Electrocatalytic behavior of glassy carbon electrodes modified with multiwalled carbon nanotubes and cobalt phthalocyanine for selective analysis of dopamine in presence of ascorbic acid

This work describes the development, electrochemical characterization and utilization of a cobalt phthalocyanine modified carbon nanotube electrode for the quantitative determination of dopamine in 0.2 mol L-1 phosphate buffer contaminated with high concentration of ascorbic acid. The electrode surface was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy which showed a modified surface presenting a charge transfer resistance of 500 Omega, against the 16.46 k Omega value found for the bare glassy carbon surface. A pseudo rate constant value of 5.4 x 10(-4) cm s(-1) for dopamine oxidation was calculated. Voltammetric experiments showed a shift of the peak potential of DA oxidation to less positive value at 390 mV as compared with that of a bare GC electrode at 570 mV. The electrochemical determination of dopamine, in presence of ascorbic acid in concentrations up to 0.1 mol L-1 by differential pulse voltarnmetry, yielded a detection limit as low as 2.56 x 10(-7) mol L-1.

Determination of carbaryl in tomato ""in natura"" using an amperometric biosensor based on the inhibition of acetylcholinesterase activity

This work reports the utilization of two methodologies for carbaryl determination in tomatoes. The measurements were carried out using an amperometric biosensor technique based on the inhibition of acetylcholinesterase activity due to carbaryl adsorption and a HPLC procedure. The electrochemical experiments were performed in 0.1 mol L-1 phosphate buffer solutions at pH 7.4 with an incubation time of 8 min. The analytical curve obtained in pure solutions showed excellent linearity in the 5.0 x 10(-5) to 75 x 10(-5) mol L-1 range, with the limit of detection at 0.4 x 10(-3) gL(-1). The application of such a methodology in tomato samples involved solely liquidising the samples, which were spiked with 6.0 x 10(-6) and 5.0 x 10(-5) mol L-1 carbaryl. Recovery in such samples presented values of 99.0 and 92.4%, respectively. In order to obtain a comparison, HPLC experiments were also conducted under similar conditions. However, the tomato samples have to be manipulated by an extraction procedure (MSPD), which yielded much lower recovery values (78.3 and 84.8%, respectively). On the other hand, the detection limit obtained was much lower than that for the biosensor, i.e., 3.2 x 10(-6) g L-1. Finally, the biosensor methodology was employed to analyze carbaryl directly inside the tomato, without any previous manipulation. In this case, the biosensor was immersed in the tomato pulp, which had previously been spiked with the pesticide for 8 min, removed and inserted in the electrochemical cell. A recovery of 83.4% was obtained, showing very low interference of the matrix constituents. (C) 2007 Elsevier B.V. All rights reserved.

Determination of epinephrine in urine using multi-walled carbon nanotube modified with cobalt phthalocyanine in a paraffin composite electrode

This paper describes the development, electrochemical characterization and utilization of a cobalt phthalocyanine (CoPc), modified multi-walled carbon nanotube (MWCNT), and paraffin composite electrode for the quantitative determination of epinephrine (EP) in human urine samples. The electrochemical profile of the proposed composite electrode was analyzed by differential pulse voltammetry (DPV) that showed a shift of the oxidation peak potential of EP at 175 mV to less positive value, compared with a paraffin/graphite composite electrode without CoPc. DPV experiments in PBS at pH 6.0 were performed to determine EP without any previous step of extraction, clean-up, and derivatization, in the range from 1.33 to 5.50 mu mol L(-1), with a detection limit of 15.6 nmol L(-1) (2.86) of EP in electrolyte prepared with purified water. The lifetime of the proposed sensors was at least over 1000 determinations with 1.7 and 3.1 repeatability and reproducibility relative standard deviations, respectively. Human urine samples without any purification step were successfully analyzed under the standard addition method using paraffin/MWCNT/CoPc composite electrode. (C) 2010 Elsevier B.V. All rights reserved.

