WorldWideScience

Sample records for strongly temperature-dependent part

  1. Strong temperature dependence of extraordinary magnetoresistance correlated to mobility in a two-contact device

    KAUST Repository

    Sun, Jian

    2012-02-21

    A two-contact extraordinary magnetoresistance (EMR) device has been fabricated and characterized at various temperatures under magnetic fields applied in different directions. Large performance variations across the temperature range have been found, which are due to the strong dependence of the EMR effect on the mobility. The device shows the highest sensitivity of 562ω/T at 75 K with the field applied perpendicularly. Due to the overlap between the semiconductor and the metal shunt, the device is also sensitive to planar fields but with a lower sensitivity of about 20 to 25% of the one to perpendicular fields. © 2012 The Japan Society of Applied Physics.

  2. Strong Temperature Dependence in the Reactivity of H 2 on RuO 2 (110)

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, Michael A.; Dahal, Arjun; Dohnálek, Zdenek; Lyubinetsky, Igor

    2016-08-04

    The ability of hydrogen to facilitate many types of heterogeneous catalysis starts with its adsorption. As such, understanding the temperature-dependence sticking of H2 is critical toward controlling and optimizing catalytic conditions in those cases where adsorption is rate-limiting. In this work, we examine the temperature-dependent sticking of H2/D2 to the clean RuO2(110) surface using the King & Wells molecular beam approach, temperature programmed desorption (TPD) and scanning tunneling microscopy (STM). We show that the sticking probability (molecular or dissociative) of H2/D2 on this surface is highly temperature-dependent, decreasing from ~0.4-0.5 below 25 K to effectively zero above 200 K. Both STM and TPD reveal that OH/OD formation is severely limited for adsorption temperatures above ~150 K. Previous literature reports of extensive surface hydroxylation from H2/D2 exposures at room temperature were most likely the result of inadvertent contamination brought about from dosing by chamber backfilling.

  3. Analytical Modelling and Optimization of the Temperature-Dependent Dynamic Mechanical Properties of Fused Deposition Fabricated Parts Made of PC-ABS

    Directory of Open Access Journals (Sweden)

    Omar Ahmed Mohamed

    2016-11-01

    Full Text Available Fused deposition modeling (FDM additive manufacturing has been intensively used for many industrial applications due to its attractive advantages over traditional manufacturing processes. The process parameters used in FDM have significant influence on the part quality and its properties. This process produces the plastic part through complex mechanisms and it involves complex relationships between the manufacturing conditions and the quality of the processed part. In the present study, the influence of multi-level manufacturing parameters on the temperature-dependent dynamic mechanical properties of FDM processed parts was investigated using IV-optimality response surface methodology (RSM and multilayer feed-forward neural networks (MFNNs. The process parameters considered for optimization and investigation are slice thickness, raster to raster air gap, deposition angle, part print direction, bead width, and number of perimeters. Storage compliance and loss compliance were considered as response variables. The effect of each process parameter was investigated using developed regression models and multiple regression analysis. The surface characteristics are studied using scanning electron microscope (SEM. Furthermore, performance of optimum conditions was determined and validated by conducting confirmation experiment. The comparison between the experimental values and the predicted values by IV-Optimal RSM and MFNN was conducted for each experimental run and results indicate that the MFNN provides better predictions than IV-Optimal RSM.

  4. Analytical Modelling and Optimization of the Temperature-Dependent Dynamic Mechanical Properties of Fused Deposition Fabricated Parts Made of PC-ABS

    Science.gov (United States)

    Mohamed, Omar Ahmed; Masood, Syed Hasan; Bhowmik, Jahar Lal

    2016-01-01

    Fused deposition modeling (FDM) additive manufacturing has been intensively used for many industrial applications due to its attractive advantages over traditional manufacturing processes. The process parameters used in FDM have significant influence on the part quality and its properties. This process produces the plastic part through complex mechanisms and it involves complex relationships between the manufacturing conditions and the quality of the processed part. In the present study, the influence of multi-level manufacturing parameters on the temperature-dependent dynamic mechanical properties of FDM processed parts was investigated using IV-optimality response surface methodology (RSM) and multilayer feed-forward neural networks (MFNNs). The process parameters considered for optimization and investigation are slice thickness, raster to raster air gap, deposition angle, part print direction, bead width, and number of perimeters. Storage compliance and loss compliance were considered as response variables. The effect of each process parameter was investigated using developed regression models and multiple regression analysis. The surface characteristics are studied using scanning electron microscope (SEM). Furthermore, performance of optimum conditions was determined and validated by conducting confirmation experiment. The comparison between the experimental values and the predicted values by IV-Optimal RSM and MFNN was conducted for each experimental run and results indicate that the MFNN provides better predictions than IV-Optimal RSM. PMID:28774019

  5. Temperature dependent anomalous statistics

    International Nuclear Information System (INIS)

    Das, A.; Panda, S.

    1991-07-01

    We show that the anomalous statistics which arises in 2 + 1 dimensional Chern-Simons gauge theories can become temperature dependent in the most natural way. We analyze and show that a statistic's changing phase transition can happen in these theories only as T → ∞. (author). 14 refs

  6. Measurements of temperature dependence of 'localized susceptibility'

    CERN Document Server

    Shiozawa, H; Ishii, H; Takayama, Y; Obu, K; Muro, T; Saitoh, Y; Matsuda, T D; Sugawara, H; Sato, H

    2003-01-01

    The magnetic susceptibility of some rare-earth compounds is estimated by measuring magnetic circular dichroism (MCD) of rare-earth 3d-4f absorption spectra. The temperature dependence of the magnetic susceptibility obtained by the MCD measurement is remarkably different from the bulk susceptibility in most samples, which is attributed to the strong site selectivity of the core MCD measurement.

  7. Temperature dependence of surface nanobubbles

    NARCIS (Netherlands)

    Berkelaar, R.P.; Seddon, James Richard Thorley; Zandvliet, Henricus J.W.; Lohse, Detlef

    2012-01-01

    The temperature dependence of nanobubbles was investigated experimentally using atomic force microscopy. By scanning the same area of the surface at temperatures from 51 °C to 25 °C it was possible to track geometrical changes of individual nanobubbles as the temperature was decreased.

  8. An important role of temperature dependent scattering time in understanding the high temperature thermoelectric behavior of strongly correlated system: La0.75Ba0.25CoO3.

    Science.gov (United States)

    Singh, Saurabh; Kumar, Devendra; Pandey, Sudhir K

    2017-03-15

    In the present work, we report the temperature dependent thermopower (α) behavior of La 0.75 Ba 0.25 CoO 3 compound in the temperature range 300-600 K. Using the Heikes formula, the estimated value of α corresponding to high-spin configuration of Co 3+ and Co 4+ ions is found to be  ∼16 [Formula: see text], which is close to the experimental value, ∼13 [Formula: see text], observed at  ∼600 K. The temperature dependent TE behavior of the compound is studied by combining the WIEN2K and BoltzTrap code. The self consistency field calculations show that the compound have ferromagnetic ground state structure. The electronic structure calculations give half metallic characteristic with a small gap of  ∼50 meV for down spin channel. The large and positive value for down spin channel is obtained due to the unique band structure shown by this spin channel. The temperature dependent relaxation time for both the spin-channel charge carriers is considered to study the thermopower data in temperature range 300-600 K. For evaluation of α, almost linear values of [Formula: see text] and a non-linear values of [Formula: see text] are taken into account. By taking the temperature dependent values of relaxation time for both the spin channels, the calculated values of α using two current model are found to be in good agreement with experimental values in the temperature range 300-600 K. At 300 K, the calculated value of electrical conductivity by using the same value of relaxation time, i.e. 0.1 [Formula: see text] 10 -14 seconds for spin-up and [Formula: see text] seconds for spin-dn channel, is found to be equal to the experimentally reported value.

  9. Temperature Dependence of Factors Controlling Isoprene Emissions

    Science.gov (United States)

    Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

    2009-01-01

    We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

  10. Temperature dependence of Brewster's angle.

    Science.gov (United States)

    Guo, Wei

    2018-01-01

    In this work, a dielectric at a finite temperature is modeled as an ensemble of identical atoms moving randomly around where they are trapped. Light reflection from the dielectric is then discussed in terms of atomic radiation. Specific calculation demonstrates that because of the atoms' thermal motion, Brewster's angle is, in principle, temperature-dependent, and the dependence is weak in the low-temperature limit. What is also found is that the Brewster's angle is nothing but a result of destructive superposition of electromagnetic radiation from the atoms.

  11. Temperature dependence of plastic scintillators

    Science.gov (United States)

    Peralta, L.

    2018-03-01

    Plastic scintillator detectors have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Several articles have reported undesired response dependencies on beam energy and temperature, which provides the motivation to determine appropriate correction factors. In this work, we studied the light yield temperature dependency of four plastic scintillators, BCF-10, BCF-60, BC-404, RP-200A and two clear fibers, BCF-98 and SK-80. Measurements were made using a 50 kVp X-ray beam to produce the scintillation and/or radioluminescence signal. The 0 to 40 °C temperature range was scanned for each scintillator, and temperature coefficients were obtained.

  12. (Alpha-) quenching temperature dependence in liquid scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Arnd; Lozza, Valentina; Krosigk, Belina von; Zuber, Kai [Institut fuer Kern- und Teilchenphysik, TU Dresden (Germany)

    2015-07-01

    Liquid scintillator (LS) is an effective and promising detector material, which is and will be used by many small and large scale experiments. In order to perform correct signal identification and background suppression, a very good knowledge of LS properties is crucial. One of those is the light yield from alpha particles in liquid scintillator. This light output strongly quenched, approx. 10 times compared to that of electrons, and has been precisely studied at room temperature for various LS. Big scintillator experiments, such as SNO+ and maybe future large scale detectors, will operate at different temperatures. While a strong temperature dependence is well known for solid state scintillators, due to the different scintillation process, a quenching temperature dependence in LS is usually assumed negligible. On the other hand, inconsistencies in between measurements are often explained by potential temperature effects. This study investigates LAB based liquid scintillator with an intrinsic, dissolved alpha emitter and its behaviour with temperature change. In a small, cooled and heated setup, a stabilized read-out with two PMTs is realised. First results are presented.

  13. Temperature dependent electronic conduction in semiconductors

    International Nuclear Information System (INIS)

    Roberts, G.G.; Munn, R.W.

    1980-01-01

    This review describes the temperature dependence of bulk-controlled electronic currents in semiconductors. The scope of the article is wide in that it contrasts conduction mechanisms in inorganic and organic solids and also single crystal and disordered semiconductors. In many experimental situations it is the metal-semiconductor contact or the interface between two dissimilar semiconductors that governs the temperature dependence of the conductivity. However, in order to keep the length of the review within reasonable bounds, these topics have been largely avoided and emphasis is therefore placed on bulk-limited currents. A central feature of electronic conduction in semiconductors is the concentrations of mobile electrons and holes that contribute to the conductivity. Various statistical approaches may be used to calculate these densities which are normally strongly temperature dependent. Section 1 emphasizes the relationship between the position of the Fermi level, the distribution of quantum states, the total number of electrons available and the absolute temperature of the system. The inclusion of experimental data for several materials is designed to assist the experimentalist in his interpretation of activation energy curves. Sections 2 and 3 refer to electronic conduction in disordered solids and molecular crystals, respectively. In these cases alternative approaches to the conventional band theory approach must be considered. For example, the velocities of the charge carriers are usually substantially lower than those in conventional inorganic single crystal semiconductors, thus introducing the possibility of an activated mobility. Some general electronic properties of these materials are given in the introduction to each of these sections and these help to set the conduction mechanisms in context. (orig.)

  14. Ferromagnetism and temperature-dependent electronic structure in metallic films

    International Nuclear Information System (INIS)

    Herrmann, T.

    1999-01-01

    In this work the influence of the reduced translational symmetry on the magnetic properties of thin itinerant-electron films and surfaces is investigated within the strongly correlated Hubbard model. Firstly, the possibility of spontaneous ferromagnetism in the Hubbard model is discussed for the case of systems with full translational symmetry. Different approximation schemes for the solution of the many-body problem of the Hubbard model are introduced and discussed in detail. It is found that it is vital for a reasonable description of spontaneous ferromagnetism to be consistent with exact results concerning the general shape of the single-electron spectral density in the limit of strong Coulomb interaction between the electrons. The temperature dependence of the ferromagnetic solutions is discussed in detail by use of the magnetization curves as well as the spin-dependent quasi particle spectrum. For the investigation of thin films and surfaces the approximation schemes for the bulk system have to be generalized to deal with the reduced translational symmetry. The magnetic behavior of thin Hubbard films is investigated by use of the layer dependent magnetization as a function of temperature as well as the thickness of the film. The Curie-temperature is calculated as a function of the film thickness. Further, the magnetic stability at the surface is discussed in detail. Here it is found that for strong Coulomb interaction the magnetic stability at finite temperatures is reduced at the surface compared to the inner layers. This observation clearly contradicts the well-known Stoner picture of band magnetism and can be explained in terms of general arguments which are based on exact results in the limit of strong Coulomb interaction. The magnetic behavior of the Hubbard films can be analyzed in detail by inspecting the local quasi particle density of states as well as the wave vector dependent spectral density. The electronic structure is found to be strongly spin

  15. Temperature dependence of coherence in transmon qubits

    Energy Technology Data Exchange (ETDEWEB)

    Schloer, Steffen; Braumueller, Jochen; Lukashenko, Oleksandr; Rotzinger, Hannes; Weides, Martin; Ustinov, Alexey V. [Physikalisches Institut, KIT, Karlsruhe (Germany); Sandberg, Martin; Vissers, Michael R.; Pappas, David P. [NIST, Boulder, CO (United States)

    2015-07-01

    Superconducting qubits are a promising field of research, not only with respect to quantum computing but also as highly sensitive detectors and due to the possibility of using them to study fundamental implications of quantum mechanics. The requirements for qubits that can be used as building blocks in a potential quantum computer are challenging. Modern superconducting qubits like the transmon are strong candidates for achieving these goals. The main challenge here is to increase the coherence of prepared quantum states. Here, we experimentally investigate the influence of temperature variation on relaxation and dephasing of a transmon qubit. Our goal is to understand decoherence mechanisms in material optimized circuits. Aiming at longer coherence, in this case peaking over 50 μs for T{sub 1} and T{sub 2}, our samples are fabricated at NIST using two different materials. Low-loss TiN was used for the shunt capacitance as well as the resonator, combined with shadow evaporated ultra-small Al-AlO{sub x}-Al Josephson junctions. We will present temperature-dependent data on qubit relaxation and dephasing times as well as power spectra. Our data will be compared to previously obtained temperature dependent data for other types of qubits.

  16. Temperature dependence of elastic properties of paratellurite

    International Nuclear Information System (INIS)

    Silvestrova, I.M.; Pisarevskii, Y.V.; Senyushenkov, P.A.; Krupny, A.I.

    1987-01-01

    New data are presented on the temperature dependence of the elastic wave velocities, elastic stiffness constants, and thermal expansion of paratellurite. It is shown that the external pressure appreciably influences the elastic properties of TeO 2 , especially the temperature dependence of the elastic modulus connected with the crystal soft mode. (author)

  17. Electronically induced nuclear transitions - temperature dependence and Rabi oscillations

    International Nuclear Information System (INIS)

    Niez, J.J.

    2002-01-01

    This paper deals with a nucleus electromagnetically coupled with the bound states of its electronic surroundings. It describes the temperature dependence of its dynamics and the onset of potential Rabi oscillations by means of a Master Equation. The latter is generalized in order to account for possible strong resonances. Throughout the paper the approximation schemes are discussed and tested. (authors)

  18. The temperature dependent amide I band of crystalline acetanilide

    International Nuclear Information System (INIS)

    Cruzeiro, Leonor; Freedman, Holly

    2013-01-01

    The temperature dependent anomalous peak in the amide I band of crystalline acetanilide is thought to be due to self-trapped states. On the contrary, according to the present model, the anomalous peak comes from the fraction of ACN molecules strongly hydrogen-bonded to a neighboring ACN molecule, and its intensity decreases because, on average, this fraction decreases as temperature increases. This model provides, for the first time, an integrated and theoretically consistent view of the temperature dependence of the full amide I band and a qualitative explanation of some of the features of nonlinear pump–probe experiments.

  19. The temperature dependent amide I band of crystalline acetanilide

    Energy Technology Data Exchange (ETDEWEB)

    Cruzeiro, Leonor [CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Physics Department, FCT, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Freedman, Holly [CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

    2013-10-01

    The temperature dependent anomalous peak in the amide I band of crystalline acetanilide is thought to be due to self-trapped states. On the contrary, according to the present model, the anomalous peak comes from the fraction of ACN molecules strongly hydrogen-bonded to a neighboring ACN molecule, and its intensity decreases because, on average, this fraction decreases as temperature increases. This model provides, for the first time, an integrated and theoretically consistent view of the temperature dependence of the full amide I band and a qualitative explanation of some of the features of nonlinear pump–probe experiments.

  20. The temperature dependent amide I band of crystalline acetanilide

    Science.gov (United States)

    Cruzeiro, Leonor; Freedman, Holly

    2013-10-01

    The temperature dependent anomalous peak in the amide I band of crystalline acetanilide is thought to be due to self-trapped states. On the contrary, according to the present model, the anomalous peak comes from the fraction of ACN molecules strongly hydrogen-bonded to a neighboring ACN molecule, and its intensity decreases because, on average, this fraction decreases as temperature increases. This model provides, for the first time, an integrated and theoretically consistent view of the temperature dependence of the full amide I band and a qualitative explanation of some of the features of nonlinear pump-probe experiments.

  1. Theory of temperature dependent photoemission spectrum of heavy fermion semiconductors

    International Nuclear Information System (INIS)

    Riseborough, P.S.

    1998-01-01

    The heavy fermion semiconductors are a class of strongly correlated materials, that at high temperatures show properties similar to those of heavy fermion materials, but at low temperatures show a cross-over into a semi-conducting state. The low temperature insulating state is characterized by an anomalously small energy gap, varying between 10 and 100 K. The smallness of the gap is attributed to the result of a many-body renormalization, and is temperature dependent. The temperature dependence of the electronic spectral density of states is calculated, using the Anderson lattice model at half filling. The spectrum is calculated to second order in 1/N, where N is the degeneracy of the 'f' orbitals, using a slave boson technique. The system is an indirect gap semi-conductor, with an extremely temperature dependent electronic spectral density A(k, ω). The indirect gap is subject to a temperature dependent many-body renormalization, and leads to a sharp temperature dependent structure in the angle resolved photo-emission spectrum at the indirect threshold. The theoretical predictions are compared with experimental observations on FeSi. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

  2. Temperature dependence of nuclear surface properties

    International Nuclear Information System (INIS)

    Campi, X.; Stringari, S.

    1982-01-01

    Thermal properties of nuclear surface are investigated in a semi-infinite medium. Explicit analytical expression are given for the temperature dependence of surface thickness, surface energy and surface free energy. In this model the temperature effects depend critically on the nuclear incompressibility and on the shape of the effective mass at the surface. To illustrate the relevance of these effects we made an estimate of the temperature dependence of the fission barrier height. (orig.)

  3. Evaluation of temperature dependent neutron resonance integrals

    International Nuclear Information System (INIS)

    Menon, S.V.G.; Sahni, D.C.

    1975-01-01

    The Fourier transform method is extended for evaluating temperature dependent resonance integrals and Doppler coefficients. With the temperature dependent cross-sections, the slowing-down equation is transformed into a Fredholm integral equation of second kind. A method of solution is presented using the familiar Gauss-Hermite quadrature formulae. As a byproduct of the above technique, a fast and accurate method for computing the resonance integral J-function is given. (orig.) [de

  4. Temperature dependence of postmortem MR quantification for soft tissue discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Zech, Wolf-Dieter; Schwendener, Nicole; Jackowski, Christian [University of Bern, From the Institute of Forensic Medicine, Bern (Switzerland); Persson, Anders; Warntjes, Marcel J. [University of Linkoeping, The Center for Medical Image Science and Visualization (CMIV), Linkoeping (Sweden)

    2015-08-15

    To investigate and correct the temperature dependence of postmortem MR quantification used for soft tissue characterization and differentiation in thoraco-abdominal organs. Thirty-five postmortem short axis cardiac 3-T MR examinations were quantified using a quantification sequence. Liver, spleen, left ventricular myocardium, pectoralis muscle and subcutaneous fat were analysed in cardiac short axis images to obtain mean T1, T2 and PD tissue values. The core body temperature was measured using a rectally inserted thermometer. The tissue-specific quantitative values were related to the body core temperature. Equations to correct for temperature differences were generated. In a 3D plot comprising the combined data of T1, T2 and PD, different organs/tissues could be well differentiated from each other. The quantitative values were influenced by the temperature. T1 in particular exhibited strong temperature dependence. The correction of quantitative values to a temperature of 37 C resulted in better tissue discrimination. Postmortem MR quantification is feasible for soft tissue discrimination and characterization of thoraco-abdominal organs. This provides a base for computer-aided diagnosis and detection of tissue lesions. The temperature dependence of the T1 values challenges postmortem MR quantification. Equations to correct for the temperature dependence are provided. (orig.)

  5. Temperature dependence of postmortem MR quantification for soft tissue discrimination

    International Nuclear Information System (INIS)

    Zech, Wolf-Dieter; Schwendener, Nicole; Jackowski, Christian; Persson, Anders; Warntjes, Marcel J.

    2015-01-01

    To investigate and correct the temperature dependence of postmortem MR quantification used for soft tissue characterization and differentiation in thoraco-abdominal organs. Thirty-five postmortem short axis cardiac 3-T MR examinations were quantified using a quantification sequence. Liver, spleen, left ventricular myocardium, pectoralis muscle and subcutaneous fat were analysed in cardiac short axis images to obtain mean T1, T2 and PD tissue values. The core body temperature was measured using a rectally inserted thermometer. The tissue-specific quantitative values were related to the body core temperature. Equations to correct for temperature differences were generated. In a 3D plot comprising the combined data of T1, T2 and PD, different organs/tissues could be well differentiated from each other. The quantitative values were influenced by the temperature. T1 in particular exhibited strong temperature dependence. The correction of quantitative values to a temperature of 37 C resulted in better tissue discrimination. Postmortem MR quantification is feasible for soft tissue discrimination and characterization of thoraco-abdominal organs. This provides a base for computer-aided diagnosis and detection of tissue lesions. The temperature dependence of the T1 values challenges postmortem MR quantification. Equations to correct for the temperature dependence are provided. (orig.)

  6. Temperature-dependent errors in nuclear lattice simulations

    International Nuclear Information System (INIS)

    Lee, Dean; Thomson, Richard

    2007-01-01

    We study the temperature dependence of discretization errors in nuclear lattice simulations. We find that for systems with strong attractive interactions the predominant error arises from the breaking of Galilean invariance. We propose a local 'well-tempered' lattice action which eliminates much of this error. The well-tempered action can be readily implemented in lattice simulations for nuclear systems as well as cold atomic Fermi systems

  7. Investigation Of Temperature Dependent Characteristics Of ...

    African Journals Online (AJOL)

    The structure, magnetization and magnetostriction of Laves phase compound TbCo2 were investigated by temperature dependent high resolution neutron powder diffraction. The compound crystallizes in the cubic Laves phase C15 structure above its Curie temperature, TC and exhibits a rhombohedral distortion (space ...

  8. Temperature Dependent Models of Semiconductor Devices for ...

    African Journals Online (AJOL)

    The paper presents an investigation of the temperature dependent model of a diode and bipolar transistor built-in to the NAP-2 program and comparison of these models with experimentally measured characteristics of the BA 100 diode and BC 109 transistor. The detail of the modelling technique has been discussed and ...

  9. Temperature dependence of PZT film optical properties

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Jastrabík, Lubomír; Suchaneck, G.; Gerlach, G.

    11-12, - (2001), s. 352-354 ISSN 0447-6441 R&D Projects: GA ČR GA202/00/1425; GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010914 Keywords : refractive index profile * PZT film * temperature dependence of optical properties Subject RIV: BH - Optics, Masers, Lasers

  10. Temperature dependence of microwave oscillations in magnetic tunnel junctions with a perpendicularly magnetized free layer

    International Nuclear Information System (INIS)

    Guo, Peng; Feng, Jiafeng; Wei, Hongxiang; Han, Xiufeng; Fang, Bin; Zhang, Baoshun; Zeng, Zhongming

    2015-01-01

    We experimentally study the temperature dependence of the spin-transfer-torque-induced microwave oscillations in MgO-based magnetic tunnel junction nanopillars with a perpendicularly magnetized free layer. We demonstrate that the oscillation frequency increases rapidly with decreasing temperature, which is mainly ascribed to the temperature dependence of both the saturation magnetization and the perpendicular magnetic anisotropy. We also find that a strong temperature dependence of the output power while a nonmonotonic temperature dependence of spectral linewidth are maintained for a constant dc bias in measured temperature range. Possible mechanisms leading to the different dependences of oscillation frequency, output power, and linewidth are discussed

  11. Temperature dependence of radiation chemistry of polymers

    International Nuclear Information System (INIS)

    Garrett, R.W.; Hill, D.J.T.; Le, T.T.; Milne, K.A.; O'Donnell, J.H.; Perera, S.M.C.; Pomery, P.J.

    1990-01-01

    Chemical reactions which occur during radiolysis of polymers usually show an increase in rate with increasing temperature that can be described by an Arrhenius relationship. The magnitude of the activation energy can vary widely and is affected by physical, as well as chemical, factors. Different reaction rates may be expected in crystalline and amorphous morphologies, and in glassy and rubbery regions. The temperature dependence of radiolysis reactions can be expected to show discontinuities at the glass and melting transitions, T g and T m . The ceiling temperature, T c , for polymerization/depolymerization will also affect the rate of degradation, especially for depropagation to monomer. The temperature for this effect depends on the molecular structure of the polymer. The temperature dependence of free radical reactions can be studied by cryogenic trapping and ESR spectroscopy during thermal profiling. Increased degradation rates at high dose rates can be due to increased temperatures resulting from energy absorption

  12. Temperature dependence of giant dipole resonance width

    International Nuclear Information System (INIS)

    Vdovin, A.I.; Storozhenko, A.N.

    2005-01-01

    The quasiparticle-phonon nuclear model extended to finite temperature within the framework of the thermo field dynamics is applied to calculate a temperature dependence of the spreading width Γ d own of a giant dipole resonance. Numerical calculations are made for 12S n and 208 Pb nuclei. It is found that the width Γ d own increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones existing in the literature

  13. Temperature dependence of radiation effects in polyethylene

    International Nuclear Information System (INIS)

    Wu, G; Katsumura, Y.; Kudoh, H.; Morita, Y.; Seguchi, T.

    2000-01-01

    Temperature dependence of crosslinking and gas evolution under γ-irradiation was studied for high-density and low-density polyethylene samples in the 30-360degC range. It was found that crosslinking was the predominant process up to 300degC and the gel point decreased with increasing temperature. At above 300degC, however, the gel fraction at a given dose decreased rapidly with temperature and the action of radiation turned to enhance polyethylene degradation. Yields of H 2 and hydrocarbon gases increased with temperature and the compositions of hydrocarbons were dose dependent. (author)

  14. Modeling the temperature dependence of thermophysical properties: Study on the effect of temperature dependence for RFA.

    Science.gov (United States)

    Watanabe, Hiroki; Kobayashi, Yo; Hashizume, Makoto; Fujie, Masakatsu G

    2009-01-01

    Radio frequency ablation (RFA) has increasingly been used over the past few years and RFA treatment is minimally invasive for patients. However, it is difficult for operators to control the precise formation of coagulation zones due to inadequate imaging modalities. With this in mind, an ablation system using numerical simulation to analyze the temperature distribution of the organ is needed to overcome this deficiency. The objective of our work is to develop a temperature dependent thermophysical liver model. First, an overview is given of the development of the thermophysical liver model. Second, a simulation to evaluate the effect of temperature dependence of the thermophysical properties of the liver is explained. Finally, the result of the simulation, which indicated that the temperature dependence of thermophysical properties accounts for temperature differences influencing the accuracy of RFA treatment is described.

  15. Correction of SiPM temperature dependencies

    International Nuclear Information System (INIS)

    Kaplan, A.

    2009-01-01

    The performance of a high granular analogue hadronic calorimeter (AHCAL) using scintillator tiles with built-in Silicon Photomultiplier (SiPM) readout is reported. A muon beam is used for the minimum ionizing particle (MIP) based calibration of the single cells. The calibration chain including corrections for the non-linearity of the SiPM is presented. The voltage and temperature dependencies of the SiPM signal have been investigated using the versatile LED system of the AHCAL. Monitoring and correction methods are discussed. Measurements from the operation 2006 and 2007 at the CERN SPS test beam and data provided by the Institute for Theoretical and Experimental Physics (ITEP) in Moscow are compared.

  16. Temperature dependency in motor skill learning.

    Science.gov (United States)

    Immink, Maarten A; Wright, David L; Barnes, William S

    2012-01-01

    The present study investigated the role of temperature as a contextual condition for motor skill learning. Precision grip task training occurred while forearm cutaneous temperature was either heated (40-45 °C) or cooled (10-15 °C). At test, temperature was either reinstated or changed. Performance was comparable between training conditions while at test, temperature changes decreased accuracy, especially after hot training conditions. After cold training, temperature change deficits were only evident when concurrent force feedback was presented. These findings are the first evidence of localized temperature dependency in motor skill learning in humans. Results are not entirely accounted for by a context-dependent memory explanation and appear to represent an interaction of neuromuscular and sensory processes with the temperature present during training and test.

  17. Temperature dependent quasiparticle renormalization in nickel metal

    Energy Technology Data Exchange (ETDEWEB)

    Ovsyannikov, Ruslan; Sanchez-Barriga, Jaime; Fink, Joerg; Duerr, Hermann A. [Helmholtz Zentrum Berlin (Germany). BESSY II

    2009-07-01

    One of the fundamental consequences of electron correlation effects is that the bare particles in solids become 'dressed', i.e. they acquire an increased effective mass and a lifetime. We studied the spin dependent quasiparticle band structure of Ni(111) with high resolution angle resolved photoemission spectroscopy. At low temperatures (50 K) a renormalization of quasiparticle energy and lifetime indicative of electron-phonon coupling is observed in agreement with literature. With increasing temperature we observe a decreasing quasiparticle lifetime at the Fermi level for all probed minority spin bands as expected from electron phonon coupling. Surprisingly the majority spin states behave differently. We actually observe a slightly increased lifetime at room temperature. The corresponding increase in Fermi velocity points to a temperature dependent reduction of the majority spin quasiparticle renormalization.

  18. Temperature Dependent Wire Delay Estimation in Floorplanning

    DEFF Research Database (Denmark)

    Winther, Andreas Thor; Liu, Wei; Nannarelli, Alberto

    2011-01-01

    Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability. In this w......Due to large variations in temperature in VLSI circuits and the linear relationship between metal resistance and temperature, the delay through wires of the same length can be different. Traditional thermal aware floorplanning algorithms use wirelength to estimate delay and routability....... In this work, we show that using wirelength as the evaluation metric does not always produce a floorplan with the shortest delay. We propose a temperature dependent wire delay estimation method for thermal aware floorplanning algorithms, which takes into account the thermal effect on wire delay. The experiment...

  19. Liquid-filled ionization chamber temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Franco, L. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain)]. E-mail: luciaff@usc.es; Gomez, F. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Iglesias, A. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pardo, J. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pazos, A. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Pena, J. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain); Zapata, M. [Dpto. de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, Campus Sur S/N, 15782 Santiago de Compostela (Spain)

    2006-05-10

    Temperature and pressure corrections of the read-out signal of ionization chambers have a crucial importance in order to perform high-precision absolute dose measurements. In the present work the temperature and pressure dependences of a sealed liquid isooctane filled ionization chamber (previously developed by the authors) for radiotherapy applications have been studied. We have analyzed the thermal response of the liquid ionization chamber in a {approx}20 deg. C interval around room temperature. The temperature dependence of the signal can be considered linear, with a slope that depends on the chamber collection electric field. For example, a relative signal slope of 0.27x10{sup -2}K{sup -1} for an operation electric field of 1.67x10{sup 6}Vm{sup -1} has been measured in our detector. On the other hand, ambient pressure dependence has been found negligible, as expected for liquid-filled chambers. The thermal dependence of the liquid ionization chamber signal can be parametrized within the Onsager theory on initial recombination. Considering that changes with temperature of the detector response are due to variations in the free ion yield, a parametrization of this dependence has been obtained. There is a good agreement between the experimental data and the theoretical model from the Onsager framework.

  20. Temperature-dependent ion beam mixing

    International Nuclear Information System (INIS)

    Rehn, L.E.; Alexander, D.E.

    1993-08-01

    Recent work on enhanced interdiffusion rates during ion-beam mixing at elevated temperatures is reviewed. As discussed previously, expected increase in ion-beam mixing rates due to 'radiation-enhanced diffusion' (RED), i.e. the free migration of isolated vacancy and interstitial defects, is well documented in single-crystal specimens in the range of 0.4 to 0.6 of absolute melting temperature. In contrast, the increase often observed at somewhat lower temperatures during ion-beam mixing of polycrystalline specimens is not well understood. However, sufficient evidence is available to show that this increase reflects intracascade enhancement of a thermally-activated process that also occurs without irradiation. Recent evidence is presented which suggests that this process is Diffusion-induced Grain-Boundary Migration (DIGM). An important complementary conclusion is that because ion-beam mixing in single-crystal specimens exhibits no significant temperature dependence below that of RED, models that invoke only irradiation-specific phenomena, e.g., cascade-overlap, thermal-spikes, or liquid-diffusion, and hence which predict no difference in mixing behavior between single- or poly-crystalline specimens, cannot account for the existing results

  1. Temperature dependence in magnetic particle imaging

    Science.gov (United States)

    Wells, James; Paysen, Hendrik; Kosch, Olaf; Trahms, Lutz; Wiekhorst, Frank

    2018-05-01

    Experimental results are presented demonstrating how temperature can influence the dynamics of magnetic nanoparticles (MNPs) in liquid suspension, when exposed to alternating magnetic fields in the kilohertz frequency range. The measurements used to probe the nanoparticle systems are directly linked to both the emerging biomedical technique of magnetic particle imaging (MPI), and to the recently proposed concept of remote nanoscale thermometry using MNPs under AC field excitation. Here, we report measurements on three common types of MNPs, two of which are currently leading candidates for use as tracers in MPI. Using highly-sensitive magnetic particle spectroscopy (MPS), we demonstrate significant and divergent thermal dependences in several key measures used in the evaluation of MNP dynamics for use in MPI and other applications. The temperature range studied was between 296 and 318 Kelvin, making our findings of particular importance for MPI and other biomedical technologies. Furthermore, we report the detection of the same temperature dependences in measurements conducted using the detection coils within an operational preclinical MPI scanner. This clearly shows the importance of considering temperature during MPI development, and the potential for temperature-resolved MPI using this system. We propose possible physical explanations for the differences in the behaviors observed between the different particle types, and discuss our results in terms of the opportunities and concerns they raise for MPI and other MNP based technologies.

  2. Temperature dependent dynamic susceptibility calculations for itinerant ferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, J. F.

    1980-10-01

    Inelastic neutron scattering experiments have revealed a variety of interesting and unusual phenomena associated with the spin dynamics of the 3-d transition metal ferromagnets nickel and iron. An extensive series of calculations based on the itinerant electron formalism has demonstrated that the itinerant model does provide an excellent quantitative as well as qualitative description of the measured spin dynamics of both nickel and iron at low temperatures. Recent angular photo emission experiments have indicated that there is a rather strong temperature dependence of the electronic spin-splitting which, from relatively crude arguments, appears to be inconsistent with neutron scattering results. In order to investigate this point and also the origin of spin-wave renormalization, a series of calculations of the dynamic susceptibility of nickel and iron has been undertaken. The results of these calculations indicate that a discrepancy exists between the interpretations of neutron and photoemission experimental results regarding the temperature dependence of the spin-splitting of the electronic energy bands.

  3. Temperature dependence of gafchromic MD-55 dosimeter

    International Nuclear Information System (INIS)

    Klassen, Norman V.; Zwan, Len van der; Cygler, Joanna

    1997-01-01

    Objective: Gafchromic MD-55 is a fairly new, thin film dosimeter that develops a blue color (λ max = 676 nm) when irradiated with ionizing radiation. The increase in absorbance is nearly proportional to the absorbed dose. MD-55 can be used for high precision dosimetry if care is taken to assure reproducible film orientation in the spectrophotometer as well as temperature control during both irradiation and reading. In order to achieve the maximum sensitivity of this dosimeter the readings of the optical density should be taken at λ max . It was reported for another type of Gafchromic film (DM-1260), that both λ max and ε max decrease with an increase in the temperature of the spectrophotometer. The purpose of this study was to characterize the reading temperature dependence of the new type of Gafchromic film available on the market and to find optimal conditions for using it for high precision dosimetry. Materials and Methods: Irradiations were carried out using 60 Co gamma rays from an Eldorado irradiator. The dosimeters were sandwiched in a lucite phantom with 4.4 mm build-up and irradiated in the center of a 10 cm x 10 cm field at 1 meter from the source. The temperature during irradiations was 22 deg. C. The dose rate was about 0.68 Gy/min. Measurements of optical density were made using a Cary 210 spectrophotometer. A bandpass of 3.5 nm was used. The temperature of the baseplate of the sample holder was regulated to +/-0.05 deg. C and measured by a probe lying on the baseplate. In all cases, values of OD were only recorded after they had come to a constant value, which was reached within 5 minutes of inserting the dosimeter into the sample chamber of the spectrophotometer. Results: The temperature dependence of the OD at 676 nm was measured in 2 studies using 6 dosimeters that had received 0, 1.0, 3.5, 6.2, 14.5 Gy. Readings were taken at 7 temperatures between 18.8 and 28.1 deg. C. By returning to the initial temperature several hours later, it was found

  4. On the temperature dependence of the excess resistivity in dilute volatile alloys

    International Nuclear Information System (INIS)

    Uray, L.; Vicsek, T.

    1978-01-01

    In recrystallized wires of many important refractory alloys, an appreciable part of the temperature dependence of the measured excess resistivity is related to the radial distribution of the volatile solutes (extrinsic temperature dependence). Both the extrinsic and the intrinsic part of the temperature dependence of the excess resistivity have been determined for dilute WFe, WCo and WRe alloys, by measuring the resistance as a function of temperature and the thickness of layers removed by electrothinning. In this way the parameters of the evaporation profiles were also determined. In the surface region at low temperatures the length scale of the inhomogeneity is comparable to the mean-free path. Therefore, the observed extrinsic temperature dependence of the excess resistivity was calculated directly from the Boltzmann equation. The WCo alloy is a Kondo system, since its resistivity shows a minimum a 20 K. (author)

  5. Pipeline flow of heavy oil with temperature-dependent viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Maza Quinones, Danmer; Carvalho, Marcio da Silveira [Pontifical Catholic University of Rio de Janeiro (PUC-Rio), RJ (Brazil). Dept. of Mechanical Engineering], E-mail: msc@puc-rio.br

    2010-07-01

    The heavy oil produced offshore needs to be transported through pipelines between different facilities. The pipelines are usually laid down on the seabed and are submitted to low temperatures. Although heavy oils usually present Newtonian behavior, its viscosity is a strong function of temperature. Therefore, the prediction of pressure drops along the pipelines should include the solution of the energy equation and the dependence of viscosity to temperature. In this work, an asymptotic model is developed to study this problem. The flow is considered laminar and the viscosity varies exponentially with temperature. The model includes one-dimensional equations for the temperature and pressure distribution along the pipeline at a prescribed flow rate. The solution of the coupled differential equation is obtained by second-order finite difference. Results show a nonlinear behavior as a result of coupled interaction between the velocity, temperature, and temperature dependent material properties. (author)

  6. Heat experiment design to estimate temperature dependent thermal properties

    International Nuclear Information System (INIS)

    Romanovski, M

    2008-01-01

    Experimental conditions are studied to optimize transient experiments for estimating temperature dependent thermal conductivity and volumetric heat capacity. A mathematical model of a specimen is the one-dimensional heat equation with boundary conditions of the second kind. Thermal properties are assumed to vary nonlinearly with temperature. Experimental conditions refer to the thermal loading scheme, sampling times and sensor location. A numerical model of experimental configurations is studied to elicit the optimal conditions. The numerical solution of the design problem is formulated on a regularization scheme with a stabilizer minimization without a regularization parameter. An explicit design criterion is used to reveal the optimal sensor location, heating duration and flux magnitude. Results obtained indicate that even the strongly nonlinear experimental design problem admits the aggregation of its solution and has a strictly defined optimal measurement scheme. Additional region of temperature measurements with allowable identification error is revealed.

  7. Temperature Dependence of the Viscosity of Isotropic Liquids

    Science.gov (United States)

    Jadzyn, J.; Czechowski, G.; Lech, T.

    1999-04-01

    Temperature dependence of the shear viscosity measured for isotropic liquids belonging to the three homologous series: 4-(trans-4'-n-alkylcyclohexyl) isothiocyanatobenzenes (Cn H2n+1 CyHx Ph NCS; nCHBT, n=0-12), n-alkylcyanobiphenyls (CnH2n+1 Ph Ph CN; nCB, n=2-12) and 1,n-alkanediols (HO(CH2)nOH; 1,nAD, n=2-10) were analysed with the use of Arrhenius equation and its two modifications: Vogel--Fulcher and proposed in this paper. The extrapolation of the isothermal viscosity of 1,n-alkanediols (n=2-10) to n=1 leads to an interesting conclusion concerning the expected viscosity of methanediol, HOCH2OH, the compound strongly unstable in a pure state.

  8. Sample holder for studying temperature dependent particle guiding

    International Nuclear Information System (INIS)

    Bereczky, R.J.; Toekesi, K.; Kowarik, G.; Aumayr, F.

    2011-01-01

    Complete text of publication follows. The so called guiding effect is a complex process involving the interplay of a large number of charged particles with a solid. Although many research groups joined this field and carried out various experiments with insulator capillaries many details of the interactions are still unknown. We investigated the temperature dependence of the guiding since it opens new possibilities both for a fundamental understanding of the guiding phenomenon and for applications. For the temperature dependent guiding experiments a completely new heatable sample holder was designed. We developed and built such a heatable sample holder to make accurate and reproducible studies of the temperature dependence of the ion guiding effect possible. The target holder (for an exploded view see Fig. 1) consists of two main parts, the front and the back plates. The two plates of the sample holder, which function as an oven, are made of copper. These parts surround the capillary in order to guarantee a uniform temperature along the whole tube. The temperature of the copper parts is monitored by a K-Type thermocouple. Stainless steel coaxial heaters surrounding the oven are used for heating. The heating power up to a few watts is regulated by a PID controller. Cooling of the capillary is achieved by a copper feed-through connected to a liquid nitrogen bath outside the UHV chamber. This solution allows us to change the temperature of the sample from -30 deg C up to 90 deg C. Our experiments with this newly developed temperature regulated capillary holder show that the glass temperature (i.e. conductivity) can be used to control the guiding properties of the glass capillary and adjust the conditions from guiding at room temperature to simple geometrical transmission at elevated temperatures. This holds the promise to investigate the effect of conductivity on particle transport (build-up and removal of charge patches) through capillaries in more details

  9. Temperature dependency of silicon structures for magnetic field gradient sensing

    Science.gov (United States)

    Dabsch, Alexander; Rosenberg, Christoph; Stifter, Michael; Keplinger, Franz

    2018-02-01

    This work describes the temperature dependence of two sensors for magnetic field gradient sensors and demonstrates a structure to compensate for the drift of resonance frequency over a wide temperature range. The temperature effect of the sensing element is based on internal stresses induced by the thermal expansion of material, therefore FEM is used to determine the change of the eigenvalues of the sensing structure. The experimental setup utilizes a Helmholtz coil system to generate the magnetic field and to excite the MEMS structure with Lorentz forces. The MEMS structure is placed on a plate heated with resistors and cooled by a Peltier element to control the plate temperature. In the second part, we describe how one can exploit temperature sensitivity for temperature measurements and we show the opportunity to include the temperature effect to increase the sensitivity of single-crystal silicon made flux density gradient sensors.

  10. Temperature-dependent cross sections for meson-meson nonresonant reactions in hadronic matter

    International Nuclear Information System (INIS)

    Zhang Yiping; Xu Xiaoming; Ge Huijun

    2010-01-01

    We present a potential of which the short-distance part is given by one gluon exchange plus perturbative one- and two-loop corrections and of which the large-distance part exhibits a temperature-dependent constant value. The Schroedinger equation with this temperature-dependent potential yields a temperature dependence of the mesonic quark-antiquark relative-motion wave function and of meson masses. The temperature dependence of the potential, the wave function and the meson masses brings about temperature dependence of cross sections for the nonresonant reactions ππ→ρρ for I=2, KK→K*K* for I=1, KK*→K*K* for I=1, πK→ρK* for I=3/2, πK*→ρK* for I=3/2, ρK→ρK* for I=3/2 and πK*→ρK for I=3/2. As the temperature increases, the rise or fall of peak cross sections is determined by the increased radii of initial mesons, the loosened bound states of final mesons, and the total-mass difference of the initial and final mesons. The temperature-dependent cross sections and meson masses are parametrized.

  11. Temperature dependence of grain boundary free energy and elastic constants

    International Nuclear Information System (INIS)

    Foiles, Stephen M.

    2010-01-01

    This work explores the suggestion that the temperature dependence of the grain boundary free energy can be estimated from the temperature dependence of the elastic constants. The temperature-dependent elastic constants and free energy of a symmetric Σ79 tilt boundary are computed for an embedded atom method model of Ni. The grain boundary free energy scales with the product of the shear modulus times the lattice constant for temperatures up to about 0.75 the melting temperature.

  12. A Temperature-Dependent Hysteresis Model for Relaxor Ferroelectric Compounds

    National Research Council Canada - National Science Library

    Raye, Julie K; Smith, Ralph C

    2004-01-01

    This paper summarizes the development of a homogenized free energy model which characterizes the temperature-dependent hysteresis and constitutive nonlinearities inherent to relaxor ferroelectric materials...

  13. Power-law temperature dependence of the inelastic-scattering rate in disordered superconductors

    International Nuclear Information System (INIS)

    Devereaux, T.P.; Belitz, D.

    1991-01-01

    We present a theory of the quasiparticle inelastic lifetime τ in in disordered superconducting films. We find that both the Coulomb and the electron-phonon contribution to τ in -1 are enhanced by disorder, and that for reasonably strong electron-phonon coupling the latter is dominant. In contrast to clean superconductors, the scattering rate is larger than the recombination rate at all temperatures. This leads to a power-law temperature dependence of τ in -1 , in agreement with experimental observations. The theory quantitatively accounts for the magnitude, disorder dependence, and temperature dependence of τ in measured in recent experiments

  14. Temperature dependent transport characteristics of graphene/n-Si diodes

    International Nuclear Information System (INIS)

    Parui, S.; Ruiter, R.; Zomer, P. J.; Wojtaszek, M.; Wees, B. J. van; Banerjee, T.

    2014-01-01

    Realizing an optimal Schottky interface of graphene on Si is challenging, as the electrical transport strongly depends on the graphene quality and the fabrication processes. Such interfaces are of increasing research interest for integration in diverse electronic devices as they are thermally and chemically stable in all environments, unlike standard metal/semiconductor interfaces. We fabricate such interfaces with n-type Si at ambient conditions and find their electrical characteristics to be highly rectifying, with minimal reverse leakage current (<10 −10  A) and rectification of more than 10 6 . We extract Schottky barrier height of 0.69 eV for the exfoliated graphene and 0.83 eV for the CVD graphene devices at room temperature. The temperature dependent electrical characteristics suggest the influence of inhomogeneities at the graphene/n-Si interface. A quantitative analysis of the inhomogeneity in Schottky barrier heights is presented using the potential fluctuation model proposed by Werner and Güttler

  15. Temperature dependence of the two photon absorption in indium arsenide

    International Nuclear Information System (INIS)

    Berryman, K.W.; Rella, C.W.

    1995-01-01

    Nonlinear optical processes in semiconductors have long been a source of interesting physics. Two photon absorption (TPA) is one such process, in which two photons provide the energy for the creation of an electron-hole pair. Researchers at other FEL centers have studied room temperature TPA in InSb, InAs, and HgCdTe. Working at the Stanford Picosecond FEL Center, we have extended and refined this work by measuring the temperature dependence of the TPA coefficient in InAs over the range from 80 to 350 K at four wavelengths: 4.5, 5.06, 6.01, and 6.3 microns. The measurements validate the functional dependence of recent band structure calculations with enough precision to discriminate parabolic from non-parabolic models, and to begin to observe smaller effects, such as contributions due to the split-off band. These experiments therefore serve as a strong independent test of the Kane band theory, as well as providing a starting point for detailed observations of other nonlinear absorption mechanisms

  16. Temperature dependence of single-particle properties in nuclear matter

    International Nuclear Information System (INIS)

    Zuo, W.; Lu, G.C.; Li, Z.H.; Lombardo, U.; Schulze, H.-J.

    2006-01-01

    The single-nucleon potential in hot nuclear matter is investigated in the framework of the Brueckner theory by adopting the realistic Argonne V 18 or Nijmegen 93 two-body nucleon-nucleon interaction supplemented by a microscopic three-body force. The rearrangement contribution to the single-particle potential induced by the ground state correlations is calculated in terms of the hole-line expansion of the mass operator and provides a significant repulsive contribution in the low-momentum region around and below the Fermi surface. Increasing temperature leads to a reduction of the effect, while increasing density makes it become stronger. The three-body force suppresses somewhat the ground state correlations due to its strong short-range repulsion, increasing with density. Inclusion of the three-body force contribution results in a quite different temperature dependence of the single-particle potential at high enough densities as compared to that adopting the pure two-body force. The effects of three-body force and ground state correlations on the nucleon effective mass are also discussed

  17. Temperature dependence of heat sensitization and thermotolerance induction with ethanol

    International Nuclear Information System (INIS)

    Henle, K.J.; Nagle, W.A.; Moss, A.J.

    1987-01-01

    Cytoxicity of 1 M ethanol was strongly temperature dependent; survival curves between 34 0 and 39 0 C were similar to heat survival curves between 40 and 45 0 without ethanol. Ethanol was non-toxic at 22 0 ; at 34.5 0 and 35.5 0 ethanol survival curves were biphasic. The major effect of 1 M ethanol was an effective temperature shift of 6.4 Celsius degrees, although temperatures between 34 0 and 36 0 caused additional sensitization reminiscent of the stepdown heating phenomenon. Induction of thermotolerance with equitoxic ethanol exposures at 35.5 0 and 37 0 or with heat alone (10 min, 45 0 ) resulted in tolerance development with similar kinetics; in contrast, ethanol exposures at 22 0 did not induce any tolerance development with similar kinetics; in contrast, ethanol exposures at 22 0 did not induce any tolerance to hyperthermia. These data provide a rationale for conflicting reports in the literature regarding thermotolerance induction by ethanol and suggest that ethanol causes ''heat'' stress at temperatures that are generally considered to be physiological. This interpretation predicts that the use of ethanol and other organic solvents in high concentrations will cause effects at 37 0 that normally occur only at hyperthermic temperatures, including membrane perturbations and HSP synthesis, and that ''physiological'' temperatures must be precisely controlled under those conditions

  18. Temperature dependence of interlayer coupling in perpendicular magnetic tunnel junctions with GdOX barriers

    Science.gov (United States)

    Newhouse-Illige, T.; Xu, Y. H.; Liu, Y. H.; Huang, S.; Kato, H.; Bi, C.; Xu, M.; LeRoy, B. J.; Wang, W. G.

    2018-02-01

    Perpendicular magnetic tunnel junctions with GdOX tunneling barriers have shown a unique voltage controllable interlayer magnetic coupling effect. Here, we investigate the quality of the GdOX barrier and the coupling mechanism in these junctions by examining the temperature dependence of the tunneling magnetoresistance and the interlayer coupling from room temperature down to 11 K. The barrier is shown to be of good quality with the spin independent conductance only contributing a small portion, 14%, to the total room temperature conductance, similar to AlOX and MgO barriers. The interlayer coupling, however, shows an anomalously strong temperature dependence including sign changes below 80 K. This non-trivial temperature dependence is not described by previous models of interlayer coupling and may be due to the large induced magnetic moment of the Gd ions in the barrier.

  19. Temperature dependence of APD-based PET scanners

    International Nuclear Information System (INIS)

    Keereman, Vincent; Van Holen, Roel; Vandenberghe, Stefaan; Vanhove, Christian

    2013-01-01

    Purpose: Solid state detectors such as avalanche photodiodes (APDs) are increasingly being used in PET detectors. One of the disadvantages of APDs is the strong decrease of their gain factor with increasing ambient temperature. The light yield of most scintillation crystals also decreases when ambient temperature is increased. Both effects lead to considerable temperature dependence of the performance of APD-based PET scanners. In this paper, the authors propose a model for this dependence and the performance of the LabPET8 APD-based small animal PET scanner is evaluated at different temperatures.Methods: The model proposes that the effect of increasing temperature on the energy histogram of an APD-based PET scanner is a compression of the histogram along the energy axis. The energy histogram of the LabPET system was acquired at 21 °C and 25 °C to verify the validity of this model. Using the proposed model, the effect of temperature on system sensitivity was simulated for different detector temperature coefficients and temperatures. Subsequently, the effect of short term and long term temperature changes on the peak sensitivity of the LabPET system was measured. The axial sensitivity profile was measured at 21 °C and 24 °C following the NEMA NU 4-2008 standard. System spatial resolution was also evaluated. Furthermore, scatter fraction, count losses and random coincidences were evaluated at different temperatures. Image quality was also investigated.Results: As predicted by the model, the photopeak energy at 25 °C is lower than at 21 °C with a shift of approximately 6% per °C. Simulations showed that this results in an approximately linear decrease of sensitivity when temperature is increased from 21 °C to 24 °C and energy thresholds are constant. Experimental evaluation of the peak sensitivity at different temperatures showed a strong linear correlation for short term (2.32 kcps/MBq/°C = 12%/°C, R = −0.95) and long term (1.92 kcps/MBq/°C = 10%/

  20. Temperature dependence of LRE-HRE-TM thin films

    Science.gov (United States)

    Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

    2003-04-01

    Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

  1. Temperature dependence of the magnetization of canted spin structures

    DEFF Research Database (Denmark)

    Jacobsen, Henrik; Lefmann, Kim; Brok, Erik

    2012-01-01

    Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models for the ......Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models...... for the temperature dependence of the magnetization of a simple canted spin structure in which relaxation can take place at finite temperatures between spin configurations with different canting angles. We show that the saturation magnetization may either decrease or increase with decreasing temperature, depending...

  2. Temperature dependence of work hardening in sparsely twinning zirconium

    International Nuclear Information System (INIS)

    Singh, Jaiveer; Mahesh, S.; Roy, Shomic; Kumar, Gulshan; Srivastava, D.; Dey, G.K.; Saibaba, N.; Samajdar, I.

    2017-01-01

    Fully recrystallized commercial Zirconium plates were subjected to uniaxial tension. Tests were conducted at different temperatures (123 K - 623 K) and along two plate directions. Both directions were nominally unfavorable for deformation twinning. The effect of the working temperature on crystallographic texture and in-grain misorientation development was insignificant. However, systematic variation in work hardening and in the area fraction and morphology of deformation twins was observed with temperature. At all temperatures, twinning was associated with significant near boundary mesoscopic shear, suggesting a possible linkage with twin nucleation. A binary tree based model of the polycrystal, which explicitly accounts for grain boundary accommodation and implements the phenomenological extended Voce hardening law, was implemented. This model could capture the measured stress-strain response and twin volume fractions accurately. Interestingly, slip and twin system hardness evolution permitted multiplicative decomposition into temperature-dependent, and accumulated strain-dependent parts. Furthermore, under conditions of relatively limited deformation twinning, the work hardening of the slip and twin systems followed two phenomenological laws proposed in the literature for non-twinning single-phase face centered cubic materials.

  3. Temperature dependence of sound velocity in yttrium ferrite

    International Nuclear Information System (INIS)

    L'vov, V.A.

    1979-01-01

    The effect of the phonon-magnon and phonon-phonon interoctions on the temperature dependence of the longitudinal sound velocity in yttrium ferrite is considered. It has been shown that at low temperatures four-particle phonon-magnon processes produce the basic contribution to renormalization of the sound velocity. At higher temperatures the temperature dependence of the sound velocity is mainly defined by phonon-phonon processes

  4. Identification of temperature-dependent thermal conductivity and experimental verification

    International Nuclear Information System (INIS)

    Pan, Weizhen; Yi, Fajun; Zhu, Yanwei; Meng, Songhe

    2016-01-01

    A modified Levenberg–Marquardt method (LMM) for the identification of temperature-dependent thermal conductivity is proposed; the experiment and structure of the specimen for identification are also designed. The temperature-dependent thermal conductivities of copper C10200 and brass C28000 are identified to verify the effectiveness of the proposed identification method. The comparison between identified results and the measured data of laser flash diffusivity apparatus indicates the fine consistency and potential usage of the proposed method. (paper)

  5. A Simple Method to Calculate the Temperature Dependence of the Gibbs Energy and Chemical Equilibrium Constants

    Science.gov (United States)

    Vargas, Francisco M.

    2014-01-01

    The temperature dependence of the Gibbs energy and important quantities such as Henry's law constants, activity coefficients, and chemical equilibrium constants is usually calculated by using the Gibbs-Helmholtz equation. Although, this is a well-known approach and traditionally covered as part of any physical chemistry course, the required…

  6. Temperature dependence of mobility in silicon (100) inversion layers at low temperatures

    International Nuclear Information System (INIS)

    Kawaguchi, Y.; Suzuki, T.; Kawaji, S.

    1982-01-01

    Electron mobility of Si(100) n-inversion layers in MOSFETs having μsub(peak) (4.2 K) = 4000.6500 and 12000 cm 2 /V x s has been measured at temperatures between 1 and 80 K. The carrier concentration dependence of the mobility extrapolated to T = O and the temperature dependent part of the scattering probability are investigated. (orig.)

  7. Temperature dependence of the extraordinary Hall effect in magnetic granular alloys

    International Nuclear Information System (INIS)

    Granovsky, A.; Kalitsov, A.; Khanikaev, A.; Sato, H.; Aoki, Y.

    2003-01-01

    We present the results of theoretical investigation of the temperature dependence of the extraordinary Hall effect (EHE) in granular metal-metal and metal-insulator alloys in the case of electron-phonon scattering at high temperatures. Skew scattering is assumed to be the dominant mechanism of the EHE. The calculations were carried out using Zhang-Levy model and the effective-medium approximation. The single-site electron-phonon interaction model was considered by analogy to that one in the theory of disordered alloys. In the case of strong spin-dependent scattering there is an additional term in the temperature dependence of the EHE coefficient of magnetic granular alloys in comparison with that for bulk ferromagnets. This term is linear with T 3 . The similar temperature dependence for the EHE conductivity in granular metal-metal and metal-insulator alloys takes place in spite of the different origin of giant magnetoresistance in these systems. The strong temperature dependence of the EHE coefficient can be viewed as an evidence of enhanced spin-orbit interaction at interfaces between granules and the matrix. We show a linear correlation between the interface contribution to the EHE coefficient and the interface contribution to alloy resistivity. The obtained results are in a qualitative agreement with the recent experimental data for nanocomposites

  8. Temperature dependence of the extraordinary Hall effect in magnetic granular alloys

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, A. E-mail: granov@magn.ru; Kalitsov, A.; Khanikaev, A.; Sato, H.; Aoki, Y

    2003-02-01

    We present the results of theoretical investigation of the temperature dependence of the extraordinary Hall effect (EHE) in granular metal-metal and metal-insulator alloys in the case of electron-phonon scattering at high temperatures. Skew scattering is assumed to be the dominant mechanism of the EHE. The calculations were carried out using Zhang-Levy model and the effective-medium approximation. The single-site electron-phonon interaction model was considered by analogy to that one in the theory of disordered alloys. In the case of strong spin-dependent scattering there is an additional term in the temperature dependence of the EHE coefficient of magnetic granular alloys in comparison with that for bulk ferromagnets. This term is linear with T{sup 3}. The similar temperature dependence for the EHE conductivity in granular metal-metal and metal-insulator alloys takes place in spite of the different origin of giant magnetoresistance in these systems. The strong temperature dependence of the EHE coefficient can be viewed as an evidence of enhanced spin-orbit interaction at interfaces between granules and the matrix. We show a linear correlation between the interface contribution to the EHE coefficient and the interface contribution to alloy resistivity. The obtained results are in a qualitative agreement with the recent experimental data for nanocomposites.

  9. Temperature dependence of three-body ion-molecule reactions

    International Nuclear Information System (INIS)

    Boehringer, H.; Arnold, F.

