Phase diagrams of aqueous two-phase systems composed of poly(ethylene) glycol (PEG) 6000 g • mol -1 , lithium sulfate, sodium sulfate, and magnesium sulfate or zinc sulfate were determined at (283.15, 298.15, and 313.15) K. The effect of temperature on binodal position was not significant, indicating a small enthalpic contribution associating to the phase segregation. The ability of four sulfate salts to induce the formation of the biphasic system with PEG 6000 is as follows: ZnSO 4 > MgSO 4 > Na 2 SO 4 > Li 2 SO 4 .

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Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

Olive oil is obtained by physical means without the usage of solvents. Different than edible vegetable oils, it can be consumed in the virgin form, also being an oil of a better nutritional quality and stability, since it is mainly composed by monounsaturated fatty acids (oleic acid) as well as many antioxidant compounds. Having its greatest value in raw state, the extra virgin olive oil is the one with best quality in organoleptic aspect. As a result, this kind of oil is the one that shows biggest interest to the population and has the highest commercial value, therefore being more susceptible to adulterations. This paper aims to assess the chemical characteristics which define its classification, chemical quality and possible presence of adulterations in different brands commercialized in Brazil, applying methods described in accordance with identity and quality standards, in conformity with current legislation. This paper consists in bromatological analyzes of quality research related to classification, oxidative state, and adulteration, applying analyzes of acidity, peroxide and iodine. According to the results obtained related to classification and oxidative state, all samples were found within limits of tolerance prescribed by all legislations. Regarding adulterations, based on the iodine analyzes, two samples showed higher values determined by legislations and one showed  lower value. Values higher than those determined by legislations may show mixtures with lower quality vegetable oils, and lower values may indicate mixture with fats that are rich in saturated fatty acids or a correlation with its oxidative state. Seeing that it is a kind of food that has become a major interest for investigation due to its nutritional benefits, particularly in the prevention of cardiovascular diseases, besides assuring safety to the consumer, this research shows the importance of physicochemical analyzes in the quality of extra virgin olive oils found in the market.