Avaliação do soro de leite como coagulante do látex de borracha natural

Pós-graduação em Ciência dos Materiais - FEIS

Parâmetros nutricionais e metabólicos de novilhos nelore recriados em pastos de diferentes alturas e doses de suplemento

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

Activation of 5-HT2C receptors in the dorsal periaqueductal gray increases antinociception in mice exposed to the elevated plus-maze

Several findings have pointed to the role of the dorsal periaqueductal gray (dPAG) serotonin 5-HT1A and 5-HT2(A-C) receptor subtypes in the modulation of defensive behavior in animals exposed to the elevated plus-maze (EPM). Besides displaying anxiety-like behavior, rodents also exhibit antinociception in the EPM. This study investigated the effects of intra-dPAG injections of 5-HT1A and 5-HT2B/2C receptor ligands on EPM-induced antinociception in mice. Male Swiss mice received 0.1 mu l intra-dPAG injections of vehicle, 5.6 and 10 nmol of 8-OHDPAT, a 5-HT1A receptor agonist (Experiment 1), or 0.01, 0.03 and 0.1 nmol of mCPP, a 5-HT2B/2C receptor agonist (Experiment 2). Five minutes later, each mouse received an intraperitoneal injection of 0.6% acetic acid (0.1 ml/10 g body weight; nociceptive stimulus) and was individually confined in the open (OA) or enclosed (EA) arms of the EPM for 5 min, during which the number of abdominal writhes induced by the acetic acid was recorded. While intra-dPAG injection of 8-OHDPAT did not change open-arm antinociception (OAR). mCPP (0.01 nmol) enhanced it. Combined injections of ketanserin (10 nmol/0.1 mu l), a 5-HT2A/2C receptor antagonist, and 0.01 nmol of mCPP (Experiment 3), selectively and completely blocked the OAR enhancement induced by mCPP. Although intra-dPAG injection of mCPP (0.01 nmol) also produced antinociception in EA-confined mice (Experiment 2), this effect was not confirmed in Experiment 3. Moreover, no other compound changed the nociceptive response in EA-confined animals. These results suggest that the 5-HT2C receptors located within the PAG play a role in this type of environmentally induced pain inhibition in mice. (c) 2012 Elsevier B.V. All rights reserved.

Electrocatalytic Activity of Platinum-Niobium Nanoparticles for Ethanol Oxidation

Three nanostructured platinum-niobium supported on Vulcan XC-72R carbon black materials were prepared as catalysts for the ethanol electroxidation: (i) deposition of platinum and niobium on Vulcan XC-72R carbon black, (ii) platinum decorated on a mixture of commercial amorphous Nb2O5/carbon black, and (iii) the same than ii but using crystalline Nb2O5, by reduction of the precursors with sodium borohydride in ethanol. All the catalysts showed platinum crystal sizes in the range of 3-4 nm, with no or little modification of the lattice parameter. The analyses of the electronic structure from the XANES region of the XAS spectra displayed some interactions between platinum and niobium, despite the niobium was primarily in the form of pentoxide in all the catalysts. CO stripping exhibited a promising low onset potential and a large current density, especially in the case of the deposited catalyst. Ethanol electroxidation experiments revealed that the Pt-Nb(2)O(5)crystalline/C generated the largest current. However it was not effective to completely oxidize ethanol, leading to acetic acid as the main product. In this sense, the highest efficiency for the complete oxidation of ethanol was obtained for the deposited catalyst. These results were interpreted in terms of the physico-chemical characteristic displayed by the different catalysts. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.040210jes] All rights reserved.

