Science.gov

Sample records for accessible temperature range

  1. Natural variation in the temperature range permissive for vernalization in accessions of Arabidopsis thaliana.

    PubMed

    Wollenberg, Amanda C; Amasino, Richard M

    2012-12-01

    Vernalization is an acceleration of flowering in response to chilling, and is normally studied in the laboratory at near-freezing (2-4 °C) temperatures. Many vernalization-requiring species, such as Arabidopsis thaliana, are found in a range of habitats with varying winter temperatures. Natural variation in the temperature range that elicits a vernalization response in Arabidopsis has not been fully explored. We characterized the effect of intermediate temperatures (7-19 °C) on 15 accessions and the well-studied reference line Col-FRI. Although progressively warmer temperatures are gradually less effective at activating expression of the vernalization-specific gene VERNALIZATION-INSENSITIVE 3 (VIN3) and in accelerating flowering, there is substantial natural variation in the upper threshold (T(max) ) of the flowering-time response. VIN3 is required for the T(max) (13 °C) response of Col-FRI. Surprisingly, even 16 °C treatment caused induction of VIN3 in six tested lines, despite the ineffectiveness of this temperature in accelerating flowering for two of them. Finally, we present evidence that mild acceleration of flowering by 19 °C exposure may counterbalance the flowering time delay caused by non-inductive photoperiods in at least one accession, creating an appearance of photoperiod insensitivity.

  2. Access to warm drinking water prevents rumen temperature drop without affecting in situ NDF disappearance in grazing winter range cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ingestion of large quantities of cold water or frozen forage may result in changes in temperature of ruminal contents. Rumen microorganisms may be sensitive to temperature changes in the ruminal environment. Therefore, this study was conducted to assess the variability in ruminal temperature and e...

  3. Contrails reduce daily temperature range.

    PubMed

    Travis, David J; Carleton, Andrew M; Lauritsen, Ryan G

    2002-08-01

    The potential of condensation trails (contrails) from jet aircraft to affect regional-scale surface temperatures has been debated for years, but was difficult to verify until an opportunity arose as a result of the three-day grounding of all commercial aircraft in the United States in the aftermath of the terrorist attacks on 11 September 2001. Here we show that there was an anomalous increase in the average diurnal temperature range (that is, the difference between the daytime maximum and night-time minimum temperatures) for the period 11-14 September 2001. Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails over this period. PMID:12167846

  4. Contrails reduce daily temperature range.

    PubMed

    Travis, David J; Carleton, Andrew M; Lauritsen, Ryan G

    2002-08-01

    The potential of condensation trails (contrails) from jet aircraft to affect regional-scale surface temperatures has been debated for years, but was difficult to verify until an opportunity arose as a result of the three-day grounding of all commercial aircraft in the United States in the aftermath of the terrorist attacks on 11 September 2001. Here we show that there was an anomalous increase in the average diurnal temperature range (that is, the difference between the daytime maximum and night-time minimum temperatures) for the period 11-14 September 2001. Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails over this period.

  5. Extended temperature range rocket injector

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J. (Inventor)

    1991-01-01

    A rocket injector is provided with multiple sets of manifolds for supplying propellants to injector elements. Sensors transmit the temperatures of the propellants to a suitable controller which is operably connnected to valves between these manifolds and propellant storage tanks. When cryogenic propellant temperatures are sensed, only a portion of the valves are opened to furnish propellants to some of the manifolds. When lower temperatures are sensed, additional valves are opened to furnish propellants to more of the manifolds.

  6. Seasonal Variation in Daily Temperature Ranges.

    NASA Astrophysics Data System (ADS)

    Ruschy, David L.; Baker, Donald G.; Skaggs, Richard H.

    1991-12-01

    Abrupt spring and autumnal changes in the daily temperature range, from low winter values to higher nonwinter values, were noted in the Minneapolis-St. Paul temperature record. Since this feature was even more evident in five rural and small town Minnesota stations, it can be accepted as real.The inverse relationship found between surface albedo and the daily temperature range indicated that the reduced winter temperature range is associated with snow cover. A second factor controlling the temperature range is cloud cover. This led to the conclusion that variation in net solar radiation is the primary factor.A strong statistical relationship between daily temperature range and the three variables considered (solar radiation, albedo, and cloud cover) was limited to the spring and fall. In March-April the statistically significant factors were solar radiation and albedo, while in October-November they were solar radiation and cloud cover. For the October-December period albedo was also statistically important.

  7. Wide temperature range seal for demountable joints

    DOEpatents

    Sixsmith, H.; Valenzuela, J.A.; Nutt, W.E.

    1991-07-23

    The present invention is directed to a seal for demountable joints operating over a wide temperature range down to liquid helium temperatures. The seal has anti-extrusion guards which prevent extrusion of the soft ductile sealant material, which may be indium or an alloy thereof. 6 figures.

  8. Wide temperature range seal for demountable joints

    DOEpatents

    Sixsmith, Herbert; Valenzuela, Javier A.; Nutt, William E.

    1991-07-23

    The present invention is directed to a seal for demountable joints operating over a wide temperature range down to liquid helium temperatures. The seal has anti-extrusion guards which prevent extrusion of the soft ductile sealant material, which may be indium or an alloy thereof.

  9. Climatology: Contrails reduce daily temperature range

    NASA Astrophysics Data System (ADS)

    Travis, David J.; Carleton, Andrew M.; Lauritsen, Ryan G.

    2002-08-01

    The potential of condensation trails (contrails) from jet aircraft to affect regional-scale surface temperatures has been debated for years, but was difficult to verify until an opportunity arose as a result of the three-day grounding of all commercial aircraft in the United States in the aftermath of the terrorist attacks on 11 September 2001. Here we show that there was an anomalous increase in the average diurnal temperature range (that is, the difference between the daytime maximum and night-time minimum temperatures) for the period 11-14 September 2001. Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails over this period.

  10. Wide-Temperature-Range Integrated Operational Amplifier

    NASA Technical Reports Server (NTRS)

    Mojarradi, Mohammad; Levanas, Greg; Chen, Yuan; Kolawa, Elizabeth; Cozy, Raymond; Blalock, Benjamin; Greenwell, Robert; Terry, Stephen

    2007-01-01

    A document discusses a silicon-on-insulator (SOI) complementary metal oxide/semiconductor (CMOS) integrated- circuit operational amplifier to be replicated and incorporated into sensor and actuator systems of Mars-explorer robots. This amplifier is designed to function at a supply potential less than or equal to 5.5 V, at any temperature from -180 to +120 C. The design is implemented on a commercial radiation-hard SOI CMOS process rated for a supply potential of less than or equal to 3.6 V and temperatures from -55 to +110 C. The design incorporates several innovations to achieve this, the main ones being the following: NMOS transistor channel lengths below 1 m are generally not used because research showed that this change could reduce the adverse effect of hot carrier injection on the lifetimes of transistors at low temperatures. To enable the amplifier to withstand the 5.5-V supply potential, a circuit topology including cascade devices, clamping devices, and dynamic voltage biasing was adopted so that no individual transistor would be exposed to more than 3.6 V. To minimize undesired variations in performance over the temperature range, the transistors in the amplifier are biased by circuitry that maintains a constant inversion coefficient over the temperature range.

  11. Extended temperature range ACPS thruster investigation

    NASA Technical Reports Server (NTRS)

    Blubaugh, A. L.; Schoenman, L.

    1974-01-01

    The successful hot fire demonstration of a pulsing liquid hydrogen/liquid oxygen and gaseous hydrogen/liquid oxygen attitude control propulsion system thruster is described. The test was the result of research to develop a simple, lightweight, and high performance reaction control system without the traditional requirements for extensive periods of engine thermal conditioning, or the use of complex equipment to convert both liquid propellants to gas prior to delivery to the engine. Significant departures from conventional injector design practice were employed to achieve an operable design. The work discussed includes thermal and injector manifold priming analyses, subscale injector chilldown tests, and 168 full scale and 550 N (1250 lbF) rocket engine tests. Ignition experiments, at propellant temperatures ranging from cryogenic to ambient, led to the generation of a universal spark ignition system which can reliably ignite an engine when supplied with liquid, two phase, or gaseous propellants. Electrical power requirements for spark igniter are very low.

  12. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  13. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  14. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  15. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  16. 33 CFR 159.119 - Operability test; temperature range.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Operability test; temperature... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with inlet operating fluid temperature varying from 2 °C to 32 °C and in an ambient temperature of 50 °C with...

  17. 33 CFR 159.115 - Temperature range test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Temperature range test. 159.115...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.115 Temperature range test. (a) The device must be held at a temperature of 60 °C or higher for a period of 16 hours. (b) The...

  18. 33 CFR 159.115 - Temperature range test.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Temperature range test. 159.115...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.115 Temperature range test. (a) The device must be held at a temperature of 60 °C or higher for a period of 16 hours. (b) The...

  19. 33 CFR 159.115 - Temperature range test.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Temperature range test. 159.115...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.115 Temperature range test. (a) The device must be held at a temperature of 60 °C or higher for a period of 16 hours. (b) The...

  20. 33 CFR 159.115 - Temperature range test.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Temperature range test. 159.115...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.115 Temperature range test. (a) The device must be held at a temperature of 60 °C or higher for a period of 16 hours. (b) The...

