hairless areas and tubercles. In the 3rd instar occurs the development of wing pads. In the 4 th instar the four wing pads are expanded, but do not reach the abdomen and in the 5th instar the anterior wing pads almost overlap the posterior ones. At the ventral side, two metasternal glands openings (1+1) were found in all five nymphal instars. Brindley's gland evaporation areas (1+1) are located at the mesopleuron, as well as an evaporation area is located at the propleuron in all nymphal instars (1+1).

This paper reports a study of the influence of Cr concentration and preparation method in the electrical conductivity and microstructure of SnO2-based powders doped with Mn and Nb, prepared by an organic route (Pechini method) and a mixture of oxides. All the samples were compacted into discs and sintered at 1300 °C for 3h, resulting in ceramics with relative density varying between 81 and 99%. The powders were morphologically characterized by X-ray diffraction and their specific surface area was determined by N2 adsorption/desorption isotherms. Electrical conductivity characterization indicated that the conductivity decreases as Cr concentration increases, probably due to Cr segregation at grain boundaries, which reduces grain size, increasing the number of resistive boundaries, thus limiting the passage of current.

Thin films of BBT were deposited on silicate and Pt/Ti /SiO2 (111) substrates by spin- coating from the polymeric precursor method (Pechini process). The obtained films were characterized by optical microscopy, X-ray diffraction and atomic force microscopy. The influence of viscosity on the morphology of BBT thin films as well as the influence of temperature on crystallization, morphology and properties of BBTare discussed. Surface roughness and crystallization of these films are strongly dependent on the annealing conditions.

A entalpia livre de ligação vacância-Mg, em ligas com solução sólida de Al-Cr contendo adição de Mg, foi calculada por medidas de resisitivadade elétrica. O valor obtido foi menor do que aquele obtido para ligas diluídas de Al-Mg com aproximadamente a mesma concentração de Mg e pode ser atribuído à difusão do Mg.

The Mg-vacancy binding free enthalpy of Al-Cr solid solution alloys with Mg addition was calculated by electrical resistivity measurements. The obtained value is lower than that obtained for dilute Al-Mg alloys with almost the same Mg content and may be attributed to the diffusion of Mg.

OBJETIVO: Estudar morfologicamente ovos de T. circummaculata e T. rubrovaria. MÉTODOS: Quarenta ovos das duas espécies foram mensurados por meio de projetor de perfil Nikon modelo 6C, e utilizado o teste Student, para execução da análise estatística. As observações morfológicas foram feitas em microscópio eletrônico de varredura JEOL, modelo JSM-T330A. RESULTADOS/CONCLUSÕES: A análise estatística revelou que os ovos e as cascas de ovos de T. rubrovaria são significativamente maiores que os de T. circummaculata. Observações microscópicas mostraram que a borda corial, assim como a goteira espermática, são bem mais evidentes nos ovos de T. rubrovaria que nos de T. circummaculata. O exocório das duas espécies é formado por áreas poligonais, que são hexagonais em sua maioria. Foram observados também o momento da eclosão do embrião e os detalhes das exúvias embrionárias.

OBJECTIVE: To study morphologically the eggs of T. circummaculata and T. rubrovaria. METHODS: Forty eggs of the two species were measured through Nikon model 6C profile projector. Student test was utilized for the statistical analysis and scanning electron microscopy for the morphological study of the eggs. RESULTS/CONCLUSIONS: The statistical analysis shows that the T. rubrovaria eggs are larger that those of T. circummaculata. Microscopical observations revealed that the chorial rim and the spermatic groove are less evident in T. circummaculata than in T. rubrovaria. Both species, the majority of exochorion cells are hexagonal. It was also observed the embryo eclosion and details of the embryonic molt.

OBJETIVO: Estudar morfologicamente ovos de T. circummaculata e T. rubrovaria. MÉTODOS: Quarenta ovos das duas espécies foram mensurados por meio de projetor de perfil Nikon modelo 6C, e utilizado o teste Student, para execução da análise estatística. As observações morfológicas foram feitas em microscópio eletrônico de varredura JEOL, modelo JSM-T330A. RESULTADOS/CONCLUSÕES: A análise estatística revelou que os ovos e as cascas de ovos de T. rubrovaria são significativamente maiores que os de T. circummaculata. Observações microscópicas mostraram que a borda corial, assim como a goteira espermática, são bem mais evidentes nos ovos de T. rubrovaria que nos de T. circummaculata. O exocório das duas espécies é formado por áreas poligonais, que são hexagonais em sua maioria. Foram observados também o momento da eclosão do embrião e os detalhes das exúvias embrionárias.

OBJECTIVE: To study morphologically the eggs of T. circummaculata and T. rubrovaria. METHODS: Forty eggs of the two species were measured through Nikon model 6C profile projector. Student test was utilized for the statistical analysis and scanning electron microscopy for the morphological study of the eggs. RESULTS/CONCLUSIONS: The statistical analysis shows that the T. rubrovaria eggs are larger that those of T. circummaculata. Microscopical observations revealed that the chorial rim and the spermatic groove are less evident in T. circummaculata than in T. rubrovaria. Both species, the majority of exochorion cells are hexagonal. It was also observed the embryo eclosion and details of the embryonic molt.

A influência de adições de 2, 4, 6 e 8% de prata, em peso, na cinética de recristalização da liga Cu-5%Al com taxas de deformação de 40, 70 e 90%, foi estudada utilizando-se metalografia por microscopia óptica e medidas de variação do tamanho de grão com o tempo e a temperatura de envelhecimento. Os resultados obtidos indicaram uma diminuição na velocidade de crescimento dos grãos e na energia de ativação correspondente, com o aumento da concentração de prata.

The influence of additions of 2, 4, 6 and 8 wt.% Ag on the recrystallization kinetics of the Cu-5wt.%Al alloy cold-rolled to reductions up to 40, 70 and 90% was studied using the intercept method for measurements of mean grain size changes with time and temperature. The results indicated a decrease in the grain growth rate and in the activation energy with the increase of silver concentration.

Estudou-se a influência de adições de 2, 6 e 8% Ag, em peso, na resistividade elétrica da liga Cu-5%Al, utilizando-se o método dos quatro pontos e um sistema de registro contínuo de variação da resistividade elétrica com a temperatura. Os resultados obtidos indicaram que a resistividade elétrica da liga aumenta com o aumento da concentração de prata e que as inflexões observadas nas curvas de variação da resistividade com a temperatura de aquecimento podem ser atribuídas à solubilização da prata na matriz de Cu-Al. Observou-se também que a velocidade de aquecimento da amostra é um fator importante na intensidade e forma dos eventos observados.

The influence of additions fo 2, 6, and 8 wt. % Ag on the electrical resistivity of the Cu-5 wt. %Al alloy was studied by the four-probe d.c. method and an automated recorder system. The results indicated that the electrical resistivity of the alloy increases with silver concentration and that the inflexions on the curves of electrical resistivity changes with temperature may be ascribed to silver solubilization on the Cu-Al matrix. It was also observed that the sample heating rate may change the shape of the curve recorded.

As temperaturas onde ocorre a solubilização da fase rica em prata, em ligas de Cu-Al-Ag, foram determinadas através de medidas de variação da resistência elétrica com a temperatura. As derivadas das curvas obtidas experimentalmente permitiram determinar com precisão essas temperaturas e também que se traçasse um esboço da região onde ocorre a transição monofásica para bifásica.

The silver-rich phase solubilization temperatures in Cu-Al-Ag alloys were obtained by electrical resistance measurements. The derivative of the experimental curves allowed the precise determination of these temperatures and also the sketch of the one phase-two phases transition region.