Bacterial leaching of uranium ore from Figueira-PR, Brazil, at laboratory and pilot scale

A bacterial leaching program was carried out in order to evaluate the potential of applying this process to leach uranium from the ore of Figueira-PR, Brazil. The experiments were carried out in shake flasks, column percolation (laboratory and semipilot scale) and in heap leaching. In shake flasks and in column percolation experiments at laboratory scale, bacterial activity on the ore was confirmed: approximately 60% of uranium was leached, against around 30% in sterilized controls. Column percolation experiments at semipilot scale and heap leaching (850 tons of ore) showed uranium extractions of approximately 50%. In both experiments, a complementary sulfuric acid attack, after the bacterial leaching phase, was necessary to reach this level of uranium extraction.

Germinative pretreatments to dormancy break in Guazuma ulmifolia Lam. seeds

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Rapid determination of zinc in foods by flow injection analysis with flame AAS using gradient calibration method

A calibration method was developed using flow injection analysis (FI) with a Gradient Calibration Method (GCM). The method allows the rapid determination of zinc In foods (approximately 30 min) after treatment with concentrated sulphuric acid and 30% hydrogen peroxide, and analysis with flame atomic absorption spectrometry (FAAS). The method provides analytical results with a relative standard deviation of about 2% and requires less time than by conventional FI calibration. The electronic selection of different segments along the gradient and monitoring of the technique covers wide concentration ranges while maintaining the inherent high precision of flow injection analysis. Concentrations, flow rates, and flow times of the reagents were optimized in order to obtain best accuracy and precision. Flow rates of 10 mL/min were selected for zinc. In addition, the system enables electronic dilution and calibration where a multipoint curve can be constructed using a single sample injection.

Methanol oxidation on PtRu/C electrocatalysts prepared by a microemulsion method

PtRu/C nanocatalysts were prepared by a microemulsion method using different values of water/surfactant molar ratio in order to get different particle sizes. Crystallite sizes and structural properties were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energy dispersive X-ray analysis. Differential scanning calorimetry measurements indicated the presence of oxides in the as-prepared catalysts. The general electrochemical behavior was evaluated by cyclic voltammetry in 0.5 M sulfuric acid and the electrocatalytic activity towards the oxidation of methanol was studied in 0.5 M methanol acid solutions by potential sweeps and chronoamperometry. copyright The Electrochemical Society.

Effects of heat treatments on the electrocatalytic activity of Pt-Ru/C for methanol oxidation

The Pt-Ru/C materials of this study were prepared by a microemulsion method with fixed water to surfactant molar ratio and heat treated at low temperatures, to avoid changes in the average particle size, in different atmospheres. All samples were characterized by X-ray diffraction (XRD) and the mean crystallite size was estimated by using Scherrer's equation. Catalysts morphology was characterized by transmission electron microscopy (TEM). Average composition was obtained by energydispersive X-ray analysis (EDX). The general electrochemical behavior was evaluated by cyclic voltammetry in 0.5 M sulfuric acid and the electrocatalytic activity towards the oxidation of methanol was studied in 0.5 M methanol acid solutions by potential sweeps and chronoamperometry. Oxidation of adsorbed CO was used to estimate the electrochemical active area and to infer the surface properties. ©The Electrochemical Society.

Superação da dormência em sementes de Murdannia nudiflora (L.) Brenan

The objective of this study was to identify treatments capable of promoting and standardizing the germination of Murdannia nudiflora (L.) Brenan seeds. The seeds of this weed were submitted to the following treatments: mechanical abrasion with 220-grit sandpaper (20, 30 and 40 frictions); immersion in sulfuric acid (90% for 30 and 40 seconds), followed by washing in running water; immersion in sodium hypochlorite (2.5% for 8 and 12 hours) and lye (5 minutes), followed by five washings in distilled water; immersion in KNO 3 (1% for 24 hours); preheating at 40°C in a humid or dry substrate for 2, 3 and 4 weeks. The statistical design was totally randomized, with four repetitions. The number of germinated seeds was counted every other day. The most favorable treatments were preheating at 40°C in humid substrate for 3 weeks, followed by mechanical abrasion after 40 frictions and immersion in sulfuric acid for 40 seconds.

Oxygen reduction on PtFe/C electrocatalysts prepared in microemulsions

PtFe/C nanocatalysts of different compositions and nearly constant particle size were prepared by a microemulsion method. Crystallite sizes and degree of alloying were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energy dispersive X-ray analysis. Measurements of electrocatalytic activity for oxygen reduction were done using the rotating disk electrode technique in O2 saturated 0.5 mol L-1 sulfuric acid solutions, at room temperature. For all catalysts oxygen reduction begins at ̃ 0.90V. Tafel plots show slopes of c.a. 60 and 120 mV dec in the regions of low and high overpotentials, respectively. The best results for the ORR were obtained for the PtFe/C catalyst of composition Pt:Fe 70:30. This catalyst was also found to exhibit the largest methanol tolerance. © The Electrochemical Society.