Structural studies of prephenate dehydratase from Mycobacterium tuberculosis H37Rv by SAXS, ultracentrifugation, and computational analysis

Tuberculosis (TB) is one of the most common infectious diseases known to man and responsible for millions of human deaths in the world. The increasing incidence of TB in developing countries, the proliferation of multidrug resistant strains, and the absence of resources for treatment have highlighted the need of developing new drugs against TB. The shikimate pathway leads to the biosynthesis of chorismate, a precursor of aromatic amino acids. This pathway is absent from mammals and shown to be essential for the survival of Mycobacterium tuberculosis, the causative agent of TB. Accordingly, enzymes of aromatic amino acid biosynthesis pathway represent promising targets for structure-based drug design. The first reaction in phenylalanine biosynthesis involves the conversion of chorismate to prephenate, catalyzed by chorismate mutase. The second reaction is catalyzed by prephenate dehydratase (PDT) and involves decarboxylation and dehydratation of prephenate to form phenylpyruvate, the precursor of phenylalanine. Here, we describe utilization of different techniques to infer the structure of M. tuberculosis PDT (MtbPDT) in solution. Small angle X-ray scattering and ultracentrifugation analysis showed that the protein oligomeric state is a tetramer and MtbPDT is a flat disk protein. Bioinformatics tools were used to infer the structure of MtbPDT A molecular model for MtbPDT is presented and molecular dynamics simulations indicate that MtbPDT i.s stable. Experimental and molecular modeling results were in agreement and provide evidence for a tetrameric state of MtbPDT in solution.

The value of a saved tree : The lifecycle of CO2-emissions associated with the combination of printing paper and electricity production of wood in the U.S. and Sweden

The pulp- and paper production is a very energy intensive industry sector. Both Sweden and the U.S. are major pulpandpaper producers. This report examines the energy and the CO2-emission connected with the pulp- and paperindustry for the two countries from a lifecycle perspective.New technologies make it possible to increase the electricity production in the integrated pulp- andpaper mill through black liquor gasification and a combined cycle (BLGCC). That way, the mill canproduce excess electricity, which can be sold and replace electricity produced in power plants. In thisprocess the by-products that are formed at the pulp-making process is used as fuel to produce electricity.In pulp- and paper mills today the technology for generating energy from the by-product in aTomlinson boiler is not as efficient as it could be compared to the BLGCC technology. Scenarios havebeen designed to investigate the results from using the BLGCC technique using a life cycle analysis.Two scenarios are being represented by a 1994 mill in the U.S. and a 1994 mill in Sweden.The scenariosare based on the average energy intensity of pulp- and paper mills as operating in 1994 in the U.S.and Sweden respectively. The two other scenarios are constituted by a »reference mill« in the U.S. andSweden using state-of-the-art technology. We investigate the impact of varying recycling rates and totalenergy use and CO2-emissions from the production of printing and writing paper. To economize withthe wood and that way save trees, we can use the trees that are replaced by recycling in a biomassgasification combined cycle (BIGCC) to produce electricity in a power station. This produces extra electricitywith a lower CO2 intensity than electricity generated by, for example, coal-fired power plants.The lifecycle analysis in this thesis also includes the use of waste treatment in the paper lifecycle. Both Sweden and theU.S. are countries that recycle paper. Still there is a lot of paper waste, this paper is a part of the countries municipalsolid waste (MSW). A lot of the MSW is landfilled, but parts of it are incinerated to extract electricity. The thesis hasdesigned special scenarios for the use of MSW in the lifecycle analysis.This report is studying and comparing two different countries and two different efficiencies on theBLGCC in four different scenarios. This gives a wide survey and points to essential parameters to specificallyreflect on, when making assumptions in a lifecycle analysis. The report shows that there arethree key parameters that have to be carefully considered when making a lifecycle analysis of wood inan energy and CO2-emission perspective in the pulp- and paper mill in the U.S. and in Sweden. First,there is the energy efficiency in the pulp- and paper mill, then the efficiency of the BLGCC and last theCO2 intensity of the electricity displaced by BIGCC or BLGCC generatedelectricity. It also show that with the current technology that we havetoday, it is possible to produce CO2 free paper with a waste paper amountup to 30%. The thesis discusses the system boundaries and the assumptions.Further and more detailed research, including amongst others thesystem boundaries and forestry, is recommended for more specificanswers.

Exploratory study of corporate social responsibility: blogs as a communication tool to enhance company-stakeholders relationships

