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Search Results: 1 - 10 of 37711 matches for " António André Chivanga Barros "
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Heterogeneous catalysts for use in the production of Biodiesel
Kamila Colombo,António André Chivanga Barros
Evidência : Ciência e Biotecnologia - Interdisciplinar , 2009,
Abstract: The search for cleaner fuels has resulted in the development of research for the processing of fats and oils, composed mainly of fatty acids with high energy and capable of conversion into esters (biodiesel) by transesterification or esterification reactions inhomogeneous catalysis, heterogeneous enzymatic or supercritical. The homogeneous transesterification is the most widely used, however the products obtained concentrated high levels of impurities, why are complemented secondary purification procedures such as liquid-liquid extraction and simple distillation, processes that enhance the generation of waste. The problems identified with the use of transesterification with homogeneous catalysis can be minimized by transesterification with heterogeneous catalysis that seeks to improve the effectiveness of biodiesel production. Thus, studies were conducted with heterogeneous catalysis transesterificationin a laboratory scale reactor, jacketed, with agitation system, temperature controlled and sealed to prevent the diffusion ofreagents to the environment. The heterogeneous catalyst used in these studies was developed by dissolution of potassium hydroxidein water and subsequent impregnation of aqueous solution, formed in clay and subsequent calcination. Thecatalyst was integrated in the reactor and added the necessary reagents for the production of biodiesel. Throughout the execution ofexperiments, controlling the process parameters such as reaction time, temperature and degree of agitation. The products obtainedwere evaluated and calculated the degree of conversion of fat into fatty acid esters and final concentration of esters.
Absor??o química de dióxido de nitrogênio (NO2)
Leite, André Búrigo;Bertoli, Sávio Leandro;Barros, António André Chivanga;
Engenharia Sanitaria e Ambiental , 2005, DOI: 10.1590/S1413-41522005000100006
Abstract: the gaseous absorption is commonly used in the industry of processes for the recovery/obtain compounds with a high aggregated value, as well as for the minimization of pollutants in aerial contaminated environments. in this work, the influence of the parameters of the processes was evaluated for recovery of the no2, using the commercial simulator process provision (pro ii ?). with the results obtained, a relation between the absorption rates, with chemical reaction, and the capacity of mass transference along the absorption column with plates, was established. the hno3 can be recouped, being able to come to be substance manufacture.
Estudo da viabilidade técnico-científica da produ??o de biodiesel a partir de resíduos gordurosos
Barros, António André Chivanga;Wust, Elisiane;Meier, Henry Fran?a;
Engenharia Sanitaria e Ambiental , 2008, DOI: 10.1590/S1413-41522008000300003
Abstract: waste fatty acid, from fatty boxes was evaluated as feedstock to obtain biodiesel in a laboratory scale. the residues were desemulsified, purified and used to obtain ethyl esters, through the transesterification with alkaline catalysis and esterification with acid catalysis reactions. the product was purified by adsorption in column of silica, and characterized by glc with mass detector. using this methodology the fatty residues was converted in the ethyl esters showed the scientific e technical validation of this propose. the conversion of fatty acids in ethylic esters was calculated by mass balances processes same for the highs degradation of the residue evaluates. to purify the biodiesel and glycerol obtained was necessary secondary processes to increase the qualities of this full and to use the glycerin in many industrial processes.
Craqueamento termo-catalítico da mistura óleo de fritura usado-lodo de estamparia têxtil para a produ??o de óleo com baixo índice de acidez
Botton, Vanderléia;Riva, Dilamara;Simionatto, Edesio Luiz;Wiggers, Vinicyus Rodolfo;Ender, Laércio;Meier, Henry Fran?a;Barros, António André Chivanga;
Química Nova , 2012, DOI: 10.1590/S0100-40422012000400004
Abstract: in this work, cracking experiments were performed to carry out the thermal conversion of the mixture of used frying oil and textile stamping sludge in continuous reactor. the textile stamping sludge was used to catalyze the reaction of thermal cracking. the physical and chemical properties of the oil produced were analyzed. among the results of this analysis the level of acidity in the range of 12 mg koh/g stands out. low levels of acidity as this particular mean better quality oil. in this regard it is important that further researches on processes of conversion of residual oil occur.
Alergia látex-fruta
MARIN, Flávia Andréia;PERES, Suely Prieto de Barros Almeida;ZULIANI, Antnio;
Revista de Nutri??o , 2002, DOI: 10.1590/S1415-52732002000100010
Abstract: the latex is being considered the allergenic agent of the year 2000, taking into account that several individuals, mainly health care professionals, and patients who had undergone many diagnostic and therapeutic interventions, are frequently exposed to latex allergens, which are present in natural rubber latex products. the clinical manifestations, derived from allergic reactions of immediate hypersensitivity vary from since rhinitis, conjunctivitis, urticaria, angioedema, asthma, to anaphylaxis. recent researches are demonstrating that patients allergic to latex develop concomitantly sensitization to certain vegetable foods, especially fruits like papaya, fig, banana, avocado, kiwi, peach, pineapple, melon and chestnut, and a probable occurrence of cross reaction between allergens of latex and of these fruits is believed. a review is made about latex allergy, in particular about risk groups, including the presence of cross-reactivity between latex and fruit.