  1. 33 CFR 159.115 - Temperature range test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Temperature range test. 159.115...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.115 Temperature range test. (a) The device must be held at a temperature of 60 °C or higher for a period of 16 hours. (b) The...

  2. Minimum Temperatures, Diurnal Temperature Ranges and Temperature Inversions in Limestone Sinkholes of Different Sizes and Shapes

    SciTech Connect

    Whiteman, Charles D.; Haiden, Thomas S.; Pospichal, Bernhard; Eisenbach, Stefan; Steinacker, Reinhold

    2004-08-01

    Air temperature data from five enclosed limestone sinkholes of various sizes and shapes on the 1300 m MSL Duerrenstein Plateau near Lunz, Austria have been analyzed to determine the effect of sinkhole geometry on temperature minima, diurnal temperature ranges, temperature inversion strengths and vertical temperature gradients. Data were analyzed for a non-snow-covered October night and for a snow-covered December night when the temperature fell as low as -28.5°C. Surprisingly, temperatures were similar in two sinkholes with very different drainage areas and depths. A three-layer model was used to show that the sky-view factor is the most important topographic parameter controlling cooling for basins in this size range and that the cooling slows when net longwave radiation at the floor of the sinkhole is nearly balanced by the ground heat flux.

  3. Optimal temperature range of a plastic species, Drosophila simulans.

    PubMed

    Austin, Christopher J; Moehring, Amanda J

    2013-05-01

    1. When a species experiences a new climate, it can adapt in two main ways: become genetically adapted to the new temperature, or adopt a plastic approach that allows it to survive at a range of temperatures. 2. The constraint on fitness for genetically adapted populations that are exposed to a new temperature has been well studied, but the range of optimal temperatures and their effect on fitness has never been examined across the worldwide distribution of a plastic species. 3. Here, we determined the optimum temperature range of 11 populations of the phenotypically plastic species Drosophila simulans. We measured the influence of temperature on eggs, larvae and adults at six temperatures that span the natural range the flies experience during their primary breeding season. We found no correlation between optimum temperature and native temperature, an effect that is not likely due to laboratory maintenance, suggesting that the species has not locally adapted to temperature. 4. We also found that this species had equal survival and reproductive success at most of the temperatures and life stages that we tested, regardless of the native temperature where the flies originated. 5. Thus, this genetically plastic species has an optimum fitness at a surprisingly wide range of temperatures, and is the first example of a cosmopolitan species exhibiting this large amount of plasticity across its sampling distribution.

  4. A Wide Range Temperature Sensor Using SOI Technology

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Elbuluk, Malik E.; Hammoud, Ahmad

    2009-01-01

    Silicon-on-insulator (SOI) technology is becoming widely used in integrated circuit chips for its advantages over the conventional silicon counterpart. The decrease in leakage current combined with lower power consumption allows electronics to operate in a broader temperature range. This paper describes the performance of an SOIbased temperature sensor under extreme temperatures and thermal cycling. The sensor comprised of a temperature-to-frequency relaxation oscillator circuit utilizing an SOI precision timer chip. The circuit was evaluated under extreme temperature exposure and thermal cycling between -190 C and +210 C. The results indicate that the sensor performed well over the entire test temperature range and it was able to re-start at extreme temperatures.

  5. Temperature inversion in long-range interacting systems

    NASA Astrophysics Data System (ADS)

    Teles, Tarcísio N.; Gupta, Shamik; Di Cintio, Pierfrancesco; Casetti, Lapo

    2015-08-01

    Temperature inversions occur in nature, e.g., in the solar corona and in interstellar molecular clouds: Somewhat counterintuitively, denser parts of the system are colder than dilute ones. We propose a simple and appealing way to spontaneously generate temperature inversions in systems with long-range interactions, by preparing them in inhomogeneous thermal equilibrium states and then applying an impulsive perturbation. In similar situations, short-range systems would typically relax to another thermal equilibrium, with a uniform temperature profile. By contrast, in long-range systems, the interplay between wave-particle interaction and spatial inhomogeneity drives the system to nonequilibrium stationary states that generically exhibit temperature inversion. We demonstrate this mechanism in a simple mean-field model and in a two-dimensional self-gravitating system. Our work underlines the crucial role the range of interparticle interaction plays in determining the nature of steady states out of thermal equilibrium.

  6. Temperature inversion in long-range interacting systems.

    PubMed

    Teles, Tarcísio N; Gupta, Shamik; Di Cintio, Pierfrancesco; Casetti, Lapo

    2015-08-01

    Temperature inversions occur in nature, e.g., in the solar corona and in interstellar molecular clouds: Somewhat counterintuitively, denser parts of the system are colder than dilute ones. We propose a simple and appealing way to spontaneously generate temperature inversions in systems with long-range interactions, by preparing them in inhomogeneous thermal equilibrium states and then applying an impulsive perturbation. In similar situations, short-range systems would typically relax to another thermal equilibrium, with a uniform temperature profile. By contrast, in long-range systems, the interplay between wave-particle interaction and spatial inhomogeneity drives the system to nonequilibrium stationary states that generically exhibit temperature inversion. We demonstrate this mechanism in a simple mean-field model and in a two-dimensional self-gravitating system. Our work underlines the crucial role the range of interparticle interaction plays in determining the nature of steady states out of thermal equilibrium.

  7. Temperature inversion in long-range interacting systems.

    PubMed

    Teles, Tarcísio N; Gupta, Shamik; Di Cintio, Pierfrancesco; Casetti, Lapo

    2015-08-01

    Temperature inversions occur in nature, e.g., in the solar corona and in interstellar molecular clouds: Somewhat counterintuitively, denser parts of the system are colder than dilute ones. We propose a simple and appealing way to spontaneously generate temperature inversions in systems with long-range interactions, by preparing them in inhomogeneous thermal equilibrium states and then applying an impulsive perturbation. In similar situations, short-range systems would typically relax to another thermal equilibrium, with a uniform temperature profile. By contrast, in long-range systems, the interplay between wave-particle interaction and spatial inhomogeneity drives the system to nonequilibrium stationary states that generically exhibit temperature inversion. We demonstrate this mechanism in a simple mean-field model and in a two-dimensional self-gravitating system. Our work underlines the crucial role the range of interparticle interaction plays in determining the nature of steady states out of thermal equilibrium. PMID:26382325

  8. Diel Surface Temperature Range Scales with Lake Size.

    PubMed

    Woolway, R Iestyn; Jones, Ian D; Maberly, Stephen C; French, Jon R; Livingstone, David M; Monteith, Donald T; Simpson, Gavin L; Thackeray, Stephen J; Andersen, Mikkel R; Battarbee, Richard W; DeGasperi, Curtis L; Evans, Christopher D; de Eyto, Elvira; Feuchtmayr, Heidrun; Hamilton, David P; Kernan, Martin; Krokowski, Jan; Rimmer, Alon; Rose, Kevin C; Rusak, James A; Ryves, David B; Scott, Daniel R; Shilland, Ewan M; Smyth, Robyn L; Staehr, Peter A; Thomas, Rhian; Waldron, Susan; Weyhenmeyer, Gesa A

    2016-01-01

    Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km2, increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored. PMID:27023200

  9. Diel Surface Temperature Range Scales with Lake Size

    PubMed Central

    Woolway, R. Iestyn; Jones, Ian D.; Maberly, Stephen C.; French, Jon R.; Livingstone, David M.; Monteith, Donald T.; Simpson, Gavin L.; Thackeray, Stephen J.; Andersen, Mikkel R.; Battarbee, Richard W.; DeGasperi, Curtis L.; Evans, Christopher D.; de Eyto, Elvira; Feuchtmayr, Heidrun; Hamilton, David P.; Kernan, Martin; Krokowski, Jan; Rimmer, Alon; Rose, Kevin C.; Rusak, James A.; Ryves, David B.; Scott, Daniel R.; Shilland, Ewan M.; Smyth, Robyn L.; Staehr, Peter A.; Thomas, Rhian; Waldron, Susan; Weyhenmeyer, Gesa A.

    2016-01-01

    Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km2, increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7°C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored. PMID:27023200

  10. Thermodynamics of Quantum Gases for the Entire Range of Temperature

    ERIC Educational Resources Information Center

    Biswas, Shyamal; Jana, Debnarayan

    2012-01-01

    We have analytically explored the thermodynamics of free Bose and Fermi gases for the entire range of temperature, and have extended the same for harmonically trapped cases. We have obtained approximate chemical potentials for the quantum gases in closed forms of temperature so that the thermodynamic properties of the quantum gases become…

  11. Braze alloy holds bonding strength over wide temperature range

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Copper-based quaternary alloys of the solid solution type is used for vacuum furnace brazing of large stainless steel components at a maximum temperature of 1975 deg F. The alloy has high bonding strength and good ductility over a temperature range extending from the cryogenic region to approximately 800 deg F.

  12. Measuring Systems for Thermometer Calibration in Low-Temperature Range

    NASA Astrophysics Data System (ADS)

    Szmyrka-Grzebyk, A.; Lipiński, L.; Manuszkiewicz, H.; Kowal, A.; Grykałowska, A.; Jancewicz, D.

