Beef tallow is a promising alternative as a non-edible raw material for biodiesel production, due to its lower price compared to vegetable oils such as soybean oil. The problem of using beef tallow ...as a raw material for biodiesel is its high acidity level, found as a consequence of hydrolysis and oxidation reactions. These degradation processes are significant in the presence of high levels of humidity and temperature, which are usually found in the storage conditions. In this study, the influence of synthetic and natural antioxidants on the oxidation stability of beef tallow was evaluated using Rancimat tests and by monitoring their acid and peroxide values over 148 days of storage in an oven. The studied synthetic and natural (cashew nut shell liquid, CNSL) antioxidants were effective to prevent oxidation of beef tallow on storage conditions. Biodiesel samples were produced from samples of beef tallow with and without antioxidants. The biodiesel samples produced from beef tallow containing BHT presented the best induction period values. The biodiesel samples produced from beef tallow containing technical CNSL (0.5 wt%) met the requirement of oxidation stability at 110 °C determined by the Brazilian specification.
Polycrystalline gold electrode surface spontaneously modified by 1,4-dithiane (1,4-dt) organosulfur species was characterized by rotating disk electrode (RDE) and electrohydrodynamic impedance (EHD) ...using
Fe(CN)
6
3
-
as the electrochemical probe molecule. The gold(1
1
1) monocrystal surface was also modified with 1,4-dt to assess the surface morphology by atomic force microscope (AFM). The electrochemical measurements showed that the polycrystalline gold surface modified with 1,4-dt exhibits a typical behavior of a partially blocked surface and that the blocking effect increases with the increase of the immersion time in the precursor solution. The AFM image clearly shows the presence of defects on the modified surface. Even for a high immersion time (72
h) the electrode surface was not entirely blocked. The surface roughness of the Au/1,4-dt is approximately three times greater than the surface roughness of the bare-gold electrode.
This paper presents studies on the influence of the instability of the 4-mercaptopyridine (pyS) layer adsorbed on polycrystalline gold surface (Au/pyS) on rapid electron transfer reaction. ...Voltammetric and impedance experiments were performed using
Fe
(
CN
)
6
3
-
as the electrochemical probe molecule. The morphology of the layer was assessed by the atomic force microscopy (AFM) technique using gold (1
1
1) modified with the pyS. The techniques used in this work presented a qualitatively agreement concerning the instability of the pyS layer. The electrochemical results showed that instability of the pyS layer leads to an increase on rapid electron transfer reaction of the probe molecule. AFM images showed that the instability of the pyS layer leads to the arisen of defects on layer and an increase in the roughness layer.
Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, a disease that affects 10 million individuals in Latin America. This report depicts the results of the analysis of ...6,022 assembled groups from mycelium and yeast phase expressed sequence tags, covering about 80% of the estimated genome of this dimorphic, thermo-regulated fungus. The data provide a comprehensive view of the fungal metabolism, including overexpressed transcripts, stage-specific genes, and also those that are up- or down-regulated as assessed by in silico electronic subtraction and cDNA microarrays. Also, a significant differential expression pattern in mycelium and yeast cells was detected, which was confirmed by Northern blot analysis, providing insights into differential metabolic adaptations. The overall transcriptome analysis provided information about sequences related to the cell cycle, stress response, drug resistance, and signal transduction pathways of the pathogen. Novel P. brasiliensis genes have been identified, probably corresponding to proteins that should be addressed as virulence factor candidates and potential new drug targets.
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