Eucalyptus growth promotion by endophytic Bacillus spp

Clonal eucalyptus plantings have increased in recent years; however, some clones with high production characteristics have vegetative propagation problems because of weak root and aerial development. Endophytic microorganisms live inside healthy plants without causing any damage to their hosts and can be beneficial, acting as plant growth promoters. We isolated endophytic bacteria from eucalyptus plants and evaluated their potential in plant growth promotion of clonal plantlets of Eucalyptus urophylla x E. grandis, known as the hybrid, E. urograndis. Eighteen isolates of E. urograndis, clone 4622, were tested for plant growth promotion using the same clone. These isolates were also evaluated for indole acetic acid production and their potential for nitrogen fixation and phosphate solubilization. The isolates were identified by partial sequencing of 16S rRNA. Bacillus subtilis was the most prevalent species. Several Bacillus species, including B. licheniformis and B. subtilis, were found for the first time as endophytes of eucalyptus. Bacillus sp strain EUCB 10 significantly increased the growth of the root and aerial parts of eucalyptus plantlets under greenhouse conditions, during the summer and winter seasons.

Evaluation of Oat Hull Hemicellulosic Hydrolysate Fermentability Employing Pichia stipitis

Oat hull hemicellulosic hydrolysate obtained by diluted acid hydrolysis was employed as fermentation medium for Pichia stipitis cultivation. A comparison between the use of treated hydrolysate with 1% activated charcoal to reduce the toxic compounds generated during the hydrolysis process and untreated hydrolysate as a control was conducted. In the cultures using treated hydrolysate the total consumption of glucose, low xylose consumption and ethanol and glycerol formation were observed. The medium formulated with untreated hydrolysate showed morphological cell modifications with consequently cell death, no ethanol formation and formation of glycerol as byproduct of fermentative process, probably as a response to stressful conditions to yeast due to presence of high concentration of toxic compounds. Thus, further studies are suggested in order to determine the best conditions for hydrolysis and detoxification of the hydrolysate to improve the fermentative performance of P. stipitis.

Isolation, selection and characterization of root-associated growth promoting bacteria in Brazil Pine (Araucaria angustifolia)

Araucaria angustifolia, a unique species of this genus that occurs naturally in Brazil, has a high socio-economic and environmental value and is critically endangered of extinction, since it has been submitted to intense predatory exploitation during the last century. Root-associated bacteria from A. angustifolia were isolated, selected and characterized for their biotechnological potential of growth promotion and biocontrol of plant pathogenic fungi. Ninety-seven strains were isolated and subjected to chemical tests. All isolates presented at least one positive feature, characterizing them as potential PGPR. Eighteen isolates produced indole-3-acetic acid (IAA), 27 were able to solubilize inorganic phosphate, 21 isolates were presumable diazotrophs, with pellicle formation in nitrogen-free culture medium, 83 were phosphatases producers, 37 were positive for siderophores and 45 endospore-forming isolates were antagonistic to Fusarium oxysporum, a pathogen of conifers. We also observed the presence of bacterial strains with multiple beneficial mechanisms of action. Analyzing the fatty acid methyl ester (FAME) and partial sequencing of the 16S rRNA gene of these isolates, it was possible to characterize the most effective isolates as belonging to Bacillaceae (9 isolates), Enterobacteriaceae (11) and Pseudomonadaceae (1). As far as we know, this is the first study to include the species Ewingella americana as a PGPR. (C) 2011 Elsevier GmbH. All rights reserved.

Electrocatalytic Activity of Pd, Pt, and Rh for the Electro-oxidation of Ethanol in Alkaline Electrolyte: An Online DEMS Study

