1000 resultados para Correntes alternadas


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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Current paper discusses manifestations of the sublime in Pedro Kilkerry´s poetry as one of the distinguishing characteristics within the Parnassian orientations predominant in his cultural context. The particular way that Kilkerry employs the sublime´s expedients demonstrates the dialogue of his poetry with Romantic ideals, whose traits in his lyrical stance are directly linked to Symbolist influence, far from traditional Parnassian models. The sublime in Kilkerry develops through an elliptical and suggestive language that demonstrates the impossibility of the ideal being directly expressed and shows the affinity of his poetic work with the idealist crisis that marks post-Romantic poetry and provides the basis on which the poetics of Modernity is structured. The poetry of Pedro Kilkerry develops within a complex zone of convergence between the models provided by the Parnassian aesthetic, Romantic idealism with an atavic presence to Symbolism, and the search for new answers to old idealistic concerns. The meeting of these three conflictive currents, perceptible in the manifestations of the sublime in Pedro Kilkerry´s poetry, demonstrates his lyrical sensitivity to the trends of Modernity.

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The question of the relationship between subject and object has been discussed and explored in several theoretical and methodological systems, showing resonances and disagreements about the possibilities of developing a science or a philosophical system to allow the construction of the knowledge about the world. Among these, the systems of two authors in particular are different, respectively, regarding the complexity and ontological taxonomic: Michel Foucault and Karl Marx. This work aims to discuss the objectivity and subjectivity in the work of these two thinkers, indicating some possible correlations. The discussions were about the concept of knowledge in Michel Foucault, difficulties experienced by its researchers to classify their work within a classical theoretical system and the difference of Marxist theory in relation to other research programs for not presenting the individual as the fundamental ontological entity. Foucault´s work influenced the process of restoration and redemption of Marxism by Marxists groups.

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The Frankfurt critical theory and the French post-structuralism are important lines of thought in the philosophy of education, which inspired several academic productions in recent decades. In the 1950s and 1960s, both opposed philosophical resistance against many types of totalitarianism. One big difference between the two lines of thought has been the critical of the dialectic considered an insufficient method to think about the difference (Deleuze) and the reaffirmation of a negative dialectic (Adorno). This article intends to analyze the thematic affinities and the differences of method between the thought of these two authors.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Biologia Geral e Aplicada - IBB

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The development of electrocatalysts for the oxidation of methanol and ethanol is very important, because these alcohols may be used in the anode fuel cells which convert chemical energy directly into electrical energy with high efficiency, cleanly and with low noise. Thus, this study reports to the synthesis of nanocatalysts of PtAu supported on carbon by microemulsion method. The physical characterization of these catalysts is performed through the techniques of X-ray diffraction and transmission electron microscopy. The catalytic activity of the prepared materials was studied using conventional electrochemical techniques and also the technique of spectro-electrochemical in situ FTIR, which allows identification of intermediates and products of the reactions. From the x-ray diffraction, it was observed that the thermal treatment applied to catalysts favored incorporation of Au into the crystal lattice of Pt,that is, increased the formation of PtAu alloy. Micrographs indicated particle size about 3 nm to materials not heat treated and 9 nm to materials subjected to thermal treatment (heating at 150 ° C for 1h and 30 min in argon atmosphere). Current density oxidation of methanol on PtAu / C were superior to pure platinum. Spectroscopic results indicated the presence of formate in solution in 50:50 and the composition showed bands for CO2, indicating complete oxidation, in lower potential. During ethanol oxidation on the catalyst PtAu, the main product formed was acetate, product of incomplete oxidation. The good performance for methanol oxidation can be attributed to large amounts of oxygen species adsorbed on the catalyst surface, or an electronic effect.

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Once petroleum is na exhaustible source of energy, alternative fuels are having more prominence. A much discussed option for replacing fossil fuels is the use of biofuels derived from oils or fats, especially biodiesel. The biodiesel preparation is through a reaction named transesterification, a reaction of triglycerides with a short chain alcohol with a catalyst, producing a mixture of fatty acid esters and glycerol. According to ANP (National Petroleum Agency) specifications, biodiesel can have contaminants due to the catalyst or oil used on its synthesis, such as phosphorus, wich can damage the catalytic converter and cause significant increase in the particles emission. This project aims to develop na alternative method using chemically modified electrodes with iron nanoparticles for determination of phosphorus in biodiesel. For the formation of the iron nanoparticles film on the surface of a glassy carbon electrode, was used a iron sulfate solution. The film was formed after 10 successive cycles, with a scanning speed of 50 mV s-1 and a potential range of -0,9 to -1,25 V. To reduce possible oxides on the surface and activate the electrode, it has been subjected to a cathodic polarization with a potential of -1,25 V for 15 minutes in a sodium hydroxide solution. In cyclic voltammograms obtained in the study of the speed of scanning, there is an increase in the intensity of the anodic and cathodic current peaks. The cathodic peak current varied linearly with the square root of scan rate, showing that the electrode is controlled by diffusion. After successive additions of phosphate there is a linear variation in the current peak in the concentration range of 1,0 x 10-7 a 1,0 x 10-6 mol L-1. To determine if the concentration of phosphorus in real sample, the method of adding standard was used by adding aliquots of phosphate ions in the solution containing soy biodiesel extracted with ....

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Pós-graduação em Ciência e Tecnologia de Materiais - FC

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Pós-graduação em Economia - FCLAR

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Pós-graduação em Ciência e Tecnologia de Materiais - FC

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We interviewed 21 farmers in order to access which sanitary practices adopted in the production systems of beef cattle on farms located in São Paulo, Mato Grosso, Mato Grosso do Sul and Rondonia. The survey was conducted through a qualitative approach to the collection of data obtained through questionnaire and personal interview with the landowners. We questioned the attitudes and sanitation procedures in these current production systems such as veterinary assistance, preventive health practices and disease surveillance, knowledge of health hazards for the safe production of food, animal feed, vaccine and immunizations, registration system, measures with newborns, products used in the environment and animals, grace period, employee training, destination of the dead animals, among others. Along with the data found that only 30% of properties had veterinary care, 67% said they meet the expiration dates of the products, although it was not mentioned on the products if there were any. In only 48% of properties were veterinarians who prescribed drugs to animals. Only two of the owners confirmed buying and using expired products in animals and only 48% have received some training on the property. In this setting, it is evident that farmers should be better prepared for insertion of its products in a highly demanding and competitive market. In this context, add value to the product depends mainly on the condition of sanitation of the herds.