989 resultados para 1.0-1.1 phi
Resumo:
The microwave dielectric properties of (I -x)CaTiO3-xSm(Mg1/2Tit,2)O3(0.1 <-x< 1.0) have been investigated. The system forms a solid solution throughout the entire compositional range. The dielectric constant decreases from 86 to 25 as x varies from 0.1 to 1.0. The Qxf varies non-linearly and increases for composition with x> 0.6. The nonmonotonic variation with composition x is more pronounced in Tt than in er. The microwave dielectric properties indicate the possibility of a phase transformation for x between 0.4 and 0.5
Resumo:
The reaction of aniline with methanol was carried out over Zn1-xNixFe2O4 (x= 0, 0.2, 0.5, 0.8 and 1) type systems in a fixed-bed down-flow reactor. It was observed that systems possessing low ``x'' values are highly selective and active for mono N-alkylation of aniline leading to N-methyl aniline. Selectivity for N-methyl aniline over ZnFe2O4 was more than 99% under the optimized reaction conditions. Even at methanol to aniline molar ratio of 2, the yield of N-methyl aniline was nearly 55.5%, whereas its yield exceeded 67% at the molar ratio of 7. The Lewis acid sites of the catalysts are mainly responsible for the good catalytic performance. Cation distribution in the spinel lattice influences their acido-basic properties, and hence, these factors have been considered as helpful to evaluate the activity and stability of the systems.
Selective N-monomethylation of aniline using Zn1-x CoxFe2O4( x=0, 0.2, 0.5, 0.8 and 1.0)type systems
Resumo:
A series of ferrites having the general formula Zn1-xCoxFe2O4 (x=0, 0.2, 0.5, 0.8 and 1.0)were prepared by soft chemical route. The materials were characterized by adopting various physico-chemical methods. The reaction of aniline with methanol was studied in a fixed-bed reactor system as a potential source for the production of various methyl anilines. It was observed that systems possessing low ‘ x’ values are highly selective and active for N-monoalkylation of aniline leading to N-methylaniline. Reaction parameters were properly varied to optimize the reaction conditions for obtaining N-methylaniline selectively and in better yield. Among the systems Zn0.8Co0.2Fe2O4 is remarkable due to its very high activity and excellent stability. Under the optimized conditions N-methylaniline selectivity exceeded 98%. Even at a methanol to aniline molar ratio of 2, the yield of N-methylaniline was nearly 50%, whereas its yield exceeded 71% at the molar ratio of 5. ZnFe2O4, though executed better conversion than Zn0.8Co0.2Fe2O4 in the initial period of the run, deactivates quickly as the reaction proceeds. The Lewis acidity of the catalysts is mainly responsible for the good performance. Cation distribution in the spinel lattice influences their acido-basic properties and, hence, these factors have been considered as helpful parameters to evaluate the activity of the systems.
Resumo:
Preparation of simple and mixed ferrospinels of nickel, cobalt and copper and their sulphated analogues by the room temperature coprecipitation method yielded fine particles with high surface areas. Study of the vapour phase decomposition of cyclohexanol at 300 °C over all the ferrospinel systems showed very good conversions yielding cyclohexene by dehydration and/or cyclohexanone by dehydrogenation, as the major products. Sulphation very much enhanced the dehydration activity over all the samples. A good correlation was obtained between the dehydration activities of the simple ferrites and their weak plus medium strength acidities (usually of the Brφnsted type) determined independently by the n-butylamine adsorption and ammonia-TPD methods. Mixed ferrites containing copper showed a general decrease in acidities and a drastic decrease in dehydration activities. There was no general correlation between the basicity parameters obtained by electron donor studies and the ratio of dehydrogenation to dehydration activities. There was a leap in the dehydrogenation activities in the case of all the ferrospinel samples containing copper. Along with the basic properties, the redox properties of copper ion have been invoked to account for this added activity.
Resumo:
Resumen tomado de la publicación. Incluye imágenes de capturas de pantalla del ordenador de las herramientas desarrolladas en este curso. El manual viene acompañado de los recursos necesarios para realizar las actividades prácticas
Resumo:
Resumen tomado de la publicación. Incluye capturas de pantalla de ordenador de dicho editor. Este documento está sujeto a una licencia de Reconocimiento-No Comercial-Compartir con la misma licencia 3.0 España de Creative Commons
Resumo:
Resumen tomado de la publicación. Incluye imágenes de capturas de pantalla del ordenador
Resumo:
Resumen tomado de la publicación. Incluye imágenes de capturas de pantalla del ordenador que refuerzan las explicaciones del curso
Resumo:
Programa de simulación sobre MS-DOS destinado a Ciencias Naturales en Secundaria. Consiste en un software que simula el cruce entre diferentes individuos de 'musca virtualis' con ocho equivalentes informáticos de cromosomas. Así el emparejamiento de ejemplares permite al programa mostrar la forma, el fenotipo de mosca, generado en la descendencia. Por otra parte incorpora un programa auxiliar que permite al profesorado crear nuevos individuos que agregar al abanico de posibles combinaciones. Anexa manuales de uso de ambos programas generados a posteriori, en 1996.
Resumo:
Se trata de unos talleres que experimenta con las sensaciones y exploran los sentidos del gusto, el tacto, la vista y el olfato. Su objetivo se centra en estimular los diferentes sentidos y sacarles provecho creando diferentes sensaciones, favoreciendo la capacidad de atención e impulsando el desarrollo general. El resultado es que el niño o la niña además de explorar los diferentes sentidos, tiene en cuenta otro tipo de materiales, adquiere autonomía, capacidad de concentración y mejora la convivencia.
Resumo:
Material no publicado
Resumo:
El trabajo está destinado al desarrollo cognitivo de niños de Educación Infantil con necesidades educativas especiales. Obtuvo la quinta mención de la modalidad B en el XII Certamen de Materiales Curriculares de 2004, organizado por la Consejería de Educación de la Comunidad de Madrid. Consta de un manual y un CD-ROM. El material impreso presenta los objetivos, contenidos y metodología del trabajo. Además, incluye orientaciones técnicas sobre Windows y sobre la aplicación AMPARO (Actividades de Memoria, Percepción, Atención, el Razonamiento y la Orientación). El CD-ROM contiene el material original en distintos formatos, sxw, sdw, doc y html y más de 500 actividades distribuidas en cuatro niveles, de menor a mayor dificultad, en las que se trabaja con imágenes de animales a la vez que se introducen conceptos cada vez más complejo.
Resumo:
Este trabajo obtuvo el primer premio de la modalidad A de los Premios Joaquín Sama 2005. El enlace html es el mismo para los documentos con códigos 00920063000155, 00920063000156 y 00920063000157