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Search Results: 1 - 10 of 805400 matches for " M.L.C.P.da;Silva "
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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).
Capilaroscopia panoramica periungueal e sua aplica o em doen as reumáticas
Silva L.S.M. da,Lima A.R.A.G.,Pucinelli M.L.C.,Atra E.
Revista da Associa??o Médica Brasileira , 1997,
Abstract:
Paroxysmal dystonia and neuromyelitis optica
Schmidt, Felipe R.;Costa, Flavio Henrique R.;Silva, Fernanda M.L.C.;Maultasch, Henryk;Rosso, Ana Lucia;Nicaretta, Denise H.;Mattos, James P. de;Novis, Sergio A.P.;Alves-Leon, Soniza V;
Arquivos de Neuro-Psiquiatria , 2012, DOI: 10.1590/S0004-282X2012005000011
Abstract: paroxysmal dyskinesias (pd) are thought to be rare movement disorders. the overwhelming majority of reported cases are primary. secondary pd has seen reported to occur in some conditions, mainly in multiple sclerosis and head trauma. the anatomic origin of the lesion is also rarely seen at the spinal cord. our objective was to describe four patients with paroxysmal dystonia secondary to spinal lesions during the recovering phase of a neuromyelitis optica (nmo) bout. in the reviewed literature, we do not find any report of pd related to nmo.
Soil organisms associated to the weed suppressant Crotalaria juncea (fabaceae) and its importance as a refuge for natural enemies
Tavares, W.S;Cruz, I;Silva, R.B;Figueiredo, M.L.C;Ramalho, F.S;Serr?o, J.E;Zanuncio, J. C;
Planta Daninha , 2011, DOI: 10.1590/S0100-83582011000300001
Abstract: soil organisms play an important role in organic crops of crotalaria juncea (fabaceae) and are associated with the natural conservation of the environment. the present study was aimed to investigate the population of soil organisms in the organic culture of c. juncea, as well as its importance as a refuge for natural enemies. dalbulus maidis (hemiptera: cicadellidae), diabrotica sp. (coleoptera: chrysomelidae), doru luteipes (dermaptera: forficulidae), gryllus assimilis (orthoptera: gryllidae), lagria villosa (coleoptera: lagriidae), melanotus sp. (coleoptera: elateridae), meloidogyne incognita (tylenchida: heteroderidae), nephila clavipes (araneae: nephilidae), orius insidiosus (hemiptera: anthocoridae), pheidole sp. (hymenoptera: myrmicidae), phyllophaga sp. (coleoptera: scarabeidae), procornitermes sp. (isoptera: termitidae), solenopsis sp. (hymenoptera: formicidae), and utetheisa ornatrix (lepidoptera: arctiidae) were identified in c. juncea. the organisms that were found during a 3-month period in 144 trenches in c. juncea were pest species (84.47%) and natural enemies (15.53%) as well. natural enemies had an average of 11.89 individuals per 1.08 m3 of soil cultivated with c. juncea. the abundance of organisms in the pod stage (5.49%) of c. juncea was lower than that in the vegetative (83.50%) and flowering (11.01%) stages. crotalaria juncea plants can be used as part of a crop system for integrated pest management.
Varia??o dos componentes da produ??o de dois cultivares de soja, UFV-1 e IAC-7, em fun??o da época de semeadura
Nogueira, S.S.S.;Haag, H.P.;Carelli, M.L.C.;Fahl, J.L.;Maeda, J.A.;
Anais da Escola Superior de Agricultura Luiz de Queiroz , 1984, DOI: 10.1590/S0071-12761984000100008
Abstract: a study was made on early, normal and delayed planting dates on the seed yield and its components of two late varieties of soybean, ufv-1 and iac-7. the field experiment was carried out at campinas experimental station in eutrophic latossolo roxo during the years 1979/80 and 1980/81. in the first year planting were made every twenty days starting from october 5 and in the second year every thirty days starting from september 17, the total being eight and seven in the consecutive years. the parameters studied were: seed yield, nodes/ /plant, podes/plant and seed weight. the planting dates affected the seed yield and its components in both varieties. the number of nodes and pods/plant were more affected than the seed weight. each variety had the same behavior with regard to the number of nodes and pods/plant and the same cannot be said to seed weight. in the first year the seed weight was not affected by the planting date and in the second, late plantings decreased the values of this parameter. the variability of yield components was more effective for highest yields planting dates. number of nodes and pods/plant exercised a greater influence on the seed yield than the seed weight.
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