    1983-01-01

    The temperature dependence of the ion-molecule association reactions (i) N 2 + + N 2 + M → N 4 + + M (M=N 2 , He), (ii) O 2 + + O 2 + M → O 4 + + M (M=O 2 , He) and (iii) He + + 2He → He 2 + + He have been studied over an extended temperature range to temperatures as low as 30K with a recently constructed liquid helium-cooled ion drift tube. Over most of the temperature range the threebody reaction rate coefficients show an inverse temperature dependence proportional to Tsup(-n) with n in the range 0.6 to 2.9. This temperature dependence is quite consistent with current theories of ion molecule association. At low temperatures, however, a deviation from the Tsup(-n) dependence was observed for the association reactions (ii). For reactions (i) different temperature dependences were obtained for N 2 and He third bodies indicating an additional temperature dependence of the collisional stabilisation process. (Authors)

  10. Effect of temperature dependent properties on MHD convection of water near its density maximum in a square cavity

    International Nuclear Information System (INIS)

    Sivasankaran, S.; Hoa, C.J.

    2008-01-01

    Natural convection of water near its density maximum in the presence of magnetic field in a cavity with temperature dependent properties is studied numerically. The viscosity and thermal conductivity of the water is varied with reference temperature and calculated by cubic polynomial. The finite volume method is used to solve the governing equations. The results are presented graphically in the form of streamlines, isotherms and velocity vectors and are discussed for various combinations of reference temperature parameter, Rayleigh number, density inversion parameter and Hartmann number. It is observed that flow and temperature field are affected significantly by changing the reference temperature parameter for temperature dependent thermal conductivity and both temperature dependent viscosity and thermal conductivity cases. There is no significant effect on fluid flow and temperature distributions for temperature dependent viscosity case when changing the values of reference temperature parameter. The average heat transfer rate considering temperature-dependent viscosity are higher than considering temperature-dependent thermal conductivity and both temperature-dependent viscosity and thermal conductivity. The average Nusselt number decreases with an increase of Hartmann number. It is observed that the density inversion of water leaves strong effects on fluid flow and heat transfer due to the formation of bi-cellular structure. The heat transfer rate behaves non-linearly with density inversion parameter. The direction of external magnetic field also affect the fluid flow and heat transfer. (authors)

  11. Energy based model for temperature dependent behavior of ferromagnetic materials

    International Nuclear Information System (INIS)

    Sah, Sanjay; Atulasimha, Jayasimha

    2017-01-01

    An energy based model for temperature dependent anhysteretic magnetization curves of ferromagnetic materials is proposed and benchmarked against experimental data. This is based on the calculation of macroscopic magnetic properties by performing an energy weighted average over all possible orientations of the magnetization vector. Most prior approaches that employ this method are unable to independently account for the effect of both inhomogeneity and temperature in performing the averaging necessary to model experimental data. Here we propose a way to account for both effects simultaneously and benchmark the model against experimental data from ~5 K to ~300 K for two different materials in both annealed (fewer inhomogeneities) and deformed (more inhomogeneities) samples. This demonstrates that this framework is well suited to simulate temperature dependent experimental magnetic behavior. - Highlights: • Energy based model for temperature dependent ferromagnetic behavior. • Simultaneously accounts for effect of temperature and inhomogeneities. • Benchmarked against experimental data from 5 K to 300 K.

  12. Temperature dependent charge transport in poly(3-hexylthiophene) diodes

    Science.gov (United States)

    Rahaman, Abdulla Bin; Sarkar, Atri; Banerjee, Debamalya

    2018-04-01

    In this work, we present charge transport properties of poly(3-hexylthiophene) (P3HT) diodes under dark conditions. Temperature dependent current-voltage (J-V) characteristics shows that charge transport represents a transition from ohomic to trap limited current. The forward current density obeys a power law J˜Vm, m>2 represents the space charge limited current region in presence of traps within the band gap. Frequency dependent conductivity has been studied in a temperature range 150K-473K. The dc conductivity values show Arrhenius like behavior and it gives conductivity activation energy 223 meV. Temperature dependent conductivity indicates a thermodynamic transition of our system.

  13. Study of Cu-Al-Zn alloys hardness temperature dependence

    International Nuclear Information System (INIS)

    Kurmanova, D.T.; Skakov, M.K.; Melikhov, V.D.

    2001-01-01

    In the paper the results of studies for the Cu-Al-Zn ternary alloys hardness temperature dependence are presented. The method of 'hot hardness' has been used during study of the solid state phase transformations and under determination of the hot stability boundaries. Due to the samples brittleness a hardness temperature dependence definition is possible only from 350-400 deg. C. Sensitivity of the 'hot hardness' method is decreasing within high plasticity range, so the measurements have been carried out only up to 700-800 deg. C. It is shown, that the alloys hardness dependence character from temperature is close to exponential one within the certain structure modification existence domain

  14. Temperature dependence of fluorescence decay time and emission spectrum of bismuth germanate

    International Nuclear Information System (INIS)

    Melcher, C.L.; Liberman, A.; Schweitzer, J.S.; Simonetti, J.

    1985-01-01

    Bismuth germanate has become an increasingly popular replacement for NaI(Tl) scintillators in recent years, mainly due to its higher detection efficiency. However, its scintillation efficiency and fluorescence decay time are strongly temperature dependent. Optimum performance of detector systems which employ BGO crystals depends on knowledge of the BGO pulse shape and intensity and its emission spectrum at the operating temperature of the detector. Measurements of these quantities are presented over the temperature range -47 0 C to +111 0 C. Although the emission spectrum shifts only slightly over this temperature range, the scintillation efficiency and fluorescence decay time are strongly temperature dependent. In addition to the usefulness of these data for optimizing detector design, the results imply that luminescence quenching in BGO cannot be characterized by a single thermal activation to a radiationless transition but that a more complex model is required to characterize the light output from BGO crystals

  15. Temperature dependence of shot noise in double barrier magnetic tunnel junctions

    Science.gov (United States)

    Niu, Jiasen; Liu, Liang; Feng, J. F.; Han, X. F.; Coey, J. M. D.; Zhang, X.-G.; Wei, Jian

    2018-03-01

    Shot noise reveals spin dependent transport properties in a magnetic tunnel junction. We report measurement of shot noise in CoFeB/MgO/CoFeB/MgO/CoFeB double barrier magnetic tunnel junctions, which shows a strong temperature dependence. The Fano factor used to characterize shot noise increases with decreasing temperature. A sequential tunneling model can be used to account for these results, in which a larger Fano factor results from larger spin relaxation length at lower temperatures.

  16. Voltage and temperature dependence of the grain boundary tunneling magnetoresistance in manganites

    OpenAIRE

    Hoefener, C.; Philipp, J. B.; Klein, J.; Alff, L.; Marx, A.; Buechner, B.; Gross, R.

    2000-01-01

    We have performed a systematic analysis of the voltage and temperature dependence of the tunneling magnetoresistance (TMR) of grain boundaries (GB) in the manganites. We find a strong decrease of the TMR with increasing voltage and temperature. The decrease of the TMR with increasing voltage scales with an increase of the inelastic tunneling current due to multi-step inelastic tunneling via localized defect states in the tunneling barrier. This behavior can be described within a three-current...

  17. Temperature dependence of nitrogen solubility in iron base multicomponent melts

    International Nuclear Information System (INIS)

    Sokolov, V.M.; Koval'chuk, L.A.

    1986-01-01

    Method for calculating temperature dependence of nitrogen solubility in iron base multicomponent melts is suggested. Application areas of existing methods were determined and advantages of the new method for calculating nitrogen solubility in multicomponent-doped iron melts (Fe-Ni-Cr-Mo, Fe-Ni-Cr-Mn, Fe-Mo-V) at 1773-2073 K are shown

  18. Arrhenius temperature dependence of in vitro tissue plasminogen activator thrombolysis

    International Nuclear Information System (INIS)

    Shaw, George J; Dhamija, Ashima; Bavani, Nazli; Wagner, Kenneth R; Holland, Christy K

    2007-01-01

    Stroke is a devastating disease and a leading cause of death and disability. Currently, the only FDA approved therapy for acute ischemic stroke is the intravenous administration of the thrombolytic medication, recombinant tissue plasminogen activator (tPA). However, this treatment has many contraindications and can have dangerous side effects such as intra-cerebral hemorrhage. These treatment limitations have led to much interest in potential adjunctive therapies, such as therapeutic hypothermia (T ≤ 35 deg. C) and ultrasound enhanced thrombolysis. Such interest may lead to combining these therapies with tPA to treat stroke, however little is known about the effects of temperature on the thrombolytic efficacy of tPA. In this work, we measure the temperature dependence of the fractional clot mass loss Δm(T) resulting from tPA exposure in an in vitro human clot model. We find that the temperature dependence is well described by an Arrhenius temperature dependence with an effective activation energy E eff of 42.0 ± 0.9 kJ mole -1 . E eff approximates the activation energy of the plasminogen-to-plasmin reaction of 48.9 kJ mole -1 . A model to explain this temperature dependence is proposed. These results will be useful in predicting the effects of temperature in future lytic therapies

  19. Quasi-pions with temperature dependent dispersion relation

    International Nuclear Information System (INIS)

    Gorenstein, M.I.

    1995-01-01

    We construct the procedure to calculate thermodynamical functions for a system of quasi-particles with temperature dependent dispersion relation. Two models for the hot quasi-pion system are considered to illustrate the importance of thermodynamical self consistency requirements. 8 refs., 9 figs

  20. Temperature dependence of the μ+ hyperfine field in ferromagnets

    International Nuclear Information System (INIS)

    Nagamine, K.; Nirhida, N.; Hayano, R.S.; Yamazaki, T.; Brewes, J.H.; Fleming, D.G.

    1977-01-01

    The temperature dependences of the μ + hyperfine fields in Ni and in Fe were found to deviate from that of the saturation magnetization in opposite senses. Difference in the screening mechanism of conduction electrons around the μ + is considered, among several possible explanations. (Auth.)

  1. Arrhenius temperature dependence of in vitro tissue plasminogen activator thrombolysis

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, George J [Department of Emergency Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0769 (United States); Dhamija, Ashima [Department of Emergency Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0769 (United States); Bavani, Nazli [Department of Emergency Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0769 (United States); Wagner, Kenneth R [Department of Neurology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0769 (United States); Holland, Christy K [Department of Biomedical Engineering, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0769 (United States)

    2007-06-07

    Stroke is a devastating disease and a leading cause of death and disability. Currently, the only FDA approved therapy for acute ischemic stroke is the intravenous administration of the thrombolytic medication, recombinant tissue plasminogen activator (tPA). However, this treatment has many contraindications and can have dangerous side effects such as intra-cerebral hemorrhage. These treatment limitations have led to much interest in potential adjunctive therapies, such as therapeutic hypothermia (T {<=} 35 deg. C) and ultrasound enhanced thrombolysis. Such interest may lead to combining these therapies with tPA to treat stroke, however little is known about the effects of temperature on the thrombolytic efficacy of tPA. In this work, we measure the temperature dependence of the fractional clot mass loss {delta}m(T) resulting from tPA exposure in an in vitro human clot model. We find that the temperature dependence is well described by an Arrhenius temperature dependence with an effective activation energy E{sub eff} of 42.0 {+-} 0.9 kJ mole{sup -1}. E{sub eff} approximates the activation energy of the plasminogen-to-plasmin reaction of 48.9 kJ mole{sup -1}. A model to explain this temperature dependence is proposed. These results will be useful in predicting the effects of temperature in future lytic therapies.

  2. Hysteresis and Temperature Dependency of Moisture Sorption – New Measurements

    DEFF Research Database (Denmark)

    Rode, Carsten; Hansen, Kurt Kielsgaard

    2011-01-01

    measurements of hysteresis and temperature dependency of the moisture sorption characteristics of three different porous building materials: aerated concrete, cement paste and spruce. Scanning curves are measured for all three materials where periods with adsorption and desorption interrupt each other...... intermittently. For one of the materials, aerated concrete, the sorption curves are determined at three different temperatures....

  3. Temperature dependence of the resonance frequency of thermogravimetric devices

    NARCIS (Netherlands)

    Iervolino, E.; Riccio, M.; Van Herwaarden, A.W.; Irace, A.; Breglio, G.; Van der Vlist, W.; Sarro, P.M.

    2010-01-01

    This paper investigates the temperature dependence of the resonance frequency of thermogravimetric (TG) devices for tip heating over the temperature range of View the MathML source 25–600?C. The resonance frequency of a fabricated TG device shows to be temperature independent for tip heating up to

  4. Temperature Dependence of Lattice Dynamics of Lithium 7

    DEFF Research Database (Denmark)

    Beg, M. M.; Nielsen, Mourits

    1976-01-01

    10% smaller than those at 100 K. Temperature dependences of selected phonons have been studied from 110 K to near the melting point. The energy shifts and phonon linewidths have been evaluated at 293, 383, and 424 K by comparing the widths and energies to those measured at 110 K. The lattice...

  5. Anomalous temperature dependence of excitation transfer between quantum dots

    Czech Academy of Sciences Publication Activity Database

    Král, Karel; Menšík, Miroslav

    2015-01-01

    Roč. 7, č. 4 (2015), 325-330 ISSN 2164-6627 R&D Projects: GA MŠk(CZ) LD14011; GA MŠk LH12236; GA MŠk LH12186 Institutional support: RVO:68378271 ; RVO:61389013 Keywords : excitation transfer * quantum dots * temperature dependence * electron-phonon interaction Subject RIV: BM - Solid Matter Physics ; Magnetism

  6. Temperature dependence of critical resolved shear stress for cubic metals

    International Nuclear Information System (INIS)

    Rashid, H.; Fazal-e-Aleem; Ali, M.

    1996-01-01

    The experimental measurements for critical resolved shear stress of various BCC and FCC metals have been explained by using Radiation Model. The temperature dependence of CRSS for different cubic metals is found to the first approximation, to upon the type of the crystal. A good agreement between experimental observations and predictions of the Radiation Model is found. (author)

  7. Temperature dependence of collapse of quantized hall resistance

    International Nuclear Information System (INIS)

    Tanaka, Hiroyasu; Kawashima, Hironori; Iizuka, Hisamitsu; Fukuda, Hideaki; Kawaji, Shinji

    2006-01-01

    Similarity is observed in the deviation of Hall resistance from the quantized value with the increase in the source-drain current I SD in our butterfly-type Hall bars and in the Hall bars used by Jeanneret et al., while changes in the diagonal resistivity ρ xx with I SD are significantly different between these Hall bars. The temperature dependence of the critical Hall electric field F cr (T) for the collapse of R H (4) measured in these Hall bars is approximated using F cr (T) = F cr (0)(1 - (T/T cr ) 2 ). Here, the critical Hall electric field at zero temperature depends on the magnetic field B as F cr (0) ∝ B 3/2 . Theoretical considerations are given on F cr (T) on the basis of a temperature-dependent mobility edge model and a schema of temperature-dependent inter-Landau level tunneling probability arising from the Fermi distribution function. The former does not fit in with the I SD dependence of activation energy in ρ xx . (author)

  8. Temperature dependence of electron concentration in cadmium arsenide

    NARCIS (Netherlands)

    Gelten, M.J.; Blom, F.A.P.

    1979-01-01

    From measurements of the temperature dependence of the electron concentration in Cd 3 As 2 , we found values for the conduction-band parameters that are in good agreement with those recently reported by Aubin, Caron, and Jay-Gerin. However, in contrast with these authors we found no small overlap,

  9. Crossing regimes of temperature dependence in animal movement.

    Science.gov (United States)

    Gibert, Jean P; Chelini, Marie-Claire; Rosenthal, Malcolm F; DeLong, John P

    2016-05-01

    A pressing challenge in ecology is to understand the effects of changing global temperatures on food web structure and dynamics. The stability of these complex ecological networks largely depends on how predator-prey interactions may respond to temperature changes. Because predators and prey rely on their velocities to catch food or avoid being eaten, understanding how temperatures may affect animal movement is central to this quest. Despite our efforts, we still lack a mechanistic understanding of how the effect of temperature on metabolic processes scales up to animal movement and beyond. Here, we merge a biomechanical approach, the Metabolic Theory of Ecology and empirical data to show that animal movement displays multiple regimes of temperature dependence. We also show that crossing these regimes has important consequences for population dynamics and stability, which depend on the parameters controlling predator-prey interactions. We argue that this dependence upon interaction parameters may help explain why experimental work on the temperature dependence of interaction strengths has so far yielded conflicting results. More importantly, these changes in the temperature dependence of animal movement can have consequences that go well beyond ecological interactions and affect, for example, animal communication, mating, sensory detection, and any behavioral modality dependent on the movement of limbs. Finally, by not taking into account the changes in temperature dependence reported here we might not be able to properly forecast the impact of global warming on ecological processes and propose appropriate mitigation action when needed. © 2016 John Wiley & Sons Ltd.

  10. Temperature dependence of dose rate laser simulation adequacy

    International Nuclear Information System (INIS)

    Skorobogatov, P.K.; Nikiforov, A.Y.; Demidov, A.A.

    1999-01-01

    2-D numerical modeling was carried out to analyze the temperature dependence of dose rate laser simulation adequacy in application to p-n junction ionising current. Experimental validation was performed using test structure in the temperature range of 0 to 100 deg.C. (authors)

  11. Temperature Dependence Viscosity and Density of Different Biodiesel Blends

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2015-01-01

    Full Text Available The main goal of this paper is to assess the effect of rapeseed oil methyl ester (RME concentration in diesel fuel on its viscosity and density behaviour. The density and dynamic viscosity were observed at various mixing ratios of RME and diesel fuel. All measurements were performed at constant temperature of 40 °C. Increasing ratio of RME in diesel fuel was reflected in increased density value and dynamic viscosity of the blend. In case of pure RME, pure diesel fuel, and a blend of both (B30, temperature dependence of dynamic viscosity and density was examined. Temperature range in the experiment was −10 °C to 80 °C. Considerable temperature dependence of dynamic viscosity and density was found and demonstrated for all three samples. This finding is in accordance with theoretical assumptions and reference data. Mathematical models were developed and tested. Temperature dependence of dynamic viscosity was modeled using a polynomial 3rd polynomial degree. Correlation coefficients R −0.796, −0.948, and −0.974 between measured and calculated values were found. Temperature dependence of density was modeled using a 2nd polynomial degree. Correlation coefficients R −0.994, −0.979, and −0.976 between measured and calculated values were acquired. The proposed models can be used for flow behaviour prediction of RME, diesel fuel, and their blends.

  12. Strong winds in South Africa, part 2: mapping of updated statistics

    CSIR Research Space (South Africa)

    Kruger, AC

    2013-08-01

    Full Text Available winds in South Africa imperative. Based on the estimation of strong winds as reported in the accompanying paper (see page 29 in this volume), the spatial interpolation of 50-year characteristic strong wind values to provide updated design wind speed maps...

  13. Frequency and temperature dependent mobility of a charged carrier and randomly interrupted strand

    International Nuclear Information System (INIS)

    Kumar, N.; Jayannavar, A.M.

    1981-05-01

    Randomly interrupted strand model of a one-dimensional conductor is considered. Exact analytical expression is obtained for the temperature dependent as mobility for a finite segment drawn at random, taking into account the reflecting barriers at the two open ends. The real part of mobility shows a broad resonance as a function of both frequency and tempeature, and vanishes quadratically in the dc limit. The frequency (temperature) maximum shifts to higher values for higher temperatures (frequencies). (author)

  14. The role of inelastic processes in the temperature dependence of hall induced resistance oscillations

    International Nuclear Information System (INIS)

    Kunold, Alejandro; Torres, Manuel

    2013-01-01

    We develop a model of magnetoresistance oscillations induced by the Hall field in order to study the temperature dependence observed in recent experiments in two dimensional electron systems. The model is based on the solution of the von Neumann equation incorporating the exact dynamics of two-dimensional damped electrons in the presence of arbitrarily strong magnetic and dc electric fields, while the effects of randomly distributed neutral and charged impurities are perturbatively added. Both the effects of elastic impurity scattering as well as those related to inelastic processes play an important role. The theoretical predictions correctly reproduce the experimentally observed oscillations amplitude, provided that the quantum inelastic scattering rate obeys a T 2 temperature dependence, consistent with electron–electron interaction effects

  15. Temperature-dependent structural relaxation in As{sub 40}Se{sub 60} glass

    Energy Technology Data Exchange (ETDEWEB)

    Golovchak, R., E-mail: roman_ya@yahoo.com [Lviv Sci. and Res. Institute of Materials of SRC ' Carat' , 202 Stryjska str., 79031 Lviv (Ukraine); Kozdras, A. [Opole University of Technology, 75, Ozimska str., Opole, PL-45370 (Poland); Academy of Management and Administration, 18 Niedzialkowski str., Opole, PL-45085 (Poland); Shpotyuk, O. [Jan Dlugosz University, 13/15, al. Armii Krajowej, 42201, Czestochowa (Poland); Gorecki, Cz. [Opole University of Technology, 75, Ozimska str., Opole, PL-45370 (Poland); Kovalskiy, A.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States)

    2011-08-01

    The origin of structural relaxation in As{sub 40}Se{sub 60} glass at different annealing temperatures is studied by differential scanning calorimetry (DSC) and in situ extended X-ray absorption fine structure (EXAFS) methods. Strong physical aging effect, expressed through the increase of endothermic peak area in the vicinity of T{sub g}, is recorded by DSC technique at the annealing temperatures T{sub a}>90{sup o}C. EXAFS data show that the observed structural relaxation is not associated with significant changes in the short-range order of this glass. An explanation is proposed for this relaxation behavior assuming temperature-dependent constraints. -- Highlights: → In this study we report experimental evidence for temperature-dependent constraints theory. → Structural relaxation of As{sub 2}Se{sub 3} glass at higher annealing temperatures is studied by DSC technique. → Accompanied changes in the structure are monitored by in situ EXAFS measurements.

  16. Interrelated temperature dependence of bulk etch rate and track length saturation time in CR-39 detector

    International Nuclear Information System (INIS)

    Azooz, A.A.; Al-Jubbori, M.A.

    2013-01-01

    Highlights: • New empirical parameterization of CR-39 bulk etch rate. • Bulk etch rates measurements using two different methods give consistent results. • Temperature independence of track saturation length. • Two empirical relation between bulk etch rate and temperature are suggested. • Simple inverse relation between bulk etch rate and track saturation time. -- Abstract: Experimental measurements of the etching solution temperature dependence of bulk etch rate using two independent methods revealed a few interesting properties. It is found that while the track saturation length is independent of etching temperature, the etching time needed to reach saturation is strongly temperature-dependent. It is demonstrated that there is systematic simple inverse relation between track saturation time, and etching solution temperature. In addition, and although, the relation between the bulk etch rate and etching solution temperature can be reasonably described by a modified form of the Arrhenius equation, better fits can be obtained by another equation suggested in this work

  17. Temperature dependent thermoelectric properties of chemically derived gallium zinc oxide thin films

    KAUST Repository

    Barasheed, Abeer Z.; Sarath Kumar, S. R.; Alshareef, Husam N.

    2013-01-01

    In this study, the temperature dependent thermoelectric properties of sol-gel prepared ZnO and 3% Ga-doped ZnO (GZO) thin films have been explored. The power factor of GZO films, as compared to ZnO, is improved by nearly 17% at high temperature. A stabilization anneal, prior to thermoelectric measurements, in a strongly reducing Ar/H2 (95/5) atmosphere at 500°C was found to effectively stabilize the chemically derived films, practically eliminating hysteresis during thermoelectric measurements. Subtle changes in the thermoelectric properties of stabilized films have been correlated to oxygen vacancies and excitonic levels that are known to exist in ZnO-based thin films. The role of Ga dopants and defects, formed upon annealing, in driving the observed complex temperature dependence of the thermoelectric properties is discussed. © The Royal Society of Chemistry 2013.

  18. Temperature dependence of the upper critical field of type II superconductors with fluctuation effects

    International Nuclear Information System (INIS)

    Mikitik, G.P.

    1992-01-01

    Fluctuations of the order parameter are taken into consideration in an analysis of the temperature dependence of the upper critical field of a type II superconductor with a three-dimensional superconductivity. This temperature dependence is of universal applicability, to all type II superconductors, if the magnetic fields and temperatures are expressed in appropriate units. This dependence is derived explicitly for the regions of strong and weak magnetic fields. The results are applied to high T c superconductors, for which fluctuation effects are important. For these superconductors, the H c2 (T) dependence is quite different from the linear dependence characteristic of the mean-field theory, over a broad range of magnetic fields

  19. On the Temperature Dependence of the UNIQUAC/UNIFAC Models

    DEFF Research Database (Denmark)

    Skjold-Jørgensen, Steen; Rasmussen, Peter; Fredenslund, Aage

    1980-01-01

    of the simultaneous correlation. The temperature dependent parameters have, however, little physical meaning and very odd results are frequently obtained when the interaction parameters obtained from excess enthalpy information alone are used for the prediction of vapor-liquid equilibria. The UNIQUAC/UNIFAC models...... parameters based on excess enthalpy data, and the prediction of excess enthalpy information from only one isothermal set of vapor-liquid equilibrium data is qualitatively acceptable. A parameter table for the modified UNIFAC model is given for the five main groups: CH2, C = C, ACH, ACCH2 and CH2O.......Local composition models for the description of the properties of liquid mixtures do not in general give an accurate representation of excess Gibbs energy and excess enthalpy simultaneously. The introduction of temperature dependent interaction parameters leads to considerable improvements...

  20. Temperature dependence of high field electromechanical coupling in ferroelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P M; Cain, M G; Stewart, M, E-mail: paul.weaver@npl.co.u [National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW (United Kingdom)

    2010-04-28

    A study of the temperature dependence of the electromechanical response of ferroelectric lead zirconate titanate (PZT) ceramics at high electric fields (up to 1.3 kV mm{sup -1}) is reported. Simultaneous measurements were performed of strain, electric field and polarization to form a complete response map from room temperature up to 200 {sup 0}C. An electrostrictive model is shown to provide an accurate description of the electromechanical response to high levels of induced polarization and electric field. This provides a method for decoupling strain contributions from thermal expansion and polarization changes. Direct measurements of electrostriction and thermal expansion, above and below the Curie temperature, are reported. Electrostriction coefficients are shown to be temperature dependent in these ceramic materials, with different values above and below the Curie temperature.

  1. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    Science.gov (United States)

    Nicovich, J. M.; Wine, P. H.

    1988-01-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  2. Temperature dependence of magnetoresistance in lanthanum manganite ceramics

    International Nuclear Information System (INIS)

    Gubkin, M.K.; Zalesskii, A.V.; Perekalina, T.M.

    1996-01-01

    Magnetoresistivity in the La0.9Na0.1Mn0.9(V,Co)0.1O3 and LaMnO3+δ ceramics was studied. The temperature dependence of magnetoresistance in these specimens was found to differ qualitatively from that in the La0.9Na0.1MnO3 single crystal (the magnetoresistance value remains rather high throughout the measurement range below the Curie temperature), with the maximum values being about the same (20-40% in the field of 20 kOe). Previously published data on magnetization, high frequency magnetic susceptibility, and local fields at the 139La nuclei of the specimens with similar properties attest to their magnetic inhomogeneity. The computation of the conductivity of the nonuniformly ordered lanthanum manganite was performed according to the mean field theory. The calculation results allow one to interpret qualitatively various types of experimental temperature dependences of magnetoresistance

  3. Temperature-dependent enthalpy of oxygenation in Antarctic fish hemoglobins

    DEFF Research Database (Denmark)

    Fago, A.; Wells, R.M.G.; Weber, Roy E.

    1997-01-01

    The effect of temperature on the oxygen-binding properties of the hemoglobins of three cold-adapted Antarctic fish species, Dissostichus mawsoni, Pagothenia borchgrevinki and Trematomus, sp., has been investigated under different pH values and buffer conditions. A clear non linear van't Hoff plot...... (logP(50) vs 1/T) of D. mawsoni hemoglobin indicates that the enthalpy of oxygenation (slope of the plot) is temperature dependent and that at high temperatures oxygen-binding becomes less exothermic. Nearly linear relationships were found in the hemoglobins of the other two species. The data were...... oxygen binding. The degree of the temperature dependence of the heat of oxygenation observed in these hemoglobins seems to reflect the differences in their allosteric effects rather than a specific molecular adaptation to low temperatures. Moreover, this study indicates that the disagreement between...

  4. Temperature dependence on the time and momentum spectra in germanium

    International Nuclear Information System (INIS)

    Schultz, P.J.; MacKenzie, I.K.

    1982-01-01

    Recent measurements using the slow-#betta# + beam at Brookhaven, have suggested a thermally activated trapping mechanism which inhibited positron diffusion in single-crystal Ge. Supporting evidence has now been obtained from both Doppler broadening and lifetime measurements but, in both cases, the temperature dependence was so weak that it required the use of dual digital stabilization and unusual statistical precision in both types of spectrometry. (Auth.)

  5. Temperature dependence of spreading width of giant dipole resonance

    International Nuclear Information System (INIS)

    Storozhenko, A.N.; Vdovin, A.I.; Ventura, A.; Blokhin, A.I.

    2002-01-01

    The Quasiparticle-Phonon Nuclear Model extended to finite temperature within the framework of Thermo Field Dynamics is applied to calculate a temperature dependence of the spreading width Γ ↓ of a giant dipole resonance. Numerical calculations are made for 120 Sn and 208 Pb nuclei. It is found that Γ ↓ increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones, existing in the literature

  6. Strong winds in South Africa, part 1: application of estimation methods

    CSIR Research Space (South Africa)

    Kruger, A

    2013-08-01

    Full Text Available into the category for a storm or gale, and is consistent with wind strengths to be expected during a very strong cold front. With regard to the above, Brabson & Palutikof (2000) illustrated the effect of the addition of four very large annual maxima, when... of strong winds experienced at the location where the wind measurements were taken. Using the Method of Independent Storms (MIS) a decision has to be taken on the threshold value which separates individual storms. This value should be high enough...

  7. A nanoscale temperature-dependent heterogeneous nucleation theory

    International Nuclear Information System (INIS)

    Cao, Y. Y.; Yang, G. W.

    2015-01-01

    Classical nucleation theory relies on the hypothetical equilibrium of the whole nucleation system, and neglects the thermal fluctuations of the surface; this is because the high entropic gains of the (thermodynamically extensive) surface would lead to multiple stable states. In fact, at the nanometer scale, the entropic gains of the surface are high enough to destroy the stability of the thermal equilibrium during nucleation, comparing with the whole system. We developed a temperature-dependent nucleation theory to elucidate the heterogeneous nucleation process, by considering the thermal fluctuations based on classical nucleation theory. It was found that the temperature not only affected the phase transformation, but also influenced the surface energy of the nuclei. With changes in the Gibbs free energy barrier, nucleation behaviors, such as the nucleation rate and the critical radius of the nuclei, showed temperature-dependent characteristics that were different from those predicted by classical nucleation theory. The temperature-dependent surface energy density of a nucleus was deduced based on our theoretical model. The agreement between the theoretical and experimental results suggested that the developed nucleation theory has the potential to contribute to the understanding and design of heterogeneous nucleation at the nanoscale

  8. On the temperature dependence of flammability limits of gases.

    Science.gov (United States)

    Kondo, Shigeo; Takizawa, Kenji; Takahashi, Akifumi; Tokuhashi, Kazuaki

    2011-03-15

    Flammability limits of several combustible gases were measured at temperatures from 5 to 100 °C in a 12-l spherical flask basically following ASHRAE method. The measurements were done for methane, propane, isobutane, ethylene, propylene, dimethyl ether, methyl formate, 1,1-difluoroethane, ammonia, and carbon monoxide. As the temperature rises, the lower flammability limits are gradually shifted down and the upper limits are shifted up. Both the limits shift almost linearly to temperature within the range examined. The linear temperature dependence of the lower flammability limits is explained well using a limiting flame temperature concept at the lower concentration limit (LFL)--'White's rule'. The geometric mean of the flammability limits has been found to be relatively constant for many compounds over the temperature range studied (5-100 °C). Based on this fact, the temperature dependence of the upper flammability limit (UFL) can be predicted reasonably using the temperature coefficient calculated for the LFL. However, some compounds such as ethylene and dimethyl ether, in particular, have a more complex temperature dependence. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Temperature dependence of photonic crystals based on thermoresponsive magnetic fluids

    International Nuclear Information System (INIS)

    Pu Shengli; Bai Xuekun; Wang Lunwei

    2011-01-01

    The influence mechanisms of temperature on the band gap properties of the magnetic fluids based photonic crystals are elaborated. A method has been developed to obtain the temperature-dependent structure information (A sol /A) from the existing experimental data and then two critical parameters, i.e. the structure ratio (d/a) and the refractive index contrast (Δn) of the magnetic fluids photonic crystals are deduced for band diagram calculations. The temperature-dependent band gaps are gained for z-even and z-odd modes. Band diagram calculations display that the mid frequencies and positions of the existing forbidden bands are not very sensitive to the temperature, while the number of the forbidden bands at certain strengths of magnetic field may change with the temperature variation. The results presented in this work give a guideline for designing the potential photonic devices based on the temperature characteristics of the magnetic fluids based photonic crystals and are helpful for improving their quality. - Highlights: → Mechanisms of temperature dependence of magnetic fluids based photonic crystals are elaborated. → Properties of existing forbidden bands have relatively fine temperature stability. → Disappearance of existing forbidden band is found for some magnetic fields. → Emergence of new forbidden band with temperature is found for some magnetic fields.

  10. Temperature dependence of the elastocaloric effect in natural rubber

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Zhongjian, E-mail: zhongjian.xie521@gmail.com; Sebald, Gael; Guyomar, Daniel

    2017-07-12

    The temperature dependence of the elastocaloric (eC) effect in natural rubber (NR) has been studied. This material exhibits a large eC effect over a broad temperature range from 0 °C to 49 °C. The maximum adiabatic temperature change (ΔT) occurred at 10 °C and the behavior could be predicted by the temperature dependence of the strain-induced crystallization (SIC) and the temperature-induced crystallization (TIC). The eC performance of NR was then compared with that of shape memory alloys (SMAs). This study contributes to the SIC research of NR and also broadens the application of elastomers. - Highlights: • A large elastocaloric effect over a broad temperature range was found in natural rubber (NR). • The caloric performance of NR was compared with that of shape memory alloys. • The temperature dependence of the elastocaloric effect in NR can be prediced by the theory of strain-induced crystallization.

  11. Strong association between corticosterone levels and temperature-dependent metabolic rate in individual zebra finches

    NARCIS (Netherlands)

    Jimeno Revilla, Blanca; Hau, Michaela; Verhulst, Simon

    2017-01-01

    Glucocorticoid hormones (GCs) are often assumed to be indicators of stress. At the same time, one of their fundamental roles is to facilitate metabolic processes to accommodate changes in energetic demands. Although the metabolic function of GCs is thought to be ubiquitous across vertebrates, we are

  12. The temperature--dependent expression of GST of Schistosoma japonicum (Philippine strain).

    Science.gov (United States)

    Cai, Z H; Song, G C; Xu, Y X; Liu, S X

    1993-03-01

    Obtained from pSj5, the cDNA gene encoding GST antigen of Schistosoma japonicum (Philippine strain) was ligated with efficient temperature-dependent PBV220 vector which was constructed in CAPM, and then introduced into host bacterium-DH5 alpha (E. coli) by transformation. Transformants were selected by ampicillin and recombinant clones were identified by restriction mapping. The result showed that recombinant clone 43 was the one carrying recombinant plasmid PBV 220 with the correct insertion of the gene fragment. The GST expression ability of clone 43 was investigated by GST enzymic activity assay and SDS-PAGE. A relatively high level of GST enzymic activity was expressed by this clone under the temperature-dependent condition, that is, cultured at 30 degrees C and expressed at 42 degrees C. A more strongly stained 26 kDa protein band was identified by SDS-PAGE. The result indicated that GST of S. japonicum (Philippine strain) could be expressed not only by IPTG induction, but also by the temperature-dependent method.

  13. Temperature dependence of the vibrational spectra of acetanilide: Davydov solitons or Fermi coupling

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, C.T.; Swanson, B.I.

    1985-03-15

    The unusual temperature dependence of the amide-I region in the IR spectrum of acetanilide (C/sub 6/H/sub 5/NHCOCH/sub 3/) has recently been attributed to a self-trapped Davydov-like soliton. The temperature dependence of the single-crystal Raman scattering from acetanilide and its N-D and /sup 13/C-O substituted analogs in the phonon and internal mode regions has now been studied. The behavior of the amide-I region in the Raman spectra of the normal isotopic species is similar to that observed earlier in infrared studies. However, on the basis of results obtained from the N-D and /sup 13/C-O substituted species the unusual temperature dependence in the 1650 cm/sup -1/ region has been attributed to Fermi coupling of the amide-I fundamental and a combination band involving the in-plane N-H deformation and a low-frequency torsional mode. As temperature is lowered, the strong blue-shift of the torsional mode results in a commensurate blue-shift in the combination level thereby increasing the Fermi coupling. Temperature tuning of the Fermi coupling results in the anomalous intensity changes observed in the IR and Raman spectra of the amide-I region for the normal isotopic species. 20 references, 3 figures.

  14. Temperature dependence of the vibrational spectra of acetanilide: Davydov solitons or Fermi coupling?

    Science.gov (United States)

    Johnston, Clifford T.; Swanson, Basil I.

    1985-03-01

    The unusual temperature dependence of the amide-I region in the IR spectrum of acetanilide (C 6H 5NHCOCH 3) has recently been attributed to a self-trapped Davydov-like soliton. The temperature dependence of the single-crystal Raman scattering, from acetanilide and its ND and 13CO substituted analogs in the phonon and internal mode regions has now been studied. The behavior of the amide-I region in the Raman spectra of the normal isotopic species is similar to that observed earlier in infrared studies. However, on the basis of results obtained from the ND and 13CO substituted species the unusual temperature dependence in the 1650 cm -1 region has been attributed to Fermi coupling of the amide-I fundamental and a combination band involving the in-plane NH deformation and a low-frequency torsional mode. As temperature is lowered, the strong blue-shift of the torsional mode results in a commensurate blue-shift in the combination level thereby increasing the Fermi coupling. Temperature tuning of the Fermi coupling results in the anomalous intensity changes observed in the IR and Raman spectra of the amide-I region for the normal isotopic species.

  15. Temperature dependence of the dynamics of zone boundary phonons in ZnO:Li

    Science.gov (United States)

    Yadav, Harish Kumar; Sreenivas, K.; Gupta, Vinay; Katiyar, R. S.

    2008-12-01

    Investigations of zone boundary phonons in ZnO:Li system (Li concentration: 10%) and their dynamics with temperature are reported. Additional modes at 127, 157, and 194 cm-1 are observed and assigned to zone boundary phonons at critical point M in the Brillouin zone [J. M. Calleja and M. Cardona, Phys. Rev. B 16, 3753 (1977)] due to breakdown of crystal translational symmetry with Li incorporation in ZnO. Anharmonicity in peak frequency and linewidth of the zone boundary phonons in a temperature range from 100 to 1000 K is also analyzed taking into account the decay of zone boundary phonons into three- and four-phonon modes (cubic and quadratic anharmonicities). The anharmonic behavior of peak frequency is found to be feebly dependent on three-phonon decay process but thermal expansion of lattice together with four-phonon decay process appropriately defines the temperature dependence. Linewidths, however, follow the simple four-phonon decay mechanism. E2(low) mode, on the other hand, shows a linear temperature dependency and therefore follows a three-phonon decay channel. The calculated values of phonon lifetimes at 100 K for the 127, 157, 194 cm-1, and E2(low) modes are 8.23, 6.54, 5.32, and 11.39 ps. Decay of the zone boundary phonon modes compared to E2(low) mode reveals that dopant induced disorder has a strong temperature dependency.

  16. Global patterns in lake ecosystem responses to warming based on the temperature dependence of metabolism.

    Science.gov (United States)

    Kraemer, Benjamin M; Chandra, Sudeep; Dell, Anthony I; Dix, Margaret; Kuusisto, Esko; Livingstone, David M; Schladow, S Geoffrey; Silow, Eugene; Sitoki, Lewis M; Tamatamah, Rashid; McIntyre, Peter B

    2017-05-01

    Climate warming is expected to have large effects on ecosystems in part due to the temperature dependence of metabolism. The responses of metabolic rates to climate warming may be greatest in the tropics and at low elevations because mean temperatures are warmer there and metabolic rates respond exponentially to temperature (with exponents >1). However, if warming rates are sufficiently fast in higher latitude/elevation lakes, metabolic rate responses to warming may still be greater there even though metabolic rates respond exponentially to temperature. Thus, a wide range of global patterns in the magnitude of metabolic rate responses to warming could emerge depending on global patterns of temperature and warming rates. Here we use the Boltzmann-Arrhenius equation, published estimates of activation energy, and time series of temperature from 271 lakes to estimate long-term (1970-2010) changes in 64 metabolic processes in lakes. The estimated responses of metabolic processes to warming were usually greatest in tropical/low-elevation lakes even though surface temperatures in higher latitude/elevation lakes are warming faster. However, when the thermal sensitivity of a metabolic process is especially weak, higher latitude/elevation lakes had larger responses to warming in parallel with warming rates. Our results show that the sensitivity of a given response to temperature (as described by its activation energy) provides a simple heuristic for predicting whether tropical/low-elevation lakes will have larger or smaller metabolic responses to warming than higher latitude/elevation lakes. Overall, we conclude that the direct metabolic consequences of lake warming are likely to be felt most strongly at low latitudes and low elevations where metabolism-linked ecosystem services may be most affected. © 2016 John Wiley & Sons Ltd.

  17. Complex temperature dependence of coupling and dissipation of cavity magnon polaritons from millikelvin to room temperature

    Science.gov (United States)

    Boventer, Isabella; Pfirrmann, Marco; Krause, Julius; Schön, Yannick; Kläui, Mathias; Weides, Martin

    2018-05-01

    Hybridized magnonic-photonic systems are key components for future information processing technologies such as storage, manipulation, or conversion of data both in the classical (mostly at room temperature) and quantum (cryogenic) regime. In this work, we investigate a yttrium-iron-garnet sphere coupled strongly to a microwave cavity over the full temperature range from 290 K to 30 mK . The cavity-magnon polaritons are studied from the classical to the quantum regimes where the thermal energy is less than one resonant microwave quanta, i.e., at temperatures below 1 K . We compare the temperature dependence of the coupling strength geff(T ) , describing the strength of coherent energy exchange between spin ensemble and cavity photon, to the temperature behavior of the saturation magnetization evolution Ms(T ) and find strong deviations at low temperatures. The temperature dependence of magnonic disspation is governed at intermediate temperatures by rare-earth impurity scattering leading to a strong peak at 40 K . The linewidth κm decreases to 1.2 MHz at 30 mK , making this system suitable as a building block for quantum electrodynamics experiments. We achieve an electromagnonic cooperativity in excess of 20 over the entire temperature range, with values beyond 100 in the millikelvin regime as well as at room temperature. With our measurements, spectroscopy on strongly coupled magnon-photon systems is demonstrated as versatile tool for spin material studies over large temperature ranges. Key parameters are provided in a single measurement, thus simplifying investigations significantly.

  18. A Temperature Dependent Lumped-charge Model for Trench FS-IGBT

    DEFF Research Database (Denmark)

    Duan, Yaoqiang; Kang, Yong; Iannuzzo, Francesco

    2018-01-01

    Abstract: This paper proposes a temperature dependent lumped-charge model for FS-IGBT. Due to the evolution of the IGBT structure, the existing lumped-charge IGBT model established for NPT-IGBT is not suitable for the simulation of FS-IGBT. This paper extends the lumped-charge IGBT model including...... the field-stop (FS) structure and temperature characteristics. The temperature characteristics of the model are considered for both the bipolar part and unipolar part. In addition, a new PN junction model which can distinguish the collector structure is presented and validated by TCAD simulation. Finally...

  19. On the Temperature Dependence of Enzyme-Catalyzed Rates.

    Science.gov (United States)

    Arcus, Vickery L; Prentice, Erica J; Hobbs, Joanne K; Mulholland, Adrian J; Van der Kamp, Marc W; Pudney, Christopher R; Parker, Emily J; Schipper, Louis A

    2016-03-29

    One of the critical variables that determine the rate of any reaction is temperature. For biological systems, the effects of temperature are convoluted with myriad (and often opposing) contributions from enzyme catalysis, protein stability, and temperature-dependent regulation, for example. We have coined the phrase "macromolecular rate theory (MMRT)" to describe the temperature dependence of enzyme-catalyzed rates independent of stability or regulatory processes. Central to MMRT is the observation that enzyme-catalyzed reactions occur with significant values of ΔCp(‡) that are in general negative. That is, the heat capacity (Cp) for the enzyme-substrate complex is generally larger than the Cp for the enzyme-transition state complex. Consistent with a classical description of enzyme catalysis, a negative value for ΔCp(‡) is the result of the enzyme binding relatively weakly to the substrate and very tightly to the transition state. This observation of negative ΔCp(‡) has important implications for the temperature dependence of enzyme-catalyzed rates. Here, we lay out the fundamentals of MMRT. We present a number of hypotheses that arise directly from MMRT including a theoretical justification for the large size of enzymes and the basis for their optimum temperatures. We rationalize the behavior of psychrophilic enzymes and describe a "psychrophilic trap" which places limits on the evolution of enzymes in low temperature environments. One of the defining characteristics of biology is catalysis of chemical reactions by enzymes, and enzymes drive much of metabolism. Therefore, we also expect to see characteristics of MMRT at the level of cells, whole organisms, and even ecosystems.

  20. Temperature dependent energy levels of methylammonium lead iodide perovskite

    Science.gov (United States)

    Foley, Benjamin J.; Marlowe, Daniel L.; Sun, Keye; Saidi, Wissam A.; Scudiero, Louis; Gupta, Mool C.; Choi, Joshua J.

    2015-06-01

    Temperature dependent energy levels of methylammonium lead iodide are investigated using a combination of ultraviolet photoemission spectroscopy and optical spectroscopy. Our results show that the valence band maximum and conduction band minimum shift down in energy by 110 meV and 77 meV as temperature increases from 28 °C to 85 °C. Density functional theory calculations using slab structures show that the decreased orbital splitting due to thermal expansion is a major contribution to the experimentally observed shift in energy levels. Our results have implications for solar cell performance under operating conditions with continued sunlight exposure and increased temperature.

  1. Temperature dependent energy levels of methylammonium lead iodide perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Benjamin J.; Marlowe, Daniel L.; Choi, Joshua J., E-mail: jjc6z@virginia.edu, E-mail: mgupta@virginia.edu, E-mail: scudiero@wsu.edu [Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Sun, Keye; Gupta, Mool C., E-mail: jjc6z@virginia.edu, E-mail: mgupta@virginia.edu, E-mail: scudiero@wsu.edu [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Saidi, Wissam A. [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States); Scudiero, Louis, E-mail: jjc6z@virginia.edu, E-mail: mgupta@virginia.edu, E-mail: scudiero@wsu.edu [Chemistry Department and Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164 (United States)

    2015-06-15

    Temperature dependent energy levels of methylammonium lead iodide are investigated using a combination of ultraviolet photoemission spectroscopy and optical spectroscopy. Our results show that the valence band maximum and conduction band minimum shift down in energy by 110 meV and 77 meV as temperature increases from 28 °C to 85 °C. Density functional theory calculations using slab structures show that the decreased orbital splitting due to thermal expansion is a major contribution to the experimentally observed shift in energy levels. Our results have implications for solar cell performance under operating conditions with continued sunlight exposure and increased temperature.

  2. Temperature-dependent luminescence dynamics in ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Priller, H. [Institut fuer Angewandte Physik, Universitaet Karlsruhe and Center for Functional Nanostructures (CFN), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany)]. E-mail: heiko.priller@physik.uni-karlsruhe.de; Hauschild, R. [Institut fuer Angewandte Physik, Universitaet Karlsruhe and Center for Functional Nanostructures (CFN), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Zeller, J. [Institut fuer Angewandte Physik, Universitaet Karlsruhe and Center for Functional Nanostructures (CFN), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Klingshirn, C. [Institut fuer Angewandte Physik, Universitaet Karlsruhe and Center for Functional Nanostructures (CFN), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Kalt, H. [Institut fuer Angewandte Physik, Universitaet Karlsruhe and Center for Functional Nanostructures (CFN), Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Kling, R. [Abteilung Halbleiterphysik, Universitaet Ulm, Albert-Einstein Allee 45, 89081 Ulm (Germany); Reuss, F. [Abteilung Halbleiterphysik, Universitaet Ulm, Albert-Einstein Allee 45, 89081 Ulm (Germany); Kirchner, Ch. [Abteilung Halbleiterphysik, Universitaet Ulm, Albert-Einstein Allee 45, 89081 Ulm (Germany); Waag, A. [Institut fuer Halbleitertechnik, TU Braunschweig, Hans-Sommer-Str. 66, D-38106 Braunschweig (Germany)

    2005-04-15

    We report on an experimental study of the temporal photoluminescence dynamics of high-quality ZnO nanopillars from 10 K to room temperature. We find that defect states play an important role in the time evolution of the photoluminescence signal. At low excitation intensities capture into defects dominates the time dependence of the PL, at higher intensities they are saturated and the intrinsic excitation decay is observed. We separate the intrinsic exciton decay from the fast nonlinear M-band with the method of decay associated spectra and obtain the temperature dependence of the intrinsic exciton decay. High excitation measurements show a reduced exciton-exciton scattering in these thin nanorods.

  3. Temperature Dependence of the Moessbauer Effect on Prussian Blue Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Pingheng; Xue Desheng; Luo Haiqing; Shi Huigang [Lanzhou University, Key Lab for Magnetism and Magnetic Materials of MOE (China)

    2002-09-15

    Highly ordered Prussian blue nanowires with diameter of about 50 nm and length up to 4 {mu}m have been fabricated by an electrodepositing technology with two-step anodizing anodic aluminum oxide films. The Moessbauer spectra taken between 15 and 300 K indicate that the hyperfine parameters decrease as the temperature increases. The temperature dependence of the quadrupole splitting, the isomer shift and the spectra area are discussed. A decrease of Debye temperature for Prussian blue nanowires was found with respect to that of Prussian blue bulk.

  4. Thermal Aware Floorplanning Incorporating Temperature Dependent Wire Delay Estimation

    DEFF Research Database (Denmark)

    Winther, AndreasThor; Liu, Wei; Nannarelli, Alberto

    2015-01-01

    Temperature has a negative impact on metal resistance and thus wire delay. In state-of-the-art VLSI circuits, large thermal gradients usually exist due to the uneven distribution of heat sources. The difference in wire temperature can lead to performance mismatch because wires of the same length...... can have different delay. Traditional floorplanning algorithms use wirelength to estimate wire performance. In this work, we show that this does not always produce a design with the shortest delay and we propose a floorplanning algorithm taking into account temperature dependent wire delay as one...

  5. Temperature dependence of acceptor-hole recombination in germanium

    International Nuclear Information System (INIS)

    Darken, L.S.; Jellison, G.E. Jr.

    1989-01-01

    The recombination kinetics of several centers (Zn - , Cu - , B - , CuH - 2 , CuH - x , Zn = , Cu = , and CuH = x ) in high-purity Ge have been measured as a function of temperature from 8 to 160 K by transient capacitance techniques and are significantly faster than expected from cascade theory. The cascade theory also gives the wrong temperature dependence, and the wrong z dependence. Instead, the data are generally fit by the expression N v /4pτ c congruent kT/h (p and τ c are, respectively, the free-hole concentration in the sample and the experimental mean capture time for a center)

  6. Temperature dependence of photovoltaic cells, modules, and systems

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Burdick, J.; Caiyem, Y. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    Photovoltaic (PV) cells and modules are often rated in terms of a set of standard reporting conditions defined by a temperature, spectral irradiance, and total irradiance. Because PV devices operates over a wide range of temperatures and irradiances, the temperature and irradiance related behavior must be known. This paper surveys the temperature dependence of crystalline and thin-film, state-of-the-art, research-size cells, modules, and systems measured by a variety of methods. The various error sources and measurement methods that contribute to cause differences in the temperature coefficient for a given cell or module measured with various methods are discussed.

  7. Temperature dependence of enthalpies and entropies of formation and migration of mono-vacancy in BCC iron

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Haohua; Woo, C.H., E-mail: chungho@cityu.edu.hk

    2014-12-15

    Entropies and enthalpies of vacancy formation and diffusion in BCC iron are calculated for each temperature directly from free-energies using phase-space trajectories obtained from spin–lattice dynamics simulations. Magnon contributions are found to be particularly substantial in the temperature regime near the α−β (ferro/para-magnetic) transition. Strong temperature dependence and singular behavior can be seen in this temperature regime, reflecting magnon softening effects. Temperature dependence of the lattice component in this regime is also much more significant compared to previous estimations based on Arrhenius-type fitting. Similar effects on activation processes involving other irradiation-produced defects in magnetic materials are expected.

  8. Determining Role of the Chain Mechanism in the Temperature Dependence of the Gas-Phase Rate of Combustion Reactions

    Science.gov (United States)

    Azatyan, V. V.; Bolod'yan, I. A.; Kopylov, N. P.; Kopylov, S. N.; Prokopenko, V. M.; Shebeko, Yu. N.

    2018-05-01

    It is shown that the strong dependence of the rate of gas-phase combustion reactions on temperature is determined by the high values of the reaction rate constants of free atoms and radicals. It is established that with a branched chain mechanism, a special role in the reaction rate temperature dependence is played by positive feedback between the concentrations of active intermediate species and the rate of their change. The role of the chemical mechanism in the temperature dependence of the process rate with and without inhibitors is considered.

  9. Temperature-dependent dynamical transitions of different classes of amino acid residue in a globular protein.

    Science.gov (United States)

    Miao, Yinglong; Yi, Zheng; Glass, Dennis C; Hong, Liang; Tyagi, Madhusudan; Baudry, Jerome; Jain, Nitin; Smith, Jeremy C

    2012-12-05

    The temperature dependences of the nanosecond dynamics of different chemical classes of amino acid residue have been analyzed by combining elastic incoherent neutron scattering experiments with molecular dynamics simulations on cytochrome P450cam. At T = 100-160 K, anharmonic motion in hydrophobic and aromatic residues is activated, whereas hydrophilic residue motions are suppressed because of hydrogen-bonding interactions. In contrast, at T = 180-220 K, water-activated jumps of hydrophilic side chains, which are strongly coupled to the relaxation rates of the hydrogen bonds they form with hydration water, become apparent. Thus, with increasing temperature, first the hydrophobic core awakens, followed by the hydrophilic surface.

  10. Temperature dependence of magnetization reversal in Co and Fe3O4 nanowire arrays

    International Nuclear Information System (INIS)

    Kazakova, Olga; Erts, Donats; Crowley, Timothy A.; Kulkarni, Jaideep S.; Holmes, Justin D.

    2005-01-01

    In this paper, we investigate the magnetization reversal of cobalt and magnetite nanowires, 4 nm in diameter, synthesized within the pores of mesoporous silica thin films. A SQUID magnetometer was used to study the magnetic properties of the nanowire arrays over a broad temperature interval, T=1.8-300 K. The magnetization reversal process was found to be strongly temperature dependent. While a coherent rotation may occur at room temperature, a process involving the formation of domain structures takes place as the temperature decreases down to 1.8 K

  11. Temperature dependence of autoxidation of perilla oil and tocopherol degradation.

    Science.gov (United States)

    Wang, Seonyeong; Hwang, Hyunsuk; Yoon, Sukhoo; Choe, Eunok

    2010-08-01

    Temperature dependence of the autoxidation of perilla oil and tocopherol degradation was studied with corn oil as a reference. The oils were oxidized in the dark at 20, 40, 60, and 80 degrees C. Oil oxidation was determined by peroxide and conjugated dienoic acid values. Tocopherols in the oils were quantified by HPLC. The oxidation of both oils increased with oxidation time and temperature. Induction periods for oil autoxidation decreased with temperature, and were longer in corn oil than in perilla oil, indicating higher sensitivity of perilla oil to oxidation. However, time lag for tocopherol degradation was longer in perilla oil, indicating higher stability of tocopherols in perilla oil than in corn oil. Activation energies for oil autoxidation and tocopherol degradation were higher in perilla oil (23.9 to 24.2, 9.8 kcal/mol, respectively) than in corn oil (12.5 to 15.8, 8.8 kcal/mol, respectively) indicating higher temperature-dependence in perilla oil. Higher stability of tocopherols in perilla oil was highly related with polyphenols. The study suggests that more careful temperature control is required to decrease the autoxidation of perilla oil than that of corn oil, and polyphenols contributed to the oxidative stability of perilla oil by protecting tocopherols from degradation, especially at the early stage of oil autoxidation.

  12. Temperature dependence of piezoelectric properties for textured SBN ceramics.

    Science.gov (United States)

    Kimura, Masahiko; Ogawa, Hirozumi; Kuroda, Daisuke; Sawada, Takuya; Higuchi, Yukio; Takagi, Hiroshi; Sakabe, Yukio

    2007-12-01

    Temperature dependences of piezoelectric properties were studied for h001i textured ceramics of bismuth layer-structured ferroelectrics, SrBi(2)Nb(2)O(9) (SBN). The textured ceramics with varied orientation degrees were fabricated by templated, grain-growth method, and the temperature dependences of resonance frequency were estimated. Excellent temperature stability of resonance frequency was obtained for the 76% textured ceramics. The resonance frequency of the 76% textured specimens varied almost linearly over a wide temperature range. Therefore, the variation was slight, even in a high temperature region above 150 degrees C. Temperature stability of a quartz crystal oscillator is generally higher than that of a ceramic resonator around room temperature. The variation of resonance frequency for the 76% textured SrBi(2)Nb(2)O(9) was larger than that of oscillation frequency for a typical quartz oscillator below 150 degrees C also in this study. However, the variation of the textured SrBi(2)Nb(2)O(9) was smaller than that of the quartz oscillator over a wide temperature range from -50 to 250 degrees C. Therefore, textured SrBi(2)Nb(2)O(9) ceramics is a major candidate material for the resonators used within a wide temperature range.

  13. Temperature-dependent imaging of living cells by AFM

    International Nuclear Information System (INIS)

    Espenel, Cedric; Giocondi, Marie-Cecile; Seantier, Bastien; Dosset, Patrice; Milhiet, Pierre-Emmanuel; Le Grimellec, Christian

    2008-01-01

    Characterization of lateral organization of plasma membranes is a prerequisite to the understanding of membrane structure-function relationships in living cells. Lipid-lipid and lipid-protein interactions are responsible for the existence of various membrane microdomains involved in cell signalization and in numerous pathologies. Developing approaches for characterizing microdomains associate identification tools like recognition imaging with high-resolution topographical imaging. Membrane properties are markedly dependent on temperature. However, mesoscopic scale topographical information of cell surface in a temperature range covering most of cell biology experimentation is still lacking. In this work we have examined the possibility of imaging the temperature-dependent behavior of eukaryotic cells by atomic force microscopy (AFM). Our results establish that the surface of living CV1 kidney cells can be imaged by AFM, between 5 and 37 deg. C, both in contact and tapping modes. These first temperature-dependent data show that large cell structures appeared essentially stable at a microscopic scale. On the other hand, as shown by contact mode AFM, the surface was highly dynamic at a mesoscopic scale, with marked changes in apparent topography, friction, and deflection signals. When keeping the scanning conditions constant, a progressive loss in the image contrast was however observed, using tapping mode, on decreasing the temperature

  14. Temperature-dependent structure evolution in liquid gallium

    International Nuclear Information System (INIS)

    Xiong, L.H.; Wang, X.D.; Yu, Q.; Zhang, H.; Zhang, F.; Sun, Y.; Cao, Q.P.; Xie, H.L.; Xiao, T.Q.; Zhang, D.X.; Wang, C.Z.; Ho, K.M.

    2017-01-01

    Temperature-dependent atomistic structure evolution of liquid gallium (Ga) has been investigated by using in situ high energy X-ray diffraction experiment and ab initio molecular dynamics simulation. Both experimental and theoretical results reveal the existence of a liquid structural change around 1000 K in liquid Ga. Below and above this temperature the liquid exhibits differences in activation energy for self-diffusion, temperature-dependent heat capacity, coordination numbers, density, viscosity, electric resistivity and thermoelectric power, which are reflected from structural changes of the bond-orientational order parameter Q_6, fraction of covalent dimers, averaged string length and local atomic packing. This finding will trigger more studies on the liquid-to-liquid crossover in metallic melts. - Graphical abstract: Atomistic structure evolution of liquid gallium has been investigated by using in situ high energy X-ray diffraction and ab initio molecular dynamics simulations, which both demonstrate the existence of a liquid structural change together with reported density, viscosity, electric resistivity and absolute thermoelectric power data.

  15. Temperature-dependent photoluminescence from CdS/Si nanoheterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yue Li; Li, Yong; Ji, Peng Fei; Zhou, Feng Qun; Sun, Xiao Jun; Yuan, Shu Qing; Wan, Ming Li [Pingdingshan University, Department of Physics, Solar New Energy Research Center, Pingdingshan (China); Ling, Hong [North China University of Water Resources and Electric Power, Department of Mathematics and Information Science, Zhengzhou (China)

    2016-12-15

    CdS/Si nanoheterojunctions have been fabricated by growing nanocrystal CdS (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) through using a chemical bath deposition method. The nanoheterojunctions have been constructed by three layers: the upper layer being a nc-CdS thin films, the intermediate layer being the interface region including nc-CdS and nanocrystal silicon (nc-Si), and the bottom layer being nc-Si layer grown on sc-Si substrate. The room temperature and temperature-dependent photoluminescence (PL) have been measured and analyzed to provide some useful information of defect states. Utilizing the Gauss-Newton fitting method, five emission peaks from the temperature-dependent PL spectra can be determined. From the high energy to low energy, these five peaks are ascribed to the some luminescence centers which are formed by the oxygen-related deficiency centers in the silicon oxide layer of Si-NPA, the band gap emission of nc-CdS, the transition from the interstitial cadmium (I{sub Cd}) to the valence band, the recombination from I{sub Cd} to cadmium vacancies (V{sub Cd}), and from sulfur vacancies (V{sub s}) to the valence band, respectively. Understanding of the defect states in the CdS/Si nanoheterojunctions is very meaningful for the performance of devices based on CdS/Si nanoheterojunctions. (orig.)

  16. Temperature-dependent electrical property transition of graphene oxide paper

    International Nuclear Information System (INIS)

    Huang Xingyi; Jiang Pingkai; Zhi Chunyi; Golberg, Dmitri; Bando, Yoshio; Tanaka, Toshikatsu

    2012-01-01

    Reduction of graphene oxide is primarily important because different reduction methods may result in graphene with totally different properties. For systematically exploring the reduction of graphene oxide, studies of the temperature-dependent electrical properties of graphene oxide (GO) are urgently required. In this work, for the first time, broadband dielectric spectroscopy was used to carry out an in situ investigation on the transition of the electrical properties of GO paper from −40 to 150 °C. The results clearly reveal a very interesting four-stage transition of electrical properties of GO paper with increasing temperature: insulator below 10 °C (stage 1), semiconductor at between 10 and 90 °C (stage 2), insulator at between 90 and 100 °C (stage 3), and semiconductor again at above 100 °C (stage 4). Subsequently, the transition mechanism was discussed in combination with detailed dielectric properties, microstructure and thermogravimetric analyses. It is suggested that the temperature-dependent transition of electronic properties of GO is closely associated with the ion mobility, water molecules removal and the reduction of GO in the GO paper. Most importantly, the present work clearly demonstrates the reduction of GO paper starts at above 100 °C. (paper)

  17. Temperature dependence and the moving species during ion mixing

    International Nuclear Information System (INIS)

    Xia, W.; Fernandes, M.; Hewett, C.A.; Lau, S.S.; Poker, D.B.; Biersack, J.P.

    1988-01-01

    In this paper, the authors review the experimental observations of the temperature dependence and the moving species in ion mixing, emphasizing the metal-semiconductor systems. Ion mixing is the combined effect of two components. One component is temperature independent and is primarily due to events in the prompt regime, the other component is temperature dependent and has the characteristics of the associated thermal reactions. The moving species during ion mixing are influenced by collisional effects, either due to secondary recoils, or due to local hot spots, or both. The secondary recoil concept is consistent with experimental observations that the motion of the lighter element in a bilayer sample is enhanced. There is ample evidence that while the a thermal regime is caused by particle-solid interactions, thermodynamical forces are important in deciding the magnitude of mixing. In the thermally activated regime, the ion induced reaction product should be influenced by the heats of formation of various compounds. We also indicate areas where satisfactory explanations are not available at present

  18. Temperature dependence of carbon isotope fractionation in CAM plants

    International Nuclear Information System (INIS)

    Deleens, E.; Treichel, I.; O'Leary, M.H.

    1985-01-01

    The carbon isotope fractionation associated with nocturnal malic acid synthesis in Kalanchoë daigremontiana and Bryophyllum tubiflorum was calculated from the isotopic composition of carbon-4 of malic acid, after appropriate corrections. In the lowest temperature treatment (17 degrees C nights, 23 degrees C days), the isotope fractionation for both plants is -4 per thousand (that is, malate is enriched in (13)C relative to the atmosphere). For K. daigremontiana, the isotope fractionation decreases with increasing temperature, becoming approximately 0 per thousand at 27 degrees C/33 degrees C. Detailed analysis of temperature effects on the isotope fractionation indicates that stomatal aperture decreases with increasing temperature and carboxylation capacity increases. For B. tubiflorum, the temperature dependence of the isotope fractionation is smaller and is principally attributed to the normal temperature dependences of the rates of diffusion and carboxylation steps. The small change in the isotopic composition of remaining malic acid in both species which is observed during deacidification indicates that malate release, rather than decarboxylation, is rate limiting in the deacidification process

  19. Temperature dependence of carbon isotope fractionation in CAM plants

    Energy Technology Data Exchange (ETDEWEB)

    Deleens, E.; Treichel, I.; O' Leary, M.H.

    1985-09-01

    The carbon isotope fractionation associated with nocturnal malic acid synthesis in Kalanchoe daigremontiana and Bryophyllum tubiflorum was calculated from the isotopic composition of carbon-4 of malic acid, after appropriate corrections. In the lowest temperature treatment (17/sup 0/C nights, 23/sup 0/C days), the isotope fractionation for both plants is -4% per thousand (that is, malate is enriched in /sup 13/C relative to the atmosphere). For K. daigremontiana, the isotope fractionation decreases with increasing temperature, becoming approximately 0% per thousand at 27/sup 0/C/33/sup 0/C. Detailed analysis of temperature effects on the isotope fractionation indicates that stomatal aperture decreases with increasing temperature and carboxylation capacity increases. For B. tubiflorum, the temperature dependence of the isotope fractionation is smaller and is principally attributed to the normal temperature dependences of the rates of diffusion and carboxylation steps. The small change in the isotopic composition of remaining malic acid in both species which is observed during deacidification indicates that malate release, rather than decarboxylation, is rate limiting in the deacidification process. 28 references, 1 figure, 4 tables.

  20. Temperature dependence of exchange bias in (NiFe/IrMn)n multilayer films studied through static and dynamic techniques

    Science.gov (United States)

    Adams, Daniel J.; Khanal, Shankar; Khan, Mohammad Asif; Maksymov, Artur; Spinu, Leonard

    2018-05-01

    The in-plane temperature dependence of exchange bias was studied through both dc magnetometry and ferromagnetic resonance spectroscopy in a series of [NiFe/IrMn]n multilayer films, where n is the number of layer repetitions. Major hysteresis loops were recorded in the temperature range of 300 K to 2 K to reveal the effect of temperature on the exchange bias in the static regime while temperature-dependent continuous-wave ferromagnetic resonance for frequencies from 3 to 16 GHz was used to determine the exchange bias dynamically. Strong divergence between the values of exchange bias determined using the two different types of measurements as well as a peak in temperature dependence of the resonance linewidth were observed. These results are explained in terms of the slow-relaxer mechanism.

  1. Temperature dependence of low-frequency polarized Raman scattering spectra in TlInS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Paucar, Raul; Wakita, Kazuki [Electronics and Computer Engineering, Chiba Institute of Technology, Chiba (Japan); Shim, YongGu; Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, Osaka (Japan); Alekperov, Oktay; Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan)

    2017-06-15

    In this work, we examined phase transitions in the layered ternary thallium chalcogenide TlInS{sub 2} by studying the temperature dependence of polarized Raman spectra with the aid of the Raman confocal microscope system. The Raman spectra were measured over the temperature range of 77-320 K (which includes the range of successive phase transitions) in the low-frequency region of 35-180 cm{sup -1}. The optical phonons that showed strong temperature dependence were identified as interlayer vibrations related to phase transitions, while the phonons that showed weak temperature dependence were identified as intralayer vibrations. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Effect of linear and non-linear components in the temperature dependences of thermoelectric properties on the energy conversion efficiency

    International Nuclear Information System (INIS)

    Yamashita, Osamu

    2009-01-01

    The new thermal rate equations were built up by taking the linear and non-linear components in the temperature dependences of the Seebeck coefficient α, the electrical resistivity ρ and thermal conductivity κ of a thermoelectric (TE) material into the thermal rate equations on the assumption that their temperature dependences are expressed by a quadratic function of temperature T. The energy conversion efficiency η for a single TE element was formulated using the new thermal rate ones proposed here. By applying it to the high-performance half-Heusler compound, the non-linear component in the temperature dependence of α among those of the TE properties has the greatest effect on η, so that η/η 0 was increased by 11% under the condition of T = 510 K and ΔT = 440 K, where η 0 is a well-known conventional energy conversion efficiency. It was thus found that the temperature dependences of TE properties have a significant influence on η. When one evaluates the accurate achievement rate of η exp obtained experimentally for a TE generator, therefore, η exp should be compared with η the estimated from the theoretical expression proposed here, not with η 0 , particularly when there is a strong non-linearity in the temperature dependence of TE properties.

  3. Gas diffusion and temperature dependence of bubble nucleation during irradiation

    DEFF Research Database (Denmark)

    Foreman, A. J. E.; Singh, Bachu Narain

    1986-01-01

    The continuous production of gases at relatively high rates under fusion irradiation conditions may enhance the nucleation of cavities. This can cause dimensional changes and could induce embrittlement arising from gas accumulation on grain boundaries. Computer calculations have been made...... of the diatomic nucleation of helium bubbles, assuming helium to diffuse substitutionally, with radiation-enhanced diffusion at lower temperatures. The calculated temperature dependence of the bubble density shows excellent agreement with that observed in 600 MeV proton irradiations, including a reduction...... in activation energy below Tm/2. The coalescence of diatomic nuclei due to Brownian motion markedly improves the agreement and also provides a well-defined terminal density. Bubble nucleation by this mechanism is sufficiently fast to inhibit any appreciable initial loss of gas to grain boundaries during...

  4. Temperature dependence of contact resistance at metal/MWNT interface

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang-Eui; Moon, Kyoung-Seok; Sohn, Yoonchul, E-mail: yoonchul.son@samsung.com [Materials Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon 443-803 (Korea, Republic of)

    2016-07-11

    Although contact resistance of carbon nanotube (CNT) is one of the most important factors for practical application of electronic devices, a study regarding temperature dependence on contact resistance of CNTs with metal electrodes has not been found. Here, we report an investigation of contact resistance at multiwalled nanotube (MWNT)/Ag interface as a function of temperature, using MWNT/polydimethylsiloxane (PDMS) composite. Electrical resistance of MWNT/PDMS composite revealed negative temperature coefficient (NTC). Excluding the contact resistance with Ag electrode, the NTC effect became less pronounced, showing lower intrinsic resistivity with the activation energy of 0.019 eV. Activation energy of the contact resistance of MWNT/Ag interface was determined to be 0.04 eV, two times larger than that of MWNT-MWNT network. The increase in the thermal fluctuation assisted electron tunneling is attributed to conductivity enhancement at both MWNT/MWNT and MWNT/Ag interfaces with increasing temperature.

  5. Determination of the temperature dependence of tungsten erosion

    International Nuclear Information System (INIS)

    Maier, H.; Greuner, H.; Toussaint, U. von; Balden, M.; Böswirth, B.; Elgeti, S.

    2015-01-01

    We present the results of erosion measurements on actively cooled tungsten samples at quasi-constant surface temperature conditions performed in the high heat flux facility GLADIS. The samples were exposed to a H beam at a central power density of 10 MW/m 2 up to a fluence of 10 26 m −2 . We observe a weak temperature dependence of the erosion yield. The data are compared with similar data obtained from loading with a H beam with He admixture. Both datasets are analysed in a probabilistic approach. We obtain activation energies of 0.04 eV and 0.06 eV for the cases with and without He, respectively

  6. Temperature-dependent liquid metal flowrate control device

    International Nuclear Information System (INIS)

    Carlson, R.D.

    1978-01-01

    A temperature-dependent liquid metal flowrate control device includes a magnet and a ferromagnetic member defining therebetween a flow path for liquid metal, the ferromagnetic member being formed of a material having a curie temperature at which a change in the flow rate of the liquid metal is desired. According to the preferred embodiment the magnet is a cylindrical rod magnet axially disposed within a cylindrical member formed of a curie material and having iron pole pieces at the ends. A cylindrical iron shunt and a thin wall stainless steel barrier are disposed in the annulus between magnet and curie material. Below the curie temperature flow between steel barrier and curie material is impeded and above the curie temperature flow impedance is reduced

  7. Temperature dependence of bulk viscosity in water using acoustic spectroscopy

    International Nuclear Information System (INIS)

    Holmes, M J; Parker, N G; Povey, M J W

    2011-01-01

    Despite its fundamental role in the dynamics of compressible fluids, bulk viscosity has received little experimental attention and there remains a paucity of measured data. Acoustic spectroscopy provides a robust and accurate approach to measuring this parameter. Working from the Navier-Stokes model of a compressible fluid one can show that the bulk viscosity makes a significant and measurable contribution to the frequency-squared acoustic attenuation. Here we employ this methodology to determine the bulk viscosity of Millipore water over a temperature range of 7 to 50 0 C. The measured attenuation spectra are consistent with the theoretical predictions, while the bulk viscosity of water is found to be approximately three times larger than its shear counterpart, reinforcing its significance in acoustic propagation. Moreover, our results demonstrate that this technique can be readily and generally applied to fluids to accurately determine their temperature dependent bulk viscosities.

  8. Temperature dependent structural and vibrational properties of liquid indium

    Science.gov (United States)

    Patel, A. B.; Bhatt, N. K.

    2018-05-01

    The influence of the temperature effect on both the structure factor and the phonon dispersion relation of liquid indium have been investigated by means of pseudopotential theory. The Percus-Yevick Hard Sphere reference system is applied to describe the structural calculation. The effective electron-ion interaction is explained by using modified empty core potential due to Hasegawa et al. along with a local field correction function due to Ichimaru-Utsumi (IU). The temperature dependence of pair potential needed at higher temperatures was achieved by multiplying the damping factor exp(- π/kBT2k F r ) in the pair potential. Very close agreement of static structure factor, particularly, at elevated temperatures confirms the validity of the local potential. A positive dispersion is found in low-q region and the correct trend of phonon dispersion branches like the experimental; shows all broad features of collective excitations in liquid metals.

  9. Temperature-dependent chemical changes of metallic fuel

    Energy Technology Data Exchange (ETDEWEB)

    Youn, Young Sang; Lee, Jeong Mook; KimJong Hwan; Song, Hoon; Kim, Jong Yun [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    We observed the temperature-dependent variations of UZr alloy using surface analysis techniques such as X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscope (SEM) equipped with energy-dispersive Xray spectroscope (EDS). In this work, we exhibited the results of XPS, Raman, XRD, and SEM-EDS for U-10wt%Zr alloy at room temperature, 610 and 1130 .deg. C. In SEM-EDS data, we observed that uranium and zirconium elements uniformly exist. After the annealing of U-10Zr sample at 1130 .deg. C, the formation of zirconium carbide is verified through Raman spectroscopy and XRD results. Additionally, the change of valence state for uranium element is also confirmed by XPS analysis.

  10. Temperature-dependence of the QCD topological susceptibility

    Science.gov (United States)

    Kovacs, Tamas G.

    2018-03-01

    We recently obtained an estimate of the axion mass based on the hypothesis that axions make up most of the dark matter in the universe. A key ingredient for this calculation was the temperature-dependence of the topological susceptibility of full QCD. Here we summarize the calculation of the susceptibility in a range of temperatures from well below the finite temperature cross-over to around 2 GeV. The two main difficulties of the calculation are the unexpectedly slow convergence of the susceptibility to its continuum limit and the poor sampling of nonzero topological sectors at high temperature. We discuss how these problems can be solved by two new techniques, the first one with reweighting using the quark zero modes and the second one with the integration method.

  11. Temperature dependence of muonium reaction rates in the gas phase

    International Nuclear Information System (INIS)

    Fleming, D.G.; Garner, D.M.; Mikula, R.J.; British Columbia Univ., Vancouver

    1981-01-01

    A study of the temperature dependence of reaction rates has long been an important tool in establishing reaction pathways in chemical reactions. This is particularly true for the reactions of muonium (in comparison with those of hydrogen) since a measurement of the activation energy for chemical reaction is sensitive to both the height and the position of the potential barrier in the reaction plane. For collision controlled reactions, on the other hand, the reaction rate is expected to exhibit a weak T 1 sup(/) 2 dependence characteristic of the mean collision velocity. These concepts are discussed and their effects illustrated in a comparison of the chemical and spin exchange reaction rates of muonium and hydrogen in the temperature range approx.300-approx.500 K. (orig.)

  12. Temperature-dependent particle-number projected moment of inertia

    International Nuclear Information System (INIS)

    Allal, N. H.; Fellah, M.; Benhamouda, N.; Oudih, M. R.

    2008-01-01

    Expressions of the parallel and perpendicular temperature-dependent particle-number projected nuclear moment of inertia have been established by means of a discrete projection method. They generalize that of the FTBCS method and are well adapted to numerical computation. The effects of particle-number fluctuations have been numerically studied for some even-even actinide nuclei by using the single-particle energies and eigenstates of a deformed Woods-Saxon mean field. It has been shown that the parallel moment of inertia is practically not modified by the use of the projection method. In contrast, the discrepancy between the projected and FTBCS perpendicular moment of inertia values may reach 5%. Moreover, the particle-number fluctuation effects vary not only as a function of the temperature but also as a function of the deformation for a given temperature. This is not the case for the system energy

  13. Temperature dependence of magnetoresistance in copper single crystals

    Science.gov (United States)

    Bian, Q.; Niewczas, M.

    2018-03-01

    Transverse magnetoresistance of copper single crystals has been measured in the orientation of open-orbit from 2 K to 20 K for fields up to 9 T. The experimental Kohler's plots display deviation between individual curves below 16 K and overlap in the range of 16 K-20 K. The violation of the Kohler's rule below 16 K indicates that the magnetotransport can not be described by the classical theory of electron transport on spherical Fermi surface with a single relaxation time. A theoretical model incorporating two energy bands, spherical and cylindrical, with different relaxation times has been developed to describe the magnetoresistance data. The calculations show that the electron-phonon scattering rates at belly and neck regions of the Fermi surface have different temperature dependencies, and in general, they do not follow T3 law. The ratio of the relaxation times in belly and neck regions decreases parabolically with temperature as A - CT2 , with A and C being constants.

  14. Temperature-dependent μ-Raman investigation of struvite crystals.

    Science.gov (United States)

    Prywer, Jolanta; Kasprowicz, D; Runka, T

    2016-04-05

    The effect of temperature on the vibrational properties of struvite crystals grown from silica gels was systematically studied by μ-Raman spectroscopy. The time-dependent Raman spectra recorded in the process of long time annealing of struvite crystal at 353 K do not indicate structural changes in the struvite crystal with the time of annealing. The temperature-dependent Raman spectra recorded in the range 298-423 K reveal a phase transition in struvite at about 368 K. Above this characteristic temperature, some of bands assigned to vibrations of the PO4 and NH4 tetrahedra and water molecules observed in the Raman spectra in low temperatures (orthorhombic phase) change their spectral parameters or disappear, which indicates a transition to a higher symmetry structure of struvite in the range of high temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Temperature Dependent Variations of Phonon Interactions in Nanocrystalline Cerium Oxide

    Directory of Open Access Journals (Sweden)

    Sugandha Dogra Pandey

    2015-01-01

    Full Text Available The temperature dependent anharmonic behavior of the phonon modes of nanocrystalline CeO2 was investigated in the temperature range of 80–440 K. The anharmonic constants have been derived from the shift in phonon modes fitted to account for the anharmonic contributions as well as the thermal expansion contribution using the high pressure parameters derived from our own high pressure experimental data reported previously. The total anharmonicity has also been estimated from the true anharmonicity as well as quasiharmonic component. In the line-width variation analysis, the cubic anharmonic term was found to dominate the quartic term. Finally, the phonon lifetime also reflected the trend so observed.

  16. Temperature dependence of the electronic structure of semiconductors and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Poncé, S., E-mail: samuel.pon@gmail.com; Gillet, Y.; Laflamme Janssen, J.; Gonze, X. [European Theoretical Spectroscopy Facility and Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Chemin des étoiles 8, bte L07.03.01, B-1348 Louvain-la-neuve (Belgium); Marini, A. [Consiglio Nazionale delle Ricerche (CNR), Via Salaria Km 29.3, CP 10, 00016 Monterotondo Stazione (Italy); Verstraete, M. [European Theoretical Spectroscopy Facility and Physique des matériaux et nanostructures, Université de Liège, Allée du 6 Août 17, B-4000 Liège (Belgium)

    2015-09-14

    The renormalization of electronic eigenenergies due to electron-phonon coupling (temperature dependence and zero-point motion effect) is sizable in many materials with light atoms. This effect, often neglected in ab initio calculations, can be computed using the perturbation-based Allen-Heine-Cardona theory in the adiabatic or non-adiabatic harmonic approximation. After a short description of the recent progresses in this field and a brief overview of the theory, we focus on the issue of phonon wavevector sampling convergence, until now poorly understood. Indeed, the renormalization is obtained numerically through a slowly converging q-point integration. For non-zero Born effective charges, we show that a divergence appears in the electron-phonon matrix elements at q → Γ, leading to a divergence of the adiabatic renormalization at band extrema. This problem is exacerbated by the slow convergence of Born effective charges with electronic wavevector sampling, which leaves residual Born effective charges in ab initio calculations on materials that are physically devoid of such charges. Here, we propose a solution that improves this convergence. However, for materials where Born effective charges are physically non-zero, the divergence of the renormalization indicates a breakdown of the adiabatic harmonic approximation, which we assess here by switching to the non-adiabatic harmonic approximation. Also, we study the convergence behavior of the renormalization and develop reliable extrapolation schemes to obtain the converged results. Finally, the adiabatic and non-adiabatic theories, with corrections for the slow Born effective charge convergence problem (and the associated divergence) are applied to the study of five semiconductors and insulators: α-AlN, β-AlN, BN, diamond, and silicon. For these five materials, we present the zero-point renormalization, temperature dependence, phonon-induced lifetime broadening, and the renormalized electronic band structure.

  17. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    International Nuclear Information System (INIS)

    Singh, Akhilesh Kumar; Hsu, Jen-Hwa; Perumal, Alagarsamy

    2016-01-01

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)] 2 /FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (T A =200, 300 and 400 °C). Structural analyzes reveal that the films annealed at T A ≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at T A =300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M–H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), T A and temperature. A large reduction in coercivity (H C ) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of H C (T), i.e., a broad minimum in H C (T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the H C (T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (T C ) with T A (x). The multilayer films annealed at 200 °C exhibit low value of T C with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest T C with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and nature of interfaces. - Highlights: • Preparation and

  18. Temperature Dependences of Mechanisms Responsible for the Water-Vapor Continuum Absorption

    Science.gov (United States)

    Ma, Qiancheng

    2014-01-01

    The water-vapor continuum absorption plays an important role in the radiative balance in the Earth's atmosphere. It has been experimentally shown that for ambient atmospheric conditions, the continuum absorption scales quadratically with the H2O number density and has a strong, negative temperature dependence (T dependence). Over the years, there have been three different theoretical mechanisms postulated: far-wings of allowed transition lines, water dimers, and collision-induced absorption. The first mechanism proposed was the accumulation of absorptions from the far-wings of the strong allowed transition lines. Later, absorption by water dimers was proposed, and this mechanism provides a qualitative explanation for the continuum characters mentioned above. Despite the improvements in experimental data, at present there is no consensus on which mechanism is primarily responsible for the continuum absorption.

  19. The temperature dependent strontium isotope fractionation (δ88/86Sr) during calcium carbonate precipitation

    International Nuclear Information System (INIS)

    Fietzke, J.; Eisenhauer, A.

    2006-01-01

    Full text: In order to study the influence of stable isotope fractionation during inorganic and biologically controlled CaCO 3 precipitation we have developed the analytical principles for the measurement of strontium (Sr) isotope fractionation. We have established a measurement protocol for the application on a MC-ICP-MS (AXIOM) using the common bracketing standard technique. The Sr-standard CRM NBS987 was used as reference material for all measurements and to calculate the Sr fractionation. Latter value is expressed by the δ-notation defined as: δ 88/86 Sr = [( 88 Sr/ 86 Sr)sample / ( 88 Sr/ 86 Sr)standard ] * 1000 -1. A first set of experiments focused on the temperature dependency of Sr-isotope fractionation. For this purpose inorganically precipitated aragonite and calcite was prepared under controlled conditions in a temperature range from 10 to 50 o C. In addition, cultured and naturally grown corals were analyzed for their δ 88/86 Sr values. Repeated measurements of IAPSO seawater standard showed a mean δ 88/86 Sr value of 0.383 ± 0.008 (2 SEM) being the isotopically heaviest material measured so far. The first results of the inorganically precipitated aragonite and the natural corals revealed a clear temperature dependency of the δ 88/86 Sr values. For inorganic aragonite the slope of this correlation is about 0.0055 permil/ o C. However, for naturally grown corals (Pavona clavus) a 6 fold steeper slope of 0.033 permil/ o C was determined. This strong temperature dependency implies the potential to use stable Sr isotopes as a new marine (paleo)temperature proxy. (author)

  20. The temperature dependences of electromechanical properties of PLZT ceramics

    Science.gov (United States)

    Czerwiec, M.; Zachariasz, R.; Ilczuk, J.

    2008-02-01

    The mechanical and electrical properties in lanthanum modified lead zirconate-titanate ceramics of 5/50/50 and 10/50/50 were studied by mechanical loss Q - 1, Young's modulus E, electric permittivity ɛ and tangent of dielectric loss of angle tgδ measurements. The internal friction Q - 1 and Young modulus E measured from 290 K to 600 K shows that Curie temperature TC is located at 574 K and 435 K (1st cycle of heating) respectively for ceramic samples 5/50/50 and 10/50/50. The movement of TC in second cycle of heating to lower temperature (561 K for 5/50/50 and 420 K for 10/50/50) has been observed. Together with Q - 1 and E measurements, temperature dependences of ɛ=f(T) and tgδ=f(T) were determinated in temperature range from 300 K to 730 K. The values of TC obtained during ɛ and tgδ measurements were respectively: 560 K for 5/50/50 and 419 K for 10/50/50. These temperatures are almost as high as the temperatures obtained by internal friction Q - 1 measurements in second cycle of heating. In ceramic sample 10/50/50 the additional maximum on internal friction Q - 1 curve at the temperature 316 K was observed.

  1. Temperature dependence of thermal pressure for NaCl

    Science.gov (United States)

    Singh, Chandra K.; Pande, Brijesh K.; Pandey, Anjani K.

    2018-05-01

    Engineering applications of the materials can be explored upto the desired limit of accuracy with the better knowledge of its mechanical and thermal properties such as ductility, brittleness and Thermal Pressure. For the resistance to fracture (K) and plastic deformation (G) the ratio K/G is treated as an indication of ductile or brittle character of solids. In the present work we have tested the condition of ductility and brittleness with the calculated values of K/G for the NaCl. It is concluded that the nature of NaCl can be predicted upto high temperature simply with the knowledge of its elastic stiffness constant only. Thermoelastic properties of materials at high temperature is directly related to thermal pressure and volume expansion of the materials. An expression for the temperature dependence of thermal pressure is formulated using basic thermodynamic identities. It is observed that thermal pressure ΔPth calculated for NaCl by using Kushwah formulation is in good agreement with the experimental values also the thermal pressure increases with the increase in temperature.

  2. Temperature-dependent binding of cyclosporine to an erythrocyte protein

    International Nuclear Information System (INIS)

    Agarwal, R.P.; Threatte, G.A.; McPherson, R.A.

    1987-01-01

    In this competitive binding assay to measure endogenous binding capacity for cyclosporine (CsA) in erythrocyte lysates, a fixed amount of [ 3 H]CsA plus various concentrations of unlabeled CsA is incubated with aliquots of a test hemolysate. Free CsA is then adsorbed onto charcoal and removed by centrifugation; CsA complexed with a cyclosporine-binding protein (CsBP) remains in the supernate. We confirmed the validity of this charcoal-separation mode of binding analysis by comparison with equilibrium dialysis. Scatchard plot analysis of the results at 4 degrees C yielded a straight line with slope corresponding to a binding constant of 1.9 X 10(7) L/mol and a saturation capacity of approximately 4 mumol per liter of packed erythrocytes. Similar analysis of binding data at 24 degrees C and 37 degrees C showed that the binding constant decreased with increasing temperature, but the saturation capacity did not change. CsBP was not membrane bound but appeared to be freely distributed within erythrocytes. 125 I-labeled CsA did not complex with the erythrocyte CsBP. Several antibiotics and other drugs did not inhibit binding between CsA and CsBP. These findings may explain the temperature-dependent uptake of CsA by erythrocytes in whole blood and suggest that measurement of CsBP in erythrocytes or lymphocytes may help predict therapeutic response or toxicity after administration of CsA

  3. Temperature dependent quasiparticle renormalization in nickel and iron

    Energy Technology Data Exchange (ETDEWEB)

    Ovsyannikov, Ruslan; Thirupathaiah, Setti; Sanchez-Barriga, Jaime; Fink, Joerg; Duerr, Hermann [Helmholtz Zentrum Berlin, BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany)

    2010-07-01

    One of the fundamental consequences of electron correlation effects is that the bare particles in solids become 'dressed' with an excitation cloud resulting in quasiparticles. Such a quasiparticle will carry the same spin and charge as the original particle, but will have a renormalized mass and a finite lifetime. The properties of many-body interactions are described with a complex function called self energy which is directly accessible to modern high-resolution angle resolved photoemission spectroscopy (ARPES). Ferromagnetic metals like nickel or iron offers the exciting possibility to study the spin dependence of quasiparticle coupling to bosonic modes. Utilizing the exchange split band structure as an intrinsic 'spin detector' it is possible to distinguish between electron-phonon and electron-magnon coupling phenomena. In this contribution we will report a systematic investigation of the k- and temperature dependence of the electron-boson coupling in nickel and iron metals as well as discuss origin of earlier observed anomalous lifetime broadening of majority spin states of nickel at Fermi level.

  4. Modeling temperature dependent singlet exciton dynamics in multilayered organic nanofibers

    Science.gov (United States)

    de Sousa, Leonardo Evaristo; de Oliveira Neto, Pedro Henrique; Kjelstrup-Hansen, Jakob; da Silva Filho, Demétrio Antônio

    2018-05-01

    Organic nanofibers have shown potential for application in optoelectronic devices because of the tunability of their optical properties. These properties are influenced by the electronic structure of the molecules that compose the nanofibers and also by the behavior of the excitons generated in the material. Exciton diffusion by means of Förster resonance energy transfer is responsible, for instance, for the change with temperature of colors in the light emitted by systems composed of different types of nanofibers. To study in detail this mechanism, we model temperature dependent singlet exciton dynamics in multilayered organic nanofibers. By simulating absorption and emission spectra, the possible Förster transitions are identified. Then, a kinetic Monte Carlo model is employed in combination with a genetic algorithm to theoretically reproduce time-resolved photoluminescence measurements for several temperatures. This procedure allows for the obtainment of different information regarding exciton diffusion in such a system, including temperature effects on the Förster transfer efficiency and the activation energy of the Förster mechanism. The method is general and may be employed for different systems where exciton diffusion plays a role.

  5. A model for temperature dependent resistivity of metallic superlattices

    Directory of Open Access Journals (Sweden)

    J. I. Uba

    2015-11-01

    Full Text Available The temperature dependent resistivity of metallic superlattices, to first order approximation, is assumed to have same form as bulk metal, ρ(T = ρo + aT, which permits describing these structures as linear atomic chain. The assumption is, substantiated with the derivation of the above expression from the standard magnetoresistance equation, in which the second term, a Bragg scattering factor, is a correction to the usual model involving magnon and phonon scatterings. Fitting the model to Fe/Cr data from literature shows that Bragg scattering is dominant at T < 50 K and magnon and phonon coefficients are independent of experiment conditions, with typical values of 4.7 × 10−4 μΩcmK−2 and −8 ± 0.7 × 10−7μΩcmK−3. From the linear atomic chain model, the dielectric constant ε q , ω = 8 . 33 × 10 − 2 at Debye frequency for all materials and acoustic speed and Thomas – Fermi screening length are pressure dependent with typical values of 1.53 × 104 m/s and 1.80 × 109 m at 0.5 GPa pressure for an Fe/Cr structure.

  6. Temperature-Dependent Dielectric Properties of Al/Epoxy Nanocomposites

    Science.gov (United States)

    Wang, Zijun; Zhou, Wenying; Sui, Xuezhen; Dong, Lina; Cai, Huiwu; Zuo, Jing; Chen, Qingguo

    2016-06-01

    Broadband dielectric spectroscopy was carried out to study the transition in electrical properties of Al/epoxy nanocomposites over the frequency range of 1-107 Hz and the temperature range of -20°C to 200°C. The dielectric permittivity, dissipation factor, and electrical conductivity of the nanocomposites increased with temperature and showed an abrupt increase around the glass transition temperature ( T g). The results clearly reveal an interesting transition of the electrical properties with increasing temperature: insulator below 70°C, conductor at about 70°C. The behavior of the transition in electrical properties of the nanocomposites was explored at different temperatures. The presence of relaxation peaks in the loss tangent and electric modulus spectra of the nanocomposites confirms that the chain segmental dynamics of the polymer is accompanied by the absorption of energy given to the system. It is suggested that the temperature-dependent transition of the electric properties in the nanocomposite is closely associated with the α-relaxation. The large increase in the dissipation factor and electric conductivity depends on the direct current conduction of thermally activated charge carriers resulting from the epoxy matrix above T g.

  7. Temperature dependent kinematic viscosity of different types of engine oils

    Directory of Open Access Journals (Sweden)

    Libor Severa

    2009-01-01

    Full Text Available The objective of this study is to measure how the viscosity of engine oil changes with temperature. Six different commercially distributed engine oils (primarily intended for motorcycle engines of 10W–40 viscosity grade have been evaluated. Four of the oils were of synthetic type, two of semi–synthetic type. All oils have been assumed to be Newtonian fluids, thus flow curves have not been determined. Oils have been cooled to below zero temperatures and under controlled temperature regulation, kinematic viscosity (mm2 / s have been measured in the range of −5 °C and +115 °C. Anton Paar digital viscometer with concentric cylinders geometry has been used. In accordance with expected behavior, kinematic viscosity of all oils was decreasing with increasing temperature. Viscosity was found to be independent on oil’s density. Temperature dependence has been modeled using se­ve­ral mathematical models – Vogel equation, Arrhenius equation, polynomial, and Gaussian equation. The best match between experimental and computed data has been achieved for Gaussian equation (R2 = 0.9993. Knowledge of viscosity behavior of an engine oil as a function of its temperature is of great importance, especially when considering running efficiency and performance of combustion engines. Proposed models can be used for description and prediction of rheological behavior of engine oils.

  8. Study of the temperature dependent nitrogen retention in tungsten surfaces by XPS-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Plank, Ulrike [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Fakultaet fuer Physik der Ludwig-Maximilians-Universitaet Muenchen, Schellingstrasse 4, D-80799 Muenchen (Germany); Meisl, Gerd; Hoeschen, Till [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)

    2016-07-01

    To reduce the power load on the divertor of fusion experiments, nitrogen (N) is puffed into the plasma. As a side effect, nitrogen gets implanted into the tungsten (W) walls of the reactor and forms nitride layers. Their formation and, therefore, the N accumulation in W showed an unexpected temperature dependence in previous experiments. To study the nitrogen retention, we implanted N ions with an energy of 300 eV into W and observed the evolution of the surface composition by X-ray photoelectron spectroscopy (XPS). We find that the N content does not change when the sample is annealed up to 800 K after implantation at lower temperatures. In contrast, the N concentration decreases with increasing implantation temperature. At 800 K implantation temperature, the N saturation level is about 5 times lower compared to 300 K implantation. A possible explanation for this difference is an enhanced diffusion during ion bombardment due to changes in the structure or in the chemical state of the tungsten nitride system. Ongoing tungsten nitride erosion experiments shall help to clarify whether the strong temperature dependence is the result of enhanced diffusion or of phase changes.

  9. The temperature dependence of intermediate range oxygen-oxygen correlations in liquid water

    International Nuclear Information System (INIS)

    Schlesinger, Daniel; Pettersson, Lars G. M.; Wikfeldt, K. Thor; Skinner, Lawrie B.; Benmore, Chris J.; Nilsson, Anders

    2016-01-01

    We analyze the recent temperature dependent oxygen-oxygen pair-distribution functions from experimental high-precision x-ray diffraction data of bulk water by Skinner et al. [J. Chem. Phys. 141, 214507 (2014)] with particular focus on the intermediate range where small, but significant, correlations are found out to 17 Å. The second peak in the pair-distribution function at 4.5 Å is connected to tetrahedral coordination and was shown by Skinner et al. to change behavior with temperature below the temperature of minimum isothermal compressibility. Here we show that this is associated also with a peak growing at 11 Å which strongly indicates a collective character of fluctuations leading to the enhanced compressibility at lower temperatures. We note that the peak at ∼13.2 Å exhibits a temperature dependence similar to that of the density with a maximum close to 277 K or 4 °C. We analyze simulations of the TIP4P/2005 water model in the same manner and find excellent agreement between simulations and experiment albeit with a temperature shift of ∼20 K.

  10. The temperature dependence of intermediate range oxygen-oxygen correlations in liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Schlesinger, Daniel; Pettersson, Lars G. M., E-mail: Lars.Pettersson@fysik.su.se [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Wikfeldt, K. Thor [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Science Institute, University of Iceland, VR-III, 107 Reykjavik (Iceland); Skinner, Lawrie B.; Benmore, Chris J. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Nilsson, Anders [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-08-28

    We analyze the recent temperature dependent oxygen-oxygen pair-distribution functions from experimental high-precision x-ray diffraction data of bulk water by Skinner et al. [J. Chem. Phys. 141, 214507 (2014)] with particular focus on the intermediate range where small, but significant, correlations are found out to 17 Å. The second peak in the pair-distribution function at 4.5 Å is connected to tetrahedral coordination and was shown by Skinner et al. to change behavior with temperature below the temperature of minimum isothermal compressibility. Here we show that this is associated also with a peak growing at 11 Å which strongly indicates a collective character of fluctuations leading to the enhanced compressibility at lower temperatures. We note that the peak at ∼13.2 Å exhibits a temperature dependence similar to that of the density with a maximum close to 277 K or 4 °C. We analyze simulations of the TIP4P/2005 water model in the same manner and find excellent agreement between simulations and experiment albeit with a temperature shift of ∼20 K.

  11. Temperature dependent empirical pseudopotential theory for self-assembled quantum dots.

    Science.gov (United States)

    Wang, Jianping; Gong, Ming; Guo, Guang-Can; He, Lixin

    2012-11-28

    We develop a temperature dependent empirical pseudopotential theory to study the electronic and optical properties of self-assembled quantum dots (QDs) at finite temperature. The theory takes the effects of both lattice expansion and lattice vibration into account. We apply the theory to InAs/GaAs QDs. For the unstrained InAs/GaAs heterostructure, the conduction band offset increases whereas the valence band offset decreases with increasing temperature, and there is a type-I to type-II transition at approximately 135 K. Yet, for InAs/GaAs QDs, the holes are still localized in the QDs even at room temperature, because the large lattice mismatch between InAs and GaAs greatly enhances the valence band offset. The single-particle energy levels in the QDs show a strong temperature dependence due to the change of confinement potentials. Because of the changes of the band offsets, the electron wavefunctions confined in QDs increase by about 1-5%, whereas the hole wavefunctions decrease by about 30-40% when the temperature increases from 0 to 300 K. The calculated recombination energies of excitons, biexcitons and charged excitons show red shifts with increasing temperature which are in excellent agreement with available experimental data.

  12. Similar temperature dependencies of glycolytic enzymes: an evolutionary adaptation to temperature dynamics?

    Directory of Open Access Journals (Sweden)

    Cruz Luisa Ana B

    2012-12-01

    Full Text Available Abstract Background Temperature strongly affects microbial growth, and many microorganisms have to deal with temperature fluctuations in their natural environment. To understand regulation strategies that underlie microbial temperature responses and adaptation, we studied glycolytic pathway kinetics in Saccharomyces cerevisiae during temperature changes. Results Saccharomyces cerevisiae was grown under different temperature regimes and glucose availability conditions. These included glucose-excess batch cultures at different temperatures and glucose-limited chemostat cultures, subjected to fast linear temperature shifts and circadian sinoidal temperature cycles. An observed temperature-independent relation between intracellular levels of glycolytic metabolites and residual glucose concentration for all experimental conditions revealed that it is the substrate availability rather than temperature that determines intracellular metabolite profiles. This observation corresponded with predictions generated in silico with a kinetic model of yeast glycolysis, when the catalytic capacities of all glycolytic enzymes were set to share the same normalized temperature dependency. Conclusions From an evolutionary perspective, such similar temperature dependencies allow cells to adapt more rapidly to temperature changes, because they result in minimal perturbations of intracellular metabolite levels, thus circumventing the need for extensive modification of enzyme levels.

  13. Temperature-dependent optical absorption of SrTiO3

    International Nuclear Information System (INIS)

    Kok, Dirk J.; Irmscher, Klaus; Naumann, Martin; Guguschev, Christo; Galazka, Zbigniew; Uecker, Reinhard

    2015-01-01

    The optical absorption edge and near infrared absorption of SrTiO 3 were measured at temperatures from 4 to 1703 K. The absorption edge decreases from 3.25 eV at 4 K to 1.8 eV at 1703 K and is extrapolated to approximately 1.2 eV at the melting point (2350 K). The transmission in the near IR decreases rapidly above 1400 K because of free carrier absorption and is about 50% of the room temperature value at 1673 K. The free carriers are generated by thermal excitation of electrons over the band gap and the formation of charged vacancies. The observed temperature-dependent infrared absorption can be well reproduced by a calculation based on simple models for the intrinsic free carrier concentration and the free carrier absorption coefficient. The measured red shift of the optical absorption edge and the rising free carrier absorption strongly narrow the spectral range of transmission and impede radiative heat transport through the crystal. These effects have to be considered in high temperature applications of SrTiO 3 -based devices, as the number of free carriers rises considerably, and in bulk crystal growth to avoid growth instabilities. Temperature dependent optical absorption edge of SrTiO 3 , measured, fitted, and extrapolated to the melting point. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Irradiation temperature dependence of production efficiency of lattice defects in some neutron-irradiated oxides

    International Nuclear Information System (INIS)

    Okada, Moritami; Atobe, Kozo; Nakagawa, Masuo

    2004-01-01

    Temperature dependence of production efficiency of irradiation-induced defects in neutron-irradiated oxides has been investigated. Some oxide single crystals, MgO, α-Al 2 O 3 (sapphire) and TiO 2 (rutile), were irradiated at several controlled temperatures, 10, 20, 50, 100, 150 and 200 K, using the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL), and at ambient temperature (∼370 K) in the same facility. Irradiation temperature dependence of production efficiency of a 1 μm band in TiO 2 differs greatly from that of anion vacancy (F-type centers) in MgO and α-Al 2 O 3 . Results for MgO and α-Al 2 O 3 show steep negative gradients from 10 to 370 K, whereas that for TiO 2 includes a valley between 40 and 60 K and a hump at about 130 K, and then disappear at about 200 K. In MgO and α-Al 2 O 3 , this behavior can be explained by the recombination of Frenkel pairs, which is activated at higher temperature. In TiO 2 , in addition to the recombination mechanism, a covalent bonding property is thought to be exerted strong influence, and it is suggested that a disappearance of the 1 μm band at above 200 K is due to the recombination process of Frenkel pairs which is caused by the irradiation-induced crystallization

  15. Temperature dependence of the work function of ruthenium-based gate electrodes

    International Nuclear Information System (INIS)

    Alshareef, H.N.; Wen, H.C.; Luan, H.F.; Choi, K.; Harris, H.R.; Senzaki, Y.; Majhi, P.; Lee, B.H.; Foran, B.; Lian, G.

    2006-01-01

    The effect of device fabrication temperature on the work function of ruthenium (Ru) metal gate and its bilayers was investigated. The work function shows strong temperature dependence when Ru electrodes are deposited on silicon oxide, SiO 2 , but not on hafnium silicates (HfSiO x ). Specifically, the work function of Ru on SiO 2 increased from 4.5 eV at 500 deg. C to 5.0 eV at 700 deg. C. On further annealing to 900 deg. C or higher, the work function dropped to about 4.4 eV. In the case of HfSiO x , the work function of Ru changed by less than 100 mV over the same temperature range. Identical temperature dependence was observed using hafnium (Hf)/Ru and tantalum (Ta)/Ru bilayers. However, the peak values of the work function decreased with increasing Hf/Ru and Ta/Ru thickness ratios. Materials analysis suggests that these trends are driven by interactions at the Ru metal gate-dielectric interface

  16. Effects of a metallic front gate on the temperature-dependent electronic property of pentacene films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yow-Jon, E-mail: rzr2390@yahoo.com.tw [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China); Tsao, Hou-Yen [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China); Liu, Day-Shan [Graduate Institute of Electro-Optical and Materials Science, National Formosa University, Huwei 632, Taiwan (China)

    2014-11-14

    The effect of a metallic front gate on the temperature-dependent electronic property of pentacene films was investigated in this study. The carrier mobility exhibits strong temperature dependence, implying the dominance of tunneling (hopping) at low (high) temperatures. The room-temperature mobility was drastically increased by capping an In (Au) layer on the pentacene front surface. However, the carrier concentration is not affected. An increase in the phonon energy occurs for In-capped or Au-capped pentacene samples, which corresponds to the abrupt transition to the nonlocal electron–phonon coupling. The enhanced mobility by capping a metal layer is attributed to a change in the electron–phonon coupling. - Highlights: • For the metal-capped and uncapped pentacene films, the mobility was researched. • The mobility was dramatically increased by capping an In (Au) layer. • The induced strain by capping a metal layer is found. • The strain may lead to the electron–phonon coupling variation. • The enhanced mobility is attributed to the weakened electron–phonon coupling.

  17. Low-Frequency Loudspeaker-Room Simulation Using Finite Differences in the Time Domain-Part 1: Analysis<strong> strong>

    DEFF Research Database (Denmark)

    Celestinos, Adrian; Nielsen, Sofus Birkedal

    2008-01-01

    Small- and medium-size rectangular rooms have a strong influence on the low-frequency performance of loudspeakers. A simulation program based on the finite-difference time-domain (FDTD) method is introduced to analyze the sound field produced by loudspeakers in rectangular rooms at low frequencies...

  18. Correlation between temperature dependence of elastic moduli and Debye temperature of paramagnetic metal

    International Nuclear Information System (INIS)

    Bodryakov, V.Yu.; Povzner, A.A.

    2000-01-01

    The correlation between the temperature dependence of elastic moduli and the Debye temperature of paramagnetic metal is analyzed in neglect of the temperature dependence of the Poison coefficient σ within the frames of the Debye-Grueneisen presentations. It is shown, that namely the temperature dependence of the elastic moduli determines primarily the temperature dependence of the Debye temperature Θ(T). On the other hand, the temperature dependence Θ(T) very weakly effects the temperature dependence of the elastic moduli. The later made it possible to formulate the self-consistent approach to calculation of the elastic moduli temperature dependence. The numerical estimates of this dependence parameters are conducted by the example of the all around compression modulus of the paramagnetic lutetium [ru

  19. Temperature dependent electrical characteristics of Zn/ZnSe/n-GaAs/In structure

    Science.gov (United States)

    Sağlam, M.; Güzeldir, B.

    2016-04-01

    We have reported a study of the I-V characteristics of Zn/ZnSe/n-GaAs/In sandwich structure in a wide temperature range of 80-300 K by a step of 20 K, which are prepared by Successive Ionic Layer Adsorption and Reaction (SILAR) method. The main electrical parameters, such as ideality factor and zero-bias barrier height determined from the forward bias I-V characteristics were found strongly depend on temperature and when the increased, the n decreased with increasing temperature. The ideality factor and barrier height values as a function of the sample temperature have been attributed to the presence of the lateral inhomogeneities of the barrier height. Furthermore, the series resistance have been calculated from the I-V measurements as a function of temperature dependent.

  20. Temperature dependence of ion-beam induced amorphization in α-quartz

    International Nuclear Information System (INIS)

    Dhar, Sankar; Bolse, Wolfgang; Lieb, Klaus-Peter

    1999-01-01

    The temperature dependence of the amorphization in α-quartz by Ne-ion bombardment has been investigated using Rutherford Backscattering Spectrometry in channeling geometry (RBS-C). The experimental results show that the critical temperature T c for inhibiting amorphization in quartz is around 940 K. The damage depth profile χ(z,phi) is independent of the temperature and fluence and can be simulated with a power-law function [χ(z,phi)∝(phiF D (z)) 3 ] of the damage energy distribution F D (z). At low irradiation temperature, the critical dose phi c for amorphization is independent of the temperature but it strongly increases at higher temperatures with an activation energy of 0.28 eV and has been explained by out-diffusion model of Morehead and Crowder

  1. Solubility Temperature Dependence Predicted from 2D Structure

    Directory of Open Access Journals (Sweden)

    Alex Avdeef

    2015-12-01

    Full Text Available The objective of the study was to find a computational procedure to normalize solubility data determined at various temperatures (e.g., 10 – 50 oC to values at a “reference” temperature (e.g., 25 °C. A simple procedure was devised to predict enthalpies of solution, ΔHsol, from which the temperature dependence of intrinsic (uncharged form solubility, log S0, could be calculated. As dependent variables, values of ΔHsol at 25 °C were subjected to multiple linear regression (MLR analysis, using melting points (mp and Abraham solvation descriptors. Also, the enthalpy data were subjected to random forest regression (RFR and recursive partition tree (RPT analyses. A total of 626 molecules were examined, drawing on 2040 published solubility values measured at various temperatures, along with 77 direct calori    metric measurements. The three different prediction methods (RFR, RPT, MLR all indicated that the estimated standard deviations in the enthalpy data are 11-15 kJ mol-1, which is concordant with the 10 kJ mol-1 propagation error estimated from solubility measurements (assuming 0.05 log S errors, and consistent with the 7 kJ mol-1 average reproducibility in enthalpy values from interlaboratory replicates. According to the MLR model, higher values of mp, H‑bond acidity, polarizability/dipolarity, and dispersion forces relate to more positive (endothermic enthalpy values. However, molecules that are large and have high H-bond basicity are likely to possess negative (exothermic enthalpies of solution. With log S0 values normalized to 25 oC, it was shown that the interlaboratory average standard deviations in solubility measurement are reduced to 0.06 ‑ 0.17 log unit, with higher errors for the least-soluble druglike molecules. Such improvements in data mining are expected to contribute to more reliable in silico prediction models of solubility for use in drug discovery.

  2. Temperature dependence of looping rates in a short peptide.

    Science.gov (United States)

    Roccatano, Danilo; Sahoo, Harekrushna; Zacharias, Martin; Nau, Werner M

    2007-03-15

    Knowledge of the influence of chain length and amino acid sequence on the structural and dynamic properties of small peptides in solution provides essential information on protein folding pathways. The combination of time-resolved optical spectroscopy and molecular dynamics (MD) simulation methods has become a powerful tool to investigate the kinetics of end-to-end collisions (looping rates) in short peptides, which are relevant in early protein folding events. We applied the combination of both techniques to study temperature-dependent (280-340 K) looping rates of the Dbo-AlaGlyGln-Trp-NH2 peptide, where Dbo represents a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine, which served as a fluorescent probe in the time-resolved spectroscopic experiments. The experimental looping rates increased from 4.8 x 10(7) s(-1) at 283 K to 2.0 x 10(8) s(-1) at 338 K in H2O. The corresponding Arrhenius plot provided as activation parameters Ea = 21.5 +/- 1.0 kJ mol(-1) and ln(A/s-1) = 26.8 +/- 0.2 in H2O. The results in D2O were consistent with a slight solvent viscosity effect, i.e., the looping rates were 10-20% slower. MD simulations were performed with the GROMOS96 force field in a water solvent model, which required first a parametrization of the synthetic amino acid Dbo. After corrections for solvent viscosity effects, the calculated looping rates varied from 1.5 x 10(8) s(-1) at 280 K to 8.2 x 10(8) s(-1) at 340 K in H2O, which was about four times larger than the experimental data. The calculated activation parameters were Ea = 24.7 +/- 1.5 kJ mol(-1) and ln(A/s(-1)) = 29.4 +/- 0.1 in H2O.

  3. Bending behavior of thermoplastic composite sheets viscoelasticity and temperature dependency in the draping process

    CERN Document Server

    Ropers, Steffen

    2017-01-01

    Within the scope of this work, Steffen Ropers evaluates the viscoelastic and temperature-dependent nature of the bending behavior of thermoplastic composite sheets in order to further enhance the predictability of the draping simulation. This simulation is a useful tool for the development of robust large scale processes for continuously fiber-reinforced polymers (CFRP). The bending behavior thereby largely influences the size and position of wrinkles, which are one of the most common processing defects for continuously fiber-reinforced parts. Thus, a better understanding of the bending behavior of thermoplastic composite sheets as well as an appropriate testing method along with corresponding material models contribute to a wide-spread application of CFRPs in large scale production. Contents Thermoplastic Prepregs Draping Simulation of Thermoplastic Prepregs Bending Characterization of Textile Composites Modeling of Bending Behavior Target Groups Researchers and students in the field of polymer, lightweight,...

  4. Temperature dependent optical properties of (002) oriented ZnO thin film using surface plasmon resonance

    Science.gov (United States)

    Saha, Shibu; Mehan, Navina; Sreenivas, K.; Gupta, Vinay

    2009-08-01

    Temperature dependent optical properties of c-axis oriented ZnO thin film were investigated using surface plasmon resonance (SPR) technique. SPR data for double layer (prism-Au-ZnO-air) and single layer (prism-Au-air) systems were taken over a temperature range (300-525 K). Dielectric constant at optical frequency and real part of refractive index of the ZnO film shows an increase with temperature. The bandgap of the oriented ZnO film was found to decrease with rise in temperature. The work indicates a promising application of the system as a temperature sensor and highlights an efficient scientific tool to study optical properties of thin film under varying ambient conditions.

  5. Temperature dependent transport characteristics of graphene/n-Si diodes

    NARCIS (Netherlands)

    Parui, S.; Ruiter, R.; Zomer, P. J.; Wojtaszek, M.; van Wees, B. J.; Banerjee, T.

    2014-01-01

    Realizing an optimal Schottky interface of graphene on Si is challenging, as the electrical transport strongly depends on the graphene quality and the fabrication processes. Such interfaces are of increasing research interest for integration in diverse electronic devices as they are thermally and

  6. Temperature Dependent Charge Carrier Dynamics in Formamidinium Lead Iodide Perovskite

    NARCIS (Netherlands)

    Gelvez Rueda, M.C.; Renaud, N.; Grozema, F.C.

    2017-01-01

    The fundamental opto-electronic properties of organic-inorganic hybrid perovskites are strongly affected by their structural parameters. These parameters are particularly critical in formamidinium lead iodide (FAPbI3), in which its large structural disorder leads to a non-perovskite

  7. Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.

    Science.gov (United States)

    Weber, Sam B; Blount, Jonathan D; Godley, Brendan J; Witt, Matthew J; Broderick, Annette C

    2011-09-01

    1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic

  8. Transient and temperature-dependent phenomena in Ge:Be and Ge:Zn far infrared photoconductors

    International Nuclear Information System (INIS)

    Haegel, N.M.

    1985-11-01

    An experimental study of the transient and temperature-dependent behavior of Ge:Be and Ge:Zn photoconductors has been performed under the low background photon flux conditions (p dot approx. = 10 8 photons/second) typical of astronomy and astrophysics applications. The responsivity of Ge:Be and Ge:Zn detectors is strongly temperature-dependent in closely compensated material, and the effect of compensation on free carrier lifetime in Ge:Be has been measured using the photo-Hall effect technique. Closely compensated material has been obtained by controlling the concentration of novel hydrogen-related shallow acceptor complexes, A(Be,H) and A(Zn,H), which exist in doped crystals grown under a H 2 atmosphere. A review of selection criteria for multilevel materials for optimum photoconductor performance is included. 55 refs., 47 figs

  9. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Akhilesh Kumar [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Hsu, Jen-Hwa [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2016-11-15

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)]{sub 2}/FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (T{sub A}=200, 300 and 400 °C). Structural analyzes reveal that the films annealed at T{sub A}≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at T{sub A}=300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M–H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), T{sub A} and temperature. A large reduction in coercivity (H{sub C}) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of H{sub C}(T), i.e., a broad minimum in H{sub C}(T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the H{sub C}(T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (T{sub C}) with T{sub A} (x). The multilayer films annealed at 200 °C exhibit low value of T{sub C} with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest T{sub C} with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and

  10. A Novel Candidate Gene for Temperature-Dependent Sex Determination in the Common Snapping Turtle

    Science.gov (United States)

    Schroeder, Anthony L.; Metzger, Kelsey J.; Miller, Alexandra; Rhen, Turk

    2016-01-01

    Temperature-dependent sex determination (TSD) was described nearly 50 years ago. Researchers have since identified many genes that display differential expression at male- vs. female-producing temperatures. Yet, it is unclear whether these genes (1) are involved in sex determination per se, (2) are downstream effectors involved in differentiation of ovaries and testes, or (3) are thermo-sensitive but unrelated to gonad development. Here we present multiple lines of evidence linking CIRBP to sex determination in the snapping turtle, Chelydra serpentina. We demonstrate significant associations between a single nucleotide polymorphism (SNP) (c63A > C) in CIRBP, transcript levels in embryonic gonads during specification of gonad fate, and sex in hatchlings from a thermal regime that produces mixed sex ratios. The A allele was induced in embryos exposed to a female-producing temperature, while expression of the C allele did not differ between female- and male-producing temperatures. In accord with this pattern of temperature-dependent, allele-specific expression, AA homozygotes were more likely to develop ovaries than AC heterozygotes, which, in turn, were more likely to develop ovaries than CC homozygotes. Multiple regression using SNPs in CIRBP and adjacent loci suggests that c63A > C may be the causal variant or closely linked to it. Differences in CIRBP allele frequencies among turtles from northern Minnesota, southern Minnesota, and Texas reflect small and large-scale latitudinal differences in TSD pattern. Finally, analysis of CIRBP protein localization reveals that CIRBP is in a position to mediate temperature effects on the developing gonads. Together, these studies strongly suggest that CIRBP is involved in determining the fate of the bipotential gonad. PMID:26936926

  11. Irradiation temperature dependence of production efficiency of lattice defects in some neutron-irradiated oxides

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Moritami [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 5900494 (Japan)]. E-mail: okada@rri.kyoto-u.ac.jp; Atobe, Kozo [Faculty of Science, Naruto University of Education, Naruto, Tokushima 7728502 (Japan); Nakagawa, Masuo [Faculty of Education, Kagawa University, Takamatsu, Kagawa 7608522 (Japan)

    2004-11-01

    Temperature dependence of production efficiency of irradiation-induced defects in neutron-irradiated oxides has been investigated. Some oxide single crystals, MgO, {alpha}-Al{sub 2}O{sub 3} (sapphire) and TiO{sub 2} (rutile), were irradiated at several controlled temperatures, 10, 20, 50, 100, 150 and 200 K, using the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL), and at ambient temperature ({approx}370 K) in the same facility. Irradiation temperature dependence of production efficiency of a 1 {mu}m band in TiO{sub 2} differs greatly from that of anion vacancy (F-type centers) in MgO and {alpha}-Al{sub 2}O{sub 3}. Results for MgO and {alpha}-Al{sub 2}O{sub 3} show steep negative gradients from 10 to 370 K, whereas that for TiO{sub 2} includes a valley between 40 and 60 K and a hump at about 130 K, and then disappear at about 200 K. In MgO and {alpha}-Al{sub 2}O{sub 3}, this behavior can be explained by the recombination of Frenkel pairs, which is activated at higher temperature. In TiO{sub 2}, in addition to the recombination mechanism, a covalent bonding property is thought to be exerted strong influence, and it is suggested that a disappearance of the 1 {mu}m band at above 200 K is due to the recombination process of Frenkel pairs which is caused by the irradiation-induced crystallization.

  12. Temperature dependent pinning landscapes in REBCO thin films

    Science.gov (United States)

    Jaroszynski, Jan; Constantinescu, Anca-Monia; Hu, Xinbo Paul

    2015-03-01

    The pinning landscapes of REBCO (RE=rare earth elements) thin films have been a topic of study in recent years due to, among other reasons, their high ability to introduce various phases and defects. Pinning mechanisms studies in high temperature superconductors often require detailed knowledge of critical current density as a function of magnetic field orientation as well as field strength and temperature. Since the films can achieve remarkably high critical current, challenges exist in evaluating these low temperature (down to 4.2 K) properties in high magnetic fields up to 30 T. Therefore both conventional transport, and magnetization measurements in a vibrating coil magnetometer equipped with rotating sample platform were used to complement the study. Our results clearly show an evolution of pinning from strongly correlated effects seen at high temperatures to significant contributions from dense but weak pins that thermal fluctuations render ineffective at high temperatures but which become strong at lower temperatures Support for this work is provided by the NHMFL via NSF DRM 1157490

  13. Temperature dependent optical properties of ZnO thin film using ellipsometry and photoluminescence

    Science.gov (United States)

    Bouzourâa, M.-B.; Battie, Y.; Dalmasso, S.; Zaïbi, M.-A.; Oueslati, M.; En Naciri, A.

    2018-05-01

    We report the temperature dependence of the dielectric function, the exciton binding energy and the electronic transitions of crystallized ZnO thin film using spectroscopic ellipsometry (SE) and photoluminescence (PL). ZnO layers were prepared by sol-gel method and deposited on crystalline silicon (Si) by spin coating technique. The ZnO optical properties were determined between 300 K and 620 K. Rigorous study of optical responses was achieved in order to demonstrate the quenching exciton of ZnO as a function of temperature. Numerical technique named constrained cubic splines approximation (CCS), Tauc-Lorentz (TL) and Tanguy dispersion models were selected for the ellipsometry data modeling in order to obtain the dielectric function of ZnO. The results reveals that the exciton bound becomes widely flattening at 470 K on the one hand, and on the other that the Tanguy dispersion law is more appropriate for determining the optical responses of ZnO thin film in the temperature range of 300 K-420 K. The Tauc-Lorentz, for its part, reproduces correctly the ZnO dielectric function in 470 K-620 K temperature range. The temperature dependence of the electronic transition given by SE and PL shows that the exciton quenching was observed in 420 K-∼520 K temperature range. This quenching effect can be explained by the equilibrium between the Coulomb force of exciton and its kinetic energy in the film. The kinetic energy was found to induce three degrees of freedom of the exciton.

  14. Microstructural effects on the yield strength and its temperature dependence in a bainitic precipitation hardened Cr-Mo-V steel

    International Nuclear Information System (INIS)

    Toerroenen, K.; Kotilainen, H.; Nenonen, P.

    1980-03-01

    The plastic deformation behaviour of a precipitation hardened bainitic Cr-Mo-V steel is analyzed at ambient and low temperatures. The temperature dependent component of the yield strength is composed of the Peierls-Nabarro force and also partly of the strengthening contribution of the lath- and cell boundaries or the solid solution hardening. The temperature dependence below 230 K is in accordance with the models presented by Yanoshevich and Ryvkina as well as Dorn and Rajnak. The temperature independent component can be calculated merely from the dislocation density, which is stabilized by the vanadium-rich carbides. The linear additivity cannot be used for the superposition of the strengthening effects of various strengthening parameters, By using the phenomenological approach starting from the dislocation movement mechanisms upon yielding the laws for the superposition are discussed. (author)

  15. Temperature dependence of electronic transport property in ferroelectric polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.L.; Wang, J.L., E-mail: jlwang@mail.sitp.ac.cn; Tian, B.B.; Liu, B.L.; Zou, Y.H.; Wang, X.D.; Sun, S.; Sun, J.L., E-mail: jlsun@mail.sitp.ac.cn; Meng, X.J.; Chu, J.H.

    2014-10-15

    Highlights: • The ferroelectric polymer was fabricated by Langmuir–Blodgett method. • The electrons as the dominant injected carrier were conformed in the ferroelectric polymer films. • The leakage current conduction mechanisms in ferroelectric polymer were investigated. - Abstract: The leakage current mechanism of ferroelectric copolymer of polyvinylidene fluoride with trifluoroethylene prepared by Langmuir–Blodgett was investigated in the temperature range from 100 K to 350 K. The electron as the dominant injected carrier was observed in the ferroelectric copolymer films. The transport mechanisms in copolymer strongly depend on the temperature and applied voltage. From 100 K to 200 K, Schottky emission dominates the conduction. With temperature increasing, the Frenkel–Poole emission instead of the Schottky emission to conduct the carrier transport. When the temperature gets to 260 K, the leakage current becomes independent of temperature, and the space charge limited current conduction was observed.

  16. Frequency and temperature dependent dielectric properties of TiO2-V2O5 nanocomposites

    Science.gov (United States)

    Ray, Apurba; Roy, Atanu; De, Sayan; Chatterjee, Souvik; Das, Sachindranath

    2018-03-01

    In this manuscript, we have reported the crystal structure, dielectric response, and transport phenomenon of TiO2-V2O5 nanocomposites. The nanocomposites were synthesized using a sol-gel technique having different molar ratios of Ti:V (10:10, 10:15, and 10:20). The phase composition and the morphology have been studied using X-ray diffraction and field emission scanning electron microscope, respectively. The impedance spectroscopy studies of the three samples over a wide range of temperature (50 K-300 K) have been extensively described using the internal barrier layer capacitor model. It is based on the contribution of domain and domain boundary, relaxations of the materials, which are the main crucial factors for the enhancement of the dielectric response. The frequency dependent ac conductivity of the ceramics strongly obeys the well-known Jonscher's power law, and it has been clearly explained using the theory of jump relaxation model. The temperature dependent bulk conductivity is fairly recognized to the variable-range hopping of localized polarons. The co-existence of mixed valence state of Ti ions (Ti3+ and Ti4+) in the sample significantly contributes to the change of dielectric property. The overall study of dielectric response explains that the dielectric constant and the dielectric loss are strongly dependent on temperature and frequency and decrease with an increase of frequency as well as temperature.

  17. Inclusion of temperature dependence of fission barriers in statistical model calculations

    International Nuclear Information System (INIS)

    Newton, J.O.; Popescu, D.G.; Leigh, J.R.

    1990-08-01

    The temperature dependence of fission barriers has been interpolated from the results of recent theoretical calculations and included in the statistical model code PACE2. It is shown that the inclusion of temperature dependence causes significant changes to the values of the statistical model parameters deduced from fits to experimental data. 21 refs., 2 figs

  18. Temperature dependence of positron trapping by vacancies, loops and voids in molybdenum

    International Nuclear Information System (INIS)

    Bentzon, M.D.; Linderoth, S.; Petersen, K.

    1985-01-01

    The temperature dependence of positron trapping by defects in molybdenum has been studied. By resolving positron lifetime spectra into three components, it has been possible to distinguish the temperature dependence of positron trapping into loops and voids. The results show that the positron trapping rate into voids depends linearly on temperature. The temperature dependence of positron trapping by loops can be interpreted as positrons being trapped by jogs, directly or via the dislocation line. The temperature dependence of positrons trapped by loops is argued mainly to be due to the trapping at the dislocation line, and not to detrapping. The observed temperature dependence of positron annihilation parameters in an electron irradiated sample (below stage III), is explained by competitive positron trapping in interstitial loops at low temperatures

  19. Temperature dependence of erythrocyte aggregation in vitro by backscattering nephelometry

    Science.gov (United States)

    Sirko, Igor V.; Firsov, Nikolai N.; Ryaboshapka, Olga M.; Priezzhev, Alexander V.

    1997-05-01

    We apply backscattering nephelometry technique to register the alterations of the scattering signal from a whole blood sample due to appearance or disappearance of different types of erythrocyte aggregates in stasis and under controlled shear stress. The measured parameters are: the characteristic times of linear and 3D aggregates formation, and the strength of aggregates of different types. These parameters depend on the sample temperature in the range of 2 divided by 50 degrees C. Temporal parameters of the aggregation process strongly increase at temperature 45 degrees C. For samples of normal blood the aggregates strength parameters do not significantly depend on the sample temperature, whereas for blood samples from patients suffering Sjogren syndrome we observe high increase of the strength of 3D and linear aggregates and decrease of time of linear aggregates formation at low temperature of the sample. This combination of parameters is opposite to that observed in the samples of pathological blood at room temperature. Possible reasons of this behavior of aggregation state of blood and explanation of the observed effects will be discussed.

  20. Temperature dependence on sodium-water chemical reaction

    International Nuclear Information System (INIS)

    Tamura, Kenta; Deguchi, Yoshihiro; Suzuki, Koichi; Takata, Takashi; Yamaguchi, Akira; Kikuchi, Shin; Ohshima, Hiroyuki

    2012-01-01

    In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes. This process ends up damages on the heat transport equipment in the SFR. Therefore, the study on sodium-water chemical reactions is of paramount importance for security reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. A quasi one-dimensional flame model is also applied to a sodium-water counter-flow reaction field. Temperature, H 2 , H 2 O, OH, Na and Particulate matter were measured using laser induced fluorescence and CARS in the counter-flow reaction field. The temperature of the reaction field was also modified to reduce the condensation of Na in the reaction zone. (author)

  1. Temperature dependent elasticity and damping in dehydrated sandstone

    Science.gov (United States)

    Darling, T. W.; Struble, W.

    2013-12-01

    Work reported previously at this conference, outlining our observation of anomalously large elastic softening and damping in dehydrated Berea sandstone at elevated temperatures, has been analysed to study shear and compressional effects separately. Modeling of the sample using COMSOL software was necessary to identify modes, as the vibration spectrum of the sample is poorly approximated by a uniform isotropic solid. The first torsional mode of our evacuated, dry, core softens at nearly twice the rate of Young's modulus modes (bending and compressional) and is also damped nearly twice as strongly as temperature increases. We consider two possible models for explaining this behavior, based on the assumption that the mechanical properties of the sandstone are dominated by the framework of quartz grains and polycrystalline cementation, neglecting initially the effects of clay and feldspar inclusions. The 20cm x 2.54cm diameter core is dry such that the pressure of water vapor in the experiment chamber is below 1e-6 Torr at 70C, suggesting that surface water beyond a small number of monolayers is negligible. Our models consider (1) enhanced sliding of grain boundaries in the cementation at elevated temperature and reduced internal water content, and (2) strain microcracking of the cementatioin at low water content due to anisotropic expansion in the quartz grains. In model (1) interfaces parallel to polyhedral grain surfaces were placed in the cement bonds and assigned frictional properties. Model (2) has not yet been implemented. The overall elasticity of a 3-D several-grain model network was determined by modeling quasistatic loading and measuring displacements. Initial results with a small number of grains/bonds suggests that only the first model provides softening and damping for all the modes, however the details of the effects of defect motioin at individual interfaces as the source for the frictional properties is still being evaluated. Nonlinear effects are

  2. Temperature Dependence of Mineral Solubility in Water. Part 2. Alkaline and Alkaline Earth Bromides

    Science.gov (United States)

    Krumgalz, B. S.

    2018-03-01

    Databases of alkaline and alkaline earth bromide solubilities in water at various temperatures were created using experimental data from publications over about the last two centuries. Statistical critical evaluation of the created databases was produced since there were enough independent data sources to justify such evaluation. The reliable experimental data were adequately described by polynomial expressions over various temperature ranges. Using the Pitzer approach for ionic activity and osmotic coefficients, the thermodynamic solubility products for the discussed bromide minerals have been calculated at various temperature intervals and also represented by polynomial expressions.

  3. Temperature-dependence of stress and elasticity in wet-transferred graphene membranes

    Science.gov (United States)

    De Alba, Roberto; Abhilash, T. S.; Hui, Aaron; Storch, Isaac R.; Craighead, Harold G.; Parpia, Jeevak M.

    2018-03-01

    We report measurements of the mechanical properties of two suspended graphene membranes in the temperature range of 80 K to 550 K. For this entire range, the resonant frequency and quality factor of each device were monitored continuously during cooling and heating. Below 300 K, we have additionally measured the resonant frequency's tunability via electrostatic force, and modeled this data to determine graphene's tension and elastic modulus; both of these parameters are found to be strongly temperature-dependent in this range. Above 300 K, we observe a resonant frequency (and therefore tension) minimum near room temperature. This suggests that the thermal expansion coefficient is positive for temperatures below roughly 315 K, and negative for higher temperatures. Lastly, we observe a large, reproducible hysteresis in the resonant frequency as our graphene devices are cycled between 300 K and 550 K. After returning to 300 K, the measured frequency evolves exponentially in time with a time constant of ˜24 h. Our results clash with expectations for pristine graphene membranes, but are consistent with expectations for composite membranes composed of graphene coated by a thin layer of polymer residue.

  4. Experimental determination of the temperature-dependent penetration depth in V3Si

    International Nuclear Information System (INIS)

    Christen, D.K.; Kerchner, H.R.; Sekula, S.T.; Chang, Y.K.

    1984-03-01

    Small angle neutron diffraction from the flux-line lattice (FLL) in a high quality, single crystal of superconducting V 3 Si has been used to deduce the low-field penetration depth lambda (T). An absolute determination is possible because the FLL form factor F/sub hk/ is essentially single-valued in the scattering vector magnitude absolute value of K/sub hk/, as well as nearly London-like at low field. We obtain lambda (0) = 102 +- 1 nm, 20% to 30% larger than previous determinations of the London penetration depth lambda/sub L/ (0). The temperature dependence of lambda (T) is found to deviate from that of the BCS theory. An assessment of the data indicates the most prominent source of the discrepancy is due to strong electron-phonon coupling, and we find 2Δ(0)/k/sub B/T/sub c/ = 3.88 +- 0.07, in reasonable agreement with values found in the literature

  5. Plasmon resonance enhanced temperature-dependent photoluminescence of Si-V centers in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shaoheng [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Song, Jie; Wang, Qiliang; Liu, Junsong; Li, Hongdong, E-mail: hdli@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Zhang, Baolin [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2015-11-23

    Temperature dependent optical property of diamond has been considered as a very important factor for realizing high performance diamond-based optoelectronic devices. The photoluminescence feature of the zero phonon line of silicon-vacancy (Si-V) centers in Si-doped chemical vapor deposited single crystal diamond (SCD) with localized surface plasmon resonance (LSPR) induced by gold nanoparticles has been studied at temperatures ranging from liquid nitrogen temperature to 473 K, as compared with that of the SCD counterpart in absence of the LSPR. It is found that with LSPR the emission intensities of Si-V centers are significantly enhanced by factors of tens and the magnitudes of the redshift (width) of the emissions become smaller (narrower), in comparison with those of normal emissions without plasmon resonance. More interestingly, these strong Si-V emissions appear remarkably at temperatures up to 473 K, while the spectral feature was not reported in previous studies on the intrinsic Si-doped diamonds when temperatures are higher than room temperature. These findings would lead to reaching high performance diamond-based devices, such as single photon emitter, quantum cryptography, biomarker, and so forth, working under high temperature conditions.

  6. Temperature dependence of three-point correlation functions of viscous liquids: the case of glycerol

    Energy Technology Data Exchange (ETDEWEB)

    Dalle-Ferrier, Cecile; Eibl, Stefan; Alba-Simionesco, Christiane [Laboratoire de Chimie Physique, UMR 8000, Batiment 349, Universite Paris-Sud, 91405 Orsay (France); Pappas, Catherine [BENSC, Hahn-Meitner-Institute, HMI Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany)], E-mail: cecile.dalle-ferrier@lcp.u-psud.fr

    2008-12-10

    What causes the dramatic slowing down of flow and relaxation that leads to glass formation in liquids as temperature decreases is hardly understood so far and is the subject of intensive research work. It is tempting to ascribe the strong temperature dependence of the dynamics, irrespective of molecular details, to a collective or cooperative behavior characterized by a length scale that grows as one approaches the glass transition. To access this length experimentally, we use the recently introduced three-point dynamic susceptibility, from which the number of molecules dynamically correlated during the structural relaxation, N{sub corr}, can be extracted. The three-point functions are related to the sensitivity of the averaged two-time dynamics to external control parameters, such as temperature and density. We studied N{sub corr} values in an important temperature range for a large number of liquids, and found that it systematically grows when approaching the glass transition. Here we specially emphasize the case of glycerol for which we combined dielectric and neutron spin echo spectroscopy to cover more than 16 decades in relaxation time.

  7. Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

    Science.gov (United States)

    Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

    2017-10-25

    Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

  8. Temperature dependence of the interfacial magnetic anisotropy in W/CoFeB/MgO

    Directory of Open Access Journals (Sweden)

    Kyoung-Min Lee

    2017-06-01

    Full Text Available The interfacial perpendicular magnetic anisotropy in W/CoFeB (1.2 ∼ 3 nm/MgO thin film structures is strongly dependent on temperature, and is significantly reduced at high temperature. The interfacial magnetic anisotropy is generally proportional to the third power of magnetization, but an additional factor due to thermal expansion is required to explain the temperature dependence of the magnetic anisotropy of ultrathin CoFeB films. The reduction of the magnetic anisotropy is more prominent for the thinner films; as the temperature increases from 300 K to 400 K, the anisotropy is reduced ∼50% for the 1.2-nm-thick CoFeB, whereas the anisotropy is reduced ∼30% for the 1.7-nm-thick CoFeB. Such a substantial reduction of magnetic anisotropy at high temperature is problematic for data retention when incorporating W/CoFeB/MgO thin film structures into magneto-resistive random access memory devices. Alternative magnetic materials and structures are required to maintain large magnetic anisotropy at elevated temperatures.

  9. Temperature dependence of filament-coupling in Bi-2223 tapes: magneto-optical study

    International Nuclear Information System (INIS)

    Bobyl, A.V.; Shantsev, D.V.; Galperin, Y.M.; Johansen, T.H.; Baziljevich, M.; Gaevski, M.E.

    2000-01-01

    Coupling through random superconducting bridges between filaments in a multifilamentary Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ tape has been investigated by magneto-optical imaging at temperatures from 20 K up to T c . Magnetic flux distributions have been measured on the surface of an intact tape in the remanent state on applying a strong perpendicular magnetic field. The flux distributions observed at low temperatures reflect the arrangement of individual filaments. At high temperatures, the distribution becomes more similar to that for a uniform monocore tape, indicating that superconducting connections appear between the filaments. To discuss the relative contributions of the intra- and inter-filament currents, a simple model based on the Bean critical state was proposed and applied to analyse the temperature dependent behaviour. The inter-filament coupling, increasing with temperature, reaches at 77 K a point where the currents flowing in large inter-filament loops are roughly equal to the intra-filament currents. (author)

  10. Temperature dependence of shear viscosity of SU(3)-gluodynamics within lattice simulation

    Energy Technology Data Exchange (ETDEWEB)

    Astrakhantsev, N.Yu. [Institute for Theoretical and Experimental Physics,25 B. Cheremushkinskaya St., 117218, Moscow (Russian Federation); Moscow Institute of Physics and Technology,9 Institutskii per., 141700, Dolgoprudny (Russian Federation); Braguta, V.V. [Institute for Theoretical and Experimental Physics,25 B. Cheremushkinskaya St., 117218, Moscow (Russian Federation); Institute for High Energy Physics NRC “Kurchatov Institute”,1 Pobedy St., Protvino, 142281 (Russian Federation); School of Biomedicine, Far Eastern Federal University,8 Sukhanova St., 690950, Vladivostok (Russian Federation); Kotov, A.Yu. [Institute for Theoretical and Experimental Physics,25 B. Cheremushkinskaya St., 117218, Moscow (Russian Federation)

    2017-04-18

    In this paper we study the SU(3)-gluodynamics shear viscosity temperature dependence on the lattice. To do so, we measure the correlation functions of the energy-momentum tensor in the range of temperatures T/T{sub c}∈[0.9,1.5]. To extract the shear viscosity we used two approaches. The first one is to fit the lattice data with a physically motivated ansatz for the spectral function with unknown parameters and then determine the shear viscosity. The second approach is to apply the Backus-Gilbert method allowing to extract the shear viscosity from the lattice data nonparametrically. The results obtained within both approaches agree with each other. Our results allow us to conclude that within the range T/T{sub c}∈[0.9,1.5] the SU(3)-gluodynamics reveals the properties of a strongly interacting system, which cannot be described perturbatively, and has the ratio η/s close to the value 1/4π of the N=4 Supersymmetric Yang-Mills theory.

  11. Temperature dependent magnetic properties of the GaAs substrate of spin-LEDs

    International Nuclear Information System (INIS)

    Ney, A; Harris, J S Jr; Parkin, S S P

    2006-01-01

    The temperature dependence of the magnetization of a light emitting diode having a ferromagnetic contact (spin-LED) is measured from 2 to 300 K in magnetic fields from 30 to 70 kOe and it is found that it originates from the GaAs substrate. The magnetization of GaAs comprises a van Vleck-type paramagnetic contribution to the susceptibility which scales inversely with the band gap of the semiconductor. Thus, the temperature dependence of the band gap of GaAs accounts for the non-linear temperature dependent magnetic susceptibility of GaAs and thus, at large magnetic fields, for the spin-LED

  12. Temperature-dependent gate-swing hysteresis of pentacene thin film transistors

    Directory of Open Access Journals (Sweden)

    Yow-Jon Lin

    2014-10-01

    Full Text Available The temperature-dependent hysteresis-type transfer characteristics of pentacene-based organic thin film transistors (OTFTs were researched. The temperature-dependent transfer characteristics exhibit hopping conduction behavior. The fitting data for the temperature-dependent off-to-on and on-to-off transfer characteristics of OTFTs demonstrate that the hopping distance (ah and the barrier height for hopping (qϕt control the carrier flow, resulting in the hysteresis-type transfer characteristics of OTFTs. The hopping model gives an explanation of the gate-swing hysteresis and the roles played by qϕt and ah.

  13. Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures

    International Nuclear Information System (INIS)

    Wu, Z.; Bei, H.; Pharr, G.M.; George, E.P.

    2014-01-01

    Compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. To clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic binary, ternary and quaternary alloys based on the elements Fe, Ni, Co, Cr and Mn that were previously shown to be single-phase face-centered cubic (fcc) solid solutions. The alloys were arc-melted, drop-cast, homogenized, cold-rolled and recrystallized to produce equiaxed microstructures with comparable grain sizes. Tensile tests were performed at an engineering strain rate of 10 −3 s −1 at temperatures in the range 77–673 K. Unalloyed fcc Ni was processed similarly and tested for comparison. The flow stresses depend to varying degrees on temperature, with some (e.g. NiCoCr, NiCoCrMn and FeNiCoCr) exhibiting yield and ultimate strengths that increase strongly with decreasing temperature, while others (e.g. NiCo and Ni) exhibit very weak temperature dependencies. To better understand this behavior, the temperature dependencies of the yield strength and strain hardening were analyzed separately. Lattice friction appears to be the predominant component of the temperature-dependent yield stress, possibly because the Peierls barrier height decreases with increasing temperature due to a thermally induced increase of dislocation width. In the early stages of plastic flow (5–13% strain, depending on material), the temperature dependence of strain hardening is due

  14. Temperature dependency of external stress corrosion crack propagation of 304 stainless steel

    International Nuclear Information System (INIS)

    Hayashibara, Hitoshi; Mizutani, Yoshihiro; Mayuzumi, Masami; Tani, Jun-ichi

    2010-01-01

    Temperature dependency of external stress corrosion cracking (ESCC) of 304 stainless steel was examined with CT specimens. Maximum ESCC propagation rates appeared in the early phase of ESCC propagation. ESCC propagation rates generally became smaller as testing time advance. Temperature dependency of maximum ESCC propagation rate was analyzed with Arrhenius plot, and apparent activation energy was similar to that of SCC in chloride solutions. Temperature dependency of macroscopic ESCC incubation time was different from that of ESCC propagation rate. Anodic current density of 304 stainless steel was also examined by anodic polarization measurement. Temperature dependency of critical current density of active state in artificial sea water solution of pH=1.3 was similar to that of ESCC propagation rate. (author)

  15. Measurement of Linear Coefficient of Thermal Expansion and Temperature-Dependent Refractive Index Using Interferometric System

    Science.gov (United States)

    Corsetti, James A.; Green, William E.; Ellis, Jonathan D.; Schmidt, Greg R.; Moore, Duncan T.

    2017-01-01

    A system combining an interferometer with an environmental chamber for measuring both coefficient of thermal expansion (CTE) and temperature-dependent refractive index (dn/dT) simultaneously is presented. The operation and measurement results of this instrument are discussed.

  16. Bistable impurity centers in silicon. Temperature dependent characteristics of electro- and thermophysical parameters

    Energy Technology Data Exchange (ETDEWEB)

    Musaeva, L F; Igamberdiev, Kh T; Mamadalimov, A T; Khabibullaev, P K [AS RU, Heat Physics Department, Tashkent (Uzbekistan)

    2003-09-01

    On the basis of experimental data covering temperature dependencies of photoelectric and thermodynamic properties of silicon containing defects the possible physical mechanisms of defect center transformation in the silicon lattice and of phase transitions are discussed. (author)

  17. Bistable impurity centers in silicon. Temperature dependent characteristics of electro- and thermophysical parameters

    International Nuclear Information System (INIS)

    Musaeva, L.F.; Igamberdiev, Kh.T.; Mamadalimov, A.T.; Khabibullaev, P.K.

    2003-01-01

    On the basis of experimental data covering temperature dependencies of photoelectric and thermodynamic properties of silicon containing defects the possible physical mechanisms of defect center transformation in the silicon lattice and of phase transitions are discussed. (author)

  18. Accelerated life testing and temperature dependence of device characteristics in GaAs CHFET devices

    Science.gov (United States)

    Gallegos, M.; Leon, R.; Vu, D. T.; Okuno, J.; Johnson, A. S.

    2002-01-01

    Accelerated life testing of GaAs complementary heterojunction field effect transistors (CHFET) was carried out. Temperature dependence of single and synchronous rectifier CHFET device characteristics were also obtained.

  19. Microarray study of temperature-dependent sensitivity and selectivity of metal/oxide sensing interfaces

    Science.gov (United States)

    Tiffany, Jason; Cavicchi, Richard E.; Semancik, Stephen

    2001-02-01

    Conductometric gas microsensors offer the benefits of ppm-level sensitivity, real-time data, simple interfacing to electronics hardware, and low power consumption. The type of device we have been exploring consists of a sensor film deposited on a "microhotplate"- a 100 micron platform with built-in heating (to activate reactions on the sensing surface) and thermometry. We have been using combinatorial studies of 36-element arrays to characterize the relationship between sensor film composition, operating temperature, and response, as measured by the device's sensitivity and selectivity. Gases that have been tested on these arrays include methanol, ethanol, dichloromethane, propane, methane, acetone, benzene, hydrogen, and carbon monoxide, and are of interest in the management of environmental waste sites. These experiments compare tin oxide films modified by catalyst overlayers, and ultrathin metal seed layers. The seed layers are used as part of a chemical vapor deposition process that uses each array element's microheater to activate the deposition of SnO2, and control its microstructure. Low coverage (20 Ê) catalytic metals (Pd, Cu, Cr, In, Au) are deposited on the oxides by masked evaporation or sputtering. This presentation demonstrates the value of an array-based approach for developing film processing methods, measuring performance characteristics, and establishing reproducibility. It also illustrates how temperature-dependent response data for varied metal/oxide compositions can be used to tailor a microsensor array for a given application.

  20. Temperature dependent diffusion and epitaxial behavior of oxidized Au/Ni/p-GaN ohmic contact

    International Nuclear Information System (INIS)

    Hu, C.Y.; Qin, Z.X.; Feng, Z.X.; Chen, Z.Z.; Ding, Z.B.; Yang, Z.J.; Yu, T.J.; Hu, X.D.; Yao, S.D.; Zhang, G.Y.

    2006-01-01

    The temperature dependent diffusion and epitaxial behavior of oxidized Au/Ni/p-GaN ohmic contact were studied with Rutherford backscattering spectroscopy/channeling (RBS/C) and synchrotron X-ray diffraction (XRD). It is found that the Au diffuses to the surface of p-GaN to form an epitaxial structure on p-GaN after annealing at 450 deg. C. At the same time, the O diffuses to the metal-semiconductor interface and forms NiO. Both of them are suggested to be responsible for the sharp decrease in the specific contact resistance (ρ c ) at 450 deg. C. At 500 deg. C, the epitaxial structure of Au develops further and the O also diffuses deeper into the interface. As a result, the ρ c reaches the lowest value at this temperature. However, when annealing temperature reaches 600 deg. C, part or all of the interfacial NiO is detached from the p-GaN and diffuses out, which cause the ρ c to increase greatly

  1. Anomalous interfacial tension temperature dependence of condensed phase drops in magnetic fluids

    Science.gov (United States)

    Ivanov, Aleksey S.

    2018-05-01

    Interfacial tension temperature dependence σ(T) of the condensed phase (drop-like aggregates) in magnetic fluids undergoing field induced phase transition of the "gas-liquid" type was studied experimentally. Numerical analysis of the experimental data has revealed the anomalous (if compared to ordinary one-component fluids) behavior of the σ(T) function for all tested magnetic colloid samples: the condensed phase drops at high T ≈ 75 C exhibit higher σ(T) than the drops condensed at low T ≈ 20 C. The σ(T) behavior is explained by the polydispersity of magnetic colloids: at high T, only the largest colloidal particles are able to take part in the field induced condensation; thus, the increase of T causes the growth of the average particle diameters inside the drop-like aggregates, what in its turn results in the growth of σ(T). The result is confirmed by qualitative theoretical estimations and qualitative experimental observation of the condensed phase "evaporation" process after the applied magnetic field is removed: the drops that are formed due to capillary instability of the drop-like aggregates retract by one order of magnitude faster at high T, and the evaporation of the drops slows down at high T.

  2. Computation of temperature-dependent legendre moments of a double-differential elastic cross section

    International Nuclear Information System (INIS)

    Arbanas, G.; Dunn, M.E.; Larson, N.M.; Leal, L.C.; Williams, M.L.; Becker, B.; Dagan, R.

    2011-01-01

    A general expression for temperature-dependent Legendre moments of a double-differential elastic scattering cross section was derived by Ouisloumen and Sanchez [Nucl. Sci. Eng. 107, 189-200 (1991)]. Attempts to compute this expression are hindered by the three-fold nested integral, limiting their practical application to just the zeroth Legendre moment of an isotropic scattering. It is shown that the two innermost integrals could be evaluated analytically to all orders of Legendre moments, and for anisotropic scattering, by a recursive application of the integration by parts method. For this method to work, the anisotropic angular distribution in the center of mass is expressed as an expansion in Legendre polynomials. The first several Legendre moments of elastic scattering of neutrons on 238 U are computed at T=1000 K at incoming energy 6.5 eV for isotropic scattering in the center of mass frame. Legendre moments of the anisotropic angular distribution given via Blatt-Biedenharn coefficients are computed at 1 keV. The results are in agreement with those computed by the Monte Carlo method. (author)

  3. Analysis of microwave heating of materials with temperature-dependent properties

    International Nuclear Information System (INIS)

    Ayappa, K.G.; Davis, H.T.; Davis, E.A.; Gordon, J.

    1991-01-01

    In this paper transient temperature profiles in multilayer slabs are predicted, by simultaneously solving Maxwell's equations with the heat conduction equation, using Galerkin-finite elements. It is assumed that the medium is homogeneous and has temperature-dependent dielectric and thermal properties. The method is illustrated with applications involving the heating of food and polymers with microwaves. The temperature dependence of dielectric properties affects the heating appreciably, as is shown by comparison with a constant property model

  4. Experimental determination of the temperature dependence of metallic work functions at low temperatures. Progress report

    International Nuclear Information System (INIS)

    Pipes, P.B.

    1977-01-01

    Progress made under ERDA Contract No. EY-76-S-02-2314.002 is described. Efforts to gain theoretical insight into the temperature dependence of the contact potential of Nb near the superconducting transition have only been qualitatively successful. Preliminary measurements of adsorbed 4 He gas on the temperature dependence of the contact potentials of metals were performed and compared with a previously developed theory

  5. A Temperature-Dependent Thermal Model of IGBT Modules Suitable for Circuit-Level Simulations

    DEFF Research Database (Denmark)

    Wu, Rui; Wang, Huai; Ma, Ke

    2014-01-01

    Thermal impedance of IGBT modules may vary with operating conditions due to that the thermal conductivity and heat capacity of materials are temperature dependent. This paper proposes a Cauer thermal model for a 1700 V/1000 A IGBT module with temperature-dependent thermal resistances and thermal ...... relevant reliability aspect performance. A test bench is built up with an ultra-fast infrared (IR) camera to validate the proposed thermal impedance model....

  6. Temperature dependence of 1H NMR relaxation time, T2, for intact and neoplastic plant tissues

    Science.gov (United States)

    Lewa, Czesław J.; Lewa, Maria

    Temperature dependences of the spin-spin proton relaxation time, T2, have been shown for normal and tumorous tissues collected from kalus culture Nicotiana tabacum and from the plant Kalanchoe daigremontiana. For neoplastic plant tissues, time T2 was increased compared to that for intact plants, a finding similar to that for animal and human tissues. The temperature dependences obtained were compared to analogous relations observed with animal tissues.

  7. Effect of temperature-dependent energy-level shifts on a semiconductor's Peltier heat

    International Nuclear Information System (INIS)

    Emin, D.

    1984-01-01

    The Peltier heat of a charge carrier in a semiconductor is calculated for the situation in which the electronic energy levels are temperature dependent. The temperature dependences of the electronic energy levels, generally observed optically, arise from their dependences on the vibrational energy of the lattice (e.g., as caused by thermal expansion). It has been suggested that these temperature dependences will typically have a major effect on the Peltier heat. The Peltier heat associated with a given energy level is a thermodynamic quantity; it is the product of the temperature and the change of the entropy of the system when a carrier is added in that level. As such, the energy levels cannot be treated as explicitly temperature dependent. The electron-lattice interaction causing the temperature dependence must be expressly considered. It is found that the carrier's interaction with the atomic vibrations lowers its electronic energy. However, the interaction of the carrier with the atomic vibrations also causes an infinitesimal lowering (approx.1/N) of each of the N vibrational frequencies. As a result, there is a finite carrier-induced increase in the average vibrational energy. Above the Debye temperature, this cancels the lowering of the carrier's electronic energy. Thus, the standard Peltier-heat formula, whose derivation generally ignores the temperature dependence of the electronic energy levels, is regained. This explains the apparent success of the standard formula in numerous analyses of electronic transport experiments

  8. On the theory of Heiser and Shercliff experiment. Part 2: MHD flow between two cylinders in strong radical magnetic field

    Science.gov (United States)

    Molokov, S. Y.; Allen, J. E.

    A magnetohydrodynamic (MHD) flow of conducting fluid between two concentric insulating cylinders in strong radial magnetic field which is parallel to a free surface of a fluid is investigated by means of matched asymptotic expansions method. The flow region is divided into various subregions and leading terms of asymptotic expansions as M tends towards infinity (M is the Hartmann number) of solutions of problems governing flow in these subregions are obtained.

  9. Temperature dependencies of Henry's law constants and octanol/water partition coefficients for key plant volatile monoterpenoids.

    Science.gov (United States)

    Copolovici, Lucian O; Niinemets, Ulo

    2005-12-01

    To model the emission dynamics and changes in fractional composition of monoterpenoids from plant leaves, temperature dependencies of equilibrium coefficients must be known. Henry's law constants (H(pc), Pa m3 mol(-1) and octanol/water partition coefficients (K(OW), mol mol(-1)) were determined for 10 important plant monoterpenes at physiological temperature ranges (25-50 degrees C for H(pc) and 20-50 degrees C for K(OW)). A standard EPICS procedure was established to determine H(pc) and a shake flask method was used for the measurements of K(OW). The enthalpy of volatilization (deltaH(vol)) varied from 18.0 to 44.3 kJ mol(-1) among the monoterpenes, corresponding to a range of temperature-dependent increase in H(pc) between 1.3- and 1.8-fold per 10 degrees C rise in temperature. The enthalpy of water-octanol phase change varied from -11.0 to -23.8 kJ mol(-1), corresponding to a decrease of K(OW) between 1.15- and 1.32-fold per 10 degrees C increase in temperature. Correlations among physico-chemical characteristics of a wide range of monoterpenes were analyzed to seek the ways of derivation of H(pc) and K(OW) values from other monoterpene physico-chemical characteristics. H(pc) was strongly correlated with monoterpene saturated vapor pressure (P(v)), and for lipophilic monoterpenes, deltaH(vol) scaled positively with the enthalpy of vaporization that characterizes the temperature dependence of P(v) Thus, P(v) versus temperature relations may be employed to derive the temperature relations of H(pc) for these monoterpenes. These data collectively indicate that monoterpene differences in H(pc) and K(OW) temperature relations can importantly modify monoterpene emissions from and deposition on plant leaves.

  10. Time and temperature dependence of cascade induced defect production in in situ experiments and computer simulation

    International Nuclear Information System (INIS)

    Ishino, Shiori

    1993-01-01

    Understanding of the defect production and annihilation processes in a cascade is important in modelling of radiation damage for establishing irradiation correlation. In situ observation of heavy ion radiation damage has a great prospect in this respect. Time and temperature dependence of formation and annihilation of vacancy clusters in a cascade with a time resolution of 30 ms has been studied with a facility which comprises a heavy ion accelerator and an electron microscope. Formation and annihilation rates of defect clusters have been separately measured by this technique. The observed processes have been analysed by simple kinetic equations, taking into account the sink effect of surface and the defect clusters themselves together with the annihilation process due to thermal emission of vacancies from the defect clusters. Another tool to study time and temperature dependence of defect production in a cascade is computer simulation. Recent results of molecular dynamics calculations on the temperature dependence of cascade evolution are presented, including directional and temperature dependence of the lengths of replacement collision sequences, temperature dependence of the process to reach thermal equilibrium and so on. These results are discussed under general time frame of radiation damage evolution covering from 10 -15 to 10 9 s, and several important issues for the general understanding have been identified. (orig.)

  11. Temperature dependence of 1H NMR chemical shifts and its influence on estimated metabolite concentrations.

    Science.gov (United States)

    Wermter, Felizitas C; Mitschke, Nico; Bock, Christian; Dreher, Wolfgang

    2017-12-01

    Temperature dependent chemical shifts of important brain metabolites measured by localised 1 H MRS were investigated to test how the use of incorrect prior knowledge on chemical shifts impairs the quantification of metabolite concentrations. Phantom measurements on solutions containing 11 metabolites were performed on a 7 T scanner between 1 and 43 °C. The temperature dependence of the chemical shift differences was fitted by a linear model. Spectra were simulated for different temperatures and analysed by the AQSES program (jMRUI 5.2) using model functions with chemical shift values for 37 °C. Large differences in the temperature dependence of the chemical shift differences were determined with a maximum slope of about ±7.5 × 10 -4  ppm/K. For 32-40 °C, only minor quantification errors resulted from using incorrect chemical shifts, with the exception of Cr and PCr. For 1-10 °C considerable quantification errors occurred if the temperature dependence of the chemical shifts was neglected. If 1 H MRS measurements are not performed at 37 °C, for which the published chemical shift values have been determined, the temperature dependence of chemical shifts should be considered to avoid systematic quantification errors, particularly for measurements on animal models at lower temperatures.

  12. Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells.

    Science.gov (United States)

    Foxman, Ellen F; Storer, James A; Fitzgerald, Megan E; Wasik, Bethany R; Hou, Lin; Zhao, Hongyu; Turner, Paul E; Pyle, Anna Marie; Iwasaki, Akiko

    2015-01-20

    Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33-35 °C) than at core body temperature (37 °C). To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C. Mouse airway cells infected with mouse-adapted rhinovirus 1B exhibited a striking enrichment in expression of antiviral defense response genes at 37 °C relative to 33 °C, which correlated with significantly higher expression levels of type I and type III IFN genes and IFN-stimulated genes (ISGs) at 37 °C. Temperature-dependent IFN induction in response to rhinovirus was dependent on the MAVS protein, a key signaling adaptor of the RIG-I-like receptors (RLRs). Stimulation of primary airway cells with the synthetic RLR ligand poly I:C led to greater IFN induction at 37 °C relative to 33 °C at early time points poststimulation and to a sustained increase in the induction of ISGs at 37 °C relative to 33 °C. Recombinant type I IFN also stimulated more robust induction of ISGs at 37 °C than at 33 °C. Genetic deficiency of MAVS or the type I IFN receptor in infected airway cells permitted higher levels of viral replication, particularly at 37 °C, and partially rescued the temperature-dependent growth phenotype. These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.

  13. Temperature dependence of differential conductance in Co-based Heusler alloy Co2TiSn and superconductor Pb junctions

    Science.gov (United States)

    Ooka, Ryutaro; Shigeta, Iduru; Umetsu, Rie Y.; Nomura, Akiko; Yubuta, Kunio; Yamauchi, Touru; Kanomata, Takeshi; Hiroi, Masahiko

    2018-05-01

    We investigated temperature dependence of differential conductance G (V) in planar junctions consisting of Co-based Heusler alloy Co2TiSn and superconductor Pb. Ferromagnetic Co2TiSn was predicted to be half-metal by first-principles band calculations. The spin polarization P of Co2TiSn was deduced to be 60.0% at 1.4 K by the Andreev reflection spectroscopy. The G (V) spectral shape was smeared gradually with increasing temperature and its structure was disappeared above the superconducting transition temperature Tc. Theoretical model analysis revealed that the superconducting energy gap Δ was 1.06 meV at 1.4 K and the Tc was 6.8 K , indicating that both values were suppressed from bulk values. However, the temperature dependent Δ (T) behavior was in good agreement with that of the Bardeen-Cooper-Schrieffer (BCS) theory. The experimental results exhibit that the superconductivity of Pb attached to half-metallic Co2TiSn was kept the conventional BCS mechanism characterized strong-coupling superconductors while its superconductivity was slightly suppressed by the superconducting proximity effect at the Co2TiSn/Pb interface.

  14. Muon-spin rotation (. mu. SR) study of the temperature dependence of the London penetration depth in copper oxide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Keller, H.; Kuendig, W.; Savic, I.M.; Simmler, H.; Staeuble-Puempin, B.; Warden, M.; Zech, D.; Zimmermann, P. (Physik-Inst., Univ. Zurich (Germany)); Kaldis, E.; Karpinski, J.; Rusiecki, S. (Lab. fuer Festkoerperphysik, ETH Zurich (Switzerland)); Brewer, J.H.; Riseman, T.M.; Schneider, J.W. (TRIUMF and Dept. of Physics, Univ. of British Columbia, Vancouver (Canada)); Maeno, Y.; Rossel, C. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland))

    1991-12-01

    A {mu}SR study of the temperature dependence of the London penetration depth {lambda} in sintered samples of YBa{sub 2}Cu{sub 3}O{sub x} (with various oxygen contents x), YBa{sub 2}Cu{sub 4}O{sub 8} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} is presented. It is found that the temperature behavior of {lambda} of all these cuprate superconductors is consistent with conventional s-wave pairing. However, there are significant differences concerning the exact temperature dependence of {lambda} in these materials. In YBa{sub 2}Cu{sub 3}O{sub x} with high x, the behavior of {lambda}(T) is well described by the two-fluid model (strong coupling), whereas {lambda}(T) in YBa{sub 2}Cu{sub 3}O{sub x} with low x, YBa{sub 2}Cu{sub 4}O{sub 8} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} is in better agreement with weak-coupling BCS theory. Possible reasons for the different temperature behavior of {lambda} in these materials are discussed. (orig.).

  15. Assessing the Temperature Dependence of Narrow-Band Raman Water Vapor Lidar Measurements: A Practical Approach

    Science.gov (United States)

    Whiteman, David N.; Venable, Demetrius D.; Walker, Monique; Cardirola, Martin; Sakai, Tetsu; Veselovskii, Igor

    2013-01-01

    Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author.

  16. Microtremor Array Measurement Survey and Strong Ground Motion observation activities of The SATREPS, MarDiM project -Part 2-

    Science.gov (United States)

    Citak, Seckin; Karagoz, Ozlem; Chimoto, Kosuke; Ozel, Oguz; Yamanaka, Hiroaki; Arslan, Safa; Aksahin, Bengi; Hatayama, Ken; Ohori, Michihiro; Hori, Muneo

    2016-04-01

    Since 1939, devastating earthquakes with magnitude greater than seven ruptured North Anatolian Fault (NAF) westward, starting from 1939 Erzincan (Ms=7.9) at the eastern Turkey and including the latest 1999 Izmit-Golcuk (Ms=7.4) and the Duzce (Ms=7.2) earthquakes in the eastern Marmara region, Turkey. On the other hand, the west of the Sea of Marmara an Mw7.4 earthquake ruptured the NAF' s Ganos segment in 1912. The only un-ruptured segments of the NAF in the last century are within the Sea of Marmara, and are identified as a "seismic gap" zone that its rupture may cause a devastating earthquake. In order to unravel the seismic risks of the Marmara region a comprehensive multidisciplinary research project The MarDiM project "Earthquake And Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey", has already been started since 2003. The project is conducted in the framework of "Science and Technology Research Partnership for Sustainable Development (SATREPS)" sponsored by Japan Science and Technology Agency (JST) and Japan International Cooperation Agency (JICA). One of the main research field of the project is "Seismic characterization and damage prediction" which aims to improve the prediction accuracy of the estimation of the damages induced by strong ground motions and tsunamis based on reliable source parameters, detailed deep and shallow velocity structure and building data. As for detailed deep and shallow velocity structure microtremor array measurement surveys were conducted in Zeytinburnu district of Istanbul, Tekirdag, Canakkale and Edirne provinces at about 109 sites on October 2013, September 2014 and 2015. Also in September 2014, 11 accelerometer units were installed mainly in public buildings in both Zeytinburnu and Tekirdag area and are currently in operation. Each accelerometer unit compose of a Network Sensor (CV-374A) by Tokyo Sokushin, post processing PC for data storage and power supply unit. The Network Sensor (CV-374

  17. Microtremor Array Measurement Survey and Strong Ground Motion observation activities of The SATREPS, MarDiM project -Part 3-

    Science.gov (United States)

    Citak, Seckin; Safa Arslan, Mehmet; Karagoz, Ozlem; Chimoto, Kosuke; Ozel, Oguz; Yamanaka, Hiroaki; Behiye Aksahin, Bengi; Hatayama, Ken; Sahin, Abdurrahman; Ohori, Michihiro; Safak, Erdal; Hori, Muneo

    2017-04-01

    Since 1939, devastating earthquakes with magnitude greater than seven ruptured North Anatolian Fault (NAF) westward, starting from 1939 Erzincan (Ms=7.9) at the eastern Turkey and including the latest 1999 Izmit-Golcuk (Ms=7.4) and the Duzce (Ms=7.2) earthquakes in the eastern Marmara region, Turkey. On the other hand, the west of the Sea of Marmara an Mw7.4 earthquake ruptured the NAF' s Ganos segment in 1912. The only un-ruptured segments of the NAF in the last century are within the Sea of Marmara, and are identified as a "seismic gap" zone that its rupture may cause a devastating earthquake. In order to unravel the seismic risks of the Marmara region a comprehensive multidisciplinary research project The MarDiM project "Earthquake And Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey", has already been started since 2003. The project is conducted in the framework of "Science and Technology Research Partnership for Sustainable Development (SATREPS)" sponsored by Japan Science and Technology Agency (JST) and Japan International Cooperation Agency (JICA). One of the main research field of the project is "Seismic characterization and damage prediction" which aims to improve the prediction accuracy of the estimation of the damages induced by strong ground motions and tsunamis based on reliable source parameters, detailed deep and shallow velocity structure and building data. As for detailed deep and shallow velocity structure microtremor array measurement surveys were conducted in Zeytinburnu district of Istanbul, Tekirdag, Canakkale and Edirne provinces at about 140 sites on October 2013, September 2014, 2015 and 2016. Also in September 2014, 11 accelerometer units were installed mainly in public buildings in both Zeytinburnu and Tekirdag area and are currently in operation. Each accelerometer unit compose of a Network Sensor (CV-374A) by Tokyo Sokushin, post processing PC for data storage and power supply unit. The Network Sensor

  18. Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)] [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2009-09-14

    Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

  19. Optical power limiting and transmitting properties of cadmium iodide single crystals: Temperature dependence

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2009-01-01

    Optical limiting properties of the single crystals of cadmium iodide are investigated using ns laser pulses. It is found that the transmissions in the crystals increase with increasing temperature. However, they limit the transmissions at high input powers. The limiting power is found to be higher at higher temperature. From the measured transmission data, the photon absorption coefficients are estimated. The temperature dependence of the coefficients shows a decrease in magnitude with increasing temperature. This might be due to the temperature-dependent bandgap shift of the material. The results demonstrate that the cadmium iodide single crystals are promising materials for applications in optical power limiting devices.

  20. Temperature dependence of residual electrical resistivity of Cu-Au in pseudopotential approximation

    International Nuclear Information System (INIS)

    Khwaja, F.A.; Ahmed, I.; Shaukat, A.

    1986-08-01

    The problem of temperature dependence of residual electrical resistivity of Cu-Au system is re-examined in the light of static distortion and thermal vibration of the lattice along with the short-range-order of atoms above critical temperature. The extended version of Ziman's formula for resistivity obtained yields a unified version for the calculation of resistivity in pseudopotential approximation. The temperature dependence of the quantity Δρ/ρ in this framework for Cu-Au system is found to be in better agreement with the experimental data as compared to previous calculation. (author)

  1. Temperature-dependence of Threshold Current Density-Length Product in Metallization Lines: A Revisit

    International Nuclear Information System (INIS)

    Duryat, Rahmat Saptono; Kim, Choong-Un

    2016-01-01

    One of the important phenomena in Electromigration (EM) is Blech Effect. The existence of Threshold Current Density-Length Product or EM Threshold has such fundamental and technological consequences in the design, manufacture, and testing of electronics. Temperature-dependence of Blech Product had been thermodynamically established and the real behavior of such interconnect materials have been extensively studied. The present paper reviewed the temperature-dependence of EM threshold in metallization lines of different materials and structure as found in relevant published articles. It is expected that the reader can see a big picture from the compiled data, which might be overlooked when it was examined in pieces. (paper)

  2. DETERMINATION OF TEMPERATURE DISTRIBUTION FOR ANNULAR FINS WITH TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY BY HPM

    Directory of Open Access Journals (Sweden)

    Davood Domairry Ganji

    2011-01-01

    Full Text Available In this paper, homotopy perturbation method has been used to evaluate the temperature distribution of annular fin with temperature-dependent thermal conductivity and to determine the temperature distribution within the fin. This method is useful and practical for solving the nonlinear heat transfer equation, which is associated with variable thermal conductivity condition. The homotopy perturbation method provides an approximate analytical solution in the form of an infinite power series. The annular fin heat transfer rate with temperature-dependent thermal conductivity has been obtained as a function of thermo-geometric fin parameter and the thermal conductivity parameter describing the variation of the thermal conductivity.

  3. The Temperature Dependence of the Debye-Waller Factor of Magnesium

    DEFF Research Database (Denmark)

    Sledziewska-Blocka, D.; Lebech, Bente

    1976-01-01

    The temperature dependence of the average Debye-Waller factor for magnesium was measured by means of neutron diffraction spectrometry. The experimental results obtained in the temperature range from 5 to 256 K are compared with theoretical calculations, using the harmonic and quasi-harmonic appro......The temperature dependence of the average Debye-Waller factor for magnesium was measured by means of neutron diffraction spectrometry. The experimental results obtained in the temperature range from 5 to 256 K are compared with theoretical calculations, using the harmonic and quasi......-harmonic approximations and results of previous experiments....

  4. Temperature Dependence of Short-Range Order in β-Brass

    DEFF Research Database (Denmark)

    Dietrich, O.W.; Als-Nielsen, Jens Aage

    1967-01-01

    Critical scattering of neutrons around the superlattice reflections (1, 0, 0) and (1, 1, 1) from a single crystal of beta-brass has been measured at temperatures from 2 to 25deg C above the transition temperature. The temperature dependence of the critical peak intensity, proportional to the susc......Critical scattering of neutrons around the superlattice reflections (1, 0, 0) and (1, 1, 1) from a single crystal of beta-brass has been measured at temperatures from 2 to 25deg C above the transition temperature. The temperature dependence of the critical peak intensity, proportional...

  5. RECENT STRONG EARTHQUAKES IN CENTRAL ASIA: REGULAR TECTONOPHYSICAL FEATURES OF LOCATIONS IN THE STRUCTURE AND GEODYNAMICS OF THE LITHOSPHERE. PART 1. MAIN GEODYNAMIC FACTORS PREDETERMINING LOCATIONS OF STRONG EARTHQUAKES IN THE STRUCTURE OF THE LITHOSPHER

    Directory of Open Access Journals (Sweden)

    S. I. Sherman

    2015-01-01

    Full Text Available Studying locations of strong earthquakes (М≥8 in space and time in Central Asia has been among top prob-lems for many years and still remains challenging for international research teams. The authors propose a new ap-proach that requires changing the paradigm of earthquake focus – solid rock relations, while this paradigm is a basis for practically all known physical models of earthquake foci. This paper describes the first step towards developing a new concept of the seismic process, including generation of strong earthquakes, with reference to specific geodynamic features of the part of the study region wherein strong earthquakes were recorded in the past two centuries. Our analysis of the locations of М≥8 earthquakes shows that in the past two centuries such earthquakes took place in areas of the dynamic influence of large deep faults in the western regions of Central Asia. In the continental Asia, there is a clear submeridional structural boundary (95–105°E between the western and eastern regions, and this is a factor controlling localization of strong seismic events in the western regions. Obviously, the Indostan plate’s pressure from the south is an energy source for such events. The strong earthquakes are located in a relatively small part of the territory of Central Asia (i.e. the western regions, which is significantly different from its neighbouring areas at the north, east and west, as evidenced by its specific geodynamic parameters. (1 The crust is twice as thick in the western regions than in the eastern regions. (2 In the western regions, the block structures re-sulting from the crust destruction, which are mainly represented by lense-shaped forms elongated in the submeridio-nal direction, tend to dominate. (3 Active faults bordering large block structures are characterized by significant slip velocities that reach maximum values in the central part of the Tibetan plateau. Further northward, slip velocities decrease

  6. Temperature Dependence of Respiration in Larvae and Adult Colonies of the Corals Acropora tenuis and Pocillopora damicornis

    Directory of Open Access Journals (Sweden)

    Dwi Haryanti

    2015-06-01

    Full Text Available Although algal symbionts can become a source of reactive oxygen species under stressful conditions, symbiotic planulae of the coral Pocillopora damicornis are highly tolerant to thermal stress compared with non-symbiotic planulae of Acropora tenuis. As a first step to understand how P. damicornis planulae attain high stress tolerance, we compared the respiration rate and temperature dependence between symbiotic planulae of P. damicornis and non-symbiotic planulae of A. tenuis, as well as between larvae and adult branches within each species. Larvae and adult branches of both species had similar temperature dependency of respiration rate, with the temperature coefficient (Q10 values of about 2. Planula larvae of P. damicornis had a significantly lower respiration rate than that of A. tenuis larvae at 25–30 °C, but not at 32 °C, whereas adult branches of P. damicornis had a significantly higher respiration rate than that of A. tenuis branches at all temperatures. Thus, P. damicornis larvae appear to be capable of reducing their respiration rate to a greater extent than A. tenuis larvae, which could partly explain why P. damicornis larvae had high survivorship under thermal stress, although other antioxidant or photoprotective mechanisms should be investigated in the future.

  7. Study of the temperature dependence of the bainitic transformation rate in a multiphase TRIP-assisted steel

    International Nuclear Information System (INIS)

    Girault, E.; Ratchev, P.; Van Humbeeck, J.; Verlinden, B.; Aernoudt, E.

    1999-01-01

    A prerequisite to the development of multiphase TRIP-assisted steels is a good understanding of the bainitic transformation that takes place during the related thermo-mechanical processing. In this framework, the present paper proposes to investigate the formation of bainite when originating from intercritical austenite in a Si bearing steel. The experimental results suggest the contribution of a martensitic type mechanism to the transformation process. Yet, the overall bainitic reaction rates are found to strongly depend on the holding temperature. This original kinetics is correlated with the typical microstructure the steel exhibits after the intercritical annealing stage. To this extent, the crucial role of the adjacent development of bainitic ferrite for the observed temperature dependence is discussed. (orig.)

  8. Temperature dependence of ac response in diluted half-metallic CrO{sub 2} powder compact

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yajie; Zhang Xiaoyu; Cai Tianyi; Li Zhenya

    2004-10-06

    We present a study on temperature dependence of impedance spectra of the cold-pressed chromium dioxide (CrO{sub 2})-titanic dioxide (TiO{sub 2}) composite over the temperature range of 77-300 K, and over the frequency range of 40 Hz-500 kHz. The microstructure of the sample is analyzed using transmission electron microscopy (TEM), SEM and X-ray diffraction (XRD). The impedance spectra exhibit a strong dependence upon temperature. By evaluating the ac electricity behavior of the composite, we find the experimental data are successfully described by a power-law behavior {sigma}{sub ac}=A(T){omega}{sup s}, in which the frequency exponent s shows slightly greater than a universal value (0{<=}s{<=}1), and rises approximately linearly with temperature over a broad range of low temperature.

  9. Temperature-dependent dynamic mechanical properties of magnetorheological elastomers under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Benxiang, E-mail: jubenxiang@qq.com [National Instrument Functional Materials Engineering Technology Research Center, Chongqing 400707 (China); Tang, Rui; Zhang, Dengyou; Yang, Bailian [National Instrument Functional Materials Engineering Technology Research Center, Chongqing 400707 (China); Yu, Miao; Liao, Changrong [College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2015-01-15

    Both anisotropic and isotropic magnetorheological elastomer (MRE) samples were fabricated by using as-prepared polyurethane (PU) matrix and carbonyl iron particles. Temperature-dependent dynamic mechanical properties of MRE were investigated and analyzed. Due to the unique structural features of as-prepared matrix, temperature has a greater impact on the properties of as-prepared MRE, especially isotropic MRE. With increasing of temperature and magnetic field, MR effect of isotropic MRE can reach up to as high as 4176.5% at temperature of 80 °C, and the mechanism of the temperature-dependent in presence of magnetic field was discussed. These results indicated that MRE is a kind of temperature-dependent material, and can be cycled between MRE and MR plastomer (MRP) by varying temperature. - Highlights: • Both anisotropic and isotropic MRE were fabricated by using as-prepared matrix. • Temperature-dependent properties of MRE under magnetic field were investigated. • As-prepared MRE can transform MRE to MRP by adjusting temperature.

  10. Transient thermal stresses in multiple connected region exhibiting temperature dependence of material properties

    International Nuclear Information System (INIS)

    Sugano, Yoshihiro; Maekawa, Toshiya.

    1983-01-01

    The examples of the analysis of thermal stress in multiple connection regions such as heat exchangers, nuclear reactor cores, ingot cases and polygonal region with elliptic holes are not few, but the temperature dependence of material constants was neglected in these researches because of the difficulty of analysis though the industrial problems related to thermal stress are apt to occur in the condition of relatively large temperature gradient. Also, the analysis of heat conduction problems taking the temperature dependence of material constants into account was limited to one-dimensional problems for which Kirchhoff's transmission can be used. The purpose of this study is to derive the equation of condition which assures the one-value property of rotation and displacement, taking the temperature dependence of material constants into account, and to complete the formulation of the plane thermal stress problems in multiple connection regions by stress function method. Also the method of numerical analysis using difference method is shown to examine the effectiveness of various formulated equations and the effect of the temperature dependence of material constants on temperature and thermal stress. The example of numerical calculation on a thin rectangular plate with a rectangular hole is shown. (Kako, I.)

  11. Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

    KAUST Repository

    Holding, J. M.; Duarte, Carlos M.; Sanz-Martí n, M.; Mesa, E.; Arrieta, J M; Chierici, M.; Hendriks, I.  E.; Garcí a-Corral, L. S.; Regaudie-de-Gioux, A.; Delgado, A.; Reigstad, M.; Wassmann, P.; Agusti, Susana

    2015-01-01

    production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO2 enhances GPP (by a factor of up to ten) over a range

  12. Effect of linear temperature dependence of thermoelectric properties on energy conversion efficiency

    International Nuclear Information System (INIS)

    Yamashita, Osamu

    2008-01-01

    New thermal rate equations were developed by taking the temperature dependences of the electrical resistivity ρ and thermal conductivity κ of the thermoelectric (TE) materials into the thermal rate equations on the assumption that they vary linearly with temperature T. The relative energy conversion efficiency η/η 0 for a single TE element was formulated by approximate analysis, where η and η 0 are the energy conversion efficiencies derived from the new and conventional thermal rate equations, respectively. Applying it to Si-Ge alloys, the temperature dependence of ρ is stronger than that of κ, so the former has a more significant effect on η/η 0 than the latter. However, the degree of contribution from both of them to η/η 0 was a little lower than 1% at the temperature difference ΔT of 600 K. When the temperature dependence of κ was increased to become equal to that of ρ, however, it was found that η/η 0 is increased by about 10% at ΔT = 600 K. It is clarified here that the temperature dependences of ρ and κ are also important factors for an improvement in η

  13. Measured Temperature Dependence of the cos-phi Conductance in Josephson Tunnel Junctions

    DEFF Research Database (Denmark)

    Sørensen, O. H.; Mygind, Jesper; Pedersen, Niels Falsig

    1977-01-01

    The temperature dependence of the cosϕ conductance in Sn-O-Sn Josephson tunnel junctions has been measured just below the critical temperature, Tc. From the resonant microwave response at the junction plasma frequency as the temperature is decreased from Tc it is deduced that the amplitude of the...

  14. Temperature dependence of the in situ widths of a rotating condensate in one dimensional optical potential

    International Nuclear Information System (INIS)

    Hassan, Ahmed S.; Soliman, Shemi S.M.

    2016-01-01

    In this paper, a conventional method of quantum statistical mechanics is used to study the temperature dependence of the in situ widths of a rotating condensate bosons in 1D optical potential. We trace the experimentally accessible parameters for which the temperature dependence of the in situ widths becomes perceivable. The calculated results showed that the temperature dependence of the in situ widths is completely different from that of a rotating condensate or trapped bosons in the optical lattice separately. The z-width shows distinct behavior from x- and y-widths due to the rotation effect. The obtained results provide useful qualitative theoretical results for future Bose Einstein condensation experiments in such traps. - Highlights: • The temperature dependence of the in situ widths of a rotating condensate boson in 1D optical potential is investigated. • We trace the experimentally accessible parameters for which the in situ widths become perceivable. • The above mentioned parameters exhibit a characteristic rotation rate and optical potential depth dependence. • Characteristic dependence of the effective widths on temperature is investigated. • Our results provide useful qualitatively and quantitative theoretical results for experiments in various traps.

  15. Observed and simulated temperature dependence of the liquid water path of low clouds

    Energy Technology Data Exchange (ETDEWEB)

    Del Genio, A.D.; Wolf, A.B. [NASA Goddard Institute for Space Studies, New York, NY (United States)

    1996-04-01

    Data being acquired at the Atmospheric Radiation Measurement (ARM) Southern great Plains (SGP) Cloud and Radiation Testbed (CART) site can be used to examine the factors determining the temperature dependence of cloud optical thickness. We focus on cloud liquid water and physical thickness variations which can be derived from existing ARM measurements.

  16. A temperature dependent simple spice based modeling platform for power IGBT modules

    NARCIS (Netherlands)

    Sfakianakis, G.; Nawaz, M.; Chimento, F.

    2014-01-01

    This paper deals with the development of a PSpice based temperature dependent modelling platform for the evaluation of silicon based IGBT power modules. The developed device modelling platform is intended to be used for the design and assessment of converter valves/cells for potential high power

  17. Demonstrating the Temperature Dependence of Density via Construction of a Galilean Thermometer

    Science.gov (United States)

    Priest, Marie A.; Padgett, Lea W.; Padgett, Clifford W.

    2011-01-01

    A method for the construction of a Galilean thermometer out of common chemistry glassware is described. Students in a first-semester physical chemistry (thermodynamics) class can construct the Galilean thermometer as an investigation of the thermal expansivity of liquids and the temperature dependence of density. This is an excellent first…

  18. Temperature dependence of UV radiation effects in Arctic and temperate isolates of three red macrophytes

    NARCIS (Netherlands)

    van de Poll, W.H.; Eggert, A.; Buma, A.G.J.; Breeman, Arno

    The temperature dependence of UV effects was studied for Arctic and temperate isolates of the red macrophytes Palmaria palmata, Coccotylus truncatus and Phycodrys rubens. The effects of daily repeated artificial ultraviolet B and A radiation (UVBR: 280-320 nm, UVAR: 320-400 nm) treatments were

  19. Preparation and temperature dependence of electrostriction properties for PMN-based composite ceramics

    International Nuclear Information System (INIS)

    Zhao Jingbo; Qu Shaobo; Du Hongliang; Zheng Yanju; Xu Zhuo

    2009-01-01

    Both low- and high-temperature units were prepared by columbite precursor method, and Pb(Mg 1/3 Nb 2/3 )O 3 (PMN)-based ferroelectric composite ceramics were prepared by conventional method, baking-block method and coating method, respectively. The effects of preparation methods on dielectric and electrostriction properties as well as the temperature-dependence property of the obtained composite ceramics were studied. The results show that compared with the samples prepared by traditional blend sintering method, of the samples prepared by baking-block and coating methods have much better dielectric and electrostriction properties. For those prepared by baking-block method, the electrostriction temperature-dependence properties are good in the range of 20-60 deg. C. For those prepared by coating method, the dielectric temperature-dependence properties are also good in the broad range of -30 to 70 deg. C, and the electrostriction temperature properties are better than those prepared by blending-block. Compared with the traditional blending sintering method, the dielectric and electrostriction temperature-dependence properties are much better, which effectively solves the problem of temperature properties existing in present engineering applications.

  20. Temperature dependence of electron mean free path in molybdenum from ultrasonic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Almond, D P; Detwiler, D A; Rayne, J A [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

    1975-09-08

    The temperature dependence of the electronic mean free path in molybdenum has been obtained from ultrasonic attenuation measurements.For temperature up to 30 K a T/sup -2/ law is followed suggesting the importance of electron-electron scattering in the attenuation mechanism.

  1. Temperature-dependent built-in potential in organic semiconductor devices

    NARCIS (Netherlands)

    Kemerink, M.; Kramer, J.M.; Gommans, H.H.P.; Janssen, R.A.J.

    2006-01-01

    The temperature dependence of the built-in voltage of organic semiconductor devices is studied. The results are interpreted using a simple analytical model for the band bending at the electrodes. It is based on the notion that, even at zero current, diffusion may cause a significant charge density

  2. A simple equation for describing the temperature dependent growth of free-floating macrophytes

    NARCIS (Netherlands)

    Heide, van Tj.; Roijackers, R.M.M.; Nes, van E.H.; Peeters, E.T.H.M.

    2006-01-01

    Temperature is one of the most important factors determining growth rates of free-floating macrophytes in the field. To analyse and predict temperature dependent growth rates of these pleustophytes, modelling may play an important role. Several equations have been published for describing

  3. Temperature dependence of the superconducting proximity effect quantified by scanning tunneling spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Stępniak

    2015-01-01

    Full Text Available Here, we present the first systematic study on the temperature dependence of the extension of the superconducting proximity effect in a 1–2 atomic layer thin metallic film, surrounding a superconducting Pb island. Scanning tunneling microscopy/spectroscopy (STM/STS measurements reveal the spatial variation of the local density of state on the film from 0.38 up to 1.8 K. In this temperature range the superconductivity of the island is almost unaffected and shows a constant gap of a 1.20 ± 0.03 meV. Using a superconducting Nb-tip a constant value of the proximity length of 17 ± 3 nm at 0.38 and 1.8 K is found. In contrast, experiments with a normal conductive W-tip indicate an apparent decrease of the proximity length with increasing temperature. This result is ascribed to the thermal broadening of the occupation of states of the tip, and it does not reflect an intrinsic temperature dependence of the proximity length. Our tunneling spectroscopy experiments shed fresh light on the fundamental issue of the temperature dependence of the proximity effect for atomic monolayers, where the intrinsic temperature dependence of the proximity effect is comparably weak.

  4. Temperature Dependence and Magnetic Properties of Injection Molding Tool Materials Used in Induction Heating

    DEFF Research Database (Denmark)

    Guerrier, Patrick; Nielsen, Kaspar Kirstein; Hattel, Jesper Henri

    2015-01-01

    To analyze the heating phase of an induction heated injection molding tool precisely, the temperature-dependent magnetic properties, B–H curves, and the hysteresis loss are necessary for the molding tool materials. Hence, injection molding tool steels, core materials among other materials have...

  5. Temperature dependence of the cosphi conductance in Josephson tunnel junctions determined from plasma resonance experiments

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sørensen, O. H.; Mygind, Jesper

    1978-01-01

    The microwave response at 9 GHz of Sn-O-Sn tunnel-junction current biased at zero dc voltage has been measured just below the critical temperature Tc of the Sn films. The temperature dependence of the cosφ conductance is determined from the resonant response at the junction plasma frequency fp...

  6. Unravelling the size and temperature dependence of exciton lifetimes in colloidal ZnSe quantum dots

    NARCIS (Netherlands)

    Eilers, Joren; Van Hest, Jacobine; Meijerink, A; Donega, Celso De Mello

    2014-01-01

    We report on the temperature dependence of the band-edge photoluminescence decay of organically capped colloidal ZnSe quantum dots (QDs) in the size range from 4.0 to 7.5 nm. A similar trend is observed for all investigated sizes: the decay time is short (∼5 ns) above 20 K and increases sharply

  7. Temperature dependence of the magnetization of disc shaped NiO nanoparticles

    DEFF Research Database (Denmark)

    Klausen, Stine Nyborg; Lindgard, P.A.; Lefmann, Kim

    2002-01-01

    as a temperature dependent contribution of a structural peak in contrast to bulk NiO. The two magnetic signals vanish at the same temperature. The data are interpreted on the basis of an extended mean field model on disc shaped NiO particles. This model includes the finite size dependence of the effective field...

  8. Study on the effect of testing machine rigidity on strength and ductility temperature dependences obtained

    International Nuclear Information System (INIS)

    Krashchenko, V.P.; Statsenko, V.E.; Rudnitskij, N.P.

    1984-01-01

    Investigation procedures are described for rigidity of testing machines and mechanical properties of tantalum and nickel in the temperature range 293-1873K. Temperature dependences are presented for strength characteristics of the investigated materials obtained with the use of installations of different rigidity. Dependence analysis is carried out and recommendations are given as to the characteristics application

  9. Temperature-Dependent Effects of Cutaneous Bacteria on a Frog’s Tolerance of Fungal Infection

    Directory of Open Access Journals (Sweden)

    Matthew J. Robak

    2018-03-01

    Full Text Available Defense against pathogens is one of many benefits that bacteria provide to animal hosts. A clearer understanding of how changes in the environment affect the interactions between animals and their microbial benefactors is needed in order to predict the impact and dynamics of emerging animal diseases. Due to its dramatic effects on the physiology of animals and their pathogens, temperature may be a key variable modulating the level of protection that beneficial bacteria provide to their animal hosts. Here we investigate how temperature and the makeup of the skin microbial community affect the susceptibility of amphibian hosts to infection by Batrachochytrium dendrobatidis (Bd, one of two fungal pathogens known to cause the disease chytridiomycosis. To do this, we manipulated the skin bacterial communities of susceptible hosts, northern cricket frogs (Acris crepitans, prior to exposing these animals to Bd under two different ecologically relevant temperatures. Our manipulations included one treatment where antibiotics were used to reduce the skin bacterial community, one where the bacterial community was augmented with the antifungal bacterium, Stenotrophomonas maltophilia, and one in which the frog’s skin bacterial community was left intact. We predicted that frogs with reduced skin bacterial communities would be more susceptible (i.e., less resistant to and/or tolerant of Bd infection, and frogs with skin bacterial communities augmented with the known antifungal bacterium would be less susceptible to Bd infection and chytridiomycosis. However, we also predicted that this interaction would be temperature dependent. We found a strong effect of temperature but not of skin microbial treatment on the probability and intensity of infection in Bd-exposed frogs. Whether temperature affected survival; however, it differed among our skin microbial treatment groups, with animals having more S. maltophilia on their skin surviving longer at 14 but not at

  10. Resistor capacitor, primitive variable solution of buoyant fluid flow within an enclosure with highly temperature dependent viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Burns, S.P. [Texas Univ., Austin, TX (United States); Gianoulakis, S.E. [Sandia National Labs., Albuquerque, NM (United States)

    1995-07-01

    A numerical solution for buoyant natural convection within a square enclosure containing a fluid with highly temperature dependent viscosity is presented. Although the fluid properties employed do not represent any real fluid, the large variation in the fluid viscosity with temperature is characteristic of turbulent flow modeling with eddy-viscosity concepts. Results are obtained using a primitive variable formulation and the resistor method. The results presented include velocity, temperature and pressure distributions within the enclosure as well as shear stress and heat flux distributions along the enclosure walls. Three mesh refinements were employed and uncertainty values are suggested for the final mesh refinement. These solutions are part of a contributed benchmark solution set for the subject problem.

  11. Semi-empirical model for the threshold voltage of a double implanted MOSFET and its temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Arora, N D

    1987-05-01

    A simple and accurate semi-empirical model for the threshold voltage of a small geometry double implanted enhancement type MOSFET, especially useful in a circuit simulation program like SPICE, has been developed. The effect of short channel length and narrow width on the threshold voltage has been taken into account through a geometrical approximation, which involves parameters whose values can be determined from the curve fitting experimental data. A model for the temperature dependence of the threshold voltage for the implanted devices has also been presented. The temperature coefficient of the threshold voltage was found to change with decreasing channel length and width. Experimental results from various device sizes, both short and narrow, show very good agreement with the model. The model has been implemented in SPICE as part of the complete dc model.

  12. Progressive failure site generation in AlGaN/GaN high electron mobility transistors under OFF-state stress: Weibull statistics and temperature dependence

    International Nuclear Information System (INIS)

    Sun, Huarui; Bajo, Miguel Montes; Uren, Michael J.; Kuball, Martin

    2015-01-01

    Gate leakage degradation of AlGaN/GaN high electron mobility transistors under OFF-state stress is investigated using a combination of electrical, optical, and surface morphology characterizations. The generation of leakage “hot spots” at the edge of the gate is found to be strongly temperature accelerated. The time for the formation of each failure site follows a Weibull distribution with a shape parameter in the range of 0.7–0.9 from room temperature up to 120 °C. The average leakage per failure site is only weakly temperature dependent. The stress-induced structural degradation at the leakage sites exhibits a temperature dependence in the surface morphology, which is consistent with a surface defect generation process involving temperature-associated changes in the breakdown sites

  13. Yolk-albumen testosterone in a lizard with temperature-dependent sex determination: relation with development.

    Science.gov (United States)

    Huang, Victoria; Bowden, Rachel M; Crews, David

    2013-06-01

    The leopard gecko (Eublepharis macularius) exhibits temperature-dependent sex determination as well as temperature-influenced polymorphisms. Research suggests that in oviparous reptiles with temperature-dependent sex determination, steroid hormones in the yolk might influence sex determination and sexual differentiation. From captive leopard geckos that were all from the same incubation temperature regime, we gathered freshly laid eggs, incubated them at one of two female-biased incubation temperatures (26 or 34°C), and measured testosterone content in the yolk-albumen at early or late development. No differences in the concentration of testosterone were detected in eggs from different incubation temperatures. We report testosterone concentrations in the yolk-albumen were higher in eggs of late development than early development at 26°C incubation temperatures, a finding opposite that reported in other TSD reptiles studied to date. Copyright © 2013. Published by Elsevier Inc.

  14. Temperature dependence of the Rashba and Dresselhaus spin–orbit interactions in GaAs wells

    International Nuclear Information System (INIS)

    Wang, W.; Fu, J.Y.

    2016-01-01

    We have recently shown [Fu and Egues, Phys. Rev. B 91 (2015) 075408] unusual properties of the spin–orbit (SO) interaction in relatively wide quantum wells, e.g., the second subband Rashba term can vanish even in asymmetric configurations. Here we report our theoretical investigation on the temperature dependence of Rashba and Dresselhaus SO interactions in GaAs both relatively narrow and wide wells, having the electron occupancy of one and two subbands, respectively. We consider all relevant intra- and intersubband SO terms. We find that the variation of intrasubband couplings as temperatures range from 0.3 to 300 K could attain, ∼meV Å, the order of usual magnitudes for SO terms in GaAs wells. Moreover, we observe distinct behaviors of the SO interaction of the two subbands, as functions of temperature. On the other band, we find that the intersubband SO terms have a relatively weak temperature dependence.

  15. Temperature dependence of the Rashba and Dresselhaus spin–orbit interactions in GaAs wells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W. [Department of Physics, Jining University, 273155 Qufu, Shandong (China); Fu, J.Y., E-mail: jiyongfu78@gmail.com [Department of Physics, Qufu Normal University, 273165 Qufu, Shandong (China); Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, SP (Brazil); Departamento de Física, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil)

    2016-02-01

    We have recently shown [Fu and Egues, Phys. Rev. B 91 (2015) 075408] unusual properties of the spin–orbit (SO) interaction in relatively wide quantum wells, e.g., the second subband Rashba term can vanish even in asymmetric configurations. Here we report our theoretical investigation on the temperature dependence of Rashba and Dresselhaus SO interactions in GaAs both relatively narrow and wide wells, having the electron occupancy of one and two subbands, respectively. We consider all relevant intra- and intersubband SO terms. We find that the variation of intrasubband couplings as temperatures range from 0.3 to 300 K could attain, ∼meV Å, the order of usual magnitudes for SO terms in GaAs wells. Moreover, we observe distinct behaviors of the SO interaction of the two subbands, as functions of temperature. On the other band, we find that the intersubband SO terms have a relatively weak temperature dependence.

  16. Calculated temperature dependence of elastic constants and phonon dispersion of hcp and bcc beryllium

    Science.gov (United States)

    Hahn, Steven; Arapan, Sergiu; Harmon, Bruce; Eriksson, Olle

    2011-03-01

    Conventional first principle methods for calculating lattice dynamics are unable to calculate high temperature thermophysical properties of materials containing modes that are entropically stabilized. In this presentation we use a relatively new approach called self-consistent ab initio lattice dynamics (SCAILD) to study the hcp to bcc transition (1530 K) in beryllium. The SCAILD method goes beyond the harmonic approximation to include phonon-phonon interactions and produces a temperature-dependent phonon dispersion. In the high temperature bcc structure, phonon-phonon interactions dynamically stabilize the N-point phonon. Fits to the calculated phonon dispersion were used to determine the temperature dependence of the elastic constants in the hcp and bcc phases. Work at the Ames Laboratory was supported by the Department of Energy-Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

  17. Specific features of the temperature dependence of the exciton absorption integral in CdS crystals

    International Nuclear Information System (INIS)

    Novikov, A.B.; Solov'ev, L.E.; Talalaev, V.G.

    1986-01-01

    Cadmium sulfide crystals 0.4-2 μm thick in the 4.2-120 K temperature range are investigated experimentally. The shape of the first exciton absorption line in CdS and dependence of integral exciton absorption factor (IEAF) on the quenching constant j are calculated. Rapid growth of the absorption factor in the maximum of the absorption line and decrease of halfwidth of the factor are shown to take place with j increase. The calculation has disclosed that the Bouguer law is observed excluding negligible IEAF oscillations at variation of crystal thickness. Non-monotonous temperature dependence of IEAF is disclosed in some investigated samples; it, obviously, testifies to non-monotonous temperature dependence of j. Depolarization of the absorption line of high-energy exciton states with n=2 and n=3 is discovered in some samples for the first time

  18. Temperature dependence of positron lifetime in ordered porous silica (SBA-3)

    International Nuclear Information System (INIS)

    Kunishige, S.; Koshimizu, M.; Asai, K.

    2009-01-01

    The temperature dependence of positron lifetime in uniform mesopores was analyzed. We used SBA-3 as the sample material, which possesses an ordered porous structure with uniform cylindrical mesopores. The positron lifetime corresponding to the annihilation in the mesopores increased gradually with a decrease in temperature down to 100 K, and its relative intensity also increased concomitantly. This result was attributed to the lower probability of the escape of the ortho-positronium (o-Ps) from the mesopores into the intergrain space at lower temperatures. An anomalous and sudden increase in the lifetime was observed at around 100 K; this result was in agreement with an increase in the positron lifetime reported in a previous study. It was revealed that the increase in the lifetime is very steep in cases of uniform mesopores, suggesting that the temperature dependence is influenced by the pore size.

  19. Development of a temperature-dependent cyclic plasticity constitutive model for SUS304 steel

    International Nuclear Information System (INIS)

    Takahashi, Yukio

    1990-01-01

    Development of an accurate inelastic constitutive model is required to improve the accuracy of inelastic analysis for structural components used in the inelastic region. Based on two fundamental assumptions derived from physical interpretation of temperature dependency of the plastic deformation behavior of type 304 stainless steel, a temperature-dependent cyclic plastic constitutive model is constructed here. Particular emphasis is placed on the modeling of enhanced hardening caused by the dynamic strain aging effect observed in some temperature regimes. Constants and functions involved in the model are determined based on the deformation characteristics observed in the low-cycle fatigue tests conducted at room temperature through 600degC. Several comparisons of model predictions with experimental data show the effectiveness of the present model in non-isothermal condition as well as in isothermal condition between room temperature and 600degC. (author)

  20. Temperature dependence of Raman scattering in β-(AlGa2O3 thin films

    Directory of Open Access Journals (Sweden)

    Xu Wang

    2016-01-01

    Full Text Available We report a detailed investigation on temperature-dependent Raman scattering of β-(AlGa2O3 thin films with different Al content (0-0.72 under the temperature range of 77-300 K. The temperature-dependent Raman shifts and linewidths of the phonon modes were obtained by employing Lorentz fitting. The linewidths broadening of phonon modes with the temperature can be well explained by a model involving the effects of thermal expansion, lattice-mismatch-induced strain, and decay of optical phonon into two and three phonons. It is clearly demonstrated dependence of the linewidths and decay process on the Al content in β-(AlGa2O3 thin films, which can provide an experimental basis for realization of (AlGa2O3-based optoelectronic device applications.

  1. Temperature dependence of magnetic anisotropies in ultrathin Fe film on vicinal Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong-Sheng; He, Wei; Ye, Jun; Hu, Bo; Tang, Jin; Zhang, Xiang-Qun [State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Cheng, Zhao-Hua, E-mail: zhcheng@aphy.iphy.ac.cn [State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190 (China)

    2017-05-01

    The temperature dependence of magnetic anisotropy of ultrathin Fe film with different thickness epitaxially grown on vicinal Si(111) substrate has been quantitatively investigated using the anisotropic magnetoresistance(AMR) measurements. Due to the effect of the vicinal substrate, the magnetic anisotropy is the superposition of a four-fold, a two-fold and a weakly six-fold contribution. It is found that the temperature dependence of the first-order magnetocrystalline anisotropies coefficient follows power laws of the reduced magnetization m(T)(=M(T)/M(0)) being consistent with the Callen and Callen's theory. However the temperature dependence of uniaxial magnetic anisotropy (UMA) shows novel behavior that decreases roughly as a function of temperature with different power law for samples with different thickness. We also found that the six-fold magnetocrystalline anisotropy is almost invariable over a wide temperature range. Possible mechanisms leading to the different exponents are discussed.

  2. Defects level evaluation of LiTiZn ferrite ceramics using temperature dependence of initial permeability

    Science.gov (United States)

    Malyshev, A. V.; Petrova, A. B.; Sokolovskiy, A. N.; Surzhikov, A. P.

    2018-06-01

    The method for evaluating the integral defects level and chemical homogeneity of ferrite ceramics based on temperature dependence analysis of initial permeability is suggested. A phenomenological expression for the description of such dependence was suggested and an interpretation of its main parameters was given. It was shown, that the main criterion of the integral defects level of ferrite ceramics is relation of two parameters correlating with elastic stress value in a material. An indicator of structural perfection can be a maximum value of initial permeability close to Curie point as well. The temperature dependences of initial permeability have analyzed for samples sintered in laboratory conditions and for the ferrite industrial product. The proposed method allows controlling integral defects level of the soft ferrite products and has high sensitivity compare to typical X-ray methods.

  3. Natural convection heat transfer of fluid with temperature-dependent specific heat

    International Nuclear Information System (INIS)

    Tanaka, Amane; Kubo, Shinji; Akino, Norio

    1998-01-01

    The present study investigates natural convection from a heated vertical plate of fluid with temperature-dependent specific heat, which is introduced as a model of microencapsulated phase change material slurries (MCPCM slurries). The temperature dependence of specific heat is represented by Gauss function with three physical parameters (peak temperature, width of phase change temperature and latent heat). Boundary layer equations are solved numerically, and the velocity and temperature fields of the flow are obtained. The relation between the heat transfer coefficients and the physical parameters of specific heat is discussed. The results show that the velocities and temperatures are smaller, and the heat transfer coefficients are larger comparing with those of the fluid with constant specific heat. (author)

  4. Parasitic bipolar amplification in a single event transient and its temperature dependence

    International Nuclear Information System (INIS)

    Liu Zheng; Chen Shu-Ming; Chen Jian-Jun; Qin Jun-Rui; Liu Rong-Rong

    2012-01-01

    Using three-dimensional technology computer-aided design (TCAD) simulation, parasitic bipolar amplification in a single event transient (SET) current of a single transistor and its temperature dependence are studied. We quantify the contributions of different current components in a SET current pulse, and it is found that the proportion of parasitic bipolar amplification in total collected charge is about 30% in both 130-nm and 90-nm technologies. The temperature dependence of parasitic bipolar amplification and the mechanism of the SET pulse are also investigated and quantified. The results show that the proportion of charge induced by parasitic bipolar increases with rising temperature, which illustrates that the parasitic bipolar amplification plays an important role in the charge collection of a single transistor

  5. Temperature dependent transport of two dimensional electrons in the integral quantum Hall regime

    International Nuclear Information System (INIS)

    Wi, H.P.

    1986-01-01

    This thesis is concerned with the temperature dependent electronic transport properties of a two dimensional electron gas subject to background potential fluctuations and a perpendicular magnetic field. The author carried out an extensive temperature dependent study of the transport coefficients, in the region of an integral quantum plateau, in an In/sub x/Ga/sub 1-x/As/InP heterostructure for 4.2K 10 cm -2 meV -1 ) even at the middle between two Landau levels, which is unexpected from model calculations based on short ranged randomness. In addition, the different T dependent behavior of rho/sub xx/ between the states in the tails and those near the center of a Landau level, indicates the existence of different electron states in a Landau level. Additionally, the author reports T-dependent transport measurements in the transition region between two quantum plateaus in several different materials

  6. Memory effects, two color percolation, and the temperature dependence of Mott variable-range hopping

    Science.gov (United States)

    Agam, Oded; Aleiner, Igor L.

    2014-06-01

    There are three basic processes that determine hopping transport: (a) hopping between normally empty sites (i.e., having exponentially small occupation numbers at equilibrium), (b) hopping between normally occupied sites, and (c) transitions between normally occupied and unoccupied sites. In conventional theories all these processes are considered Markovian and the correlations of occupation numbers of different sites are believed to be small (i.e., not exponential in temperature). We show that, contrary to this belief, memory effects suppress the processes of type (c) and manifest themselves in a subleading exponential temperature dependence of the variable-range hopping conductivity. This temperature dependence originates from the property that sites of type (a) and (b) form two independent resistor networks that are weakly coupled to each other by processes of type (c). This leads to a two-color percolation problem which we solve in the critical region.

  7. EXACT SOLUTION FOR TEMPERATURE-DEPENDENT BUCKLING ANALYSIS OF FG-CNT-REINFORCED MINDLIN PLATES

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Mousavi

    2016-03-01

    Full Text Available This research deals with the buckling analysis of nanocomposite polymeric temperature-dependent plates reinforced by single-walled carbon nanotubes (SWCNTs. For the carbon-nanotube reinforced composite (CNTRC plate, uniform distribution (UD and three types of functionally graded (FG distribution patterns of SWCNT reinforcements are assumed. The material properties of FG-CNTRC plate are graded in the thickness direction and estimated based on the rule of mixture. The CNTRC is located in a elastic medium which is simulated with temperature-dependent Pasternak medium. Based on orthotropic Mindlin plate theory, the governing equations are derived using Hamilton’s principle and solved by Navier method. The influences of the volume fractions of carbon nanotubes, elastic medium, temperature and distribution type of CNTs are considered on the buckling of the plate. Results indicate that CNT distribution close to top and bottom are more efficient than those distributed nearby the mid-plane for increasing the stiffness of plates.

  8. Preisach modeling of temperature-dependent ferroelectric response of piezoceramics at sub-switching regime

    Science.gov (United States)

    Ochoa, Diego Alejandro; García, Jose Eduardo

    2016-04-01

    The Preisach model is a classical method for describing nonlinear behavior in hysteretic systems. According to this model, a hysteretic system contains a collection of simple bistable units which are characterized by an internal field and a coercive field. This set of bistable units exhibits a statistical distribution that depends on these fields as parameters. Thus, nonlinear response depends on the specific distribution function associated with the material. This model is satisfactorily used in this work to describe the temperature-dependent ferroelectric response in PZT- and KNN-based piezoceramics. A distribution function expanded in Maclaurin series considering only the first terms in the internal field and the coercive field is proposed. Changes in coefficient relations of a single distribution function allow us to explain the complex temperature dependence of hard piezoceramic behavior. A similar analysis based on the same form of the distribution function shows that the KNL-NTS properties soften around its orthorhombic to tetragonal phase transition.

  9. Temperature dependence of the magnetic excitation spectrum of Dy2Fe14B

    International Nuclear Information System (INIS)

    Loewenhaupt, M.; Fabi, P.; Sosnowska, I.; Frick, B.; Eccleston, R.

    1995-01-01

    We present inelastic magnetic neutron scattering spectra of polycrystalline Dy 2 Fe 14 B measured between 2 and 650 K employing different time-of-flight spectrometers. At the lowest temperatures we can identify in the magnetic excitation spectra the following features: (i) a dominant line at Δ=12 meV with a shoulder at 11.1 meV, and (ii) two weak lines at 3.8 and 5.5 meV. The temperature dependence of the average position Δ of the dominant line follows roughly the temperature dependence of the spontaneous magnetization of Y 2 Fe 14 B indicating that the energy of this mode is substantially fixed by the molecular fields of the surrounding Fe moments. Slight deviations, however, indicate that the Dy level spacing is not equidistant due to crystal field effects. ((orig.))

  10. Temperature-dependent surface density of alkylthiol monolayers on gold nanocrystals

    Science.gov (United States)

    Liu, Xuepeng; Lu, Pin; Zhai, Hua; Wu, Yucheng

    2018-03-01

    Atomistic molecular dynamics (MD) simulations are performed to study the surface density of passivating monolayers of alkylthiol chains on gold nanocrystals at temperatures ranging from 1 to 800 K. The results show that the surface density of alkylthiol monolayer reaches a maximum value at near room temperature (200-300 K), while significantly decreases with increasing temperature in the higher temperature region (> 300 {{K}}), and slightly decreases with decreasing temperature at low temperature (< 200 {{K}}). We find that the temperature dependence of surface ligand density in the higher temperature region is attributed to the substantial ligand desorption induced by the thermal fluctuation, while that at low temperature results from the reduction in entropy caused by the change in the ordering of passivating monolayer. These results are expected helpful to understand the temperature-dependent surface coverage of gold nanocrystals.

  11. Temperature Dependence of the Energy Band Diagram of AlGaN/GaN Heterostructure

    Directory of Open Access Journals (Sweden)

    Yanli Liu

    2018-01-01

    Full Text Available Temperature dependence of the energy band diagram of AlGaN/GaN heterostructure was investigated by theoretical calculation and experiment. Through solving Schrodinger and Poisson equations self-consistently by using the Silvaco Atlas software, the energy band diagram with varying temperature was calculated. The results indicate that the conduction band offset of AlGaN/GaN heterostructure decreases with increasing temperature in the range of 7 K to 200 K, which means that the depth of quantum well at AlGaN/GaN interface becomes shallower and the confinement of that on two-dimensional electron gas reduces. The theoretical calculation results are verified by the investigation of temperature dependent photoluminescence of AlGaN/GaN heterostructure. This work provides important theoretical and experimental basis for the performance degradation of AlGaN/GaN HEMT with increasing temperature.

  12. Unusual temperature dependence of the positron lifetime in a polymer of intrinsic microporosity

    International Nuclear Information System (INIS)

    Lima de Miranda, Rodrigo; Kruse, Jan; Raetzke, Klaus; Faupel, Franz; Fritsch, Detlev; Abetz, Volker; Budd, Peter M.; Selbie, James D.; McKeown, Neil B.; Ghanem, Bader S.

    2007-01-01

    The performance of polymeric membranes for gas separation is mainly determined by the free volume. Polymers of intrinsic microporosity are interesting due to the high abundance of accessible free volume. We performed measurements of the temperature dependence of the positron lifetime, generally accepted for investigation of free volume, in two polymers of intrinsic microporosity (PIM-1 and PIM-7) in the range from 143 to 523 K. The mean value of the free volume calculated from the ortho-positronium lifetime is in the range of typical values for high free volume polymers. However, the temperature dependence of the local free volume is non-monotonous in contrast to the macroscopic thermal expansion. The explanation is linked to the spirocenters in the polymer. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Temperature dependence of stress in CVD diamond films studied by Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Dychalska Anna

    2015-09-01

    Full Text Available Evolution of residual stress and its components with increasing temperature in chemical vapor deposited (CVD diamond films has a crucial impact on their high temperature applications. In this work we investigated temperature dependence of stress in CVD diamond film deposited on Si(100 substrate in the temperature range of 30 °C to 480 °C by Raman mapping measurement. Raman shift of the characteristic diamond band peaked at 1332 cm-1 was studied to evaluate the residual stress distribution at the diamond surface. A new approach was applied to calculate thermal stress evolution with increasing tempera­ture by using two commonly known equations. Comparison of the residts obtained from the two methods was presented. The intrinsic stress component was calculated from the difference between average values of residual and thermal stress and then its temperature dependence was discussed.

  14. Temperature dependence of the electrical resistivity of amorphous Co80-xErxB20 alloys

    International Nuclear Information System (INIS)

    Touraghe, O.; Khatami, M.; Menny, A.; Lassri, H.; Nouneh, K.

    2008-01-01

    The temperature dependence of the electrical resistivity of amorphous Co 80-x Er x B 20 alloys with x=0, 3.9, 7.5 and 8.6 prepared by melt spinning in pure argon atmosphere was studied. All amorphous alloys investigated here are found to exhibit a resistivity minimum at low temperature. The electrical resistivity exhibits logarithmic temperature dependence below the temperature of resistivity minimum T min . In addition, the resistivity shows quadratic temperature behavior in the interval T min < T<77 K. At high temperature, the electrical resistivity was discussed by the extended Ziman theory. For the whole series of alloys, the composition dependence of the temperature coefficient of electrical resistivity α shows a change in structural short range occurring in the composition range 8-9 at%

  15. The temperature dependence of atomic incorporation characteristics in growing GaInNAs films

    International Nuclear Information System (INIS)

    Li, Jingling; Gao, Fangliang; Wen, Lei; Zhou, Shizhong; Zhang, Shuguang; Li, Guoqiang

    2015-01-01

    We have systematically studied the temperature dependence of incorporation characteristics of nitrogen (N) and indium (In) in growing GaInNAs films. With the implementation of Monte-Carlo simulation, the low N adsorption energy (−0.10 eV) is demonstrated. To understand the atomic incorporation mechanism, temperature dependence of interactions between Group-III and V elements are subsequently discussed. We find that the In incorporation behaviors rather than that of N are more sensitive to the T g , which can be experimentally verified by exploring the compositional modulation and structural changes of the GaInNAs films by means of high-resolution X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, and secondary ion mass spectroscopy

  16. Temperature-dependent piezoresistivity in an MWCNT/epoxy nanocomposite temperature sensor with ultrahigh performance

    International Nuclear Information System (INIS)

    Alamusi; Li, Yuan; Hu, Ning; Wu, Liangke; Liu, Yaolu; Ning, Huiming; Li, Jinhua; Surina; Yuan, Weifeng; Chang, Christiana; Atobe, Satoshi; Fukunaga, Hisao

    2013-01-01

    A temperature sensor was fabricated from a polymer nanocomposite with multi-walled carbon nanotube (MWCNT) as nanofiller (i.e., MWCNT/epoxy). The electrical resistance and temperature coefficient of resistance (TCR) of the temperature sensor were characterized experimentally. The effects of temperature (within the range 333–373 K) and MWCNT content (within the range 1–5 wt%) were investigated thoroughly. It was found that the resistance increases with increasing temperature and decreasing MWCNT content. However, the resistance change ratio related to the TCR increases with increasing temperature and MWCNT content. The highest value of TCR (0.021 K −1 ), which was observed in the case of 5 wt% MWCNT, is much higher than those of traditional metals and MWCNT-based temperature sensors. Moreover, the corresponding numerical simulation—conducted to explain the above temperature-dependent piezoresistivity of the nanocomposite temperature sensor—indicated the key role of a temperature-dependent tunneling effect. (paper)

  17. Temperature dependence of conductivity in high mobility MIS structures on a base of (001) silicon

    International Nuclear Information System (INIS)

    Vyrodov, E.A.; Dolgopolov, V.T.; Dorozhkin, C.I.; Zhitenev, N.B.

    1988-01-01

    Measurements of the temperature dependence of the conductivity of two-dimensional electrons in silicon MIS structures were carried out. It is shown that the observed dependence is well described by the equation σ(T) = σ(0)(1-Q(kT var-epsilon F )-P(kT/var-epsilon F )3/2 + O[(kT/var-epsilon F ) 2 ]). The variation of the coefficient Q with the density N S of the two-dimensional electrons is determined, and it is shown that the observed trend of the Q(s) curve is described by consideration of the temperature dependence of the dielectric function of a two-dimensional electron gas

  18. Probing Temperature-Dependent Recombination Kinetics in Polymer:Fullerene Solar Cells by Electric Noise Spectroscopy

    Directory of Open Access Journals (Sweden)

    Giovanni Landi

    2017-09-01

    Full Text Available The influence of solvent additives on the temperature behavior of both charge carrier transport and recombination kinetics in bulk heterojunction solar cells has been investigated by electric noise spectroscopy. The observed differences in charge carrier lifetime and mobility are attributed to a different film ordering and donor-acceptor phase segregation in the blend. The measured temperature dependence indicates that bimolecular recombination is the dominant loss mechanism in the active layer, affecting the device performance. Blend devices prepared with a high-boiling-point solvent additive show a decreased recombination rate at the donor-acceptor interface as compared to the ones prepared with the reference solvent. A clear correlation between the device performance and the morphological properties is discussed in terms of the temperature dependence of the mobility-lifetime product.

  19. An improved stochastic algorithm for temperature-dependent homogeneous gas phase reactions

    CERN Document Server

    Kraft, M

    2003-01-01

    We propose an improved stochastic algorithm for temperature-dependent homogeneous gas phase reactions. By combining forward and reverse reaction rates, a significant gain in computational efficiency is achieved. Two modifications of modelling the temperature dependence (with and without conservation of enthalpy) are introduced and studied quantitatively. The algorithm is tested for the combustion of n-heptane, which is a reference fuel component for internal combustion engines. The convergence of the algorithm is studied by a series of numerical experiments and the computational cost of the stochastic algorithm is compared with the DAE code DASSL. If less accuracy is needed the stochastic algorithm is faster on short simulation time intervals. The new stochastic algorithm is significantly faster than the original direct simulation algorithm in all cases considered.

  20. Temperature-dependent interaction potential between NF3 molecules and thermophysical properties of gaseous NF3

    International Nuclear Information System (INIS)

    Damyanova, M; Balabanova, E; Hohm, U

    2014-01-01

    A temperature-dependent effective intermolecular interaction potential is applied to describe the interaction between two nitrogen fluoride (NF 3 ) molecules in gas phase. To this end, a spherically-symmetric (n-6) Lennard-Jones temperature-dependent potential (LJTDP) is used. The (n-6) LJTDP takes into account the influence of vibrational excitation of the molecules on the potential parameters, namely, the equilibrium distance r m and the potential well depth ε. The potential parameters at T = 0 K were obtained from the very small amount of existing thermophysical equilibrium and transport properties of low-density NF 3 gas. Fitting formulae are tabulated for a fast and reliable prediction of the thermophysical properties and potential parameters in the temperature range between 200 K and 1200 K. A comparison is also presented between our estimates for some thermophysical properties of the NF 3 gas with the available experimental and calculated data.

  1. Temperature dependence and hysteresis of the initial permeability of the 50%Ni - 50%Fe alloy

    International Nuclear Information System (INIS)

    Kekalo, I.B.; Stolyarov, V.L.; Patsionov, V.A.

    1979-01-01

    Studied has been a temperature dependence of the initial permeability of the 50% Ni - 50% Fe alloy after primary and secondary recrystallization and effect of thermomagnetic treatment upon the dependence. For all the alloys with the structure of primary recrystallization a monotonous increase of initial permeability with temperature and the presence of slight temperature hysteresis are typical. Thermomagnetic treatment, not affecting considerably the temperature dependence of permeability for all the primarily recrystallized alloys, changes to a great extent the character of the dependence in the secondary recrystallized alloys. For 20-200-20 deg C temperature cycle of the alloys with secondary recrystallized structure are characterized after thermomagnetic treatment by the presence of gigantic hysteresis of initial permeability and a maximum on the heating branch of the curve in the vicinity of 130 deg C which are accounted for by peculiarities of temperature hysteresis of domain structure in the given alloy

  2. Temperature dependence of magnetically dead layers in ferromagnetic thin-films

    Directory of Open Access Journals (Sweden)

    M. Tokaç

    2017-11-01

    Full Text Available Polarized neutron reflectometry has been used to study interface magnetism and magnetic dead layers in model amorphous CoFeB:Ta alloy thin-film multilayers with Curie temperatures tuned to be below room-temperature. This allows temperature dependent variations in the effective magnetic thickness of the film to be determined at temperatures that are a significant fraction of the Curie temperature, which cannot be achieved in the material systems used for spintronic devices. In addition to variation in the effective magnetic thickness due to compositional grading at the interface with the tantalum capping layer, the key finding is that at the interface between ferromagnetic film and GaAs(001 substrate local interfacial alloying creates an additional magnetic dead-layer. The thickness of this magnetic dead-layer is temperature dependent, which may have significant implications for elevated-temperature operation of hybrid ferromagnetic metal-semiconductor spintronic devices.

  3. Temperature Dependence of Faraday Effect-Induced Bias Error in a Fiber Optic Gyroscope.

    Science.gov (United States)

    Li, Xuyou; Liu, Pan; Guang, Xingxing; Xu, Zhenlong; Guan, Lianwu; Li, Guangchun

    2017-09-07

    Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environments, such as magnetic field and temperature field variation, is necessary for its practical applications. This paper presents an investigation of Faraday effect-induced bias error of IFOG under varying temperature. Jones matrix method is utilized to formulize the temperature dependence of Faraday effect-induced bias error. Theoretical results show that the Faraday effect-induced bias error changes with the temperature in the non-skeleton polarization maintaining (PM) fiber coil. This phenomenon is caused by the temperature dependence of linear birefringence and Verdet constant of PM fiber. Particularly, Faraday effect-induced bias errors of two polarizations always have opposite signs that can be compensated optically regardless of the changes of the temperature. Two experiments with a 1000 m non-skeleton PM fiber coil are performed, and the experimental results support these theoretical predictions. This study is promising for improving the bias stability of IFOG.

  4. Temperature dependences of photoconductivity of CdHgTe crystals with photoactive inclusions

    International Nuclear Information System (INIS)

    Vlasenko, A.I.; Vlasenko, Z.K.

    1999-01-01

    Temperature dependences of life time τ and spectral characteristics of photoconductivity for Cd x Hg 1-x Te crystals (x = 0.2) with photoactive inclusions are investigated. It is shown that the N-type character of effective lifetime temperature dependences in nonhomogeneous crystals, in particular, its sharp temperature activation in the region of transition from the impurity to the intrinsic conductivity is determined by not the Shockley-Read mechanism, but by the interband impact mechanism with changing effective geometrical sizes of recombination active regions under temperature increase. Within the frames of this model the smoothing of the non-monotone character of the photoconductivity spectral characteristics in the region of fundamental absorption under the heating is explained. The calculation results that are in qualitative agreement with the experimental data are presented [ru

  5. Optical spectral weight anomalies and strong correlation

    International Nuclear Information System (INIS)

    Toschi, A.; Capone, M.; Ortolani, M.; Calvani, P.; Lupi, S.; Castellani, C.

    2007-01-01

    The anomalous behavior observed in the optical spectral weight (W) of the cuprates provides valuable information about the physics of these compounds. Both the doping and the temperature dependences of W are hardly explained through conventional estimates based on the f-sum rule. By computing the optical conductivity of the doped Hubbard model with the Dynamical Mean Field Theory, we point out that the strong correlation plays a key role in determining the basic features of the observed anomalies: the proximity to a Mott insulating phase accounts simultaneously for the strong temperature dependence of W and for its zero temperature value

  6. Brominated flame retardants in the urban atmosphere of Northeast China: Concentrations, temperature dependence and gas-particle partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Hong; Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Ma, Wan-Li, E-mail: mawanli002@163.com; Li, Yi-Fan, E-mail: ijrc_pts_paper@yahoo.com

    2014-09-01

    57 pairs of air samples (gas and particle phases) were collected using a high volume air sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total concentrations of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m{sup 3} and 180 pg/m{sup 3}, respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the gas phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the gas–particle partitioning coefficients (logK{sub p}) for most low molecular weight BFRs were highly temperature dependent as well. Gas–particle partitioning coefficients (logK{sub p}) also correlated with the sub-cooled liquid vapor pressure (logP{sub L}{sup o}). Our results indicated that absorption into organic matter is the main control mechanism for the gas–particle partitioning of atmospheric PBDEs. - Highlights: • Both PBDEs and alternative BFRs were analyzed in the atmosphere of Northeast China. • Partial pressure of BFRs was significantly correlated with the ambient temperature. • A strong temperature dependence of gas-particle partitioning was found. • Absorption into organic matter was the control mechanism for G-P partitioning.

  7. In-situ high temperature irradiation setup for temperature dependent structural studies of materials under swift heavy ion irradiation

    International Nuclear Information System (INIS)

    Kulriya, P.K.; Kumari, Renu; Kumar, Rajesh; Grover, V.; Shukla, R.; Tyagi, A.K.; Avasthi, D.K.

    2015-01-01

    An in-situ high temperature (1000 K) setup is designed and installed in the materials science beam line of superconducting linear accelerator at the Inter-University Accelerator Centre (IUAC) for temperature dependent ion irradiation studies on the materials exposed with swift heavy ion (SHI) irradiation. The Gd 2 Ti 2 O 7 pyrochlore is irradiated using 120 MeV Au ion at 1000 K using the high temperature irradiation facility and characterized by ex-situ X-ray diffraction (XRD). Another set of Gd 2 Ti 2 O 7 samples are irradiated with the same ion beam parameter at 300 K and simultaneously characterized using in-situ XRD available in same beam line. The XRD studies along with the Raman spectroscopic investigations reveal that the structural modification induced by the ion irradiation is strongly dependent on the temperature of the sample. The Gd 2 Ti 2 O 7 is readily amorphized at an ion fluence 6 × 10 12 ions/cm 2 on irradiation at 300 K, whereas it is transformed to a radiation-resistant anion-deficient fluorite structure on high temperature irradiation, that amorphized at ion fluence higher than 1 × 10 13 ions/cm 2 . The temperature dependent ion irradiation studies showed that the ion fluence required to cause amorphization at 1000 K irradiation is significantly higher than that required at room temperature irradiation. In addition to testing the efficiency of the in-situ high temperature irradiation facility, the present study establishes that the radiation stability of the pyrochlore is enhanced at higher temperatures

  8. Temperature-dependent respiration-growth relations in ancestral maize cultivars

    Science.gov (United States)

    Bruce N. Smith; Jillian L. Walker; Rebekka L. Stone; Angela R. Jones; Lee D. Hansen

    2001-01-01

    Shoots from 4- to 6-day old seedlings of seven ancestral or old cultivars of Zea mays L. were placed in a calorimeter. Dark metabolic heat rate (q) and CO2 production rate (RCO2) were measured at nine temperatures (5, 10, 15, 20, 25, 30, 35, 40, and 45 °C). Temperature dependencies of q and RCO2 were used to model response of both growth and substrate carbon conversion...

  9. On the temperature dependence of spin pumping in ferromagnet–topological insulator–ferromagnet spin valves

    Directory of Open Access Journals (Sweden)

    A.A. Baker

    Full Text Available Topological insulators (TIs have a large potential for spintronic devices owing to their spin-polarized, counter-propagating surface states. Recently, we have investigated spin pumping in a ferromagnet–TI–ferromagnet structure at room temperature. Here, we present the temperature-dependent measurement of spin pumping down to 10 K, which shows no variation with temperature. Keywords: Topological insulator, Spin pumping, Spintronics, Ferromagnetic resonance

  10. Inverse temperature dependence of reverse gate leakage current in AlGaN/GaN HEMT

    International Nuclear Information System (INIS)

    Kaushik, J K; Balakrishnan, V R; Muralidharan, R; Panwar, B S

    2013-01-01

    The experimentally observed inverse temperature dependence of the reverse gate leakage current in AlGaN/GaN HEMT is explained using a virtual gate trap-assisted tunneling model. The virtual gate is formed due to the capture of electrons by surface states in the vicinity of actual gate. The increase and decrease in the length of the virtual gate with temperature due to trap kinetics are used to explain this unusual effect. The simulation results have been validated experimentally. (paper)

  11. The temperature dependence of the isothermal bulk modulus at 1 bar pressure

    International Nuclear Information System (INIS)

    Garai, J.; Laugier, A.

    2007-01-01

    It is well established that the product of the volume coefficient of thermal expansion and the bulk modulus is nearly constant at temperatures higher than the Debye temperature. Using this approximation allows predicting the values of the bulk modulus. The derived analytical solution for the temperature dependence of the isothermal bulk modulus has been applied to ten substances. The good correlations to the experiments indicate that the expression may be useful for substances for which bulk modulus data are lacking

  12. Identification of microscopic domain wall motion from temperature dependence of nonlinear dielectric response.

    Czech Academy of Sciences Publication Activity Database

    Mokrý, Pavel; Sluka, T.

    2017-01-01

    Roč. 110, č. 16 (2017), č. článku 162906. ISSN 0003-6951 R&D Projects: GA ČR(CZ) GA14-32228S Institutional support: RVO:61389021 Keywords : microscopic domain wall * electric fields * temperature dependence Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Electrical and electronic engineering Impact factor: 3.411, year: 2016 http://dx.doi.org/10.1063/1.4981874

  13. Temperature dependence of the current to sustain a normal hotspot in superconducting microbridges

    International Nuclear Information System (INIS)

    Yamaguchi, Y.; Ishii, C.

    1981-01-01

    A modification of the boundary condition to determine the SN boundary in the hotspot model of superconducting microbridges is proposed and successfully applied to the interpretation of recent measurements of the hotspot-sustaining current by Mizuno and Aomine. It is shown that suppression of the order parameter due to the applied current gives rise to an additional temperature dependence of the hotspot-sustaining current in the extreme vicinity of the transition temperature. (orig.)

  14. Temperature dependence Infrared and Raman studies of III-V/II-VI core-shell nanostructures

    Science.gov (United States)

    Manciu, Felicia S.; McCombe, Bruce D.; Lucey, Derrick

    2005-03-01

    The temperature dependence (8 K InP/ZnS sample. Raman scattering (457.9 nm excitation) features were determined without polarization selection in the backscattering geometry. Interesting T-dependent resonant Raman effect of the surface optical phonon modes has been discovered in InP/ZnSe sample. Reasonable agreement is obtained between the Raman and FIR results, as well as with theoretical calculations.

  15. Temperature dependence of CIE-x,y color coordinates in YAG:Ce single crystal phosphor

    Czech Academy of Sciences Publication Activity Database

    Rejman, M.; Babin, Vladimir; Kučerková, Romana; Nikl, Martin

    2017-01-01

    Roč. 187, Jul (2017), s. 20-25 ISSN 0022-2313 R&D Projects: GA TA ČR TA04010135 Institutional support: RVO:68378271 Keywords : YAG:Ce * single-crystal * simulation * energy level lifetime * white LED * CIE * temperature dependence Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.686, year: 2016

  16. Temperature dependence of the hydrogen-broadening coefficient for the nu 9 fundamental of ethane

    Science.gov (United States)

    Halsey, G. W.; Hillman, J. J.; Nadler, Shacher; Jennings, D. E.

    1988-01-01

    Experimental results for the temperature dependence of the H2-broadening coefficient for the nu 9 fundamental of ethane are reported. Measurements were made over the temperature range 95-300 K using a novel low-temperature absorption cell. These spectra were recorded with the Doppler-limited diode laser spectrometer at NASA Goddard. The results are compared with recent measurements and model predictions.

  17. An unusual temperature dependence in the oxidation of oxycarbide layers on uranium

    Science.gov (United States)

    Ellis, Walton P.

    1981-09-01

    An anomalous temperature dependence has been observed for the oxidation kinetics of outermost oxycarbide layers on polycrystalline uranium metal. Normally, oxidation or corrosion reactions are expected to proceed more rapidly as the temperature is elevated. Thus, it came as a surprise when we observed that the removal of the outermost atomic layers of carbon from uranium oxycarbide by O 2 reproducibly proceeds at a much faster rate at 25°C than at 280°C.

  18. An analytical method for determining the temperature dependent moisture diffusivities of pumpkin seeds during drying process

    Energy Technology Data Exchange (ETDEWEB)

    Can, Ahmet [Department of Mechanical Engineering, University of Trakya, 22030 Edirne (Turkey)

    2007-02-15

    This paper presents an analytical method, which determines the moisture diffusion coefficients for the natural and forced convection hot air drying of pumpkin seeds and their temperature dependence. In order to obtain scientific data, the pumpkin seed drying process was investigated under both natural and forced hot air convection regimes. This paper presents the experimental results in which the drying air was heated by solar energy. (author)

  19. Temperature dependence of the 2D′ mode of an isotopically labelledgraphene double layer

    Czech Academy of Sciences Publication Activity Database

    Verhagen, Timotheus; Valeš, Václav; Frank, Otakar; Kalbáč, Martin; Vejpravová, Jana

    2016-01-01

    Roč. 253, č. 12 (2016), 2342-2346 ISSN 0370-1972 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : graphene * isotope labelling * Raman spectroscopy * temperature dependence Subject RIV: BM - Solid Matter Physics ; Magnetism; CG - Electrochemistry (UFCH-W) Impact factor: 1.674, year: 2016

  20. Temperature dependence of exchange anisotropy in monodisperse cobalt nanoparticles with a cobalt oxide shell

    International Nuclear Information System (INIS)

    Spasova, M.; Wiedwald, U.; Farle, M.; Radetic, T.; Dahmen, U.; Hilgendorff, M.; Giersig, M.

    2004-01-01

    Exchange anisotropy was studied by SQUID magnetometry on an array of monodisperse colloidal nanoparticles consisting of a 7-8 nm diameter FCC Co core covered with a 2-2.5 nm thick FCC CoO shell. Temperature-dependent measurements of the exchange bias field show that the exchange anisotropy vanishes when a magnetic field was applied during cooling below 150 K. The suppression of exchange anisotropy is due to uncompensated interfacial antiferromagnetic spins

  1. Temperature dependence of the Al2O3:C response in medical luminescence dosimetry

    DEFF Research Database (Denmark)

    Edmund, Jens Morgenthaler; Andersen, Claus Erik

    2007-01-01

    is not varied. The RL response only depends on the irradiation temperature. We recommend that calibration should be carried out at the same irradiation temperature at which the measurement is performed (i.e. at body temperature for in vivo measurements). The overall change in the integrated OSL and RL signals...... and detection wavelengths. The reported temperature dependence seems to be a general property of Al2O3:C. (C) 2006 Elsevier Ltd. All rights reserved....

  2. Size and temperature dependence of the tensile mechanical properties of zinc blende CdSe nanowires

    International Nuclear Information System (INIS)

    Fu, Bing; Chen, Na; Xie, Yiqun; Ye, Xiang; Gu, Xiao

    2013-01-01

    The effect of size and temperature on the tensile mechanical properties of zinc blende CdSe nanowires is investigated by all atoms molecular dynamic simulation. We found the ultimate tensile strength and Young's modulus will decrease as the temperature and size of the nanowire increase. The size and temperature dependence are mainly attributed to surface effect and thermally elongation effect. High reversibility of tensile behavior will make zinc blende CdSe nanowires suitable for building efficient nanodevices.

  3. Anomalous temperature dependence of the Seebeck coefficient for the substitutionally-disordered hopping conductors

    International Nuclear Information System (INIS)

    Raffaelle, R.P.; Parris, P.E.; Anderson, H.U.; Sparlin, D.M.

    1991-01-01

    Thermoelectric power measurements are presented for the (La,Sr)(Cr,Mn)O 3 series. The nonlinear temperature dependence of the Seebeck coefficient is analyzed in terms of a random distribution of energetically equivalent hopping sites. The limitations of Heikes' formula, which has been traditionally used to calculate small polaron carrier densities in these systems, are discussed. Recent theoretical developments in the interpretation of Seebeck measurements in substitutionally-disordered high-temperature hopping conductors are reviewed

  4. Estimation of the temperature dependent interaction between uncharged point defects in Si

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan); GlobalWafers Japan Co., Ltd., 30 Soya, Hadano, Kanagawa, 257-8566 (Japan); Vanhellemont, Jan [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, Ghent B-9000 (Belgium); Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan)

    2015-01-15

    A method is described to estimate the temperature dependent interaction between two uncharged point defects in Si based on DFT calculations. As an illustration, the formation of the uncharged di-vacancy V{sub 2} is discussed, based on the temperature dependent attractive field between both vacancies. For that purpose, all irreducible configurations of two uncharged vacancies are determined, each with their weight given by the number of equivalent configurations. Using a standard 216-atoms supercell, nineteen irreducible configurations of two vacancies are obtained. The binding energies of all these configurations are calculated. Each vacancy is surrounded by several attractive sites for another vacancy. The obtained temperature dependent of total volume of these attractive sites has a radius that is closely related with the capture radius for the formation of a di-vacancy that is used in continuum theory. The presented methodology can in principle also be applied to estimate the capture radius for pair formation of any type of point defects.

  5. Re-estimating temperature-dependent consumption parameters in bioenergetics models for juvenile Chinook salmon

    Science.gov (United States)

    Plumb, John M.; Moffitt, Christine M.

    2015-01-01

    Researchers have cautioned against the borrowing of consumption and growth parameters from other species and life stages in bioenergetics growth models. In particular, the function that dictates temperature dependence in maximum consumption (Cmax) within the Wisconsin bioenergetics model for Chinook Salmon Oncorhynchus tshawytscha produces estimates that are lower than those measured in published laboratory feeding trials. We used published and unpublished data from laboratory feeding trials with subyearling Chinook Salmon from three stocks (Snake, Nechako, and Big Qualicum rivers) to estimate and adjust the model parameters for temperature dependence in Cmax. The data included growth measures in fish ranging from 1.5 to 7.2 g that were held at temperatures from 14°C to 26°C. Parameters for temperature dependence in Cmax were estimated based on relative differences in food consumption, and bootstrapping techniques were then used to estimate the error about the parameters. We found that at temperatures between 17°C and 25°C, the current parameter values did not match the observed data, indicating that Cmax should be shifted by about 4°C relative to the current implementation under the bioenergetics model. We conclude that the adjusted parameters for Cmax should produce more accurate predictions from the bioenergetics model for subyearling Chinook Salmon.

  6. Dynamic temperature dependence patterns in future energy demand models in the context of climate change

    International Nuclear Information System (INIS)

    Hekkenberg, M.; Moll, H.C.; Uiterkamp, A.J.M. Schoot

    2009-01-01

    Energy demand depends on outdoor temperature in a 'u' shaped fashion. Various studies have used this temperature dependence to investigate the effects of climate change on energy demand. Such studies contain implicit or explicit assumptions to describe expected socio-economic changes that may affect future energy demand. This paper critically analyzes these implicit or explicit assumptions and their possible effect on the studies' outcomes. First we analyze the interaction between the socio-economic structure and the temperature dependence pattern (TDP) of energy demand. We find that socio-economic changes may alter the TDP in various ways. Next we investigate how current studies manage these dynamics in socio-economic structure. We find that many studies systematically misrepresent the possible effect of socio-economic changes on the TDP of energy demand. Finally, we assess the consequences of these misrepresentations in an energy demand model based on temperature dependence and climate scenarios. Our model results indicate that expected socio-economic dynamics generally lead to an underestimation of future energy demand in models that misrepresent such dynamics. We conclude that future energy demand models should improve the incorporation of socio-economic dynamics. We propose dynamically modeling several key parameters and using direct meteorological data instead of degree days. (author)

  7. Local chemical potential, local hardness, and dual descriptors in temperature dependent chemical reactivity theory.

    Science.gov (United States)

    Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

    2017-05-31

    In this work we establish a new temperature dependent procedure within the grand canonical ensemble, to avoid the Dirac delta function exhibited by some of the second order chemical reactivity descriptors based on density functional theory, at a temperature of 0 K. Through the definition of a local chemical potential designed to integrate to the global temperature dependent electronic chemical potential, the local chemical hardness is expressed in terms of the derivative of this local chemical potential with respect to the average number of electrons. For the three-ground-states ensemble model, this local hardness contains a term that is equal to the one intuitively proposed by Meneses, Tiznado, Contreras and Fuentealba, which integrates to the global hardness given by the difference in the first ionization potential, I, and the electron affinity, A, at any temperature. However, in the present approach one finds an additional temperature-dependent term that introduces changes at the local level and integrates to zero. Additionally, a τ-hard dual descriptor and a τ-soft dual descriptor given in terms of the product of the global hardness and the global softness multiplied by the dual descriptor, respectively, are derived. Since all these reactivity indices are given by expressions composed of terms that correspond to products of the global properties multiplied by the electrophilic or nucleophilic Fukui functions, they may be useful for studying and comparing equivalent sites in different chemical environments.

  8. Temperature dependence of bulk respiration of crop stands. Measurement and model fitting

    International Nuclear Information System (INIS)

    Tani, Takashi; Arai, Ryuji; Tako, Yasuhiro

    2007-01-01

    The objective of the present study was to examine whether the temperature dependence of respiration at a crop-stand scale could be directly represented by an Arrhenius function that was widely used for representing the temperature dependence of leaf respiration. We determined temperature dependences of bulk respiration of monospecific stands of rice and soybean within a range of the air temperature from 15 to 30degC using large closed chambers. Measured responses of respiration rates of the two stands were well fitted by the Arrhenius function (R 2 =0.99). In the existing model to assess the local radiological impact of the anthropogenic carbon-14, effects of the physical environmental factors on photosynthesis and respiration of crop stands are not taken into account for the calculation of the net amount of carbon per cultivation area in crops at harvest which is the crucial parameter for the estimation of the activity concentration of carbon-14 in crops. Our result indicates that the Arrhenius function is useful for incorporating the effect of the temperature on respiration of crop stands into the model which is expected to contribute to a more realistic estimate of the activity concentration of carbon-14 in crops. (author)

  9. Temperature dependency of electrical resistivity of soils; Tsuchi no hiteiko no ondo izonsei ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Park, S; Matsui, T [Osaka University, Osaka (Japan). Faculty of Engineering; Park, M; Fujiwara, H [Osaka University, Osaka (Japan)

    1997-10-22

    Kinds of ground materials, porosity, electrical resistivity of pores, degree of saturation, and content of clays are the factors affecting the electrical resistivity of soils. In addition to these factors, the electrical resistivity of soils around hot spring water and geothermal areas depends on the temperature due to fluctuation of cation mobility in the pore water with the temperature. In this paper, the temperature dependency of electrical resistivity of groundwater and soils is investigated by recognizing that of groundwater as that of pore water. As a result, it was found that the electrical resistivity of groundwater becomes lower as increasing the amount of dissolved cation, and that the temperature dependency of electrical resistivity is not significant because of the small mobility of cation. The electrical resistivity of soils was significantly affected by that of pore water, in which the mobility of cation was changed with temperature changes. Accordingly, the temperature dependency of electrical resistivity of soils has a similar tendency as that of groundwater. 5 refs., 9 figs., 2 tabs.

  10. Observing the temperature dependent transition of the GP2 peptide using terahertz spectroscopy.

    Directory of Open Access Journals (Sweden)

    Yiwen Sun

    Full Text Available The GP2 peptide is derived from the Human Epidermal growth factor Receptor 2 (HER2/nue, a marker protein for breast cancer present in saliva. In this paper we study the temperature dependent behavior of hydrated GP2 at terahertz frequencies and find that the peptide undergoes a dynamic transition between 200 and 220 K. By fitting suitable molecular models to the frequency response we determine the molecular processes involved above and below the transition temperature (T(D. In particular, we show that below T(D the dynamic transition is dominated by a simple harmonic vibration with a slow and temperature dependent relaxation time constant and that above T(D, the dynamic behavior is governed by two oscillators, one of which has a fast and temperature independent relaxation time constant and the other of which is a heavily damped oscillator with a slow and temperature dependent time constant. Furthermore a red shifting of the characteristic frequency of the damped oscillator was observed, confirming the presence of a non-harmonic vibration potential. Our measurements and modeling of GP2 highlight the unique capabilities of THz spectroscopy for protein characterization.

  11. Temperature-dependent behaviours are genetically variable in the nematode Caenorhabditis briggsae.

    Science.gov (United States)

    Stegeman, Gregory W; de Mesquita, Matthew Bueno; Ryu, William S; Cutter, Asher D

    2013-03-01

    Temperature-dependent behaviours in Caenorhabditis elegans, such as thermotaxis and isothermal tracking, are complex behavioural responses that integrate sensation, foraging and learning, and have driven investigations to discover many essential genetic and neural pathways. The ease of manipulation of the Caenorhabditis model system also has encouraged its application to comparative analyses of phenotypic evolution, particularly contrasts of the classic model C. elegans with C. briggsae. And yet few studies have investigated natural genetic variation in behaviour in any nematode. Here we measure thermotaxis and isothermal tracking behaviour in genetically distinct strains of C. briggsae, further motivated by the latitudinal differentiation in C. briggsae that is associated with temperature-dependent fitness differences in this species. We demonstrate that C. briggsae performs thermotaxis and isothermal tracking largely similar to that of C. elegans, with a tendency to prefer its rearing temperature. Comparisons of these behaviours among strains reveal substantial heritable natural variation within each species that corresponds to three general patterns of behavioural response. However, intraspecific genetic differences in thermal behaviour often exceed interspecific differences. These patterns of temperature-dependent behaviour motivate further development of C. briggsae as a model system for dissecting the genetic underpinnings of complex behavioural traits.

  12. Temperature dependence of dynamical permeability characterization of magnetic thin films using shorted microstrip line probe

    International Nuclear Information System (INIS)

    Li, Xiling; Li, Chengyi; Chai, Guozhi

    2017-01-01

    A temperature dependence microwave permeability characterization system of magnetic thin film up to 10 GHz is designed and fabricated. This system can be used at temperatures ranging from room temperature to 200 °C, and is based on a shorted microstrip probe, which is made by microwave printed circuit board. Without contacting the magnetic thin films to the probe, the microwave permeability of the film can be detected without any limitations of sample size and with almost the same accuracy, as shown by comparison with the results obtained from a shorted microstrip transmission-line fixture. The complex permeability can be deduced by an analytical approach from the measured reflection coefficient of a strip line ( S 11 ) with and without a ferromagnetic film material on it. The procedures are the same with the shorted microstrip transmission-line method. The microwave permeability of an oblique deposited CoZr thin film was investigated with this probe. The results show that the room temperature dynamic permeability of the CoZr film is in good agreement with the results obtained from the established short-circuited microstrip perturbation method. The temperature dependence permeability results fit well with the Landau–Lifshitz–Gilbert equation. Development of the temperature-dependent measurement of the magnetic properties of magnetic thin film may be useful for the high-frequency application of magnetic devices at high temperatures. (paper)

  13. Frequency and temperature dependence of ferromagnetic linewidth in exchange biased Permalloy

    International Nuclear Information System (INIS)

    Lubitz, P.; Rubinstein, M.; Krebs, J. J.; Cheng, S.-F.

    2001-01-01

    Ferromagnetic resonance linewidths were measured at 9.5 and 35 GHz and in the temperature range from 77 to 350 K for thin Permalloy (Py) films exchange biased by adjacent layers of NiO, CoO, or IrMn. Compared to unoxidized Py alone, for which the linewidth is nearly temperature independent in this range and scales linearly with frequency, exchange biased Py has broader lines with distinctive temperature dependences for each bias material at 9.5 GHz. Different temperature dependences were observed at 35 GHz. Our results are consistent with relaxation related to thermally driven reversal of the antiferromagnetic grains. Intrinsic damping and inhomogeneities also add to the widths. The qualitative features of the temperature and frequency dependences of the linewidths can be described with the usual expression for the slow relaxation linewidth mechanism. The temperature dependence of the relaxation time is taken from Neel's expression for the reversal time using appropriate rate prefactors and activation energies. [copyright] 2001 American Institute of Physics

  14. Modeling and Compensating Temperature-Dependent Non-Uniformity Noise in IR Microbolometer Cameras

    Directory of Open Access Journals (Sweden)

    Alejandro Wolf

    2016-07-01

    Full Text Available Images rendered by uncooled microbolometer-based infrared (IR cameras are severely degraded by the spatial non-uniformity (NU noise. The NU noise imposes a fixed-pattern over the true images, and the intensity of the pattern changes with time due to the temperature instability of such cameras. In this paper, we present a novel model and a compensation algorithm for the spatial NU noise and its temperature-dependent variations. The model separates the NU noise into two components: a constant term, which corresponds to a set of NU parameters determining the spatial structure of the noise, and a dynamic term, which scales linearly with the fluctuations of the temperature surrounding the array of microbolometers. We use a black-body radiator and samples of the temperature surrounding the IR array to offline characterize both the constant and the temperature-dependent NU noise parameters. Next, the temperature-dependent variations are estimated online using both a spatially uniform Hammerstein-Wiener estimator and a pixelwise least mean squares (LMS estimator. We compensate for the NU noise in IR images from two long-wave IR cameras. Results show an excellent NU correction performance and a root mean square error of less than 0.25 ∘ C, when the array’s temperature varies by approximately 15 ∘ C.

  15. Modelled temperature-dependent excitability behaviour of a generalised human peripheral sensory nerve fibre.

    Science.gov (United States)

    Smit, Jacoba E; Hanekom, Tania; Hanekom, Johan J

    2009-08-01

    The objective of this study was to determine if a recently developed human Ranvier node model, which is based on a modified version of the Hodgkin-Huxley model, could predict the excitability behaviour in human peripheral sensory nerve fibres with diameters ranging from 5.0 to 15.0 microm. The Ranvier node model was extended to include a persistent sodium current and was incorporated into a generalised single cable nerve fibre model. Parameter temperature dependence was included. All calculations were performed in Matlab. Sensory nerve fibre excitability behaviour characteristics predicted by the new nerve fibre model at different temperatures and fibre diameters compared well with measured data. Absolute refractory periods deviated from measured data, while relative refractory periods were similar to measured data. Conduction velocities showed both fibre diameter and temperature dependence and were underestimated in fibres thinner than 12.5 microm. Calculated strength-duration time constants ranged from 128.5 to 183.0 micros at 37 degrees C over the studied nerve fibre diameter range, with chronaxie times about 30% shorter than strength-duration time constants. Chronaxie times exhibited temperature dependence, with values overestimated by a factor 5 at temperatures lower than body temperature. Possible explanations include the deviated absolute refractory period trend and inclusion of a nodal strangulation relationship.

  16. The temperature dependence of quantum spin pumping generated using electron spin resonance with three-magnon splittings

    International Nuclear Information System (INIS)

    Nakata, Kouki

    2013-01-01

    On the basis of the Schwinger–Keldysh formalism, we have closely investigated the temperature dependence of quantum spin pumping generated using electron spin resonance. We have clarified that three-magnon splittings excite non-zero modes of magnons and characterize the temperature dependence of quantum spin pumping generated using electron spin resonance. (paper)

  17. Temperature-dependent Raman spectroscopy studies of the interface coupling effect of monolayer ReSe2 single crystals on Au foils

    Science.gov (United States)

    Jiang, Shaolong; Zhao, Liyun; Shi, Yuping; Xie, Chunyu; Zhang, Na; Zhang, Zhepeng; Huan, Yahuan; Yang, Pengfei; Hong, Min; Zhou, Xiebo; Shi, Jianping; Zhang, Qing; Zhang, Yanfeng

    2018-05-01

    Rhenium diselenide (ReSe2), which bears in-plane anisotropic optical and electrical properties, is of considerable interest for its excellent applications in novel devices, such as polarization-sensitive photodetectors and integrated polarization-controllers. However, great challenges to date in the controllable synthesis of high-quality ReSe2 have hindered its in-depth investigations and practical applications. Herein, we report a feasible synthesis of monolayer single-crystal ReSe2 flakes on the Au foil substrate by using a chemical vapor deposition route. Particularly, we focus on the temperature-dependent Raman spectroscopy investigations of monolayer ReSe2 grown on Au foils, which present concurrent red shifts of Eg-like and Ag-like modes with increasing measurement temperature from 77–290 K. Linear temperature dependences of both modes are revealed and explained from the anharmonic vibration of the ReSe2 lattice. More importantly, the strong interaction of ReSe2 with Au, with respect to that with SiO2/Si, is further confirmed by temperature-dependent Raman characterization. This work is thus proposed to shed light on the optical and thermal properties of such anisotropic two-dimensional three-atom-thick materials.

  18. Impact of ion-implantation-induced band gap engineering on the temperature-dependent photoluminescence properties of InAs/InP quantum dashes

    International Nuclear Information System (INIS)

    Hadj Alouane, M. H.; Ilahi, B.; Maaref, H.; Salem, B.; Aimez, V.; Morris, D.; Turala, A.; Regreny, P.; Gendry, M.

    2010-01-01

    We report on the effects of the As/P intermixing induced by phosphorus ion implantation in InAs/InP quantum dashes (QDas) on their photoluminescence (PL) properties. For nonintermixed QDas, usual temperature-dependent PL properties characterized by a monotonic redshift in the emission band and a continual broadening of the PL linewidth as the temperature increases, are observed. For intermediate ion implantation doses, the inhomogeneous intermixing enhances the QDas size dispersion and the enlarged distribution of carrier confining potential depths strongly affects the temperature-dependent PL properties below 180 K. An important redshift in the PL emission band occurs between 10 and 180 K which is explained by a redistribution of carriers among the different intermixed QDas of the ensemble. For higher implantation doses, the homogeneous intermixing reduces the broadening of the localized QDas state distribution and the measured linewidth temperature behavior matches that of the nonintermixed QDas. An anomalous temperature-dependent emission energy behavior has been observed for extremely high implantation doses, which is interpreted by a possible QDas dissolution.

  19. Angle and temperature dependence of the magnetocrystalline anisotropy energy and the microscopic magnetic moments of the ferromagnetic semi-metal CrO{sub 2}; Winkel- und Temperaturabhaengigkeit der magnetokristallinen Anisotropieenergie und der mikroskopischen magnetischen Momente des ferromagnetischen Halbmetalls CrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gold, S.

    2005-07-01

    The aim of this work was to examine, by use of XMCD-effect and additional measurements with SQUID-magnetometer, spin moments and hysteresis loops, but also to clarify the intrinsic properties like magnetocrystalline anisotropy, magnetic dipole term, and the nearly quenched orbital moment. The XMCD-measurements were done at the Cr L{sub 2,3}- and the O K-edge. The results for CrO{sub 2} show a strong dependence of the orbital, the sum of spin moment and magnetic dipole term, and the magnetocrystalline anisotropy energy from the angle between rutile a- and c-axis. Even more than the complete orbital moment, two separable and different spectral features show strong alterations of the different orbital moments. In a second part of this work the temperature dependence was investigated. The aim was to clarify the origin of the orbital moment, dipole term, and MAE in dependence of the spin moment and compare the results to different theoretical models. The extracted orbital moments and the magnetic dipole term show the same temperature dependence as the spin moment. In the following a dependence of the squared measured spin moment could be found for the MAE. For the first time the magnetic dipole term could be identified as the reason of the magnetocrystalline anisotropy energy. A strong Cr-O hybridisation was found, which shows in a similar structure and temperature dependence of the orbital moments for Cr L{sub 2,3} and the XMCD effect at O-K edge. (orig.)

  20. Temperature Dependence of Interband Transitions in Wurtzite InP Nanowires.

    Science.gov (United States)

    Zilli, Attilio; De Luca, Marta; Tedeschi, Davide; Fonseka, H Aruni; Miriametro, Antonio; Tan, Hark Hoe; Jagadish, Chennupati; Capizzi, Mario; Polimeni, Antonio

    2015-04-28

    Semiconductor nanowires (NWs) formed by non-nitride III-V compounds grow preferentially with wurtzite (WZ) lattice. This is contrary to bulk and two-dimensional layers of the same compounds, where only zincblende (ZB) is observed. The absorption spectrum of WZ materials differs largely from their ZB counterparts and shows three transitions, referred to as A, B, and C in order of increasing energy, involving the minimum of the conduction band and different critical points of the valence band. In this work, we determine the temperature dependence (T = 10-310 K) of the energy of transitions A, B, and C in ensembles of WZ InP NWs by photoluminescence (PL) and PL excitation (PLE) spectroscopy. For the whole temperature and energy ranges investigated, the PL and PLE spectra are quantitatively reproduced by a theoretical model taking into account contribution from both exciton and continuum states. WZ InP is found to behave very similarly to wide band gap III-nitrides and II-VI compounds, where the energy of A, B, and C displays the same temperature dependence. This finding unveils a general feature of the thermal properties of WZ materials that holds regardless of the bond polarity and energy gap of the crystal. Furthermore, no differences are observed in the temperature dependence of the fundamental band gap energy in WZ InP NWs and ZB InP (both NWs and bulk). This result points to a negligible role played by the WZ/ZB differences in determining the deformation potentials and the extent of the electron-phonon interaction that is a direct consequence of the similar nearest neighbor arrangement in the two lattices.

  1. Temperature-dependent changes in the host-seeking behaviors of parasitic nematodes.

    Science.gov (United States)

    Lee, Joon Ha; Dillman, Adler R; Hallem, Elissa A

    2016-05-06

    Entomopathogenic nematodes (EPNs) are lethal parasites of insects that are of interest as biocontrol agents for insect pests and disease vectors. Although EPNs have been successfully commercialized for pest control, their efficacy in the field is often inconsistent for reasons that remain elusive. EPN infective juveniles (IJs) actively search for hosts to infect using a diverse array of host-emitted odorants. Here we investigate whether their host-seeking behavior is subject to context-dependent modulation. We find that EPN IJs exhibit extreme plasticity of olfactory behavior as a function of cultivation temperature. Many odorants that are attractive for IJs grown at lower temperatures are repulsive for IJs grown at higher temperatures and vice versa. Temperature-induced changes in olfactory preferences occur gradually over the course of days to weeks and are reversible. Similar changes in olfactory behavior occur in some EPNs as a function of IJ age. EPNs also show temperature-dependent changes in their host-seeking strategy: IJs cultured at lower temperatures appear to more actively cruise for hosts than IJs cultured at higher temperatures. Furthermore, we find that the skin-penetrating rat parasite Strongyloides ratti also shows temperature-dependent changes in olfactory behavior, demonstrating that such changes occur in mammalian-parasitic nematodes. IJs are developmentally arrested and long-lived, often surviving in the environment through multiple seasonal temperature changes. Temperature-dependent modulation of behavior may enable IJs to optimize host seeking in response to changing environmental conditions, and may play a previously unrecognized role in shaping the interactions of both beneficial and harmful parasitic nematodes with their hosts.

  2. Temperature dependent dynamics of DegP-trimer: A molecular dynamics study

    Directory of Open Access Journals (Sweden)

    Nivedita Rai

    2015-01-01

    Full Text Available DegP is a heat shock protein from high temperature requirement protease A family, which reacts to the environmental stress conditions in an ATP independent way. The objective of the present analysis emerged from the temperature dependent functional diversity of DegP between chaperonic and protease activities at temperatures below and above 28 °C, respectively. DegP is a multimeric protein and the minimal functional unit, DegP-trimer, is of great importance in understanding the DegP pathway. The structural aspects of DegP-trimer with respect to temperature variation have been studied using molecular dynamics simulations (for 100 ns and principal component analysis to highlight the temperature dependent dynamics facilitating its functional diversity. The DegP-trimer revealed a pronounced dynamics at both 280 and 320 K, when compared to the dynamics observed at 300 K. The LA loop is identified as the highly flexible region during dynamics and at extreme temperatures, the residues 46–80 of LA loop express a flip towards right (at 280 and left ( at 320 K with respect to the fixed β-sheet connecting the LA loop of protease for which Phe46 acts as one of the key residues. Such dynamics of LA loop facilitates inter-monomeric interaction with the PDZ1 domain of the neighbouring monomer and explains its active participation when DegP exists as trimer. Hence, the LA loop mediated dynamics of DegP-trimer is expected to provide further insight into the temperature dependent dynamics of DegP towards the understanding of its assembly and functional diversity in the presence of substrate.

  3. The temperature dependence of the momentum distribution of beryllium measured by neutron Compton scattering

    International Nuclear Information System (INIS)

    Fielding, A.L.; Timms, D.; Mayers, J.

    1999-01-01

    A new neutron Compton scattering (NCS) measurement of the temperature dependence of the kinetic energy in polycrystalline beryllium at momentum transfers in the range 27.91 to 104.21 A -1 is presented. The measurements have been made with the Electron Volt Spectrometer (eVS) at the ISIS facility and the measured kinetic energies are shown to be in good agreement with calculations made in the harmonic approximation. Numerical simulations are also presented based on the Sears expansion which predict that final state effects in NCS experiments become less significant at elevated temperatures. (author)

  4. Temperature-dependent evolution of chemisorbed digermane in Ge thin film growth

    International Nuclear Information System (INIS)

    Eres, D.; Sharp, J.W.

    1992-01-01

    The formation and evolution of chemisorbed digermane layers in context with germanium thin film growth was investigated by time- resolved surface reflectometry. Modulation of the source gas supply made possible the separation and independent study of the temperature dependence of the adsorption and desorption processes. The regeneration of active sites by molecular hydrogen desorption was identified as the rate-limiting step at low substrate temperatures. A dynamic method of thin film growth was demonstrated by repetitively replenishing the active film growth sites regenerated between two successive source gas pulses. The film growth rate was shown to be related to the substrate temperature and the delay time between successive source gas pulses

  5. A temperature-dependent theory for HeII: Application to the liquid structure factor

    International Nuclear Information System (INIS)

    Chela-Flores, J.; Ghassib, H.B.

    1981-08-01

    A temperature-dependent theory is presented for HeII, which is based on both a gauge-theoretic formulation as well as a mean-field (Hartree) approach. A simple model calculation is then performed within this framework for the liquid structure factor of the system. In particular, explicit expressions are obtained for the low-momentum-transfer and low-temperature limits, which seem to conform with the available experimental data. Further, the curvature of the structure factor is predicted, under these circumstances, to be only mildly dependent on temperature. Throughout, we compare and contrast with other theoretical attempts, including Feynman's. (author)

  6. Temperature dependence of the electric field gradient in AgPd and AgPt alloys

    International Nuclear Information System (INIS)

    Krolas, K.

    1977-07-01

    The measurements of temperature dependence of the electric field gradient (EFG) on 111 Cd nuclei in AgPd and AgPt alloys were performed using the time dependent perturbed angular correlation method. The EFG caused by impurities distributed in further coordination shells decrease stronaer with increasing temperature than the EFG due to single impurity being the nearest neighbour of the probe atom. These results were explained assuming different modes of thermal vibrations of single impurity atoms and impurity complexes in silver host lattice. (author)

  7. Tiny optical fiber temperature sensor based on temperature-dependent refractive index of zinc telluride film

    Science.gov (United States)

    Bian, Qiang; Song, Zhangqi; Song, Dongyu; Zhang, Xueliang; Li, Bingsheng; Yu, Yang; Chen, Yuzhong

    2018-03-01

    The temperature-dependent refractive index of zinc telluride film can be used to develop a tiny, low cost and film-coated optical fiber temperature sensor. Pulse reference-based compensation technique is used to largely reduce the background noise which makes it possible to detect the minor reflectivity change of the film in different temperatures. The temperature sensitivity is 0.0034dB/° and the background noise is measured to be 0.0005dB, so the resolution can achieve 0.2°.

  8. Temperature dependence of Raman scattering by optical phonons in ZnTe

    International Nuclear Information System (INIS)

    Simmonds, P.E.; Martin, A.D.

    1987-01-01

    Measurements of the temperature dependence of Raman scattering by optical phonons between temperatures 5 K and 293 K in the II-VI semiconductor ZnTe are reported. Typical Raman spectra for ZnTe at different temperatures are shown and values of the measured LO and TO phonon Raman shifts and linewidths are given for T = 5, 77, and 293 K. The measured linewidth of the LO Raman line as a function of temperature is plotted and compared with model predictions based on various three- and four-phonon processes

  9. Temperature dependence of the fracture toughness and the cleavage fracture strength of a pressure vessel steel

    International Nuclear Information System (INIS)

    Kotilainen, H.

    1980-01-01

    A new model for the temperature dependence of the fracture toughness has been sought. It is based on the yielding processes at the crack tip, which are thought to be competitive with fracture. Using this method a good correlation between measured and calculated values of fracture toughness has been found for a Cr-Mo-V pressure vessel steel as well as for A533B. It has been thought that the application of this method can reduce the number of surveillance specimens in nuclear reactors. A method for the determination of the cleavage fracture strength has been proposed. 28 refs

  10. Flow of chemically reactive magneto Cross nanoliquid with temperature-dependent conductivity

    Science.gov (United States)

    Hayat, Tasawar; Ullah, Ikram; Waqas, Muhammad; Alsaedi, Ahmed

    2018-05-01

    Influence of temperature-dependent thermal conductivity on MHD flow of Cross nanoliquid bounded by a stretched sheet is explored. The combined feature of Brownian motion and thermophoresis in nanoliquid modeling is retained. In addition, the attributes of zero mass flux at sheet are imposed. First-order chemical reaction is retained. The resulting problems are numerically computed. Plots and tabulated values are presented and examined. It is figured out that larger thermophoretic diffusion and thermal conductivity significantly rise the thermal field, whereas opposite situation is seen for heat transfer rate.

  11. Temperature dependence of carrier transfer and exciton localization in ZnO/MgZnO heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Dongxu [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China)]. E-mail: dxzhao2000@yahoo.com.cn; Li Binghui [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Center for Advanced Optoelectronic Functional Material Research, Northeast Normal University, Changchun 130024 (China); Wu Chunxia [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences (China); Lu Youming [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Shen Dezhen [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Zhang Jiying [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Fan Xiwu [Key Laboratory of Excited State Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China)

    2006-07-15

    MgZnO/ZnO heterostructure was fabricated on sapphire substrate by plasma assistant molecular beam epitaxy. The micro-photoluminescence spectra of sample are reported, which shows that different emission peaks would appear when the laser beam focuses different deepness in the film. A carrier tunneling process from the MgZnO capping layer to ZnO layer was observed by the measured temperature dependence of photoluminescence spectra. This induces the emission intensity of the ZnO grew monotonically from 81 to 103 K.

  12. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    International Nuclear Information System (INIS)

    Deb, K.; Bera, A.; Saha, B.; Bhowmik, K. L.; Chattopadhyay, K. K.

    2016-01-01

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  13. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Deb, K.; Bera, A.; Saha, B., E-mail: biswajit.physics@gmail.com [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Bhowmik, K. L. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Department of Chemistry, Bir Bikram Memorial College, Agartala, West Tripura 799004 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

    2016-05-23

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  14. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    Science.gov (United States)

    Deb, K.; Bhowmik, K. L.; Bera, A.; Chattopadhyay, K. K.; Saha, B.

    2016-05-01

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  15. Magnetic field and temperature dependence of the critical vortex velocity in type-II superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, G; Leo, A; Cirillo, C; Attanasio, C; Nigro, A; Pace, S [CNR-INFM Laboratorio Regionale SuperMat, Via Salvador Allende, I-84081 Baronissi (Italy)], E-mail: grimaldi@sa.infn.it

    2009-06-24

    We study the vortex dynamics in the instability regime induced by high dissipative states well above the critical current in Nb superconducting strips. The magnetic field and temperature behavior of the critical vortex velocity corresponding to the observed dynamic instability is ascribed to intrinsic non-equilibrium phenomena. The Larkin-Ovchinnikov (LO) theory of electronic instability in high velocity vortex motion has been applied to interpret the temperature dependence of the critical vortex velocity. The magnetic field dependence of the vortex critical velocity shows new features in the low-field regime not predicted by LO.

  16. Suppressing gravitino thermal production with a temperature-dependent messenger coupling

    International Nuclear Information System (INIS)

    Badziak, Marcin; Dalianis, Ioannis; Lalak, Zygmunt

    2016-01-01

    We show that the constraints on GMSB theories from the gravitino cosmology can be significantly relaxed if the messenger-spurion coupling is temperature dependent. We demonstrate this novel mechanism in a scenario in which this coupling depends on the VEV of an extra singlet field S that interacts with the thermalized plasma which can result in a significantly suppressed gravitino production rate. In such a scenario the relic gravitino abundance is determined by the thermal dynamics of the S field and it is easy to fit the observed dark matter abundance evading the stringent constraints on the reheating temperature, thus making gravitino dark matter consistent with thermal leptogenesis.

  17. Temperature dependence of spectral linewidth of InAs/InP quantum dot distributed feedback lasers

    Science.gov (United States)

    Duan, J.; Huang, H.; Schires, K.; Poole, P. J.; Wang, C.; Grillot, F.

    2018-02-01

    In this paper, we investigate the temperature dependence of spectral linewidth of InAs/InP quantum dot distributed feedback lasers. In comparison with their quantum well counterparts, results show that quantum dot lasers have spectral linewidths rather insensitive to the temperature with minimum values below 200 kHz in the range of 283K to 303K. The experimental results are also well confirmed by numerical simulations. Overall, this work shows that quantum dot lasers are excellent candidates for various applications such as coherent communication systems, high-resolution spectroscopy, high purity photonic microwave generation and on-chip atomic clocks.

  18. Temperature dependence of photoluminescence from submonolayer deposited InGaAs/GaAs quantum dots

    DEFF Research Database (Denmark)

    Xu, Zhangcheng; Leosson, K.; Birkedal, Dan

    2002-01-01

    The temperature dependence of photoluminescence (PL) from self-assembled InGaAs quantum dots (QD's) grown by submonolayer deposition mode (non-SK mode), is investigated. It is found that the PL spectra are dominated by the ground-state transitions at low temperatures, but increasingly...... by the excited-state transitions at higher temperatures. The emission linewidth of the ground-state transitions of QDs ensembles first decreases and then increases with the increase of temperature, which results from the carrier transfer between dots via barrier states....

  19. Temperature dependence of the optical conductivity and penetration depth in superconductor MgB2 film

    International Nuclear Information System (INIS)

    Moarrefi, M.; Yavari, H.; Elahi, M.

    2010-01-01

    By using Green's function method the temperature dependence of the optical conductivity and penetration depth of high-quality MgB 2 film are calculated in the framework of the two-band model. We compare our results with experimental data and we argue that the single gap model is insufficient to describe the optical and penetration depth behavior, but the two-band model with different symmetries describes the data rather well. In the two gap model we consider that the both components of optical conductivity are a weighted sum of the contribution from σ and π bonds and hybridization between them is negligible.

  20. Temperature-dependent index of refraction of monoclinic Ga2O3 single crystal.

    Science.gov (United States)

    Bhaumik, Indranil; Bhatt, R; Ganesamoorthy, S; Saxena, A; Karnal, A K; Gupta, P K; Sinha, A K; Deb, S K

    2011-11-01

    We present temperature-dependent refractive index along crystallographic b[010] and a direction perpendicular to (100)-plane for monoclinic phase (β) Ga(2)O(3) single crystal grown by the optical floating zone technique. The experimental results are consistent with the theoretical result of Litimein et al.1. Also, the Sellmeier equation for wavelengths in the range of 0.4-1.55 μm is formulated at different temperatures in the range of 30-175 °C. The thermal coefficient of refractive index in the above specified range is ~10(-5)/°C. © 2011 Optical Society of America

  1. Temperature Dependence of Quasiparticle Spectral Weight and Coherence in High Tc Superconductors

    Science.gov (United States)

    He, Yang; Zhang, Jessie; Hoffman, Jennifer; Hoffman Lab Team

    2014-03-01

    Superconductivity arises from the Cooper pairing of quasiparticles on the Fermi surface. Understanding the formation of Cooper pairs is an essential step towards unveiling the mechanism of high Tc superconductivity. We compare scanning tunneling microscope investigations of the temperature dependence of quasiparticle spectral weight and quasiparticle interference in several families of high Tc materials. We calculate the coherent spectral weight related to superconductivity, despite the coexistence of competing orders. The relation between pairing temperature and coherent spectral weight is discussed. We acknowledge support by the New York Community Trust-George Merck Fund.

  2. Temperature dependence of the luminescence lifetime of a europium complex immobilized in different polymer matrices

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Bharathi Bai J. [Surface Engineering Division, National Aerospace Laboratories, Bangalore 560017 (India)], E-mail: bharathi@css.nal.res.in; Vasantharajan, N. [Surface Engineering Division, National Aerospace Laboratories, Bangalore 560017 (India)

    2008-10-15

    The temperature dependence of the luminescence lifetime of temperature sensor films based on europium (III) thenoyltrifluoroacetonate (EuTTA) as sensor dye in various polymer matrices such as polystyrene (PS), polymethylmethacrylate (PMMA), polyurethane (PU) and model airplane dope was studied and compared. The luminescence lifetime of EuTTA was found to depend on the polymer matrix. The temperature sensitivity of lifetime was maximum for EuTTA-PS coating in the temperature range of 10-60 deg. C. The effect of concentration of the sensor dye in the polymer on the lifetime and temperature sensitivity was also studied.

  3. Study of the temperature dependence of giant magnetoresistance in metallic granular composite

    International Nuclear Information System (INIS)

    Ju Sheng; Li, Z.-Y.

    2002-01-01

    The temperature dependence of the giant magnetoresistance of metallic granular composite is studied. It is considered that the composite contains both large magnetic grains with surface spin S' and small magnetic impurities. It is found that the decrease of surface spin S' of grain is the main cause of an almost linear decrease of giant magnetoresistance with the increase of temperature in high temperature range. The magnetic impurities, composed of several atoms, lead to an almost linear increase of the giant magnetoresistance with the decrease of temperature in low temperature range. Our calculations are in good agreement with recent experimental data for metallic nanogranular composites

  4. Towards a comprehensive theory for He II: A temperature-dependent field-theoretic approach

    International Nuclear Information System (INIS)

    Ghassib, H.B.; Chela-Flores, J.

    1983-07-01

    New experimental aspects of He II, as well as recent developments in particle physics, are invoked to construct the rudiments of a comprehensive theory in which temperature-dependent U(1) and SU(2) gauge fields are incorporated into a hierarchy of effective Lagrangians. It is conjectured that an SU(n) gauge-theoretic description of superfluidity may be obtained in the limit n→infinity. However, it is outlined how experiments can be understood in the zeroth, first and second order of the hierarchy. (author)

  5. Temperature dependence of mode conversion in warm, unmagnetized plasmas with a linear density profile

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dae Jung; Lee, Dong-Hun [School of Space Research, Kyung Hee University, Yongin (Korea, Republic of); Kim, Kihong [Division of Energy Systems Research, Ajou University, Suwon (Korea, Republic of)

    2013-06-15

    We study theoretically the linear mode conversion between electromagnetic waves and Langmuir waves in warm, stratified, and unmagnetized plasmas, using a numerically precise calculation based on the invariant imbedding method. We verify that the principle of reciprocity for the forward and backward mode conversion coefficients holds precisely regardless of temperature. We also find that the temperature dependence of the mode conversion coefficient is substantially stronger than that previously reported. Depending on the wave frequency and the incident angle, the mode conversion coefficient is found to increase or decrease with the increase of temperature.

  6. Leading temperature dependence of the conductance in Kondo-correlated quantum dots

    Science.gov (United States)

    Aligia, A. A.

    2018-04-01

    Using renormalized perturbation theory in the Coulomb repulsion, we derive an analytical expression for the leading term in the temperature dependence of the conductance through a quantum dot described by the impurity Anderson model, in terms of the renormalized parameters of the model. Taking these parameters from the literature, we compare the results with published ones calculated using the numerical renormalization group obtaining a very good agreement. The approach is superior to alternative perturbative treatments. We compare in particular to the results of a simple interpolative perturbation approach.

  7. Riemann solvers for multi-component gas mixtures with temperature dependent heat capacities

    International Nuclear Information System (INIS)

    Beccantini, A.

    2001-01-01

    This thesis represents a contribution to the development of upwind splitting schemes for the Euler equations for ideal gaseous mixtures and their investigation in computing multidimensional flows in irregular geometries. In the preliminary part we develop and investigate the parameterization of the shock and rarefaction curves in the phase space. Then, we apply them to perform some field-by-field decompositions of the Riemann problem: the entropy-respecting one, the one which supposes that genuinely-non-linear (GNL) waves are both shocks (shock-shock one) and the one which supposes that GNL waves are both rarefactions (rarefaction-rarefaction one). We emphasize that their analysis is fundamental in Riemann solvers developing: the simpler the field-by-field decomposition, the simpler the Riemann solver based on it. As the specific heat capacities of the gases depend on the temperature, the shock-shock field-by-field decomposition is the easiest to perform. Then, in the second part of the thesis, we develop an upwind splitting scheme based on such decomposition. Afterwards, we investigate its robustness, precision and CPU-time consumption, with respect to some of the most popular upwind splitting schemes for polytropic/non-polytropic ideal gases. 1-D test-cases show that this scheme is both precise (exact capturing of stationary shock and stationary contact) and robust in dealing with strong shock and rarefaction waves. Multidimensional test-cases show that it suffers from some of the typical deficiencies which affect the upwind splitting schemes capable of exact capturing stationary contact discontinuities i.e the developing of non-physical instabilities in computing strong shock waves. In the final part, we use the high-order multidimensional solver here developed to compute fully-developed detonation flows. (author)

  8. Determination of Temperature-Dependent Stress State in Thin AlGaN Layer of AlGaN/GaN HEMT Heterostructures by Near-Resonant Raman Scattering

    OpenAIRE

    Yanli Liu; Xifeng Yang; Dunjun Chen; Hai Lu; Rong Zhang; Youdou Zheng

    2015-01-01

    The temperature-dependent stress state in the AlGaN barrier layer of AlGaN/GaN heterostructure grown on sapphire substrate was investigated by ultraviolet (UV) near-resonant Raman scattering. Strong scattering peak resulting from the A1(LO) phonon mode of AlGaN is observed under near-resonance condition, which allows for the accurate measurement of Raman shifts with temperature. The temperature-dependent stress in the AlGaN layer determined by the resonance Raman spectra is consistent with th...

  9. Band spectrum transformation and temperature dependences of thermoelectric power of Hg1-xRxBa2Ca2Cu3O8+δ system

    Directory of Open Access Journals (Sweden)

    M. Vasyuk

    2011-03-01

    Full Text Available Temperature dependences of thermoelectric power S(T at T>Tc of the Hg-based high temperature superconductors Hg1-xRxBa2Ca2Cu3O8+δ (R=Re, Pb have been analyzed with accounting for strong scattering of charge carriers. Transformation of parameters of a narrow conducting band in the region of the Fermi level was studied. The existence of correlation between the effective bandwidth and the temperature of a superconductive transition Tc is shown.

  10. Improved Regression Analysis of Temperature-Dependent Strain-Gage Balance Calibration Data

    Science.gov (United States)

    Ulbrich, N.

    2015-01-01

    An improved approach is discussed that may be used to directly include first and second order temperature effects in the load prediction algorithm of a wind tunnel strain-gage balance. The improved approach was designed for the Iterative Method that fits strain-gage outputs as a function of calibration loads and uses a load iteration scheme during the wind tunnel test to predict loads from measured gage outputs. The improved approach assumes that the strain-gage balance is at a constant uniform temperature when it is calibrated and used. First, the method introduces a new independent variable for the regression analysis of the balance calibration data. The new variable is designed as the difference between the uniform temperature of the balance and a global reference temperature. This reference temperature should be the primary calibration temperature of the balance so that, if needed, a tare load iteration can be performed. Then, two temperature{dependent terms are included in the regression models of the gage outputs. They are the temperature difference itself and the square of the temperature difference. Simulated temperature{dependent data obtained from Triumph Aerospace's 2013 calibration of NASA's ARC-30K five component semi{span balance is used to illustrate the application of the improved approach.

  11. Experimental investigation of the energy and temperature dependence of beryllium self sputtering

    International Nuclear Information System (INIS)

    Korshunov, S.N.; Guseva, M.I.; Stolijarova, V.G.

    1995-01-01

    The low-Z metal beryllium is considered as plasma facing material (PFM) for the ITER. It is expected that operation temperature range of beryllium PFM will be (670 - 1070) K. While experimental Be-sputtering data bases exist for H + , D + and He + -ions, the self-sputtering yields of Be have only been estimated by computer simulation. In this paper we report the experimental results on the energy and temperature dependence of the beryllium self-sputtering yield (S). The energy dependence of S s in the energy range (0.5 - 10.0) keV was measured at 670 K. The self-sputtering yield of Be attains its maximal value at the ion energy of 1.5 keV, being equal to 0.32 ± at./ion. Comparison of the experimental results and theoretical prediction shows a good agreement for energy dependence of S s . The temperature dependence of S s in the temperature range (370-1070)K was obtained for 0.9keV Be + -ions. The value of S s is not changed up to 870 K. It sharply increases at the temperatures above 870 attaining the value of 0.75 at./ion at 1070 K

  12. A micromechanical interpretation of the temperature dependence of Beremin model parameters for French RPV steel

    International Nuclear Information System (INIS)

    Mathieu, Jean-Philippe; Inal, Karim; Berveiller, Sophie; Diard, Olivier

    2010-01-01

    Local approach to brittle fracture for low-alloyed steels is discussed in this paper. A bibliographical introduction intends to highlight general trends and consensual points of the topic and evokes debatable aspects. French RPV steel 16MND5 (equ. ASTM A508 Cl.3), is then used as a model material to study the influence of temperature on brittle fracture. A micromechanical modelling of brittle fracture at the elementary volume scale already used in previous work is then recalled. It involves a multiscale modelling of microstructural plasticity which has been tuned on experimental inter-phase and inter-granular stresses heterogeneities measurements. Fracture probability of the elementary volume can then be computed using a randomly attributed defect size distribution based on realistic carbides repartition. This defect distribution is then deterministically correlated to stress heterogeneities simulated within the microstructure using a weakest-link hypothesis on the elementary volume, which results in a deterministic stress to fracture. Repeating the process allows to compute Weibull parameters on the elementary volume. This tool is then used to investigate the physical mechanisms that could explain the already experimentally observed temperature dependence of Beremin's parameter for 16MND5 steel. It is showed that, assuming that the hypothesis made in this work about cleavage micro-mechanisms are correct, effective equivalent surface energy (i.e. surface energy plus plastically dissipated energy when blunting the crack tip) for propagating a crack has to be temperature dependent to explain Beremin's parameters temperature evolution.

  13. Temperature-dependent transformation thermotics for unsteady states: Switchable concentrator for transient heat flow

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying, E-mail: 13110290008@fudan.edu.cn [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China); Shen, Xiangying, E-mail: 13110190068@fudan.edu.cn [Department of Physics, State Key Laboratory of Surface Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Huang, Jiping, E-mail: jphuang@fudan.edu.cn [Department of Physics, State Key Laboratory of Surface Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Ni, Yushan, E-mail: niyushan@fudan.edu.cn [Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433 (China)

    2016-04-22

    For manipulating heat flow efficiently, recently we established a theory of temperature-dependent transformation thermotics which holds for steady-state cases. Here, we develop the theory to unsteady-state cases by considering the generalized Fourier's law for transient thermal conduction. As a result, we are allowed to propose a new class of intelligent thermal metamaterial — switchable concentrator, which is made of inhomogeneous anisotropic materials. When environmental temperature is below or above a critical value, the concentrator is automatically switched on, namely, it helps to focus heat flux in a specific region. However, the focusing does not affect the distribution pattern of temperature outside the concentrator. We also perform finite-element simulations to confirm the switching effect according to the effective medium theory by assembling homogeneous isotropic materials, which bring more convenience for experimental fabrication than inhomogeneous anisotropic materials. This work may help to figure out new intelligent thermal devices, which provide more flexibility in controlling heat flow, and it may also be useful in other fields that are sensitive to temperature gradient, such as the Seebeck effect. - Highlights: • Established the unsteady-state temperature dependent transformation thermotics. • A thermal concentrator with switchable functionality. • An effective-medium design for experimental realization.

  14. Temperature-dependent growth of Geomyces destructans, the fungus that causes bat white-nose syndrome.

    Directory of Open Access Journals (Sweden)

    Michelle L Verant

    Full Text Available White-nose syndrome (WNS is an emergent disease estimated to have killed over five million North American bats. Caused by the psychrophilic fungus Geomyces destructans, WNS specifically affects bats during hibernation. We describe temperature-dependent growth performance and morphology for six independent isolates of G. destructans from North America and Europe. Thermal performance curves for all isolates displayed an intermediate peak with rapid decline in performance above the peak. Optimal temperatures for growth were between 12.5 and 15.8°C, and the upper critical temperature for growth was between 19.0 and 19.8°C. Growth rates varied across isolates, irrespective of geographic origin, and above 12°C all isolates displayed atypical morphology that may have implications for proliferation of the fungus. This study demonstrates that small variations in temperature, consistent with those inherent of bat hibernacula, affect growth performance and physiology of G. destructans, which may influence temperature-dependent progression and severity of WNS in wild bats.

  15. Temperature-dependent growth of Geomyces destructans, the fungus that causes bat white-nose syndrome.

    Science.gov (United States)

    Verant, Michelle L; Boyles, Justin G; Waldrep, William; Wibbelt, Gudrun; Blehert, David S

    2012-01-01

    White-nose syndrome (WNS) is an emergent disease estimated to have killed over five million North American bats. Caused by the psychrophilic fungus Geomyces destructans, WNS specifically affects bats during hibernation. We describe temperature-dependent growth performance and morphology for six independent isolates of G. destructans from North America and Europe. Thermal performance curves for all isolates displayed an intermediate peak with rapid decline in performance above the peak. Optimal temperatures for growth were between 12.5 and 15.8°C, and the upper critical temperature for growth was between 19.0 and 19.8°C. Growth rates varied across isolates, irrespective of geographic origin, and above 12°C all isolates displayed atypical morphology that may have implications for proliferation of the fungus. This study demonstrates that small variations in temperature, consistent with those inherent of bat hibernacula, affect growth performance and physiology of G. destructans, which may influence temperature-dependent progression and severity of WNS in wild bats.

  16. Temperature dependence of magnetic properties of Cu80Co19Ni1 thin microwires

    International Nuclear Information System (INIS)

    Garcia, C.; Zhukov, A.; Zhukova, V.; Larin, V.; Gonzalez, J.; Val, J.J. del; Knobel, M.

    2007-01-01

    In the present work, we report the studies of temperature dependence of magnetic properties in thin microwires with composition Cu 80 Co 19 Ni 1 . An extensive study of structural and magnetic characterization was realized. The structure was observed using X-ray diffraction with CuK α radiation. The magnetic measurements were carried out using a SQUID at temperatures between 5 and 300 K. The as-prepared Cu 80 Co 19 Ni 1 microwire presents a coercivity of about 80 Oe. The variation of the coercivity and remanent magnetization at 5-300 K were obtained from the hysteresis loops. From the difference of the ZFC and FC curves below T=100 K, we can assume the presence of small superparamagnetic grains embedded in the Cu matrix. Those superparamagnetic grains should be blocked at temperatures below the maximum of the magnetization observed below 50 K. The measurements show an unusual temperature dependence of the coercive field, consequence of a coexistence of blocked and unblocked particles, and the typical decreasing behaviour of the remanence increasing temperature

  17. POINT 2012: ENDF/B-VII.1 Final Temperature Dependent Cross Section Library

    International Nuclear Information System (INIS)

    Cullen, D.E.

    2012-01-01

    This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF/B [R1]. In each case I have used my personal computer at home and publicly available data and codes: (1) publicly available nuclear data (the current ENDF/B data, available on-line at the National Nuclear Data Center, Brookhaven National Laboratory, http://www.nndc.bnl.gov/) and, (2) publicly available computer codes (the current PREPRO codes, available on-line at the Nuclear Data Section, IAEA, Vienna, Austria, http://www-nds.iaea.or.at/ndspub/endf/prepro/) and, (3) My own personal computer located in my home. I have used these in combination to produce the temperature dependent cross sections used in applications and described in this report. I should mention that today anyone with a personal computer can produce these results: by its very nature I consider this data to be born in the public domain.

  18. DEVELOPMENT OF GREEN’S FUNCTION APPROACH CONSIDERING TEMPERATURE-DEPENDENT MATERIAL PROPERTIES AND ITS APPLICATION

    Directory of Open Access Journals (Sweden)

    HAN-OK KO

    2014-02-01

    Full Text Available About 40% of reactors in the world are being operated beyond design life or are approaching the end of their life cycle. During long-term operation, various degradation mechanisms occur. Fatigue caused by alternating operational stresses in terms of temperature or pressure change is an important damage mechanism in continued operation of nuclear power plants. To monitor the fatigue damage of components, Fatigue Monitoring System (FMS has been installed. Most FMSs have used Green's Function Approach (GFA to calculate the thermal stresses rapidly. However, if temperature-dependent material properties are used in a detailed FEM, there is a maximum peak stress discrepancy between a conventional GFA and a detailed FEM because constant material properties are used in a conventional method. Therefore, if a conventional method is used in the fatigue evaluation, thermal stresses for various operating cycles may be calculated incorrectly and it may lead to an unreliable estimation. So, in this paper, the modified GFA which can consider temperature-dependent material properties is proposed by using an artificial neural network and weight factor. To verify the proposed method, thermal stresses by the new method are compared with those by FEM. Finally, pros and cons of the new method as well as technical findings from the assessment are discussed.

  19. Temperature dependence of electroluminescent emission from (ZnS : Cu, Mn(H)) type luminophors

    International Nuclear Information System (INIS)

    Singh, L.K.

    1986-04-01

    The dependence of electroluminescent yield on temperature for hydrogen coactivated (ZnS : Cu, Mn) type triple band emitting phosphors has been investigated at various temperatures under varied operating conditions of excitations. The influence of the excitation frequency, voltage and of emission wavelengths for the electroluminescent characteristics has also been observed on temperature variations. The results have also been studied for temperature dependences of emitting brightness under the excitation by UV-radiations of 3650 A.U. and a comparison is made between temperature dependent characteristics of E.L. and PL-brightness of emissions. It was observed that, as usual, brightness maxima on temperature scale varied with alteration of operating electric fields regarding frequency and voltage both for blue, green and yellow orange emissions of attempted samples. The important thing which is observed here, is that with regards the temperature EL-intensities vary respectively for all respective emissions but emission peaks are not shifted on wave-length scale. This no shift is due to the narrowly and compactly distributed coactivator levels of hydrogen. (author)

  20. Temperature dependence of optical properties in Nd/Cr:YAG materials

    International Nuclear Information System (INIS)

    Honda, Yoshiyuki; Motokoshi, Shinji; Jitsuno, Takahisa; Miyanaga, Noriaki; Fujioka, Kana; Nakatsuka, Masahiro; Yoshida, Minoru

    2014-01-01

    The energy transfer from Cr 3+ to Nd 3+ for Nd/Cr:YAG (Nd: 1.0%, Cr: 2.0%) materials was investigated by measuring the temperature dependences of fluorescence characteristics. The fluorescence intensity of Nd 3+ increased with temperature owing to enhancement of the absorption coefficient of Cr 3+ . The energy transfer efficiency was constant from 77 to 450 K. The energy transfer time decreased with increasing temperature. -- Highlights: • We investigate the energy transfer from Cr 3+ to Nd 3+ in Nd/Cr:YAG materials by measuring the temperature dependence of fluorescence characteristics. • The fluorescence intensity of Nd 3+ increased with temperature owing to enhancement of the absorption coefficient of Cr 3+ . • The energy transfer efficiency was constant from 77 to 450 K. • The energy transfer time decreased with increasing temperature. • Nd/Cr:YAG ceramics pumped by a flash lamp would not only provide high conversion efficiency, but can also be expected to function as an effective laser operating at high temperature

  1. Temperature-dependent photoluminescence of water-soluble quantum dots for a bioprobe

    International Nuclear Information System (INIS)

    Liu Tiancai; Huang Zhenli; Wang Haiqiao; Wang Jianhao; Li Xiuqing; Zhao Yuandi; Luo Qingming

    2006-01-01

    The photoluminescence of water-soluble CdSe/ZnS core/shell quantum dots is found to be temperature-dependent: as temperature arising from 280 K to 351 K, the photoluminescence declines with emission peak shifting towards the red at a rate of ∼0.11 nm K -1 . And the studies show that the photoluminescence of water-soluble CdSe/ZnS quantum dots with core capped by a thinner ZnS shell is more sensitive to temperature than that of ones with core capped by a thicker one. That is, with 50% decrement of the quantum yield the temperature of the former need to arise from 280 K to 295 K, while the latter requires much higher temperature (315.6 K), which means that the integrality of shell coverage is a very important factor on temperature-sensitivity to for the photoluminescence of water-soluble CdSe/ZnS quantum dots. Moreover, it is found that the water-soluble CdSe quantum dots with different core sizes, whose cores are capped by thicker ZnS shells, possess almost the same sensitivity to the temperature. All of the studies about photoluminescence temperature-dependence of water-soluble CdSe/ZnS core/shell quantum dots show an indispensable proof for their applications in life science

  2. Temperature-Dependent Rate Coefficients for the Reaction of CH2OO with Hydrogen Sulfide.

    Science.gov (United States)

    Smith, Mica C; Chao, Wen; Kumar, Manoj; Francisco, Joseph S; Takahashi, Kaito; Lin, Jim Jr-Min

    2017-02-09

    The reaction of the simplest Criegee intermediate CH 2 OO with hydrogen sulfide was measured with transient UV absorption spectroscopy in a temperature-controlled flow reactor, and bimolecular rate coefficients were obtained from 278 to 318 K and from 100 to 500 Torr. The average rate coefficient at 298 K and 100 Torr was (1.7 ± 0.2) × 10 -13 cm 3 s -1 . The reaction was found to be independent of pressure and exhibited a weak negative temperature dependence. Ab initio quantum chemistry calculations of the temperature-dependent reaction rate coefficient at the QCISD(T)/CBS level are in reasonable agreement with the experiment. The reaction of CH 2 OO with H 2 S is 2-3 orders of magnitude faster than the reaction with H 2 O monomer. Though rates of CH 2 OO scavenging by water vapor under atmospheric conditions are primarily controlled by the reaction with water dimer, the H 2 S loss pathway will be dominated by the reaction with monomer. The agreement between experiment and theory for the CH 2 OO + H 2 S reaction lends credence to theoretical descriptions of other Criegee intermediate reactions that cannot easily be probed experimentally.

  3. Investigation of temperature dependent barrier height of Au/ZnO/Si schottky diodes

    International Nuclear Information System (INIS)

    Asghar, M.; Mahmood, K.; Rabia, S.; BM, S.; Shahid, M. Y.; Hasan, M. A.

    2013-01-01

    In this study, temperature dependent current-voltage (I-V) measurements have been performed to investigate the inhomogeneity in the temperature dependent barrier heights of Au/ZnO/Si Schottky barrier diode in the temperature range 150 - 400K. The room temperature values for ideality factor and barrier height were found to be 2.9 and 0.60 eV respectively indicating the inhomogenity in the barrier heights of grown samples. The Richardson plot and ideality factor verses barrier height graph were also drawn to verified the discontinuity between Au and ZnO. This barrier height inhomogenity was explained by applying Gaussian distribution model. The extrapolation of the linear Fap (n) plot to n= 1 has given a homogeneous barrier height of approximately 1.1 eV. Fap versus 1/T plot was drawn to obtain the values of mean barrier height for Au/ZnO/Si Schottky diode (1.1 eV) and standard deviation(ds) (0.02 V) at zero bais. (author)

  4. Investigation of temperature dependent barrier height of Au/ZnO/Si schottky diodes

    International Nuclear Information System (INIS)

    Asghar, M; Mahmood, K; Rabia, S; M, Samaa B; Shahid, M Y; Hasan, M A

    2014-01-01

    In this study, temperature dependent current-voltage (I-V) measurements have been performed to investigate the inhomogeneity in the temperature dependent barrier heights of Au/ZnO/Si Schottky barrier diode in the temperature range 150 – 400K. The room temperature values for ideality factor and barrier height were found to be 2.9 and 0.60 eV respectively indicating the inhomogenity in the barrier heights of grown samples. The Richardson plot and ideality factor verses barrier height graph were also drawn to verified the discontinuity between Au and ZnO. This barrier height inhomogenity was explained by applying Gaussian distribution model. The extrapolation of the linear Φ ap (n) plot to n= 1 has given a homogeneous barrier height of approximately 1.1 eV. Φ ap versus 1/T plot was drawn to obtain the values of mean barrier height for Au/ZnO/Si Schottky diode (1.1 eV) and standard deviation(δ s ) (0.02 V) at zero bais

  5. Temperature dependence of the current in Schottky-barrier source-gated transistors

    Science.gov (United States)

    Sporea, R. A.; Overy, M.; Shannon, J. M.; Silva, S. R. P.

    2015-05-01

    The temperature dependence of the drain current is an important parameter in thin-film transistors. In this paper, we propose that in source-gated transistors (SGTs), this temperature dependence can be controlled and tuned by varying the length of the source electrode. SGTs comprise a reverse biased potential barrier at the source which controls the current. As a result, a large activation energy for the drain current may be present which, although useful in specific temperature sensing applications, is in general deleterious in many circuit functions. With support from numerical simulations with Silvaco Atlas, we describe how increasing the length of the source electrode can be used to reduce the activation energy of SGT drain current, while maintaining the defining characteristics of SGTs: low saturation voltage, high output impedance in saturation, and tolerance to geometry variations. In this study, we apply the dual current injection modes to obtain drain currents with high and low activation energies and propose mechanisms for their exploitation in future large-area integrated circuit designs.

  6. Temperature dependence of energy-transducing functions and inhibitor sensitivity in chloroplasts

    Energy Technology Data Exchange (ETDEWEB)

    Schuurmans, J.J.; Veerman, E.C.I.; Francke, J.A.; Torres-Pereira, J.M.G.; Kraayenhof, R.

    1984-01-01

    A comparative analysis of the temperature dependence of energy-transducing reactions in spinach (Spinacia oleracea) chloroplasts and their sensitivity for uncouplers and energy-transfer inhibitors at different temperatures is presented. Arrhenius plots reveal two groups of transitions, around 19/sup 0/C and around 12/sup 0/C. Activities that show transitions around 19/sup 0/C include linear electron flow from water to ferricyanide, its coupled photophosphorylation, the dark-release of the fluorescent probe atebrin, and the slow component of the 515 nm (carotenoid) absorbance decay after a flash. The transitions around 12/sup 0/C are observed with pyocyanine-mediated cyclic photophosphorylation, light- and dithioerythritol-activated ATP hydrolysis, the dark-release of protons, and the fast 515 nm decay component. It is suggested that both groups of temperature transitions are determined by proton displacements in different domains of the exposed thylakoid membranes. The effects of various uncouplers and an energy-transfer inhibitor are temperature dependent. Some uncouplers also show a different relative inhibition of proton uptake and ATP synthesis at lower temperatures. The efficiency of energy transduction (ATP/e/sub 3/) varied with temperature and was optimal around 10/sup 0/C.

  7. Frequency and Temperature Dependent Dielectric Properties of Free-standing Strontium Titanate Thin Films.

    Science.gov (United States)

    Dalberth, Mark J.; Stauber, Renaud E.; Anderson, Britt; Price, John C.; Rogers, Charles T.

    1998-03-01

    We will report on the frequency and temperature dependence of the complex dielectric function of free-standing strontium titanate (STO) films. STO is an incipient ferroelectric with electric-field tunable dielectric properties of utility in microwave electronics. The films are grown epitaxially via pulsed laser deposition on a variety of substrates, including lanthanum aluminate (LAO), neodymium gallate (NGO), and STO. An initial film of yttrium barium cuprate (YBCO) is grown on the substrate, followed by deposition of the STO layer. Following deposition, the sacrificial YBCO layer is chemically etched away in dilute nitric acid, leaving the substrate and a released, free-standing STO film. Coplanar capacitor structures fabricated on the released films allow us to measure the dielectric response. We observe a peak dielectric function in excess of 5000 at 35K, change in dielectric constant of over a factor of 8 for 10Volt/micron electric fields, and temperature dependence above 50K that is very similar to bulk material. The dielectric loss shows two peaks, each with a thermally activated behavior, apparently arising from two types of polar defects. We will discuss the correlation between dielectric properties, growth conditions, and strain in the free-standing STO films.

  8. Temperature Dependence of Emission Properties of Self-Assembled InGaN Quantum Dots

    International Nuclear Information System (INIS)

    Zhao Wan-Ru; Zhang Jiang-Yong; Zhang Bao-Ping; Weng Guo-En; Liang Ming-Ming; Li Zeng-Cheng; Liu Jian-Ping

    2014-01-01

    Emission properties of self-assembled green-emitting InGaN quantum dots (QDs) grown on sapphire substrates by using metal organic chemical vapor deposition are studied by temperature-dependent photoluminescence (PL) measurements. As temperature increases (15–300 K), the PL peak energy shows an anomalous V-shaped (redshift—blueshift) variation instead of an S-shaped (redshift—blueshift—redshift) variation, as observed typically in green-emitting InGaN/GaN multi-quantum wells (MQWs). The PL full width at half maximum (FWHM) also shows a V-shaped (decrease—increase) variation. The temperature dependence of the PL peak energy and FWHM of QDs are well explained by a model similar to MQWs, in which carriers transferring in localized states play an important role, while the confinement energy of localized states in the QDs is significantly larger than that in MQWs. By analyzing the integrated PL intensity, the larger confinement energy of localized states in the QDs is estimated to be 105.9 meV, which is well explained by taking into account the band-gap shrinkage and carrier thermalization with temperature. It is also found that the nonradiative combination centers in QD samples are much less than those in QW samples with the same In content

  9. Temperature dependent mobility measurements of alkali earth ions in superfluid helium

    Science.gov (United States)

    Putlitz, Gisbert Zu; Baumann, I.; Foerste, M.; Jungmann, K.; Riediger, O.; Tabbert, B.; Wiebe, J.; Zühlke, C.

    1998-05-01

    Mobility measurements of impurity ions in superfluid helium are reported. Alkali earth ions were produced with a laser sputtering technique and were drawn inside the liquid by an electric field. The experiments were carried out in the temperature region from 1.27 up to 1.66 K. The temperature dependence of the mobility of Be^+-ions (measured here for the first time) differs from that of the other alkali earth ions Mg^+, Ca^+, Sr^+ and Ba^+, but behaves similar to that of He^+ (M. Foerste, H. Günther, O. Riediger, J. Wiebe, G. zu Putlitz, Z. Phys. B) 104, 317 (1997). Theories of Atkins (A. Atkins, Phys. Rev.) 116, 1339 (1959) and Cole (M.W. Cole, R.A. Bachmann Phys. Rev. B) 15, 1388 (1977) predict a different defect structure for He^+ and the alkali earth ions: the helium ion is assumed to form a snowball like structure whereas for the alkali earth ions a bubble structure is assumed. If the temperature dependence is a characteristic feature for the different structures, then it seems likely that the Be^+ ion builds a snowball like structure.

  10. Temperature dependence of CO2-enhanced primary production in the European Arctic Ocean

    KAUST Repository

    Holding, J. M.

    2015-08-31

    The Arctic Ocean is warming at two to three times the global rate1 and is perceived to be a bellwether for ocean acidification2, 3. Increased CO2 concentrations are expected to have a fertilization effect on marine autotrophs4, and higher temperatures should lead to increased rates of planktonic primary production5. Yet, simultaneous assessment of warming and increased CO2 on primary production in the Arctic has not been conducted. Here we test the expectation that CO2-enhanced gross primary production (GPP) may be temperature dependent, using data from several oceanographic cruises and experiments from both spring and summer in the European sector of the Arctic Ocean. Results confirm that CO2 enhances GPP (by a factor of up to ten) over a range of 145–2,099 μatm; however, the greatest effects are observed only at lower temperatures and are constrained by nutrient and light availability to the spring period. The temperature dependence of CO2-enhanced primary production has significant implications for metabolic balance in a warmer, CO2-enriched Arctic Ocean in the future. In particular, it indicates that a twofold increase in primary production during the spring is likely in the Arctic.

