963 resultados para Age, lower confidence level


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A novel, simple, rapid and eco-friendly method based on dispersive liquid-liquid microextraction using a bromosolvent was developed to determine six estrogenic mycotoxins (zearalenone, zearalanone, alpha-zearalanol, beta-zearalanol, alpha-zearalenol and beta-zearalenol) in water samples by liquid chromatography-electrospray ionization tandem mass spectrometry in the negative mode (LC-ESI-MS/MS). The optimal conditions for this method include the use of 100 mu L bromocyclohexane as an extraction solvent (using a non-dispersion solvent), 10 mL of aqueous sample (adjusted to pH 4), a vortex extraction time of 2 min, centrifugation for 10 min at 3500 rpm and no ionic strength adjustment. The calibration function was linear and was verified by applying the Mandel fitting test with a 95% confidence level. No matrix effect was observed. According to the relative standard deviations (RSDs), the precision was better than 13% for the repeatability and intermediate precision. The average recoveries of the spiked compounds ranged from 81 to 118%. The method limits of detection (LOD) and quantification (LOQ) considering a 125-fold pre-concentration step were 4-20 and 8-40 ng L-1, respectively. Next, the method was applied to the analysis of the environmental aqueous samples, demonstrating the presence of beta-zearalanol and zearalanone in the river water samples. (C) 2015 Elsevier B.V. All rights reserved.

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

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The Spanish region of Campos de Hellin (Albacete) is characterized by a wide range of olive varieties (Arbequina, Benizal, Cornicabra, Cuquillo, Injerta, Manzanilla Local, Manzanilla de Sevilla, Negrilla, Picual), which provides different physicochemical and sensory characteristics to the oils. Thus, the knowledge of these characteristics may help develop more balanced oils. Monovarietal virgin olive oils from the different varieties grown in this area were characterized from the physicochemical and sensory points of view during four consecutive years. Clear differences among the varieties were found when principal component analysis was applied to the data from the studied parameters. The varieties were grouped according to their oleic and linoleic acid content, oxidative stability, and campesterol and total sterols content. The differences were significant with a 95% confidence level. The variety effect on the oil characteristics was stronger than the effect of the crop year. Practical applications: Chemical and sensory characteristics of monovarietal virgin olive oils play an important role in the elaboration of blends. In olive-growing regions where there is more than one variety cultivated, the characterization of monovarietal oils could increase the value of the olive oil produced due to the development of more balanced oils tailored to the preferences of consumers. This work shows that the chemical and sensory differences between varieties make possible the elaboration of a new range of virgin olive oils. This could encourage the development and marketing of quality oils, and thus increase the competitiveness of the mills in the oil market.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The objective of this study was to assess penetration of adhesive material in enamel bleached with 35% hydrogen peroxide using optical polarized light microscopy. Extracted human teeth were randomly assigned to 5 groups, each representing a specific time interval between bleaching and the application of an adhesive material. They were designated as: (TC) the control group-restorations in unbleached teeth; (T0) comprising restorations carried out immediately after bleaching; (T7) comprising restorations 7 days after bleaching; (T14) comprising restorations 14 days after bleaching; and (T21) comprising restorations 21 days after bleaching. Length of resin tags was measured with an Axiophot photomicroscope at a x 400 magnification, and the results subjected to an ANOVA for a comparison between groups, with a p value of < 0.05. Differences between the groups were verified using a Tukey test at a confidence level of 5%. The specimens in the control group (TC) and experimental groups T7, T14 and T21 showed better penetration of adhesive material into enamel in comparison with experimental group T0. This suggests that a gap of at least 7 days should be left between bleaching enamel with 35% hydrogen peroxide and placing adhesive bonding agents and undertaking resin composite restoration work.