O conceito de responsabilidade social corporativa (RSE) evoluiu gradualmente do objetivo de satisfazer as expectativas dos acionistas para o cumprimento das expectativas das partes interessadas. Tornou-se um conceito amplamente aceitado e promovido como as empresas enfrentam maiores pressões de atores internos e externos para cumprir objetivos sociais maiores. Assim, elas cada vez mais comunicam sobre os esforços de responsabilidade social delas, a fim de fomentar a confiança e o envolvimento dos stakeholders. Mas o aumento da cidadania global e as novas tecnologias de informação e de comunicação – como as mídias sociaias – está criando uma paisagem desafiador para a comunicação RSE, se traduzindo em escrutínio e ceticismo do público. No entanto, também está criando novas oportunidades para as empresas compartilhar e interagir com as partes interessadas. O estudo analisa especificamente como os blogs corporativos dedicados à comunicação RSE conseguem melhorar as relações entre as empresas e as partes interessadas. Esta pesquisa exploratória da estrutura e das mensagens de 9 blogs corporativos, é baseada em um quadro de análise sobre comunicação RSE em plataformas de mídias sociais desenvolvido por Gomez e Chalmeta (2013). O quadro está melhorado e adaptado para blogs graças à literatura sobre comunicação RSE, mídias sociais e blogs corporativos. Os resultados demonstram que o uso de características de blogs como apresentação, conteúdo e interatividade, é diversificado e reflete estratégias diferentes de comunicação RSE. Blogs permitem às empresas aumentar a visibilidade da comunicação RSE, melhorar a credibilidade e a legitimidade dos esforços de responsabilidade social, e também trazer discussões com os stakeholders. No entanto, demonstramos que as características e recursos dos blogs raramente são totalmente desenvolvidos, sugerindo avenidas para a melhoria no campo da comunicação nas mídias sociais. Especificamente, o uso da interatividade para criar relações baseadas em diálogo entre empresas e stakeholders está até atrasado em relação à extensão das oportunidades oferecidas pelos blogs. Além disso, o grau de utilização das ferramentas de blogs determina a eficácia da comunicação de RSE 2.0 das empresas na criação de relações empresa-stakeholder.

Is child labor harmful? the impact of working as a child on adult earnings

This paper explores the question: is working as young laborer harmful to an individual in terms of adult outcomes in income? This question is explored through the utilization of a unique set of instruments that control for the decision to work as a child and the decision of how much schooling to acquire. These instruments are combined with two large household survey data sets from Brazil that include retrospective information on the child labor and schooling of working-age adults: the 1988 and 1996 PNAD. Estimations of the reduced form earnings model are performed first by using OLS without controlling for the potential endogeneity of child labor and schooling, and then by using a GMM estimation of instrumental variables models that include the set of instruments for child labor and schooling. The findings of the empirical investigations show that child labor has large negative impact on adult earnings for both male and female children even when controlling for schooling. In addition, the negative impact of starting to work as a child reverses at around age 14. Finally, different child labor activities are examined to determine if some are beneficial while others harmful with the finding that working in agriculture as a child appears to have no negative impact over and above the loss of education.

Estudo da incorporação de cascalho proveniente da perfuração de poços de petróleo em formulações para tijolos de solo-cimento

The present work is to study the characteristics and technological properties of soil-cement bricks made from binary and ternary mixtures of Portland cement, sand, water, with or without addition of gravel from the drilling of oil wells, which could be used by industry, aiming to improve its performance and reduce cost by using the residue and, consequently, increasing its useful life. The soil-cement bricks are one of the alternatives to masonry construction. These elements, after a short curing period, provide compressive strength similar to that of solid bricks and ceramic blocks, and the higher the resistance the higher the amount of cement used. We used the soil from the city of São José do Mipibu / RN, the banks of the River Baldun, cement CPIIZ-32 and residue of drill cuttings from oil wells drilling onshore wells in the town of Mossley, RN, provided Petrobras. To determine the optimum mix, we studied the inclusion of different residues (100%, 80%, 70%, 60% and 50%) where 15 bodies were made of the test piece. The assessment was made of bricks made from simple compression tests, mass loss by immersion and water absorption. The experimental results proved the efficiency and high utilization of the waste from the drilling of oil wells, making the brick-cement-soil residue with a higher strength and lower water absorption. The best result in terms of mechanical strength and water absorption for the ternary mixture was 10% soil, 14% cement and 80% residue. In terms of binary mixtures, we obtained the best result for the mix-cement residue, which was 14% cement incorporated in the residue

Desenvolvimento de argamassa para restauração utilizando resíduo do polimento do porcelanato

