76 resultados para 637


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The structural and electronic properties of SrZrO3 selected surfaces were investigated by means of density functional theory applied to periodic calculations at B3LYP level. The relaxation effects for two symmetric and asymmetric terminations are analyzed. The electronic and energy band properties are discussed on the basis of band structure as well density of states. There is a more significant rumpling in the SrO as compared to the ZrO2 terminated surfaces. The calculated indirect gap is 4.856, 4.562, 4.637 eV for bulk, ZrO2 and asymmetric terminations, respectively. The gap becomes direct; 4.536 eV; for SrO termination. The contour in the (110) diagonal plane indicates a partial covalent character between Zr and 0 atoms for the SrO terminated surface. (c) 2007 Elsevier B.V. All rights reserved.

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The capacitor placement (replacement) problem for radial distribution networks determines capacitor types, sizes, locations and control schemes. Optimal capacitor placement is a hard combinatorial problem that can be formulated as a mixed integer nonlinear program. Since this is a NP complete problem (Non Polynomial time) the solution approach uses a combinatorial search algorithm. The paper proposes a hybrid method drawn upon the Tabu Search approach, extended with features taken from other combinatorial approaches such as genetic algorithms and simulated annealing, and from practical heuristic approaches. The proposed method has been tested in a range of networks available in the literature with superior results regarding both quality and cost of solutions.

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This study was carried out to determine body composition and magnesium, potassium and sodium requirements for weight gain of Santa Ines lambs (hairy coat breed). Eighteen animals were used with average 15 kg initial LW. At the beginning of the experiment, six animals were slaughtered for the determination of the amount of each mineral retained in the body, and serving as reference animals in the comparative slaughter technique. The remaining 12 animals were divided in two groups: six were ad libitum fed and six animals were restricting fed at maintenance plus 20%. The animals from the ad libitum and restrict feeding groups started in the experimental period by pairs and they both were slaughtered when the animals from the ad libitum group reached 25 kg LW. The estimates of magnesium, potassium and sodium body composition were obtained through the prediction equations obtained by the logarithm regression of the amount of each present minerals in the empty body in function of the empty body weight (EBW). The net requirements for weight gain were obtained through the derivation of these prediction equations. The estimates of body composition per kg EBW for the animals from 15 to 25 kg were: 0.591 and 0,578 g for Mg: 2.914 and 2.776 g for K 1.830 and 1.637 g for Na; and the net requirements for kg weight gain were: 0.515 and 0.503 g for Mg: 2.408 and 2.294 g for K; 1.315 and 1.177 g for Na, respectively.

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Bioactivity-guided fractionation of a CH2Cl2 extract from leaves of Piper hispidum (Piperaceae) yielded a new pyrrolidine amide, N-[7-(3',4'-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine 1, in addition to two known amides N-[5-(3',4'-methylenedioxyphenyl)-2(E)-pentadienoyl]pyrrolidine and N-[2-(3',4'-methylenedioxy-6'-methoxyphenyl)-2(Z)-propenoyl]pyrrolidine. The structure of compound 1 was elucidated by interpretation of spectral data, including ES-MS. Compound 1 showed antifungal activity against Cladosporium sphaerospermum.

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The objective of this study was to evaluate the allelophatic potential ethanol extract of leaves of Anadenanthera macrocarpa (Benth.) Brenan (angico) and Astronium graveolens Jacq (aroeira) on the biomonitor germination of Brassica chinensis (Malaysia's cabbage) and Lactuca sativa (lettuce). For the test of allelopathy was the bioassay of germination of B. chinensis and L. sativa using solutions of ethanol extracts in different concentrations (5, 10 and 20 mg / mL) with continuous light for 11 days. The experimental and control groups were divided into the Petri dish containing 50 seeds of B. chinensis and L. sativa each. Were performed six replicates for each concentration of extract of leaves of A. macrocarpa and A. graveolens and the negative control (water). The rolling action of the treatments was performed by quantitative observation and monitoring of germination every six hours. The results show that the ethanol extract of A. macrocarpa and A. graveolens presents allelopathic potential, regardless of the concentration used, but with answers dose-dependent, and thus able to interfere directly in germination, average speed and time of germination biomonitor of B. chinensis and L. sativa.