The electro-oxidation of ethanol was investigated on electrodeposited layers of Pd, Pt, and Rh in alkaline electrolyte. The reaction products were monitored by experiments of online differential electrochemical mass spectrometry (DEMS). Potentiodynamic curves for the ethanol electro-oxidation catalyzed by these three different metal electrocatalysts showed similar onset potentials, but the highest Faradaic current peak was observed for the Pt electrocatalyst. Online DEMS experiments evidenced similar amounts of CO2 for the three different materials, but Pd presented the higher production of ethylacetate (acetic acid). This indicated that the electrochemical oxidation of ethanol on the Pd surface occurred to a higher extent. The formation of methane, which was observed for Pt and Rh, after potential excursions to lower potentials, was absent for Pd. On the basis of the obtained results, it was stated that, on Pt and Rh, the formation of CO2 occurs mainly via oxidation of CO and CH (x,ad) species formed after dissociative adsorption of ethanol or ethoxy species that takes place only at low potentials. This indicates that the dissociative adsorption of ethanol or ethoxy species is inhibited at higher potentials on Pt and Rh. On the other hand, on the Pd electrocatalyst, the reaction may occur via nondissociative adsorption of ethanol or ethoxy species at lower potentials, followed by oxidation to acetaldehyde and, after that, by a further oxidation step to acetic acid on the electrocatalyst surface. Additionally, in a parallel route, the acetaldehyde molecules adsorbed on the Pd surface can be deprotonated, yielding a reaction intermediate in which the carbon-carbon bond is less protected, and therefore, it can be dissociated on the Pd surface, producing CO2, after potential excursions to higher potentials.

PtSnIr/C Anode Electrocatalysts: Promoting Effect in Direct Ethanol Fuel Cells

This study investigates the promoting effect of PtSnIr/C (1:1:1) electrocatalyst anode, prepared by polymeric precursor method, on the ethanol oxidation reaction in a direct ethanol fuel cell (DEFC). All of the materials used were 20% metal m/m on carbon. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of Pt, PtOH2, PtO2, SnO2 and IrO2 at the electrocatalyst surface, indicating a possible decorated particle structure. X-ray diffractometry (XRD) analysis indicated metallic Pt and Ir as well as the formation of an alloy with Sn. Using the PtSnIr/C electrocatalyst prepared here with two times lower loading of Pt than PtSn/C E-tek electrocatalyst, it was possible to obtain the same maximum power density found for the commercial material. The main reaction product was acetic acid probably due to the presence of oxides, in this point the bifunctional mechanism is predominant, but an electronic effect should not be discarded.

Assessment of the stereoselective fungal biotransformation of albendazole and its analysis by HPLC in polar organic mode

A high-performance liquid chromatographic method using polar organic mode was developed to analyze albendazole (ABZ), albendazole sulfone (ABZSO(2)) and the chiral and active metabolite albendazole sulfoxide (ABZSOX, ricobendazole) that was further applied in stereoselective fungal biotransformation studies. The chromatographic separation was performed on a Chiralpak AS column using acetonitrile:ethanol (97:3, v/v) plus 0.2% triethylamine and 0.2% acetic acid as the mobile phase at a flow rate of 0.5 mL min(-1). The present study employed hollow fiber liquid-phase microextraction as sample preparation. The method showed to be linear over the concentration range of 25-5000 ng mL(-1) for each ABZSOX enantiomer, 200-10,000 ng mL(-1) for ABZ and 50-1000 ng mL(-1) for ABZSO(2) metabolite with correlation coefficient (r)> 0.9934. The mean recoveries for ABZ, rac-ABZSOX and ABZSO(2) were, respectively, 9%, 33% and 20% with relative standard deviation below 10%. Within-day and between-day precision and accuracy assays for these analytes were studied at three concentration levels and were lower than 15%. This study opens the door regarding the possibility of using fungi in obtaining of the active metabolite ricobendazole. Nigrospora sphaerica (Sacc.) E. W. Mason (5567), Pestalotiopsis foedans (VR8), Papulaspora immersa Hotson (SS13) and Mucor rouxii were able to stereoselectively metabolize ABZ into its chiral metabolite. Among them, the fungus Mucor rouxii was the most efficient in the production of (+)-ABZSOX. (C) 2011 Elsevier B.V. All rights reserved.

