963 resultados para fontes de carbono e nitrogênio
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia - FEIS
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Zootecnia - FCAV
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The energy is considered one of the most important elements in the human´s life providing the survival as well as the well being. Nowadays, the technologies destined to generate power burn fossil fuels which pour gases (carbon dioxide among them) that contribute to the global warming phenomenon. Several research groups and universities have been studying different methods for generating power with low carbon dioxide emissions, including the possibility of burning zero-carbon fuels. In this text, it has been put attention to the Advanced Zero Emission Power Plants (AZEP) which separate the CO2 (from the gases involved in the power generation), compress it, dehydrate it and store it in appropriate reservoirs. The goal of this study was to find a possible solution to produce CO from CO2, activated by solar energy; the reaction between CO and steam generates a syngas comprised of H2 and CO2, which can be separated by chemical and/or physical processes. The text also contains a study concerning the compressed air energy storage power plant (CAES) and come up with its modification to C[CO2]ES. This power plant stores CO2 directing it to a reverse combustion process to produce CO which is headed to a syngas reactor to produce CO2 and H2. Hydrogen is separated and carried to the thermal cycle to generate power with low carbon emissions
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A concentração de dióxido de carbono (CO2) global eleva-se a cada ano, isso deve-se a um desequilíbrio entre as taxas de emissão deste gás por atividades antropogênicas e fontes naturais e a taxa que a biosfera e oceanos o removem da atmosfera. O CO2 é um importante constituinte químico do ambiente, pois este é um gás que aprisiona radiação infravermelha emitida pela superfície da Terra, contribuindo, assim, para a manutenção da temperatura global necessária a vida. As alterações na concentração de CO2 na atmosfera afetam inúmeros animais que dependem que estas estejam altamente controladas para poderem sobreviver. Em abelhas Apis mellifera valores elevados de temperatura ou níveis de CO2 dentro da colméia podem ter efeitos deletérios. Estes insetos são considerados bioindicadores naturais, pois apresentam diferenças fisiológicas conforme as condições do ambiente, sendo utilizadas na avaliação de efeitos a várias substâncias presentes no meio. Atualmente uma das técnicas utilizadas para a avaliação do efeito de estímulos externos é a utilização da marcação da proteína c-Fos através da expressão do gene c-fos, que indicam tanto a existência de atividade celular como também possibilita a identificação de áreas cerebrais determinadas. Esta proteína foi utilizada com o intuído de verificar se concentrações elevadas de gás carbônico são capazes de alterar as funções cerebrais da abelha Apis mellifera, comprometendo sua atividade de orientação e, conseqüentemente seu forrageamento. Marcações positivas à proteína Fos foram observadas nas regiões dos lobos ópticos e ocelos tanto do grupo controle quanto dos grupos Resumo Jacob, C. R. O. 9 expostos ao gás dióxido de carbono para todas as idades coletadas, estes resultados estão relacionados com a...(Resumo completo, clicar acesso eletrônico abaixo)
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In this work, plasma immersion ion implantation (PIII) treatments of carbon fibers (CFs) were performed in order to induce modifications of chemical and physical properties of the CF surface aimed to improve the performance of thermoplastic composite. The samples to be treated were immersed in nitrogen or air glow discharge plasma and pulsed at −3.0 kV for 2.0, 5.0, 10.0, and 15.0 min. After PIII processing, the specimens were characterized by atomic force microscopy (AFM), scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). After CFs treatments, the CF/Polypropylene (PP) composites were produced by hot pressing method. Surface morphology of as-received CFs exhibited some scratches aligned along the fibers due to the fiber manufacturing process. After both treatments, these features became deeper, and also, a number of small particles nonuniformly distributed on the fiber surface can be observed. These particles are product of CF surface sputtering during the PIII treatment, which removes the epoxy layer that covers as-received samples. AFM analyses of CF samples treated with nitrogen depicted a large increase of the surface roughness (Rrms value approximately six times higher than that of the untreated sample). The increase of the roughness was also observed for samples treated by air PIII. Raman spectra of all samples presented the characteristic D- and G-bands at approximately 1355 and 1582 cm−1, respectively. Analysis of the surface chemical composition provided by the XPS showed that nitrogen and oxygen were incorporated onto the surface. The polar radicals formed on the surface lead to increasing of the CF surface energy. Both the modification of surface roughness and the surface oxidation contributed for the enhancement of CF adhesion to the polymeric matrix. These features were confirmed ... (Complete abstract click electronic access below)
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Pós-graduação em Zootecnia - FCAV
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This research examines the merits of hallucinogenic plants considered and/or psychoactive substances, such as Cannabis sativa and Ipomoea violacea, using the isotope rates of stable isotope of oxygen (18O) and nitrogen (15N), continuing projects already developed by the research group at the Center for Stable Isotope (CIE), which evaluated the isotopes carbon-13. This paper helps in creating a database that we intent to use in evaluation of each plant merit. Through the IRMS (Isotope-Ratio Mass Spectrometry) technique, it has shown that some of the 24 samples of marijuana (Cannabis sativa L.) evaluated were similar to those grown in the regions of Fairbanks and Tanacross Alaska, USA. In turn, the 50 samples of Ipomoea violacea, coming from Botucatu (SP) and Três Lagoas (MS), got their differences detected, in order to clearly identify the discrepancies between their growing regions. Thus, it was possible not only to track the geographical differences between marijuana samples collected from different regions, but also evaluate the isotopic variation of leaf, flower and seed of Ipomoea violacea. With this database, it was possible to determine the origin region of the drug and/or detect where the cultivation was carried out, aiding in the search of the traffic control agencies, such as the Federal Police in Brazil
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In this work, RVC samples were treated by plasma immersion ion implantation (PIII) for electrodes production. High-voltage pulses with amplitudes of -3.0 kV or -10.0 kV were applied to the RVC samples while the treatment time was 10, 20 and 30 minutes. Nitrogen, atmospheric air and H2:N2 mixture were employed as plasma sources. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The SEM images present an apparent enhancement of the surface roughness after the treatment probably due to the surface sputtering during the PIII process. This observation is in agreement with the specific electrochemical surface area (SESA) of RVC electrodes. An increase was observed of the SESA values for the PIII treated samples compared to the untreated specimen. Some oxygen and nitrogen containing groups were introduced on the RVC surface after the PIII treatment. Both plasma-induced process: the surface roughening and the introduction of the polar species on the RVC surface are beneficial for the RVC electrodes application
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)