991 resultados para Brito, Antonio Carlos de, 1944-1987


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The purpose of this study was to evaluate the accuracy of hand-held refractometer in determining serum protein concentrations in ring-necked pheasants (Phasianus colchicus) as compared with the standard biuret method. The results indicated that serum protein values may be accurately determined in ring-necked pheasants with a hand-held refractometer. © Asian Network for Scientific Information, 2008.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Laboratory tests to detect urinary infection at a lawer cost than uroculture are necessary. Triphenyl tetrazolium chloride was evaluated in parallel with uroculture in 342 urine samples, for the detection of significant bacteriuria. The results showed that the test has high sensitivity (91.3%) but low specificity (64.3%), and negative predictive value 99.0%. Although the test cannot replace uroculture as a diagnostic method, it can be recommended for preliminary screening, and could eliminate the need for uroculture of negative samples.

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Baccharis coridifolia is one of the most important poisonous plants to cattle in the South of Brazil. The plant provokes necrotic lesions in the lymphoid tissues and in the gastrointestinal tract of cattle. Experimental administration to mice produces most of the lesions seen in the lymphoid tissues of cattle. This study was conducted to search possible differences in the susceptibility of T and B lymphocyte subpopulations. Lymph nodes, spleen, thymus and gut-associated lymphoid tissue (GALT) of cattle and mice experimentally poisoned were evaluated. The results were evaluated based on cell populations affected or remaining in the organs. Immunostaining for B lymphocytes (anti-BLA-36) identified the germinal center of follicles of the lymph node, spleen and GALT in both species. Immunostaining for T lymphocyte (anti-CD3) identified the paracortical area of the germinal centers of the lymph nodes and GALT, the periarteriolar area of the spleen, and the whole thymus both in cattle and mice. Experimentally poisoned cattle and mice shows necrosis of the germinal center of secondary follicles of the lymph nodes, spleen and GALT, where necrotic cells were immunostained for B and less often for T lymphocyte. Necrotic cells in the paracortical region of the lymph node were less often and were immunostained. Necrotic lesions of the thymus were seen only in mice, with positively stained for T lymphocyte. The distribution of the lesions in the lymphoid tissues and the immunostaining in necrotic cells suggested that the active principles of the plant are cytotoxic to B and T cells.

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An expressive amount of produced hydrogen is generated by customers in-situ such as petrochemical, fertilizer and sugarcane industries. However, the most utilized feedstock is natural gas, a non-renewable and fossil fuel. The introduction of biohydrogen production process associated in a sugarcane industry is an alternative to diminish emissions and contribute to create a CO2 cycle, where the plants capture this gas by photosynthesis process and produces sucrose for ethanol production. The cost of production of ethanol has dramatically decreased (from about US$ 700/m3 in 1970s to US$ 200/m3 today), becoming this a good option at near term, inclusively for its utilization by customers localized in main regions (localized especially in regions such as Southeastern Brazil) Also in near future, it will possible the utilization of fuel cells as form of distributed generation. Its utilization could occur specially in peak hours, diminishing the cost of investments in newer transmission systems. A technical and economic analysis of steam reformer of ethanol to hydrogen production associated with sugarcane industry was recently performed. This technique will also allow the use of ethanol when its price is relatively low. This study was based on a previous R&D study (sponsored by CEMIG - State of Minas Gerais Electricity Company) where thermodynamic and economic analyses were developed, based in the development of two ethanol steam reformers prototypes.x In this study an analysis was performed considering the use of bagasse as source of heat in the steam reforming process. Its use could to diminish the costs of hydrogen production, especially at large scale, obtaining cost-competitive production and permitting that sugarcane industry produces hydrogen in large scale beyond ethylic alcohol, anhydrous alcohol (or ethanol) and sugar.

