55 resultados para Light water reactors
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Photoelectrochemical properties of FTO/BiVO4 electrode were investigated in different electrolytic solutions, potassium chloride (KCl) and sodium sulphate (Na2SO4), and under visible light irradiation condition. In order to accomplish that, an FTO/BiVO4 electrode was built by combining the solution combustion synthesis technique with the dip-coating deposition process. The morphology and structure of the BiVO4 electrode were investigated through X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Photoelectrochemical properties were analyzed through chronoamperometry measurements. Results have shown that the FTO/BiVO4 electrode presents higher electroactivity in the electrolyte Na2SO4, leading to better current stabilization, response time, and photoinduced current density, when compared to KCl electrolyte. Besides, this electrode shows excellent performance for methylene blue degradation under visible light irradiation condition. In Na2SO4, the electrode has shown higher degradation rate, 51 %, in contrast to 44 % in KCl, plus higher rate constant, 174 × 10-4 min-1 compared to 150 × 10-4 min-1 in KCl. Results presented in this communication leads to the indication of BiVO4 thin films as alternate materials to use in heterogeneous photoelectrocatalysis, more specifically in decontamination of surface water. © 2013 Springer-Verlag Berlin Heidelberg.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The aim of the present study was to evaluate the microtensile bond strength to dentin (ATBS) of two total-etching adhesives applied with delays of 1-30 s for curing. Fifty extracted molar teeth were used. Occlusal enamel was sectioned to expose flat dentin surface, which was further polished with 600-grit paper for smear layer standardization. The specimens were divided into two groups, G1: Single Bond total-etching adhesive (SB), and G2: Prime & Bond NT total-etching adhesive (PB). Each group was further divided into 5 subgroups according to the delayed light-cure initiation after the adhesive systems application (n=5): Subgroup 1s - 1 s; Subgroup 5s -5 s; Subgroup 10s - 10 s; Subgroup 20s - 20 s; Subgroup 30s - 30 s. Composite resin cones 5 mm height and 10 mm in diameter were fabricated. Specimens were stored in distilled water at 37 degrees C for 24 h and sectioned to obtain 1 x 1 mm(2) transversal specimens. Specimens were thermocycled and mu TBS was measured. Data were submitted to two-way ANOVA (AdhesiveXDelay time) and Tukey's test. The level of significance was set at 5%. The results in mean MPa(+/- SD) for interaction between adhesive and delay time were: PB/1s - 23.82 +/- 2.54a; SB/5s - 19.52 +/- 2.67b; PB/5s - 18.56 +/- 3.06bc; SB/1s - 15.49 +/- 2.69cd; SB/20s - 16.33 +/- 2.55d; SB/10s - 13.88 +/- 1.67d; PB/10s - 11.04 +/- 1.28e; PB/30s - 10.89 +/- 1.31e; PB/20s - 10.24 +/- 2.33e; SB/30s - 9.19 +/- 1.91e. It was concluded that light-cure initiation timing of total-etching adhesives interferes negatively with mu TBS to dentin. (C) 2014 Elsevier Ltd. All rights reserved.
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The knowledge of the physiology of Eucalyptus spp. germination may contribute significantly to the development of management and choice of suitability of the deployment areas. The aim was to evaluate the effects of water and salt stress on seed germination of Eucalyptus camaldulensis, E. citriodora, E. grandis, E. robusta and E. urophylla. The seeding was done with four replicates of 0.05 g of seeds in paper moistened with solutions at potentials of 0.0, -0.2, -0.4, and -0.8 MPa, induced with polyethylene glycol (PEG 6000) and NaCl. The germination test was in 25 degrees C in the presence of light. Were evaluated the first test score seven days after sowing, and weekly germination (normal seedlings) until 28 days. Were also calculated the germination speed index. Water stress causes a greater reduction in the rate of germination and accumulated germination of E. camaldulensis and E. citriodora seeds than salt stress, and the seeds of E. robusta are more adapted to germinate under salt stress moderate, between -0.2 and -0.4 MPa. Regardless of the substance used to induce stress, the threshold for germination was -0.8 MPa. The E. camaldulensis is the most sensitive specie to water stress and E. urophylla most sensitive to salt stress.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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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 investigate whether increased dietary water content and feeding frequency increased voluntary physical activity of young, lean adult female cats. A replicated 4 x 4 Latin square design with a 2 x 2 factorial treatment arrangement (feeding frequency and water content) was used. The 4 treatments consisted of 1 meal daily dry pet food without added water (1D; 12% moisture as is), 1 meal daily dry pet food with added water (1W; 70% total water content), 4 meals daily dry pet food without added water (4D; 12% moisture as is), and 4 meals daily dry pet food with added water (4W; 70% total water content). Eight healthy adult, lean, intact, young, female domestic shorthair cats were used in this experiment. Voluntary physical activity was evaluated using Actical activity monitors placed on collars and worn around the cats'necks for the last 7 d of each experimental period of 14 d. Food anticipatory activity (FAA) was calculated based on 2 h prior to feeding periods and expressed as a percentage of total daily voluntary physical activity. Increased feeding frequency (4 vs. 1 meal daily) resulted in greater average daily activity (P = 0.0147), activity during the light period (P = 0.0023), and light: dark activity ratio (P = 0.0002). In contrast, physical activity during the dark period was not altered by feeding frequency (P > 0.05). Cats fed 4 meals daily had increased afternoon FAA (P = 0.0029) compared with cats fed once daily. Dietary water content did not affect any measure of voluntary physical activity. Increased feeding frequency is an effective strategy to increase the voluntary physical activity of cats. Thus, it may assist in the prevention and management of obesity.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Phytochromes are red/far-red light photoreceptors that mediate a variety of photomorphogenic processes in plants, from germination to flowering. In addition, there is evidence that phytochromes are also part of the stress signalling response, especially in response to water deficit stress, which is the major abiotic factor limiting plant growth and crop productivity worldwide. In this study, we used the phyA (far red-insensitive; fri), phyB1 (temporary red-insensitive; tri) and phyB2 mutants of tomato (Solanum lycopersicum L.) to study the roles of these three phytochromes in drought stress responses. Compared to wild type (WT) plants grown under water-deficit stress conditions, the fri, tri, and phyB2 mutants did not exhibit altered dry weights, leaf areas, stomatal densities, or stomatal opening. The stomatal conductance of all three mutants was severely reduced under both fully-hydrated and water-deficit conditions. Although relative water contents did change after drought stress in each mutant, the most significant reduction in water potential during water stress was observed in the fri mutant. However, this mutant returned its water status to WT levels during rehydration. Although the phyB2 mutant lost more water from detached leaves during abscisic acid (ABA) treatment, phyB2 behaved like WT plants, indicating that this mutant was not insensitive to ABA. Overall, these results indicate that the phytochromes phyA, phyB1, and phyB2 modulate drought stress responses in tomato.