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The objective of this work was to estimate, by meta-analysis, the heritability (h(2)) and the genetic (r(g)) and phenotypic (r(f)) correlations of residual feed intake (RFI), and of its component traits in beef cattle from 19 breeds or genetic groups. Twenty-two scientific papers published from 1963 to 2011, from eight countries, totaling 52,637 cattle of ages from 28 days up to slaughter, were evaluated. The estimates of RFI, dry matter intake (DMI), average daily gain (ADG) and metabolic weight (BW0.75) were weighted by the inverse of sample variance. The variation between studies of h(2) for each trait was analyzed by weighted least squares. The effects of sex, country and breed were significant for h(2) of RFI, explaining 67% of variation between studies. For DMI, country and breed effects were significant and explained 96% of variation. Pooled estimates of h(2) were: 0.255+/-0.008, 0.278+/-0.012, 0.321+/-0.015, and 0.397+/-0.032 for RFI, DMI, ADG and BW0.75, respectively. Pooled estimates of genetic and phenotypic correlations were low between RFI and ADG and between RFI and BW0.75 (from -0.021+/-0.034 to 0.025+/-0.035), and moderate between RFI and DMI (0.636+/-0.035 and 0.698+/-0.041) and between DMI, ADG and BW0.75 (0.441+/-0.062 to 0.688+/-0.032). The trait RFI has lower heritability estimates than its components.

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Fencamfamine (FCF) is a central stimulant that facilitates central dopaminergic transmission through inhibition of dopamine uptake and enhanced release of the transmitter. We evaluated the changes in the inhibition of uptake and the release of striatal [ 3H]-dopamine at 9:00 and 21:00 h, times corresponding to maximal and minimal behavioral responses to FCF, respectively. Adult male Wistar rats (200-250 g) maintained on a 12-h light/12-h dark cycle (lights on at 7:00 h) were used. In the behavioral experiments the rats (N = 8 for each group) received FCF (3.5 mg/kg, ip) or saline at 9:00 or 21:00 h. Fifteen minutes after treatment the duration of activity (sniffing, rearing and locomotion) was recorded for 120 min. The basal motor activity was higher (28.6 ± 4.2 vs 8.4 ± 3.5 s) after saline administration at 21:00 h than at 9:00 h. FCF at a single dose significantly enhanced the basal motor activity (38.3 ± 4.5 vs 8.4 ± 3.5 s) and increased the duration of exploratory activity (38.3 ± 4.5 vs 32.1 ± 4.6 s) during the light, but not the dark phase. Two other groups of rats (N = 6 for each group) were decapitated at 9:00 and 21:00 h and striata were dissected for dopamine uptake and relase assays. The inhibition of uptake and release of [ 3H]-dopamine were higher at 9:00 than at 21:00 h, suggesting that uptake inhibition and the release properties of FCF undergo daily variation. These data suggest that the circadian time-dependent effects of FCF might be related to a higher susceptibility of dopamine presynaptic terminals to the action of FCF during the light phase which corresponds to the rats' resting period.

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Bornite electrodes were characterized in the absence or in the presence of Acidithiobacillus ferrooxidans, which is an important microorganism involved in metal bioleaching processes. The presence of the bacterium modified the mineral/electrolyte interface, increasing the corrosion rate, as revealed by interferometric, AEM, ICP and EIS analyses. As a consequence of bacterial activity the electrode became porous, increasing its surface heterogeneity. This behavior was correlated with the evolution of impedance diagrams obtained during the time course of experiments. The main difference in these diagrams was the presence of an inductive feature (up to 44 h), which was related to bacterial action on the mineral dissolution, better than to its adhesion on the bornite. The total real impedance measured in presence of the bacterium was about 10 times lower than in its absence, due to the acceleration of the mineral dissolution, because an oxidant environment was maintained.