Integrated analysis of halogenated organic pollutants in sub-millilitre volumes of venous and umbilical cord blood sera

A rapid, robust and economical method for the analysis of persistent halogenated organic compounds in small volumes of human serum and umbilical cord blood is described. The pollutants studied cover a broad range of molecules of contemporary epidemiological and legislative concern, including polychlorobiphenyls (PCBs), polychlorobenzenes (CBs), hexachlorocyclohexanes (HCHs), DDTs, polychlorostyrenes (PCSs) and polybromodiphenyl ethers (PBDEs). Extraction and clean-up with n-hexane and concentrated sulphuric acid was followed with analysis by gas chromatography coupled to electron capture (GC-ECD) and GC coupled to negative ion chemical ionisation mass spectrometry (GC-NICI-MS). The advantages of this method rest in the broad range of analytes and its simplicity and robustness, while the use of concentrated sulphuric acid extraction/clean-up destroys viruses that may be present in the samples. Small volumes of reference serum between 50 and 1000 μL were extracted and the limits of detection/quantification and repeatability were determined. Recoveries of spiked compounds for the extraction of small volumes (≥300 μL) of the spiked reference serum were between 90% and 120%. The coefficients of variation of repeatability ranged from 0.1-14%, depending on the compound. Samples of 4-year-old serum and umbilical cord blood (n = 73 and 40, respectively) from a population inhabiting a village near a chloro-alkali plant were screened for the above-mentioned halogenated pollutants using this method and the results are briefly described. © 2010 Springer-Verlag.

Quebra de dormência em sementes de Sesbania virgata (Cav.) Pers

Forest species with hard seeds often pose considerable problems to nursery managers because their hard and impermeable seed coats hinder and delay germination. Therefore, this work aimed to determine the most efficient, practical and low cost methodology to overcome dormancy in Sesbania virgata (Cav.) Pers. Seed, a specie with potential for recovery of degraded areas. The seeds were submitted to chemical scarification by immersion in sulfuric acid during a period of 5, 10, 20 and 30 minutes, mechanical scarification and heat treatment. After the scarification the seeds were submitted to germ test in germination chambers at 25oC and photoperiod of 14 h. Treatment with mechanical scarification showed the highest germination percentage (98%), followed by chemical scarification for 30 minutes (57%). The heat treatment in spite of obtaining a higher germination percentage than the controls had abnormal development of seedlings and is not therefore recommended for seeds of S. virgata. From the parameters utilized in this study, we recommend the use of the mechanical scarification to overcome dormancy of S. virgata seeds.

Structural characterization of a new dextran with a low degree of branching produced by Leuconostoc mesenteroides FT045B dextransucrase

This paper offers the physical and chemical characterization of a new dextran produced by Leuconostoc mesenteroides FT045B. The chemical structure was determined by Fourier Transform Infrared spectroscopy and 1H Nuclear Magnetic Resonance spectroscopy. The dextran was hydrolyzed by endodextranase; the products were analyzed using thin layer chromatography and compared with those of commercial B-512F dextran. The number-average molecular weight and degree of polymerization of the FT045B dextran were determined by the measurement of the reducing value using the copper bicinchoninate method and the measurement of total carbohydrate using the phenol-sulfuric acid method. The data revealed that the structure of the dextran synthesized by FT045B dextran sucrase is composed of d-glucose residues, containing 97.9% α-(1,6) linkages in the main chains and 2.1% α-(1,3) branch linkages compared with the commercial B-512F dextran, which has 95% α-(1,6) linkages in the main chains and 5% α-(1,3) branch linkages. © 2012 Elsevier Ltd. All rights reserved.

Anatomia topográfica e comportamento arterial do pâncreas em cágados Trachemys scripta elegans (wied, 1838)

The turtle Trachemys scripta elegans popularly known as American tiger water are native regions winged Florida and Mississippi, in the United States. We used twenty (20) turtles (Trachemys scripta elegans), adult males and females, which were euthanized under Resolution 714 of June 20, 2002 the Federal Council of Veterinary Medicine (CFMV). After euthanasia were identified aortas right and left to the injection of Neoprene latex 450, stained with specific pigment. To obtain the vinyl mold aorta was injected through the right and left vinyl acetate, followed by corrosion in sulfuric acid. It was observed that the pancreas is closely related to the liver, gizzard, gall bladder, and duodenum. His face cranial this distal region of the pylorus, while its caudal along the cranial region of the duodenum. Anatomically, the pancreas is an elongated body structure featuring a lightly lobed. As to the pancreas arterial vasculature is flushed in its transverse plane of two arteries arising from the celiac artery, and each antimere two pancreaticoduodenal artery in the cranial region, close to the pylorus by the pancreaticoduodenal artery flow in the caudal portion along the duodenum.

Influence of ethanol, acidity and chloride concentration on the corrosion resistance of AISI 316L stainless steel

The influence of ethanol, sulfuric acid and chloride on the corrosion resistance of 316L stainless steel was investigated by means of polarization curves and electrochemical impedance spectroscopy measurements. Over the studied range, the steel corrosion potential was independent of H2SO 4 and NaCl concentrations in aqueous solution. On the other hand, in solution containing 65 wt.% ethanol and 35 wt.% water, the corrosion potentials were higher than those obtained in aqueous solution. Besides, the steel corrosion potential was affected by the addition of H2SO4 and NaCl in solution. In solutions with and without ethanol, plus 0.35 wt.% NaCl, the presence of 1 wt.% H2SO4 inhibited the appearance of pitting corrosion. © 2013 Sociedade Brasileira de Química.

Duração do teste de germinação do capim-tanzânia

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

Estudo do pré-tratamento do bagaço de cana-de-açúcar e caracterização físico-química

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação, modificação e validação de metodologia para estudo de estabilidade de hidroquinona em creme

Pós-graduação em Ciências Farmacêuticas - FCFAR