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Search Results: 1 - 10 of 717669 matches for " G.L.J.P. da;Villela Filho "
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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.
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.
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, 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).
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).
Psychopharmacotherapy of panic disorder: 8-week randomized trial with clonazepam and paroxetine
Nardi, A.E.;Valen?a, A.M.;Freire, R.C.;Mochcovitch, M.D.;Amrein, R.;Sardinha, A.;Levitan, M.N.;Nascimento, I.;de-Melo-Neto, V.L.;King, A.L.;de O. e Silva, A.C.;Veras, A.B.;Dias, G.P.;Soares-Filho, G.L.;da Costa, R.T.;Mezzasalma, M.A.;de Carvalho, M.R.;de Cerqueira, A.C.;Hallak, J.E.;Crippa, J.A.;Versiani, M.;
Brazilian Journal of Medical and Biological Research , 2011,
Abstract: the objective of the present randomized, open-label, naturalistic 8-week study was to compare the efficacy and safety of treatment with clonazepam (n = 63) and paroxetine (n = 57) in patients with panic disorder with or without agoraphobia. efficacy assessment included number of panic attacks and clinician ratings of the global severity of panic disorders with the clinical global impression (cgi) improvement (cgi-i) and cgi severity (cgi-s) scales. most patients were females (69.8 and 68.4% in the clonazepam and paroxetine groups, respectively) and age (mean ± sd) was 35.9 ± 9.6 years for the clonazepam group and 33.7 ± 8.8 years for the paroxetine group. treatment with clonazepam versus paroxetine resulted in fewer weekly panic attacks at week 4 (0.1 vs 0.5, respectively; p < 0.01), and greater clinical improvements at week 8 (cgi-i: 1.6 vs 2.9; p = 0.04). anxiety severity was significantly reduced with clonazepam versus paroxetine at weeks 1 and 2, with no difference in panic disorder severity. patients treated with clonazepam had fewer adverse events than patients treated with paroxetine (73 vs 95%; p = 0.001). the most common adverse events were drowsiness/fatigue (57%), memory/concentration difficulties (24%), and sexual dysfunction (11%) in the clonazepam group and drowsiness/fatigue (81%), sexual dysfunction (70%), and nausea/vomiting (61%) in the paroxetine group. this naturalistic study confirms the efficacy and tolerability of clonazepam and paroxetine in the acute treatment of patients with panic disorder.
Evolu??o do peso testicular de cordeiros da ra?a Santa Inês alimentados com diferentes níveis de energia
Assis, R.M.;Pérez, J.R.O.;Barreto Filho, J.B.;De Paula, O.J.;Almeida, T.R.V.;Macedo Junior, G.L.;Fran?a, P.M.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2008, DOI: 10.1590/S0102-09352008000500026
Abstract: the development of the testicule weight of santa inês lambs, fed different energy levels, was evaluated. sixty-four lambs were distributed in four treatments: a - 8.7%; b - 17.3%; c - 26.0% and d - 34.7% of neutral detergent fiber (ndf) supplied by the diet forage, determining the variation of the metabolizable energy intake. four animals from each treatment were slaughtered at pre-defined ages of 43 days, 83 days, 123 days and 173 days. after slaughtering, the testicles were separated from the epididimous and individually weighted. the animals fed diets a and b presented higher metabolizable energy intake (14.11mcal/lw0.75), higher live weight (18.89kg and 17.09kg, respectively) and higher testicules weight (62.54g and 27.16g, respectively), indicating that the testicular development is highly dependent on the body development and the quantity of metabolizable energy intake. the prediction of the testicules weight by the scrotal circumference showed to be more efficient than the age or the live weight of the animals.
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.
Neonatal handling induces anovulatory estrous cycles in rats
Gomes C.M.,Frantz P.J.,Sanvitto G.L.,Anselmo-Franci J.A.
Brazilian Journal of Medical and Biological Research , 1999,
Abstract: Since previous work has shown that stimulation early in life decreases sexual receptiveness as measured by the female lordosis quotient, we suggested that neonatal handling could affect the function of the hypothalamus-pituitary-gonadal axis. The effects of neonatal handling on the estrous cycle and ovulation were analyzed in adult rats. Two groups of animals were studied: intact (no manipulation, N = 10) and handled (N = 11). Pups were either handled daily for 1 min during the first 10 days of life or left undisturbed. At the age of 90 days, a vaginal smear was collected daily at 9:00 a.m. and analyzed for 29 days; at 9:00 a.m. on the day of estrus, animals were anesthetized with thiopental (40 mg/kg, ip), the ovaries were removed and the oviduct was dissected and squashed between 2 glass slides. The number of oocytes of both oviductal ampullae was counted under the microscope. The average numbers for each phase of the cycle (diestrus I, diestrus II, proestrus and estrus) during the period analyzed were compared between the two groups. There were no significant differences between intact and handled females during any of the phases. However, the number of handled females that showed anovulatory cycles (8 out of 11) was significantly higher than in the intact group (none out of 10). Neonatal stimulation may affect not only the hypothalamus-pituitary-adrenal axis, as previously demonstrated, but also the hypothalamus-pituitary-gonadal axis in female rats.
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