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Two highly sensitive and selective methods based on gas chromatography coupled to mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode have been developed for the quantification of 2,6-dichlorophenol (2,6-DCP), a sex pheromone of the tick females of Anocentor nitens. Standard addition method and calibration curve techniques using 5-bromine-4-hydroxy-3- methoxybenzaldehyde (5-BrV) as internal standard (IS) afforded detection limit of 0.1ngml-1. The calibration curve was linear over the concentration range from 0.5 to 500ngml-1 for 2,6-DCP. Results show that the concentration range of sex pheromone in the extracts samples was 1.08-10.35ngml-1. The methods developed provided reliable procedures to determine amounts of 2,6-DCP present in ticks. © 2003 Elsevier B.V. All rights reserved.

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The productivity and fruit size distribution of 28 processing tomato cultivars were analyzed to determine the ones with potential for fresh market. The experiment was done in Jaboticabal-SP, Brazil (21o15'22'' South, 48o18'58'' West, altitude 595 m), in a Haplorthox soil, from June to December. The cultivars H 7155, Hypeel 108, Andino, U 573, H 9036, Ipa 6, H 9494, AG 33, Yuba, RPT 1294, AG 72, Peelmech, Curicó, Hypeel 45, RPT 1478, H 9492, H 9498, H 2710, Hitech 45, Halley, Botu 13, H 9553, U 646, NK 1570, AG 45, RPT 1095, RPT 1570 and PSX 37511 were evaluated. The experimental design was randomized blocks, with four repetitions, and five plants per experimental unit. Fruits harvested from each experimental unit were counted, classified by transversal diameter (large, medium, small, very small and cull) and then weighed. Cultivars AG 72, H 9498, Hypeel 45, RPT 1095 and Curicó yielded more than 70 fruits per plant, on average. The total production per plant of cultivars AG 72, H 9498, Hypeel 45, H 7155, Hypeel 108, Halley, Hitech, RPT 1095, H 9494, H 9036 and Curicó was greater than 4 kg. Considering the weight of large and medium fruits, categories which are important for fresh market, the cultivars H 2710, Botu 13, U 573, Hypeel 45, Yuba, RPT 1294 and Ipa 6 presented values above 50% for production.

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The productivity of 28 tomato cultivars was evaluated over three stages of harvest. The study was carried out during from June to December of 1999 in an open field at the experimental area of the Section of Olericulture and Aromatic Medicinal Plants, Department of Crop Production at FCAV-UNESP, Jaboticabal, SP, Brazil. The cultivars studied were H 7155, Hypeel, Andino, U 573, H 9036, IPA 6, H 9494, AG 33, Yuba, RPT 1294, AG 72, Pelmeech, Curico, Hypeel 45, RPT 1478, H 9492, H 9498, H 2710, Hitech 45, Halley, Botu 13, H 9553, U 646, NK 1570, AG 45, RPT 1095, RPT 1570, and PSX 37511. The experimental design was a randomized block design with four repetitions, with five plants per plot. Productivity was evaluated at three stages of harvest at 119, 149 and 179 days after seeding. There were no significant differences among the cultivars at the first harvest (119 days). The majority of the cultivars produced their highest yield at the second harvest; the most productive cultivars were Curicó and AG 72, which yielded 4.69 and 4.67 kg/plant, respectively, although they did not differ statistically from the cultivars Hypeel 45 (4.35 kg/plant) and H 9498 (4.16 kg/plant). Yields of the cultivars Andino and H 9494 were evenly distributed between the second and third harvests. At the third harvest, cultivar IPA 6 had the highest yield (2.9 kg/plant) and was statistically different from all other cultivars except H 9036 (2.34 kg). These two cultivars had the most delayed and concentrated maturity, making them suitable for mechanical harvesting, although at a later time. Cultivar AG 72 had the greatest total yield (5.76 kg/plant), but it was not statistically different from cultivars Hypeel 45 (5.43 kg), Curico (4.17 kg), H 9498 (4.83 kg), H 7155 (4.58 kg) and Halley (4.55 kg). All of the cultivars, with the exception of cultivars H 9036, IPA 6, Andino and H 9494 showed in the second harvest concentrated maturity, making it suitable for mechanical harvesting.

