330 resultados para ESPECTROFOTOMETRIA


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This study evaluated the effect of daily chromium supplementation at growing doses on serum Cr levels in cattle. Sixty Nellore heifers 2 to 5 years old were randomly assigned to one of four groups (15 heifers/group) fed non-fertilized Brachiaria decumbens pasture. In the control group (Gc), the heifers received a mineral mixture without Cr. In the other groups, heifers received 0.59, 1.19 or 2.38 mg Cr+3/animal/day, groups G8,5, G17 and G34, respectively. Blood samples were collected on days 0, 30 and 60. Serum concentration of chromium was determined by graphite furnace atomic absorption spectrophotometer. The chromium source used was the chromium yeast. The results do not support any significant difference (p>0.05) among serum chromium levels of heifers in groups Gc, G8,5, G17 and G34 at a same observation day. Only effect of supplementation time was detected in group G34. In this group there was significant increase (p<0,05) in the concentration serum chromium 60 days after the beginning of the experiment. Concluded Cr yeast can be used as the source of this mineral element for animals and supplementation with 2.38 mg/ cattle/day was the dose that most increased the serum concentration of Cr in Nellore cattle during the experimental period.

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The Asian rust currently is the main disease of soybean culture, having as characteristics the difficult control, by start at the bottom of plants where penetration of the droplets is harder. The fine droplets has been used with the intention of improve the penetration and increase efficiency of agrochemicals, but that are losses by drift easily. New products have been developed to increase deposition of the drops at targets. The aim of this work was evaluate the TA- 35 capacity to improving the deposition of fungicides spray solution with or without mineral oil by aerial and ground applications. Was used a factorial 3x2, three spray solutions composed by Priori Xtra (concentrated suspension of azoxystrobin 200 g L-1 + cyproconazole 80 g L-1 ) mixed with adjuvants, Nimbus (emulsifiable concentrate containing aliphatic hydrocarbons 428 g L-1 ) and TA-35 (soluble concentrate containing sodium lauryl ether sulfate, surfactants, sequestering agents and emulsifiers), in aerial and ground applications. In ground applications was used 50 L ha-1 , TXA 8002 VS spray nozzles and on aerials was used 15 L ha-1 , Turboaero atomizer, both applying fine droplets. Was utilized the Brilliant Blue (FD & C n. 1) tracer to determine the deposits. There were used glass slides as targets to collect spray droplets. After to extract the tracer of the targets using distilled water, the samples were analyzed by spectrophotometry, thereby was possible quantify the tracer deposited on each glass slide. A study to evaluate possible losses of the tracer by degradation or retention also was done. The comparative analysis of treatments was done by statistical method "Confidence Interval for Differences Between the Averages" with 95% of confidence degree (IC95%). There was degradation or retention of the tracer between the processes of application of the droplets and the processing of the samples. The deposition averages with the presence of TA-35 were greatest for both sprayers however, there were not significant differences among the treatments. The viability of TA-35 use may consider other parameters or complementary studies.

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The aim of this study was to build and validate a low cost reduced-scale wind tunnel for drift evaluation on pesticide application technology. The work was carried out at the NEMPA - Núcleo de Ensaio de Máquinas e Pneus Agroflorestais (NEMPA), FCA/UNESP, Departamento de Engenharia Rural, Botucatu/SP, Brazil. The wind tunnel main characteristics were an open circuit and a closed working section with a fan blowing air into the tunnel. Screens were fitted downstream after the fan in order to stabilize the air flow on the working section. The tunnel was built with 3.0 mm eucalyptus hardboard, with a total length of 4.8 m and a squared section of 0.56 m. The air flow was provided by a 180 W axial fan. The system was adjusted and calibrated to provide a laminar and stable flow at 2.0 m s-1. Validation studies were carried out by using a Teejet XR 8003 flat fan nozzle at 200 kPa (medium droplets) to apply a spray solutions containing water plus a food dye (Blue FDC) at 0,6% m v-1 mixed with two adjuvants: a polymer based anti drift formulation at 0,06% m v-1 and a sodium lauryl ether sulfate based surfactant at 0,2% v v-1. After a 10-second application the drift was collected on nylon strips transversally fixed along the tunnel at different distances from the nozzle and different high from the bottom part of the tunnel. Drift deposits were evaluated by spectrophotometry. The wind tunnel had low levels of turbulence and high repeatability of the data, which means that the flow was uniform and able to be used for carrying out measures to estimate drift. The validation results showed that the tunnel was effective to enable comparative drift measurements on the spray solution used in this work making possible the evaluation of drift risk potential under those spray technologies. The use of an adjuvant based on a polymer reduced the amount of drift from the nozzle compared to the surfactant.