    2011-12-01

    The national temperature standard for the low-temperature range between 13.8033 K and 273.16 K has been established in Poland at the Institute of Low Temperature and Structure Research (INTiBS). The standard consists of sealed cells for realization of six fixed points of the International Temperature Scale of 1990 (ITS-90) in the low-temperature range, an adiabatic cryostat and Isotech water and mercury triple-point baths, capsule standard resistance thermometers (CSPRT), and AC and DC bridges with standard resistors for thermometers resistance measurements. INTiBS calibrates CSPRTs at the low-temperature fixed points with uncertainties less than 1 mK. In lower temperature range—between 2.5 K and about 25 K — rhodium-iron (RhFe) resistance thermometers are calibrated by comparison with a standard which participated in the EURAMET.T-K1.1 comparison. INTiBS offers a calibration service for industrial platinum resistance thermometers and for digital thermometers between 77 K and 273 K. These types of thermometers may be calibrated at INTiBS also in a higher temperature range up to 550°C. The Laboratory of Temperature Standard at INTiBS acquired an accreditation from the Polish Centre for Accreditation. A management system according to EN ISO/IEC 17025:2005 was established at the Laboratory and presented on EURAMET QSM Forum.

  13. Improved Wide Operating Temperature Range of Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Bugga, Ratnakumar V.

    2013-01-01

    Future NASA missions aimed at exploring the Moon, Mars, and the outer planets require rechargeable batteries that can operate over a wide temperature range (-60 to +60 C) to satisfy the requirements of various applications including landers, rovers, penetrators, CEV, CLV, etc. This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. The Department of Energy (DoE) has identified a number of technical barriers associated with the development of Liion rechargeable batteries for PHEVs. For this reason, DoE has interest in the development of advanced electrolytes that will improve performance over a wide range of temperatures, and lead to long life characteristics (5,000 cycles over a 10-year life span). There is also interest in improving the high-voltage stability of these candidate electrolyte systems to enable the operation of up to 5 V with high specific energy cathode materials. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-40 to +40 C); however, the rate capability at the lower temperatures is very poor. In addition, the low-temperature performance typically deteriorates rapidly upon being exposed to high temperatures. A number of electrolyte formulations were developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl propionate (MP)-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalate borate) (LiBOB), which have previously been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. These MP-based electrolytes with additives have been shown to have improved performance in experiments with MCMB-LiNiCoAlO2 cells.

  14. Nylon coil actuator operating temperature range and stiffness

    NASA Astrophysics Data System (ADS)

    Kianzad, Soheil; Pandit, Milind; Bahi, Addie; Rafie Ravandi, Ali; Ko, Frank; Spinks, Geoffrey M.; Madden, John D. W.

    2015-04-01

    Components in automotive and aerospace applications require a wide temperature range of operation. Newly discovered thermally active Baughman muscle potentially provides affordable and viable solutions for driving mechanical devices by heating them from room temperature, but little is known about their operation below room temperature. We study the mechanical behavior of nylon coil actuators by testing elastic modulus and by investigating tensile stroke as a function of temperature. Loads that range from 35 MPa to 155 MPa were applied. For the nylon used and the coiling conditions, active thermal contraction totals 19.5 % when the temperature is raised from -40 °C to 160 °C. The thermal contraction observed from -40 °C to 20°C is only ~2 %, whereas between 100 and 160 °C the contraction is 10 %. A marked increase in thermal contraction is occurs in the vicinity of the glass transition temperature (~ 45°C). The elastic modulus drops as temperature increases, from ~155 MPa at - 40 °C to 35 MPa at 200 °C. Interestingly the drop in active contraction with increasing load is small and much less than might be expected given the temperature dependence of modulus.

  15. Critical temperature of a chain of long range interacting ferromagnets

    NASA Astrophysics Data System (ADS)

    del Pino, L. A.; Troncoso, P.; Curilef, S.

    2008-11-01

    The thermodynamic behavior of systems with long range interactions is anomalous, because there are some problems about defining the thermodynamic limit. A way to solve the problem is to use scaled thermodynamic quantities. In this work, we use a nonextensive scaling into Hamiltonian and characterize transitions between two different magnetic ordering phases. The critical temperature is estimated by Binder method. Ferromagnetic long range interactions are included in a special Hamiltonian through a power law that decays at large interparticle distance r as r-α for α >= 0. In addition, we improve the known nonextensive scaling and obtain the critical temperature for several values of α.

  16. Silicon device performance measurements to support temperature range enhancement

    NASA Technical Reports Server (NTRS)

    Bromstead, James; Weir, Bennett; Nelms, R. Mark; Johnson, R. Wayne; Askew, Ray

    1994-01-01

    Silicon based power devices can be used at 200 C. The device measurements made during this program show a predictable shift in device parameters with increasing temperature. No catastrophic or abrupt changes occurred in the parameters over the temperature range. As expected, the most dramatic change was the increase in leakage currents with increasing temperature. At 200 C the leakage current was in the milliAmp range but was still several orders of magnitude lower than the on-state current capabilities of the devices under test. This increase must be considered in the design of circuits using power transistors at elevated temperature. Three circuit topologies have been prototyped using MOSFET's and IGBT's. The circuits were designed using zero current or zero voltage switching techniques to eliminate or minimize hard switching of the power transistors. These circuits have functioned properly over the temperature range. One thousand hour life data have been collected for two power supplies with no failures and no significant change in operating efficiency. While additional reliability testing should be conducted, the feasibility of designing soft switched circuits for operation at 200 C has been successfully demonstrated.

  17. Fundamental problems in modern astrophysics requiring access to the ultraviolet range

    NASA Astrophysics Data System (ADS)

    Gómez de Castro, Ana I.; Lecavelier des Étangs, Alain; Reimers, Dieter

    2006-06-01

    Progress of modern astrophysics requires the access to the electromagnetic spectrum in the broadest energy range. The ultraviolet is a fundamental energy domain; warm plasmas at temperatures of 3,000-300,000 K radiate in this range, also the electronic transitions of the most abundant molecules in the Universe are in the UV. Moreover, the UV radiation field is a powerful astrochemical and photoionizing agent. Some of the most relevant problems in modern astrophysical research are related with the properties and abundance of this warm plasma in the Universe, e.g. the chemical enrichment of the Universe, the formation of the galaxies or the contribution of the InterGalactic Medium (IGM) to the total mass of the Universe. Also, this plasma is the primary tracer of some very important processes for the generation of life in our planet like the onset and stabilization of the Solar dynamo or the acceleration of organic chemistry processes in young planetary disks. This contribution represents a brief accounting of the BIG science to be carried out if new UV instrumentation becomes, eventually, available.

  18. Amplifier circuit operable over a wide temperature range

    DOEpatents

    Kelly, Ronald D.; Cannon, William L.

    1979-01-01

    An amplifier circuit having stable performance characteristics over a wide temperature range from approximately 0.degree. C up to as high as approximately 500.degree. C, such as might be encountered in a geothermal borehole. The amplifier utilizes ceramic vacuum tubes connected in directly coupled differential amplifier pairs having a common power supply and a cathode follower output stage. In an alternate embodiment, for operation up to 500.degree. C, positive and negative power supplies are utilized to provide improved gain characteristics, and all electrical connections are made by welding. Resistor elements in this version of the invention are specially heat treated to improve their stability with temperature.

  19. Increased risk of muscle tears below physiological temperature ranges

    PubMed Central

    Scott, E. E. F.; Hamilton, D. F.; Wallace, R. J.; Muir, A. Y.

    2016-01-01

    Objectives Temperature is known to influence muscle physiology, with the velocity of shortening, relaxation and propagation all increasing with temperature. Scant data are available, however, regarding thermal influences on energy required to induce muscle damage. Methods Gastrocnemius and soleus muscles were harvested from 36 male rat limbs and exposed to increasing impact energy in a mechanical test rig. Muscle temperature was varied in 5°C increments, from 17°C to 42°C (to encompass the in vivo range). The energy causing non-recoverable deformation was recorded for each temperature. A measure of tissue elasticity was determined via accelerometer data, smoothed by low-pass fifth order Butterworth filter (10 kHz). Data were analysed using one-way analysis of variance (ANOVA) and significance was accepted at p = 0.05. Results The energy required to induce muscle failure was significantly lower at muscle temperatures of 17°C to 32°C compared with muscle at core temperature, i.e., 37°C (p < 0.01). During low-energy impacts there were no differences in muscle elasticity between cold and warm muscles (p = 0.18). Differences in elasticity were, however, seen at higher impact energies (p < 0.02). Conclusion Our findings are of particular clinical relevance, as when muscle temperature drops below 32°C, less energy is required to cause muscle tears. Muscle temperatures of 32°C are reported in ambient conditions, suggesting that it would be beneficial, particularly in colder environments, to ensure that peripheral muscle temperature is raised close to core levels prior to high-velocity exercise. Thus, this work stresses the importance of not only ensuring that the muscle groups are well stretched, but also that all muscle groups are warmed to core temperature in pre-exercise routines. Cite this article: Professor A. H. R. W. Simpson. Increased risk of muscle tears below physiological temperature ranges. Bone Joint Res 2016;5:61–65. DOI: 10

  20. Alleviating a form of electric vehicle range anxiety through on-demand vehicle access

    NASA Astrophysics Data System (ADS)

    King, Christopher; Griggs, Wynita; Wirth, Fabian; Quinn, Karl; Shorten, Robert

    2015-04-01

    On-demand vehicle access is a method that can be used to reduce types of range anxiety problems related to planned travel for electric vehicle owners. Using ideas from elementary queueing theory, basic quality of service (QoS) metrics are defined to dimension a shared fleet to ensure high levels of vehicle access. Using mobility data from Ireland, it is argued that the potential cost of such a system is very low.