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Fruit of 28 tomato cultivars for industrial processing were characterized to identify cultivars with potential for in natura consumption. The experiment was carried out in Jaboticabal-SP, Brazil (21o15'22'' South, 48o18'58'' West, altitude 595 m), on a Haplorthox soil during June-December. The cultivars used in this study were: H 7155, Hypeel 108, Andino, U 573, H 9036, Ipa 6, H 9494, AG 33, Yuba, RPT 1294, AG 72, Peelmech, Curicó, Hypeel 45, RPT 1478, H 9492, H 9498, H 2710, Hitech 45, Halley, Botu 13, H 9553, U 646, NK 1570, AG 45, RPT 1095, RPT 1570 and PSX 37511. The experimental design was randomized blocks, replicated four times. Ten fruits per plot were analyzed, evaluating the following characteristics: shape (oblong or round); length and diameter (mm); external and internal coloration; presence of fissures; number of loci; pulp thickness (mm); soluble solids content (Brix) and total acidity. Only cultivars Hypeel 108, AG 72, NK 1570, RPT 1570 had oblong fruit. Cultivars which had pulp thicker than 5.5 mm, a characteristic which is directly related to fruit yield for industrial purposes were: Ipa 6, Andino, U 646, H 9553, RPT 1294 and Hypeel 108. Cultivars Ipa 6 and Andino also presented elevated values for length, diameter and pulp thickness, indicating them as quality material for industry or, alternatively, for in natura market. Among the cultivars which presented better values for acidity (higher or equal to 0.3 g citric acid 100 g-1) were RPT 1095, AG 45, H 9553 and Hypeel 45.

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Using histochemical techniques, the present work describes the basic histochemical characteristics of the secretion in hypopharyngeal glands of Polistes versicolor (Olivier) and estimates the secretory activity in specimens of different ages. The secretory activity was determined by glandular cell diameter and by the amount of secretion present in the glands. The results did not reveal a relationship between these parameters and the age of the wasps, not allowing us to determine the development cycle of these glands throughout the wasps' life. Also, a relationship between glandular cell diameter and amount of secretion present in the glands was not observed.

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In order to evaluate the influence of exercise of different intensities on Red Blood Cell Distribution width (RDW) and Packed Cell Volume (VG) in Thoroughbred horses, blood was collected from 60 animals, 30 males and 30 females, subdivided in groups of horses with 24 to 36 months of age and not in training, and after 12 months of training, and horses with 36 to 48 months of age in training. Blood samples where collected before and after trot and gallop. Samples where analyzed with a automatic cell counter (Cell-Dyn 3500R, Abbott Diagnostic). Red Blood Cell Distribution width (RDW) values increased significantly after trot and gallop demonstrating a variation in the size of red blood cells, while Packed Medium Cell Volume (VGM) values did not show variations before or after exercise.

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Drosophila mulleri (MU) and D. arizonae (AR) are cryptic species of the mulleri complex, mulleri subgroup, repleta group. Earlier cytogenetic studies revealed that these species have different regulatory mechanisms of nucleolar organizing activity. In these species, nucleolar organizing regions are found in both the X chromosome and the microchromosome. In the salivary glands of hybrids between MU females and AR males, there is an interspecific dominance of the regulatory system of the D. arizonae nucleolar organizer involving, in males, amplification and activation of the nucleolar organizer from the microchromosome. The authors who reported these findings obtained hybrids only in that cross-direction. More recently, hybrids in the opposite direction, i.e., between MU males and AR females, have been obtained. The purpose of the present study was to evaluate, in these hybrids, the association of the nucleoli with the chromosomes inherited from parental species in order to cytogenetically confirm the dominance patterns previously described. Our results support the proposed dominance of the AR nucleolar organizer activity over that of MU, regardless of cross-direction. ©FUNPEC-RP.