Three in one: fixing marine nematodes for ecological, molecular, and morphological studies

Multidisciplinary benthic studies are still hindered by the lack of a unique fixative that satisfactorily preserves morphology and DNA, and that is simultaneously adequate for ecological surveys. The objective of this study is to test the performance of five fixatives: formalin, ethanol, dimethylsulfoxide with EDTA and NaCl salts (DESS), methanol with acetic acid (METHAC), and ethanol with acetic acid (ETHAC), for the preservation of estuarine and exclusively marine nematode assemblages for morphological, molecular, and ecological studies. The presence of the stain rose bengal in each fixative was also evaluated in the yield of PCR reactions. For molecular analyses, one species of each habitat was considered. Results revealed that fixative performance for morphological studies is habitat-and species-dependent. For studies of estuarine sediment nematodes, we recommend the use of pure ethanol, because it caused little morphological distortion (<10% of the assemblage), preserved all the species for ecological studies, and yielded high quality DNA sequences. For studies of exclusively marine environments, METHAC or DESS are the most adequate. The first performed better for morphological and ecological surveys, whereas the second was more appropriate for molecular research. For ecological studies, DESS should be used in comparison with formalin, in order to cross check the results. Finally, staining of samples with rose bengal is not recommended, because it hindered DNA amplification regardless of the fixative used.

Photo luminescent polymer electrolyte based on agar and containing europium picrate for electrochemical devices

Dispersion of photoluminescent rare earth metal complexes in polymer matrices is of great interest due to the possibility of avoiding the saturation of the photoluminescent signal. The possibility of using a natural ionic conducting polymer matrix was investigated in this study. Samples of agar-based electrolytes containing europium picrate were prepared and characterized by physical and chemical analyses. The FTIR spectra indicated strong interaction of agar O-H and 3.6-anhydro-galactose C-O groups with glycerol and europium picrate. The DSC analyses revealed no glass transition temperature of the samples in the -60 to 250 degrees C range. From the thermogravimetry (TG), a thermal stability of the samples of up to 180 degrees C was stated. The membranes were subjected to ionic conductivity measurement, which provided the values of 2.6 x 10(-6) S/cm for the samples with acetic acid and 1.6 x 10(-5) S/cm for the samples without acetic acid. Moreover, the temperature-dependent ionic conductivity measurements revealed both Arrhenius and VTF models of the conductivity depending on the sample. Surface visualization through scanning electron microscopy (SEM) demonstrated good uniformity. The samples were also applied in small electrochromic devices and showed good electrochemical stability. The present work confirmed that these materials may perform as satisfactory multifunctional component layers in the field of electrochemical devices. (C) 2012 Elsevier B.V. All rights reserved.

Aerosol and precipitation chemistry measurements in a remote site in Central Amazonia: the role of biogenic contribution

In this analysis a 3.5 years data set of aerosol and precipitation chemistry, obtained in a remote site in Central Amazonia (Balbina, (1A degrees 55' S, 59A degrees 29' W, 174 m a.s.l.), about 200 km north of Manaus) is discussed. Aerosols were sampled using stacked filter units (SFU), which separate fine (d < 2.5 mu m) and coarse mode (2.5 mu m < d < 10.0 mu m) aerosol particles. Filters were analyzed for particulate mass (PM), Equivalent Black Carbon (BCE) and elemental composition by Particle Induced X-Ray Emission (PIXE). Rainwater samples were collected using a wet-only sampler and samples were analyzed for pH and ionic composition, which was determined using ionic chromatography (IC). Natural sources dominated the aerosol mass during the wet season, when it was predominantly of natural biogenic origin mostly in the coarse mode, which comprised up to 81% of PM10. Biogenic aerosol from both primary emissions and secondary organic aerosol dominates the fine mode in the wet season, with very low concentrations (average 2.2 mu g m(-3)). Soil dust was responsible for a minor fraction of the aerosol mass (less than 17%). Sudden increases in the concentration of elements as Al, Ti and Fe were also observed, both in fine and coarse mode (mostly during the April-may months), which we attribute to episodes of Saharan dust transport. During the dry periods, a significant contribution to the fine aerosols loading was observed, due to the large-scale transport of smoke from biomass burning in other portions of the Amazon basin. This contribution is associated with the enhancement of the concentration of S, K, Zn and BCE. Chlorine, which is commonly associated to sea salt and also to biomass burning emissions, presented higher concentration not only during the dry season but also for the April-June months, due to the establishment of more favorable meteorological conditions to the transport of Atlantic air masses to Central Amazonia. The chemical composition of rainwater was similar to those ones observed in other remote sites in tropical forests. The volume-weighted mean (VWM) pH was 4.90. The most important contribution to acidity was from weak organic acids. The organic acidity was predominantly associated with the presence of acetic acid instead of formic acid, which is more often observed in pristine tropical areas. Wet deposition rates for major species did not differ significantly between dry and wet season, except for NH4+, citrate and acetate, which had smaller deposition rates during dry season. While biomass burning emissions were clearly identified in the aerosol component, it did not present a clear signature in rainwater. The biogenic component and the long-range transport of sea salt were observed both in aerosols and rainwater composition. The results shown here indicate that in Central Amazonia it is still possible to observe quite pristine atmospheric conditions, relatively free of anthropogenic influences.

