Germination response of Hylocereus setaceus (Salm-Dyck ex DC: ) Ralf Bauer (Cactaceae) seeds to temperature and reduced water potentials

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

Effect of light and temperature on seed germination in Tibouchina mutabilis (Vell.) Cogn. (Melastomataceae)

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

Leaf heliotropism in Styrax camporum Pohl from the Brazilian cerrado: distinct gas exchange and leaf structure, but similar leaf temperature and water relations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Morphology of eggs of Dioctophyme renale Goeze, 1782 (Nematoda: Dioctophymatidae) and influences of temperature on development of first-stage larvae in the eggs

Este estudo teve a finalidade de fornecer dados morfológicos de ovos de D. renale e do desenvolvimento de larvas de primeiro estádio em ovos mantidos em diferentes temperaturas. Os ovos foram obtidos por centrífugação da urina de cães parasitados e colocados em placas de Petri em estufa BOD, durante 90 dias. O experimento consistiu de três tratamentos (GI - 15 ºC, GII - 20 ºC e GIII - 26 ºC) com cinco repetições cada. Os ovos apresentaram tamanho médio de 67,23 x 42,78 µm, e o tempo médio de incubação foi inversamente proporcional à temperatura de incubação e as larvas apresentaram motilidade por aproximadamente uma semana após sua formação.

Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

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

Temporary storage of jussara palm seeds: effects of time, temperature and pulp on germination and vigor

As sementes da palmeira juçara (Euterpe edulis Mart.) são recalcitrantes, apresentando baixa longevidade e sensibilidade à desidratação e ao armazenamento em temperaturas baixas. Neste trabalho foram estudadas condições de temperatura mais adequadas ao armazenamento temporário destas sementes com e sem a polpa. Frutos maduros foram colhidos em 24 plantas provenientes da coleção de palmeiras do Instituto Agronômico (IAC) localizada em Ubatuba, estado de São Paulo, e encaminhadas, em embalagem impermeável, à Faculdade de Ciências Agronômicas da UNESP, Campus de Botucatu (SP). Metade dos frutos foi despolpada e outra metade foi mantida com polpa, sendo ambas armazenadas em sacos fechados de polietileno (20 µm de espessura) mantidos em temperaturas de 5; 10; 15 e 20-30ºC. Amostras para os testes de qualidade foram retiradas aos 0; 3; 6; 9 e 12 dias após a colheita dos frutos. As sementes armazenadas com polpa foram despolpadas imediatamente antes da instalação dos testes. Foram avaliados o grau de umidade das sementes, porcentagem de germinação, comprimento e matéria seca das plântulas. Os resultados mostraram que há efeito positivo de pós-amadurecimento em sementes de Euterpe edulis. Um período de armazenamento de 9 a 12 dias, após a colheita e antes da semeadura, favoreceu a germinação e o vigor das sementes de juçara. Os efeitos foram maiores para sementes armazenadas sem polpa do que com polpa. Temperaturas na faixa de 5 a 20-30ºC são igualmente adequadas para o armazenamento temporário de sementes sem polpa. No entanto, para sementes com polpa, a temperatura de armazenamento não deve exceder a 20ºC, visto que um decréscimo na germinação e no vigor e um acréscimo no número de botões germinativos apodrecidos e sementes mortas foram observados na temperatura de 20-30ºC.

Oviposition and predation of Pentilia egena mulsant (Coleoptera: Coccinellidae) in response to temperature

A espécie Pentilia egena Mulsant é importante predadora de cochonilas de carapaças que ocorrem em pomares citrícolas no Brasil. Para intensificar ainda mais este controle biológico, há necessidade de conhecimento dos aspectos bioecológicos deste predador para o aperfeiçoamento de sua criação massal. Este trabalho teve como objetivo estudar a influência da temperatura (19ºC, 24ºC e 29ºC) na oviposição de P. egena e na intensidade de predação de cochonilhas Aspidiotus nerii Bouché. A 29ºC observaram-se maiores médias de cochonilhas predadas e de ovos colocados, respectivamente, 5,1 ± 0,59 e 11,3 ± 0,19, que nas duas outras temperaturas. Entretanto, a viabilidade dos ovos foi inferior (52,86%), quando comparada àquela obtidas a 19ºC e 24ºC (78,10% e 74,07%, respectivamente). A temperatura não afetou o comportamento de oviposição deste coccinelídeo, sendo os ovos, preferencialmente, colocados sob a carapaça das cochonilhas já predadas.

Evaporative cooling and cutaneous surface temperature of Holstein cows in tropical conditions

Foram estudados os efeitos da temperatura cutânea (Ts) sobre a taxa de termólise por evaporação cutânea (Es) de vacas Holandesas cronicamente expostas ao sol, considerando a pigmentação do pelame. Dezesseis vacas puras de origem foram medidas quanto à evaporação e à temperatura cutâneas às 13 h, após 6 horas de exposição ao sol, no mesmo local (flanco, pescoço e glúteo) e considerando separadamente as malhas negras e as brancas. A evaporação cutânea foi medida por meio de cápsula ventilada. Nas áreas negras a taxa de sudação (138,9 ± 8,5 g.m-2.h-1), a taxa de termólise por evaporação cutânea (93,3 ± 5,7 W.m-2) e a temperatura da superfície cutânea (33,1 ± 0,2°C) foram maiores que nas áreas brancas (109,5 ± 9,7 g.m-2.h-1, 73,6 ± 6,5 W.m-2 e 32,6 ± 0,2°C, respectivamente). Há uma relação exponencial entre evaporação e temperatura cutâneas, que pode ser representada pela equação Es = 31,5+3,67 exp{(Ts-27,9)/2,19115}, com coeficiente de determinação r²=0,68. A taxa de termólise por evaporação cutânea permanece quase constante (cerca de 48 W.m-2) até que a temperatura cutânea atinge aproximadamente 31°C.

