880 resultados para transferência de massa


Relevância:

20.00% 20.00%

Publicador:

Resumo:

O agronegócio, setor imponente da economia no Brasil, é um dos responsáveis por parte significativa da produção de alimentos. Neste sentido, o setor necessita de um constante aprimoramento e de um vasto investimento em pesquisas e inovações. Para que a tecnologia desenvolvida nos centros de pesquisas chegue até a lavoura, ela precisa passar por muitos estágios. Em alguns destes estágios, os responsáveis pela utilização da tecnologia podem ser pessoas leigas, como pequenos produtores rurais. Assim a transferência de tecnologia e conhecimento são fatores determinantes para disseminação das inovações no agronegócio brasileiro. Portanto, esta dissertação tem o objetivo de identificar as práticas de difusão de tecnologia no agronegócio do médio norte Mato-Grossense. Trata-se de um estudo descritivo com abordagem quantitativa. A pesquisa foi realizada nas cidades de Sorriso e Vera, ambas no médio norte mato-grossense. Os dados foram coletados por meio de questionários estruturados direcionados aos pequenos produtores rurais e profissionais do agronegócio da região. Participaram da pesquisa 109 pequenos produtores rurais e 106 profissionais do agronegócio. Os resultados desta pesquisa demonstram que existe um alinhamento entre os produtos inovadores adquiridos pelos pequenos produtores rurais e os produtos inovadores ofertados pelos profissionais. A pesquisa também revelou que os produtores na sua maioria adquirem produtos inovadores com o objetivo de aumentar a produtividade. Observou-se que os profissionais na sua grande maioria trabalham com Commodities, e os últimos produtos inovadores que eles prestaram assistência técnica foram as sementes de soja do tipo intacta. O que demonstrou um alinhamento entre o que é ofertado pelos profissionais e o que é adquirido pelos pequenos produtores rurais. Cabe destacar também as contribuições deste estudo para a região, visto que existe a necessidade de estratégias que promovam um melhor aproveitamento das unidades de terra, assim como uma maior inserção dos pequenos produtores rurais nas unidades de demonstração e uma maior participação destes produtores em experimentos agrícolas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

VARELA, M. L. et al. Influência da adição de resíduo de caulim nas propriedades tecnológicas de uma massa padrão de porcelanato produzido em escala industrial. Cerâmica, v.55, n.334 p.209-215. 2009.ISSN 0366-6913.Disponível em: . Acesso em: 06 out. 2010.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

MAIA, Maria Aniolly Queiroz et al. O bibliotecário como mediador no processo de transferência da informação para pessoas com deficiência visual. In: CONGRESSO BRASILEIRO DE BIBLIOTECONOMIA, 24., DOCUMENTAÇÃO E CIÊNCIA DA INFORMAÇÃO, 2011, Maceió. Anais... Maceió: CBBD, 2011

Relevância:

20.00% 20.00%

Publicador:

Resumo:

O presente trabalho tem como principal objectivo a avaliação do sujamento da superfície de transferência de calor do evaporador de uma bomba de calor, quando se utiliza o efluente da fábrica de pasta e papel da Portucel Soporcel em Cacia como fluido de aquecimento. Para a realização deste estudo montou-se uma instalação, composta por uma bomba de calor, um circuito de água de arrefecimento do condensador da bomba de calor e um circuito de água residual quente para o aquecimento do evaporador da bomba de calor. O ensaio decorreu durante um período de 84 dias, durante o qual foram registadas as temperaturas em vários pontos dos circuitos e os caudais de circulação. A evolução temporal da quantidade de calor transferida no evaporador, assim como, a comparação do coeficiente global de transferência de calor em condições ideias e experimentais, permitiu verificar que a razão U/U0 para o evaporador da bomba de calor não teve um comportamento decrescente ao longo do período de ensaio, permitindo concluir que, nas condições operatórias da experiência, não ocorreu sujamento na superfície do evaporador. No estudo de corrosão do cobre quando exposto à água residual em questão, obteve-se, para a velocidade de corrosão, o valor de 1,56 mg/(dm2 .dia), indicando assim que a corrosão do cobre naquele meio é praticamente inexistente.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Com a crescente internacionalização da economia e a expansão dos grupos económicos à escala internacional, os Estados foram obrigados a rever os seus sistemas fiscais no sentido de combater o risco de manipulação dos preços de transferência e de reforçar os seus mecanismos de controlo sobre as entidades relacionadas...