  1. Comment on "Temperature inversion in long-range interacting systems"

    NASA Astrophysics Data System (ADS)

    Dumin, Yurii V.

    2016-06-01

    In the recent paper by Teles et al. [Phys. Rev. E 92, 020101 (2015)], 10.1103/PhysRevE.92.020101, it was suggested that the inversed temperature profiles in various astrophysical objects—ranging from the solar corona to the interstellar molecular clouds—can be explained by the specific features of relaxation in the long-range interacting systems. Here, we show that this mechanism can really work in the self-gravitating interstellar gaseous clouds; but it is irrelevant in the solar (and stellar) coronas where stratification of density is produced by the external gravitational field.

  2. Comment on "Temperature inversion in long-range interacting systems".

    PubMed

    Dumin, Yurii V

    2016-06-01

    In the recent paper by Teles et al. [Phys. Rev. E 92, 020101 (2015)]PRESCM1539-375510.1103/PhysRevE.92.020101, it was suggested that the inversed temperature profiles in various astrophysical objects-ranging from the solar corona to the interstellar molecular clouds-can be explained by the specific features of relaxation in the long-range interacting systems. Here, we show that this mechanism can really work in the self-gravitating interstellar gaseous clouds; but it is irrelevant in the solar (and stellar) coronas where stratification of density is produced by the external gravitational field.

  3. Comment on "Temperature inversion in long-range interacting systems".

    PubMed

    Dumin, Yurii V

    2016-06-01

    In the recent paper by Teles et al. [Phys. Rev. E 92, 020101 (2015)]PRESCM1539-375510.1103/PhysRevE.92.020101, it was suggested that the inversed temperature profiles in various astrophysical objects-ranging from the solar corona to the interstellar molecular clouds-can be explained by the specific features of relaxation in the long-range interacting systems. Here, we show that this mechanism can really work in the self-gravitating interstellar gaseous clouds; but it is irrelevant in the solar (and stellar) coronas where stratification of density is produced by the external gravitational field. PMID:27415395

  4. Fluorescence temperature sensing on rotating samples in the cryogenic range

    NASA Astrophysics Data System (ADS)

    Bresson, F.; Devillers, R.

    1999-07-01

    A surface temperature measurement technique for rotating samples is proposed. It is based on the concept of fluorescence thermometry. The fluorescent and phosphorescent phenomena have been applied in thermometry for ambient and high-temperature measurement but not the cryogenic domain, which is explored using thermocouple- or platinum resistor-based thermometers. However, thermal behavior of Yb2+ ions in fluoride matrices seems to be interesting for thermometry in the range 20-120 K. We present here a remote sensing method which uses fluorescence behavior of Yb2+ ion-doped fluoride crystals. The fluorescence decay time of such crystals is related to its temperature. Since we developed a specific sol-gel process (OrMoSils) to make strongly adherent fluorescent layers, we applied the fluorescence thermometry method for rotating object surface temperature measurement. The main application is the monitoring of surface temperature of the ball bearing or turbopump axis in liquid propulsion rocket engines. Our method is presented and discussed, and we give some experimental results. An accurate calibration of the decay time of CaF2:Yb2+ versus temperature is also given.

  5. Modelling of monovacancy diffusion in W over wide temperature range

    SciTech Connect

    Bukonte, L. Ahlgren, T.; Heinola, K.

    2014-03-28

    The diffusion of monovacancies in tungsten is studied computationally over a wide temperature range from 1300 K until the melting point of the material. Our modelling is based on Molecular Dynamics technique and Density Functional Theory. The monovacancy migration barriers are calculated using nudged elastic band method for nearest and next-nearest neighbour monovacancy jumps. The diffusion pre-exponential factor for monovacancy diffusion is found to be two to three orders of magnitude higher than commonly used in computational studies, resulting in attempt frequency of the order 10{sup 15} Hz. Multiple nearest neighbour jumps of monovacancy are found to play an important role in the contribution to the total diffusion coefficient, especially at temperatures above 2/3 of T{sub m}, resulting in an upward curvature of the Arrhenius diagram. The probabilities for different nearest neighbour jumps for monovacancy in W are calculated at different temperatures.

  6. Solid oxide fuel cell operable over wide temperature range

    DOEpatents

    Baozhen, Li; Ruka, Roswell J.; Singhal, Subhash C.

    2001-01-01

    Solid oxide fuel cells having improved low-temperature operation are disclosed. In one embodiment, an interfacial layer of terbia-stabilized zirconia is located between the air electrode and electrolyte of the solid oxide fuel cell. The interfacial layer provides a barrier which controls interaction between the air electrode and electrolyte. The interfacial layer also reduces polarization loss through the reduction of the air electrode/electrolyte interfacial electrical resistance. In another embodiment, the solid oxide fuel cell comprises a scandia-stabilized zirconia electrolyte having high electrical conductivity. The scandia-stabilized zirconia electrolyte may be provided as a very thin layer in order to reduce resistance. The scandia-stabilized electrolyte is preferably used in combination with the terbia-stabilized interfacial layer. The solid oxide fuel cells are operable over wider temperature ranges and wider temperature gradients in comparison with conventional fuel cells.

  7. Large diurnal temperature range increases bird sensitivity to climate change

    PubMed Central

    Briga, Michael; Verhulst, Simon

    2015-01-01

    Climate variability is changing on multiple temporal scales, and little is known of the consequences of increases in short-term variability, particularly in endotherms. Using mortality data with high temporal resolution of zebra finches living in large outdoor aviaries (5 years, 359.220 bird-days), we show that mortality rate increases almost two-fold per 1°C increase in diurnal temperature range (DTR). Interestingly, the DTR effect differed between two groups with low versus high experimentally manipulated foraging costs, reflecting a typical laboratory ‘easy’ foraging environment and a ‘hard’ semi-natural environment respectively. DTR increased mortality on days with low minimum temperature in the easy foraging environment, but on days with high minimum temperature in the semi-natural environment. Thus, in a natural environment DTR effects will become increasingly important in a warming world, something not detectable in an ‘easy’ laboratory environment. These effects were particularly apparent at young ages. Critical time window analyses showed that the effect of DTR on mortality is delayed up to three months, while effects of minimum temperature occurred within a week. These results show that daily temperature variability can substantially impact the population viability of endothermic species. PMID:26563993

  8. Large diurnal temperature range increases bird sensitivity to climate change.

    PubMed

    Briga, Michael; Verhulst, Simon

    2015-01-01

    Climate variability is changing on multiple temporal scales, and little is known of the consequences of increases in short-term variability, particularly in endotherms. Using mortality data with high temporal resolution of zebra finches living in large outdoor aviaries (5 years, 359.220 bird-days), we show that mortality rate increases almost two-fold per 1°C increase in diurnal temperature range (DTR). Interestingly, the DTR effect differed between two groups with low versus high experimentally manipulated foraging costs, reflecting a typical laboratory 'easy' foraging environment and a 'hard' semi-natural environment respectively. DTR increased mortality on days with low minimum temperature in the easy foraging environment, but on days with high minimum temperature in the semi-natural environment. Thus, in a natural environment DTR effects will become increasingly important in a warming world, something not detectable in an 'easy' laboratory environment. These effects were particularly apparent at young ages. Critical time window analyses showed that the effect of DTR on mortality is delayed up to three months, while effects of minimum temperature occurred within a week. These results show that daily temperature variability can substantially impact the population viability of endothermic species. PMID:26563993

  9. Large diurnal temperature range increases bird sensitivity to climate change.

    PubMed

    Briga, Michael; Verhulst, Simon

    2015-11-13

    Climate variability is changing on multiple temporal scales, and little is known of the consequences of increases in short-term variability, particularly in endotherms. Using mortality data with high temporal resolution of zebra finches living in large outdoor aviaries (5 years, 359.220 bird-days), we show that mortality rate increases almost two-fold per 1°C increase in diurnal temperature range (DTR). Interestingly, the DTR effect differed between two groups with low versus high experimentally manipulated foraging costs, reflecting a typical laboratory 'easy' foraging environment and a 'hard' semi-natural environment respectively. DTR increased mortality on days with low minimum temperature in the easy foraging environment, but on days with high minimum temperature in the semi-natural environment. Thus, in a natural environment DTR effects will become increasingly important in a warming world, something not detectable in an 'easy' laboratory environment. These effects were particularly apparent at young ages. Critical time window analyses showed that the effect of DTR on mortality is delayed up to three months, while effects of minimum temperature occurred within a week. These results show that daily temperature variability can substantially impact the population viability of endothermic species.

  10. Examining the spring discontinuity in daily temperature ranges

    SciTech Connect

    Schwartz, M.D.

    1996-04-01

    The atmosphere and biosphere both change rapidly throughout midlatitude spring. Many weather variables are modified during this season, including the diurnal temperature range (DTR). The mean DTR trend displays a discontinuity at the onset of spring characterized by a rapid increase for several weeks, followed by an abrupt leveling off. The trend then remains essentially flat throughout the remainder of the warm season. These DTR changes reflect the interactive role many weather variables play with surface-layer processes. Thus, diagnosing the causes of these variations may provide background information for numerous global change analyses, as daily temperature data become increasingly available worldwide. The results of this study suggest that several factors (snow cover loss, more frequent southerly winds, and increased ceiling heights) are responsible for the initial rapid increase in the DTR. The second half of the discontinuity (subsequent leveling off) is connected with increased atmospheric moisture and coincides with the onset of plant transpiration. 14 refs., 5 figs, 2 tabs.