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This work has as objective to demonstrate technical and economic viability of hydrogen production utilizing glycerol. The volume of this substance, which was initially produced by synthetic ways (from oil-derived products), has increased dramatically due mainly to biodiesel production through transesterification process which has glycerol as main residue. The surplus amount of glycerol has been generally utilized to feed poultry or as fuel in boilers, beyond other applications such as production of soaps, chemical products for food industry, explosives, and others. The difficulty to allocate this additional amount of glycerol has become it in an enormous environment problem, in contrary to the objective of biodiesel chain, which is to diminish environmental impact substituting oil and its derivatives, which release more emissions than biofuels, do not contribute to CO2-cycle and are not renewable sources. Beyond to utilize glycerol in combustion processes, this material could be utilized for hydrogen production. However, a small quantity of works (theoretical and experimental) and reports concerning this theme could be encountered. Firstly, the produced glycerol must be purified since non-reacted amounts of materials, inclusively catalysts, contribute to deactivate catalysts utilized in hydrogen production processes. The volume of non-reacted reactants and non-utilized catalysts during transesterification process could be reutilized. Various technologies of thermochemical generation of hydrogen that utilizes glycerol (and other fuels) were evaluated and the greatest performances and their conditions are encountered as soon as the most efficient technology of hydrogen production. Firstly, a physicochemical analysis must be performed. This step has as objective to evaluate the necessary amount of reactants to produce a determined volume of hydrogen and determine thermodynamic conditions (such as temperature and pressure) where the major performances of hydrogen production could be encountered. The calculations are based on the process where advance degrees are found and hence, fractions of products (especially hydrogen, however, CO2, CO, CH4 and solid carbon could be also encountered) are calculated. To produce 1 Nm3/h of gaseous hydrogen (necessary for a PEMFC - Proton Exchange Membrane Fuel Cell - containing an electric efficiency of about 40%, to generate 1 kWh), 0,558 kg/h of glycerol is necessary in global steam reforming, 0,978 kg/h of glycerol in partial oxidation and cracking processes, and 0,782 kg/h of glycerol in autothermal reforming process. The dry reforming process could not be performed to produce hydrogen utilizing glycerol, in contrary to the utilization of methane, ethanol, and other hydrocarbons. In this study, steam reforming process was preferred due mainly to higher efficiencies of production and the need of minor amount of glycerol as cited above. In the global steam reforming of glycerine, for one mole of glycerol, three moles of water are necessary to produce three moles of CO2 and seven moles of H2. The response reactions process was utilized to predict steam reforming process more accurately. In this mean, the production of solid carbon, CO, and CH4, beyond CO2 and hydrogen was predicted. However, traces of acetaldehyde (C2H2), ethylene (C2H4), ethylene glycol, acetone, and others were encountered in some experimental studies. The rates of determined products obviously depend on the adopted catalysts (and its physical and chemical properties) and thermodynamic conditions of hydrogen production. Eight reactions of steam reforming and cracking were predicted considering only the determined products. In the case of steam reforming at 600°C, the advance degree of this reactor could attain its maximum value, i.e., overall volume of reactants could be obtained whether this reaction is maintained at 1 atm. As soon as temperature of this reaction increases the advance degree also increase, in contrary to the pressure, where advance degree decrease as soon as pressure increase. The fact of temperature of reforming is relatively small, lower costs of installation could be attained, especially cheaper thermocouples and smaller amount of thermo insulators and materials for its assembling. Utilizing the response reactions process in steam reforming, the predicted volumes of products, for the production of 1 Nm3/h of H2 and thermodynamic conditions as cited previously, were 0,264 kg/h of CO (13% of molar fraction of reaction products), 0,038 kg/h of CH4 (3% of molar fraction), 0,028 kg/h of C (3% of molar fraction), and 0,623 kg/h of CO2 (20% of molar fraction). Through process of water-gas shift reactions (WGSR) an additional amount of hydrogen could be produced utilizing mainly the volumes of produced CO and CH4. The overall results (steam reforming plus WGSR) could be similar to global steam reforming. An attention must to be taking into account due to the possibility to produce an additional amount of CH4 (through methanation process) and solid carbon (through Boudouard process). The production of solid carbon must to be avoided because this reactant diminishes (filling the pores) and even deactivate active area of catalysts. To avoid solid carbon production, an additional amount of water is suggested. This method could be also utilized to diminish the volume of CO (through WGSR process) since this product is prejudicial for the activity of low temperature fuel cells (such as PEMFC). In some works, more three or even six moles of water are suggested. A net energy balance of studied hydrogen production processes (at 1 atm only) was developed. In this balance, low heat value of reactant and products and utilized energy for the process (heat supply) were cited. In the case of steam reforming utilizing response reactions, global steam reforming, and cracking processes, the maximum net energy was detected at 700°C. Partial oxidation and autothermal reforming obtained negative net energy in all cited temperatures despite to be exothermic reactions. For global steam reforming, the major value was 114 kJ/h. In the case of steam reforming, the highest value of net energy was detected in this temperature (-170 kJ/h). The major values were detected in the cracking process (up to 2586 kJ/h). The exergetic analysis has as objective, associated with physicochemical analysis, to determine conditions where reactions could be performed at higher efficiencies with lower losses. This study was performed through calculations of exergetic and rational efficiencies, and irreversibilities. In this analysis, as in the previously performed physicochemical analysis, conditions such as temperature of 600°C and pressure of 1 atm for global steam reforming process were suggested due to lower irreversibility and higher efficiencies. Subsequently, higher irreversibilities and lower efficiencies were detected in autothermal reforming, partial oxidation and cracking process. Comparing global reaction of steam reforming with more-accurate steam reforming, it was verified that efficiencies were diminished and irreversibilities were increased. These results could be altered with introduction of WGSR process. An economic analysis could be performed to evaluate the cost of generated hydrogen and determine means to diminish the costs. This analysis suggests an annual period of operation between 5000-7000 hours, interest rates of up to 20% per annum (considering Brazilian conditions), and pay-back of up to 20 years. Another considerations must to be take into account such as tariffs of utilized glycerol and electricity (to be utilized as heat source and (or) for own process as pumps, lamps, valves, and other devices), installation (estimated as US$ 15.000 for a plant of 1 Nm3/h) and maintenance cost. The adoption of emission trading schemes such as carbon credits could be performed since this is a process with potential of mitigates environment impact. Not considering credit carbons, the minor cost of calculated H2 was 0,16288 US$/kWh if glycerol is also utilized as heat sources and 0,17677 US$/kWh if electricity is utilized as heat sources. The range of considered tariff of glycerol was 0-0,1 US$/kWh (taking as basis LHV of H2) and the tariff of electricity is US$ 0,0867 US$/kWh, with demand cost of 12,49 US$/kW. The costs of electricity were obtained by Companhia Bandeirante, localized in São Paulo State. The differences among costs of hydrogen production utilizing glycerol and electricity as heat source was in a range between 0,3-5,8%. This technology in this moment is not mature. However, it allows the employment generation with the additional utilization of glycerol, especially with plants associated with biodiesel plants. The produced hydrogen and electricity could be utilized in own process, increasing its final performance.

