724 resultados para catálise homogênea


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La neumonía es de las primeras 20 causas de ingreso hospitalario en el Instituto Salvadoreño del Seguro Social (ISSS) según reporte epidemiológico 2012 y por lo tanto una de las patologías en las que más se invierten recursos económicos por el alto costo de antibióticos y estancia hospitalaria. Al momento no se disponen de normas o guías institucionales actualizadas a fin de optimizar recursos, brindar tratamiento adecuado y acortar estancias hospitalarias o complicaciones tempranas. El tratamiento antibiótico inicial de la neumonía es generalmente empírico, dado que raramente se conoce el agente etiológico al momento del diagnóstico. La indicación del antibiótico debe hacerse teniendo en cuenta los datos clínicos, los antecedentes personales del paciente y los datos epidemiológicos. Se realizó un estudio observacional, descriptivo de corte transversal a lo largo de 3 meses, agosto a octubre 2013, tomando como población de estudio todo paciente que ingresó en el período estipulado en los Hospitales Médico Quirúrgico (HMQ) y Hospital General (HG) del Instituto Salvadoreño del Seguro Social, y como muestra a 134 pacientes que fue la misma población total de estudio, para su posterior clasificación y verificación del tratamiento inicial instaurado, y conocer la adherencia de éste con respecto a lo descrito en guías de manejo internacionales. Del total de pacientes la mayoría de casos en ambos hospitales fue clasificado como Neumonía Adquirida en la Comunidad (NAC) con el 61% (82 pacientes), en cuanto a la Neumonía Nosocomial ocupó el segundo lugar en frecuencia en el Hospital General con un 19.7% (14 pacientes) y la Neumonía Asociada a los Cuidados de la Salud solo el 8.4% (6 casos). Esta situación fue diferente en el Hospital Médico Quirúrgico ya que se encontró que la Neumonía Asociada a los Cuidados de la Salud presentó una cantidad significativa de casos representada por 39.6% (25 pacientes) mientras que la Neumonía Nosocomial únicamente representó el 11% de casos (7 pacientes). En ambos hospitales la doble antibioticoterapia con Ceftriaxona y Claritromicina fue el tratamiento inicial instaurado en la mayoría de los casos de Neumonía Adquirida en la Comunidad, mientras que el Cefepime fue el más utilizado para Neumonías Nosocomiales y Neumonías Asociadas a los Cuidados de la Salud. Al comparar la adherencia a las guías internacionales de tratamiento antibiótico, en los diferentes tipos de neumonías, ésta fue de un 73.8%, en ambos Hospitales de las cuales el 76% corresponde a casos tratados en Hospital General y un 71% al Hospital Médico Quirúrgico; en los tipos de neumonías que hubo mayor adherencia fue en la asociada a cuidados de la salud y nosocomial. La menor adherencia al tratamiento antibiótico inicial recomendado se encontró en la NAC; en el Hospital General se encontró un 68.6% de adherencia mientras que en el HMQ un 51.6%. Por lo que podemos concluir que en más del 70% de los casos de los pacientes del estudio se indicó el antibiótico inicial recomendado por guías internacionales para el tratamiento de los diferentes tipos neumonía. Es conveniente actualizar las guías institucionales de manejo para ésta entidad y su posterior difusión a los médicos tratantes con el objetivo de brindar una atención homogénea acorde a guías actualizadas internacionales.

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Biodiesel is an alternative diesel fuel that is produced from vegetable oils and animal fats. Currently, most biodiesel is made from oils, methanol, and an alkaline catalyst. Conventional catalysts is commonly used for catalyzing esterification of fatty acid to produce biodiesel. However, a better and greener method was found. An ionic liquid (IL) is a molten salt consisting of a cation and an anion, with low melting temperature. It offers a better solution than sulfuric acid, because it can be recycled and reused in subsequent runs after recovery steps. In this study, a Brønsted acidic IL, 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]) was used as a catalyst in the esterification of oleic acid with methanol into biodiesel. The effect of different operation parameters such as methanol to oil molar ratio, amount of catalyst, reaction temperature, and reaction time were tested. The optimum conditions for esterification of oleic acid were identified as oleic acid/methanol molar ratio of 1/10, amount of catalyst 10 wt%, reaction time of 4 h, and reaction temperature of 90oC. FAME content of produced biodiesel was analyzed and confirmed using GC chromatography.

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Two b-N-acetylhexosaminidases (F11 e F15) were purified from Echinometra lucunter gonads extracts. The purified enzymes were obtained using ammonium sulfate fractionation, followed by gel filtration chromatographies (Sephacryl S-200, Sephadex G-75 and Sephacryl S-200). The F11 fraction was purified 192.47 -fold with a 28.5% yield, and F15 fraction 85.41 -fold with a 32.3% yield. The molecular weights of the fractions were 116 kDa for F11 and 42 kDa for F15 using SDS-PAGE. In Sephacryl S-200, F15 was 84 kDa, indicating that it is a dimeric protein. When p-nitrophenyl-β-D-glycosaminide was used as substrate, we determined an apparent Km of 0.257 mM and Vmax of 0.704 for F11 and for F15 the Km was 0.235 mM and Vmax of 0.9 mM of product liberated by hour. Both enzymes have optimum pH and temperature respectively at 5.0 and 45 °C. The enzymes showed inhibition by silver nitrate, while the glucuronic acid was a potent activator. The high inhibition of F15 by N-etylmaleimide indicates that sulphydril groups are involved in the catalysis of synthetic substrate

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En el campo bibliotecológico para desarrollar instrumentos de trabajo que nos permitan comunicarnos con las demás unidades y clientes de información, debemos pensar en normalizar nuestros procesos.Normalizar, en el sentido más amplio, significa seguir reglas que hagan un registro uniforme en cualquier lugar del mundo. Esto se logra mediante la aplicación de códigos y normas que han sido aceptadas internacionalmente por los organismos creados para este fin.El valor de la normalización estriba en evitar la duplicación de los esfuerzos de la catalogación en las diferentes unidades de información documental y facilitar el intercambio de datos bibliográficos tan pronto como sea posible. También, cosiste en darle al cliente la posibilidad de localizar la información en un a forma homogénea que obvie las barreras idiomáticas.

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Advances related to information technology are visible and inherent to the management of contemporary organizations, regardless of industrial action. Synchronized with this dynamic, educational institutions are incorporating technological tools that assist its management and academic support to teachers in teaching and interaction with the students. Given that technological innovations are not always taken homogeneously and with the same degree of coverage, remain current and relevant studies on how these technologies are being used in academia. The objective of this research is to identify the usage profile of the functionality of a virtual learning environment related to teaching (undergraduate or postgraduate), demographic variables (age and gender) and institutional (time of admission and academic center of origin.) The methodology applied to the study is descriptive and quantitative. The research is characterized as census, covering all 2152 teachers of undergraduate and graduate students of the Federal University of Rio Grande do Norte, Brazil, who accessed the virtual classes of the Integrated Management of Academic Activities. The study findings revealed that there is a statistically significant difference regarding the use of these tools to teachers who work with undergraduate (49.3%) compared to graduate (6.6%). Regarding gender, women (40.1%) use the system more than men (38.5%). It was also observed that the younger teachers, aged 37 years, are the most active users (42.5%) of the Virtual Class with respect to their elders. For teachers with up to three years time of admission to the UFRN, the pattern of use is more advanced than those with more seniority, as well as the faculty of the Center for Science and Technology are the least likely to use the tools available in relation to other academic centers. It is hoped that with this study managers can direct actions to improve and expand the use of this environment by teachers

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Inorganic pigment comprises a host lattice, which is part of the chromophore component (usually a transition metal cation) and possible components modifiers, which stabilize, add or restate the properties pigments. Among the materials with spinel, ferrites, and the chromite stand out, because they have broad technological importance in the area of materials, applicability, pigments, catalytic hydrogenation, thin film, ceramic tiles, among others. The present work, pigments containing CuFe2O4, CuCr2O4,e CuFeCrO4, were synthesized by a method that makes use of gelatin as organic precursor using their application to ceramic pigments. The pigments were characterized by X-ray diffraction (XRD), Infrared spectroscopy, scanning electron microscopy (SEM) spectroscopy in the UV-visible and Colorimetry. The results confirmed the feasibility of the synthetic route used, with respect to powders synthesized, there is the formation of spinel phase from 500°C, with an increase in crystallinity and the formation of other phases. The pigments were shown to be crystalline and the desired phases were obtained. The copper chromite have hues ranging from green to black according to the calcination temperature, while the copper chromite doped with iron had brownish. The ferrites showed copper color and darker brown to black, which may indicate an interesting factor because of the importance of black pigment

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Given the environmental concern over global warming that occurs mainly by emission of CO2 from the combustion of petroleum, coal and natural gas research focused on alternative and clean energy generation has been intensified. Among these, the highlight the solid oxide fuel cell intermediate temperature (IT-SOFC). For application as electrolyte of the devices doped based CeO2 with rare earth ions (TR+ 3) have been quite promising because they have good ionic conductivity and operate at relatively low temperatures (500-800 ° C). In this work, studied the Ce1-xEuxO2-δ (x = 0,1, 0,2 and 0,3), solid solutions synthesized by the polymeric precursor method to be used as solid electrolyte. It was also studied the processing steps of these powders (milling, compaction and two step sintering) in order to obtain dense sintered pellets with reduced grain size and homogeneous microstructure. For this, the powders were characterized by thermal analysis, X-ray diffraction, particle size distribution and scanning electrons microscopy, since the sintered samples were characterized by dilatometry, scanning electrons microscopy, density and grain size measurements. By x-ray diffraction, it was verified the formation of the solid solution for all compositions. Crystallites in the nanometric scale were found for both sintering routes but the two step sintering presented significant reduction in the average grain size

