40 resultados para Cromatografía del gas


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Debido a preocupaciones ambientales y de abastecimiento de energía, se buscan alternativas renovables al petróleo. En 2004, fue lanzado, en Brasil, el Programa Nacional de Producción y Uso de Biodiésel con el objetivo de sustituir el diesel y fomentar la inclusión social de los agricultores familiares, especialmente de las regiones más pobres. El biodiésel representaría así una nueva fuente de renta y de desarrollo sostenible para las zonas productoras de oleaginosas. A partir del estudio realizado en la región Semiárida del Estado de Ceará, se observó que la baja remuneración de la producción agrícola y el reducido número de empleos generados hacen del mercado del biodiésel un suplemento de la renta familiar. Ambientalmente, la durabilidad se ve comprometida por el problema endémico de la sequía – agravado por el cambio climático – y las prácticas agrícolas tradicionales. Parece igualmente necesario fomentar los cultivos cuya producción, tradición cultural y uso potencial sean compatibles con la lógica de la agricultura familiar. En definitiva, el programa, a través del Sello Combustible Social, representaría un componente de una matriz de políticas para el desarrollo rural sostenible de la agricultura familiar, entre las cuales estarían la adaptación del sistema productivo y de apoyo y acceso a la tierra.

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Pine forests constitute some of the most important renewable resources supplying timber, paper and chemical industries, among other functions. Characterization of the volatiles emitted by different Pinus species has proven to be an important tool to decode the process of host tree selection by herbivore insects, some of which cause serious economic damage to pines. Variations in the relative composition of the bouquet of semiochemicals are responsible for the outcome of different biological processes, such as mate finding, egg-laying site recognition and host selection. The volatiles present in phloem samples of four pine species, P. halepensis, P. sylvestris, P. pinaster and P. pinea, were identified and characterized with the aim of finding possible host-plant attractants for native pests, such as the bark beetle Tomicus piniperda. The volatile compounds emitted by phloem samples of pines were extracted by headspace solid-phase micro extraction, using a 2 cm 50/30 mm divinylbenzene/carboxen/polydimethylsiloxane table flex solid-phase microextraction fiber and its contents analyzed by high-resolution gas chromatography, using flame ionization and a non polar and chiral column phases. The components of the volatile fraction emitted by the phloem samples were identified by mass spectrometry using time-of-flight and quadrupole mass analyzers. The estimated relative composition was used to perform a discriminant analysis among pine species, by means of cluster and principal component analysis. It can be concluded that it is possible to discriminate pine species based on the monoterpenes emissions of phloem samples.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro

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Erosion surfaces are the main geomorphological features of the Hesperian Massif. However, three other physiographic elements define the present state of the landscape. Such are big mountain blocks with polygonal borders building at great scale mountain chains, some more modest ridges following hercynian structural trends, and finally the strong incision of the fluvial net. On the other hand, paleoalterations and associated sediments are the only available ways for relief correlation and interpretation. It consists of a triple relationship giving good results when the regional stratigraphy is well known. Tectonic massifs, differential relief sand incisions are originated by geotectonic alpine disturbances during the Tertiary. The three events are consecutive in time with overlapping lapses which the prior and following element: differencial reliefs as a mesozoic heritage occur first, afterwards morphostructural blocks responding directly to the alpine deformation, and finally the fluvial incision as a delayed answer to the preceding morphostructural changes. The relationship relief sedimentation confirms widely this idea, since an association exists between a siderolitic Cretaceous-lower Paleogene and the differential reliefs, between arkoses from the upper Paleogene and the tectonic morphostructural blocks and between the Neogene Series Ocres and the terraces.

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Based upon the depositional sequences in the Guadalquivir basin and the bio-events defined (foraminifera and nanoplancton) we present the synthesis of the paleontological results in correlation with the Neogene of Algarve (Portugal). We present the most representative outcrops for micropaleonlologic results, as well as paleoenvironmental correlations between Algarve and the Guadalquivir basin.

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A sequência estratigráfica cenozóica da bacia do Guadiana entre Mérida e Badajoz está representada por depósitos de leque aluvial e fluviais. Neste trabalho apresenta-se urna primeira descrição de duas das unidades de preenchimento da bacia. A primeira corresponde a sedimentos de idade miocénica que se encaixaram nos depósitos de Ieque aluvial, que os antecedem, desenvolvendo um sistema fluvial com urna direcção principal E-W, caracterizado pela presença de barras e canais arenosos associados a níveis edáficos, com fraco desenvolvimento da planície de inundação. A segunda unidade, de idade pliocénica, representa a instalação de uma nova rede de drenagem que se sobrepõe e erode os sedimentos miocénicos. A direcção principal entre Mérida e Badajoz continua a ser E-W, para inflectir para o S em Badajoz. As facies pliocénlcas são essencialmente conglomeráticas e arenosas, correspondendo a canais móveis e barras formadas em consequência de processos de migração e encaixe da rede fluvial. Ambos os sistemas fluviais representam parte da evolução do preenchimento da bacia do Guadiana desde o Miocénico até ao Plio-Quaternário, sendo as principais diferenças entre ambos interpretadas como devidas a modificações tectónicas pre-quaternárias na região.

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41º Congresso Internacional de História da Medicina (Societé Internationale d´Histoire de la Médecine), México, 2008

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RESUMO - El autor aborda algunos aspectos relativos a la Salud y Seguridad del Trabajo (SST) en Portugal llamando la atención para, esencialmente, intentar sostener la tesis de que, desde mediados de la década de los 90, se observaron importantes avances en la mejoría de las condiciones del trabajo en la perspectiva de la SST, aunque se mantuvieron algunos problemas en la práctica concreta de las normativas legales. Incluso con estas mejoras, las tasas de frecuencia de accidentes de trabajo y de enfermedades profesionales en Portugal todavía se mantienen muy elevadas necesitando, por tanto, estrategias más “agresivas” para concienciar la sociedad portuguesa en torno a las políticas públicas de SST efectivamente promotoras de prevención de riesgos profesionales y de la promoción de la salud de quien trabaja. Es por tanto indispensable que la protección de la salud y de la seguridad de los trabajadores en los puestos de trabajo sea encarada como un conjunto de actividades de indiscutible utilidad para todos los representantes del mundo del trabajo e que la agenda política pase a valorizar, aún más, la promoción de espacios de trabajo saludables y seguros, con la consecuente valorización de las variables individuales en la estrategia nacional de salud y seguridad.--------------------------ABSTRACT – In the present work, the author analyzes several aspects of Occupational Health and Safety (OHS) in Portugal. He provides evidence sustaining the assumption of an important progress, since the mid-nineties, in the improvement of the working conditions from an OHS perspective. Nevertheless, several problems still remain in the practical application of legal regulations. In addition, despite of these improvements, the frequency rates of working accidents and occupational diseases remain very high. Hence, more “aggressive” strategies are required to increase the awareness of the Portuguese society relative to the OHS public policies, whose effectiveness has been demonstrated either in terms of occupational risks prevention and workers health promotion. The protection of workers’ health and safety at the workplace must then be assumed as an activity of indisputable utility by all stakeholders. The political agenda must thus promote even more the promotion of healthy and safe workplaces. As a consequence, there would be also a higher development of individual aspects, and not only environmental data, in the national strategy of occ

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Dissertação apresentada para obtenção do Grau de Doutor em Ciências do Ambiente pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecn

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pp. 9-30

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Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica

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Dissertation to obtain the Master Degree in Biotechnology

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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente Perfil Gestão de Sistemas Ambientais

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics