830 resultados para Synthesis of digital circuits
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Wurtzite-structured ZnS nanostructures have been synthesized by means of a microwave-solvothermal method at 140°C using three precursors (chloride, nitrate and acetate). Different techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy and photoluminescence (PL) measurements have been employed to characterize this material. The structure, surface morphology, chemical composition and optical properties were investigated as function of precursor. In order to complement experimental results, first principles calculations at DFT level were carried out in order to obtain the relative stability of the proposed intermediates along the formation mechanism. - See more at: http://www.eurekaselect.com/117237/article#sthash.GzvnCBTB.dpuf
Microwave-assisted hydrothermal synthesis of NiO-Ce1-XEuxO2-δ powders for fuel cell catalytic anodes
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CeO2-based materials doped with rare earth (TR +3) can be used as alternative to traditional NiO-YSZ anodes in solid oxide fuel cells as they have higher ionic conductivity and lower ohmic losses compared to YSZ. Moreover, they allow fuel cell operation at lower temperatures (500-800°C). In the anode composition, the concentration of NiO acting as catalyst in YSZ provides high electrical conductivity and high electrochemical activity of reactions, promoting internal reform in the cell. In this work, NiO - Ce1-xEuxO2-δ compounds (x = 0.1, 0.2 and 0.3) have been synthesized by microwave-assisted hydrothermal method. The materials were characterized by TG, XRD, TPR and SEM-FEG techniques. The refinement of data obtained by X-ray diffraction showed the presence of ceria doped with europium crystallized in a cubic phase with fluorite structure, in addition to the presence of NiO. The microwave-assisted hydrothermal method showed significant reduction in the average particle size and good mass control of phase compositions compared to other chemical synthesis techniques.
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Abstract. Biochar is the solid by-product of biomass pyrolysis. It is a promising soil conditioner and can be a material with high aggregate economic value, since its performance can improve plant’s nutrient utilization and reduce the usage of conventional fertilizers. Biochar can be used in the formulation of new types of fertilizers as polymeric microbeads. These microbeads can be enriched with biochar and nutrients in its matrix to form fertilizers of slow release of nutrients. Thus, as a promising agricultural material, it is important to assess the environmental hazards caused by the implementation of these microbeads. In this context, seeds were sown in a soil-less Petri dish with microbeads produced with biochar from sugarcane enriched with or without phosphate. The seeds germination and its vitality were evaluated by the first germination count (FGC) and the germination speed index (GSI). The short-term effects showed that the microbeads, in general, assessed by the means of FGC, GSI and mass gain showed the best performance, suggesting that the environment created by these materials provided the best chemical and physical interaction with the embryonic axes.
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The human dentition is naturally translucent, opalescent and fluorescent. Differences between the level of fluorescence of tooth structure and restorative materials may result in distinct metameric properties and consequently perceptible disparate esthetic behavior, which impairs the esthetic result of the restorations, frustrating both patients and staff. In this study, we evaluated the level of fluorescence of different composites (Durafill in tones A2 (Du), Charisma in tones A2 (Ch), Venus in tone A2 (Ve), Opallis enamel and dentin in tones A2 (OPD and OPE), Point 4 in tones A2 (P4), Z100 in tones A2 ( Z1), Z250 in tones A2 (Z2), Te-Econom in tones A2 (TE), Tetric Ceram in tones A2 (TC), Tetric Ceram N in tones A1, A2, A4 (TN1, TN2, TN4), Four seasons enamel and dentin in tones A2 (and 4SD 4SE), Empress Direct enamel and dentin in tones A2 (EDE and EDD) and Brilliant in tones A2 (Br)). Cylindrical specimens were prepared, coded and photographed in a standardized manner with a Canon EOS digital camera (400 ISO, 2.8 aperture and 1/ 30 speed), in a dark environment under the action of UV light (25 W). The images were analyzed with the software ScanWhite©-DMC/Darwin systems. The results showed statistical differences between the groups (p < 0.05), and between these same groups and the average fluorescence of the dentition of young (18 to 25 years) and adults (40 to 45 years) taken as control. It can be concluded that: Composites Z100, Z250 (3M ESPE) and Point 4 (Kerr) do not match with the fluorescence of human dentition and the fluorescence of the materials was found to be affected by their own tone.
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Population parameters of the shrimp Xiphopenaeus kroyeri (Heller, 1862) (sex ratio, length-frequency distributions (carapace length, CL), growth, lifespan, size of sexual maturity, spawning and recruitment) were analyzed in a long-term study from January 1998 through June 2003. The data on these parameters were collected and analyzed to test the hypothesis that the main period of juvenile recruitment in the bay coincides with the period of fishery closures currently designated by the Brazilian Institute of Environment and Renewable Natural Resources. Monthly collections were conducted along the southeastern Brazilian coast, using a shrimp fishing boat with “double-rig” nets sampling at stations up to 40 m depth. Sex ratios were female-biased only in zones with high reproductive activity such as in stations deeper than 15 m (χ2 test, p<0.05). The mean size of males and females was 15.3 ± 3.1 mm CL and 16.2 ± 4.7 mm CL, respectively, with size at sexual maturity estimates (CL50) of 14.8 mm for males and 15.5 mm for females. Mean growth curves provided estimates of CL∞ = 29.31 mm, k = 0.009/day, t0=−0.25 and CL∞ = 35.33 mm, k = 0.006/day, t0=−0.23 for males and females, respectively, and average lifespans of 1.35 for males and 2.12 years for females. Recruitment and abundances of reproductive females were highly correlated with the environmental factors such as higher water temperature and finer-grained bottom sediment (canonical correlation, r=0.63, p<0.001). The reproductive peaks in February-April 1998, March-May 1999 and February-May 2002 were followed by recruitment peaks in May-July 1998, July-September 1999 and April-June 2002, respectively. Thus, the proposed period of fisheries closure (March to May) does not coincide with the main recruitment periods observed for X. kroyeri.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The rapid synthesis of Mn3O4 powders by a two-step process of pyro-synthesis of ethylene glycol-metal nitrate precursor assisted by nitric acid is reported. A new strategy that accelerates the synthesis and allows obtaining highly pure crystalline Mn3O4 is discussed. The structural and morphological characteristics of the Mn3O4 powders are presented and discussed. The mechanism of formation of the Mn3O4 is also discussed. In comparison with other synthesis methods, the present method shows that the proposed route of synthesis has the main advantage of high production of the powder material in a very short time.