Relevância:

20.00% 20.00%

Publicador:

Resumo:

O stress oxidativo está associado ao envelhecimento e a inúmeras patologias, nomeadamente a doenças neurodegenerativas e cardiovasculares, e a diversos outros fatores. O stress oxidativo leva à oxidação de importantes biomoléculas como os lípidos e, ao contrário da maior parte dos produtos de oxidação de fosfolípidos e ácidos gordos insaturados (PUFAS), os produtos de oxidação de glicosfingolípidos (GSLs) têm sido escassamente estudados. Os glicosfingolípidos são moléculas muito diversificadas estruturalmente e com importantes funções, essencialmente no sistema nervoso central (SNC) onde estão localizados maioritariamente. Deste modo, alterações na estrutura dos GSLs conduzirão a consequente comprometimento das suas funções e ao possível desenvolvimento de patologias. Assim para identificar as modificações oxidativas que ocorrem em glicosfingolípidos e pressupor consequentes efeitos biológicos nas células sob stress oxidativo, prepararamse sistemas modelo biomiméticos com diferentes GSLs os quais foram expostos a radicais hidroxilo gerados sob condições da reação de Fenton (H2O2 e Fe2+) e as reações foram monitorizadas por diferentes metodologia utilizando a espectrometria de massa. Os resultados obtidos com este estudo permitiram-nos identificar vários produtos de oxidação produzidos durante a oxidação desta classe de lípidos. Os produtos de oxidação observados em comum, em todos os GSLs estudados (C16:0GalCer, C24:1GalCer, C24:1LacCer e GM1) foram as suas correspondentes ceramidas. Estas atuam como agentes pro-apoptóticos e podem in vivo promover a neurodegeneração nas células sob stress oxidativo. Também foi possível observar produtos com inserção de oxigénio junto às duplas ligações ou na cadeia de esfingosina (no caso do GM1) ou na cadeia de ácido gordo monoinsaturada (no caso da C24:1GalCer, C24:1LacCer), corroborando o facto de que ácidos gordos saturados não são susceptíveis à oxidação por radicais. Interessantemente em ambos os GSLs de cadeias glicosiladas compostas com mais de um açúcar (C24:1LacCer e GM1) observou-se a despolimerização oxidativa da porção glicosilada por quebra das correspondentes ligações glicosídicas. Esta degradação leva à formação de GlcCer no caso de oxidação de LacCer ou na formação de outros gangliósidos (GM2, GM3, asialoGM1 e asialoGM2) e glicolípidos (LacCer e GlcCer), no caso de oxidação de GM1. A formação por via radicalar não enzimática destes GSLs leva a distúrbios no perfil lipídico. Previamente, em certas doenças, foram observadas variações na concentração do perfil de gangliósidos e de ceramidas. Estes dados permitem sugerir que em células em condições de stress oxidativo, a acumulação de gangliósidos mais simples e ceramidas poderá ter uma contribuição de produtos da degradação oxidativa dos gangliósidos e GSLs mais complexos. Este trabalho contribui assim para uma melhor compreensão das modificações estruturais que ocorrem em alguns glicosfingolípidos em condições de stress oxidativo. Os produtos de oxidação aqui identificados suportam a sua possível futura deteção em sistemas biológicos.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Brazilian agricultural research agency has, over the years, contributed to solve social problems and to promote new knowledge, incorporating new advances and seeking technological independence of the country, through the transfer of knowledge and technology generated. However, the process of transfering of knowledge and technology has represented a big challenge for public institutions. The Embrapa is the largest and main brazilian agricultural research company, with a staff of 9.790 employees, being 2.440 researchers and an annual budget of R$ 2.52 billion. Operates through 46 decentralized research units, and coordinate of the National Agricultural Research System - SNPA. Considering that technology transfer is the consecration of effort and resources spent for the generation of knowledge and the validity of the research, this work aims to conduct an assessment of the performance of Embrapa Swine and Poultry along the production chain of broilers and propose a technology transfer model for this chain, which can be used by the Public Institutions Research – IPPs. This study is justified by the importance of agricultural research for the country, and the importance of the institution addressed. The methodology used was the case study with a qualitative approach, documentary and bibliographic research and interviews with use of semi-structured questionnaires. The survey was conducted in three stages. In the first stage, there was a diagnosis of the Technology Transfer Process (TT), the contribution of the Embrapa Swine and poultry for the supply chain for broiler. At this stage it was used bibliographical and documentary research and semi- structured interviews with agroindustrial broiler agents, researchers at Embrapa Swine and Poultry, professionals of technology transfer, from the Embrapa and Embrapa Swine and Poultry, managers of technology transfer and researchers from the Agricultural Research Service - ARS. In the second step, a model was developed for the technology transferring poultry process of Embrapa. In this phase, there were made documentary and bibliographic research and analysis of information obtained in the interviews. The third phase was to validate the proposed model in the various sectors of the broilers productive chain. The data show that, although the Embrapa Swine and Poultry develops technologies for broiler production chain, the rate of adoption of these technologies by the chain is very low. It was also diagnosed that there is a gap between the institution and the various links of the chain. It was proposed an observatory mechanism to approximate Embrapa Swine and Poultry and the agents of the broiler chain for identifying and discussing research priorities. The proposed model seeks to improve the interaction between the institution and the chain, in order to identify the chain real research demands and the search and the joint development of solutions for these demands. The proposed TT model was approved by a large majority (96.77%) of the interviewed agents who work in the various links in the chain, as well as by representatives (92%) of the entities linked to this chain. The acceptance of the proposed model demonstrates the willingness of the chain to approach Embrapa Swine and Poultry, and to seek joint solutions to existing problems.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Among the toxic elements, Cd has received considerable attention in view of its association with a number of human health problems. The objectives of this study were to evaluate the Cd availability and accumulation in soil, transfer rate and toxicity in lettuce and rice plants grown in a Cd-contaminated Typic Hapludox. Two simultaneous greenhouse experiments with lettuce and rice test plants were conducted in a randomized complete block design with four replications. The treatments consisted of four Cd rates (CdCl2), 0.0; 1.3; 3.0 and 6.0 mg kg(-1), based on the guidelines recommended by the Environmental Agency of the State of São Paulo, Brazil (Cetesb). Higher Cd rates increased extractable Cd (using Mehlich-3, Mehlich-1 and DTPA chemical extractants) and decreased lettuce and rice dry matter yields. However, no visual toxicity symptoms were observed in plants. Mehlich-1, Mehlich-3 and DTPA extractants were effective in predicting soil Cd availability as well as the Cd concentration and accumulation in plant parts. Cadmium concentration in rice remained below the threshold for human consumption established by Brazilian legislation. on the other hand, lettuce Cd concentration in edible parts exceeded the acceptable limit.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The β-proteobacterium Chromobacterium violaceum is a Gram-negative, free-living, saprophytic and opportunistic pathogen that inhabits tropical and subtropical ecosystems among them, in soil and water of the Amazon. It has great biotechnological potential, and because of this potential, its genome was completely sequenced in 2003. Genome analysis showed that this bacterium has several genes with functions related to the ability to survive under different kinds of environmental stresses. In order to understand the physiological response of C. violaceum under oxidative stress, we applied the tool of shotgun proteomics. Thus, colonies of C. violaceum ATCC 12472 were grown in the presence and absence of 8 mM H2O2 for two hours, total proteins were extracted from bacteria, subjected to SDS-PAGE, stained and hydrolysed. The tryptic peptides generated were subjected to a linear-liquid chromatography (LC) followed by mass spectrometer (LTQ-XL-Orbitrap) to obtain quantitative and qualitative data. A shotgun proteomics allows to compare directly in complex samples, differential expression of proteins and found that in C. Violaceum, 131 proteins are expressed exclusively in the control condition, 177 proteins began to be expressed under oxidative stress and 1175 proteins have expression in both conditions. The results showed that, under the condition of oxidative stress, this bacterium changes its metabolism by increasing the expression of proteins capable of combating oxidative stress and decreasing the expression of proteins related processes bacterial growth and catabolism (transcription, translation, carbon metabolism and fatty acids). A tool with of proteomics as an approach of integrative biology provided an overview of the metabolic pathways involved in the response of C. violaceum to oxidative stress, as well as significantly amplified understanding physiological response to environmental stress. Biochemical and "in silico" assays with the hypothetical ORF CV_0868 found that this is part of an operon. Phylogenetic analysis of superoxide dismutase, protein belonging to the operon also showed that the gene is duplicated in genome of C. violaceum and the second copy was acquired through a horizontal transfer event. Possibly, not only the SOD gene but also all genes comprising this operon were obtained in the same manner. It was concluded that C. violaceum has complex, efficient and versatile mechanisms in oxidative stress response