  11. Temperature Dependence on Density, Viscosity, and Electrical Conductivity of Ionic Liquid 1-Ethyl-3-Methylimidazolium Fluoride

    Directory of Open Access Journals (Sweden)

    Fengguo Liu

    2018-03-01

    Full Text Available Ionic liquids are considered environmentally friendly media for various industrial applications. Basic data on physicochemical properties are significant for a new material, in terms of developing its potential applications. In this work, 1-ethyl-3-methylimidazolium fluoride ([EMIm]F ionic liquid was synthesized via an anion metathesis process. Physical properties including the density, viscosity, electrical conductivity, and thermal stability of the product were measured. The results show that the density of [EMIm]F decreases linearly with temperature increases, while dynamic viscosity decreases rapidly below 320 K and the temperature dependence of electrical conductivity is in accordance with the VFT (Vogel–Fulcher–Tammann equation. The temperature dependence of the density, conductivity, and viscosity of [EMIm]F can be expressed via the following equations: ρ = 1.516 − 1.22 × 10−3 T, σm = 4417.1exp[−953.17/(T − 166.65] and η = 2.07 × 10−7exp(−5.39 × 104/T, respectively. [EMIm]F exhibited no clear melting point. However, its glass transition point and decomposition temperature are −71.3 °C and 135 °C, respectively.

  12. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Delimitis, A. [Chemical Process Engineering Research Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 57001 Thermi, Thessaloniki (Greece); Poulopoulos, P. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Materials Science Department, University of Patras, 26504 Patras (Greece); Fumagalli, P. [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Politis, C. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  13. POINT 2012: ENDF/B-VII.1 Final Temperature Dependent Cross Section Library

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, D E

    2012-02-26

    This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF/B [R1]. In each case I have used my personal computer at home and publicly available data and codes: (1) publicly available nuclear data (the current ENDF/B data, available on-line at the National Nuclear Data Center, Brookhaven National Laboratory, http://www.nndc.bnl.gov/) and, (2) publicly available computer codes (the current PREPRO codes, available on-line at the Nuclear Data Section, IAEA, Vienna, Austria, http://www-nds.iaea.or.at/ndspub/endf/prepro/) and, (3) My own personal computer located in my home. I have used these in combination to produce the temperature dependent cross sections used in applications and described in this report. I should mention that today anyone with a personal computer can produce these results: by its very nature I consider this data to be born in the public domain.

  14. Ceramic/Metal Composites with Positive Temperature Dependence of Thermal Conductivity

    International Nuclear Information System (INIS)

    Li Jianhui; Yu Qi; Sun Wei; Zhang Rui; Wang Ke; Li Jingfeng; Ichigozaki, Daisuke

    2013-01-01

    Most materials show decreasing thermal conductivity with increasing temperature, but an opposite temperature dependence of thermal conductivity is required for some industrial applications. The present work was conducted with a motivation to develop composite materials with a positive temperature dependence of thermal conductivity. ZrO 2 / stainless steel powders (304L) composite, with 3% stearic acid, was prepared by normal sintering under the protecting of Ar after mixing by mechanical ball milling technique. With the 304L content increasing from 10% to 20%, the thermal conductivity values increased. For all samples, the thermal conductivity in the temperature range of room temperature to 700 °C decreased with temperature below 300 °C, and then began to increase. The increasing thermal conductivity of the composites (within the high temperature range was attributed to the difference of the thermal conductivity and thermal expansion coefficient between ZrO 2 ceramic and 304L stainless steel powders. Two simple models were also used to estimate the thermal conductivity of the composites, which were in good agreement with the experiment results.

  15. Temperature-dependent photoluminescence of water-soluble quantum dots for a bioprobe

    Energy Technology Data Exchange (ETDEWEB)

    Liu Tiancai [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Huang Zhenli [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang Haiqiao [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang Jianhao [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li Xiuqing [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zhao Yuandi [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)]. E-mail: zydi@mail.hust.edu.cn; Luo Qingming [Key Laboratory of Biomedical Photonics of Ministry of Education - Hubei Bioinformatics and Molecular Imaging Key Laboratory, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2006-02-10

    The photoluminescence of water-soluble CdSe/ZnS core/shell quantum dots is found to be temperature-dependent: as temperature arising from 280 K to 351 K, the photoluminescence declines with emission peak shifting towards the red at a rate of {approx}0.11 nm K{sup -1}. And the studies show that the photoluminescence of water-soluble CdSe/ZnS quantum dots with core capped by a thinner ZnS shell is more sensitive to temperature than that of ones with core capped by a thicker one. That is, with 50% decrement of the quantum yield the temperature of the former need to arise from 280 K to 295 K, while the latter requires much higher temperature (315.6 K), which means that the integrality of shell coverage is a very important factor on temperature-sensitivity to for the photoluminescence of water-soluble CdSe/ZnS quantum dots. Moreover, it is found that the water-soluble CdSe quantum dots with different core sizes, whose cores are capped by thicker ZnS shells, possess almost the same sensitivity to the temperature. All of the studies about photoluminescence temperature-dependence of water-soluble CdSe/ZnS core/shell quantum dots show an indispensable proof for their applications in life science.

  16. Temperature dependence of HU values for various water equivalent phantom materials

    International Nuclear Information System (INIS)

    Homolka, P.; Nowotny, R.; Gahleitner, A.

    2002-01-01

    The temperature dependence of water equivalent phantom materials used in radiotherapy and diagnostic imaging has been investigated. Samples of phantom materials based on epoxy resin, polyethylene, a polystyrene-polypropylene mixture and commercially available phantom materials (Solid Water TM , Gammex RMI and Plastic Water TM , Nuclear Associates) were scanned at temperatures from 15 to 40 deg. C and HU values determined. At a reference temperature of 20 deg. C materials optimized for CT applications give HU values close to zero while the commercial materials show an offset of 119.77 HU (Plastic Water) and 27.69 HU (Solid Water). Temperature dependence was lowest for epoxy-based materials (EPX-W: -0.23 HU deg. C -1 ; Solid Water: -0.25 HU deg. C -1 ) and highest for a polyethylene-based material (X0: -0.72 HU deg. C -1 ). A material based on a mixture of polystyrene and polypropylene (PSPP1: -0.27 HU deg. C -1 ) is comparable to epoxy-based materials and water (-0.29 HU deg. C -1 ). (author)

  17. Temperature dependence of the calibration factor of radon and radium determination in water samples by SSNTD

    CERN Document Server

    Hunyadi, I; Hakl, J; Baradacs, E; Dezso, Z

    1999-01-01

    The sensitivity of a sup 2 sup 2 sup 6 Ra determination method of water samples by SSNTD was measured as a function of storage temperature during exposure. The method is based on an etched track type radon monitor, which is closed into a gas permeable foil and is immersed in the water sample. The sample is sealed in a glass vessel and stored for an exposure time of 10-30 days. The sensitivity increased more than a factor of two when the storage temperature was raised from 2 deg. C to 30 deg. C. Temperature dependence of the partition coefficient of radon between water and air provides explanation for this dependence. For practical radio- analytical application the temperature dependence of the calibration factor is given by fitting the sensitivity data obtained by measuring sup 2 sup 2 sup 6 Ra standard solutions (in the activity concentration range of 0.1-48.5 kBq m sup - sup 3) at different storage temperatures.

  18. Peculiarities of the temperature dependences of trapped magnetic field in Y-HTSC ceramics

    International Nuclear Information System (INIS)

    Sukhanov, A.A.; Omel'chenko, V.I.

    2001-01-01

    The temperature dependence H t (T) of trapped magnetic field (TMF) in Y-HTSC ceramics are studied. For the fields-cooled trapping the H t (T) dependences coincide with the dependences of H t on trapping temperature T t . Both dependences fall off monotonously with increasing temperature, and for low fields they reach saturation as temperature is decreased. When the trapping is induced by the field pulse after zero cooling the H t (T t ) dependences show a maximum while the H t (T) curves drop monotonously with increase in temperature. In this case the rate of their dropping increases with decrease in pulse magnitude and the temperature of TMF vanishing decreases with T t and H. The results are discussed and it is shown that contrast to the Been model the theory based on the model of TMF in superconductive loops gives an adequate analytical description of the observed features of the temperature dependences of trapped magnetic field in the Y-HTSC ceramics

  19. NF3: UV Absorption Spectrum Temperature Dependence and the Atmospheric and Climate Forcing Implications

    Science.gov (United States)

    Papadimitriou, Vassileios C.; McGillen, Max R.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.

    2013-01-01

    Nitrogen trifluoride (NF3) is an atmospherically persistent greenhouse gas that is primarily removed by UV photolysis and reaction with O((sup 1)D) atoms. In this work, the NF3 gas-phase UV absorption spectrum, sigma(delta,T), was measured at 16 wavelengths between 184.95 and 250 nm at temperatures between 212 and 296 K. A significant spectrum temperature dependence was observed in the wavelength region most relevant to atmospheric photolysis (200-220 nm) with a decrease in sigma(210 nm,T) of approximately 45 percent between 296 and 212 K. Atmospheric photolysis rates and global annually averaged lifetimes of NF3 were calculated using the Goddard Space Flight Center 2-D model and the sigma(delta,T) parameterization developed in this work. Including the UV absorption spectrum temperature dependence increased the stratospheric photolysis lifetime from 610 to 762 years and the total global lifetime from 484 to 585 years; the NF3 global warming potentials on the 20-, 100-, and 500-year time horizons increased less than 0.3, 1.1, and 6.5 percent to 13,300, 17,700, and 19,700, respectively.

  20. Inferring the temperature dependence of Beremin cleavage model parameters from the Master Curve

    International Nuclear Information System (INIS)

    Cao Yupeng; Hui Hu; Wang Guozhen; Xuan Fuzhen

    2011-01-01

    Research highlights: → Temperature dependence of Beremin model parameters is inferred by Master Curve approach. → Weibull modulus decreases while Weibull stress scale parameter increases with increasing the temperature. → Estimation of Weibull stress parameters in terms of small amounts of specimens leads to a considerable uncertainty. - Abstract: The temperature dependence of Beremin model parameters in the ductile-to-brittle transition region was addressed by employing the Master Curve. Monte Carlo simulation was performed to produce a large number of 1T fracture toughness data randomly drawn from the scatter band at a temperature of interest and thus to determine Beremin model parameters. In terms of the experimental data of a C-Mn steel (the 16MnR steel in China), results revealed that the Weibull modulus, m, decreases with temperature over the lower transition range and remains a constant in the lower-to-mid transition region. The Weibull scale parameter, σ u , increases with temperature over the temperature range of investigated. A small sample may lead to a considerable uncertainty in estimates of the Weibull stress parameters. However, no significant difference was observed for the average of Weibull stress parameters from different sample sizes.

  1. l-Proline and RNA Duplex m-Value Temperature Dependence.

    Science.gov (United States)

    Schwinefus, Jeffrey J; Baka, Nadia L; Modi, Kalpit; Billmeyer, Kaylyn N; Lu, Shutian; Haase, Lucas R; Menssen, Ryan J

    2017-08-03

    The temperature dependence of l-proline interactions with the RNA dodecamer duplex surface exposed after unfolding was quantified using thermal and isothermal titration denaturation monitored by uv-absorbance. The m-value quantifying proline interactions with the RNA duplex surface area exposed after unfolding was measured using RNA duplexes with GC content ranging between 17 and 83%. The m-values from thermal denaturation decreased with increasing GC content signifying increasingly favorable proline interactions with the exposed RNA surface area. However, m-values from isothermal titration denaturation at 25.0 °C were independent of GC content and less negative than those from thermal denaturation. The m-value from isothermal titration denaturation for a 50% GC RNA duplex decreased (became more negative) as the temperature increased and was in nearly exact agreement with the m-value from thermal denaturation. Since RNA duplex transition temperatures increased with GC content, the more favorable proline interactions with the high GC content duplex surface area observed from thermal denaturation resulted from the temperature dependence of proline interactions rather than the RNA surface chemical composition. The enthalpy contribution to the m-value was positive and small (indicating a slight increase in duplex unfolding enthalpy with proline) while the entropic contribution to the m-value was positive and increased with temperature. Our results will facilitate proline's use as a probe of solvent accessible surface area changes during biochemical reactions at different reaction temperatures.

  2. Optical detection of CO and CO2 temperature dependent desorption from carbon nanotube clusters

    International Nuclear Information System (INIS)

    Chistiakova, M V; Armani, A M

    2014-01-01

    The development of new materials relies on high precision methods to quantify adsorption/desorption of gases from surfaces. One commonly used approach is temperature programmed desorption spectroscopy. While this approach is very accurate, it requires complex instrumentation, and it is limited to performing experiments under high vacuum, thus restricting experimental scope. An alternative approach is to integrate the surface of interest directly onto a detector face, creating an active substrate. One surface that has applications in numerous areas is the carbon nanotube (CNT). As such, an active substrate that integrates a CNT surface on a sensor and is able to perform measurements in ambient environments will have significant impact. In the present work, we have developed an active substrate that combines an optical sensor with a CNT cluster substrate. The optical sensor is able to accurately probe the temperature dependent desorption of carbon monoxide and carbon dioxide gases from the CNT cluster surface. This active substrate will enable a wide range of temperature dependent desorption measurements to be performed from a scientifically interesting material system. (paper)

  3. On the temperature dependence of H-U{sub iso} in the riding hydrogen model

    Energy Technology Data Exchange (ETDEWEB)

    Lübben, Jens; Volkmann, Christian [Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany); Grabowsky, Simon [School of Chemistry and Biochemistry, Stirling Highway 35, WA-6009 Crawley (Australia); Edwards, Alison [Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Morgenroth, Wolfgang [Institut für Geowissenschaften, Abteilung Kristallographie, Goethe-Universität, Altenhöferallee 1, 60438 Frankfurt am Main (Germany); Fabbiani, Francesca P. A. [GZG, Abteilung Kristallographie, Georg-August Universität, Goldschmidtstrasse 1, 37077 Göttingen (Germany); Sheldrick, George M. [Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany); Dittrich, Birger, E-mail: birger.dittrich@chemie.uni-hamburg.de [Institut für Anorganische und Angewandte Chemie, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Institut für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077 Göttingen (Germany)

    2014-07-01

    The temperature dependence of hydrogen U{sub iso} and parent U{sub eq} in the riding hydrogen model is investigated by neutron diffraction, aspherical-atom refinements and QM/MM and MO/MO cluster calculations. Fixed values of 1.2 or 1.5 appear to be underestimated, especially at temperatures below 100 K. The temperature dependence of H-U{sub iso} in N-acetyl-l-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-U{sub iso} below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found.

  4. On the temperature dependence of H-Uiso in the riding hydrogen model

    International Nuclear Information System (INIS)

    Lübben, Jens; Volkmann, Christian; Grabowsky, Simon; Edwards, Alison; Morgenroth, Wolfgang; Fabbiani, Francesca P. A.; Sheldrick, George M.; Dittrich, Birger

    2014-01-01

    The temperature dependence of hydrogen U iso and parent U eq in the riding hydrogen model is investigated by neutron diffraction, aspherical-atom refinements and QM/MM and MO/MO cluster calculations. Fixed values of 1.2 or 1.5 appear to be underestimated, especially at temperatures below 100 K. The temperature dependence of H-U iso in N-acetyl-l-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-U iso below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found

  5. Temperature dependence of the interband critical points of bulk Ge and strained Ge on Si

    Science.gov (United States)

    Fernando, Nalin S.; Nunley, T. Nathan; Ghosh, Ayana; Nelson, Cayla M.; Cooke, Jacqueline A.; Medina, Amber A.; Zollner, Stefan; Xu, Chi; Menendez, Jose; Kouvetakis, John

    2017-11-01

    Epitaxial Ge layers on a Si substrate experience a tensile biaxial stress due to the difference between the thermal expansion coefficients of the Ge epilayer and the Si substrate, which can be measured using asymmetric X-ray diffraction reciprocal space maps. This stress depends on temperature and affects the band structure, interband critical points, and optical spectra. This manuscripts reports careful measurements of the temperature dependence of the dielectric function and the interband critical point parameters of bulk Ge and Ge epilayers on Si using spectroscopic ellipsometry from 80 to 780 K and from 0.8 to 6.5 eV. The authors find a temperature-dependent redshift of the E1 and E1 + Δ1 critical points in Ge on Si (relative to bulk Ge). This redshift can be described well with a model based on thermal expansion coefficients, continuum elasticity theory, and the deformation potential theory for interband transitions. The interband transitions leading to E0‧ and E2 critical points have lower symmetry and therefore are not affected by the stress.

  6. A Rigorous Temperature-Dependent Stochastic Modelling and Testing for MEMS-Based Inertial Sensor Errors

    Directory of Open Access Journals (Sweden)

    Spiros Pagiatakis

    2009-10-01

    Full Text Available In this paper, we examine the effect of changing the temperature points on MEMS-based inertial sensor random error. We collect static data under different temperature points using a MEMS-based inertial sensor mounted inside a thermal chamber. Rigorous stochastic models, namely Autoregressive-based Gauss-Markov (AR-based GM models are developed to describe the random error behaviour. The proposed AR-based GM model is initially applied to short stationary inertial data to develop the stochastic model parameters (correlation times. It is shown that the stochastic model parameters of a MEMS-based inertial unit, namely the ADIS16364, are temperature dependent. In addition, field kinematic test data collected at about 17 °C are used to test the performance of the stochastic models at different temperature points in the filtering stage using Unscented Kalman Filter (UKF. It is shown that the stochastic model developed at 20 °C provides a more accurate inertial navigation solution than the ones obtained from the stochastic models developed at −40 °C, −20 °C, 0 °C, +40 °C, and +60 °C. The temperature dependence of the stochastic model is significant and should be considered at all times to obtain optimal navigation solution for MEMS-based INS/GPS integration.

  7. A Rigorous Temperature-Dependent Stochastic Modelling and Testing for MEMS-Based Inertial Sensor Errors.

    Science.gov (United States)

    El-Diasty, Mohammed; Pagiatakis, Spiros

    2009-01-01

    In this paper, we examine the effect of changing the temperature points on MEMS-based inertial sensor random error. We collect static data under different temperature points using a MEMS-based inertial sensor mounted inside a thermal chamber. Rigorous stochastic models, namely Autoregressive-based Gauss-Markov (AR-based GM) models are developed to describe the random error behaviour. The proposed AR-based GM model is initially applied to short stationary inertial data to develop the stochastic model parameters (correlation times). It is shown that the stochastic model parameters of a MEMS-based inertial unit, namely the ADIS16364, are temperature dependent. In addition, field kinematic test data collected at about 17 °C are used to test the performance of the stochastic models at different temperature points in the filtering stage using Unscented Kalman Filter (UKF). It is shown that the stochastic model developed at 20 °C provides a more accurate inertial navigation solution than the ones obtained from the stochastic models developed at -40 °C, -20 °C, 0 °C, +40 °C, and +60 °C. The temperature dependence of the stochastic model is significant and should be considered at all times to obtain optimal navigation solution for MEMS-based INS/GPS integration.

  8. Temperature dependence of positron annihilation parameters in Tl-Ba-Ca-Cu-O superconductors

    International Nuclear Information System (INIS)

    Sundar, C.S.; Bharathi, A.; Ching, W.Y.; Jean, Y.C.; Hor, P.H.; Meng, R.L.; Huang, Z.J.; Chu, C.W.

    1990-01-01

    The results of positron lifetime and Doppler broadened line-shape parameter measurements as a function of temperature, across T c , in the Tl-Ba-Ca-Cu-O superconductors are presented. The bulk lifetime in the normal state is found to decrease with the increase in the number of CuO 2 layers. Different temperature dependencies of the annihilation parameters are observed in the various Tl systems containing different numbers of CuO 2 layers. In the Tl 2 Ba 2 Ca 2 Cu 3 O 10 system, an increase in lifetime is observed below T c , whereas in Tl 2 Ba 2 CaCu 2 O 8 , a decrease in lifetime is seen below T c . In the Tl 2 Ba 2 CuO 6 system, the lifetime is observed to be temperature independent. The different temperature variations of positron annihilation parameters are discussed in the light of the positron density distribution, obtained with use of the results of the self-consistent orthogonalized linear combination of atomic orbitals band-structure calculations. It is argued that the different temperature dependencies of the annihilation parameters is related to the positron density distribution within the unit cell and arise due to local charge transfer in the vicinity of the CuO 2 layer in the superconducting state

  9. Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach

    International Nuclear Information System (INIS)

    Liu Guibin; Liu Banggui

    2009-01-01

    We use a Green's function method to study the temperature-dependent average moment and magnetic phase-transition temperature of the striped antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of FeAs-based superconductors. We consider the nearest and the next-nearest couplings in the FeAs layer, and the nearest coupling for inter-layer spin interaction. The dependence of the transition temperature T N and the zero-temperature average spin on the interaction constants is investigated. We obtain an analytical expression for T N and determine our temperature-dependent average spin from zero temperature to T N in terms of unified self-consistent equations. For LaFeAsO, we obtain a reasonable estimation of the coupling interactions with the experimental transition temperature T N = 138 K. Our results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling is essential for the existence of a non-zero T N , and the many-body AFM fluctuations reduce substantially the low-temperature magnetic moment per Fe towards the experimental value. Our Green's function approach can be used for other FeAs-based parent compounds and these results should be useful to understand the physical properties of FeAs-based superconductors.

  10. Low-temperature dependence of yielding in AISI 316 stainless steels

    International Nuclear Information System (INIS)

    Tobler, R.L.; Reed, R.P.

    1981-01-01

    Tensile tests at temperatures between 323 and 4 K were performed on one heat of AISI 316 austenitic stainless steel having the composition Fe-17.34Cr-12.17Ni-1.55Mn-2.16Mo-0.051C. The temperature dependences of the yield and flow strengths at plastic strain increments from 0.2 to 3.65% are analyzed. At the yield strain (0.2%), no body-centered cubic (bcc) martensite phase transformation is detected. At higher strains (approx.3.2 +- 0.6%), bcc martensite forms from the parent austenite phase at test temperatures below 190 K, but there are no discontinuities in the temperature dependence of flow strength. A review of data available for three heats of AISI 316 at temperatures between 973 and 4 K reveals that deviations from thermally activated plastic flow theory occur at temperatures below 175 K, apparently depending on heat-to-heat compositional variations. Grain size and magnetic transition effects on the yield strength are discussed

  11. Temperature dependence of immunoreactions using shear horizontal surface acoustic wave immunosensors

    Science.gov (United States)

    Kogai, Takashi; Yatsuda, Hiromi; Kondoh, Jun

    2017-07-01

    In this paper, the temperature dependence of immunoreactions, which are antibody-antigen reactions, on a shear horizontal surface acoustic wave (SH-SAW) immunosensor is described. The immunosensor is based on a reflection-type delay line on a 36° Y-cut 90° X-propagation quartz substrate, where the delay line is composed of a floating electrode unidirectional transducer (FEUDT), a grating reflector, and a sensing area between them. In order to evaluate the temperature dependence of immunoreactions, human serum albumin (HSA) antigen-antibody reactions are investigated. The SH-SAW immunosensor chip is placed in a thermostatic chamber and the changes in the SH-SAW velocity resulting from the immunoreactions are measured at different temperatures. As a result, it is observed that the HSA immunoreactions are influenced by the ambient temperature and that higher temperatures provide more active reactions. In order to analyze the immunoreactions, an analytical approach using an exponential fitting method for changes in SH-SAW velocity is employed.

  12. Temperature-dependent elastic properties of Ti{sub 1−x}Al{sub x}N alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shulumba, Nina [Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Functional Materials, Saarland University, D-66123 Saarbrücken (Germany); Hellman, Olle [Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125 (United States); Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Rogström, Lina; Raza, Zamaan; Tasnádi, Ferenc; Odén, Magnus [Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Abrikosov, Igor A. [Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Materials Modeling and Development Laboratory, NUST “MISIS,” 119049 Moscow (Russian Federation); LACOMAS Laboratory, Tomsk State University, 634050 Tomsk (Russian Federation)

    2015-12-07

    Ti{sub 1−x}Al{sub x}N is a technologically important alloy that undergoes a process of high temperature age-hardening that is strongly influenced by its elastic properties. We have performed first principles calculations of the elastic constants and anisotropy using the symmetry imposed force constant temperature dependent effective potential method, which include lattice vibrations and therefore the effects of temperature, including thermal expansion and intrinsic anharmonicity. These are compared with in situ high temperature x-ray diffraction measurements of the lattice parameter. We show that anharmonic effects are crucial to the recovery of finite temperature elasticity. The effects of thermal expansion and intrinsic anharmonicity on the elastic constants are of the same order, and cannot be considered separately. Furthermore, the effect of thermal expansion on elastic constants is such that the volume change induced by zero point motion has a significant effect. For TiAlN, the elastic constants soften non-uniformly with temperature: C{sub 11} decreases substantially when the temperature increases for all compositions, resulting in an increased anisotropy. These findings suggest that an increased Al content and annealing at higher temperatures will result in a harder alloy.

  13. Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols

    International Nuclear Information System (INIS)

    Lin Mingzhang; Mostafavi, M.; Lampre, I.; Muroya, Y.; Katsumura, Y.

    2007-01-01

    The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol -1 ·m 2 for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures. (authors)

  14. On the nature and temperature dependence of the fundamental band gap of In{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Irmscher, K.; Naumann, M.; Pietsch, M.; Galazka, Z.; Uecker, R.; Schulz, T.; Schewski, R.; Albrecht, M.; Fornari, R. [Leibniz-Institut fuer Kristallzuechtung, Berlin (Germany)

    2014-01-15

    The onset of optical absorption in In{sub 2}O{sub 3} at about 2.7 eV is investigated by transmission spectroscopy of single crystals grown from the melt. This absorption is not defect related but is due to the fundamental band gap of In{sub 2}O{sub 3}. The corresponding spectral dependence of the absorption coefficient is determined up to α = 2500 cm{sup -1} at a photon energy hν = 3.05 eV at room temperature without indication of saturation. A detailed analysis of the hν dependence of α including low-temperature absorption data shows that the absorption process can be well approximated by indirect allowed transitions. It is suggested that the fundamental band gap of In{sub 2}O{sub 3} is of indirect nature. The temperature dependence of the fundamental band gap is measured over a wide range from 9 to 1273 K and can be well fitted by a single-oscillator model. Compared to other semiconductors the reduction of the gap with increasing temperature is exceptionally strong in In{sub 2}O{sub 3}. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Anomalously temperature-dependent thermal conductivity of monolayer GaN with large deviations from the traditional 1 /T law

    Science.gov (United States)

    Qin, Guangzhao; Qin, Zhenzhen; Wang, Huimin; Hu, Ming

    2017-05-01

    Efficient heat dissipation, which is featured by high thermal conductivity, is one of the crucial issues for the reliability and stability of nanodevices. However, due to the generally fast 1 /T decrease of thermal conductivity with temperature increase, the efficiency of heat dissipation quickly drops down at an elevated temperature caused by the increase of work load in electronic devices. To this end, pursuing semiconductor materials that possess large thermal conductivity at high temperature, i.e., slower decrease of thermal conductivity with temperature increase than the traditional κ ˜1 /T relation, is extremely important to the development of disruptive nanoelectronics. Recently, monolayer gallium nitride (GaN) with a planar honeycomb structure emerges as a promising new two-dimensional material with great potential for applications in nano- and optoelectronics. Here, we report that, despite the commonly established 1 /T relation of thermal conductivity in plenty of materials, monolayer GaN exhibits anomalous behavior that the thermal conductivity almost decreases linearly over a wide temperature range above 300 K, deviating largely from the traditional κ ˜1 /T law. The thermal conductivity at high temperature is much larger than the expected thermal conductivity that follows the general κ ˜1 /T trend, which would be beneficial for applications of monolayer GaN in nano- and optoelectronics in terms of efficient heat dissipation. We perform detailed analysis on the mechanisms underlying the anomalously temperature-dependent thermal conductivity of monolayer GaN in the framework of Boltzmann transport theory and further get insight from the view of electronic structure. Beyond that, we also propose two required conditions for materials that would exhibit similar anomalous temperature dependence of thermal conductivity: large difference in atom mass (huge phonon band gap) and electronegativity (LO-TO splitting due to strong polarization of bond). Our

  16. Bare-part color in female budgerigars changes from brown to structural blue following testosterone treatment but is not strongly masculinized.

    Directory of Open Access Journals (Sweden)

    Stefanie E P Lahaye

    Full Text Available Whereas several studies have shown that experimentally increased levels of the androgenic steroid testosterone can affect female behavior, fewer studies have focused on the activational effects of exogenous testosterone on female morphology. With respect to colorful displays in birds, almost exclusively the effects of testosterone manipulation on female carotenoid-based colorations have been studied. Other color types such as structural colors (i.e. UV, blue and violet colors that result from differential light reflection in the nanostructures of the tissue remain largely unstudied. Here, we investigated the short- and long-term effects of exogenous testosterone on the expression of structural bare-part coloration in female budgerigars, Melopsittacus undulatus. In this parrot species, bare-part coloration is expressed in the cere, a structure over the beak which is brown in females and structural blue in males. We experimentally increased plasma testosterone levels in testosterone-treated females (T-females compared to controls (C-females and we performed weekly spectrophotometric measurements of the cere for five weeks after implantation and one measurement after ten weeks. We also estimated the extent to which testosterone masculinized female cere color by comparing the experimental females with untreated males. We found significant effects of testosterone on cere color from week four after implantation onwards. T-females expressed significantly bluer ceres than C-females with higher values for brightness and UV reflectance. T-female cere color, however, remained significantly less blue than in males, while values for brightness and UV reflectance were significantly higher in T-females than in males. Our quantitative results show that exogenous testosterone induces the expression of structural blue color in females but does not strongly masculinize female cere coloration. We provide several potential pathways for the action of testosterone on

  17. Understanding Biological Rates and their Temperature Dependence, from Enzymes to Ecosystems

    Science.gov (United States)

    Prentice, E.; Arcus, V. L.

    2017-12-01

    Temperature responses over various scales in biological systems follow a similar pattern; negative curvature results in an optimum temperature (Topt) for activity/growth/turnover, with decreases in rates on either side of Topt. Previously this downturn in rates at high temperatures has been attributed to enzyme denaturation, where a failing of the basic driving units of metabolism was used to describe curvature at the enzyme and organism level. However, recent developments in our understanding of the factors governing enzyme rates at different temperatures have guided a new understanding of the responses of biological systems. Enzymes catalyse reactions by driving the substrate through a high energy species, which is tightly bound to the enzyme. Macromolecular rate theory (MMRT) has recently been developed to account for the changes in the system brought about by this tight binding, specifically the change in the physical parameter heat capacity (ΔCǂp), and the effect this has on the temperature dependence of enzyme reactions. A negative ΔCǂp imparts the signature negative curvature to rates in the absence of denaturation, and finds that Topt, ΔCǂp and curvature are all correlated, placing constraints on biological systems. The simplest of cells comprise thousands of enzymatically catalysed reactions, functioning in series and in parallel in metabolic pathways to determine the overall growth rate of an organism. Intuitively, the temperature effects of enzymes play a role in determining the overall temperature dependence of an organism, in tandem with cellular level regulatory responses. However, the effect of individual Topt values and curvature on overall pathway behaviour is less apparent. Here, this is investigated in the context of MMRT through the in vitro characterisation of a six-step metabolic pathway to understand the steps in isolation and functioning in series. Pathway behaviour is found to be approximately an average of the properties of the

  18. Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Warkentin, Matthew, E-mail: maw64@cornell.edu; Thorne, Robert E. [Physics Department, Cornell University, Ithaca, New York (United States)

    2010-10-01

    Radiation damage to protein crystals exhibits two regimes of temperature-activated behavior between T = 300 and 100 K, with a crossover at the protein glass transition near 200 K. These results have implications for mechanistic studies of proteins and for structure determination when cooling to T = 100 K creates excessive disorder. The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol{sup −1} indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol{sup −1}, which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300–80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962 ▶), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183–191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for

  19. Generalized Magneto-thermo-microstretch Response of a Half-space with Temperature-dependent Properties During Thermal Shock

    Directory of Open Access Journals (Sweden)

    Qi-lin Xiong

    Full Text Available Abstract The generalized magneto-thermoelastic problem of an infinite homogeneous isotropic microstretch half-space with temperature-dependent material properties placed in a transverse magnetic field is investigated in the context of different generalized thermoelastic theories. The upper surface of the half-space is subjected to a zonal time-dependent heat shock. By solving finite element governing equations, the solution to the problem is obtained, from which the transient magneto-thermoelastic responses, including temperature, stresses, displacements, microstretch, microrotation, induced magnetic field and induced electric field are presented graphically. Comparisons are made in the results obtained under different generalized thermoelastic theories to show some unique features of generalized thermoelasticity, and comparisons are made in the results obtained under three forms of temperature dependent material properties (absolute temperature dependent, reference temperature dependent and temperature-independent to show the effects of absolute temperature and reference temperature. Weibull or Log-normal.

  20. Elevated temperature dependence of the anisotropic visible-to-ultraviolet dielectric function of monoclinic β-Ga2O3

    Science.gov (United States)

    Mock, A.; VanDerslice, J.; Korlacki, R.; Woollam, J. A.; Schubert, M.

    2018-01-01

    We report on the temperature dependence of the dielectric tensor elements of n-type conductive β-Ga2O3 from 22 °C to 550 °C in the spectral range of 1.5 eV-6.4 eV. We present the temperature dependence of the excitonic and band-to-band transition energy parameters using a previously described eigendielectric summation approach [A. Mock et al., Phys. Rev. B 96, 245205 (2017)]. We utilize a Bose-Einstein analysis of the temperature dependence of the observed transition energies and reveal electron coupling with average phonon temperature in excellent agreement with the average over all longitudinal phonon plasmon coupled modes reported previously [M. Schubert et al., Phys. Rev. B 93, 125209 (2016)]. We also report a linear temperature dependence of the wavelength independent Cauchy expansion coefficient for the anisotropic below-band-gap monoclinic dielectric tensor elements.

  1. Temperature-dependent photoluminescence analysis of ZnO nanowire array annealed in air

    Science.gov (United States)

    Sun, Yanan; Gu, Xiuquan; Zhao, Yulong; Wang, Linmeng; Qiang, Yinghuai

    2018-05-01

    ZnO nanowire arrays (NWAs) were prepared on transparent conducting fluorine doped tin oxide (FTO) substrates through a facile hydrothermal method, followed by a 500 °C annealing to improve their crystalline qualities and photoelectrochemical (PEC) activities. It was found that the annealing didn't change the morphology, but resulted in a significant reduction of the donor concentration. Temperature-dependent photoluminescence (PL) was carried out for a comprehensive analysis of the effect from annealing. Noteworthy, four dominant peaks were identified from the 10 K spectrum of a 500 °C annealed sample, and they were assigned to FX, D0X, (e, D0) and (e, D0) -1LO, respectively. Of them, the FX emission was only existed below 130 K, while the room-temperature (RT) PL spectrum was dominated by the D0X emission.

  2. Temperature-dependent sex determination in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Viets, B E; Tousignant, A; Ewert, M A; Nelson, C E; Crews, D

    1993-05-01

    The leopard gecko, Eublepharis macularius, has temperature-dependent sex determination (TSD). Previous reports have shown that females are produced predominantly at cool incubation temperatures and males are produced predominantly at warm incubation temperatures (Pattern Ib). We report here that incubation at even higher temperatures (34 and 35 degrees C) produces mostly females (Pattern II). The lethal maximum constant incubation temperature for this species appears to be just above 35 degrees C. Although a previous study indicated that females from a warm incubation temperature (32 degrees C) failed to lay eggs, we found that 12 of 14 mature females incubated at 32.5 degrees C, and 5 of 6 mature females incubated at 34 degrees C produced fertile eggs and viable hatchlings.

  3. Evaluation of enthalpy of interfacial reactions from temperature dependency of interfacial equilibrium

    International Nuclear Information System (INIS)

    Kallay, Nikola; Cop, Ana

    2005-01-01

    Temperature dependency of equilibrium at metal oxide-aqueous electrolyte solution interface was analyzed by numerical simulation. Derivations of inner surface potential with respect to temperature were performed at constant values of several different parameters. When surface charge density in inner plane was kept constant the reasonable results were obtained, i.e. the electrostatic contribution to enthalpy of protonation of amphotheric surface sites was found to be positive in the pH region below the point of zero potential and negative above this point. All other examined possibilities produced opposite results. Derivation of empirical interfacial equilibrium constant at constant surface potential indicated that electrostatic effect on protonation entropy is negligible and that electrostatic contributions to reaction Gibbs energy and enthalpy are equal and directly related to the surface potential in the inner plane

  4. An Ab Initio Description of the Excitonic Properties of LH2 and Their Temperature Dependence.

    Science.gov (United States)

    Cupellini, Lorenzo; Jurinovich, Sandro; Campetella, Marco; Caprasecca, Stefano; Guido, Ciro A; Kelly, Sharon M; Gardiner, Alastair T; Cogdell, Richard; Mennucci, Benedetta

    2016-11-10

    The spectroscopic properties of light-harvesting (LH) antennae in photosyntehtic organisms represent a fingerprint that is unique for each specific pigment-protein complex. Because of that, spectroscopic observations are generally combined with structural data from X-ray crystallography to obtain an indirect representation of the excitonic properties of the system. Here, an alternative strategy is presented which goes beyond this empirical approach and introduces an ab initio computational description of both structural and electronic properties and their dependence on the temperature. The strategy is applied to the peripheral light-harvesting antenna complex (LH2) present in purple bacteria. By comparing this model with the one based on the crystal structure, a detailed, molecular level explanation of the absorption and circular dichroism (CD) spectra and their temperature dependence is achieved. The agreement obtained with the experiments at both low and room temperature lays the groundwork for an atomistic understanding of the excitation dynamics in the LH2 system.

  5. Temperature dependence of the fundamental excitonic resonance in lead-salt quantum dots

    International Nuclear Information System (INIS)

    Yue, Fangyu; Tomm, Jens W.; Kruschke, Detlef; Ullrich, Bruno; Chu, Junhao

    2015-01-01

    The temperature dependences of the fundamental excitonic resonance in PbS and PbSe quantum dots fabricated by various technologies are experimentally determined. Above ∼150 K, sub-linearities of the temperature shifts and halfwidths are observed. This behavior is analyzed within the existing standard models. Concordant modeling, however, becomes possible only within the frame of a three-level system that takes into account both bright and dark excitonic states as well as phonon-assisted carrier redistribution between these states. Our results show that luminescence characterization of lead-salt quantum dots necessarily requires both low temperatures and excitation densities in order to provide reliable ensemble parameters

  6. Temperature-dependent layer breathing modes in two-dimensional materials

    Science.gov (United States)

    Maity, Indrajit; Maiti, Prabal K.; Jain, Manish

    2018-04-01

    Relative out-of-plane displacements of the constituent layers of two-dimensional materials give rise to unique low-frequency breathing modes. By computing the height-height correlation functions from molecular dynamics simulations, we show that the layer breathing modes (LBMs) can be mapped consistently to vibrations of a simple linear chain model. Our calculated thickness dependence of LBM frequencies for few-layer (FL) graphene and molybdenum disulfide (MoS2) are in excellent agreement with available experiments. Our results show a redshift of LBM frequency with an increase in temperature, which is a direct consequence of anharmonicities present in the interlayer interaction. We also predict the thickness and temperature dependence of LBM frequencies for FL hexagonal boron nitride. Our Rapid Communication provides a simple and efficient way to probe the interlayer interaction for layered materials and their heterostructures with the inclusion of anharmonic effects.

  7. Temperature dependence of relaxation times in proton components of fatty acids

    International Nuclear Information System (INIS)

    Kuroda, Kagayaki; Iwabuchi, Taku; Saito, Kensuke; Obara, Makoto; Honda, Masatoshi; Imai, Yutaka

    2011-01-01

    We examined the temperature dependence of relaxation times in proton components of fatty acids in various samples in vitro at 11 tesla as a standard calibration data for quantitative temperature imaging of fat. The spin-lattice relaxation time, T 1 , of both the methylene (CH 2 ) chain and terminal methyl (CH 3 ) was linearly related to temperature (r>0.98, P 2 signal for calibration and observed the signal with 18% of CH 3 to estimate temperature. These findings suggested that separating the fatty acid components would significantly improve accuracy in quantitative thermometry for fat. Use of the T 1 of CH 2 seems promising in terms of reliability and reproducibility in measuring temperature of fat. (author)

  8. Temperature dependence of radiation colloidal centers production and annealing in alkali halide crystals

    International Nuclear Information System (INIS)

    Kristapson, J.Z.; Ozerskii, V.J.

    1981-01-01

    The investigation results on temperature dependences of production and annealing of radiation colloidal color centers have been reviewed. In order to produce such centers in NaCl, KCl and KBr crystals the doses of 10 2 -10 4 Mrad as well as irradiation temperatures of 300-600 K and post-irradiation heating of up to 800 K were applied. It has been demonstrated that to produce X-centers, it is necessary to have optimal temperature and initial critical dose during both irradiation and post-irradiation heating of crystals. It has been also found that during annealing hole centers produced are different with regard to thermal stability. The possible recombination mechanisms of hole and electron products of radiolysis during post-irradiation heating has been analyzed [ru

  9. Temperature dependence of bulk modulus and second-order elastic constants

    International Nuclear Information System (INIS)

    Singh, P.P.; Kumar, Munish

    2004-01-01

    A simple theoretical model is developed to investigate the temperature dependence of the bulk modulus and second order elastic constants. The method is based on the two different approaches viz. (i) the theory of thermal expansivity formulated by Suzuki, based on the Mie-Gruneisen equation of state, (ii) the theory of high-pressure-high-temperature equation of state formulated by Kumar, based on thermodynamic analysis. The results obtained for a number of crystals viz. NaCl, KCl, MgO and (Mg, Fe) 2 SiO 4 are discussed and compared with the experimental data. It is concluded that the Kumar formulation is far better that the Suzuki theory of thermal expansivity

  10. Molecular-dynamics theory of the temperature-dependent surface phonons of W(001)

    International Nuclear Information System (INIS)

    Wang, C.Z.; Fasolino, A.; Tosatti, E.

    1987-04-01

    We study the temperature-dependent zone-boundary surface phonons across the c(2x2)→1x1 reconstruction phase transition of the clean W(001) surface. Velocity-velocity correlations and hence the phonon spectral densities are calculated by molecular dynamics for the surface atoms of a finite thickness (001) slab, with interatomic potentials established in a previous study of the surface statics. Our calculated k = (1/2,1/2)(2π/a) surface phonon are dominated by three main low-frequency modes. Of these, the longitudinal and the shear horizontal are reconstruction-related and display critical broadening and softening at the phase transition, while the third, the shear vertical, is basically unaffected. The reconstruction phase mode, shear horizontal, appears to be responsible for the phase fluctuations which destroy long-range order at the transition. (author). 30 refs, 12 figs

  11. Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

    International Nuclear Information System (INIS)

    Olsson, Kevin S.; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin

    2015-01-01

    Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons

  12. Temperature dependent lattice constant of InSb above room temperature

    Science.gov (United States)

    Breivik, Magnus; Nilsen, Tron Arne; Fimland, Bjørn-Ove

    2013-10-01

    Using temperature dependent X-ray diffraction on two InSb single crystalline substrates, the bulk lattice constant of InSb was determined between 32 and 325 °C. A polynomial function was fitted to the data: a(T)=6.4791+3.28×10-5×T+1.02×10-8×T2 Å (T in °C), which gives slightly higher values than previously published (which go up to 62 °C). From the fit, the thermal expansion of InSb was calculated to be α(T)=5.062×10-6+3.15×10-9×T K-1 (T in °C). We found that the thermal expansion coefficient is higher than previously published values above 100 °C (more than 10% higher at 325 °C).

  13. Modeling of Temperature-Dependent Noise in Silicon Nanowire FETs including Self-Heating Effects

    Directory of Open Access Journals (Sweden)

    P. Anandan

    2014-01-01

    Full Text Available Silicon nanowires are leading the CMOS era towards the downsizing limit and its nature will be effectively suppress the short channel effects. Accurate modeling of thermal noise in nanowires is crucial for RF applications of nano-CMOS emerging technologies. In this work, a perfect temperature-dependent model for silicon nanowires including the self-heating effects has been derived and its effects on device parameters have been observed. The power spectral density as a function of thermal resistance shows significant improvement as the channel length decreases. The effects of thermal noise including self-heating of the device are explored. Moreover, significant reduction in noise with respect to channel thermal resistance, gate length, and biasing is analyzed.

  14. Solution for laminar natural convection flows in a square cavity with temperature dependent viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, J.G. [Parsons Brinckerhoff, New York, NY (United States)

    1995-12-31

    This paper presents an examination of numerical results for the buoyancy-driven convection heat transfer problem, in a two-dimensional enclosure under steady-state, laminar, incompressible, and temperature dependent viscosity fluid flow conditions. The vertical walls are exposed to different temperatures and the top and bottom are insulated. Rayleigh numbers of 10{sup 4}, 10{sup 5}, and 10{sup 6} are considered. Specific heat, thermal conductivity, and the thermal expansion coefficient are assumed constant. Density variation is included using the Oberbeck-Boussinesq approximation. The results are obtained using the SIMPLEC solution technique based on a power-law, finite-volume discretization scheme. The hydrodynamic and thermal fields are presented at various locations in the enclosures.

  15. Temperature dependence of velocity of sound in high-Tc superconductors in normal state

    International Nuclear Information System (INIS)

    Bishoyi, K.C.; Rout, G.C.; Behera, S.N.

    2002-01-01

    A microscopic theoretical calculation of temperature dependence of velocity of sound in high temperature superconductors is addressed in this paper. The influence of model parameters of the system in its normal phase is investigated through numerical calculations. The results at the room temperature as well as low temperatures (∼ 25 K), are discussed. The dimensionless parameters involved in the calculations are the electron-phonon coupling (g), staggered magnetic field (h), hybridization (V), position of the f-level (d), temperature (t) and the conduction band width (ω). The model Hamiltonian contains the antiferromagnetism in conduction electrons of cooper and the electron-phonon interaction through the hybridization between conduction electrons and f-electrons of impurity atoms. The phonon Green's functions are calculated by Zubarev's technique. The velocity of sound is calculated in the long wavelength and finite temperature limit. (author)

  16. Temperature dependence of luminescence for different surface flaws in high purity silica glass

    International Nuclear Information System (INIS)

    Fournier, J.; Grua, P.; Neauport, J.; Fargin, E.; Jubera, V.; Talaga, D.; Del Guerzo, A.; Raffy, G.; Jouannigot, S.

    2013-01-01

    In situ temperature dependence of the Photoluminescence under 325 nm irradiation is used to investigate defect populations existing in different surface flaws in high purity fused silica. Five photoluminescence bands peaking at 1.9, 2.1, 2.3, 2.63 and 3.11 eV have been detected in the spectral area ranging from 1.6 up to 3.6 eV. The Gaussian deconvolution of spectra allows dividing the five luminescence bands in two categories. The former corresponds to bands showing a significant intensity enhancement while temperature decreases; the latter corresponds to bands remaining insensitive to the temperature evolution. Such a behavior brings new information on defects involved in laser damage mechanism at 351 nm in nanosecond regime. (authors)

  17. Analytical pair correlations in ideal quantum gases: temperature-dependent bunching and antibunching.

    Science.gov (United States)

    Bosse, J; Pathak, K N; Singh, G S

    2011-10-01

    The fluctuation-dissipation theorem together with the exact density response spectrum for ideal quantum gases has been utilized to yield a new expression for the static structure factor, which we use to derive exact analytical expressions for the temperature-dependent pair distribution function g(r) of the ideal gases. The plots of bosonic and fermionic g(r) display "Bose pile" and "Fermi hole" typically akin to bunching and antibunching as observed experimentally for ultracold atomic gases. The behavior of spin-scaled pair correlation for fermions is almost featureless, but bosons show a rich structure including long-range correlations near T(c). The coherent state at T=0 shows no correlation at all, just like single-mode lasers. The depicted decreasing trend in correlation with decrease in temperature for T

  18. Temperature-dependent dielectric properties in ITO/AF/Al device

    International Nuclear Information System (INIS)

    Choi, Hyun-Min; Kim, Won-Jong; Lee, Jong-Yong; Hong, Jin-Woong; Kim, Tae-Wan

    2010-01-01

    Temperature-dependent dielectric properties were studied in a device with a structure of ITO/amorphous fluoropolymer (AF)/Al. The AF was thermally deposited at a deposition rate of 0.1 A/s to a thickness of 20 nm under a pressure of 5 x 10 -6 Torr. From the dielectric properties of the device, an equivalent circuit for and the equivalent complex impedance Z eq of the device were obtained. The interfacial resistance was found to be approximately 38 Ω. As the temperature was increased, the radius of the Cole-Cole plot and β also increased for a constant applied voltage. However, as the applied voltage was increased, those values decreased at a constant temperature. These behaviors are thought to be due to an orientational polarization effect of the molecules inside the AF layer.

  19. Magnetic-field and temperature dependence of the energy gap in InN nanobelt

    Directory of Open Access Journals (Sweden)

    K. Aravind

    2012-03-01

    Full Text Available We present tunneling measurements on an InN nanobelt which shows signatures of superconductivity. Superconducting transition takes place at temperature of 1.3K and the critical magnetic field is measured to be about 5.5kGs. The energy gap extrapolated to absolute temperature is about 110μeV. As the magnetic field is decreased to cross the critical magnetic field, the device shows a huge zero-bias magnetoresistance ratio of about 400%. This is attributed to the suppression of quasiparticle subgap tunneling in the presence of superconductivity. The measured magnetic-field and temperature dependence of the superconducting gap agree well with the reported dependences for conventional metallic superconductors.

  20. Temperature dependence of the cross section for the fragmentation of thymine via dissociative electron attachment

    Energy Technology Data Exchange (ETDEWEB)

    Kopyra, Janina [Faculty of Science, Siedlce University, 3 Maja 54, 08-110 Siedlce (Poland); Abdoul-Carime, Hassan, E-mail: hcarime@ipnl.in2p3.fr [Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 43 Bd du 11 novembre 1918, 69622 Villeurbanne Cedex (France)

    2015-05-07

    Providing experimental values for absolute Dissociative Electron Attachment (DEA) cross sections for nucleobases at realistic biological conditions is a considerable challenge. In this work, we provide the temperature dependence of the cross section, σ, of the dehydrogenated thymine anion (T − H){sup −} produced via DEA. Within the 393-443 K temperature range, it is observed that σ varies by one order of magnitude. By extrapolating to a temperature of 313 K, the relative DEA cross section for the production of the dehydrogenated thymine anion at an incident energy of 1 eV decreases by 2 orders of magnitude and the absolute value reaches approximately 6 × 10{sup −19} cm{sup 2}. These quantitative measurements provide a benchmark for theoretical prediction and also a contribution to a more accurate description of the effects of ionizing radiation on molecular medium.

  1. Temperature dependent recombination dynamics in InP/ZnS colloidal nanocrystals

    Science.gov (United States)

    Shirazi, R.; Kopylov, O.; Kovacs, A.; Kardynał, B. E.

    2012-08-01

    In this letter, we investigate exciton recombination in InP/ZnS core-shell colloidal nanocrystals over a wide temperature range. Over the entire range between room temperature and liquid helium temperature, multi-exponential exciton decay curves are observed and well explained by the presence of bright and dark exciton states, as well as defect states. Two different types of defect are present: one located at the core-shell interface and the other on the surface of the nanocrystal. Based on the temperature dependent contributions of all four states to the total photoluminescence signal, we estimate that the four states are distributed within a 20 meV energy band in nanocrystals that emit at 1.82 eV.

  2. Temperature dependence of the optical absorption spectra of InP/ZnS quantum dots

    Science.gov (United States)

    Savchenko, S. S.; Vokhmintsev, A. S.; Weinstein, I. A.

    2017-03-01

    The optical-absorption spectra of InP/ZnS (core/shell) quantum dots have been studied in a broad temperature range of T = 6.5-296 K. Using the second-order derivative spectrophotometry technique, the energies of optical transitions at room temperature were found to be E 1 = 2.60 ± 0.02 eV (for the first peak of excitonic absorption in the InP core) and E 2 = 4.70 ± 0.02 eV (for processes in the ZnS shell). The experimental curve of E 1( T) has been approximated for the first time in the framework of a linear model and in terms of the Fan's formula. It is established that the temperature dependence of E 1 is determined by the interaction of excitons and longitudinal acoustic phonons with hω = 15 meV.

  3. Transresistance calibrations and temperature dependence evaluation of a magnetic bridge current sensor with shunt standards

    International Nuclear Information System (INIS)

    Yamada, T; Kon, S; Tadatsu, T

    2011-01-01

    This paper deals with a magnetic bridge current sensor for dc current measurements and a calibration system developed for the current sensor. The current sensor forms a magnetic bridge structure with a magnetic fluid core. The calibration system has been developed by using standard shunts for a test current range of 1 mA to 100 A and establishing a comparison method with a switching/sampling system. In the calibration system, the transresistances of the current sensor are measured and the uncertainties of the system are estimated for the input test current range. Also, the temperature dependence on the transresistances is investigated for temperatures ranging from −40 to 100 °C

  4. Temperature-dependent phase transitions in zeptoliter volumes of a complex biological membrane

    International Nuclear Information System (INIS)

    Nikiforov, Maxim P; Jesse, Stephen; Kalinin, Sergei V; Hohlbauch, Sophia; Proksch, Roger; King, William P; Voitchovsky, Kislon; Contera, Sonia Antoranz

    2011-01-01

    Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50-60 deg. C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 ± 5 deg. C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.

  5. Temperature-dependent thermo-elastic properties of s-, p- and d-block liquid metals

    International Nuclear Information System (INIS)

    Singh, R.N.; Arafin, S.; George, A.K.

    2007-01-01

    Thermodynamic relations involving experimentally known physical quantities are used to determine the ratio of specific heats, γ, for s-block (Na, K, Rb, Cs, Mg), d-block (Fe, Co, Ni, Cu, Ag, Au, Zn, Cd, Hg,) and p-block (Al, Ga, In, Tl, Sn, Pb, Sb, Bi, Se, Te) liquid metals. γ is further utilized to determine reliable values for the isothermal compressibility (κ T ) and the specific heat at constant volume (C V ) for these liquid metals near and above the melting temperatures. These data are of considerable significance for various thermo-physical analysis of liquid metals. We have also evaluated the Grueneisen function and its temperature dependence to establish the correlation between the thermal expansion and the elastic response to thermally induced stress. The values of acoustic impedance for liquid metals are evaluated and its physical significance is discussed for the transmission of elastic waves across metallic interfaces

  6. Temperature-dependent magnetic properties of individual glass spherules, Apollo 11, 12, and 14 lunar samples.

    Science.gov (United States)

    Thorpe, A. N.; Sullivan, S.; Alexander, C. C.; Senftle, F. E.; Dwornik, E. J.

    1972-01-01

    Magnetic susceptibility of 11 glass spherules from the Apollo 14 lunar fines have been measured from room temperature to 4 K. Data taken at room temperature, 77 K, and 4.2 K, show that the soft saturation magnetization was temperature independent. In the temperature range 300 to 77 K the temperature-dependent component of the magnetic susceptibility obeys the Curie law. Susceptibility measurements on these same specimens and in addition 14 similar spherules from the Apollo 11 and 12 mission show a Curie-Weiss relation at temperatures less than 77 K with a Weiss temperature of 3-7 degrees in contrast to 2-3 degrees found for tektites and synthetic glasses of tektite composition. A proposed model and a theoretical expression closely predict the variation of the susceptibility of the glass spherules with temperature.

  7. Unusual temperature dependence of the magnetic moment in URu2Si2

    International Nuclear Information System (INIS)

    Faak, B.; Flouquet, J.; Lejay, P.

    1994-01-01

    The influence of the sample quality on the magnetic properties of the heavy-fermion superconductor URu 2 Si 2 has been studied by elastic neutron scattering. Two single crystals prepared under identical conditions received different heat treatments. The as-grown crystal shows an unusual temperature dependence of the magnetic Bragg peak intensity. The annealed sample behaves normally. The low-temperature magnetic moment is identical for the two samples, showing that the small moment of 0.023 (3) μ B is intrinsic. By varying the instrumental resolution, we show that the ordered moment as well as the limited correlation length (200-400 A) are of static origin. The finite correlation length appears related to defects. (author). 9 refs., 1 fig

  8. Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

    2011-01-01

    Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures...... such as heat production from coal oxidation may be equally important....... as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78°N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both...

  9. A temperature-dependent coarse-grained model for the thermoresponsive polymer poly(N-isopropylacrylamide)

    International Nuclear Information System (INIS)

    Abbott, Lauren J.; Stevens, Mark J.

    2015-01-01

    In this study, a coarse-grained (CG) model is developed for the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM), using a hybrid top-down and bottom-up approach. Nonbonded parameters are fit to experimental thermodynamic data following the procedures of the SDK (Shinoda, DeVane, and Klein) CG force field, with minor adjustments to provide better agreement with radial distribution functions from atomistic simulations. Bonded parameters are fit to probability distributions from atomistic simulations using multi-centered Gaussian-based potentials. The temperature-dependent potentials derived for the PNIPAM CG model in this work properly capture the coil-globule transition of PNIPAM single chains and yield a chain-length dependence consistent with atomistic simulations

  10. Temperature dependence of the infrared luminescence of ZnSe grown

    International Nuclear Information System (INIS)

    Vakulenko, O.V.; Kravchenko, V.M.

    2000-01-01

    Photoluminescence (PL) spectra of undoped ZnSe crystals grown by the sublimation method are studied within the spectral range 500-1030 nm at T 100/330 K. PL was excited with N 2 , He - Cd, and Ar + lasers. Under Ar + laser excitation (h ν e xc g ), the IP 1.3 eV band is observed in addition to the red 1.9 eV band. The temperature dependences of the peak intensities (TD) of both bands are measured. The TD of IR band has a peak at 260 K and flattens out at T < 180. To interpret such a TD, two models are considered the model of multi charge donor as a luminescence center and the model of simple donor. It is suggested that the IR PL band may be due to intracentor transitions between some levels of multi charge donor-like defects of the ZnSe lattice

  11. Anomalous temperature dependent magneto-conductance in organic light-emitting diodes with multiple emissive states

    Science.gov (United States)

    Zhao, Chen-xiao; Jia, Wei-yao; Huang, Ke-Xun; Zhang, Qiao-ming; Yang, Xiao-hui; Xiong, Zu-hong

    2015-07-01

    The temperature dependence of the magneto-conductance (MC) in organic electron donor-acceptor hybrid and layer heterojunction diodes was studied. The MC value increased with temperature in layer heterojunction and in 10 wt. % hybrid devices. An anomalous decrease of the MC with temperature was observed in 25 wt. %-50 wt. % hybrid devices. Further increasing donor concentration to 75 wt. %, the MC again increased with temperature. The endothermic exciplex-exciton energy transfer and the change in electroplex/exciton ratio caused by change in charge transport with temperature may account for these phenomena. Comparative studies of the temperature evolutions of the IV curves and the electroluminescence and photoluminescence spectra back our hypothesis.

  12. Anomalous temperature dependent magneto-conductance in organic light-emitting diodes with multiple emissive states

    International Nuclear Information System (INIS)

    Zhao, Chen-xiao; Jia, Wei-yao; Huang, Ke-Xun; Zhang, Qiao-ming; Yang, Xiao-hui; Xiong, Zu-hong

    2015-01-01

    The temperature dependence of the magneto-conductance (MC) in organic electron donor-acceptor hybrid and layer heterojunction diodes was studied. The MC value increased with temperature in layer heterojunction and in 10 wt. % hybrid devices. An anomalous decrease of the MC with temperature was observed in 25 wt. %–50 wt. % hybrid devices. Further increasing donor concentration to 75 wt. %, the MC again increased with temperature. The endothermic exciplex-exciton energy transfer and the change in electroplex/exciton ratio caused by change in charge transport with temperature may account for these phenomena. Comparative studies of the temperature evolutions of the IV curves and the electroluminescence and photoluminescence spectra back our hypothesis

  13. Anomalous temperature dependent magneto-conductance in organic light-emitting diodes with multiple emissive states

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chen-xiao; Jia, Wei-yao; Huang, Ke-Xun; Zhang, Qiao-ming; Yang, Xiao-hui; Xiong, Zu-hong, E-mail: zhxiong@swu.edu.cn [School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715 (China)

    2015-07-13

    The temperature dependence of the magneto-conductance (MC) in organic electron donor-acceptor hybrid and layer heterojunction diodes was studied. The MC value increased with temperature in layer heterojunction and in 10 wt. % hybrid devices. An anomalous decrease of the MC with temperature was observed in 25 wt. %–50 wt. % hybrid devices. Further increasing donor concentration to 75 wt. %, the MC again increased with temperature. The endothermic exciplex-exciton energy transfer and the change in electroplex/exciton ratio caused by change in charge transport with temperature may account for these phenomena. Comparative studies of the temperature evolutions of the IV curves and the electroluminescence and photoluminescence spectra back our hypothesis.

