Fuel cell is considered an energetic solution of low environmental impact which large-scale commercialization is hindered by the expensive Pt-based cathodic electrocatalyst. Therefore, its replacement by an active less-expensive metal-free electrocatalyst such as nitrogen-doped graphene (N-graphene) is desirable. To investigate nitrogen-doping influence on graphene’s activity in alkaline oxygen reduction reaction (ORR), we prepared N-graphene through thermal treatment of graphene and urea at 800 °C for 30 min. N-graphene exhibited higher onset potential, half-wave potential, diffusion-limited current density and kinetic current density in ORR (0.78 V vs RHE, 0.63 V vs RHE, -3.36 mA cm-2, -3.00 mA cm-2, respectively) than undoped graphene (0.73 V vs RHE, 0.62 V vs RHE, -2.80 mA cm-2, -2.23 mA cm-2, respectively), which may be attributed to nitrogen-doping, edges and defect sites in N-graphene, as revealed by elemental analysis, scanning electron microscopy and Raman spectroscopy results. This activity improvement also affected ORR’s selectivity and rate-determining step.

The photocatalytic degradation of methylene blue dye and ibuprofen drug was studied in the presence of zinc oxide, synthetized by the protein sol-gel route. The catalyst, calcined at 1000 ºC, presented a tendentious morphology to filaments characteristic of ZnO crystalline, characterized by X-ray diffraction (XRD) and confirmed by the presence of Zn energy band in X-ray photoelectron spectrometer (XPS). The result of ultraviolet (UV) light photodegradation of this work is comparable to others that made use of more complex routes, considering the degradation of 97% of methylene blue dye solution and the solution of the ibuprofen drug reached 60% of degradation after 1 h of light incidence. In this research, it is possible to report good degradation results, and the research differential is a material made with a simple and less aggressive route, capable of generating a stable and efficient material.

The selective ion monitoring acquisition mode in mass spectrometry was applied to identify, in the diesel complex matrix, the raw materials (vegetable oil and alcohol) that originate biodiesel. Biodiesel samples obtained from babassu, castor, palm and soybean vegetable oils and pure fatty acid methyl and ethyl esters were used to develop this method, using specific fragments in mass spectrometry and the "window system" in gas chromatography. The commercial Brazilian B2 samples were found to be produced with soybean oil, transesterified with methanol.

Os efeitos das condições operacionais sobre as propriedades da membrana e dos eletrodos em uma célula a combustível de eletrólito polimérico são estudados em função da temperatura da célula e dos umidificadores dos gases, da espessura da membrana, da impregnação com ácido fosfotúngstico (AFW) e da variação dos conteúdos de Nafion e Teflon nos eletrodos de difusão de gás. Um aumento da resistência da membrana ocorre quando a célula opera em temperatura igual ou superior àquela de umidificação dos gases, sendo este efeito mais aparente para membranas mais espessas. Na presença de AFW, as propriedades da membrana não se alteram significativamente com a temperatura do conjunto. No entanto, neste caso, uma menor temperatura de umidificação dos gases reagentes prejudica o desempenho dos eletrodos. Variações no conteúdo de Nafion nos eletrodos não levam a nenhum efeito significativo sobre as propriedades do sistema. Para altos conteúdos de Teflon há uma pequena diminuição da condutividade da membrana.

The effects of the operational conditions on the membrane and electrode properties on a polymer electrolyte fuel cell (PEFC) were investigated as a function of the cell and the gas humidifiers temperatures, the thickness of the membrane, the impregnation with phosphotungstic acid (PWA), and the variation of the Nafion and Teflon contents in the gas diffusion electrodes. An increase of the membrane resistance was observed when the PEFC is operated at temperatures equal or higher than those of the gas humidifiers, and this is more apparent for thicker electrolyte films. In the presence of PWA, the physicochemical properties of the membrane do not appreciably change with temperature. However, in this case, a lower humidification temperature affects the electrode performance. Changes on the Nafion loading in the electrodes do not lead to any significant effect in the electrode and membrane properties. For high Teflon contents there is a small lowering of the membrane conductivity.

A polimerização de adesivo à base de cianoacrilato foi acompanhada por FT-IR durante 30 minutos. A aplicação das técnicas de estatística multivariada (análise de agrupamento hierárquico e a análise dos componentes principais) aos espectros de infravermelho, permitiram uma melhor identificação das diferenças espectrais entre monômero e polímero e possibilitou, também, inferir que a quantidade de monômero e do mero no polímero se eqüivalem com seis minutos de polimerização. A técnica de infravermelho mostrou-se uma ferramenta adequada para o acompanhamento da cinética de reação de adesivo à base de cianoacrilato, que torna-se ainda mais eficiente quando associada às técnicas de estatística multivariada.

The polymerization of a cyanoacrylate adhesive was accompanied by FT-IR during 30 minutes. The application of multivariate statistics techniques (Hierarchical Clusters Analyses and Principal Components) on infrared spectra allowed a better identification of spectral differences between monomer and polymer and also permitted to infer that the quantity of monomer and of mer of the polymer are equal in six minutes polymerization (half-life). The infrared technique appeared as an apropriate tool for observing the kinetics of cyanoacrylate adhesive reaction, which becomes even more efficient when associated to multivariate statistics techniques.