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The aim of this work was to evaluate the effect of the addition of different surfactants in physical and chemical properties of spray solutions, droplets spectra and drift potential on agricultural spraying. The surfactants and concentrations (v v-1) were: Haiten (0.1%), Antideriva and Intec (0.05% and 0.1%). The following characteristics were analyzed: surface tension, viscosity, density and electric conductivity. The droplet size spectrum was determined by a laser particle analyzer (Mastersizer S®, version 2.15) including measurements of volume medium diameter (VMD), the percent of droplets below 50 and 100 μm (V50 e V100) and index span. In order to estimate the drift potential, a series of wind tunnel tests were performed with a Teejet XR 8003 flat fan nozzle at 200 kPa (medium droplets) used to apply the spray solutions containing water, the adjuvants and a food color dye (Brilliant blue FD & C no 1) at 0,6% m v-1. The drift was collected on nylon strips transversally fixed along the tunnel at different distances from the nozzle and different high from the bottom part of the tunnel. Drift deposits were evaluated by spectrophotometry. The results showed that the addition of adjuvants changed physical and chemical properties of spray solutions in different magnitudes according to the surfactant. Surfactants changed the droplet spectrum and drift potential, indicating that higher VMD and smaller V100 induced higher percentage of drift.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The objective of this study was to evaluate the effect of adding calcium ions and fluoride in the formulation of a whitening gel 35% hydrogen peroxide in its penetration through the dental structure, whitening efficacy and surface hardness of dental enamel. 80 teeth bovine incisors were used, which were obtained enamel and dentin disks of the buccal surface with 6mm diameter and 2mm thick (1 mm of enamel and dentin 1mm). The samples were divided into four groups stratified according to the protective substance / remineralizing added to the gel of hydrogen peroxide 35%: Group Ca - Calcium gluconate 0.5%; Group F - Sodium fluoride 0.2%; Group Ca + F - Calcium gluconate 0.5% and Sodium Fluoride 0.2%; Control group - no substance was added. The initial color of the samples and the hardness of the enamel were measured before the bleaching procedures. The specimens from each group were placed on a metallic support on which there was a simulated pulp chamber, which was filled with acetate buffer to collect and stabilize the penetrated peroxide. The respective bleaching treatments were applied 3 times, total of 30 minutes of application. The amount of peroxide which passed through the samples was determined by absorbance spectrophotometry. The hardness of the samples was measured immediately after bleaching. Next, the samples were immersed in artificial saliva for 7 days, after which the final color was evaluated. Data were statistically analyzed adopting a 5% significance level

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

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The objective of this study was to evaluate the effect of adding calcium ions and fluoride in the formulation of a whitening gel 35% hydrogen peroxide in its penetration through the dental structure, whitening efficacy and surface hardness of dental enamel. 80 teeth bovine incisors were used, which were obtained enamel and dentin disks of the buccal surface with 6mm diameter and 2mm thick (1 mm of enamel and dentin 1mm). The samples were divided into four groups stratified according to the protective substance / remineralizing added to the gel of hydrogen peroxide 35%: Group Ca - Calcium gluconate 0.5%; Group F - Sodium fluoride 0.2%; Group Ca + F - Calcium gluconate 0.5% and Sodium Fluoride 0.2%; Control group - no substance was added. The initial color of the samples and the hardness of the enamel were measured before the bleaching procedures. The specimens from each group were placed on a metallic support on which there was a simulated pulp chamber, which was filled with acetate buffer to collect and stabilize the penetrated peroxide. The respective bleaching treatments were applied 3 times, total of 30 minutes of application. The amount of peroxide which passed through the samples was determined by absorbance spectrophotometry. The hardness of the samples was measured immediately after bleaching. Next, the samples were immersed in artificial saliva for 7 days, after which the final color was evaluated. Data were statistically analyzed adopting a 5% significance level