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The WTP produce many kinds of residue on your treatment stages, but the sludge is the more problematic from the final disposition point view. The actual rate of residue production deriving from technological evolution and the crescent population needs prevents the subtle equilibrium generation between consumption and recycling/reuse, creating problems of pollution resulting from inappropriate management of residues. Thus, is necessary achieve a new equilibrium between the grow from raw materials and energy and the residue generation. This equilibrium should be achieved by technical and economic feasibility of environmental supported models through recycling and reuse. The red ceramic industry stand out in residue absorption question as raw material due their clay mass heterogeneity, constituted by clay minerals and non-clay minerals with wide mineralogical variation, allowing residue inclusion which act like plastic or non-plastic materials, contributing to retain heavy metals contained in residues in the vitreous mass formed during the burning of the ceramic bodies. This work propose the study of the influence of incorporation of 25 wt.% sludge from wastewater treatment plant, according preliminary results, in the mass to produce ceramic bodies. The raw materials was characterized through chemical composition analyses by XRF, mineralogical analyses by XRD, thermal analyses by TG and DTA, Atterberg limits and thermodilatometry. Subsequently was composed the mass with 75 wt.% of clay and 25 wt.% of dried wastewater sludge from UFRN WWTP. Samples with 6,0 x 2,0 x 0,5 cm was produced with unidirectional compacting under pressure of 20MPa and burned in temperatures between 950 and 1,200ºC. After fired, the ceramic bodies have been submitted to physical and mechanical analyses through the measure of firing shrinkage, water absorption, density, apparent porosity and flexural strength; crystallographic analyses through XRD and microstructure analyses by SEM. The technological properties obtained was satisfactory to production of roof tiles with 25 wt.% at 1,200 ºC, but the production of others products at lower temperatures was not feasible

