942 resultados para Shell-and-tube heat exchanger
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The solutions of a renormalized BCS equation are studied in three space dimensions in s, p and d waves for finite-range separable potentials in the weak to medium coupling region. In the weak-coupling limit, the present BCS model yields a small coherence length ξ and a large critical temperature, T c, appropriate for some high-T c materials. The BCS gap, T c, ξ and specific heat C s(T c) as a function of zero-temperature condensation energy are found to exhibit potential-independent universal scalings. The entropy, specific heat, spin susceptibility and penetration depth as a function of temperature exhibit universal scaling below T c in p and d waves.
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This work was conducted aiming to evaluate the effect of dietary energy level and the previous heat exposure on the respiratory activity of the mitochondria from the cardiac muscle of broiler chickens. It was used broiler chickens (Hubbard) from both sexes and fed with diet containing 2900 kcal ME/kg or 3200 kcal ME/kg. The birds were heat stressed (35°C/4h) in the 1 st, 21 st and 42 nd days of age. The respiratory activity of mitochondria from cardiac muscle was evaluated in a Gilson oxygraph, model 5/6, by using alpha-ceto-glutaric as substrate and the ADP (adenosine-di-phosphate) to stimulate the respiratory activity. There was not effect of dietary energy level and previous heat exposure on the respiratory activity of the mitochondria from cardiac muscle. However, the females presented higher respiratory activity than males. By reason of the low oxidative capability of the heart muscle fiber of the male broiler chickens, these could be more sensitive to cardiac disease than females.
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This work deals with the Priestley-Taylor model for evapotranspiration in different grown stages of a bean crop. Priestley and Taylor derived a practical formulation for energy partitioning between the sensible and latent heat fluxes through the α parameter. Bowen ratio energy balance (BREB) was carried out for daily sensible and latent heat flux estimations in three different crop stages. Mean daily values of Priestley-Taylor α parameter were determined for eleven days during the crop cycle. Diurnal variation patterns of α are presented for the growing, flowering and graining periods. The mean values of 1.13 ± 0.33, 1.26 ± 0.74, 1.22 ± 0.55 were obtained for a day in the growing, in the flowering and for graining periods, respectively. Eleven days values of α are shown and gave a mean value of 1.23 ± 0.10 which agree on the reported literature.
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This paper discusses the formation of microstructures with different volume fractions, as an outcome of a specific heat treatment, with the following phases: ferrite, martensite, bainite and retained austenite. For the microstructure characterization it is developed a chemical etching that allows to distinguish the phases by optical microscopy. The evaluation of the mechanical properties is done based on the results of tensile and fatigue tests. The experimental results show that appropriate heat treatments can contribute to a significant improvement in the mechanical properties of the steel. In this process it is essential to control the fraction volume, morphology of the phases, and grain size.
