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Search Results: 1 - 10 of 24099 matches for " Ant?nio Augusto;Queiroz "
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Otimiza??o e valida??o da técnica de extra??o líquido-líquido com parti??o em baixa temperatura (ELL-PBT) para piretróides em água e análise por CG
Vieira, Heulla Pereira;Neves, Antnio Augusto;Queiroz, Maria Eliana Lopes Ribeiro de;
Química Nova , 2007, DOI: 10.1590/S0100-40422007000300006
Abstract: the liquid-liquid extraction with the low temperature partition technique was developed for the analysis of four pyrethroids in water by cg. using a factorial design the extraction technique was optimised evaluating the effect of the variables ionic strength, contact time and proportion between sample and solvent volumes. the validation parameters sensitivity, precision, accuracy and detection and quantification limits were evaluated. the lod and loq of the method varied from 1.1 to 3.2 μg l-1 and 2.7 to 9.5 μg l-1, respectively.
Influência da matéria organica na adsor??o do fungicida triadimenol pelo solo
Lopes, Nilva Pereira;Queiroz, Maria Eliana Lopes Ribeiro de;Neves, Antnio Augusto;Zambolim, Laércio;
Química Nova , 2002, DOI: 10.1590/S0100-40422002000400006
Abstract: the adsorption of triadimenol (1-(4-chlorophenoxy)-3,3-dimethyl-1-(1h-1,2,4-triazol-1-yl)butan-2-ol) on soil samples with varying contents of organic matter was studied. the adsorption was described by means of the freundlich's isoterm. an increase in the capacity of adsorption was observed as the content of organic carbon in the matrix increased. that effect was observed when removing the organic matter from the soil, when adding a urban waste compost to the soil sample as well as to the soil sample without organic matter, and also after leaving proportions of urban waste compost incubated in these matrices for a period of 120 days. the results show that the adsorption of the triadimenol in the soil is dependent of its content of organic carbon.
Doses de fósforo no estabelecimento de capim-xaraés e estilosantes Mineir?o em consórcio
Lopes, Jalison;Evangelista, Antnio Ricardo;Pinto, José Cardoso;Queiroz, Domingos Sávio;Muniz, Joel Augusto;
Revista Brasileira de Zootecnia , 2011, DOI: 10.1590/S1516-35982011001200007
Abstract: the objective of this study was to evaluate the effect of the application of phosphorus on the establishment of stylosanthes guianensis cv. mineir?o and brachiaria brizantha cv. xaraés mixed. the experiment was installed in an area of 8,000 m2, divided into 24 plots of 333.3 m2. the phosphorus doses utilized in the establishment of pasture were 25, 50, 100 and 200 kg/ha of p2o5. the evaluations were made 65 days after sowing. the experimental design was a randomized blocks design with three replications and the treatment with two replicates per block. the highest rates of increase in the length of the leaf blade and tillering of xaraés grass, leaflet length, leaflet width and height of the legume occurred from 25 to 50 kg/ha of p2o5. the highest rates of increase in the width of the leaf blade and tiller height of xaraés grass occurred from 25 to 100 kg/ha of p2o5. number of plants of mineir?o stylo was higher with fertilization with 44 kg/ha of p2o5 and decreased drastically with phosphate. phosphate fertilizers establishing 44 kg/ha p2o5 provide better establishment of the intercropped pasture. nevertheless, further studies are required to determine the degree of compatibility between the two species and the viability of intercropping. application of growing levels of phosphorus in an intercropping system provides increase in the rates of accumulation of dry matter of xaraés grass and accumulation of total dry matter during the first dry period post-establishment of the pasture.