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Pós-graduação em Medicina Veterinária - FCAV

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A simple and fast method to determine Ca, K and Mg in a single aliquot of medicinal plants by HR-CS FAAS is proposed. The secondary lines for Ca (239.856 nm) and K (404.414 nm), and the alternate line measured at wing of the secondary line for Mg at (202.588 nm) allowed calibration within the 20 - 500 mg.L-1 Ca and K, and 1.0 - 80 mg.L-1 Mg. Twenty samples and three plant certified materials were analyzed. Results were in agreement at a 95% confidence level with reference values. Limits of detection were 2.4 mg.L-1 Ca, 1.9 mg.L-1 K and 0.3 mg.L-1 Mg. The RSD (n=12) were ≤ 5.1% and recoveries were between 83 and 108% for all analytes.

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This work describes instrumental strategies for the determination of Mn in a wide range concentration by high-resolution continuum source flame atomic absorption spectrometry technique (HR-CS F AAS) by means of different atomic lines (primary at 279.482 nm, secondary at 403.075 nm and alternative at 209.250 nm). These lines provided complementary concentration intervals, and large sample dilutions became unnecessary. The proposed method was applied to tap water, metal alloy certified material and foliar fertilizer. Accuracy for secondary line were evaluated by tests of significance (t Student test) with reference materials from the Institute of Technological Research of São Paulo, and the results were in agreement at the 95% confidence level. For primary and alternative lines, recovery is were in the 84-116% range and the RSD were 6.1% for all wavelengths. Analytical curves in the 0.1 - 2.0 mg L-1 (279.482 nm), 2.0 - 25 mg L-1 (403.075 nm), 25 - 500 mg L-1 (209.250 nm) intervals were obtained with linear correlation coefficient better than 0.9991. The detection limits were 3.3x10-3 mg L-1 (279.482 nm), 7.4 x 10-3 mg L-1 (403.075 nm), 3.9 mg L- 1 (209.250 nm). The found Mn concentrations were < 3.3x10-3 mg L-1 (tap water), 1.00 ± 0.04 (% m/m) (alloy IPT 25), 7235 ± 175 mg L-1 (foliar fertilizer 1), 4990 ± 132 mg L-1 (foliar fertilizer 2). A method was developed to detect interference of Fe in the Mn primary line (279.482 nm) using the ratio of absorbances of other lines of the triplet (279.827 nm and 280,108 nm).

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Most consumers consider the fat of chicken meat undesirable for a healthy diet, due to the high levels of saturated fatty acids and cholesterol. The purpose of this experiment was to investigate the influence of changes in dietary metabolizable energy level, associated with a proportional nutrient density variation, on broiler chickens performance and on the lipid composition of meat. Males and females Cobb 500 broilers were evaluated separately. Performance evaluation followed a completely randomized design with factorial 6x3 arrangement - six energy levels (2,800, 2,900, 3,000, 3,100, 3,200 and 3,300 kcal/kg) and three slaughter ages (42, 49 and 56 days). Response surface methodology was used to establish a mathematical model to explain live weight, feed intake and feed conversion behavior. Total lipids and cholesterol were determined in skinned breast meat and in thigh meat, with and without skin. For lipid composition analysis, a 3x3x2 factorial arrangement in a completely randomized design - three ration’s metabolizable energy levels (2,800, 3,000 and 3,300 kcal/kg), three slaughter ages (42, 49 and 56 days) and two sexes - was used. The reduction in the diet metabolizable energy up to close to 3,000 kcal/kg did not affect live weight but, below this value, the live weight decreased. Feed intake was lower when the dietary energy level was higher. Feed conversion was favored in a direct proportion to the increase of the energy level of the diet. The performance of all birds was within the range considered appropriate for the lineage. Breast meat had less total lipids and cholesterol than thigh meat. Thigh with skin had more than the double of total lipids of skinned thigh, but the cholesterol content did not differ with the removal of the skin, suggesting that cholesterol content is not associated with the subcutaneous fat. Intramuscular fat content was lower in the meat from birds fed diets with lower energy level. These results may help to define the most appropriate nutritional management. Despite the decrease in bird’s productive performance, the restriction of energy in broiler chickens feed may be a viable alternative, if the consumers are willing to pay more for meat with less fat.