455 resultados para híbridos


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Fuel cells powered directly with ethanol (Direct Ethanol Fuel Cell-DEFC) are very attractive for the possibility of using a renewable fuel in the generation of clean energy. However, it is still necessary to deepen the understanding of catalytic processes and their dependence on the catalytic properties. This work proposes to study the catalytic activity of ethanol oxidation in an alkaline medium of Pd nanoparticles supported in carbon oxide hybrids using various transition metal oxides (MoO3, TiO2, WO3 and ZrO2). The materials prepared were characterized by techniques such as X-ray diffraction, transmission electron microscopy (TEM) and X-ray dispersive spectroscopy (EDX) to verify the structure, the distribution of particles in the supports and the presence of Pd on particles oxide. Experiments of X-rays absorption spectroscopy were carried out using soft X-rays (SXS) to evaluate the changes in the electronic properties of the Pd particles caused by interactions with different oxides. Measurements of cyclic voltammetry and potential sweeps of adsorbed CO oxidation allowed evaluating general aspects of the catalysts' electrochemical behavior and determining the electrochemically active area thereof. The catalytic performances of ethanol oxidation in alkaline medium were evaluated by electrochemical techniques (potential scan and chronoamperometry), and showed an improvement in activity with the addition of oxides in material containing only carbon, which was most pronounced for the catalyst containing TiO2. This improvement was predominantly associated with the electronic effects caused by the interaction of Pd on the support, causing a vacancy in the 4d band of Pd which, in turn, produces variations in adsorption energies of the species...

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This paper aims to make a Postcolonial Reading of the Gothic novel Dracula, written by Bram Stoker. Most importantly, it is considered how the subaltern is silenced, and that how this silence reflects the characters responsible for the discourse construction in the book. For this purpose, the theories of three important writers of the Post-Colonialism, Edward Said, Homi Bhabha and Gayatri Chakravorty Spivak, were studied, as well as the enlightening ideas of Stephen Arata in The Occidental Tourist: Dracula and the Anxiety of Reverse Colonization. It also verified the construction of Orientalism in Stoker's work, and its constitutively hybrid and transparent characters due the speech manipulation with the ideological filter of the hegemonic power. This manipulation also characterizes the fragmentation in the work, which is an indication, among others, of modernity in Stoker's novel

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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