Towards the abatement of environmental mercury pollution: An electrochemical characterization

Electrochemical experiments in acetic acid-acetate buffer (pH 4.5) are conducted in order to understand metallic and ionic mercury adsorption processes on the pyrite surface. The nature as well as the extent of the spontaneous interaction between pyrite and mercuric ions was evaluated. The spontaneous reduction of mercury species onto pyrite surface was confirmed. These results represent a first step for the use of mining wastes rich in pyrite for mercury pollution abatement. (c) 2005 Elsevier B.V. All rights reserved.

Optimisation of a sample preparation method for the determination of fumonisin B-1 in rice

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A study of the main oxidation products of natural pyrite by voltammetric and photoelectrochemical responses

(Photo)electrochemical experiments on pyrite electrodes in acetic acid-acetate buffer (pH = 4.5) are conducted to clarify the main oxidation reactions and the nature of the products. Electrochemical reactions in the -0.40 to 1.25 V (SHE) potential range are studied, and the production of iron (III) polysulfide from anodically formed iron oxides and polysulfides is discussed. Charges experimentally obtained are considered for the estimation of the most likely stoichiometry of the metallic polysulfide. The photoselectivity of the pyrite corrosion process indicates that the oxidation reactions of Fe2+ and S-2(2-) an not consecutive. The changes in stoichiometry and/or annihilation of crystalline structure defects are responsible for the observed photosensitivity of pyrite. A description of light effects on the interfacial behaviour and stability of pyrite is presented in terms of conduction and valence band energies, and thermodynamic potentials. (C) 2001 Elsevier Science B.V. All rights reserved.

Protonation Pattern, Tautomerism, Conformerism, and Physicochemical Analysis in New Crystal Forms of the Antibiotic Doxycycline

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Determination of pantoprazole in human plasma by LC-MS-MS using lansoprazole as internal standard

An analytical method based on liquid chromatography with positive ion electrospray ionization (ESI) coupled to tandem mass spectrometry detection was developed for the determination of pantoprazole (CAS 102625-70-7) in human plasma using lansoprazole (CAS 103577-45-3) as the internal standard. The analyte and internal standard were extracted from the plasma samples by liquid/liquid extraction using diethyl-ether/dichloromethane (70:30; v/v) and chromatographed on a C-8 analytical column. The mobile phase consisted of acetonitrile/water/methanol (57:25:18; v/v/v) + 10 mmol/l acetic acid + 20 mmol/l ammonium acetate. The method has a chromatographic total run time of 4.5 min and was linear within the range 5.0-5,000 ng/mL. Detection was performed on a triple quadrupole tandem mass spectrometer by Multiple Reaction Monitoring (MRM). The intra- and inter-run precisions calculated from quality control (QC) samples were 4.2% and 3.2%, respectively. The accuracies as determined from QC samples were -5.0% (intra-run) and 2.0% (inter-run). The method herein described was employed in a bioequivalence study of two tablet formulations of pantoprazole.

Evaluation of solvent effect on the extraction of phenolic compounds and antioxidant capacities from the berries: application of principal component analysis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of feeding corn silage inoculated with microbial additives on the ruminal fermentation, microbial protein yield, and growth performance of lambs

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

Antifungal Compounds Produced by Colletotrichum gloeosporioides, an Endophytic Fungus from Michelia champaca

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

Oxidation of ethanol and its derivatives on well defined pt single crystal electrodes vicinal to pt(111): a comparative study

The oxidation of ethanol (EtOH) at Pt(111) electrodes is dominated by the 4e path leading to acetic acid. The inclusion of surface defects such as those present on stepped surfaces leads to an increase of the reactivity towards the most desirable 12e path leading to CO2 as final product. This path is also favored when the methyl group is more oxidized, as in the case of ethylene glycol (EG) that spontaneously decomposes to CO on Pt(111) electrodes, thus showing a more effective breaking of the C-C bond. Some trends in reactivity can be envisaged when other derivative molecules are compared at well-ordered electrodes. This strategy was used in the past, but the improvement in the electrode pretreatment and the overall information available on the subject suggest that relevant information is still missing.

