Authors:Rosiane M. C. Farias, Marta M. Conceição, Roberlúcia A. Candeia, Marta C. D. Silva, Valter J. Fernandes Jr., and Antonio G. Souza
The diversity of raw materials and technological routes employed in the biodiesel production has resulted in products with different chemical properties. This non-uniformity in the biodiesel composition may influence to the fuel quality. The aim of this study was to evaluate biodiesel blends of passion fruit and castor oil in different proportions and their thermal stability. Biodiesel blends of passion fruit and castor oil presented parameters in the standards of the Petroleum, Natural Gas and Biofuels National Agency. The TG curves indicated that castor oil biodiesel was more stable. Passion fruit biodiesel has a high content of oleic and linoleic acids, which are more susceptible to oxidation. Biodiesel blend of passion fruit and castor oil 1:1 increased the thermal stability in relation to passion fruit biodiesel. Biodiesel blend of passion fruit and castor oil 1:2 presented higher thermal stability, because castor oil has a high content of ricinoleic acid.
Authors:F. T. G. Vieira, A. L. M. Oliveira, D. S. Melo, S. J. G. Lima, E. Longo, A. S. Maia, A. G. Souza, and I. M. G. Santos
Alkaline earth stannates have recently become important materials in ceramic technology due to its application as humidity sensor. In this work, alkaline earth stannates doped with Fe3+ were synthesized by the polymeric precursor method, with calcination at 300 °C/7 h and between 400 and 1100 °C/4 h. The powder precursors were characterized by TG/DTA after partial elimination of carbon. Characterization after the second calcination step was done by X-ray diffraction, infrared spectroscopy, and UV–vis spectroscopy. Results confirmed the formation of the SrSnO3:Fe with orthorhombic perovskite structure, besides SrCO3 as secondary phase. Crystallization occurred at 600 °C, being much lower than the crystallization temperature of perovskites synthesized by solid state reaction. The analysis of TG curves indicated that the phase crystallization was preceded by two thermal decomposition steps. Carbonate elimination occurred at two different temperatures, around 800 °C and above 1000 °C.
Authors:D. Gouveia, A. Souza, M. de Maurera, C. da Costa, I. Santos, S. Prasad, J. de Lima, C. Paskocimas, and E. Longo
Using the Pechini method, pigments with spinel structure (Zn7Sb2O12)were synthesized by substitution of the cation Zn2+ by Co2+, in compounds with different concentrations of Sb2O3. The doping resulted in CoxZn(7–x)Sb2O12 phases(x=1–7) that were isomorphs to spinel, denominated as samples A and B. After thermal treatment at 400C for 1 h, the powders
were characterized by thermogravimetry(TG) and differential thermal analysis (DTA). The results indicate a different behavior
whena higher amount of Sb2O3 is used, due to the presence of a secondary phase (ilmenite).
Authors:Alexandre G. S. Prado, Sheila M. Evangelista, Jurandir R. SouzaDe, Jeane G. S. Matos, Marco A. A. Souza, Denise A. Oliveira, and Claudio Airoldi
A microcalorimetric method was applied to study microbial soil activity of ornamental flower (Dahlia pinnata) plantations when irrigated with potable water and wastewaters. The samples were irrigated with potable water PW sample (reference) and treated wastewaters from Municipal Wastewater Treatment Station of Asa Norte in Brasilia City (Brazil). Three different water treatments were applied to irrigate soil samples, named TW1, TW2, and TW3 samples. The increase of the microbial soil activity observed in TW1 sample must have occurred because of the high amount of organic waste dissolved in wastewater used for irrigation. This rise indicates that the present treated wastewater can affect natural life cycle. However, only a low alteration in microbial soil activity was observed in the TW2 and TW3 samples, which suggests that these wastewater treatments can be normally used to irrigate soils without bringing environmental consequences, once they offer a great opportunity to upgrade and protect the environment.
Authors:Renato X. Coutinho, Eliziane S. Dávila, Wendel M. dos Santos, João B. T. Rocha, Diogo O. G. Souza, Vanderlei Folmer, and Robson L. Puntel
In the present study we analyzed the Brazilian scientific production in the area of science education. The study was structured on: data by research groups registered in Conselho Nacional de Desenvolvimento Científico e Tecnológico; analysis of the post-graduate strictu sensu programs; analysis of theses and dissertations linked to post-graduate programs; and papers in international databases. Our research was conducted strictly via world wide web, from December 2009 to September 2010. It was found that both number of research groups, researchers, post-graduate programs, thesis, dissertations and papers presented a marked increase, especially in the last decade (from 2000 onwards). The major research centers were found to be located in public universities from Brazilian southeast and south regions. However, it was observed a tendency of decentralization, due to a recent investment in new public universities in the other Brazilian regions. So, this study sought to present an overview of the scientific production about science education and we expect that this information can help to expand the vision about the development of this research area in Brazil.