Influência da matéria organica na adsor o do fungicida triadimenol pelo solo
Lopes Nilva Pereira,Queiroz Maria Eliana Lopes Ribeiro de,Neves Antnio Augusto,Zambolim Laércio
Química Nova , 2002,
Abstract: The adsorption of triadimenol (1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol) on soil samples with varying contents of organic matter was studied. The adsorption was described by means of the Freundlich's isoterm. An increase in the capacity of adsorption was observed as the content of organic carbon in the matrix increased. That effect was observed when removing the organic matter from the soil, when adding a urban waste compost to the soil sample as well as to the soil sample without organic matter, and also after leaving proportions of urban waste compost incubated in these matrices for a period of 120 days. The results show that the adsorption of the triadimenol in the soil is dependent of its content of organic carbon.
Determina o de resíduos de organoclorados em águas fluviais do município de Vi osa - MG
Chagas Cíntia Maria,Queiroz Maria Eliana Lopes Ribeiro de,Neves Antnio Augusto,Queiroz José Humberto de
Química Nova , 1999,
Abstract: In this work the contamination, by organochlorinated, of a drinking water source located in the region of Vi osa, MG, was evaluated. The identification and quantification of the analytes was carried out using a gas-chromatograph equipped with an electron capture detector after liquid-liquid extraction and concentration. Four insecticides, Aldrin, Epoxy heptachloride, Endrin and op'- DDT were detected in concentrations that are higher than the safety limits established in the Brazilian legislation.
Fracionamento dos carboidratos e cinética de degrada o in vitro da fibra em detergente neutro da extrusa de bovinos a pasto
Vieira Ricardo Augusto Mendon?a,Pereira José Carlos,Malafaia Pedro Antnio Muniz,Queiroz Augusto César de
Revista Brasileira de Zootecnia , 2000,
Abstract: Os objetivos do presente trabalho foram a caracteriza o e a determina o das estimativas dos parametros relativos à cinética de degrada o ruminal dos carboidratos, em amostras de extrusa de animais mantidos em pastagem natural da Zona da Mata (MG), nas esta es chuvosa e seca do ano. Para obten o de amostras representativas, foram usados quatro animais fistulados no es fago durante dois períodos experimentais na esta o chuvosa, e três destes animais por dois períodos experimentais na esta o seca, do ano de 1996. Foi efetuado o fracionamento dos carboidratos de acordo com o sistema Cornell e determinadas as taxas de degrada o da fibra em detergente neutro (FDN), a partir dos perfis de degrada o in vitro deste componente. Foram determinadas as fra es potencialmente degradável (B2) e indegradável (C) da FDN, corrigida para proteína e cinzas, e as taxas de latência dinamica, degrada o e crescimento específico dos microrganismos, a partir da fra o B2, além dos coeficientes de degradabilidade e do efeito de reple o ruminal da FDN. Observou-se que os carboidratos n o-estruturais compreenderam pequena fra o dos carboidratos totais nas amostras do pasto, em ambas as esta es. Os carboidratos estruturais foram responsáveis pelo aumento no teor de carboidratos totais da extrusa, com a mudan a da esta o chuvosa para a esta o seca; contudo, por causa do aumento da fra o C e da menor taxa de crescimento específico dos microrganismos durante a esta o seca, foi possível notar redu o da degradabilidade e aumento do efeito de reple o ruminal da FDN da extrusa.