Development of biomimetic sensor for fast and sensitive detection of Norfloxacin

A biomimetic sensor is proposed as a promising new analytical method for determination of norfloxacin (NF) in pharmaceuticals. The sensor was prepared by modifying a glassy carbon electrode surface with a Nafion® membrane doped with poly(copper phthalocyanine) complex [poly-CuPc]. Amperometric measurements carried out with the sensor under an applied potential of -0.05 V vs Ag|AgCl in 0.1 mol L-1 acetic acid containing 1.5 × 10-3 mol L-1 hydrogen peroxide showed a linear response range from 2.0 × 10-4 to 1.2 × 10-3 mol L-1. Selectivity and interference studies were also performed. A sensor response mechanism is proposed, based on the experimental evidence. Recovery studies were carried out using environmental samples, in order to evaluate the sensor’s potential for use with these sample classes. Finally, sensor performance was evaluated using analyses of commercial formulations.

Bioconversion of Cellulose to Hydrogen by dark fermentation

Hydrogen is known as a clean energy resource. The biological production of hydrogen has been attracting attention as an environmentally friendly processs that does not consume fossil fuels. Cellulosic plant and waste materials are potential resources for fermentative hydrogen production. Cellulose is a linear biopolymer of glucose molecules, connected by β-1,4-glycosidic bonds. Enzymatic hydrolysis of cellulose requires the presence of cellulase. The present study aimed to investigate the efficiency of acid pretreatment on ruminal fluid in order to enrich H2 producing bacteria consortia to enhance biohydrogen rate and substrate removal efficiency. In this study, fermentative hydrogen producers were enriched on cellulose (2g/L) in a modificated Del Nery medium (DNM) at 37ºC and initial pH 7.0 using rumen fluid (10% v/v) as inoculum. To increase the hydrogen production it was added cellulose (10mL) to the medium. The gas products (mainly H2 and CO2) was analyzed by gas chromatography (Shimadzu GC 2010) using a thermal conductivity detector. The volatile fatty acids and ethanol were also detected by GC using a flame ionization detector. Cellulose degradation was quantified by using the phenolsulfuric acid method. Analysis showed that the biogas produced from the anaerobic fermentation contained only hydrogen and carbon dioxide, without detectable methane after acid pretreatment test. On DNM the hydrogen production started with 4 h (5,3 x 105 mmol H2/L) of incubation, and the maximum H2 concentration was observed with 34 h (7,1 x 106 mmol H2/L) of incubation. During the process, it was observed a predominance of acetic acid and butyric acid as well as a low production of acetone, ethanol and nbutanol in all experimental phases. Butyrate accounted for more than 77% of total. As a result of the accumulation of volatile fatty acids (VFAs), the pH value in anaerobic digestion system was reduced to 4,0. On microscopy analyses there were observed rods with endospores. The batch anaerobic fermentation assays performed on anaerobic mixed inoculum from rumen fluid demonstrated the feasibility of H2 generation utilizing cellulose as substrate. Based on the results, it can be concluded that the acid treatment was efficient to inhibit the methanogenic archaea cells present in rumen fluid. The rumen fluid cells present a potential route in converting renewable biomass such as cellulose into hydrogen energy.

