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- Author or Editor: L. Santos x
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Abstract
Nowadays the growing fuel deficit requires the development of alternative fuel sources. Biodiesel is a good substitute to the conventional diesel because it is quite similar to the fossil fuel in its main characteristics. However, there are some obstacles, as the properties of cold-flow, to the development of a more useful alternative fuel. In this work we use the X-ray diffraction and differential calorimetry scanning to study low temperature properties of ethylic Babassu biodiesel. Our results show that the nucleation of crystals starts below −8 °C and the crystallization temperature does not change significantly when the sample was submitted to a winterization process. The higher concentrations of ethyl esters from saturated fat acid are probably responsible for this characteristic. The X-ray diffraction, combined with DSC measurements, was efficiently employed in the characterization of cold-flow biodiesel properties, showing to be very helpful techniques.
Abstract
The conventional treatments of effluents containing heavy metals produce significant quantities of byproducts with recalcitrant characteristics, making necessary looking after alternative techniques in order to avoid the production of new contaminated residues. Sorption process of chromium and zinc in vertical columns loaded with sewage sludge and organic solid waste has been studied in this work. The data from the TG curves of the two sorbents presented significant differences when they were submitted to the metal uptake, being noticed the displacement of the thermal events towards lower temperatures for both types of sorbents studied. As it was expected, for both sorbents, an increase in the mass of samples has been observed at the completion of the thermal tests upon metal uptake. Therefore, these facts demonstrate that during the biosorption process a physico-chemical interaction took place between sorbents and metals, as it was evidenced by the more than 100 K increase in the decomposition temperatures as well as the variation of the ΔH values of the samples.
Summary
Studies performed by the Brazilian Nuclear Corporation (NUCLEBRAS), in collaboration with the Geological Survey Company of Brazil (CPRM), identified high levels of natural uranium in the districts of Pedra and Venturosa, in the rural region of the state of Pernambuco (PE) - Brazil, where the maximum value found in rocks was 22,000 mg.
Abstract
IAEA reference materials (radionuclides in the marine environment) collected in areas affected by nuclear reprocessing plants and nuclear weapons tests have been analysed by semiconductor alpha-spectrometry (SAS), liquid scintillation spectrometry (LSS) and mass spectrometric techniques (high resolution ICP-MS and AMS) with the aim of developing analytical procedures and to study the geochemical behavior of plutonium in the marine environment. The Pu results obtained by SAS, ICP-MS and AMS were in reasonably good agreement (R 2 = 0.99). The mean atom ratios of 240Pu/239Pu in IAEA reference materials, IAEA-134, 135 and 381 were (0.212±0.010), (0.211±0.004) and (0.242±0.004), respectively. IAEA-384 (Fangataufa Lagoon Sediment) gave a 240Pu/239Pu mean atom ratio of 0.051±0.001. The results of 241Pu obtained by ICP-MS and LSS also show reasonable agreement (R 2 = 0.91). Pu isotopic signatures were useful in tracing Pu origin and in interpreting biogeochemical processes involving Pu in the marine environment.
The objective of this study was to evaluate the acceptance of fermented anchovy (Engraulis anchoita) by consumers aged 18–67 (n=100) from two experiments, first using preference test and then by acceptance of formulation preference. Anchovy fillets were fermented with added NaCl and glucose with 4 different treatments: A (NaCl 1% and glucose 4%), B (NaCl 1% and glucose 6%), C (NaCl 1.5% and glucose 4%), and D (NaCl 1.5% and glucose 6% glucose). At first, the preference of fermented anchovy fillets with samples prepared in the form of pizza was assessed by applying a preference ranking test to 75 consumers. The results indicated the sample with 1% NaCl and 6% glucose as the preferred (P>0.05). Later in the second stage, the preferred fermented fillet was subjected to acceptance by 100 consumers who have the consumption habit of such product by using a hedonic scale of 9 points. The results indicated an acceptance rate of 79.8%. This work aimed to call attention to the importance of the acceptance of this food.