  11. The association between diurnal temperature range and childhood bacillary dysentery

    NASA Astrophysics Data System (ADS)

    Wen, Li-ying; Zhao, Ke-fu; Cheng, Jian; Wang, Xu; Yang, Hui-hui; Li, Ke-sheng; Xu, Zhi-wei; Su, Hong

    2016-02-01

    Previous studies have found that mean, maximum, and minimum temperatures were associated with bacillary dysentery (BD). However, little is known about whether the within-day variation of temperature has any impact on bacillary dysentery. The current study aimed to identify the relationship between diurnal temperature range (DTR) and BD in Hefei, China. Daily data on BD counts among children aged 0-14 years from 1 January 2006 to 31 December 2012 were retrieved from Hefei Center for Disease Control and Prevention. Daily data on ambient temperature and relative humidity covering the same period were collected from the Hefei Bureau of Meteorology. A Poisson generalized linear regression model combined with a distributed lag non-linear model (DLNM) was used in the analysis after controlling the effects of season, long-term trends, mean temperature, and relative humidity. The results showed that there existed a statistically significant relationship between DTR and childhood BD. The DTR effect on childhood bacillary dysentery increased when DTR was over 8 °C. And it was greatest at 1-day lag, with an 8 % (95 % CI = 2.9-13.4 %) increase of BD cases per 5 °C increment of DTR. Male children and children aged 0-5 years appeared to be more vulnerable to the DTR effect. The data indicate that large DTR may increase the incidence of childhood BD. Caregivers and health practitioners should be made aware of the potential threat posed by large DTR. Therefore, DTR should be taken into consideration when making targeted health policies and programs to protect children from being harmed by climate impacts.

  12. The association between diurnal temperature range and childhood bacillary dysentery.

    PubMed

    Wen, Li-ying; Zhao, Ke-fu; Cheng, Jian; Wang, Xu; Yang, Hui-hui; Li, Ke-sheng; Xu, Zhi-wei; Su, Hong

    2016-02-01

    Previous studies have found that mean, maximum, and minimum temperatures were associated with bacillary dysentery (BD). However, little is known about whether the within-day variation of temperature has any impact on bacillary dysentery. The current study aimed to identify the relationship between diurnal temperature range (DTR) and BD in Hefei, China. Daily data on BD counts among children aged 0-14 years from 1 January 2006 to 31 December 2012 were retrieved from Hefei Center for Disease Control and Prevention. Daily data on ambient temperature and relative humidity covering the same period were collected from the Hefei Bureau of Meteorology. A Poisson generalized linear regression model combined with a distributed lag non-linear model (DLNM) was used in the analysis after controlling the effects of season, long-term trends, mean temperature, and relative humidity. The results showed that there existed a statistically significant relationship between DTR and childhood BD. The DTR effect on childhood bacillary dysentery increased when DTR was over 8 °C. And it was greatest at 1-day lag, with an 8% (95% CI = 2.9-13.4%) increase of BD cases per 5 °C increment of DTR. Male children and children aged 0-5 years appeared to be more vulnerable to the DTR effect. The data indicate that large DTR may increase the incidence of childhood BD. Caregivers and health practitioners should be made aware of the potential threat posed by large DTR. Therefore, DTR should be taken into consideration when making targeted health policies and programs to protect children from being harmed by climate impacts.

  13. Changes in diurnal temperature range and national cereal yields

    SciTech Connect

    Lobell, D

    2007-04-26

    Models of yield responses to temperature change have often considered only changes in average temperature (Tavg), with the implicit assumption that changes in the diurnal temperature range (DTR) can safely be ignored. The goal of this study was to evaluate this assumption using a combination of historical datasets and climate model projections. Data on national crop yields for 1961-2002 in the 10 leading producers of wheat, rice, and maize were combined with datasets on climate and crop locations to evaluate the empirical relationships between Tavg, DTR, and crop yields. In several rice and maize growing regions, including the two major nations for each crop, there was a clear negative response of yields to increased DTR. This finding reflects a nonlinear response of yields to temperature, which likely results from greater water and heat stress during hot days. In many other cases, the effects of DTR were not statistically significant, in part because correlations of DTR with other climate variables and the relatively short length of the time series resulted in wide confidence intervals for the estimates. To evaluate whether future changes in DTR are relevant to crop impact assessments, yield responses to projected changes in Tavg and DTR by 2046-2065 from 11 climate models were estimated. The mean climate model projections indicated an increase in DTR in most seasons and locations where wheat is grown, mixed projections for maize, and a general decrease in DTR for rice. These mean projections were associated with wide ranges that included zero in nearly all cases. The estimated impacts of DTR changes on yields were generally small (<5% change in yields) relative to the consistently negative impact of projected warming of Tavg. However, DTR changes did significantly affect yield responses in several cases, such as in reducing US maize yields and increasing India rice yields. Because DTR projections tend to be positively correlated with Tavg, estimates of yields

  14. Accessing Recent Trend of Land Surface Temperature from Satellite Observations

    NASA Astrophysics Data System (ADS)

    Shen, S.; Leptoukh, G. G.; Romanov, P.

    2011-12-01

    Land surface temperature (LST) is an important element to measure the state of the terrestrial ecosystems and to study the surface energy budgets. In support of the land cover/land use change related international program MAIRS (Monsoon Asia Integrated Regional Study), we have collected the global monthly LST measured by MODIS since the beginning of the missions. The MODIS LST time series have ~11 years of data from Terra since 2000 and ~9 years of data from Aqua since 2002, which makes possible to study the recent climate, such as trend and variability. In this study, monthly climatology from two satellite platforms are calculated and compared. The spatial patterns of LST trends are accessed, focusing on the Asian Monsoon region. Furthermore, the MODIS LST trends are compared with the skin temperature trend from the NASA's atmospheric assimilation model, MERRA (MODERN ERA RETROSPECTIVE-ANALYSIS FOR RESEARCH AND APPLICATIONS), which has longer data record since 1979. The calculated climatology and anomaly of MODIS LST will be integrated into the online visualization system, Giovanni, at NASA GES DISC for easy access and use by scientists and general public.

  15. Iterative matrix inversion technique for simultaneous strain and temperature sensing in an extended temperature range

    NASA Astrophysics Data System (ADS)

    Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

    2016-05-01

    The linear matrix approach is the common method for multi-parameter FBG-based strain and temperature sensing. As it does not include non-linear temperature responses and hence lacks accuracy, the application of an iterative matrix inversion technique can be used to remedy this deficiency. Employing this method in a set-up using a multi-parameter sensor system that consists of two FBGs in fibers, which differ in cladding diameters, significantly reduced temperature uncertainties of +/- 1°C could be achieved within a temperature range between -20°C and 150°C.

  16. A high-precision carbon-13 shift thermometer for the temperature range 100-300 K

    PubMed

    Quast; Heubes; Dunger; Limbach

    1998-10-01

    The first carbon-13 shift thermometer for the temperature range of 100-300 K is based on the very rapid equilibration of a pair of semibullvalene valence tautomers. The temperature dependence of the equilibrium constant is reflected in strongly temperature-dependent shift differences Deltadelta between averaged signals, e.g., d(Deltadelta)/dT = 0.051 ppm K-1 at 300, 0.087 ppm K-1 at 200, and 0. 175 ppm K-1 at 110 K for the quaternary carbon atoms C2 and C6. At 37 temperatures T, which were measured with calibrated platinum resistance thermometers, shift differences Deltadelta were taken from nondecoupled carbon-13 spectra recorded from solutions of 1 in mixtures of chlorodifluoromethane and deuterated dimethyl ether without spinning. The least-squares fit of these Deltadelta vs T data to a polynomial equation of the fourth degree (Eq. [5], r2 = 0. 9999) allows the calculation of temperatures from measured shift differences with a standard deviation of 0.46 K and an estimated error of about 1 K. The heating effects of WALTZ-16 decoupling and the influence of solvents on Deltadelta are investigated. A comparison with existing NMR thermometers demonstrates the superior performance of the new carbon-13 shift thermometer with respect to precision and the accessible temperature range. Copyright 1998 Academic Press.

  17. A High-Precision Carbon-13 Shift Thermometer for the Temperature Range 100 300 K

    NASA Astrophysics Data System (ADS)

    Quast, Helmut; Heubes, Markus; Dunger, Anita; Limbach, Hans-Heinrich

    1998-10-01

    The first carbon-13 shift thermometer for the temperature range of 100-300 K is based on the very rapid equilibration of a pair of semibullvalene valence tautomers. The temperature dependence of the equilibrium constant is reflected in strongly temperature-dependent shift differences Δδ between averaged signals, e.g.,d(Δδ)/dT= 0.051 ppm K-1at 300, 0.087 ppm K-1at 200, and 0.175 ppm K-1at 110 K for the quaternary carbon atoms C2 and C6. At 37 temperaturesT, which were measured with calibrated platinum resistance thermometers, shift differences Δδ were taken from nondecoupled carbon-13 spectra recorded from solutions of 1 in mixtures of chlorodifluoromethane and deuterated dimethyl ether without spinning. The least-squares fit of these Δδ vsTdata to a polynomial equation of the fourth degree (Eq. [5],r2= 0.9999) allows the calculation of temperatures from measured shift differences with a standard deviation of 0.46 K and an estimated error of about 1 K. The heating effects of WALTZ-16 decoupling and the influence of solvents on Δδ are investigated. A comparison with existing NMR thermometers demonstrates the superior performance of the new carbon-13 shift thermometer with respect to precision and the accessible temperature range.