Biological Hydrogen production from environmental sample in tropical countries

The hydrogen gas is regarded as clean and renewable energy source, since it generates only water during combustion when used as fuel. It shows 2.75 times more energy content than any hydrocarbon and it can be converted into electrical, mechanical energy or heat. Inoculum sources have been successfully tested for hydrogen biological production in temperate climate countries as sludge treatment plants sewage, sludge treatment plant wastewater, landfill sample, among others. However, hydrogen biologic production with inoculum from environmental samples such as sediment reservoirs, especially in tropical countries like Brazil, is rarely investigated. Reservoirs and fresh water lake sediment may contain conditions for the survival of a wide variety of microorganisms which use different carbon sources mainly glucose and xylose, in the fermentation. Glucose is an easily biodegradable, present in most of the industrial effluents and can be obtained abundantly from agricultural wastes. A wide variety of wastewater resulting from agriculture, industry and pulp and paper processed from wood may contain xylose in its constitution. Such effluent contains glucose and xylose concentrations of about 2 g/L. In this sense, this work verified hydrogen biological production in anaerobic batch reactor (1L), at 37 ° C, initial pH 5.5, headspace with N2 (100%), Del Nery medium, vitamins and peptone (1 g/L), fed separately with glucose (2g/L) and xylose (2 g/L). The inoculum was taken from environmental sample (sediment reservoir Itupararanga - Ibiúna - SP-Brazil). It was previously purified in serial dilutions at H2 generation (10-5, 10-7, 10-10), and heat treated (90º C - 10 min) later to inhibited the H2 consumers. The maximum H2 generations obtained in both tests were observed at 552 h, as described below. At the reactors fed with glucose and xylose were observed, respectively, 9.1 and 8.6 mmol H2/L, biomass growth (0.2 and 0.2 nm); consumption of sugar concentrations 53.6% (1.1 glucose g/L) and 90.5% (1.8 xylose g/L); acetic acid generation (124.7 mg/L and 82.7 mg/L), butyric acid (134.0 mg/L and 230.4 mg/L) and there wasn’t methane generation in the reactors. Microscopic analysis of biomass in anaerobic reactors showed the predominance of Gram positive rods and rods with endospores, whose morphology is characteristic of H2-generating bacteria, in both tests. These species were selected from the natural environment. In DGGE analysis performed difference were observed between populations from inoculum and in tests. This analysis confirmed that some species of bacteria were selected which remained under the conditions imposed on the experiment. The efficiency of the pre-treatment of inoculum and the imposition of pH 5.5 inhibited methane-producing microorganisms and the consumers of H2. Therefore, the experimental conditions imposed allowed the attainment of bacterial consortium of producer H2 taken from an environmental sample with concentration of xylose and glucose similar to the ones of the industrial effluents.

Estudo dos compostos voláteis da decomposição térmica dos anti-helmínticos Albendazol e Mebendazol

The albendazole and mebendazole drugs are benzimidazole derivatives and belong to the anthelmintic class. These drugs are particularly recommended for the treatment against worms present in the gastrointestinal tract of animals and humans, by acting directly on the worm metabolism. The need for thermally study drugs is related to all the parameters that these analyzes include: presence or absence of polymorphs, possible changes in the crystallinity of the drugs, as well as the quality control during the manufacturing process thereof. In this study the thermal behavior of anthelmintic albendazole and commercial mebendazole and its recrystallisation in organic solvents, such as acetic acid and formic acid in dimethylformamide to mebendazole, and albendazole were studied using TG-DSC techniques, TG-FTIR, FTIR and XRD. TG-DSC techniques were used so it could collect information about the thermal stability of the compounds steps for thermal decomposition process and also prove its melting temperature. For recrystallization of drugs in organic solvents, the TG-DSC curves were analyzed to compare and determine that the occurrence of polymorphs. The coupled TG-FTIR technique allowed the analysis of volatile products which were released during the thermal decomposition of the commercial mebendazole. The absorption spectroscopy in the infrared region was performed to mebendazole, and albendazole in order to show the difference in functional groups of both, comparing the spectra with commercial drugs and see if there was recrystallized changes in the absorption band where the drug was recrystallized or when heated. The diffraction technique by powder X-ray method was used for comparison of the crystal structures of commercial drugs and recrystallization in organic solvents to identify changes in crystallinity both, which might suggest the formation of polymorphs

Análise químico-farmacêutica do ácido fusídico em formulações de creme

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

Efeito das toxinas urêmicas guanidina e ácido guanidinoácetico sobre o metabolismo oxidativo e apoptose em neutrófilos de cães

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