The coatings mortars are essential elements of building structures because they execute an important role in protecting walls and are particularly exposed to aggressive action responsible for its degradation over time. The importance of wall coverings has been the subject of discussion and analysis in the conservation and rehabilitation of old buildings. Are sometimes removed and replaced with inappropriate solutions of constructive point of view or architecture. The most commonly used coatings on walls of old buildings is based on traditional hydraulic lime mortars. The present study aims at the formulation of new lime- based mortars and aerial fine aggregate, in order to contribute to a better field of conservation and restoration mortar coating of old buildings. Residue was used for polishing porcelain as fine aggregate, replacing the aggregate (sand), in percentages 05-30% by mass. We conducted a thorough evaluation of the mortar properties in fresh and hardened state by comparing the performance of the same with a reference mortar. The residue used was characterized as the density, bulk density, and particle size laser, scanning electron microscopy, X-ray diffraction and X-ray fluorescence. Formulations were produced 7, 6 with residue and one commonly used formulation, which served as a reference. In the formulations of lime mortars air (hydrated lime powder CH-I) has been adopted a stroke volume (1:3) with constant binder, was varied and the water / binder and aggregate and waste. For evaluation of mortars fresh, proceeded to consistency analysis, specific gravity, water retention and air content embedded. In the hardened state assays were performed in specific gravity, water retention, modulus of elasticity, tensile strength in bending, compressive strength, water absorption by capillary action, adhesion, tensile strength, resistance to shrinkage and salts by of crystallization trials with resources chloride solution, nitrate and sulfate all sodium in prismatic at 90 days of age, in addition to the micro structural analysis of mortars. Based on the results we can see that the mortar formulated with 10% content of waste and the reference free retraction feature more stable closer to neutrality. The composition of 10% was obtained better performance against the action of the salt crystallization. The mortar with 15% residue obtained better density, lower air content embedded and high capacity for water retention developing good workability. The replacement of 20% of waste generates a satisfactory utilization of resistance to compression, flexion and traction grip the base. And, finally, it can be seen that the mortar with 10, 15 and 20% residual show, in principle, good suitability as coatings, thus enabling a final result consistent with durability, workability and aesthetics developing therefore a material with better performance to repair or replace existing mortars in old buildings

Digestibility and performance of pacu (Piaractus mesopotamicus) juveniles - fed diets containing different protein, lipid and carbohydrate levels

Due to lack of information on the use of non-protein energy sources in diets for pacu (Piaractus mesopotamicus), a 2 x 2 x 3 factorial experiment was conducted to evaluate the performance and digestibility of 12 diets containing approximately two crude protein (CP; 220 and 250 g kg(-1)), two lipid (40 and 80 g kg(-1)) and three carbohydrate levels (410, 460 and 500 g kg(-1)). The pacu juveniles-fed diets containing 220 g kg(-1) CP did not respond (P > 0.05) to increased dietary lipid and carbohydrate levels, but the fish-fed diets containing 250 g kg(-1) CP showed a better feed conversion ratio. There were interactions in weight gain (WG), specific growth rate (SGR), crude protein intake (CPI) and feed conversion rate (FCR) dependent on dietary carbohydrate and lipid levels, showing positive effects of increasing carbohydrate levels only for fish-fed diets containing 80 g kg(-1) lipid level. However, when the diets contained 40 g kg(-1) lipid, the best energy productive value (EPV) results were obtained at 460 g kg(-1) carbohydrate. A higher usage of lipids (80 g kg(-1)) reduced CPI and was detrimental to protein [apparent digestibility coefficient (ADC)(CP)] and energy (ADC(GE)), but did not affect growth. The ADC(GE) improved proportionally as dietary carbohydrate levels increased (P < 0.05), increasing the concentration of digestible energy. In addition, the WG, CPI, ADC(GE) results showed best use of the energy from carbohydrates when dietary protein level was 250 g kg(-1) CP. The utilization of 250 g kg(-1) CP in feeds for juvenile pacu for optimal growth is suggested. Therefore, the optimum dietary lipid and carbohydrate levels depend on their combinations. It can be stated that pacu uses carbohydrates as effectively as lipids in the maximization of protein usage, as long as it is not lower than 250 g kg(-1) CP or approximately 230 g kg(-1) digestible protein.

Growth performance and energetic metabolism of pacu, Piaractus mesopotamicus (Holmberg, 1887), fed diets supplemented with ammonium metavanadate

Vanadium compounds mimic most of the metabolic effects of insulin, suggesting that it might be useful to improve utilization of dietary carbohydrate. This work evaluated the effect of dietary ammonium metavanadate (H(4)NO(3)V) on the growth performance and energy metabolism of pacu, an omnivorous South America characin. Two hundred and eighty-eight fish were distributed into four blocks according to the body weight (21.8 +/- 1.7, 28.5 +/- 2.0, 28.4 +/- 1.9, 35.7 +/- 1.9 g), stocked in 24 plastic tanks and fed twice daily with isonitrogenous and isoenergetic diets containing six levels of H(4)NO(3)V (0, 10, 50, 100, 300 and 1000 mg kg(-1)) for 60 days. Increasing levels of dietary ammonium metavanadate did not improve growth (P > 0.05), and the highest level of inclusion (1000 mg kg(-1)) reduced performance (P < 0.05). Blood glucose levels decreased (P < 0.05) in fish fed 300 and 1000 mg kg(-1) H(4)NO(3)V, but no differences were observed in other blood metabolites. A slight increase in muscle lipid content was observed in fish fed a diet containing 300 mg kg(-1) H(4)NO(3)V. Based on the results of this study, there is no benefit in supplementing pacu diets with metavanadate.