  18. Temperature effects on failure and annealing behavior in dynamic random access memories

    NASA Astrophysics Data System (ADS)

    Wilkin, N. D.; Self, C. T.

    1982-12-01

    Total dose failure levels and long time anneal characteristics of dynamic random access memories are measured while the devices are exercised under actual use conditions. These measurements were performed over the temperature range of -60 C to +70 C. The total dose failure levels are shown to decrease with increasing temperature. The anneal characteristics are shown to result in both an increase and decrease in the measured number of errors as a function of time. Finally a description of the test instrumentation and irradiation procedures are given.

  19. Analysis of trends in maximum and minimum temperature, diurnal temperature range, and cloud cover over India

    NASA Astrophysics Data System (ADS)

    Roy, Shouraseni Sen; Balling, Robert C.

    2005-06-01

    We assembled data at a 1° latitude by 1° longitude resolution for 285 cells across India and analyzed the seasonal trends in the maximum and minimum temperature, diurnal temperature range (DTR), and cloud cover for the time period 1931-2002. Significant increases in maximum and minimum temperature have occurred over the Deccan plateau, but in general, trends in DTR were not significant except for a decrease in northwest Kashmir in summer. The effect of cloud cover on the DTR was expectedly negative for most of the country for winter and summer seasons with significant increase in summer cloud cover in Kashmir.

  20. Long-Range Correlations of Global Sea Surface Temperature

    PubMed Central

    Jiang, Lei; Zhao, Xia; Wang, Lu

    2016-01-01

    Scaling behaviors of the global monthly sea surface temperature (SST) derived from 1870–2009 average monthly data sets of Hadley Centre Sea Ice and SST (HadISST) are investigated employing detrended fluctuation analysis (DFA). The global SST fluctuations are found to be strong positively long-range correlated at all pertinent time-intervals. The value of scaling exponent is larger in the tropics than those in the intermediate latitudes of the northern and southern hemispheres. DFA leads to the scaling exponent α = 0.87 over the globe (60°S~60°N), northern hemisphere (0°N~60°N), and southern hemisphere (0°S~60°S), α = 0.84 over the intermediate latitude of southern hemisphere (30°S~60°S), α = 0.81 over the intermediate latitude of northern hemisphere (30°N~60°N) and α = 0.90 over the tropics 30°S~30°N [fluctuation F(s) ~ sα], which the fluctuations of monthly SST anomaly display long-term correlated behaviors. Furthermore, the larger the standard deviation is, the smaller long-range correlations (LRCs) of SST in the corresponding regions, especially in three distinct upwelling areas. After the standard deviation is taken into account, an index χ = α * σ is introduced to obtain the spatial distributions of χ. There exists an obvious change of global SST in central east and northern Pacific and the northwest Atlantic. This may be as a clue on predictability of climate and ocean variabilities. PMID:27100397

  1. Hydrogen-atmosphere induction furnace has increased temperature range

    NASA Technical Reports Server (NTRS)

    Caves, R. M.; Gresslin, C. H.

    1966-01-01

    Improved hydrogen-atmosphere induction furnace operates at temperatures up to 5,350 deg F. The furnace heats up from room temperature to 4,750 deg F in 30 seconds and cools down to room temperature in 2 minutes.

  2. Accessing Recent Trend of Land Surface Temperature from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Shen, Suhung; Leptoukh, Gregory G.; Romanov, Peter

    2011-01-01

    Land surface temperature (Ts) is an important element to measure the state of terrestrial ecosystems and to study surface energy budgets. In support of the land cover/land use change-related international program MAIRS (Monsoon Asia Integrated Regional Study), we have collected global monthly Ts measured by MODIS since the beginning of the missions. The MODIS Ts time series have approximately 11 years of data from Terra since 2000 and approximately 9 years of data from Aqua since 2002, which makes possible to study the recent climate, such as trend. In this study, monthly climatology from two platforms are calculated and compared with that from AIRS. The spatial patterns of Ts trends are accessed, focusing on the Eurasia region. Furthermore, MODIS Ts trends are compared with those from AIRS and NASA's atmospheric assimilation model, MERRA (Modern Era Retrospective-analysis for Research and Applications). The preliminary results indicate that the recent 8-year Ts trend shows an oscillation-type spatial variation over Eurasia. The pattern is consistent for data from MODIS, AIRS, and MERRA, with the positive center over Eastern Europe, and the negative center over Central Siberia. The calculated climatology and anomaly of MODIS Ts will be integrated into the online visualization system, Giovanni, at NASA GES DISC for easy use by scientists and general public.

  3. Optical fiber voltage sensors for broad temperature ranges

    NASA Technical Reports Server (NTRS)

    Rose, A. H.; Day, G. W.

    1992-01-01

    We describe the development of an optical fiber ac voltage sensor for aircraft and spacecraft applications. Among the most difficult specifications to meet for this application is a temperature stability of +/- 1 percent from -65 C to +125 C. This stability requires a careful selection of materials, components, and optical configuration with further compensation using an optical-fiber temperature sensor located near the sensing element. The sensor is a polarimetric design, based on the linear electro-optic effect in bulk Bi4Ge3O12. The temperature sensor is also polarimetric, based on the temperature dependence of the birefringence of bulk SiO2. The temperature sensor output is used to automatically adjust the calibration of the instrument.

  4. Ultrasonic Multiple-Access Ranging System Using Spread Spectrum and MEMS Technology for Indoor Localization

    PubMed Central

    Segers, Laurent; Tiete, Jelmer; Braeken, An; Touhafi, Abdellah

    2014-01-01

    Indoor localization of persons and objects poses a great engineering challenge. Previously developed localization systems demonstrate the use of wideband techniques in ultrasound ranging systems. Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy. A novel ranging method using the frequency hopping spread spectrum with finite impulse response filtering will be investigated and compared against the direct sequence spread spectrum. In the first setup, distances are estimated in a single-access environment, while in the second setup, two senders and one receiver are used. During the experiments, the micro-electromechanical systems are used as ultrasonic sensors, while the senders were implemented using field programmable gate arrays. Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum. When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum. PMID:24553084

  5. Extended temperature range studies for dry heat microbial reduction

    NASA Technical Reports Server (NTRS)

    Kempf, Michael; Kirschner, Larry; Beaudet, Robert A.

    2005-01-01

    This paper will present the lethality data that has been collected at this time and the planned future studies. The results show that rapid ramp-up heating times are critical to obtaining valid lethality data at high temperatures because an extensive number of spores are killed before reaching the target temperature. Exploratory experiments have also been performed using a laser to rapidly heat coupons.

  6. An Ultrasonic Multiple-Access Ranging Core Based on Frequency Shift Keying Towards Indoor Localization.

    PubMed

    Segers, Laurent; Van Bavegem, David; De Winne, Sam; Braeken, An; Touhafi, Abdellah; Steenhaut, Kris

    2015-07-30

    This paper describes a new approach and implementation methodology for indoor ranging based on the time difference of arrival using code division multiple access with ultrasound signals. A novel implementation based on a field programmable gate array using finite impulse response filters and an optimized correlation demodulator implementation for ultrasound orthogonal signals is developed. Orthogonal codes are modulated onto ultrasound signals using frequency shift keying with carrier frequencies of 24.5 kHz and 26 kHz. This implementation enhances the possibilities for real-time, embedded and low-power tracking of several simultaneous transmitters. Due to the high degree of parallelism offered by field programmable gate arrays, up to four transmitters can be tracked simultaneously. The implementation requires at most 30% of the available logic gates of a Spartan-6 XC6SLX45 device and is evaluated on accuracy and precision through several ranging topologies. In the first topology, the distance between one transmitter and one receiver is evaluated. Afterwards, ranging analyses are applied between two simultaneous transmitters and one receiver. Ultimately, the position of the receiver against four transmitters using trilateration is also demonstrated. Results show enhanced distance measurements with distances ranging from a few centimeters up to 17 m, while keeping a centimeter-level accuracy.