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Purpose: This study evaluated the potential effects of denture base resin water storage time and an effective denture disinfection method (microwave irradiation at 650 W for 6 minutes) on the torsional bond strength between two hard chairside reline resins (GC Reline and New Truliner) and one heat-polymerizing denture base acrylic resin (Lucitone 199). Materials and Methods: Cylindrical (30 x 3.9 mm) denture base specimens (n = 160) were stored in water at 37°C (2 or 30 days) before bonding. A section (3.0 mm) was removed from the center of the specimens, surfaces prepared, and the reline materials packed into the space. After polymerization, specimens were divided into four groups (n = 10): Group 1 (G1) - tests performed after bonding; Group 2 (G2) - specimens immersed in water (200 ml) and irradiated twice (650 W for 6 minutes); Group 3 (G3) - specimens irradiated daily until seven cycles of disinfection; Group 4 (G4) - specimens immersed in water (37°C) for 7 days. Specimens were submitted to a torsional test (0.1 Nm/min), and the torsional strengths (MPa) and the mode of failure were recorded. Data from each reline material were analyzed by a two-way analysis of variance, followed by Neuman-Keuls test (p = 0.05). Results: For both Lucitone 199 water storage periods, before bonding to GC Reline resin, the mean torsional strengths of G2 (2 days - 138 MPa; 30 days - 132 MPa), G3 (2 days - 126 MPa; 30 days - 130 MPa), and G4 (2 days - 130 MPa; 30 days - 137 MPa) were significantly higher (p < 0.05) than G1 (2 days - 108 MPa; 30 days - 115 MPa). Similar results were found for Lucitone 199 specimens bonded to New Truliner resin, with G1 specimens (2 days - 73 MPa; 30 days - 71 MPa) exhibiting significantly lower mean torsional bond strength (p < 0.05) than G2 (2 day - 86 MPa; 30 days - 90 MPa), G3 (2 days - 82 MPa; 30 days - 82 MPa), and G4 specimens (2 days - 78 MPa; 30 days - 79 MPa). The adhesion of both materials was not affected by water storage time of Lucitone 199 (p > 0.05). GC reline showed a mixed mode of failure (adhesive/cohesive) and New Truliner failed adhesively. Conclusions: Up to seven microwave disinfection cycles did not decrease the torsional bond strengths between the hard reline resins, GC Reline and New Truliner to the denture base resin Lucitone 199. The effect of additional disinfection cycles on reline material may be clinically significant and requires further study. Copyright © 2006 by The American College of Prosthodontists.
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The thermophilic fungus Thermoascus aurantiacus 179-5 produced large quantities of a glucosidase which preferentially hydrolyzed maltose over starch. Enzyme production was high in submerged fermentation, with a maximal activity of 30 U/ml after 336 h of fermentation. In solid-state fermentation, the activity of the enzyme was 22 U/ml at 144 h in medium containing wheat bran and 5.8 U/ml at 48 h when cassava pulp was used as the culture medium. The enzyme was specific for maltose, very slowly hydrolyzed starch, dextrins (2-7G) and the synthetic substrate (α-PNPG), and did not hydrolyze sucrose. These properties suggest that the enzyme is a type II α-glucosidase. The optimum temperature of the enzyme was 70°C. In addition, the enzyme was highly thermostable (100% stability for 10 h at 60°C and a half-life of 15 min at 80°C), and stable within a wide pH range. Copyright © 2006, The Microbiological Society of Korea.
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The goal of this experiment was to study the latent and sensible heat variation determined by Bowen ratio from an irrigated soybean crop. A micrometeorological station with vertical displacement was constructed to maintain the same level of all measures over the canopy. The station was installed in the center of the crop, and it was over 130 m away from the main edge of the predominant wind direction. Fluxes were calculated by vertical temperature gradient determined at 0.15 and 1.15 m over the canopy. The latent heat flux was the mean energy consumer when the canopy covered the soil totally, and there were good soil water conditions. The sensible heat flux was greater when the soil was not totally covered by the canopy. The canopy was essential on the amount of latent heat dissipated by the crop.
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CAE is caused by a lentivirus. The animals are mainly infected when taking contaminated colostrums and/or milk. This study proposed a CAE control strategy without sacrificing contaminated mothers. Thirty-nine female kids, born to CAE seropositive mothers were isolated from their mothers at birth and fed heat-treated colostrums and pasteurized milk from seronegative goats up to two months of age. All kids were submitted to three-monthly serological tests from birth to 12 months; seropositives were segregated from the herd. The control group consisted of 12 kids born to seropositive mothers that remained with their mothers. Diagnosis was the same, but seropositve animals were not segregated. At the end of 12 months, 34 (87%) animals from the experimental group remained seronegative with 76% to 98% confidence limits; in control group animals, the accumulated negativity rate was 17%, with 0% and 38% confidence limits. These results show that the proposed plan is viable to assure disease control in contaminated herds and that without it contamination can pass to animals born to infected goats.
