971 resultados para metodo mae canguru
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Las proyecciones de la poblacion chilena se presentan por sexo y grupos quinquenales de edad, segun areas urbana y rural, para el total del pais y cada una de las 13 regiones respecto a los anos calendario comprendidos entre 1980 y 2000. Se incluyen indicadores demograficos para el pais por area. La poblacion total y rural fueron proyectadas segun el metodo de componentes. Se elaboraron para ello estimaciones de mortalidad, fecundidad y migracion por areas, planteandose hipotesis de su evolucion futura. La proyeccion urbana se obtuvo por diferencia. La distribucion por regiones se calculo mediante el metodo de la tabla cuadrada para cada area. La mortalidad y la fecundidad se estimaron para cada area por metodos indirectos. La proyeccion de la mortalidad por area se efectuo mediante el sistema logito interpolando con tablas limite. La fecundidad por area se proyecto utilizando la relacion entre la fecundidad rural y la del pais.
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In this work pellets containing chitosan for colonic drug delivery were developed. The influence of the polysaccharide in the pellets was evaluated by swelling, drug dissolution and intestinal permeation studies. Drug-loaded pellets containing chitosan as swellable polymer were coated with an inner layer of Kollicoat® SR 30 D and an outer layer of the enteric polymer Kollicoat® MAE 30 DP in a fluidized-bed apparatus. Metronidazole released from pellets was assessed using Bio-Dis dissolution method. Swelling, drug release and intestinal permeation were dependent on the chitosan and the coating composition. The drug release data fitted well with the Weibull equation, indicating that the drug release was controlled by diffusion, polymer relaxation and erosion occurring simultaneously. The film coating was found to be the main factor controlling the drug release and the chitosan controlling the drug intestinal permeation. Coated pellets containing chitosan show great potential as a system for drug delivery to the colon. © 2012 Elsevier Ltd.
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Different conditions of extraction using water, a methanol-water mixture and nitric acid solutions were evaluated for speciation of As(iii), As(v), DMA and MMA in plant samples that previously received As(v) after being sown and emergence was investigated. Microwave-assisted extraction (MAE) using diluted nitric acid solutions was also performed for arsenic extraction from chicken feed samples. The separation and determination of arsenic species were performed using HPLC-ICP-MS. The interference standard method (IFS) using 83Kr+ as the IFS probe was employed to minimize spectral interferences caused by polyatomic species, such as 40Ar 35Cl+. The extraction procedures tested presented adequate extraction efficiencies (90%), and the four arsenic species evaluated were found in plant samples. Extractions with diluted nitric acid solution at 90 °C were the most efficient strategy, with quantitative recoveries for all four As species in plant tissues. On the other hand, the methanol-water mixture was the solvent with the lowest extraction efficiency (50-60%). For chicken feed samples, MAE at 100 °C for 30 min resulted in an extraction efficiency of 97% and only As(v) was found, without any species interconversion. The IFS method contributed to improving precision and limits of detection and quantification for all tested extraction procedures. Significant improvements on accuracy were obtained by applying the IFS method and recoveries between 77 and 94%, and 82 and 93% were obtained for plant extracts and chicken feed samples, respectively. This journal is © 2013 The Royal Society of Chemistry.
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Pós-graduação em Artes - IA
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Pós-graduação em Artes - IA
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Pós-graduação em Artes - IA
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Pós-graduação em Artes - IA
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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