  7. An Ultrasonic Multiple-Access Ranging Core Based on Frequency Shift Keying Towards Indoor Localization

    PubMed Central

    Segers, Laurent; Van Bavegem, David; De Winne, Sam; Braeken, An; Touhafi, Abdellah; Steenhaut, Kris

    2015-01-01

    This paper describes a new approach and implementation methodology for indoor ranging based on the time difference of arrival using code division multiple access with ultrasound signals. A novel implementation based on a field programmable gate array using finite impulse response filters and an optimized correlation demodulator implementation for ultrasound orthogonal signals is developed. Orthogonal codes are modulated onto ultrasound signals using frequency shift keying with carrier frequencies of 24.5 kHz and 26 kHz. This implementation enhances the possibilities for real-time, embedded and low-power tracking of several simultaneous transmitters. Due to the high degree of parallelism offered by field programmable gate arrays, up to four transmitters can be tracked simultaneously. The implementation requires at most 30% of the available logic gates of a Spartan-6 XC6SLX45 device and is evaluated on accuracy and precision through several ranging topologies. In the first topology, the distance between one transmitter and one receiver is evaluated. Afterwards, ranging analyses are applied between two simultaneous transmitters and one receiver. Ultimately, the position of the receiver against four transmitters using trilateration is also demonstrated. Results show enhanced distance measurements with distances ranging from a few centimeters up to 17 m, while keeping a centimeter-level accuracy. PMID:26263986

  8. Influence of ambient temperature and diurnal temperature range on incidence of cardiac arrhythmias

    NASA Astrophysics Data System (ADS)

    Kim, Jayeun; Kim, Ho

    2016-08-01

    We investigated the association between ambient temperature and diurnal temperature range (DTR) and the exacerbation of arrhythmia symptoms, using data from 31,629 arrhythmia-related emergency department (ED) visits in Seoul, Korea. Linear regression analyses with allowances for over-dispersion were applied to temperature variables and ED visits, adjusted for various environmental factors. The effects were expressed as percentage changes in the risk of arrhythmia-related ED visits up to 5 days later, with 95 % confidence intervals (CI), per 1 °C increase in DTR and 1 °C decrease in mean temperature. The overall risk of ED visits increased by 1.06 % (95 % CI 0.39 %, 1.73 %) for temperature and by 1.84 % (0.34, 3.37 %) for DTR. A season-specific effect was detected for temperature during both fall (1.18 % [0.01, 2.37 %]) and winter (0.87 % [0.07, 1.67 %]), and for DTR during spring (3.76 % [0.34, 7.29 %]). Females were more vulnerable, with 1.57 % [0.56, 2.59 %] and 3.84 % [1.53, 6.20 %] for the changes in temperature and DTR, respectively. An age-specific effect was detected for DTR, with 3.13 % [0.95, 5.36 %] for age ≥ 65 years, while a greater increased risk with temperature decrease was observed among those aged <65 (1.08 % [0.17, 2.00 %]) than among those aged ≥65 (1.02 % [0.06, 1.99 %]). Cardiac arrest was inversely related with temperature (1.61 % [0.46, 2.79 %]), while other cardiac arrhythmias depended more on the change in DTR (4.72 % [0.37, 9.26 %]). These findings provide evidence that low-temperature and elevated DTR influence the occurrence of arrhythmia exacerbations or symptoms, suggesting a possible strategy for reducing risk by encouraging vulnerable populations to minimize exposure.

  9. Wide temperature range testing with ROTEM coagulation analyses.

    PubMed

    Kander, Thomas; Brokopp, Jens; Friberg, Hans; Schött, Ulf

    2014-09-01

    Mild induced hypothermia is used for neuroprotection in patients successfully resuscitated after cardiac arrest. Temperature-dependent effects on rotational thromboelastometry (ROTEM(®)) assays with EXTEM(®), FIBTEM(®), or APTEM(®) in cardiac arrest patients have not previously been studied. Ten patients with out-of-hospital cardiac arrest who underwent induced hypothermia were studied during stable hypothermia at 33°C. ROTEM temperature effects on EXTEM, FIBTEM, and APTEM assays were studied at temperatures set between 30°C and 42°C. Citrated whole blood test tubes were incubated in temperature-adjusted heating blocks and then investigated at respective temperature in the temperature-adjusted ROTEM. The following variables were determined: clotting time (CT), clot formation time (CFT), α-angle, and maximum clot firmness (MCF). The results from hypo- and hyperthermia samples were compared with the samples incubated at 37°C using the Wilcoxon matched-pairs signed-rank test. A p-value of <0.05 was considered significant. CT-EXTEM(®) and CT-APTEM(®) were prolonged by hypothermia at 30°C (p<0.01 for both) and 33°C (p<0.05 for both). Hyperthermia at 42°C shortened CT-EXTEM (p<0.05) and CT-APTEM (p<0.01). CFT-EXTEM(®) and CFT-APTEM(®) were markedly prolonged by hypothermia at 30°C, 33°C, and 35°C (p<0.01 for all except CFT-EXTEM, 35°C [p<0.05]). The α-angle-EXTEM was markedly decreased at 30°C, 33°C, and 35°C (p<0.01) but increased at 40°C (p<0.05) and 42°C (p<0.01); α-angle-APTEM showed similar results. MCF was unchanged at different temperatures for all tests. ROTEM (EXTEM, FIBTEM, and APTEM assays) revealed a hypocoagulative response to in vitro-applied hypothermia in the blood of cardiac arrest patients reflected in the prolonged clot initiation and decreased clot propagation. Hyperthermia showed the opposite effects. Clot firmness was not affected by temperature.

  10. Water temperature impacts water consumption by range cattle in winter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water consumption and DMI have been found to be positively correlated, which may interact with ingestion of cold water or grazed frozen forage due to transitory reductions in temperature of ruminal contents. The hypothesis underpinning the study explores the potential that cows provided warm drinkin...

  11. Gap/silicon Tandem Solar Cell with Extended Temperature Range

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A. (Inventor)

    2006-01-01

    A two-junction solar cell has a bottom solar cell junction of crystalline silicon, and a top solar cell junction of gallium phosphide. A three (or more) junction solar cell has bottom solar cell junctions of silicon, and a top solar cell junction of gallium phosphide. The resulting solar cells exhibit improved extended temperature operation.

  12. A short-range objective nocturnal temperature forecasting model

    NASA Technical Reports Server (NTRS)

    Sutherland, R. A.

    1980-01-01

    A relatively simple, objective, nocturnal temperature forecasting model suitable for freezing and near-freezing conditions has been designed so that a user, presumably a weather forecaster, can put in standard meteorological data at a particular location and receive an hour-by-hour prediction of surface and air temperatures for that location for an entire night. The user has the option of putting in his own estimates of wind speeds and background sky radiation which are treated as independent variables. An analysis of 141 test runs show that 57.4% of the time the model predicts to within 1 C for the best cases and to within 3 C for 98.0% of all cases.

  13. Zero-Temperature Fluctuations in Short-Range Spin Glasses

    NASA Astrophysics Data System (ADS)

    Arguin, L.-P.; Newman, C. M.; Stein, D. L.; Wehr, J.

    2016-06-01

    We consider the energy difference restricted to a finite volume for certain pairs of incongruent ground states (if they exist) in the d-dimensional Edwards-Anderson Ising spin glass at zero temperature. We prove that the variance of this quantity with respect to the couplings grows proportionally to the volume in any d ≥ 2. An essential aspect of our result is the use of the excitation metastate. As an illustration of potential applications, we use this result to restrict the possible structure of spin glass ground states in two dimensions.

  14. Satellite range delay simulator for a matrix-switched time division multiple-access network simulator

    NASA Technical Reports Server (NTRS)

    Nagy, Lawrence A.

    1989-01-01

    The Systems Integration, Test, and Evaluation (SITE) facility at NASA Lewis Research Center is presently configured as a satellite-switched time division multiple access (SS-TDMA) network simulator. The purpose of SITE is to demonstrate and evaluate advanced communication satellite technologies, presently embodied by POC components developed under NASA contracts in addition to other hardware, such as ground terminals, designed and built in-house at NASA Lewis. Each ground terminal in a satellite communications system will experience a different aspect of the satellite's motion due mainly to daily tidal effects and station keeping, hence a different duration and rate of variation in the range delay. As a result of this and other effects such as local oscillator instability, each ground terminal must constantly adjust its transmit burst timing so that data bursts from separate ground terminals arrive at the satellite in their assigned time slots, preventing overlap and keeping the system in synchronism. On the receiving end, ground terminals must synchronize their local clocks using reference transmissions received through the satellite link. A feature of the SITE facility is its capability to simulate the varying propagation delays and associated Doppler frequency shifts that the ground terminals in the network have to cope with. Delay is achieved by means of two NASA Lewis designed and built range delay simulator (RDS) systems, each independently controlled locally with front panel switches or remotely by an experiment control and monitor (EC/M) computer.

  15. Long-Range Distance Measurements in Proteins at Physiological Temperatures Using Saturation Recovery EPR Spectroscopy

    PubMed Central

    2015-01-01

    Site-directed spin labeling in combination with EPR is a powerful method for providing distances on the nm scale in biological systems. The most popular strategy, double electron–electron resonance (DEER), is carried out at cryogenic temperatures (50–80 K) to increase the short spin–spin relaxation time (T2) upon which the technique relies. A challenge is to measure long-range distances (20–60 Å) in proteins near physiological temperatures. Toward this goal we are investigating an alternative approach based on the distance-dependent enhancement of spin–lattice relaxation rate (T1–1) of a nitroxide spin label by a paramagnetic metal. With a commonly used nitroxide side chain (R1) and Cu2+, it has been found that interspin distances ≤25 Å can be determined in this way (Jun et al. Biochemistry2006, 45, 11666). Here, the upper limit of the accessible distance is extended to ≈40 Å using spin labels with long T1, a high-affinity 5-residue Cu2+ binding loop inserted into the protein sequence, and pulsed saturation recovery to measure relaxation enhancement. Time-domain Cu2+ electron paramagnetic resonance, quantum mechanical calculations, and molecular dynamics simulations provide information on the structure and geometry of the Cu2+ loop and indicate that the metal ion is well-localized in the protein. An important aspect of these studies is that both Cu2+/nitroxide DEER at cryogenic temperatures and T1 relaxation measurements at room temperature can be carried out on the same sample, allowing both validation of the relaxation method and assessment of the effect of freezing on protein structure. PMID:25290172

  16. Heart rate, multiple body temperature, long-range and long-life telemetry system for free-ranging animals

    NASA Technical Reports Server (NTRS)

    Lund, G. F.; Westbrook, R. M.; Fryer, T. B.

