Reproduction of a fish assemblage in the state of São Paulo, southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of cold fronts on MODIS-derived sensible and latent heat fluxes in Itumbiara reservoir (Central Brazil)

In this work we investigate the cold front passage effects on sensible and latent heat flux in a tropical hydroelectric reservoir. The study area, Itumbiara reservoir (Goiás State/Brazil) at the beginning of the austral winter, is characterized by the presence of a weak thermal stratification and the passage of several cold fronts from higher latitudes of South America. Sensible and latent heat fluxes were estimated considering the atmospheric boundary layer stability. In situ and MODIS water surface temperature data were used to adjust the coefficients for momentum and heat exchanges between water and atmosphere and spatialize the sensible and latent heat fluxes. The results showed that during a cold front event the sensible heat flux can be up to five times greater than the flux observed before. The latent heat flux tends to decrease during the cold front but increase again after the passage. The highest values of heat loss were observed at littoral zone and some Reservoir's embayment. The heat loss intensification can be separated in two moments: first, during the cold front passage, when the wind speed increases and the air temperature decreases; second, after the cold front passage, with air humidity decreasing. This can be considered a key process to understanding the heat loss in the Itumbiara reservoir. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.

Optimization of extraction conditions and antioxidant activity of Solanum lycocarpum fruits

Antioxidants are substances that may protect cells from the damage caused by unstable molecules known as free radicals. The capacity of natural antioxidant from phytochemical has increase attention from researchers and public. However, the extraction process is affecting the activity and the bioavailability of bioactive compounds. The Solanum lycocarpum is a plant of the Brazilian “cerrado”, popularly used as a hypoglycemic, hypocholesterolemic and control of metabolic diseases. Its effects are attributed to the presence of several glycoalkaloids (solamargine, solasonina) and solasodine. Therefore, the purpose of this communication was, investigate the optimization of extraction condition and evaluation of antioxidant activity from fruits of Solanum lycocarpum. The extracts were obtained using different solvent systems, i.e., water, 50% ethanol, ethanol absolute and ethyl ether (1:10 and 1:20) and different extraction processes: maceration with constant agitation at room temperature, maceration with constant agitation and heating at 30°C and ultrasound. The extracts were characterized by the amount of material extracted (1, 6 and 24 h) and the action of antioxidant activity by DPPH method. The results showed that the polar solvent (50% ethanol) and extractive process maceration with agitation to ambient temperature showed higher contents of extractable of fruits of S. lycocarpum (3.4 g %) and also showed higher antioxidant activity (88.57±2.41% de inhibition). This action whether the presence of glycoalkaloids (solamargine, solasonine and solasodine) in fruits S. lycocarpum which are polar compounds and may explain this increased antioxidant action of this extract.