Methodology for fast evaluation of Bacillus thuringiensis crystal protein content

O desenvolvimento da produção e uso do Bacillus thuringiensis no Brasil em escala comercial enfrenta certas dificuldades, entre elas o estabelecimento de metodologias para a quantificação de produtos tóxicos a serem comercializados. Atualmente, a quantidade de toxinas é expressa como porcentagem do total de proteínas presentes em amostras em consideração. Tal metodologia, entretanto, não mede a quantidade real de uma determinada proteína presente em um produto qualquer, além do fato de diferentes linhagens bacterianas possuírem diferentes genes codificadores para endotoxinas e mesmo para b-toxina. Desde que os diferentes tipos de toxinas apresentam diferentes características antigências, este trabalho tem como objetivo a utilização de técnicas imunológicas para quantificar específicamente o conteúdo de proteína cristal presente em diferentes amostras. A proteína cristal produzida pela subespécie B. thuringiensis var. israelensis foi purificada por ultracentrifugação e utilizada para imunizar coelhas e produzir soros hiperimunes. Tais soros foram posteriormente usados para avaliar o nível de proteína cristal em bioinseticidas comerciais e em culturas de laboratório desta bactéria utilizando-se a técnica do imunodot. Os resultados foram obtidos por comparação de reações com concentrações conhecidas de proteína cristal permitindo assim avaliar com segurança os níveis desta proteína em várias preparações.

Protein levels and environmental temperature effects on carcass characteristics, performance, and nitrogen excretion of broiler chickens from 7 to 21 days of age

This trial was conducted to evaluate the utilization of low-protein diets formulated based on the ideal protein concept for broiler chickens from 7 to 21 days of age reared at different environmental temperatures. Nine hundred male Cobb-500® chickens were used. At day seven chicks were distributed according to a completely randomized design in a 3 x 3 factorial with four replications of 25 birds each. It was used three crude protein levels in the diet (21.5; 20.0 and 18.5%) and three environmental temperatures (low, thermoneutral and high). The performance, carcass characteristics (yield and chemical composition), and nitrogen ingestion and excretion were assessed. There was no significant interaction among the factors for the evaluated variables. Environmental temperatures affected differently chicken performance. High environmental temperature resulted in lower weight gain and higher wing fat percentage, whereas cold temperature resulted in higher feed conversion. on the other hand, low-protein diets decreased weight gain, breast yield, nitrogen excretion and influenced breast and wings chemical composition. Birds reared at high environmental temperature showed lower nitrogen intake and excretion. The results showed that the decrease in protein levels from 7 to 21 days of age contributed to lower nitrogen excretion in broiler chickens, but impaired performance and carcass characteristics independent of rearing temperature.

Molecular differentiation of Salmonella Gallinarum and Salmonella Pullorum by RFLP of fliC gene from Brazilian isolates

Although Salmonella Pullorum and Salmonella Gallinarum cause different diseases in poultry, they are very similar. Both are non-motile and present the same somatic antigenic structure. They are differentiated by biochemical tests. Certain atypical strains are very difficult to distinguish. They do not produce the expected results when dulcitol and ornithine descarxboxylase tests are performed. Therefore, additional tests could be helpful. Many studies have chose the part I of the gene that encodes flagellin (fliC) to differentiate serotypes. Most Salmonella strains have two structural genes (fliC and fliB) that encode flagellins. Non-motile strains generally present these structural genes, but are not able to build a functional flagellum. It was demonstrated that enzymatic restriction of the amplified fliC gene using Hinp1I enzyme can differentiate SG from SP. In the present study, this method was adopted to analyze 14 SP and 22 SG strains, including some strains with atypical results in biochemical tests assessing the utilization of dulcitol and ornithine. The results showed that all SG strains were broken by the enzyme, whereas the 14 SP strains were not.

A classification of Pepper yellow mosaic virus isolates into pathotypes

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