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The aim of this study was to identify the resistance profile of Staphylococcus aureus strains, in relation to induced clindamycin resistance, and to detect oxacillin resistance by the routine phenotypic methods. The strains were isolated from nasal or lingual swabs taken from healthy adult carriers with no medical history of hospitalization or antibiotic treatment. Eighteen strains were distinguished by the different patterns generated by pulsed field gel electrophoresis (PFGE). Four (22.2%) of these showed sensitivity to clindamycin by the conventional antibacterial susceptibility test, but demonstrated inducible resistance to it by the D-test. One strain (5.6%) was characterized as borderline oxacillin-resistant S. aureus (BORSA), and another (5.6%) as CA MRSA (community-associated methicillin-resistant Staphylococcus aureus). Both of these strains were shown to be cefoxitin susceptible by the disk diffusion test. The polymerase chain reaction (PCR) failed to detect the mecA gene in this last strain and it was thus classified as BORSA. These results show the importance of incorporating the D-test into the routine lab tests for S. aureus inducible clindamycin resistance and also of including the cefoxitin resistance test among the phenotypic methods for MRSA characterization.

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Incluye Bibliografía

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Objective: There is strong evidence that methylene blue (MB), an inhibitor of guanylate cyclase, is an excellent therapeutic option for vasoplegic syndrome (VS) treatment in heart surgery. The aim of this article is to review the MB's therapeutic function in the vasoplegic syndrome treatment. Methods: Fifteen years of literature review. Results: 1) Heparin and ACE inhibitors are risk factors; 2) In the recommended doses it is safe (the lethal dose is 40 mg/ kg); 3) The use of MB does not cause endothelial dysfunction; 4) The MB effect appears in cases of nitric oxide (NO) up-regulation; 5) MB is not a vasoconstrictor, by blocking of the GMPc system it releases the AMPc system, facilitating the norepinephrine vasoconstrictor effect; 6) The most used dosage is 2 mg/kg as IV bolus followed by the same continuous infusion because plasmatic concentrations strongly decays in the first 40 minutes; 7) There is a possible window of opportunity for the MB's effectiveness. Conclusions: Although there are no definitive multicentric studies, the MB used to treat heart surgery VS, at the present time, is the best, safest and cheapest option, being a Brazilian contribution for the heart surgery.