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Variable Temperatures (variable + temperature)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Pressure Effect Investigations on the Spin Crossover Systems{Fe[H2B(pz)2]2(bipy)} and {Fe[H2B(pz)2]2(phen)}

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006
Ana Galet
Abstract Pressure effect studies on the spin crossover behaviour of the mononuclear compounds {Fe[H2B(pz)2]2(bipy)}(1) and {Fe[H2B(pz)2]2(phen)}(2) have been performed in the range of 105 Pa,1.02 GPa at variable temperatures (100,310 K). Continuous spin transitions and displacement of its characteristic temperature has been observed for 1 with increasing pressure. Meanwhile the response of 2 under applied pressures is quite unexpected, and can only be understood in terms of a crystallographic phase transition or change in the bulk modulus of the compound. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Temperature,stress,strain trajectory modelling during thermo-mechanical fatigue

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 3 2006
M. NAGODE
ABSTRACT The isothermal strain-life approach is the most commonly used approach for determining fatigue damage, particularly when yielding occurs. Computationally it is extremely fast and generally requires elastic finite element analyses only. Therefore, it has been adapted for variable temperatures. Local temperature,stress,strain behaviour is modelled with an operator of the Prandtl type. The hysteresis loops are supposed to be stabilized and no creep is considered. The consequences of reversal point filtering are analysed. The approach is finally compared to several thermo-mechanical fatigue tests and the Skelton model. [source]

Thermal habitat of striped bass (Morone saxatilis) in coastal waters of northern Massachusetts, USA, during summer

FISHERIES OCEANOGRAPHY, Issue 5 2010
GARY A. NELSON
Abstract Striped bass, Morone saxatilis, were captured and released with temperature-measuring data storage tags in Salem Sound, Massachusetts, to collect data on their thermal preferences in coastal and marine waters and to identify environmental factors that may influence temperatures experienced during their summer residence. Striped bass recaptured during summer of 2006 (21 of 151 releases) experienced a wide range of temperatures (6.5,28.0°C) while at-large for 1,53 days. Overall mean temperature and standard deviation selected by striped bass recaptured in Salem Sound during the longest commonly-shared duration of time (3,12 July) were 17.8 and 3.57°C, respectively. Comparison of temperature data between fish and 13 vertical arrays in Salem Sound revealed that striped bass experienced higher and more variable temperatures, and that daily changes in temperature actually experienced were unrelated to daily changes in surrounding ambient temperature. Regular cyclical changes in temperature of all striped bass and vertical arrays were identified as influences of the local tide, which contributed about a 2°C change in temperature, on average, over the complete cycle. Most striped bass appeared to limit their activities to depths shallower than the lower limit of the thermocline, above which temperatures generally exceed 9.0°C in Salem Sound. Therefore, it is likely that the vertical distribution of striped bass is restricted by the low temperatures below this depth. An implication of this finding is that the spatial distribution of striped bass may be defined coarsely by knowledge of the distribution of temperature in coastal areas. [source]

Rational Design, Synthesis, and Optical Properties of Film-Forming, Near-Infrared Absorbing, and Fluorescent Chromophores with Multidonors and Large Heterocyclic Acceptors

CHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2009
Min Luo
Abstract A new series of film-forming, low-bandgap chromophores (1,a,b and 2,a,b) were rationally designed with aid of a computational study, and then synthesized and characterized. To realize absorption and emission above the 1000,nm wavelength, the molecular design focuses on lowering the LUMO level by fusing common heterocyclic units into a large conjugated core that acts an electron acceptor and increasing the charge transfer by attaching the multiple electron-donating groups at the appropriate positions of the acceptor core. The chromophores have bandgap levels of 1.27,0.71,eV, and accordingly absorb at 746,1003,nm and emit at 1035,1290,nm in solution. By design, the relatively high molecular weight (up to 2400,g,mol,1) and non-coplanar structure allow these near-infrared (NIR) chromophores to be readily spin-coated as uniform thin films and doped with other organic semiconductors for potential device applications. Doping with [6,6]-phenyl-C61 butyric acid methyl ester leads to a red shift in the absorption only for 1,a and 2,a. An interesting NIR electrochromism was found for 2,a, with absorption being turned on at 1034,nm when electrochemically switched (at 1000,mV) from its neutral state to a radical cation state. Furthermore, a large Stokes shift (256,318,nm) is also unique for this multidonor,acceptor type of chromophore, indicating a significant structural difference between the ground state and the excited state. Photoluminescence of the film of 2,a was further probed at variable temperatures and the results strongly suggest that the restriction of bond rotations certainly helps to diminish non-radiative decay and thus enhance the luminescence of these large chromophores. [source]