99 resultados para Three temperature


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Dielectric ceramics have been widely investigated and used for microwave applications such as resonators and filters. The present study deals with the influence of sintering temperature on microwave dielectric properties of TiO2 ceramics with 10, 20, and 30 wt% ZrO2. Three compositions have been developed through mixing procedures and then tested for each sintering temperature: 1500 and 1400°C. X-ray diffraction and scanning electron microscopy are carried out aiming to explain the ceramic behavior of each sample. The dielectric constants of different ceramics for both temperatures varied from 85.4 to 62.6, while their quality factor due to dielectric losses varied from 3110 to 1630. The Q decrease is attributed to the non uniform grain growth and to the obtained crystalline phases. The best microwave parameters were obtained for the ceramics sintered at 1400°C, which can be applied in microwave circuits as dielectric resonators. © (2010) Trans Tech Publications.

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The objective of this study was to evaluate the effects of three water and storage temperatures on the oocytes of the jundiá catfish, Rhamdia quelen. A factorial experimental design over time, with treatments completed in triplicate every 48 h, was used (5 × 3 × 3 × 3) to study the exposure of the oocytes to temperatures of 15, 25 and 35. °C and activated with water at 15, 25 and 35. °C each at 0, 45, 90, 135 and 180 minutes post-collection. Linear regression analysis for the response surface model indicated an interaction (p<0.05) between time and temperature of exposure with greater values for fertilization, hatching and normal larvae rates at the time of oocyte collection (70.2 ± 8.4% fertilized oocytes, 66.7 ± 29.4% hatched eggs and 30.3 ± 25.0% normal larvae). According to the statistical model, the water temperature that resulted in the highest fertilization rate was 25.6. °C (p<0.05). The rates of fertilization, hatching and normal larvae correlated positively (p<0.05) with one another, showing that these parameters can be used in the measurement of oocyte quality. Artificial fertilization of oocytes is recommended immediately after collection; if storage is necessary, it should be carried out at 15. °C. © 2011 Elsevier B.V.

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Our aim was to investigate the population fluctuation and the damage caused by the phytophagous mites Calacarus heveae Feres, Tenuipalpus heveae Baker, and Eutetranychus banksi (McGregor) on clones FX 2784, FX 3864, and MDF 180 in rubber tree crops from southeastern Bahia, Brazil. Moreover, we tested for the influence of climatic variables on occurrence patterns of these species throughout weekly samples performed from October to April. The infestation peaks was between mid-January and late February. The clones FX 2784 and FX 3864 had the highest infestations and more severe damage possibly caused by C. heveae, which was the most frequent and abundant species in all clones. We found that sunlight duration and rainfall were the most important factors for C. heveae while T. heveae was affected by rainfall and temperature. Eutetranychus banksi was only affected by sunlight duration. However, the best models had low goodness of fit. We concluded that the clones FX 2784 and FX 3864 had a higher susceptibility to mite attack, and the association between climatic variables and favorable physiological conditions were determinant for the population increase of the species from January to April. © 2012 Sociedade Entomológica do Brasil.

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This study aimed to define the best substrate and temperature for the emergence of Phacelia sp. seedling, annual ornamental flower gardens. The experimental design was entirely randomized in a factorial scheme 37 (three different types of substrates: vermiculite, sand and sphagnum combined with seven temperature conditions: room temperature, constant at 20, 25, 30 and 35C, and alternated at 20-30C and 25-35C) with 4 replications of 100 seeds each. Emergence (%E) and Emergence Rate (ER) were evaluated. The means of the resulting values were then compared by the Tukey test at 5% confidence level. There was a significant interaction amongst substrates and temperatures for all analyzed variables. For seeds sown in vermiculite and sand, the seedlings had higher %E and emerged fastest at 20C, room temperature and 20-30C that did not present statistically significant data. In sphagnum, seedlings showed greater %E in the alternated at 20-30C, room temperature and 20C and emerged quickly at room temperature and 20C that did not present statistically significant data. At room temperature and 20C, the seedlings had higher %E and emerged faster in vermiculite and sand that did not present statistically significant data. At 25, 30 and 25-35C, the seedlings showed better %E and emerged fastest in sand. At 35C, the seedlings showed either in vermiculite and sand were not significantly different in their emergence, but emerged faster in sand. There was not significantly different among substrates in their emergence at 20-30C, but the seedlings emerged faster in vermiculite and sand. It was concluded that the Phacelia sp. seedlings in all substrates showed greater %E at room temperature, 20C and 20-30C. For all temperatures, the seedlings growth parameters were superior when seeds were sown in sand.

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Telenomus remus Nixon is a promising biocontrol agent as an egg parasitoid of Spodoptera spp., but the lack of information on the host-parasitoid interactions in this system precludes its applied use in agriculture. Therefore, we studied the parasitism capacity of T. remus on eggs of Spodoptera cosmioides (Walker), Spodoptera eridania (Cramer), and Spodoptera frugiperda (Smith) in a range of temperatures (19, 22, 25, 28, 31, and 34 ± 1°C) under controlled conditions (70 ± 10% RH and 12 h photophase). Egg masses of Spodoptera spp. were offered to a single-mated T. remus female on a daily basis. More than 80% lifetime parasitism on eggs of S. cosmioides, S. frugiperda, and S. eridania was reached from 1 to 5, 1 to 7, and 1 to 9 days, respectively, at temperatures from 19 to 34°C. More than 80% parasitization was obtained at extreme temperatures for all hosts studied. Lifetime parasitization of S. frugiperda, S. cosmioides, and S. eridania was affected by temperature, with the lowest values for S. frugiperda (34°C) and S. cosmioides (19 and 34°C). Parasitization of S. eridania eggs was reduced around 18% at 28 and 31°C, but dropped more severely at 34°C. Parasitoid longevity was reduced as temperature increased. Thus, our data indicated that T. remus might be suitable as a biocontrol agent against S. eridania, S. cosmioides, and S. frugiperda in geographical areas that fit the temperature range studied here, even though T. remus parasitism was reduced at 34°C. © 2013 Sociedade Entomológica do Brasil.

