920 resultados para Temperatura de Neel


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The production of seedlings of passion fruit is done mainly with the use of seeds by most producers. It can also be propagated by cuttings, layering and in vitro tissue culture. However, even when grafting is used, it is necessary to use seeds to produce the rootstock. Nevertheless, most Passifloracea species have germination problems, making it difficult to obtain seedlings. Although several studies have been developed in an attempt to increase seed germination of passion fruit there are still difficulties in understanding the germination process and also disagreement about seed dormancy. Thus, the present study aimed to review papers related to seed germination of passion fruit emphasizing aspects such as mechanical resistance to water ingress, the need for adequate light and temperature and the use of plant growth regulators in overcoming seed dormancy. It was noticed that, in general, the passion fruit seeds are photoblastic negative and exhibit physiological dormancy, being no need of seed scarification to stimulate its germination.

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The objective of this study was evaluate the effects of retification® temperatures and times on thickness variation from Eucalyptus grandis timber. Boards from logs of 30-year-old Eucalyptus grandis trees, from São Paulo Forest Institute in Santa Barbara, Brazil, were thermally modified at 180ºC for 2.5 hours, at 200ºC for 3.0 hours and 200ºC for 4.0 hours. The results showed that: (1) the thermally modified wood at 200°C by 3.0 to 4.0 hours showed increased thickness between 0.698 mm and 0.874 mm due to the internal cracks, (2) the thermally modified wood at 180°C by 2.5 hours has a decreased from 0,177 mm in thickness and the absences of internal cracks.

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The use of Information and Communication Technology has grown in most agricultural activities. As a consequence, it has changed the way of thinking and acting of the farmer who wants to establish a more and more competitive market. However, the high costs of acquisition and maintenance of those technologies may be a factor which can inhibit its spread and acceptance, mainly to a large number of small grain Brazilian farmers. In this context, there is a need for innovative solutions that are proper for this universe of farmers. Starting from this premise, this paper presents the development of a low cost prototype to the monitoring process of temperature and humidity values of grains stored in silos, using communication based on wireless technology by radio frequency. Therefore, the economic implications of cost/benefit ratio of innovative application of wireless transmission in the process of thermometry of grains were analysed. The prototype was made of two electronic units, one of acquisition and another one of data reception, as well as computational software, which offered the farmer more precise information for the control of aeration. By means of stability, integrity and reliability tests of data transmission via radio, using low cost electronic components, the development system can be considered as potentially viable. It presented the difference regarding the wireless communication via radio in the process of grains thermometry, providing mobility, reducing cabling costs and maintenance, and also offering an easy system expansion; it was also appropriate to temperature and humidity monitoring in grain silos; and revealed operational viability, besides the low cost development when compared to similar products available in the Brazilian market.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The aim of this study was to analyze the behavior of the flow of heat (temperature) through the thickness of panels LVL (Laminated veneer lumber) produced with phenol formaldehyde adhesive, in laboratorial and industrial scales. Experimental program was conducted with five LVL panels (three produced in laboratorial scale and two in industrial scale) with different arrangements of a mix of commercial veneers from tropical pinus from the south region of Sao Paulo State, Brazil, bonded using phenol formaldehyde adhesive. The temperature inside the panels during the pressing process was evaluated using thermocouples type T (cooper-constantan), installed mostly in the center of the glue lines and connected to a data acquisition system. The graphics of temperature as a function of the time showed a gradual increase of temperature up to pre-set values, remaining constant from them. The temperature reached at the center of the panels was adequate to promote the curing of the adhesive. These pre-set values were similar to the minimum values presented by other authors and manufacturers of these adhesives that affirm that temperatures above 100ºC at the center of laminated panels bonded with phenolic adhesives are sufficient to ensure proper cure of the resin. The time necessary for curing of the adhesives confirmed the validity of practical expressions provided by adhesive manufacturers.

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The objective of the present work was to evaluate the in vitro mycelial growth of ten L. edodes strains (LED 12, LED 20, LED 25, LED 27, LED 33, LED 35, LED 51, LED 55, LED 58 and LED 75) submitted to the temperatures of 15, 20 and 25 ºC. An agar medium prepared with eucalyptus wood extract and soy bran was used and radial measurement of the mycelial growth of L. edodes strains was performed. The experimental design was totally randomized, in a 10 x 3 factorial scheme. Each treatment corresponded to a Petri plate and consisted of 5 repetitions. It was verified that L. edodes growth is influenced by the incubation temperature, that is the temperature of 25 ºC was the most favorable for the mycelial growth of all L. edodes strains, especially for LE 75, LE 55, LE 33 and LE 12 strains, which obtained the highest mycelial growth averages at 25 ºC at the end of the cultivation cycle.