Abstract
The most feasible alternative among fuels derived from biomass seems to be the biodiesel, having the required characteristics for a total or partial substitution of diesel oil. Therefore, the aim of this work is to evaluate the thermal and rheological behavior of the blends of diesel with the methanol biodiesel obtained from soybean oil, using B5, B15 and B25 blends. All thermogravimetric curves exhibited one overlapping mass loss step in the 35–280C temperature range at air atmosphere and one step between 37–265C in nitrogen. The rheological study showed a Newtonian behavior (n=1) for all blends.
Abstract
The present work investigates the influence of milling and calcination atmosphere on the thermal decomposition of SrTiO3 powder precursors. Both pure and neodymium-modified SrTiO3 samples were studied. Milling did not significantly influence numerical mass loss value, but reduced the number of decomposition steps, modifying the profiles of the TG and DTA curves. On the other hand, milling increases the amount of energy liberated by the system upon combustion of organic matter. It was also observed that the milling process, associated to the calcination in an oxygen atmosphere, considerably decreases the amount of organic matter and increases the final mass loss temperature.
Abstract
The kinetic and thermodynamic study of synthetic lubricant oils was accomplished in this work, using isothermal and non-isothermal thermogravimetry based on mass loss as a function of time and temperature. The thermodynamic and kinetic behavior of the synthetic lubricant oils depends on atmosphere and heating rates used in TG analysis. The kinetic and thermodynamic results were satisfactory, presenting good correlation.
Forest conversion to anthropogenic uses is a generalized phenomenon throughout tropical Latin America. We evaluated whether patches of secondary forest, which develop relatively rapidly after field abandonment, contribute to conservation of phyllostomid bat assemblages. Our objective was to compare patterns of phyllostomid bat abundance and the structure and composition of phyllostomid bat assemblages across three forest types in the northern neotropics of eastern Mexico. We studied phyllostomid bats within secondary evergreen, primary semi-deciduous, and primary evergreen forests. For each forest type, three representative sites were sampled with mist nets once during the dry season and once during the rainy season for a total of nine sites. Richness, diversity, and assemblage composition patterns were compared among forest types for all phyllostomid species, and for three groups of sensitivity to habitat fragmentation. Abundance of individual species was also compared among forest types. A total of 646 individual bats from 15 species, 11 of which were phyllostomids, were registered. Combining both seasons, more than 250 captures were accomplished at both the primary evergreen and secondary evergreen forests, and only 81 individuals were caught at primary semi-deciduous forests. Overall richness and diversity of species and sensitivity groups were greater in the rainy than the dry season. Richness was greater in secondary evergreen than in primary semi-deciduous forests, and diversity was greatest in the primary evergreen, intermediate in the secondary evergreen, and lowest in the primary semi-deciduous forest. Some overlap in composition was also evident, although there was separation between forest types and seasons. Mean abundances were higher for some species at primary evergreen and secondary evergreen forests, but were threefold lower (though not significantly) in secondary evergreen forests in the dry season for some other species. We also found that primary evergreen forests have the greatest importance for phyllostomids during the dry season. These results suggest that maintenance of secondary evergreen forests, which cover a large proportion of the northeastern Mexican neotropics, would contribute to the conservation of diverse tropical bat communities. Therefore, large areas of this forest type should necessarily be incorporated in the landscape.
Abstract
Poly(3-hydroxybutyrate), PHB, has been structurally modified with maleic anhydride, MA, in the presence of triethylamine, TEA. Glass transition, melting, and crystallization temperature, obtained from DSC curves, and thermal degradation temperatures obtained from TG ones, were employed to evaluate the influence of the MA proportion on the modification in the PHB chain. According to the results, most of chain modification reactions are the 80/20 and 90/10 proportions. Observations suggest that most chain modification reactions occur when the ratio of PHB/MA is 80/20 or 90/10. This suggests that modifications of PHB in the presence of MA involve main chain scission.