Horizontal gene transfer confers fermentative metabolism in the respiratory-deficient plant trypanosomatid Phytomonas serpens

Among trypanosomatids, the genus Phytomonas is the only one specifically adapted to infect plants. These hosts provide a particular habitat with a plentiful supply of carbohydrates. Phytomonas sp. lacks a cytochrome-mediated respiratory chain and Krebs cycle, and ATP production relies predominantly on glycolysis. We have characterised the complete gene encoding a putative pyruvate/indolepyruvate decarboxylase (PDC/IPDC) (548 amino acids) of P. serpens, that displays high amino acid sequence similarity with phytobacteria and Leishmania enzymes. No orthologous PDC/IPDC genes were found in Trypanosoma cruzi or T. brucei. Conservation of the PDC/IPDC gene sequence was verified in 14 Phytomonas isolates. A phylogenetic analysis shows that Phytomonas protein is robustly monophyletic with Leishmania spp. and C. fasciculata enzymes. In the trees this clade appears as a sister group of indolepyruvate decarboxylases of gamma-proteobacteria. This supports the proposition that a horizontal gene transfer event from a donor phytobacteria to a recipient ancestral trypanosome has occurred prior to the separation between Phytomonas. Leishmania and Crithidia. We have measured the PDC activity in P. serpens cell extracts. The enzyme has a Km value for pyruvate of 1.4 mM. The acquisition of a PDC, a key enzyme in alcoholic fermentation, explains earlier observations that ethanol is one of the major end-products of glucose catabolism under aerobic and anaerobic conditions. This represents an alternative and necessary route to reoxidise part of the NADH produced in the highly demanding glycolytic pathway and highlights the importance of this type of event in metabolic adaptation. (C) 2012 Elsevier B.V. All rights reserved.

Development of Plurimetallic Electrocatalysts Prepared by Decomposition of Polymeric Precursors for EtOH/O-2 Fuel Cell

This work aimed to develop plurimetallic electrocatalysts composed of Pt, Ru, Ni, and Sn supported on C by decomposition of polymeric precursors (DPP), at a constant metal: carbon ratio of 40:60 wt.%, for application in direct ethanol fuel cell (DEFC). The obtained nanoparticles were physico-chemically characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD results revealed a face-centered cubic crystalline Pt with evidence that Ni, Ru, and Sn atoms were incorporated into the Pt structure. Electrochemical characterization of the nanoparticles was accomplished by cyclic voltammetry (CV) and chronoamperometry (CA) in slightly acidic medium (0.05 mol L-1 H2SO4), in the absence and presence of ethanol. Addition of Sn to PtRuNi/C catalysts significantly shifted the ethanol and CO onset potentials toward lower values, thus increasing the catalytic activity, especially for the quaternary composition Pt64Sn15Ru13Ni8/C. Electrolysis of ethanol solutions at 0.4 V vs. RHE allowed determination of acetaldehyde and acetic acid as the main reaction products. The presence of Ru in alloys promoted formation of acetic acid as the main product of ethanol oxidation. The Pt64Sn15Ru13Ni8/C catalyst displayed the best performance for DEFC.