Simula o da dinamica de nutrientes no trato gastrintestinal: aplica o e valida o de um modelo matemático para bovinos a pasto
Vieira Ricardo Augusto Mendon?a,Pereira José Carlos,Malafaia Pedro Antnio Muniz,Queiroz Augusto Cesar de
Revista Brasileira de Zootecnia , 2000,
Abstract: O objetivo do presente trabalho foi a valida o das predi es da dinamica ruminal e pós-ruminal dos nutrientes e do crescimento microbiano no rúmen, usando as equa es do sistema Cornell. O experimento foi realizado durante as esta es chuvosa e seca do ano de 1996, em uma área de pastagem natural localizada no município de Vi osa (MG). Foram utilizados novilhos canulados no es fago, rúmen e abomaso, durante dois períodos experimentais em cada esta o, e usados indicadores externos (Cr2O3 e Eu) para estimativa do consumo e da taxa de passagem da digesta no rúmen. Foram determinados os fluxos de nitrogênio total e de nitrogênio bacteriano no abomaso, os carboidratos totais e estruturais digeridos no rúmen e os teores em nutrientes digeríveis totais. Estas variáveis também foram preditas a partir do modelo descrito no sistema Cornell, para valida o de suas estimativas. Verificou-se que o modelo foi sensível às estimativas das taxas de passagem, superestimou (12,38%) o fluxo de nitrogênio bacteriano no abomaso e subestimou (70,64%) a disponibilidade ruminal dos carboidratos estruturais. O emprego da taxa de passagem de 0,02 h-1 no cálculo das estimativas resultou no aumento da superestima o do fluxo de N de origem bacteriana (28,66%), em virtude da maior degrada o dos carboidratos estruturais, cuja estimativa permaneceu subestimada em 21,55%. A redu o do consumo de matéria seca foi mais bem correlacionada aos teores de FDN indigerível que aos teores de FDN, devendo-se ressaltar que a capacidade diária de consumo desta fra o foi de 0,6% do peso vivo e n o diferiu entre esta es.
Evaluation of pesticide adsorption in gas chromatographic injector and column
Pinho, Gevany Paulino de;Silvério, Flaviano Oliveira;Neves, Antnio Augusto;Queiroz, Maria Eliana Lopes Ribeiro de;
Química Nova , 2012, DOI: 10.1590/S0100-40422012000400016
Abstract: components in complex matrices can cause variations in chromatographic response during analysis of pesticides by gas chromatography. these variations are related to the competition between analytes and matrix components for adsorption sites in the chromatographic system. the capacity of the pesticides chlorpyrifos and deltamethrin to be adsorbed in the injector and chromatographic column was evaluated by constructing three isotherms and changing the column heating rate to 10 and 30 oc min-1. by using ancova to compare the slope of calibration graphs, results showed that the higher the injector temperature (310 oc) the lower the pesticide adsorption. also, deltamethrin influenced the adsorption of chlorpyrifos on the column chromatographic.
Desenvolvimento de metodologia para determina??o de piretroides em manteiga
Marthe, Deyse de Brito;Bittencourt, Leila Moreira;Queiroz, Maria Eliana Lopes Ribeiro de;Neves, Antnio Augusto;
Química Nova , 2010, DOI: 10.1590/S0100-40422010000600030
Abstract: the objective of this study was to evaluate the use of the matrix solid-phase dispersion technique associated with purification at low temperature for the determination of pyrethroids in butter. evaluated parameters included: sample/adsorbent ratio, type of adsorbent and extractor solvent. the optimized method was validated based on predetermined requirements. the detection limits of the pyrethroids cypermethrin and deltamethrin were 0.082 and 0.11 μg g-1, and quantification limit were 0.28 and 0.32 μg g-1, respectively, with extraction percentages near 90% and coefficients of variation less than of 10%..
Interferência do acido ascórbico na determina??o de a?úcares redutores pelo método de Lane e Eynon
Tavares, José Torquato de Queiroz;Cardoso, Ricardo Luis;Costa, Jo?o Albany;Fadigas, Francisco de Souza;Fonseca, Antnio Augusto;
Química Nova , 2010, DOI: 10.1590/S0100-40422010000400008
Abstract: two studies, both set up as completely randomized design, in a 5x5 and 7x5 factorial schemes, evaluated the interference of 5 and 7 ascorbic acid concentrations and 5 glucose or 5 sucrose concentrations, respectively, on the determination of total and reducing sugars by lane and eynon method. the ascorbic acid reducing power (aarp) over the fehling liquor interfered in the results of total and reducing sugars. on average the aarp was equivalent to 74.83 and 69.71% of the reducing power of glucose and of hydrolyzed sucrose, respectively. the ascorbic acid was stable in all study conditions.
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