  14. Temperature-dependent toxicity of artemisinin toward the macrophyte Lemna minor and the algae Pseudokirchneriella subcapitata

    DEFF Research Database (Denmark)

    Jessing, Karina Knudsmark; Andresen, Marianne; Cedergreen, Nina

    2014-01-01

    - and groundwater. To make better risk assessments of A. annua which is cultivated under varying climatic conditions, the temperature-dependent toxicity of artemisinin toward the green algae Pseudokirchneriella subcapitata and the macrophyte Lemna minor was evaluated at temperatures ranging from 10 to 30°C....... To include a possible effect of temperature on the degradation rate of artemisinin, artemisinin concentrations were measured during the experiment and toxicity was related to the time-weighted averages of exposure concentrations. The toxicity of artemisinin toward the macrophyte L. minor and the algae P....... subcapitata increased with increasing growth rates, and we conclude that bioavailability plays a minor role in the observed relation between temperature and toxicity of artemisinin. The obtained results are important for possible future risk assessment of A. annua cultivation....

  15. Temperature dependence of the spin Seebeck effect in [Fe3O4/Pt]n multilayers

    Directory of Open Access Journals (Sweden)

    R. Ramos

    2017-05-01

    Full Text Available We report temperature dependent measurements of the spin Seebeck effect (SSE in multilayers formed by repeated growth of a Fe3O4/Pt bilayer junction. The magnitude of the observed enhancement of the SSE, relative to the SSE in the single bilayer, shows a monotonic increase with decreasing the temperature. This result can be understood by an increase of the characteristic length for spin current transport in the system, in qualitative agreement with the recently observed increase in the magnon diffusion length in Fe3O4 at lower temperatures. Our result suggests that the thermoelectric performance of the SSE in multilayer structures can be further improved by careful choice of materials with suitable spin transport properties.

  16. Temperature dependence of the thermal expansion of neutron-irradiated pyrolytic carbon and graphite

    International Nuclear Information System (INIS)

    Matsuo, Hideto

    1988-01-01

    The effects of neutron irradiation and annealing on the temperature dependence of the linear thermal expansion of pyrolytic carbon and graphite were investigated after irradiation at 930-1280 0 C to a maximum neutron fluence of 2.84 x 10 25 m -2 (E > 29 fJ). After irradiation, little change in the thermal expansion of pyrolytic graphite was observed. However, as-deposited pyrolytic carbon showed an increase in thermal expansion in the perpendicular direction, a decrease in the direction parallel to the deposition plane, and also an increase in the anisotropy of the thermal expansion. Annealing at 2000 0 C did not cause any effective changes for irradiated specimens of either as-deposited pyrolytic carbon or pyrolytic graphite. (author)

  17. Temperature dependency of tensile properties of GFRP composite for wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Yong Hak; Kim, Jong Il; Kim, Dong Jin; Lee, Gun Chang [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2012-09-15

    In this study, the temperature dependency of the tensile properties of a glass fiber reinforced plastic (GFRP) used in wind turbine blades was examined. The tensile strength, elastic modulus, and Poisson's ratio of the tensile specimen manufactured from uniaxial (0 .deg.) and triaxial (0/{+-}45.deg) laminate composite plates were measured at four different testing temperatures-room temperature, -30 .deg. C, -50 .deg. C, and 60 .deg. C. It was found that the tensile strengths and elastic moduli of the uniaxial laminates were greater than those of the triaxial laminates over the testing temperature range. The tensile strength of the two laminates was significantly dependent on the testing temperature, while the dependency of the elastic modulus on the temperature was insignificant. Furthermore, it could be considered that the Poisson's ratio changed slightly with a change in the testing temperature.

  18. Temperature dependency of tensile properties of GFRP composite for wind turbine blades

    International Nuclear Information System (INIS)

    Huh, Yong Hak; Kim, Jong Il; Kim, Dong Jin; Lee, Gun Chang

    2012-01-01

    In this study, the temperature dependency of the tensile properties of a glass fiber reinforced plastic (GFRP) used in wind turbine blades was examined. The tensile strength, elastic modulus, and Poisson's ratio of the tensile specimen manufactured from uniaxial (0 .deg.) and triaxial (0/±45.deg) laminate composite plates were measured at four different testing temperatures-room temperature, -30 .deg. C, -50 .deg. C, and 60 .deg. C. It was found that the tensile strengths and elastic moduli of the uniaxial laminates were greater than those of the triaxial laminates over the testing temperature range. The tensile strength of the two laminates was significantly dependent on the testing temperature, while the dependency of the elastic modulus on the temperature was insignificant. Furthermore, it could be considered that the Poisson's ratio changed slightly with a change in the testing temperature

  19. Temperature-dependent mechanical properties of single-layer molybdenum disulphide: Molecular dynamics nanoindentation simulations

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Junhua, E-mail: junhua.zhao@uni-weimar.de [Jiangsu Province Key Laboratory of Advanced Manufacturing Equipment and Technology of Food, Jiangnan University, 214122 Wuxi (China); Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); Jiang, Jin-Wu, E-mail: jwjiang5918@hotmail.com [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); Rabczuk, Timon, E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, 136-701 Seoul (Korea, Republic of)

    2013-12-02

    The temperature-dependent mechanical properties of single-layer molybdenum disulphide (MoS{sub 2}) are obtained using molecular dynamics (MD) nanoindentation simulations. The Young's moduli, maximum load stress, and maximum loading strain decrease with increasing temperature from 4.2 K to 500 K. The obtained Young's moduli are in good agreement with those using our MD uniaxial tension simulations and the available experimental results. The tendency of maximum loading strain with different temperature is opposite with that of metal materials due to the short range Stillinger-Weber potentials in MoS{sub 2}. Furthermore, the indenter tip radius and fitting strain effect on the mechanical properties are also discussed.

  20. Temperature dependence of the chromium(III) R1 linewidth in emerald

    Science.gov (United States)

    Carceller-Pastor, Ivana; Hutchison, Wayne D.; Riesen, Hans

    2013-03-01

    The temperature dependent contribution to the R1 (2E ← 4A2) linewidth in emerald, Be3Al2Si6O18:Cr3, has been measured by employing spectral hole-burning, fluorescence line narrowing and conventional luminescence experiments. The contribution varies from 0.6 MHz at 6.5 K to ˜420 GHz at 240 K and the line red-shifts by ˜570 GHz. Above 60 K, the dependence is well described by a non-perturbative formalism for two-phonon Raman scattering. Below this temperature the direct one-phonon process between the levels of the split 2E excited state dominates. However, it appears that a localized low-energy phonon leads to a deviation from the standard pattern at lowest temperatures.

  1. Finite-element modelling of superconductors in over-critical regime with temperature dependent resistivity

    International Nuclear Information System (INIS)

    Duron, J; Grilli, F; Antognazza, L; Decroux, M; Stavrev, S; Dutoit, B; Fischer, Oe

    2006-01-01

    In this paper, we present a new numerical model, in which both the thermal and the electromagnetic aspects of the over-critical current regime of HTS materials are taken into account. The electromagnetic and thermal equations have been implemented in finite-element method (FEM) software in order to obtain a novel, closer to reality model for investigating the behaviour of the superconductor when the current exceeds I c . This model has been applied for studying the behaviour of strip lines of an YBCO/Au FCL with a sapphire substrate. Simulations with currents largely exceeding I c have been performed, showing that the total current limitation occurs only when the temperature dependence of the electrical parameters is taken into consideration. Such modelling can replace experiments with currents far exceeding I c which may damage or destroy the studied sample or HTS device

  2. A temperature-dependent coarse-grained model for the thermoresponsive polymer poly(N-isopropylacrylamide)

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, Lauren J.; Stevens, Mark J., E-mail: msteve@sandia.gov [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2015-12-28

    A coarse-grained (CG) model is developed for the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM), using a hybrid top-down and bottom-up approach. Nonbonded parameters are fit to experimental thermodynamic data following the procedures of the SDK (Shinoda, DeVane, and Klein) CG force field, with minor adjustments to provide better agreement with radial distribution functions from atomistic simulations. Bonded parameters are fit to probability distributions from atomistic simulations using multi-centered Gaussian-based potentials. The temperature-dependent potentials derived for the PNIPAM CG model in this work properly capture the coil–globule transition of PNIPAM single chains and yield a chain-length dependence consistent with atomistic simulations.

  3. Quantitative Temperature Dependence of Longitudinal Spin Seebeck Effect at High Temperatures

    Directory of Open Access Journals (Sweden)

    Ken-ichi Uchida

    2014-11-01

    Full Text Available We report temperature-dependent measurements of longitudinal spin Seebeck effects (LSSEs in Pt/Y_{3}Fe_{5}O_{12} (YIG/Pt systems in a high temperature range from room temperature to above the Curie temperature of YIG. The experimental results show that the magnitude of the LSSE voltage in the Pt/YIG/Pt systems rapidly decreases with increasing the temperature and disappears above the Curie temperature. The critical exponent of the LSSE voltage in the Pt/YIG/Pt systems at the Curie temperature is estimated to be 3, which is much greater than that for the magnetization curve of YIG. This difference highlights the fact that the mechanism of the LSSE cannot be explained in terms of simple static magnetic properties in YIG.

  4. Investigation of second grade fluid through temperature dependent thermal conductivity and non-Fourier heat flux

    Science.gov (United States)

    Hayat, T.; Ahmad, Salman; Khan, M. Ijaz; Alsaedi, A.; Waqas, M.

    2018-06-01

    Here we investigated stagnation point flow of second grade fluid over a stretchable cylinder. Heat transfer is characterized by non-Fourier law of heat flux and thermal stratification. Temperature dependent thermal conductivity and activation energy are also accounted. Transformations procedure is applying to transform the governing PDE's into ODE's. Obtained system of ODE's are solved analytically by HAM. Influence of flow variables on velocity, temperature, concentration, skin friction and Sherwood number are analyzed. Obtained outcome shows that velocity enhanced through curvature parameter, viscoelastic parameter and velocities ratio variable. Temperature decays for larger Prandtl number, thermal stratification, thermal relaxation and curvature parameter. Sherwood number and concentration field show opposite behavior for higher estimation of activation energy, reaction rate, curvature parameter and Schmidt number.

  5. Implementation of a method for calculating temperature-dependent resistivities in the KKR formalism

    Science.gov (United States)

    Mahr, Carsten E.; Czerner, Michael; Heiliger, Christian

    2017-10-01

    We present a method to calculate the electron-phonon induced resistivity of metals in scattering-time approximation based on the nonequilibrium Green's function formalism. The general theory as well as its implementation in a density-functional theory based Korringa-Kohn-Rostoker code are described and subsequently verified by studying copper as a test system. We model the thermal expansion by fitting a Debye-Grüneisen curve to experimental data. Both the electronic and vibrational structures are discussed for different temperatures, and employing a Wannier interpolation of these quantities we evaluate the scattering time by integrating the electron linewidth on a triangulation of the Fermi surface. Based thereupon, the temperature-dependent resistivity is calculated and found to be in good agreement with experiment. We show that the effect of thermal expansion has to be considered in the whole calculation regime. Further, for low temperatures, an accurate sampling of the Fermi surface becomes important.

  6. The temperature dependence of the static structure factor for liquid 4He below Tsub(lambda)

    International Nuclear Information System (INIS)

    Puoskari, M.; Kallio, A.; Pollari, P.

    1984-01-01

    The temperature dependence of the structure factor S(k,T) is studied based on an assumption that the anomalous behaviour of S(k,T) below Tsub(lambda) is due to thermally excited rotons and phonons. The calculation of S(k,T) is performed with the help of the HNC-equation from a model density matrix of Penrose which in turn is obtained from a quasiparticle Hamiltonian describing elementary excitations of liquid helium (both phonons and rotons). The results are in qualitative agreement with recent neutron and X-ray scattering experiments below Tsub(lambda). The theoretical temperature correction is used to deduce S(k,T=0) separately from the most recent X-ray and neutron scattering experiments. (Auth.)

  7. Temperature dependence of electron mobility, electroluminescence and photoluminescence of Alq{sub 3} in OLED

    Energy Technology Data Exchange (ETDEWEB)

    Mu Haichuan; White, Dan; Sharpton, Buck [Office of Electronic Miniaturization, University of Alaska at Fairbanks, AK 99701 (United States); Klotzkin, David [Department of Electrical and Computer Engineering and Computer Sciences, University of Cincinnati, Cincinnati, OH 45221 (United States); De Silva, Ajith; Wagner, Hans Peter [Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States)], E-mail: fnhm@uaf.edu

    2008-12-07

    The correlation of electroluminescence (EL), photoluminescence (PL) and electron mobility were investigated over temperature from 60 to 300 K in small-molecule organic light emitting diode (OLED) structures. The devices consisted of ITO/PEDOT(50 nm)/TPD(50 nm)/Alq{sub 3}(60 nm)/LiF(1 nm)/Al(90 nm), and were fabricated with high-vacuum sublimation/evaporation in a cross-linked configuration. Electron mobility was measured using an ac analysis of the device optical modulation characteristics, while PL and EL were measured by measuring optical power out at fixed pump power of 1 mW, and analysis of dc brightness-voltage (L-V) characteristics, respectively. PL intensity and mobility had a clear maximum at around 220 K, while EL efficiency was constant below 220 K and decrease monotonically above. The reason for the temperature dependent EL, PL and electron mobility behaviour will be discussed.

  8. Analysis of equations of state and temperature dependence of thermal expansivity and bulk modulus for silicon

    International Nuclear Information System (INIS)

    Pandya, Tushar C; Bhatt, Apoorva D; Thakar, Nilesh A

    2012-01-01

    In the present paper an attempt has been made for the comparative study of different equations of state for silicon (Phase-1, cubic diamond structure) in the pressure range of 0-11 GPa. We compare the results of different equations of state (EOS) with available experimental data. The Kwon and Kim EOS is found to give far better agreement with the available experimental data. Results obtained by Poirier-Tarantola, Vinet, Tait and Suzuki's equations of state are not giving satisfactory agreement with the available experimental data. In the present study simple methods based on thermodynamic functions are presented to investigate the temperature dependence of thermal expansivity and bulk modulus for silicon. The results are reported for silicon. The calculated values of thermal expansivity are in good agreement with experimental data.

  9. Measurement of the temperature-dependent threshold shear-stress of red blood cell aggregation.

    Science.gov (United States)

    Lim, Hyun-Jung; Nam, Jeong-Hun; Lee, Yong-Jin; Shin, Sehyun

    2009-09-01

    Red blood cell (RBC) aggregation is becoming an important hemorheological parameter, which typically exhibits temperature dependence. Quite recently, a critical shear-stress was proposed as a new dimensional index to represent the aggregative and disaggregative behaviors of RBCs. The present study investigated the effect of the temperature on the critical shear-stress that is required to keep RBC aggregates dispersed. The critical shear-stress was measured at various temperatures (4, 10, 20, 30, and 37 degrees C) through the use of a transient microfluidic aggregometry. The critical shear-stress significantly increased as the blood temperature lowered, which accorded with the increase in the low-shear blood viscosity with the lowering of the temperature. Furthermore, the critical shear-stress also showed good agreement with the threshold shear-stress, as measured in a rotational Couette flow. These findings assist in rheologically validating the critical shear-stress, as defined in the microfluidic aggregometry.

  10. Temperature dependence of the radiation induced change of depletion voltage in silicon PIN detectors

    International Nuclear Information System (INIS)

    Ziock, H.J.; Holzscheiter, K.; Morgan, A.; Palounek, A.P.T.; Ellison, J.; Heinson, A.P.; Mason, M.; Wimpenny, S.J.; Barberis, E.; Cartiglia, N.; Grillo, A.; O'Shaughnessy, K.; Rahn, J.; Rinaldi, P.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E.; Webster, A.; Wichmann, R.; Wilder, M.; Coupal, D.; Pal, T.

    1993-01-01

    The silicon microstrip detectors that will be used in the SDC experiment at the Superconducting Super Collider (SSC) will be exposed to very large fluences of charged particles, neutrons, and gammas. The authors present a study of how temperature affects the change in the depletion voltage of silicon PIN detectors damaged by radiation. They study the initial radiation damage and the short-term and long-term annealing of that damage as a function of temperature in the range from -10 degrees C to +50 degrees C, and as a function of 800 MeV proton fluence up to 1.5 x 10 14 p/cm 2 . They express the pronounced temperature dependencies in a simple model in terms of two annealing time constants which depend exponentially on the temperature

  11. Plateau on temperature dependence of magnetization of nanostructured rare earth titanates

    Science.gov (United States)

    Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Demokritov, S. O.; Perov, D. V.

    2018-05-01

    Magnetic properties of nanocomposite materials containing particles of rare earth titanates of R2Ti2O7 type, where R is a rare earth ion, including "spin ice" materials are investigated. The descending branches of hysteresis loop have been studied in detail in temperature range from 2 to 50 K. It has been shown that nanocomposites with Yb2Ti2O7, Dy2Ti2O7 and Er2Ti2O7 particles have one intersection point of the descending branches in some temperature range unlike many other nanocomposites. It is shown that magnetization has only weak temperature dependence near this point. It has been obtained that nanocomposites with Pr2Ti2O7 and Nd2Ti2O7 particles have no hysteresis loop. All above findings point out to unusual magnetic structures of the studied samples.

  12. A fully automated temperature-dependent resistance measurement setup using van der Pauw method

    Science.gov (United States)

    Pandey, Shivendra Kumar; Manivannan, Anbarasu

    2018-03-01

    The van der Pauw (VDP) method is widely used to identify the resistance of planar homogeneous samples with four contacts placed on its periphery. We have developed a fully automated thin film resistance measurement setup using the VDP method with the capability of precisely measuring a wide range of thin film resistances from few mΩ up to 10 GΩ under controlled temperatures from room-temperature up to 600 °C. The setup utilizes a robust, custom-designed switching network board (SNB) for measuring current-voltage characteristics automatically at four different source-measure configurations based on the VDP method. Moreover, SNB is connected with low noise shielded coaxial cables that reduce the effect of leakage current as well as the capacitance in the circuit thereby enhancing the accuracy of measurement. In order to enable precise and accurate resistance measurement of the sample, wide range of sourcing currents/voltages are pre-determined with the capability of auto-tuning for ˜12 orders of variation in the resistances. Furthermore, the setup has been calibrated with standard samples and also employed to investigate temperature dependent resistance (few Ω-10 GΩ) measurements for various chalcogenide based phase change thin films (Ge2Sb2Te5, Ag5In5Sb60Te30, and In3SbTe2). This setup would be highly helpful for measurement of temperature-dependent resistance of wide range of materials, i.e., metals, semiconductors, and insulators illuminating information about structural change upon temperature as reflected by change in resistances, which are useful for numerous applications.

  13. Temperature Dependence of the Oxygen Reduction Mechanism in Nonaqueous Li–O 2 Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin [Energy; Xu, Wu [Energy; Zheng, Jianming [Energy; Yan, Pengfei [Environmental; Walter, Eric D. [Environmental; Isern, Nancy [Environmental; Bowden, Mark E. [Environmental; Engelhard, Mark H. [Environmental; Kim, Sun Tai [Energy; Department; Read, Jeffrey [Power; Adams, Brian D. [Energy; Li, Xiaolin [Energy; Cho, Jaephil [Department; Wang, Chongmin [Environmental; Zhang, Ji-Guang [Energy

    2017-10-11

    The temperature dependence of the oxygen reduction mechanism in Li-O2 batteries was investigated using carbon nanotube-based air electrodes and 1,2-dimethoxyethane-based electrolyte within a temperature range of 20C to 40C. It is found that the discharge capacity of the Li-O2 batteries decreases from 7,492 mAh g-1 at 40C to 2,930 mAh g-1 at 0C. However, a sharp increase in capacity was found when the temperature was further decreased and a very high capacity of 17,716 mAh g-1 was observed at 20C at a current density of 0.1 mA cm-2. When the temperature increases from 20C to 40C, the morphologies of the Li2O2 formed varied from ultra-small spherical particles to small flakes and then to large flake-stacked toroids. The lifetime of superoxide and the solution pathway play a dominate role on the battery capacity in the temperature range of -20C to 0C, but the electrochemical kinetics of oxygen reduction and the surface pathway dominate the discharge behavior in the temperature range of 0C to 40C. These findings provide fundamental understanding on the temperature dependence of oxygen reduction process in a Li-O2 battery and will enable a more rational design of Li-O2 batteries.

  14. Temperature dependence of plankton community metabolism in the subtropical and tropical oceans

    KAUST Repository

    Garcia-Corral, Lara S.; Holding, Johnna M.; Carrillo-de-Albornoz, Paloma; Steckbauer, Alexandra; Pé rez-Lorenzo, Marí a; Navarro, Nuria; Serret, Pablo; Gasol, Josep M.; Moran, Xose Anxelu G.; Estrada, Marta; Fraile-Nuez, Eugenio; Bení tez-Barrios, Veró nica; Agusti, Susana; Duarte, Carlos M.

    2017-01-01

    Here we assess the temperature dependence of the metabolic rates (gross primary production (GPP), community respiration (CR), and the ratio GPP/CR) of oceanic plankton communities. We compile data from 133 stations of the Malaspina 2010 Expedition, distributed among the subtropical and tropical Atlantic, Pacific, and Indian oceans. We used the in vitro technique to measured metabolic rates during 24 h incubations at three different sampled depths: surface, 20%, and 1% of the photosynthetically active radiation measured at surface. We also measured the % of ultraviolet B radiation (UVB) penetrating at surface waters. GPP and CR rates increased with warming, albeit different responses were observed for each sampled depth. The overall GPP/CR ratio declined with warming. Higher activation energies (E-a) were derived for both processes (GPP(Chla) = 0.97; CRChla = 1.26; CRHPA = 0.95 eV) compared to those previously reported. The Indian Ocean showed the highest E-a (GPP(Chla) = 1.70; CRChla = 1.48; CRHPA = 0.57 eV), while the Atlantic Ocean showed the lowest (GPP(Chla) = 0.86; CRChla = 0.77; CRHPA = -0.13 eV). We believe that the difference between previous assessments and the ones presented here can be explained by the overrepresentation of Atlantic communities in the previous data sets. We found that UVB radiation also affects the temperature dependence of surface GPP, which decreased rather than increased under high levels of UVB. Ocean warming, which causes stratification and oligotrophication of the subtropical and tropical oceans, may lead to reduced surface GPP as a result of increased penetration of UVB radiation.

  15. Time, stress, and temperature-dependent deformation in nanostructured copper: Stress relaxation tests and simulations

    International Nuclear Information System (INIS)

    Yang, Xu-Sheng; Wang, Yun-Jiang; Wang, Guo-Yong; Zhai, Hui-Ru; Dai, L.H.; Zhang, Tong-Yi

    2016-01-01

    In the present work, stress relaxation tests, high-resolution transmission electron microscopy (HRTEM), and molecular dynamics (MD) simulations were conducted on coarse-grained (cg), nanograined (ng), and nanotwinned (nt) copper at temperatures of 22 °C (RT), 30 °C, 40 °C, 50 °C, and 75 °C. The comprehensive investigations provide sufficient information for the building-up of a formula to describe the time, stress, and temperature-dependent deformation and clarify the relationship among the strain rate sensitivity parameter, stress exponent, and activation volume. The typically experimental curves of logarithmic plastic strain rate versus stress exhibited a three staged relaxation process from a linear high stress relaxation region to a subsequent nonlinear stress relaxation region and finally to a linear low stress relaxation region, which only showed-up at the test temperatures higher than 22 °C, 22 °C, and 30 °C, respectively, in the tested cg-, ng-, and nt-Cu specimens. The values of stress exponent, stress-independent activation energy, and activation volume were determined from the experimental data in the two linear regions. The determined activation parameters, HRTEM images, and MD simulations consistently suggest that dislocation-mediated plastic deformation is predominant in all tested cg-, ng-, and nt-Cu specimens in the initial linear high stress relaxation region at the five relaxation temperatures, whereas in the linear low stress relaxation region, the grain boundary (GB) diffusion-associated deformation is dominant in the ng- and cg-Cu specimens, while twin boundary (TB) migration, i.e., twinning and detwinning with parallel partial dislocations, governs the time, stress, and temperature-dependent deformation in the nt-Cu specimens.

  16. Temperature dependence of plankton community metabolism in the subtropical and tropical oceans

    KAUST Repository

    Garcia-Corral, Lara S.

    2017-06-22

    Here we assess the temperature dependence of the metabolic rates (gross primary production (GPP), community respiration (CR), and the ratio GPP/CR) of oceanic plankton communities. We compile data from 133 stations of the Malaspina 2010 Expedition, distributed among the subtropical and tropical Atlantic, Pacific, and Indian oceans. We used the in vitro technique to measured metabolic rates during 24 h incubations at three different sampled depths: surface, 20%, and 1% of the photosynthetically active radiation measured at surface. We also measured the % of ultraviolet B radiation (UVB) penetrating at surface waters. GPP and CR rates increased with warming, albeit different responses were observed for each sampled depth. The overall GPP/CR ratio declined with warming. Higher activation energies (E-a) were derived for both processes (GPP(Chla) = 0.97; CRChla = 1.26; CRHPA = 0.95 eV) compared to those previously reported. The Indian Ocean showed the highest E-a (GPP(Chla) = 1.70; CRChla = 1.48; CRHPA = 0.57 eV), while the Atlantic Ocean showed the lowest (GPP(Chla) = 0.86; CRChla = 0.77; CRHPA = -0.13 eV). We believe that the difference between previous assessments and the ones presented here can be explained by the overrepresentation of Atlantic communities in the previous data sets. We found that UVB radiation also affects the temperature dependence of surface GPP, which decreased rather than increased under high levels of UVB. Ocean warming, which causes stratification and oligotrophication of the subtropical and tropical oceans, may lead to reduced surface GPP as a result of increased penetration of UVB radiation.

  17. Temperature dependence and GABA modulation of [3H]triazolam binding in the rat brain

    International Nuclear Information System (INIS)

    Earle, M.E.; Concas, A.; Wamsley, J.K.; Yamamura, H.I.

    1987-01-01

    The hypnotic triazolam (TZ), a triazolobenzodiazepine displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. The authors major objectives were the direct measurement of the temperature dependence and the gamma-aminobutyric acid (GABA) effect of [ 3 H]TZ binding in the rat brain. Saturation studies showed a shift to lower affinity with increasing temperatures (K/sub d/ = 0.27 +/- 08 nM at 0 0 C; K/sub d/ = 1.96 +/- 0.85 nM at 37 0 C) while the B/sub max/ values remained unchanged (1220 +/- 176 fmoles/mg protein at 0 0 C and 1160 +/- 383 fmoles/mg protein at 37 0 C). Saturation studies of [ 3 H]TZ binding in the presence or absence of GABA (100μM) showed a GABA-shift. At 0 0 C the K/sub d/ values were (K/sub d/ = 0.24 +/- 0.03 nM/-GABA; K/sub d/ = 0.16 +/- 0.04/+GABA) and at 37 0 C the K/sub d/ values were (K/sub d/ = 1.84 +/- 0.44 nM/-GABA; K/sub d/ = 0.95 +/- 0.29 nM/+GABA). In contrast to reported literature, the authors findings show that TZ interacts with benzodiazepine receptors with a temperature dependence and GABA-shift consistent with predicted behavior for benzodiazepine agonists. 20 references, 3 tables

  18. POINT 2011: ENDF/B-VII.1 Beta2 Temperature Dependent Cross Section Library

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, D E

    2011-04-07

    This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF/B. In each case I have used my personal computer at home and publicly available data and codes. I have used these in combination to produce the temperature dependent cross sections used in applications and presented in this report. I should mention that today anyone with a personal computer can produce these results. The latest ENDF/B-VII.1 beta2 data library was recently and is now freely available through the National Nuclear Data Center (NNDC), Brookhaven National Laboratory. This release completely supersedes all preceding releases of ENDF/B. As distributed the ENDF/B-VII.1 data includes cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in our applications the ENDF/B-VII.1 library has been processed into cross sections at eight neutron reactor like temperatures, between 0 and 2100 Kelvin, in steps of 300 Kelvin (the exception being 293.6 Kelvin, for exact room temperature at 20 Celsius). It has also been processed to five astrophysics like temperatures, 1, 10, 100 eV, 1 and 10 keV. For reference purposes, 300 Kelvin is approximately 1/40 eV, so that 1 eV is approximately 12,000 Kelvin. At each temperature the cross sections are tabulated and linearly interpolable in energy. All results are in the computer independent ENDF-6 character format [R2], which allows the data to be easily transported between computers. In its processed form the POINT 2011 library is approximately 16 gigabyte in size and is distributed on one compressed DVDs (see, below for the details of the contents of each DVD).

  19. Temperature-dependent inhibition of opportunistic Vibrio pathogens by native coral commensal bacteria.

    Science.gov (United States)

    Frydenborg, Beck R; Krediet, Cory J; Teplitski, Max; Ritchie, Kim B

    2014-02-01

    Bacteria living within the surface mucus layer of corals compete for nutrients and space. A number of stresses affect the outcome of this competition. The interactions between native microorganisms and opportunistic pathogens largely determine the coral holobiont's overall health and fitness. In this study, we tested the hypothesis that commensal bacteria isolated from the mucus layer of a healthy elkhorn coral, Acropora palmata, are capable of inhibition of opportunistic pathogens, Vibrio shiloi AK1 and Vibrio coralliilyticus. These vibrios are known to cause disease in corals and their virulence is temperature dependent. Elevated temperature (30 °C) increased the cell numbers of one commensal and both Vibrio pathogens in monocultures. We further tested the hypothesis that elevated temperature favors pathogenic organisms by simultaneously increasing the fitness of vibrios and decreasing the fitness of commensals by measuring growth of each species within a co-culture over the course of 1 week. In competition experiments between vibrios and commensals, the proportion of Vibrio spp. increased significantly under elevated temperature. We finished by investigating several temperature-dependent mechanisms that could influence co-culture differences via changes in competitive fitness. The ability of Vibrio spp. to utilize glycoproteins found in A. palmata mucus increased or remained stable when exposed to elevated temperature, while commensals' tended to decrease utilization. In both vibrios and commensals, protease activity increased at 30 °C, while chiA expression increased under elevated temperatures for Vibrio spp. These results provide insight into potential mechanisms through which elevated temperature may select for pathogenic bacterial dominance and lead to disease or a decrease in coral fitness.

  20. Temperature dependent surface modification of molybdenum due to low energy He+ ion irradiation

    International Nuclear Information System (INIS)

    Tripathi, J.K.; Novakowski, T.J.; Joseph, G.; Linke, J.; Hassanein, A.

    2015-01-01

    In this paper, we report on the temperature dependent surface modifications in molybdenum (Mo) samples due to 100 eV He + ion irradiation in extreme conditions as a potential candidate to plasma-facing components in fusion devices alternative to tungsten. The Mo samples were irradiated at normal incidence, using an ion fluence of 2.6 × 10 24 ions m −2 (with a flux of 7.2 × 10 20 ions m −2 s −1 ). Surface modifications have been studied using high-resolution field emission scanning electron-(SEM) and atomic force (AFM) microscopy. At 773 K target temperature homogeneous evolution of molybdenum nanograins on the entire Mo surface were observed. However, at 823 K target temperature appearance of nano-pores and pin-holes nearby the grain boundaries, and Mo fuzz in patches were observed. The fuzz density increases significantly with target temperatures and continued until 973 K. However, at target temperatures beyond 973 K, counterintuitively, a sequential reduction in the fuzz density has been seen till 1073 K temperatures. At 1173 K and above temperatures, only molybdenum nano structures were observed. Our temperature dependent studies confirm a clear temperature widow, 823–1073 K, for Mo fuzz formation. Ex-situ high resolution X-ray photoelectron spectroscopy studies on Mo fuzzy samples show the evidence of MoO 3 3d doublets. This elucidates that almost all the Mo fuzz were oxidized during open air exposure and are thick enough as well. Likewise the microscopy studies, the optical reflectivity measurements also show a sequential reduction in the reflectivity values (i.e., enhancement in the fuzz density) up to 973 K and after then a sequential enhancement in the reflectivity values (i.e., reduction in the fuzz density) with target temperatures. This is in well agreement with microscopy studies where we observed clear temperature window for Mo fuzz growth

  1. A thermal conductivity model for nanofluids including effect of the temperature-dependent interfacial layer

    International Nuclear Information System (INIS)

    Sitprasert, Chatcharin; Dechaumphai, Pramote; Juntasaro, Varangrat

    2009-01-01

    The interfacial layer of nanoparticles has been recently shown to have an effect on the thermal conductivity of nanofluids. There is, however, still no thermal conductivity model that includes the effects of temperature and nanoparticle size variations on the thickness and consequently on the thermal conductivity of the interfacial layer. In the present work, the stationary model developed by Leong et al. (J Nanopart Res 8:245-254, 2006) is initially modified to include the thermal dispersion effect due to the Brownian motion of nanoparticles. This model is called the 'Leong et al.'s dynamic model'. However, the Leong et al.'s dynamic model over-predicts the thermal conductivity of nanofluids in the case of the flowing fluid. This suggests that the enhancement in the thermal conductivity of the flowing nanofluids due to the increase in temperature does not come from the thermal dispersion effect. It is more likely that the enhancement in heat transfer of the flowing nanofluids comes from the temperature-dependent interfacial layer effect. Therefore, the Leong et al.'s stationary model is again modified to include the effect of temperature variation on the thermal conductivity of the interfacial layer for different sizes of nanoparticles. This present model is then evaluated and compared with the other thermal conductivity models for the turbulent convective heat transfer in nanofluids along a uniformly heated tube. The results show that the present model is more general than the other models in the sense that it can predict both the temperature and the volume fraction dependence of the thermal conductivity of nanofluids for both non-flowing and flowing fluids. Also, it is found to be more accurate than the other models due to the inclusion of the effect of the temperature-dependent interfacial layer. In conclusion, the present model can accurately predict the changes in thermal conductivity of nanofluids due to the changes in volume fraction and temperature for

  2. Temperature dependent current transport of Pd/ZnO nanowire Schottky diodes

    Science.gov (United States)

    Gayen, R. N.; Bhattacharyya, S. R.; Jana, P.

    2014-09-01

    Zinc oxide (ZnO) nanowire based Schottky barrier diodes are fabricated by depositing Pd metal contact on top of vertically well-aligned ZnO nanowire arrays. A vertical array of ZnO nanowires on indium tin oxide (ITO) coated glass substrates is synthesized by hybrid wet chemical route. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) measurement confirm the formation of stoichiometric well-aligned hexagonal (h-ZnO) nanowire arrays with wurtzite structure. Temperature dependent current-voltage (I-V) measurements on palladium-ZnO (Pd/ZnO) nanowire Schottky junctions in the temperature range 303-383 K exhibit excellent rectifying character. From these nonlinear I-V plots, different electrical parameters of diode-like reverse saturation current, barrier height and ideality factor are determined as a function of temperature assuming pure thermionic emission model. The ideality factor is found to decrease while the barrier height increases with the increase in temperature. The series resistance values calculated from Cheung’s functions also show temperature dependency. Such behavior can be attributed to the presence of defects that traps carriers, and barrier height inhomogeneity at the interface of the barrier junction. After barrier height inhomogeneity correction, considering a Gaussian distributed barrier height fluctuation across the Pd/ZnO interface, the estimated values of mean barrier height and modified Richardson constant are more closely matched to the theoretically predicted value for Pd/ZnO Schottky barrier diodes. The variation of density of interface states as a function of interface state energy is also calculated.

  3. Temperature dependent power capability estimation of lithium-ion batteries for hybrid electric vehicles

    International Nuclear Information System (INIS)

    Zheng, Fangdan; Jiang, Jiuchun; Sun, Bingxiang; Zhang, Weige; Pecht, Michael

    2016-01-01

    The power capability of lithium-ion batteries affects the safety and reliability of hybrid electric vehicles and the estimate of power by battery management systems provides operating information for drivers. In this paper, lithium ion manganese oxide batteries are studied to illustrate the temperature dependency of power capability and an operating map of power capability is presented. Both parametric and non-parametric models are established in conditions of temperature, state of charge, and cell resistance to estimate the power capability. Six cells were tested and used for model development, training, and validation. Three samples underwent hybrid pulse power characterization tests at varied temperatures and were used for model parameter identification and model training. The other three were used for model validation. By comparison, the mean absolute error of the parametric model is about 29 W, and that of the non-parametric model is around 20 W. The mean relative errors of two models are 0.076 and 0.397, respectively. The parametric model has a higher accuracy in low temperature and state of charge conditions, while the non-parametric model has better estimation result in high temperature and state of charge conditions. Thus, two models can be utilized together to achieve a higher accuracy of power capability estimation. - Highlights: • The temperature dependency of power capability of lithium-ion battery is investigated. • The parametric and non-parametric power capability estimation models are proposed. • An exponential function is put forward to compensate the effects of temperature. • A comparative study on the accuracy of two models using statistical metrics is presented.

  4. Modeling Thermal Pressurization Around Shallow Dikes Using Temperature-Dependent Hydraulic Properties: Implications for Deformation Around Intrusions

    Science.gov (United States)

    Townsend, Meredith R.

    2018-01-01

    Pressurization and flow of groundwater around igneous intrusions depend in part on the hydraulic diffusivity of the host rocks and processes that enhance diffusivity, such as fracturing, or decrease diffusivity, such as mineral precipitation during chemical alteration. Characterizing and quantifying the coupled effects of alteration, pore pressurization, and deformation have significant implications for deformation around intrusions, geothermal energy, contact metamorphism, and heat transfer at mid-ocean ridges. Fractures around dikes at Ship Rock, New Mexico, indicate that pore pressures in the host rocks exceeded hydrostatic conditions by at least 15 MPa following dike emplacement. Hydraulic measurements and petrographic analysis indicate that mineral precipitation clogged the pores of the host rock, reducing porosity from 0.25 to reducing permeability by 5 orders of magnitude. Field data from Ship Rock are used to motivate and constrain numerical models for thermal pore fluid pressurization adjacent to a meter-scale dike, using temperature-dependent hydraulic properties in the host rock as a proxy for porosity loss by mineral precipitation during chemical alteration. Reduction in permeability by chemical alteration has a negligible effect on pressurization. However, reduction in porosity by mineral precipitation increases fluid pressure by constricting pore volume and is identified as a potentially significant source of pressure. A scaling relationship is derived to determine when porosity loss becomes important; if permeability is low enough, pressurization by porosity loss outweighs pressurization by thermal expansion of fluids.

  5. Photosensitive and temperature-dependent I–V characteristics of p-NiO film/n-ZnO nanorod array heterojunction diode

    Energy Technology Data Exchange (ETDEWEB)

    Long, Hao; Ai, Lei [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); Li, Songzhan [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); School of Electronic and Electrical Engineering, Wuhan Textile University, Wuhan, Hubei 430073 (China); Huang, Huihui; Mo, Xiaoming; Wang, Haoning; Chen, Zhao; Liu, Yuping [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China); Fang, Guojia, E-mail: gjfang@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072 (China)

    2014-05-01

    Highlights: • A p-NiO film/n-ZnO nanorod array heterojunction was prepared. • The heterojunction shows good morphology and crystal properties. • The diode exhibits excellent rectifying behavior. • The diode exhibits strong temperature dependent I–V properties. • The hybrid diode shows good photosensitivity under the ultraviolet irradiation. - Abstract: A p-NiO film/n-ZnO nanorod (NR) array heterojunction was prepared by deposition of NiO film on ZnO NRs using radio-frequency reactive magnetron sputtering. The well-aligned ZnO NRs were fabricated by a simple and economic hydrothermal method on a ZnO:Al-coated glass substrate. Good morphology and crystal properties of the fabricated ZnO NRs and NiO film were confirmed by scanning electron microscopy and X-ray diffraction. The p–n heterojunction exhibits excellent rectifying behaviour and strong temperature-dependent current–voltage properties in the range from −50 to 80 °C. The hybrid NR heterojunction diode shows good photosensitivity under the irradiation of 365 nm ultraviolet light. These results present potential applications in future microelectronic devices based on NiO films and the one-dimensional ZnO nanomaterials.

  6. Population Dynamics and Temperature-Dependent Development of Chrysomphalus aonidum (L.) to Aid Sustainable Pest Management Decisions.

    Science.gov (United States)

    Campolo, O; Malacrinò, A; Laudani, F; Maione, V; Zappalà, L; Palmeri, V

    2014-10-01

    The increasing worldwide trades progressively led to decreased impact of natural barriers on wild species movement. The exotic scale Chrysomphalus aonidum (L.) (Hemiptera: Diaspididae), recently reported on citrus in southern Italy, may represent a new threat to Mediterranean citriculture. We studied C. aonidum population dynamics under field conditions and documented its development under various temperatures. To enable describing temperature-dependent development through the use of linear and non-linear models, low temperature thresholds and thermal constants for each developmental stage were estimated. Chrysomphalus aonidum was able to perform four generations on green parts (leaves, sprouts) of citrus trees and three on fruits. In addition, an overall higher population density was observed on samples collected in the southern part of the tree canopy. Temperature had a significant effect on the developmental rate; female needed 625 degree days (DD) to complete its development, while male needed 833 DD. The low threshold temperatures, together with data from population dynamics, demonstrated that C. aonidum is able to overwinter as second instar and as an adult. The results obtained, validated by those collected in the field, revealed few differences between predicted and observed dates of first occurrence of each C. aonidum instar in citrus orchards. Data on C. aonidum phenology and the definition of the thermal parameters (lower and upper threshold temperatures, optimum temperature, and the thermal constant) by non-linear models could allow the estimation of the occurrence in the field of each life stage and would be helpful in developing effective integrated control strategies.

  7. Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion

    Directory of Open Access Journals (Sweden)

    Martin Gregory T

    2004-11-01

    Full Text Available Abstract Background Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. Methods We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1 surface contact heating and (2 spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. Results The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. Conclusions The heat transport system model of the

  8. Temperature dependence of microwave absorption phenomena in single and biphase soft magnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    El Kammouni, Rhimou, E-mail: elkammounirhimou@gmail.com [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Vázquez, Manuel [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Lezama, Luis [Depto. Química Inorgánica, Universidad País Vasco, UPV/EHU, Bilbao (Spain); Kurlyandskaya, Galina [Depto. Electricidad y Electrónica, Universidad País Vasco, UPV/EHU, Bilbao (Spain); Dept. Magnetism and Magnetic Nanomaterials, Ural Federal University, Ekaterinburg (Russian Federation); Kraus, Ludek [Institute of Physics, Academy of Sciences of the Czech Republic, Prague (Czech Republic)

    2014-11-15

    The microwave absorption phenomena of single and biphase magnetic microwires with soft magnetic behavior have been investigated as a function of DC applied magnetic field using two alternative techniques: (i) absorption measurements in the temperature range of 4–300 K using a spectrometer operating at X-band frequency, at 9.5 GHz, and (ii) room-temperature, RT, ferromagnetic resonance measurements in a network analyzer in the frequency range up to 20 GHz. Complementary low-frequency magnetic characterization was performed in a Vibrating Sample Magnetometer. Studies have been performed for 8 μm diameter small-magnetostriction amorphous CoFeSiB single-phase microwire, coated by micrometric Pyrex layer, and after electroplating an external shell, 2 µm or 4 µm thick, of FeNi alloys. For single phase CoFeSiB microwire, a single absorption is observed, whose DC field dependence of resonance frequency at RT fits to a Kittel-law behavior for in-plane magnetized thin film. The temperature dependence behavior shows a monotonic increase in the resonance field, H{sub r}, with temperature. A parallel reduction of the circular anisotropy field, H{sub K}, is deduced from the temperature dependence of hysteresis loops. For biphase, CoFeSiB/FeNi, microwires, the absorption phenomena at RT also follow the Kittel condition. The observed opposite evolution with temperature of resonance field, H{sub r}, in 2 and 4 µm thick FeNi samples is interpreted considering the opposite sign of magnetostriction of the respective FeNi layers. The stress-induced magnetic anisotropy field, H{sub K}, in the FeNi shell is deduced to change sign at around 130 K. - Highlights: • A single absorption phenomenon is observed for single phase CoFeSiB. • The T dependence of the microwave behavior shows a monotonic increase of H{sub r} with T. • The absorption at RT follows the Kittel condition for biphase CoFe/FeNi microwires. • The T dependence of resonant field of CoFe/FeNi is interpreted to be

  9. Observations of the temperature dependent response of ozone to NOx reductions in the Sacramento, CA urban plume

    Science.gov (United States)

    Lafranchi, B. W.; Goldstein, A. H.; Cohen, R. C.

    2011-07-01

    Observations of NOx in the Sacramento, CA region show that mixing ratios decreased by 30 % between 2001 and 2008. Here we use an observation-based method to quantify net ozone (O3) production rates in the outflow from the Sacramento metropolitan region and examine the O3 decrease resulting from reductions in NOx emissions. This observational method does not rely on assumptions about detailed chemistry of ozone production, rather it is an independent means to verify and test these assumptions. We use an instantaneous steady-state model as well as a detailed 1-D plume model to aid in interpretation of the ozone production inferred from observations. In agreement with the models, the observations show that early in the plume, the NOx dependence for Ox (Ox = O3 + NO2) production is strongly coupled with temperature, suggesting that temperature-dependent biogenic VOC emissions and other temperature-related effects can drive Ox production between NOx-limited and NOx-suppressed regimes. As a result, NOx reductions were found to be most effective at higher temperatures over the 7 year period. We show that violations of the California 1-h O3 standard (90 ppb) in the region have been decreasing linearly with decreases in NOx (at a given temperature) and predict that reductions of NOx concentrations (and presumably emissions) by an additional 30 % (relative to 2007 levels) will eliminate violations of the state 1 h standard in the region. If current trends continue, a 30 % decrease in NOx is expected by 2012, and an end to violations of the 1 h standard in the Sacramento region appears to be imminent.

  10. Experimental and theoretical investigation of temperature-dependent electrical fatigue studies on 1-3 type piezocomposites

    Directory of Open Access Journals (Sweden)

    Y. Mohan

    2016-03-01

    Full Text Available 1-3 type piezocomposites are very attractive materials for transducers and biomedical application, due to its high electromechanical coupling effects. Reliability study on 1-3 piezocomposites subjected to cyclic loading condition in transducer application is one of the primary concern. Hence, this study focuses on 1-3 piezocomposites for various PZT5A1 fiber volume fraction subjected to electrical fatigue loading up-to 106 cycles and at various elevated temperature. Initially experiments are performed on 1-3 piezocomposites, in order to understand the degradation phenomena due to various range in amplitude of electric fields (unipolar & bipolar, frequency of applied electric field and for various ambient temperature. Performing experiments for high cycle fatigue and for different fiber volume fraction of PZT5A1 is a time consuming process. Hence, a simplified macroscopic uni-axial model based on physical mechanisms of domain switching and continuum damage mechanics has been developed to predict the non-linear fatigue behaviour of 1-3 piezocomposites for temperature dependent electrical fatigue loading conditions. In this model, damage effects namely domain pinning, frozen domains and micro cracks, are considered as a damage variable (ω. Remnant variables and material properties are considered as a function of internal damage variable and the growth of the damage is derived empirically based on the experimental observation to predict the macroscopic changes in the properties. The measured material properties and dielectric hysteresis (electric displacement vs. electric field as well as butterfly curves (longitudinal strain vs. electric field are compared with the simulated results. It is observed that variation in amplitude of bipolar electric field and temperature has a strong influence on the response of 1-3 piezocomposites.

  11. Non-linear pressure/temperature-dependence of high pressure thermal inactivation of proteolytic Clostridium botulinum type B in foods.

    Directory of Open Access Journals (Sweden)

    Maximilian B Maier

    Full Text Available The effect of high pressure thermal (HPT processing on the inactivation of spores of proteolytic type B Clostridium botulinum TMW 2.357 in four differently composed low-acid foods (green peas with ham, steamed sole, vegetable soup, braised veal was studied in an industrially feasible pressure range and temperatures between 100 and 120°C. Inactivation curves exhibited rapid inactivation during compression and decompression followed by strong tailing effects. The highest inactivation (approx. 6-log cycle reduction was obtained in braised veal at 600 MPa and 110°C after 300 s pressure-holding time. In general, inactivation curves exhibited similar negative exponential shapes, but maximum achievable inactivation levels were lower in foods with higher fat contents. At high treatment temperatures, spore inactivation was more effective at lower pressure levels (300 vs. 600 MPa, which indicates a non-linear pressure/temperature-dependence of the HPT spore inactivation efficiency. A comparison of spore inactivation levels achievable using HPT treatments versus a conventional heat sterilization treatment (121.1°C, 3 min illustrates the potential of combining high pressures and temperatures to replace conventional retorting with the possibility to reduce the process temperature or shorten the processing time. Finally, experiments using varying spore inoculation levels suggested the presence of a resistant fraction comprising approximately 0.01% of a spore population as reason for the pronounced tailing effects in survivor curves. The loss of the high resistance properties upon cultivation indicates that those differences develop during sporulation and are not linked to permanent modifications at the genetic level.

  12. Temperature dependent optical characterization of Ni-TiO2 thin films as potential photocatalytic material

    Science.gov (United States)

    De, Rajnarayan; Haque, S. Maidul; Tripathi, S.; Rao, K. Divakar; Singh, Ranveer; Som, T.; Sahoo, N. K.

    2017-09-01

    Along with other transition metal doped titanium dioxide materials, Ni-TiO2 is considered to be one of the most efficient materials for catalytic applications due to its suitable energy band positions in the electronic structure. The present manuscript explores the possibility of improving the photocatalytic activity of RF magnetron sputtered Ni-TiO2 films upon heat treatment. Optical, structural and morphological and photocatalytic properties of the films have been investigated in detail for as deposited and heat treated samples. Evolution of refractive index (RI) and total film thickness as estimated from spectroscopic ellipsometry characterization are found to be in agreement with the trend in density and total film thickness estimated from grazing incidence X-ray reflectivity measurement. Interestingly, the evolution of these macroscopic properties were found to be correlated with the corresponding microstructural modifications realized in terms of anatase to rutile phase transformation and appearance of a secondary phase namely NiTiO3 at high temperature. Corresponding morphological properties of the films were also found to be temperature dependent which leads to modifications in the grain structure. An appreciable reduction of optical band gap from 2.9 to 2.5 eV of Ni-TiO2 thin films was also observed as a result of post deposition heat treatment. Testing of photocatalytic activity of the films performed under UV illumination demonstrates heat treatment under atmospheric ambience to be an effective means to enhance the photocatalytic efficiency of transition metal doped titania samples.

  13. A temperature dependent cyclic plasticity model for hot work tool steel including particle coarsening

    Science.gov (United States)

    Jilg, Andreas; Seifert, Thomas

    2018-05-01

    Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material's yield strength in highly loaded areas as e.g. in small radii in die cavities. To sustain the high loads, the hot forming tools are typically made of martensitic hot work steels. While temperatures for annealing of the tool steels usually lie in the range between 400 and 600 °C, the steels may experience even higher temperatures during hot forming, resulting in softening of the material due to coarsening of strengthening particles. In this paper, a temperature dependent cyclic plasticity model for the martensitic hot work tool steel 1.2367 (X38CrMoV5-3) is presented that includes softening due to particle coarsening and that can be applied in finite-element calculations to assess the effect of softening on the thermomechanical fatigue life of hot work tools. To this end, a kinetic model for the evolution of the mean size of secondary carbides based on Ostwald ripening is coupled with a cyclic plasticity model with kinematic hardening. Mechanism-based relations are developed to describe the dependency of the mechanical properties on carbide size and temperature. The material properties of the mechanical and kinetic model are determined on the basis of tempering hardness curves as well as monotonic and cyclic tests.

  14. Temperature Dependence of the Seebeck Coefficient in Zinc Oxide Thin Films

    Science.gov (United States)

    Noori, Amirreza; Masoumi, Saeed; Hashemi, Najmeh

    2017-12-01

    Thermoelectric devices are reliable tools for converting waste heat into electricity as they last long, produce no noise or vibration, have no moving elements, and their light weight makes them suitable for the outer space usage. Materials with high thermoelectric figure of merit (zT) have the most important role in the fabrication of efficient thermoelectric devices. Metal oxide semiconductors, specially zinc oxide has recently received attention as a material suitable for sensor, optoelectronic and thermoelectric device applications because of their wide direct bandgap, chemical stability, high-energy radiation endurance, transparency and acceptable zT. Understanding the thermoelectric properties of the undoped ZnO thin films can help design better ZnO-based devices. Here, we report the results of our experimental work on the thermoelectric properties of the undoped polycrystalline ZnO thin films. These films are deposited on alumina substrates by thermal evaporation of zinc in vacuum followed by a controlled oxidation process in air carried out at the 350-500 °C temperature range. The experimental setup including gradient heaters, thermometry system and Seebeck voltage measurement equipment for high resistance samples is described. Seebeck voltage and electrical resistivity of the samples are measured at different conditions. The observed temperature dependence of the Seebeck coefficient is discussed.

  15. Thermal analysis and temperature dependent dielectric responses of Co doped anatase TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Alamgir; Khan, Wasi; Ahammed, Nashiruddin; Naqvi, A. H.; Ahmad, Shabbir

    2015-01-01

    Nanoparticles (NPs) of pure and 5 mol % cobalt doped TiO 2 synthesized through acid modified sol-gel method were characterized to understand their thermal, structural, morphological, and temperature dependent dielectric properties. Thermogravimetric analysis (TGA) has been used for thermal studies and indicates the weight loss in two steps due to the removal of residual organics. X-ray diffraction study was employed to confirm the formation of single anatase phase with tetragonal symmetry for both pure and 5 mol % Co doped TiO 2 NPs. The average crystallite size of both samples was calculated from the Scherrer’s formula and was found in the range from 9-11 nm. TEM micrographs of these NPs reflect their shape and distribution. The dielectric constant (ε′), dielectric loss (tanδ) and ac conductivity (σ ac ) were also studied as a function of temperature at different frequencies. Electrical responses of the synthesized NPs have been analyzed carefully in the framework of relevant models. It is also noticed that the dielectric constant (ε′) of the samples found to decrease with increasing frequency but increases with increasing temperature up to a particular value and then sharply decreases. Temperature variation of dielectric constant exhibits step like escalation and shows relaxation behavior. Study of dielectric properties shows dominant dependence on the grain size as well as Co ion incorporation in TiO 2

  16. Embryonic origin of mate choice in a lizard with temperature-dependent sex determination.

    Science.gov (United States)

    Putz, Oliver; Crews, David

    2006-01-01

    Individual differences in the adult sexual behavior of vertebrates are rooted in the fetal environment. In the leopard gecko (Eublepharis macularius), a species with temperature-dependent sex determination (TSD), hatchling sex ratios differ between incubation temperatures, as does sexuality in same-sex animals. This variation can primarily be ascribed to the temperature having direct organizing actions on the brain. Here we demonstrate that embryonic temperature can affect adult mate choice in the leopard gecko. Given the simultaneous choice between two females from different incubation temperatures (30.0 and 34.0 degrees C), males from one incubation temperature (30.0 degrees C) preferred the female from 34.0 degrees C, while males from another incubation temperature (32.5 degrees C) preferred the female from 30.0 degrees C. We suggest that this difference in mate choice is due to an environmental influence on brain development leading to differential perception of opposite-sex individuals. This previously unrecognized modulator of adult mate choice lends further support to the view that mate choice is best understood in the context of an individual's entire life-history. Thus, sexual selection results from a combination of the female's as well as the male's life history. Female attractiveness and male choice therefore are complementary. Copyright 2005 Wiley Periodicals, Inc.

  17. Temperature-dependent plastic hysteresis in highly confined polycrystalline Nb films

    Science.gov (United States)

    Waheed, S.; Hao, R.; Zheng, Z.; Wheeler, J. M.; Michler, J.; Balint, D. S.; Giuliani, F.

    2018-02-01

    In this study, the effect of temperature on the cyclic deformation behaviour of a confined polycrystalline Nb film is investigated. Micropillars encapsulating a thin niobium interlayer are deformed under cyclic axial compression at different test temperatures. A distinct plastic hysteresis is observed for samples tested at elevated temperatures, whereas negligible plastic hysteresis is observed for samples tested at room temperature. These results are interpreted using planar discrete dislocation plasticity incorporating slip transmission across grain boundaries. The effect of temperature-dependent grain boundary energy and dislocation mobility on dislocation penetration and, consequently, the size of plastic hysteresis is simulated to correlate with the experimental results. It is found that the decrease in grain boundary energy barrier caused by the increase in temperature does not lead to any appreciable change in the cyclic response. However, dislocation mobility significantly affects the size of plastic hysteresis, with high mobilities leading to a larger hysteresis. Therefore, it is postulated that the experimental observations are predominantly caused by an increase in dislocation mobility as the temperature is increased above the critical temperature of body-centred cubic niobium.

  18. Temperature dependence of scintillation properties of SrMoO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailik, V.B., E-mail: vmikhai@hotmail.com [Diamond Light Source, Harwell Science Campus, Didcot OX11 0DE (United Kingdom); Elyashevskyi, Yu. [Department of Physics, University of Oxford, Keble Rd., Oxford OX1 3RH (United Kingdom); Scientific-technical and Educational Centre of Low Temperature Studies, I. Franko National University of Lviv, 50 Dragomanova Str., 79005 Lviv (Ukraine); Kraus, H. [Department of Physics, University of Oxford, Keble Rd., Oxford OX1 3RH (United Kingdom); Kim, H.J. [Department of Physics of Kyungpook National University, 1370 Sangyeok-dong, Buk-gu, Daegu 702-701 (Korea, Republic of); Kapustianyk, V.; Panasyuk, M. [Scientific-technical and Educational Centre of Low Temperature Studies, I. Franko National University of Lviv, 50 Dragomanova Str., 79005 Lviv (Ukraine)

    2015-08-21

    Studies of the X-ray luminescence and scintillation properties of a SrMoO{sub 4} crystal as function of temperature down to T=10 K have been carried out. The luminescence in SrMoO{sub 4} is quenched at room temperature, but below T<200 K the crystal exhibits a broad emission band with a maximum at a wavelength of 520 nm. The emission is attributed to the radiative decay of self-trapped excitons and defects acting as traps for the exactions at low temperatures. Such complex character of radiative decay is reflected in the kinetics which contains several components plus a contribution from delayed recombination at low temperatures. The temperature dependence of scintillation light output of SrMoO{sub 4} was studied. Comparing with a reference ZnWO{sub 4} crystal measured under the same experimental conditions it was found that the light output of SrMoO{sub 4} is 15±5%. It is suggested, therefore, that there is scope for optimisation of strontium molybdate for application as scintillator in cryogenic rare event searches.

  19. Laser-plasma sourced, temperature dependent, VUV spectrophotometer using dispersive analysis

    International Nuclear Information System (INIS)

    French, R.H.

    1990-01-01

    We have developed a vacuum ultraviolet spectrophotometer with wide energy and temperature range coverage, utilizing a laser-plasma light source (LPLS), CO 2 -laser sample heating and time-resolved dispersive analysis. Reflection and transmission spectra can be taken from 1.7 to 40 eV (31-700 nm) on samples at 15-1800 K with a time resolution of 20-400 ns. These capabilities permit the study of the temperature dependence of the electronic structure, encompassing the effects of thermal lattice expansion and electron-phonon interaction, and changes in the electronic structure associated with equilibrium and metastable phase transitions and stress relaxation. The LPLS utilizes a samarium laser-plasma created by a Q-switched Nd:YAG laser (500 mJ/pulse) to produce high brightness, stable, continuum radiation. The spectrophotometer is of a single beam design using calibrated iridium reference mirrors. White light is imaged off the sample in to the entrance slit of a 1-m polychromator. The resolution is 0.1 to 0.3 nm. The dispersed light is incident on a focal plane phosphor, fiber-optic-coupled to an image-intensified reticon detector. For spectroscopy between 300 and 1800 K, the samples are heated in situ with a 150 Watt CO 2 laser. The signal to noise ratio in the VUV, for samples at 1800 K, is excellent. From 300 K to 15 K samples are cooled using a He cryostat. (orig.)

  20. In-Flight Calibration Methods for Temperature-Dependent Offsets in the MMS Fluxgate Magnetometers

    Science.gov (United States)

    Bromund, K. R.; Plaschke, F.; Strangeway, R. J.; Anderson, B. J.; Huang, B. G.; Magnes, W.; Fischer, D.; Nakamura, R.; Leinweber, H. K.; Russell, C. T.; hide

    2016-01-01

    During the first dayside season of the Magnetospheric Multiscale (MMS) mission, the in-flight calibration process for the Fluxgate magnetometers (FGM) implemented an algorithm that selected a constant offset (zero-level) for each sensor on each orbit. This method was generally able to reduce the amplitude of residual spin tone to less than 0.2 nT within the region of interest. However, there are times when the offsets do show significant short-term variations. These variations are most prominent in the nighttime season (phase 1X), when eclipses are accompanied by offset changes as large as 1 nT. Eclipses are followed by a recovery period as long as 12 hours where the offsets continue to change as temperatures stabilize. Understanding and compensating for these changes will become critical during Phase 2 of the mission in 2017, when the nightside will become the focus of MMS science. Although there is no direct correlation between offset and temperature, the offsets are seen for the period of any given week to be well-characterized as function of instrument temperature. Using this property, a new calibration method has been developed that has proven effective in compensating for temperature-dependent offsets during phase 1X of the MMS mission and also promises to further refine calibration quality during the dayside season.