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In this work, was studied the formation of a composite of the refractory metal niobium with copper, through the process of high-energy milling and liquid phase sintering. The HEM can be used to synthesize composite powders with high homogeneity and fine size particle distribution. It may also produce the solid solubility in immiscible systems such as Nb-Cu, or extend the solubility of systems with limited solubility. Therefore, in the immiscible system Cu-Nb, the high-energy milling was successfully used to obtain the composite powder particles. Initially, the formation of composite particles during the HEM and the effect of preparation technique on the microstructure of the material was evaluated. Four loads of Nb and Cu powders containing 20%wt Cu were synthesized by MAE in a planetary type ball mill under different periods of grinding. The influence of grinding time on the metal particles is evaluated during the process by the withdrawal of samples at intermediate times of milling. After compaction under different forces, the samples were sintered in a vacuum furnace. The liquid phase sintering of these samples prepared by HEM produced a homogeneous and fine grained. The composite particles forming the sintered samples are the addition of a hard phase (Nb) with a high melting point, and a ductile phase (Cu) with low melting point and high thermal and electrical conductivities. Based on these properties, the Nb-Cu system is a potential material for many applications, such as electrical contacts, welding electrodes, coils for generating high magnetic fields, heat sinks and microwave absorbers, which are coupled to electronic devices. The characterization techniques used in this study, were laser granulometry, used to evaluate the homogeneity and particle size, and the X-ray diffraction, in the phase identification and to analyze the crystalline structure of the powders during milling. The morphology and dispersion of the phases in the composite powder particles, as well the microstructures of the sintered samples, were observed by scanning electron microscopy (SEM). Subsequently, the sintered samples are evaluated for density and densification. And finally, they were characterized by techniques of measuring the electrical conductivity and microhardness, whose properties are analyzed as a function of the parameters for obtaining the composite

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En la presente Tesis Doctoral se abarcan dos objetos de estudio principales y complementarios. El primero es de carácter individual: la vida del brigadier de la Real Armada Juan Gutiérrez de la Concha (1760-1810); mientras que el segundo es colectivo, y se refiere al papel de los marinos destinados en el Virreinato del Río de la Plata entre 1808 y 1814. Ese segundo eje de investigación está además conformado por diversos actores que en realidad se encuentran íntimamente relacionados. La investigación aborda desde una metodología biográfica, basada en la prosopografía, el análisis de la vida y trayectoria profesional de Gutiérrez de la Concha hasta su muerte por oponerse a la Junta revolucionaria de Buenos Aires (mayo de 1810), estudiando las páginas de la historia naval española de las que formó parte. El propósito ha sido entender su trayectoria vital como respuesta a un tiempo cultural (Ilustración – siglo XVIII), a un espacio geo-histórico preciso (España – Virreinato del Río de la Plata), a una formación específica (oficial naval), y a las características particulares que toda persona posee. Las fuentes documentales analizadas han sido numerosas, y tanto su procedencia como su tipología revisten una considerable variedad, encontrándose tanto en archivos españoles como en archivos americanos. Una diversidad que recoge aquella documentación directamente relacionada con la vida y profesión del personaje (acta de bautismo, partida de casamiento, hoja de servicios, expediente militar, memoria testamentaria…), hasta las fuentes de procedencia diversa que nos acercan igualmente a su conocimiento y al de la trayectoria profesional de sus camaradas (memorias de contemporáneos, correspondencia privada, documentos diversos, informes, memoriales, gacetas, correspondencia administrativa…) En los tiempos de la revolución rioplatense los marinos españoles tomaron en su mayoría el partido de oponerse a la misma, aunque no fue una actitud desarrollada de manera monolítica ni homogénea...

