959 resultados para Macro-mesoporous aluminas
Resumo:
Incluye Bibliografía
Resumo:
Incluye Bibliografía
Resumo:
Incluye Bibliografía
Resumo:
Includes bibliography
Resumo:
Hace algunas observaciones respecto de los principales acontecimientos macroeconomicos en Trinidad y Tabago desde 1973, y procura insertar el desempeno del sector agricola en ese contexto.
Resumo:
The study of growth and uptake of nutrients is important to determine the times of increased demand in order to schedule the fertigation. The present research was developed with the objective of evaluating the effects of different levels of electrical conductivity on growth and accumulation of nutrients in chrysanthemum plants under greenhouse conditions. The electrical conductivity levels on the applied solution were 1.42, 1.65, 1.89, 2.13 and 2.36 dS m-1 (bud vegetative stage); 1.71, 1.97, 2.28, 2.57 and 2.85 dS m-1 (bud stage). The dry mass of the aerial portion of the plant and the contents of macronutrients and micronutrients were determined every 14 days. The nutrient accumulation in chrysanthemum plant showed similar trend as compared to dry matter accumulation. The nutrients presented the following order of absorption: K>N>Ca>Mg>P>S (1425, 892, 184, 150, 110 and 59 mg plant-1) and Fe>Zn>B>Mn>Cu (2254, 2219, 1725, 1287, 210 μg plant-1). The content of most nutrients increased with increase in electrical conductivity of the solution, without salt effect up to EC of 2.85 dS m-1.
Resumo:
The statement starts with a balance of the 15-years period of the economic reforms occurred in the region, up to the Mexican financial crisis in 1995. The main lesson to be drawn from this period refers to the need of supplementing and reinforcing macro-economic policy, together with the application of public policy measures at the micro-, meso-, and institutional levels, in order to support productive modernization, the development of financial and labour markets and the establishment or strengthening of institutions which can help to create an environment conducive to development. Further on, the statement explains the strategies proposed by ECLAC for overcoming the obstacles to accelerated growth within a framework of stability, social equity and democracy. These refer to expanding gross domestic product, increasing productivity and providing more and better jobs. In order to achieve this goal it is necessary to ensure macroeconomic equilibria in its broader sense, raise the level of national saving and channel it into productive investment, as well as an accelerated and systematic incorporation of production and management techniques designed to raise productivity in a growing number of firms. In the last part, the statement refers to the situation of the United Nations and honors the memory of Dr. Raúl Prebisch, on the tenth anniversary of his death.
Resumo:
Includes bibliography
Resumo:
La exposición se inicia con un balance de los quince años de reformas económicas transcurridos en la región hasta la crisis financiera mexicana de 1995. La principal enseñanza que puede obtenerse del período se refiere a la necesidad de complementar y reforzar la política macroeconómica con la aplicación de medidas de política pública a nivel microeconómico, mesoeconómico e institucional, para apoyar la modernización productiva, el desarrollo de los mercados financieros y laborales y la creación o consolidación de instituciones que contribuyan a crear un ambiente propicio al desarrollo. A continuación se exponen las principales orientaciones de la estrategia de desarrollo propuesta por la CEPAL, destinadas a superar los obstáculos que impiden acelerar el crecimiento, en un marco de estabilidad, equidad y democracia. Estas se refieren a los objetivos de expansión del producto, aumento de la productividad y generación de empleo. Para conseguirlos se plantea la necesidad de mantener los equilibrios macroeconómicos en su sentido amplio, de lograr un aumento del ahorro nacional y su canalización hacia inversiones productivas, y de obtener una acelerada y sistemática incorporación de técnicas de producción y de gestión tendientes a elevar la productividad de un número creciente de empresas. En la última parte se refiere a la situación de Naciones Unidas y rinde homenaje a la memoria de Raúl Prebisch, quien falleciera hace diez años.
Resumo:
Incluye Bibliografía
Resumo:
The catalytic properties of monomodal microporous and bimodal micro-mesoporous zeolites were investigated in the gas-phase dehydration of glycerol. The desilication methodology used to produce the mesoporous zeolites minimized diffusion limitations and increased glycerol conversion in the catalytic reaction due to the hierarchical system of secondary pores created in the zeolite crystals. The chemical and structural properties of the catalyst were studied by X-ray diffraction, nitrogen adsorption-desorption isotherms, NH3-TPD and pyridine chemisorption followed by IR-spectroscopy. Although the aim was to desilicate to create mesoporosity in the zeolite crystals, the desilication promoted the formation of extra-framework aluminum species that affected the conversion of glycerol and the products distribution. The results clearly show that the mesoporous zeolites with designed mesopore structure allowed a rapid diffusion and consequently improved the reaction kinetics. However, especial attention must be given to the desilication procedure because the severity of the treatment negatively interfered on the Brønsted and Lewis acid sites relative concentration and, consequently, in the efficiency of the catalysis performed by these materials. On the other hand, during the catalytic reaction, the intracrystalline mesopores allowed carbonaceous compounds to be deposited herein, resulting in less blocked micropores and catalysts with higher long-term stability.
Resumo:
The aim of this work was the preparation of inorganic mesoporous materials from silica, calcium phosphate and a nonionic surfactant and to evaluate the incorporation and release of different concentrations of osteogenic growth peptide (OGP) for application in bone regeneration. The adsorption and release of the labeled peptide with 5,6-carboxyfluorescein (OGP-CF) from the mesoporous matrix was monitored by fluorescence spectroscopy. The specific surface area was 880 and 484 m2 g- 1 for pure silica (SiO) and silica/apatite (SiCaP), respectively; the area influenced the percentage of incorporation of the peptide. The release of OGP-CF from the materials in simulated body fluid (SBF) was dependent on the composition of the particles, the amount of incorporated peptide and the degradation of the material. The release of 50% of the peptide content occurred at around 4 and 30 h for SiCaP and SiO, respectively. In conclusion, the materials based on SiO and SiCaP showed in vitro bioactivity and degradation; thus, these materials should be considered as alternative biomaterials for bone regeneration. © 2013 Elsevier B.V.
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)