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New classes of martensitic stainless steels, with low carbon levels, have been developed aiming to meet the needs of the petroleum industry segment. However, their use has been restricted due to the fact it is a recent development and many of its properties are still under investigation. This work determines the values of initial and final temperatures for the austenitic transformation and the initial and final temperatures of martensitic formation for alloy 13Cr2Ni0,1C, by means of dilatometric tests under continuous cooling. Based on these results the optimized conditions for quench and temper heat treatments were obtained. The microstructural characterization of the alloys under coarse fusion condition was carried out by optical microscopy and the presence of delta-ferrite in the martensitic matrix was observed.
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Colour stability of resin and silicone is an important factor for longevity of facial prostheses. The aim of this study was to evaluate the colour stability of resins and silicone for facial prostheses. Three brands of acrylic resin and one of facial silicone were evaluated considering pigment incorporation for the colourless materials. Ten samples of each material were fabricated and submitted to measurements of chromatic alteration initially and after 90 and 180 days of weathering natural through visual analysis and spectrophotometry. Data were evaluated by ANOVA and Tukey test (p < 0.05). Statistically significant colour alteration was observed among some materials regardless of the period. The materials did not present a statistical difference between 90 and 180 days except for the pigmented heat-polymerized resin. The colour difference between pigmented Silastic MDX4-4210 and colourless Silastic was statistically significant (p < 0.01) in both periods as well as between pigmented and colourless heat-polymerized resin, and between the resins Rapidaflex and Lentaflex. The visual method demonstrated colour alteration in all materials evaluated during the first 90 days of ageing. All materials exhibited colour alteration due to exposure to environment. © 2012 Informa UK, Ltd.
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Following the thermodynamic formulation of a multifractal measure that was shown to enable the detection of large fluctuations at an early stage, here we propose a new index which permits us to distinguish events like financial crises in real time. We calculate the partition function from which we can obtain thermodynamic quantities analogous to the free energy and specific heat. The index is defined as the normalized energy variation and it can be used to study the behavior of stochastic time series, such as financial market daily data. Famous financial market crashes-Black Thursday (1929), Black Monday (1987) and the subprime crisis (2008)-are identified with clear and robust results. The method is also applied to the market fluctuations of 2011. From these results it appears as if the apparent crisis of 2011 is of a different nature to the other three. We also show that the analysis has forecasting capabilities. © 2012 Elsevier B.V. All rights reserved.
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Breast implants are medical devices that are used to augment breast size or to reconstruct the breast following mastectomy or to correct a congenital abnormality. Breast implants consist of a silicone outer shell and a filler (most commonly silicone gel or saline). Approximately 5 to 10 million women worldwide have breast implants. Histomorphometric study to evaluate the biological tissue compatibility of silicone implants suitable for plastic surgery and the adverse effects and risks of this material. Thirty Wistar white rats received subcutaneous implants and the revestiment of silicone gel Silimed ®®, and randomized into six groups of five animals each, according to the type of implanted material and the time of sacrifice. Eight areas of 60.11mm2 corresponding to the obtained surgical pieces were analyzed, counting mesenchymal cells, eosinophils, and foreign body giant cells, observing an acceptable biocompatibility in all implants, for subsequent statistical analysis by Tukey test. Silicone gel showed inflammation slightly greater than for other groups, with tissue reactions varying from light to moderate, whose result was the formation of a fibrous capsule around the material, recognized by the organism as a foreign body. Despite frequent local complications and adverse outcomes, this research showed that the silicone and top layer presented an acceptable chronic inflammatory reaction, which did not significantly differ from the control group. In general, it is possible to affirm that silicone gel had acceptable levels of biocompatibility, confirmed the rare presence of foreign body giant cells, and when of the rupture, formed a fibrous capsule around the material, separating the material of the organism. © AVICENA 2013.
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Pós-graduação em Zootecnia - FCAV
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)