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Las políticas de salud destinadas a las mulheres de la comunidad quilombola de Boa Vista son, de manera general, las mismas políticas destinadas al resto de las mujeres de la región rural del Seridó norterriograndense y también las que se corresponden con regiones marginales del Brasil entero. Aquí, el cuerpo femenino es concebido bajo parámetros universalizantes que lo toman como una entidad homogénea y comparable con otros cuerpos femeninos a partir de su traducción en índices, tasas y estadísticas. En este sentido, decimos que son cuerpos desnudos, cuya intervención no considera los rasgos exteriores, aquellos llamados de culturales, como marcadores de identidad. Por otro lado, la noción de Salud de la Mujer Negra propuesta por recientes políticas de Estado a nivel nacional, se muestra inexistente en la comunidad. El cuerpo que se se exalta hoy a partir de los parámetros de reivindicación étnica es un cuerpo negro, pero también bello, jovem e sobre todo, fuerte; donde la noción de salud no penetra. De esta forma, las dos políticas conciben sujetos sociales diferentes. Sin embargo, existe otro espacio, que es el espacio de las prácticas vernáculas, en el que las mujeres experimentan la articulación entre feminilidad y negritud, pero a partir de otros parámetros local e históricamente delineados. Aquí, tanto las trayectorias de las mujeres como las redes de parentesco y cuidado locales se muestran especialmente significativas, ayudando a comprender las concepciones particulares sobre el cuerpo que imaginan y practican las mujeres de esta comunidad, y revelando la importancia de la maternidad como principio ordenador de identidades sociales. Para eso, hemos realizado un trabajo de observación participante, una serie de 30 entrevista com mujeres de Boa Vista y un estudio de las redes de parentesco organizadas alrededor del término mãe. Con esto, demostramos que existe un espacio cargado de significados sobre el cuerpo femenino y la feminilidad que es construido a partir de una interpretación local de la triple condición de mulher, de mãe y de negra

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Dissertação de Mestrado apresentada ao Instituto Superior de Psicologia Aplicada para obtenção de grau de Mestre na especialidade de Psicologia Educacional.

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The mesoporous molecular sieves of the MCM-41 and FeMCM-41 type are considered promissory as support for metals used as catalysts in oil-based materials refine processes and as adsorbents for environmental protection proposes. In this work MCM-41 and FeMCM41 were synthesized using rice husk ash - RHA as alternative to the conventional silica source. Hydrothermal synthesis was the method chosen to prepare the materials. Pre-defined synthesis parameters were 100°C for 168 hours, later the precursor was calcinated at 550°C for 2 hours under nitrogen and air flow. The sieves containing different proportions of iron were produced by two routes: introduction of iron salt direct synthesis; and a modification post synthesis consisting in iron salt 1 % and 5% impregnation in the material followed by thermal decomposition. The molecular sieves were characterized by X ray diffraction XRD, Fourier transform infrared spectroscopy FT-IR, X ray fluorescence spectroscopy XFR, scanning electronic microscopy SEM, specific surface area using the BET method, Termogravimetry TG. The kinetic model of Flynn Wall was used with the aim of determining the apparent activation energy of the surfactant remove (CTMABr) in the MCM- 41 porous. The analysis made possible the morphology characterization, identifying the presence of hexagonal structure typical for mesoporous materials, as well as observation of the MCM41 and iron of characteristic bands.

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The mixed metal oxides constitute an important class of catalytic materials widely investigated in different fields of applications. Studies of rare earth nickelates have been carried by several researchers in order to investigate the structural stability afforded by oxide formed and the existence of catalytic properties at room temperature. So, this study aims synthesize the nanosized catalyst of nickelate of lanthanum doped with strontium (La(1-x)SrxNiO4-d; x = 0,2 and 0,3), through the Pechini method and your characterization for subsequent application in the desulfurization of thiophene reaction. The precursor solutions were calcined at 300ºC/2h for pyrolysis of polyester and later calcinations occurred at temperatures of 500 - 1000°C. The resulting powders were characterized by thermogravimetric analysis (TG / DTG), surface area for adsorption of N2 by BET method, X-ray diffraction (XRD), scanning electron microscopy (HR_SEM) and spectrometry dispersive energy (EDS). The results of XRD had show that the perovskites obtained consist of two phases (LSN and NiO) and from 700ºC have crystalline structure. The results of SEM evidenced the obtainment of nanometric powders. The results of BET show that the powders have surface area within the range used in catalysis (5-50m2/g). The characterization of active sites was performed by reaction of desulfurization of thiophene at room temperature and 200ºC, the relation F/W equal to 0,7 mol h-1mcat -1. The products of the reaction were separated by gas chromatography and identified by the selective detection PFPD sulfur. All samples had presented conversion above 95%

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Este trabajo representa un esfuerzo conjunto llevado a cabo con la principal finalidad, de exponer formalmente algunas de las aplicaciones de la teoría de los valores y vectores propios. La importancia creciente del álgebra lineal como instrumento para poder abordar el estudio de otras disciplinas, es un hecho irrefutable en la actualidad. Propiamente, el uso de la teoría de los valores y vectores propios conduce a resolver importantes problemas en varias ciencias. El rol que desempeña esta teoría transciende su uso fundamental para diagonalizar una matriz a interpretaciones concretas, como ejemplo, el signo de un valor propio nos concede una información relevante en diversos contextos, tales como en teoría de sistemas dinámicos lineales invariantes en el tiempo. Este artículo aborda la aplicación, de los valores y vectores propios para resolver una sucesión definida por una relación de recurrencia homogénea lineal con coeficientes constantes.