14 research outputs found
Electrochemical determination of 8-oxoguanine in the presence of uric acid
The electrochemical oxidation of 8-oxoguanine (8-oxoG) in the presence of uric acid (UA) was studied by differential pulse voltammetry over a wide pH range (1-12). The results showed that both compounds follow a pH-dependent oxidation mechanism that involves two electrons and two protons corresponding to reversible charge transfer reactions. The difference between the peak potential for the oxidation of each analyte was found to be always less than 100 mV over the whole pH range, the separation being greater in the pH interval 4-7. In mixtures of both analytes, pH 6 was shown to be the best for 8-oxoG determination in the presence of uric acid, since the peak current is higher and a greater peak separation is achieved.http://www.sciencedirect.com/science/article/B6W72-4BT8CHG-4/1/3055f9e7d945bd40f78b853c25e10d3
Abundance of Harpy and Crested Eagles from a reservoir-impact area in the Low- and Mid-Xingu River
Abstract In the Brazilian Amazon, two monospecific genera, the Harpy Eagle and Crested Eagle have low densities and are classified by IUCN as Near Threatened due to habitat loss, deforestation, habitat degradation and hunting. In this study, we evaluate occurrence of these large raptors using the environmental surveys database from Belo Monte Hydroelectric Power Plant. Integrating the dataset from two methods, we plotted a distribution map along the Xingu River, including records over a 276-km stretch of river. Terrestrial surveys (RAPELD method) were more efficient for detecting large raptors than standardized aquatic surveys, although the latter were complementary in areas without modules. About 53% of the records were obtained during activities of wildlife rescue/flushing, vegetation suppression or in transit. Between 2012 and 2014, four Harpy Eagles were removed from the wild; two shooting victims, one injured by collision with power lines and one hit by a vehicle. Also, seven nests were mapped. The mean distance between Harpy Eagle records was 15 km along the river channel, with a mean of 20 km between nests near the channel, which allowed us to estimate 20 possible pairs using the alluvial forest, riverine forest and forest fragments. Territories of another ten pairs will probably be affected by inundation of the Volta Grande channel, which is far from the main river. The average distance between Crested Eagle records was 16 km along the river channel. The only nest found was 1.3 km away from a Harpy Eagle nest. The remnant forests are under threat of being replaced by cattle pastures, so we recommend that permanently protected riparian vegetation borders (APP) be guaranteed, and that forest fragments within 5 km of the river be conserved to maintain eagle populations
Innovative analytical tools to characterize prebiotic carbohydrates of functional food interest
Functional foods are one of the most interesting
areas of research and innovation in the food industry. A
functional food or functional ingredient is considered to be
any food or food component that provides health benefits
beyond basic nutrition. Recently, consumers have shown
interest in natural bioactive compounds as functional ingredients
in the diet owing to their various beneficial effects for
health. Water-soluble fibers and nondigestible oligosaccharides
and polysaccharides can be defined as functional food
ingredients. Fructooligosaccharides (FOS) and inulin are
resistant to direct metabolism by the host and reach the
caecocolon, where they are used by selected groups of
beneficial bacteria. Furthermore, they are able to improve
physical and structural properties of food, such as hydration,
oil-holding capacity, viscosity, texture, sensory characteristics,
and shelf-life. This article reviews major innovative
analytical developments to screen and identify FOS, inulins,
and the most employed nonstarch carbohydrates added or
naturally present in functional food formulations. Highperformance
anion-exchange chromatography with pulsed
electrochemical detection (HPAEC-PED) is one of the most
employed analytical techniques for the characterization of
those molecules. Mass spectrometry is also of great help, in
particularly matrix-assisted laser desorption/ionization timeof-
flight mass spectrometry (MALDI-TOF-MS), which is
able to provide extensive information regarding the molecular
weight and length profiles of oligosaccharides and polysaccharides.
Moreover, MALDI-TOF-MS in combination with HPAEC-PED has been shown to be of great value for the
complementary information it can provide. Some other techniques,
such as NMR spectroscopy, are also discussed, with
relevant examples of recent applications. A number of articles
have appeared in the literature in recent years regarding the
analysis of inulin, FOS, and other carbohydrates of interest in
the field and they are critically reviewed