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Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present in trace concentrations, play a fundamental role in important processes that occur in atmosphere. Phenomena such as global warming, photochemical smog formation, acid rain and the depletion of the stratospheric ozone layer are strongly related to the increased concentration of certain gaseous species in the atmosphere. The transport sector significantly produces atmospheric pollution, mainly when diesel oil is used as fuel. Therefore, new methodologies based on selective and sensitive gas detection schemes must be developed in order to detect and monitor pollutant gases from this source. In this work, CO2 Laser Photoacoustic Spectroscopy was used to evaluate ethylene emissions and electrochemical analyzers were used to evaluate the emissions of CO, NOx and SO2 from the exhaust of diesel powered vehicles (rural diesel with 5% of biodiesel, in this paper called only diesel) at different engine rotation speeds. Concentrations in the range 6 to 45 ppmV for ethylene, 109 to 1,231 ppmV for carbon monoxide, 75 to 868 ppmV for nitrogen oxides and 3 to 354 ppmV for sulfur dioxide were obtained. The results indicate that the detection techniques used were sufficiently selective and sensitive to detect the gaseous species mentioned above in the ppmV range.

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The increased use of modern society vehicles is rising the pollutant gas emissions causing several environmental and public health problem in urban centers. Diesel fuel is a major emitter of pollutant gases, especially in Brazil, where the transport is predominantly by land. For this reason, Brazilian government aims to modify the energy matrix with the addition of renewable energy sources, such as biodiesel. In this paper, we studied the emission of ethylene gas from the combustion of binary mixtures, because this gas is directly related to the formation of photochemical smog. The Brazilian government does not have specific regulations for the emission of ethylene yet. Thus, it becomes necessary to monitor and to detect this gas through sensitive and selective methods, such as Photoacoustic Spectroscopy. This method was employed in the analysis of binary mixtures of soybean biodiesel in diesel in the following proportions: B5, B10, B15, B20 and B25, which have been tested for combustion in an engine bench. In all samples, ethylene was found in ppmv concentrations.Keywords: biodiesel, engine bench, ethylene, phoacoustic spectroscopy IntroducationThe gases resulting from vehicles combustion might cause multiple damage to human health and the environment, causing global climate changes, such as the intensification of the greenhouse effect (Michael, Bradley, & Hughes, 1998; IPCC, 2007;Hansen et al., 2008;Nathan et al., 2008;Rosenzweig et al., 2008;Meinshausen et al., 2009;Myles et al., 2009;Solomon, Plattner, Knuttic, & Friedlingstein, 2009;. Thereby, it is necessary to monitor the emission rates of such polluting gases, with the aim of developing means to reduce them.Due to the increasing atmospheric pollution and the fact that the fossil fuels are non-renewable sources of energy, it is necessary to make changes in Brazilian energy matrix. In 2005, the Brazilian Biodiesel Program (Law no. 11097) (ANP, 2005) was instituted, establishing the addition of 2% of biodiesel in diesel form with a binary mixture named B2 and in January 2010 was set by addition of 5% biodiesel in diesel (B5), which is currently considered the standard Brazil diesel.

Lipoatropic diabetes (LD) designates a group of syndromes characterized by diabetes mellitus with marked insulin resistance and either a localized or generalized absence of adipose tissue. In this study, we evaluated plasma leptin levels in subjects with congenital generalized lipoatropic diabetes (CGLD, n = 11) or acquired generalized lipoatropic diabetes (AGLD, n = 11), and assessed correlations between leptin levels and estimations of insulin secretion and insulin sensitivity using homeostasis model assessment (HOMA). Leptin levels were 0.86 +/- 0.32, 1.76 +/- 0.78, and 6.9 +/- 4.4 ng/mL in subjects with CGLD, AGLD, and controls (n = 19), respectively (ANOVA P < 0.0001). Specific insulin levels were 154 +/- 172, 177 +/- 137 and 43 +/- 22 pmol/L, respectively (P < 0.0001). Insulin sensitivity was significantly decreased in both groups with LD (P < 0.0001), whereas HOMA beta-cell function was not significantly different when compared with controls. Leptin levels were significantly correlated with body mass index, insulin levels, and HOMA beta-cell function, and inversely correlated with insulin sensitivity in control subjects but not in subjects with generalized LD. In conclusion, decreased leptin levels were observed in subjects with generalized LD, with a trend towards lower levels in the acquired than in the congenital form (P = 0.06). The temporal relationship between the decrease in leptin levels and the development of lipoatrophy should be investigated in at-risk young relatives of subjects with the acquired forms to assess the usefulness of leptin levels as a marker of lipoatrophy.