Alergia látex-fruta
MARIN Flávia Andréia,PERES Suely Prieto de Barros Almeida,ZULIANI Antnio
Revista de Nutri??o , 2002,
Abstract: O látex está sendo considerado o alergênico do ano 2000, tendo em vista que inúmeros indivíduos, principalmente profissionais da área de saúde e pacientes submetidos a várias interven es diagnósticas e terapêuticas, est o freqüentemente expostos aos alérgenos do látex, presentes em produtos de borracha natural. As manifesta es clínicas conseqüentes às rea es alérgicas de hipersensibilidade imediata v o desde rinite, urticária, conjuntivite, angioedema, asma, até anafilaxia. Estudos recentes est o demonstrando que pacientes alérgicos ao látex desenvolvem concomitantemente sensibiliza o a certos alimentos de origem vegetal, especialmente frutas como papaia, figo, banana, abacate, kiwi, pêssego, abacaxi, mel o e castanha, acreditando-se numa provável ocorrência de rea es cruzadas entre os alérgenos do látex e destas frutas. Faz-se, ent o, uma revis o sobre a alergia ao látex, em particular sobre os grupos de risco, incluindo a presen a de reatividade cruzada entre o látex e as frutas.
Influência da temperatura de austenitiza??o sobre a cinética de forma??o da ferrita em um a?o microligado com Nb
Cota, André Barros;Lacerda, Cássio Antnio Mendes;Oliveira, Fernando Lucas Gon?alves e;Araújo, Fernando Gabriel Silva;
Rem: Revista Escola de Minas , 2002, DOI: 10.1590/S0370-44672002000400008
Abstract: the effect of austenitization temperature on austenite transformation for a low-carbon steel and microalloyed with nb was investigated under continuous cooling conditions by means of differential thermal analysis. the starting temperature for ferrite formation depends strongly on austenitization temperature due to its effect on the austenite grain size. increase in austenitization temperature implies increase in austenite grain size and decrease in temperature starts ferrite formation. the presence of nb in solution during the transformation increases the transformation time of austenite to ferrite and reduces its effective transformation rate, leading to the formation of granular bainite, at the austenitization temperature of 1100oc and air cooling.
Doen?a inflamatória intestinal - Doen?a de Crohn e gravidez: relato de caso
Braga, Antnio;Antunes, Samantha;Marcolino, Luciano;Moraes, Valéria;Duarte, Luciana de Barros;Accetta, André;Leal, Rosilene Alves Teixeira;
Revista Brasileira de Ginecologia e Obstetrícia , 2011, DOI: 10.1590/S0100-72032011000400008
Abstract: the crohn's disease, a form of inflammatory bowel disease, is frequent in women of childbearing age. its management requires greater attention during pregnancy. we report a case of refractory crohn's disease in a pregnant patient that evolued to ileocolectomy at puerperium. the literature regarding pregnant patients with crohn's disease was reviewed, including counseling of patients and investigation of active disease, and the existing data was summarized on the safety of medications used to treat crohn's disease in pregnancy and breastfeeding.
Influência da temperatura de austenitiza o sobre a cinética de forma o da ferrita em um a o microligado com Nb
Cota André Barros,Lacerda Cássio Antnio Mendes,Oliveira Fernando Lucas Gon?alves e,Araújo Fernando Gabriel Silva
Rem: Revista Escola de Minas , 2002,
Abstract: O efeito da temperatura de austenitiza o sobre a cinética de transforma o da austenita em um a o microligado com Nb foi estudado em resfriamento contínuo através da análise térmica diferencial. Verifica-se uma forte dependência da temperatura de início de forma o da ferrita alotriomórfica com a temperatura de austenitiza o devido ao seu efeito sobre o tamanho de gr o austenítico. O aumento da temperatura de austenitiza o implica um aumento no tamanho de gr o austenítico e uma diminui o na temperatura de início de transforma o da austenita em ferrita. A presen a de Nb em solu o durante a transforma o aumenta o tempo de transforma o da austenita em ferrita alotriomórfica, reduz a taxa efetiva de transforma o, levando à forma o de bainita granular para temperatura de austenitiza o de 1100masculineC e resfriamento no ar.
Effect of processing parameters on scale formation during hot steel strip rolling
Lima Júnior, Sergio de Oliveira;Bellon, Júlio Cezar;Souza Júnior, Paulo Antnio de;Araújo, Fernando Gabriel da Silva;Cota, André Barros;
Materials Research , 2010, DOI: 10.1590/S1516-14392010000100004
Abstract: the influence of processing parameters (slab thickness, water flow of interstand cooling and oil flow in roll gap lubrication system) on the thickness and composition of the tertiary scale formed during hot strip rolling, was studied in a low carbon steel in factory. the scale formed on the rolled surface was characterized by scanning electron microscopy and m?ssbauer spectroscopy. it was observed that the combined effect of a greater rolling oil volume applied, larger bar thickness, and smaller amount of water flow during interstand cooling reduces the tertiary scale thickness. besides, a smaller crack density in the samples is associated with greater rolling oil volume and smaller oxide scale thickness. the principal phase of the scale formed in hot-rolled steel strips is stoichiometric magnetite, without isomorphic substitutions.
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