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Piauí state is a major producer of traditional red ceramic burning as bricks, tiles and ceramic tiles, with its main production center located in the city of Teresina. The state has large reserves of raw materials that can be used in the ceramic coating as clays, quartz, talc and carbonates. However, in the preparation of ceramic bodies using only a mixture of clays with different characteristics. The study aims to evaluate the effect of adding two types of carbonates in the ceramic semiporous mass coating produced in Piauí and then to verify the potential use of these carbonates as supplementary raw material product manufactured or the feasibility of obtaining a ceramic plate that meets the specifications for the porous coating. For this, were characterized the ceramic Piauí coating mass, a calcitic carbonate and a dolomitic, were made in the levels of 2, 4, 8, 16, and 32%. The masses were formed by pressing and burneds in two environments: a laboratory furnace (1080°C, 1120°C, 1140°C, and 1160°C) and an industrial furnace (1140°C). Then, following tests of linear shrinkage water absorption, apparent porosity, bulk density and flexural strength. Furthermore, the fired specimens were tested for their macrostructure and microstructure. The results showed the possibility of using the carbonate in ceramic mass flooring produced in Piauí, as added in small proportions improved dimensional stability and increased mechanical strength of ceramics pieces. It also proved itself possible to produce porous coating when added in higher levels

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Dissertação de Mestrado Integrado em Medicina Veterinária

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Over recent years the structural ceramics industry in Brazil has found a very favorable market for growth. However, difficulties related to productivity and product quality are partially inhibiting this possible growth. An alternative for trying to solve these problems and, thus, provide the pottery industry the feasibility of full development, is the substitution of firewood used in the burning process by natural gas. In order to contribute to this process of technological innovation, this paper studies the effect of co-use of ceramic phyllite and kaolin waste on the properties of a clay matrix, verifying the possible benefits that these raw materials can give to the final product, as well as the possibility of such materials to reduce the heat load necessary to obtain products with equal or superior quality. The study was divided into two steps: characterization of materials and study of formulations. Two clays, a phyllite and a residue of kaolin were characterized by the following techniques: laser granulometry, plasticity index by Atterberg limits, X-ray fluorescence, X-ray diffraction, mineralogical composition by Rietveld, thermogravimetric and differential thermal analysis. To study the formulations, specifically for evaluation of technological properties of the parts, was performed an experimental model that combined planning involving a mixture of three components (standard mass x phyllite x kaolin waste) and a 23 factorial design with central point associated with thermal processing parameters. The experiment was performed with restricted strip-plot randomization. In total, 13 compositional points were investigated within the following constraints: phyllite ≤ 20% by weight, kaolin waste ≤ 40% by weight, and standard mass ≥ 60% by weight. The thermal parameters were used at the following levels: 750 and 950 °C to the firing temperature, 5 and 15 °C/min at the heating rate, 15 and 45min to the baseline. The results showed that the introduction of phyllite and/or kaolin waste in ceramic body produced a number of benefits in properties of the final product, such as: decreased absorption of water, apparent porosity and linear retraction at burn; besides the increase in apparent specific mass and mechanical properties of parts. The best results were obtained in the compositional points where the sum of the levels of kaolin waste and phyllite was maximal (40% by weight), as well as conditions which were used in firing temperatures of 950 °C. Regarding the prospect of savings in heat energy required to form the desired microstructure, the phyllite and the residue of kaolin, for having small particle sizes and constitutions mineralogical phases with the presence of fluxes, contributed to the optimization of the firing cycle.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, 2016.