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Search Results: 1 - 10 of 705453 matches for " Silva G.L.J.P "
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Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation
Silva, G.L.J.P. da;Silva, M.L.C.P. da;Caetano, Tatiana;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000200011
Abstract: this paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. the precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. seven compounds were prepared and characterized by thermal analysis, x-ray diffractometry and by surface area measurements. amorphous forms were obtained in each case, a result that agrees with those obtained by conventional gel precipitation methodology. all these materials present surface area values of >148 m2.g-1, determined after heat treatment at 50 °c. the ion exchange behavior of each hydrous zirconium oxide prepared was studied using k+ as the exchanged species and the results compared with those obtained for hydrous zirconium oxide originally precipitated by the sol gel method.
Evaluation of inorganic matrixes as supports for immobilization of microbial lipase
Castro, H.F.;Silva, M.L.C.P.;Silva, G.L.J.P;
Brazilian Journal of Chemical Engineering , 2000, DOI: 10.1590/S0104-66322000000400048
Abstract: candida rugosa was immobilized by physical adsorption on several inorganic supports using hexane as coupling medium. the enzymatic activities of the different derivatives were determined by both hydrolysis of olive oil and esterification of n-butanol with butyric acid. the results were compared to previous data obtained by using a controlled porous silica matrix. the goal was to contribute in searching inexpensive supports for optimum lipase performance. all supports examined exhibited good properties for binding the enzyme lipase. zirconium phosphate was the best support, giving the highest percentage of protein fixation (86%) and the highest retention of lipase activity after immobilization (34%). the operational stability performance for niobium oxide derivative was improved by previously activated the support with silane and glutaraldehyde. thermal stabilities were also examined by thermal gravimetric analysis (tg).
Preparation and Characterization of Hydrous Zirconium Oxide Formed by Homogeneous Precipitation
Silva G.L.J.P. da,Silva M.L.C.P. da,Caetano Tatiana
Materials Research , 2002,
Abstract: This paper reports on the preparation, characterization and study of the ion exchange behavior of hydrous zirconium oxides formed by homogeneous precipitation from zirconium oxychloride. The precipitants used were obtained by thermal decomposition of urea, sodium nitrite or ammonium carbonate. Seven compounds were prepared and characterized by thermal analysis, X-ray diffractometry and by surface area measurements. Amorphous forms were obtained in each case, a result that agrees with those obtained by conventional gel precipitation methodology. All these materials present surface area values of >148 m2.g-1, determined after heat treatment at 50 °C. The ion exchange behavior of each hydrous zirconium oxide prepared was studied using K+ as the exchanged species and the results compared with those obtained for hydrous zirconium oxide originally precipitated by the sol gel method.
Evaluation of inorganic matrixes as supports for immobilization of microbial lipase
Castro H.F.,Silva M.L.C.P.,Silva G.L.J.P
Brazilian Journal of Chemical Engineering , 2000,
Abstract: Candida rugosa was immobilized by physical adsorption on several inorganic supports using hexane as coupling medium. The enzymatic activities of the different derivatives were determined by both hydrolysis of olive oil and esterification of n-butanol with butyric acid. The results were compared to previous data obtained by using a controlled porous silica matrix. The goal was to contribute in searching inexpensive supports for optimum lipase performance. All supports examined exhibited good properties for binding the enzyme lipase. Zirconium phosphate was the best support, giving the highest percentage of protein fixation (86%) and the highest retention of lipase activity after immobilization (34%). The operational stability performance for niobium oxide derivative was improved by previously activated the support with silane and glutaraldehyde. Thermal stabilities were also examined by thermal gravimetric analysis (TG).
Hydrous Tantalum Phosphates for Ion Exchange Purposes: A Systematic Study
Silva, M.L.C.P.da;Silva, G.L.J.P. da;Villela Filho, D.N.;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000100012
Abstract: this work describes two methods of preparation of hydrous tantalum phosphates and their characterization as ion exchangers. the hydrous metallic phosphate compounds were chemically and physically characterized by thermal gravimetric analysis, x-ray diffractometry and surface area measurements. by the first method, tantalum phosphate was prepared by alkaline fusion of ta2o5 with an excess of k2co3, followed by lixiviation of the tantalate fusion product with hot water, and precipitation with diluted h3po4. preparation ii was performed using metallic ta dissolved in concentrated hf/hno3 acidic mixture followed by hydrolysis of fluortantalic acid intermediary and precipitation with diluted h3po4. both freshly prepared materials (i and ii) were exaustively refluxed with concentrated h3po4, in its boiling point temperature, resulting respectively in ta2o5. 2.1 h2o, (ir) and ta2o5. 1.3 h2o, (iir). characterization of the prepared products have presented the following values: surface area of 108.27 ± 2.80; 220.14 ± 2.67; 117.07 ± 5.25 and 141.61 ± 0.27 m2.g-1 respectively for i, ir, ii and iir. all these materials were amorphous. the ion exchange behavior for all four hydrous tantalum phosphates was studied using na+, k+ and ba+2 as the exchanged species. the values for typical ion exchange capacity were 1.64; 1.23; 1.47 and 1.01 miliequivalent.g-1, respectively for i, ir, ii and iir products.
Hydrous Tantalum Phosphates for Ion Exchange Purposes: A Systematic Study
Silva M.L.C.P.da,Silva G.L.J.P. da,Villela Filho D.N.
Materials Research , 2002,
Abstract: This work describes two methods of preparation of hydrous tantalum phosphates and their characterization as ion exchangers. The hydrous metallic phosphate compounds were chemically and physically characterized by thermal gravimetric analysis, X-ray diffractometry and surface area measurements. By the first method, tantalum phosphate was prepared by alkaline fusion of Ta2O5 with an excess of K2CO3, followed by lixiviation of the tantalate fusion product with hot water, and precipitation with diluted H3PO4. Preparation II was performed using metallic Ta dissolved in concentrated HF/HNO3 acidic mixture followed by hydrolysis of fluortantalic acid intermediary and precipitation with diluted H3PO4. Both freshly prepared materials (I and II) were exaustively refluxed with concentrated H3PO4, in its boiling point temperature, resulting respectively in Ta2O5. 2.1 H2O, (IR) and Ta2O5. 1.3 H2O, (IIR). Characterization of the prepared products have presented the following values: surface area of 108.27 ± 2.80; 220.14 ± 2.67; 117.07 ± 5.25 and 141.61 ± 0.27 m2.g-1 respectively for I, IR, II and IIR. All these materials were amorphous. The ion exchange behavior for all four hydrous tantalum phosphates was studied using Na+, K+ and Ba+2 as the exchanged species. The values for typical ion exchange capacity were 1.64; 1.23; 1.47 and 1.01 miliequivalent.g-1, respectively for I, IR, II and IIR products.
Penicillium restrictum lipases: A comparative study and characterization of enzymes with different degrees of purity
JESUS, M.F.C.P.;BRANCO, R.N.;SANT'ANNA JR, G.L.;FREIRE, D.M.G.;SILVA, J.G.;
Brazilian Journal of Chemical Engineering , 1999, DOI: 10.1590/S0104-66321999000200002
Abstract: penicillium restrictum was identified as a promising strain for lipase production due to enzyme production yield and thermal stability of the enzyme. this work presents results of lipase purification and enzyme stability versus ph. ultrafiltration and precipitation with ammonium sulphate were used as initial purification steps. the partially purified enzyme preparation showed an increase in stability as ph increased. the crude enzymatic preparation was assayed with different oils and tributirin and showed a major catalytic activity for triglycerides of medium/long-chain fatty acids. further purification steps were conducted on an analytical scale. the initial attempt to use gel filtration was abandoned as lipase lost its stability after this chromatographic procedure. the fast ion-exchange chromatography was performed on a mono q column, and two peaks with lipolytic activity were isolated and analysed by electrophoresis.
Prevalência da infec??o por lentivírus de pequenos ruminantes em caprinos em Teresina, Piauí
Sampaio Júnior, A.;Batista, M.C.S.;Cruz, M.S.P.;Silva, R.A.B.;Bona Nascimento, C.;Werneck, G.L.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2011, DOI: 10.1590/S0102-09352011000300032
Abstract: the prevalence of anti-lentiviruses antibodies of small ruminants was investigated in goat herds in the city of teresina, pi, brazil. a seroepidemiological survey was conducted involving 480 animals, apparently healthy, belonging to six rural properties. the diagnostic test was the agar gel immunodiffusion (agid), using antigens produced from cellular cultures infected with caprine arthritis encephalitis virus (caev cork). prevalences by gender and age were estimated considering sampling fractions for each farm. a general prevalence of 4.2%, was observerved, being 4.2% for females and 3.6% for males. prevalences were higher among older goats. regarding the breed standard, 23.5% were of the anglo nubian, 5.9% of the boer, 35.3% anglo nubian x boer crossbred, and 35.3% of undefined breed. it is concluded that small ruminant lentiviruses are endemic among goat herds of teresina.
A retractable barb needle for drug darts
G.L. van Rooyen,P.J. de Beer
Koedoe : African Protected Area Conservation and Science , 1973, DOI: 10.4102/koedoe.v16i1.892
Abstract: The mechanism and action of a new retractable barbneedle for drug darts are described. This dart needle is particularly successful in obviating unnecessary flight reactions andtrauma in darted animals, and facilitates the complete injection of the drug dose before the barb is retracted and the dart is dislogded from the animal. The whole process is completed within a few seconds and the expended dart can usually be retrieved in the immediate vicinity where the animal was darted.
Níveis de fibra em detergente neutro forrageiro na alimenta??o de ovelhas Santa Inês gestantes
Macedo Junior, G.L.;Fran?a, P.M.;Assis, R.M.;Almeida, T.R.V.;Paula, O.J.;Pérez, J. R.O.;Bai?o, A.A.F.;Borges, I.;Silva, V.B.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2009, DOI: 10.1590/S0102-09352009000100028
Abstract: the intake, apparent digestibility and feeding behavior of pregnant ewes ped diets containing different levels of neutral detergent fiber (ndf) were evaluated. sixteen santa inês ewes were randomly assigned to four treatments with 9, 17, 26 e 35% of ndf. dry matter (dm), organic matter, crude protein, crude energy, digestible energy and metabolizable energy intake were not affected by the level of ndf in the diet, however, ndf and acid detergent fiber (adf) intake increased with the increase of ndf diet levels. the apparent digestibility of the ndf and adf and rumination time increased with the ndf diet level. higher ndf diet levels influenced feeding behavior and apparent digestibility of ewes at the end of the lactation period.
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