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

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Dapsone use is frequently associated to hematological side effects such as methemoglobinemia and hemolytic anemia, which are related to N-hydroxylation mediated by the P450 enzyme system. The aim of the present study was to evaluate the influence of L-arginine supplementation, a precursor for the synthesis of nitric oxide, as single or multiple dose regimens on dapsone-induced methemoglobinemia. Male Wistar rats were treated with L-arginine at 5, 15, 30, 60 and 180 mg/kg doses (p.o., gavage) in single or multiple dose regimens 2 hours prior to dapsone administration (40 mg/kg, i.p.). The effect of the nitric oxide synthase inhibitor L-NAME was investigated by treatment with multiple doses of 30 mg/kg (p.o., gavage) 2 hours before dapsone administration. Blood samples were collected 2 hours after dapsone administration. Erythrocytic methemoglobin levels were assayed by spectrophotometry. The results showed that multiple dose supplementations with 5 and 15 mg/kg L-arginine reduced dapsone-induced methemoglobin levels. This effect is mediated by nitric oxide formation, since the reduction in methemoglobin levels by L-arginine is blocked by simultaneous administration with L-NAME, a nitric oxide synthase inhibitor.

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INTRODUÇÃO: O fígado é uma estrutura de elevada complexidade e é fundamental entender como determinadas substâncias podem afetar sua estrutura e suas funções. OBJETIVO: Analisar a influência da tibolona no metabolismo hepático por meio da avaliação de enzimas e metabólitos comumente utilizados em provas de função hepática. MÉTODOS: Foram utilizadas dez ratas Wistar, divididas em dois grupos: controle (n = 4) e tibolona (n = 6), em status de menopausa cirúrgica. A tibolona (1 mg) foi administrada diariamente por gavagem durante 20 semanas, com avaliação periódica do peso corporal. Após sedação, efetuou-se coleta de sangue para avaliação bioquímica de albumina (Alb) sérica, fosfatase alcalina (FA), transaminases (aspartato aminotransferase e alanina aminotransferase [AST/ALT]), gama-glutamiltranspeptidase (GGT) e glicose, mediante espectrofotometria. O músculo esquelético da coxa foi avaliado por histomorfometria em cortes histológicos corados com hematoxilina e eosina (HE). RESULTADOS: Os animais do grupo tibolona mostraram menor peso corporal, alterações musculares esqueléticas e discretas alterações bioquímicas. Além disso, AST e FA estavam diminuídas e GGT estava mais elevada, porém sem significância estatística. A histomorfometria do músculo revelou uma tendência de menor volume celular nesse grupo. CONCLUSÃO: A tibolona, administrada em alta dose e por tempo prolongado, não interfere de forma significativa nas funções metabólicas e de síntese hepáticas, bem como na permeabilidade da membrana celular, entretanto parece modular a expressão genômica da GGT. A tibolona apresenta influência sistêmica associada a menor peso e diminuição da massa muscular e aumento significativo no peso relativo do fígado, além de alteração da glicogenólise hepática e muscular, da gliconeogênese hepática e dos níveis de glicose circulante.

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The viability and interpretation of techniques for the evaluation of immunocompetence of animals in their natural environment has been largely debated. One of these methods is based on testing the antimicrobial capacity of the blood and/or plasma in vitro, which could rapidly and effectively assess the immunological conditions of natural populations. We tested the applicability of the antimicrobial capacity of plasma (ACP) assay in anuran amphibians from the Atlantic Forest. The assay was performed by measuring both the turbidity (in a spectrophotometer) and the colony forming units (CFU) of the remaining bacteria (Escherichia coli) following exposure to amphibian plasma. Although both assays were correlated, the ACP assay by spectrophotometry showed 10 times lower intra-assay variation. We also found interspecific variation in ACP, as well as the maintenance of ACP values in males from the same population, collected in different breeding seasons. Thus, the estimation of ACP by spectrophotometry provides a convenient and accurate method for evaluating innate immunocompetence in comparative and ecophysiological studies of anuran amphibians.