A DFT rationalization of the room temperature photoluminescence of Li2TiSiO5

Li2TiSiO5 powders were synthesized by the polymeric precursor method. The calcination temperatures were progressively increased until the complete crystallization of the phase occurring at 870 degreesC. For the first time, a strong photoluminescence was measured at room temperature with a 488 nm excitation wavelength for the non-crystalline samples. This photoluminescence in disordered phases has been interpreted by means of high-level quantum mechanical calculations based on density functional theory. Two periodic models have been used to represent the crystalline and disordered powders. They allowed to calculate electronic properties consistent with experimental data and to explain the relations between photoluminescence and structural disorder. (C) 2004 Elsevier B.V. All rights reserved.

Effect of temperature on the interaction between the nonionic surfactant C(12)E(5) and poly(ethylene oxide) investigated by dynamic light scattering and fluorescence methods

The interaction between the nonionic surfactant C(12)E(5) and a high molar mass (M = 5.94 x 10(5)) poly(ethylene oxide) (PEG) in aqueous solution has been examined as a function of temperature by dynamic light scattering and fluorescence methods over a broad concentration range. Clusters of small surfactant micelles form within the PEO coil, leading to its extension. The hydrodynamic radius of the complex increases strongly with temperature as well as with the concentrations of surfactant and polymer. At high concentrations of the surfactant, the coil/micellar cluster complex coexists with free C(12)E(5) micelles in the solution. Fluorescence quenching measurements show a moderate micellar growth from 155 to 203 monomers in PEO-free solutions of C(12)E(5) over a wide concentration range (0.02-2.5%) at 8 degrees C. Below 0.25% C(12)E(5), the average aggregation number (N) of the micelles is smaller in the presence of PEO than in its absence. However, N increases with increasing surfactant concentration up to a plateau value of about 270 at about 1.2% (ca. 30 mM) C(12)E(5). At high surfactant concentrations, N is larger in the presence of polymer than in its absence, a finding which is connected to a significant lowering of the clouding temperature due to the PEO at these compositions. Similar results of increasing aggregation number followed by a plateau were also found at a fixed concentration of surfactant (2.5%) and varied PEO.

An application of neural network technique to correct the dome temperature effects on pyrgeometer measurements

This work describes an application of a multilayer perceptron neural network technique to correct dome emission effects on longwave atmospheric radiation measurements carried out using an Eppley Precision Infrared Radiometer (PIR) pyrgeometer. It is shown that approximately 7-month-long measurements of dome and case temperatures and meteorological variables available in regular surface stations (global solar radiation, air temperature, and air relative humidity) are enough to train the neural network algorithm and correct the observed longwave radiation for dome temperature effects in surface stations with climates similar to that of the city of São Paulo, Brazil. The network was trained using data from 15 October 2003 to 7 January 2004 and verified using data, not present during the network-training period, from 8 January to 30 April 2004. The longwave radiation values generated by the neural network technique were very similar to the values obtained by Fairall et al., assumed here as the reference approach to correct dome emission effects in PIR pyrgeometers. Compared to the empirical approach the neural network technique is less limited to sensor type and time of day (allows nighttime corrections).

Photoluminescence at room temperature in amorphous SrTiO3 thin films obtained by chemical solution deposition

Intense photoluminescence in highly disordered strontium titanate amorphous thin films prepared by the polymeric precursor method was observed at room temperature (300 K). The luminescence spectra of SrTiO3 amorphous thin films at room temperature revealed an intense single-emission band in the visible region. X-ray absorption near edge structure was used to probe the local atomic structure of SrTiO3 amorphous and crystalline thin films. Photoluminescence intensity in the 535 nm range was found to be correlated with the presence of non-bridging oxygen defects. A discussion is presented of the nature of this photoluminescence, which may be related to the disordered structure in SrTiO3 amorphous thin films. (C) 2002 Elsevier B.V. B.V. All rights reserved.

ac conductivity and conduction mechanism of NaNbO3 semiconductor antiferroelectric ceramic: A relaxational approach at high temperature

The electric properties of the sodium niobate perovskite ceramic were investigated by impedance spectroscopy in the frequency range from 5 Hz to 13 MHz and from room temperature up to 1073 K, in a thermal cycle. Both capacitance and conductivity exhibit an anomaly at around 600 K as a function of the temperature and frequency. The electric conductivity as a function of angular frequency sigma(omega) follows the relation sigma(omega)=Aomega(s). The values of the exponent s lie in the range 0.15less than or equal tosless than or equal to0.44. These results were discussed considering the conduction mechanism as being a type of polaron hopping. (C) 2003 American Institute of Physics.

Temperature-dependent vortex motion in a square mesoscopic superconducting cylinder: Ginzburg-Landau calculations

In this work we investigate the dynamics of vortices in a square mesoscopic superconductor. As time evolves we show how the vortices are nucleated into the sample to form a multivortex, single vortex, and giant vortex states. We illustrate how the vortices move around at the transition fields before they accommodate into an equilibrium configuration. We also calculate the magnetization and the free energy as functions of the applied magnetic field for several values of temperature. In addition, we evaluate the upper critical field.