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In horses, spermatogenesis normally occurs at an average intratesticular temperature of 35. °C; therefore, mechanisms for testicular thermoregulation are essential. Measuring the scrotal surface temperature by thermography is one of the methodologies used to evaluate the effectiveness of testicular thermoregulation. The objective of this study was to determine the relationship between the control of scrotal surface temperature and sperm quality in horses of different ages. In total, 24 Quarter Horse stallions were divided into three groups: YS (young stallions), AS (adult stallions) and OS (old stallions). Initially, we calculated the testicular volume (TV) and evaluated various aspects of the semen (sperm kinetics, plasma membrane integrity and sperm morphology) for all the animals. We also evaluated rectal temperature (RT), body surface temperature (BST,) and average scrotal surface temperature in the testicular region (SST) before (M0) and after sun exposure (M1). Differences were observed (p<0.05) between the RT and BST before and after sun exposure in all three groups. However, there were no differences (p>0.05) in the SST values at these two time points, thus demonstrating the efficiency of the mechanisms for testicular thermoregulation. The SST was similar (p>0.05) among all three groups. Based on these results, we conclude that fertile stallions of different age groups are able to maintain SST and measuring the heat radiating from the scrotum using a digital infrared thermographer. We can also conclude that measuring the heat radiating from the scrotum using a digital infrared thermographer is a practical and efficient tool for monitoring SST in horses. © 2013 Elsevier B.V.

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The outdoor cultivation (ditches) of Agaricus blazei was evaluated in the protected natural area (APA) of the mountainous region of Baturité on three types of casing soils (A, B and C). Casing soil A (horizon A) of the local soil was used (Alfisol). Casing B was obtained with a mixture of 30% of eucalyptus charcoal (1-2 cm of length) and 70% of horizon B of the local soil. Casing C was composed of 25% of vermiculite, 25% of coconut fiber and 50% of coarse sand. Temperature, relative humidity and pluviometric rates were monitored. The physical-chemical properties of the three casing soils were analyzed. The effect of the casing soil on the number and weight of the mushrooms, productivity, yield and biological efficiency of A. blazei were evaluated. The yield, productivity, biological efficiency and number of mushrooms were higher when using soil A. The highest productivity for soil A was attributed mainly to the physical characteristics, which were considered more appropriate for the cultivation, in addition to the high pluviometric rates and relative humidity. The productivity with soil A (9.62%) is comparable with the average productivity obtained in Brazil, meaning that the cultivation of A. blazei in this APA may have good perspectives for cultivation.

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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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Roystonea regia (Kunth) O.F. Cook is largely used as ornamental. The propagation is done almost exclusively by seeds; however, there is a great variation in the germination process influenced by many factors. The objective of this work was to study the effects of the temperature and maturation stages on the germination of R. regia seeds. The experimental design was entirely randomized in a factorial arrangement 6x3 (six temperatures: constant at 20, 25, 30 and 35 degrees C and alternated at 20-30 and 25-35 degrees C, with a photoperiod of 12 hours; and three fruit maturation stages: brown, yellow and black), with four replications of 25 disseminules (seed with stucked endocarp) each. The disseminules had their mesocarp and exocarp were removed and shade dried. Their moisture content was determined, and then they were placed in plastic boxes (gerbox type) containing vermiculite. The disseminules, with the germinative intumescence, were daily noted until germination was steady. The germination rate and the germination speed index were calculated, and the data were submitted to the variance analysis. The means were compared by the Tukey test. It was concluded that the highest germination rate (99.7%) and germination speed were obtained by seeds from mature (black) fruits at the temperature of 35 degrees C.

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

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The purpose of this study was to compare temperature variation during osteotomies with trephine drills under different irrigation conditions: without irrigation, external irrigation, and double irrigation.Synthetic blocks of bone (type I density) were used for drilling procedures with an experimental computed machine, which measured the maximum temperature in the cortical bone during osteotomy with a bone cut that was 5 mm in both diameter and depth. Three groups were formed depending on the irrigation conditions: no irrigation (G1), external irrigation (G2), and double irrigation (G3). Fifty drillings were performed for each group.The average thermal increase in the groups was 21.7 +/- 1.52 A degrees C in G1, 14.2 A +/- 0.70 A degrees C in G2, and 12.4 A +/- 0.75 A degrees C in G3. The results presented statistically significant differences among all groups (alpha = 0.05).The double irrigation technique resulted in a smaller increase in temperature in the cortical bone model, demonstrating a greater efficiency, which may be beneficial when compared to external irrigation alone.The trephine has been widely used in removing small blocks for bone graft, especially the posterior mandible, where the possibility of heating may be higher due to the density of cortical bone in this area. So it is important that the professionals select instruments that can reduce the risks of complications in the proposed treatment.

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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)