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The present study was aimed to evaluate different (semi-solid) media for the production of Metarhizium anisopliae and Beauveria bassiana propagules, and to evaluate the tolerance of these propagules to ultraviolet radiation and temperature. The experiments were performed at the Biological Control Laboratory of the Instituto Biológico at Campinas, São Paulo, Brazil. For both fungi, 6 repetitions were performed for each of the 17 treatments: corn starch, full rice, parboiled rice, type-1 rice, type-2 rice, oat flakes, canjiquinha [grits], wheat flour, raw cassava flour, yellow corn flour, special wheat flour, corn flour, corn in grains, cassava starch, soy in grains, crushed wheat, and turf. The viability analysis was done in plastic plates containing BDA. For the bioassays involving exposure to ultraviolet light and temperature, BDA was also used for viability analysis, and each treatment was exposed to the UV radiation for 0, 25 and 50 seconds, the temperature exposure being at 20, 25, 30 and 35º C. Using a Potter tower, 2 mL of fungus suspension from each treatment was inoculated to the Diatraea saccharalis caterpillars. Regarding the sporulation, the largest concentrations of M. anisopliae and B. bassiana were found for the treatments with parboiled rice, type-1 rice, type-2 rice, yellow corn flour, corn flour and crushed wheat. The viability of all treatments was superior to 94.00%. Also, the longer the duration of the exposition to the UV, the smaller the number of fertile conidia. At 35o C, a significant loss of conidia viability was observed, and all the treatments presented some level of virulence.

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This study aimed the avocado ‘Hass’ conservation with the use of radiation. We performed two experiments: Experiment I – fruits irradiated with different doses of cobalt-60 gamma irradiation(0,0; 0,2; 0,4; 0,6 e 1,0 kGy); Experiment II – fruit irradiated by electron accelerator in different doses (0,0; 0,48; 0,8; 1,12 e 1,45 MeV), both maintained at room temperature of 21±1 °C and at relative humidity of 79±5 %. Antioxidant capacity, total phenolic compounds, fresh weight loss, and respiration rate evaluation were performed every three days for 12 days. The experimental design was completely randomized with three replicates per treatment. For statistical analysis, the Tukey test at 5% probability was employed. Under the conditions in which the experiments were performed, the results showed that the gamma radiation use retained the fruits for 12 days, regardless the doses applied. The radiation by electron accelerator use also promote the fruits preservation, regardless the doses employed.

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Pós-graduação em Física - IFT

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Snakes are ectothermic animals and, therefore, their physiological functions are strongly affected by temperature. For instance, the resting metabolic rate (RMR) of this animals increase with the rise in body temperature. However, metabolic determinations in ectothermic organisms, including snakes, are generally made by submitting the animals to constant temperature regimes. This experimental procedure, although widely used, accepted and certainly suitable in several cases, submit the animals to a very different situation from that experienced by them in nature. In fact, ectothermics are known by presenting extensive variations in their body temperatures trough the day and/or seasons. If this disagreement between the thermal biology of the animals and the experimental conditions, for instance over the circadian cycle, affects the determinations of metabolic rates of ectotherm animals, remains quite uncertain. Thus, this study aimed to test the effects of different thermal regimes (fluctuating vs constant) in different temperature ranges over the TMR of rattlesnakes (Crotalus durissus). Therefore, the TMR of rattlesnakes was measured by the oxygen consumption rates ( V O2) in the constant temperatures of 15°C, 20°C, 25°C, 30°C and 35°C. For fluctuating regimes, snakes were measured in thermoperiods of 12/12 hours, as follows: 15°C and 25°C; 20°C and 30°C; 25°C and 35°C. Our results show that the RMR of C. durissus rises as the temperature increases, regardless of the thermal regime. The obtained RMR in the constant regimes of 20°C and 25°C was not different from that measured in the correspondent fluctuating regimes (i.e., 15 - 25°C e 20 - 30°C). However, at constant 30°C, the RMR was significantly higher than that obtained in the 30°C fluctuating regime (25 - 35ºC). This indicates that the potential effects in submitting of snakes to different thermal regimes of its thermal biology become more important with...

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Snakes are ectothermic animals and, therefore, their physiological functions are strongly affected by temperature. For instance, the resting metabolic rate (RMR) of this animals increase with the rise in body temperature. However, metabolic determinations in ectothermic organisms, including snakes, are generally made by submitting the animals to constant temperature regimes. This experimental procedure, although widely used, accepted and certainly suitable in several cases, submit the animals to a very different situation from that experienced by them in nature. In fact, ectothermics are known by presenting extensive variations in their body temperatures trough the day and/or seasons. If this disagreement between the thermal biology of the animals and the experimental conditions, for instance over the circadian cycle, affects the determinations of metabolic rates of ectotherm animals, remains quite uncertain. Thus, this study aimed to test the effects of different thermal regimes (fluctuating vs constant) in different temperature ranges over the TMR of rattlesnakes (Crotalus durissus). Therefore, the TMR of rattlesnakes was measured by the oxygen consumption rates ( V O2) in the constant temperatures of 15°C, 20°C, 25°C, 30°C and 35°C. For fluctuating regimes, snakes were measured in thermoperiods of 12/12 hours, as follows: 15°C and 25°C; 20°C and 30°C; 25°C and 35°C. Our results show that the RMR of C. durissus rises as the temperature increases, regardless of the thermal regime. The obtained RMR in the constant regimes of 20°C and 25°C was not different from that measured in the correspondent fluctuating regimes (i.e., 15 - 25°C e 20 - 30°C). However, at constant 30°C, the RMR was significantly higher than that obtained in the 30°C fluctuating regime (25 - 35ºC). This indicates that the potential effects in submitting of snakes to different thermal regimes of its thermal biology become more important with...