    1980-01-01

    The design details and rationale for a versatile, long-range, long-life telemetry data acquisition system for heart rates and body temperatures at multiple locations from free-ranging animals are presented. The design comprises an implantable transmitter for short to medium range transmission, a receiver retransmitter collar to be worn for long-range transmission, and a signal conditioner interface circuit to assist in signal discrimination and demodulation of receiver or tape-recorded audio outputs. Implanted electrodes are used to obtain an ECG, from which R-wave characteristics are selected to trigger a short RF pulse. Pulses carrying heart rate information are interrupted periodically by a series of pulse interval modulated RF pulses conveying temperature information sensed at desired locations by thermistors. Pulse duration and pulse sequencing are used to discriminate between heart rate and temperature pulses as well as radio frequency interference. The implanted transmitter may be used alone for medium and short-range tracking, or with a receiver-transmitter collar that employs commercial tracking equipment for transmissions of up to 12 km. A system prototype has been tested on a dog.

  17. SUMMER STREAM TEMPERATURES, JUVENILE COHO CONDITION FACTORS AND BLACK SPOT INFECTION IN THE OREGON COAST RANGE

    EPA Science Inventory

    We monitored stream temperatures at 35 locations throughout the West Fork Smith River watershed in the Oregon Coast Range during the summer of 2002. Between July 24 and August 24, maximum seven-day moving average high daily temperatures ranged from 21.8 C near the catchment's mo...

  18. Au-Ge film thermometers for temperature range 30 mK-300 K

    NASA Astrophysics Data System (ADS)

    Béthoux, O.; Brusetti, R.; Lasjaunias, J. C.; Sahling, S.

    After optmization of the Au concentration and the annealing temperature, highly sensitive Au-Ge film thermometers for the temperature range 30 mK-300 K were obtained. The thermometers show good reproducibility, a very short relaxation time constant at low temperatures and are quite insensitive to magnetic field.

  19. Temperature-driven range expansion of an irruptive insect heightened by weakly coevolved plant defenses.

    PubMed

    Raffa, Kenneth F; Powell, Erinn N; Townsend, Philip A

    2013-02-01

    Warming climate has increased access of native bark beetles to high-elevation pines that historically received only intermittent exposure to these tree-killing herbivores. Here we show that a dominant, relatively naïve, high-elevation species, whitebark pine, has inferior defenses against mountain pine beetle compared with its historical lower-elevation host, lodgepole pine. Lodgepole pines respond by exuding more resin and accumulating higher concentrations of toxic monoterpenes than whitebark pine, where they co-occur. Furthermore, the chemical composition of whitebark pine appears less able to inhibit the pheromonal communication beetles use to jointly overcome tree defenses. Despite whitebark pine's inferior defenses, beetles were more likely to attack their historical host in mixed stands. This finding suggests there has been insufficient sustained contact for beetles to alter their complex behavioral mechanisms driving host preference. In no-choice assays, however, beetles readily entered and tunneled in both hosts equally, and in stands containing less lodgepole pine, attacks on whitebark pines increased. High-elevation trees in pure stands may thus be particularly vulnerable to temperature-driven range expansions. Predators and competitors were more attracted to volatiles from herbivores attacking their historical host, further increasing risk in less coevolved systems. Our results suggest cold temperatures provided a sufficient barrier against herbivores for high-elevation trees to allocate resources to other physiological processes besides defense. Changing climate may reduce the viability of that evolutionary strategy, and the life histories of high-elevation trees seem unlikely to foster rapid counter adaptation. Consequences extend from reduced food supplies for endangered grizzly bears to altered landscape and hydrological processes.

  20. Performance of Wide Operating Temperature Range Electrolytes in Quallion Prototype Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Tomcsi, M. R.; Nagata, M.; Visco, V.; Tsukamoto, H.

    2010-01-01

    For a number of applications, there is a continued interest in the development of rechargeable lithium-based batteries that can effectively operate over a wide temperature range (i.e., -40 to +70 deg C). These applications include powering future planetary rovers for NASA, enabling the next generation of automotive batteries for DOE, and supporting many DOD applications. Li-ion technology has been demonstrated to have good performance over a reasonably wide temperature range with many systems; however, there is still a desire to improve the low temperature rate capacity as well as the high temperature resilience. In the current study, we would like to present recent results obtained with prototype Li-Ion cells (manufactured by Quallion, LLC) which include various wide operating temperature range electrolytes developed by both JPL and Quallion. To demonstrate the viability of the technology, a number of performance tests were carried out, including: (a) discharge rate characterization over a wide temperature range (down to -60 deg C) using various rates (up to 20C rates), (b) discharge rate characterization at low temperatures with low temperature charging, (c) variable temperature cycling over a wide temperature range (-40 to +70 deg C), and (d) cycling at high temperature (50 deg C). As will be discussed, impressive rate capability was observed at low temperatures with many systems, as well as good resilience to high temperature cycling. To augment the performance testing on the prototype cells, a number of experimental three electrodes cells were fabricated (including Li reference electrodes) to allow the determination of the lithium kinetics of the respective electrodes and interfacial properties as a function of temperatures.

  1. Natural variation in tocochromanols content in Arabidopsis thaliana accessions - the effect of temperature and light intensity.

    PubMed

    Gabruk, Michał; Habina, Iwona; Kruk, Jerzy; Dłużewska, Jolanta; Szymańska, Renata

    2016-06-01

    In this study, 25 accessions of Arabidopsis thaliana originating from a variety of climate conditions were grown under controlled circumstances of different light intensity and temperature. The accessions were analyzed for prenyllipids content and composition, as well as expression of the genes involved in tocochromanol biosynthesis (vte1-5). It was found that the applied conditions did not strongly affect total tocochromanols content and there was no apparent correlation of the tocochromanol content with the origin of the accessions. However, the presented results indicate that the temperature, more than the light intensity, affects the expression of the vte1-5 genes and the content of some prenyllipids. An interesting observation was that under low growth temperature, the hydroxy-plastochromanol (PC-OH) to plastochromanol (PC) ratio was considerably increased regardless of the light intensity in most of the accessions. PC-OH is known to be formed as a result of singlet oxygen stress, therefore this observation indicates that the singlet oxygen production is enhanced under low temperature. Unexpectedly, the highest increase in the PC-OH/PC ratio was found for accessions originating from cold climate (Shigu, Krazo-1 and Lov-5), even though such plants could be expected to be more resistant to low temperature stress.

  2. Wide-Range Temperature Sensors with High-Level Pulse Train Output

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad; Patterson, Richard L.

    2009-01-01

    Two types of temperature sensors have been developed for wide-range temperature applications. The two sensors measure temperature in the range of -190 to +200 C and utilize a thin-film platinum RTD (resistance temperature detector) as the temperature-sensing element. Other parts used in the fabrication of these sensors include NPO (negative-positive- zero) type ceramic capacitors for timing, thermally-stable film or wirewound resistors, and high-temperature circuit boards and solder. The first type of temperature sensor is a relaxation oscillator circuit using an SOI (silicon-on-insulator) operational amplifier as a comparator. The output is a pulse train with a period that is roughly proportional to the temperature being measured. The voltage level of the pulse train is high-level, for example 10 V. The high-level output makes the sensor less sensitive to noise or electromagnetic interference. The output can be read by a frequency or period meter and then converted into a temperature reading. The second type of temperature sensor is made up of various types of multivibrator circuits using an SOI type 555 timer and the passive components mentioned above. Three configurations have been developed that were based on the technique of charging and discharging a capacitor through a resistive element to create a train of pulses governed by the capacitor-resistor time constant. Both types of sensors, which operated successfully over the wide temperature range, have potential use in extreme temperature environments including jet engines and space exploration missions.

  3. 'Optimal thermal range' in ectotherms: Defining criteria for tests of the temperature-size-rule.

    PubMed

    Walczyńska, Aleksandra; Kiełbasa, Anna; Sobczyk, Mateusz

    2016-08-01

    Thermal performance curves for population growth rate r (a measure of fitness) were estimated over a wide range of temperature for three species: Coleps hirtus (Protista), Lecane inermis (Rotifera) and Aeolosoma hemprichi (Oligochaeta). We measured individual body size and examined if predictions for the temperature-size rule (TSR) were valid for different temperatures. All three organisms investigated follow the TSR, but only over a specific range between minimal and optimal temperatures, while maintenance at temperatures beyond this range showed the opposite pattern in these taxa. We consider minimal and optimal temperatures to be species-specific, and moreover delineate a physiological range outside of which an ectotherm is constrained against displaying size plasticity in response to temperature. This thermal range concept has important implications for general size-temperature studies. Furthermore, the concept of 'operating thermal conditions' may provide a new approach to (i) defining criteria required for investigating and interpreting temperature effects, and (ii) providing a novel interpretation for many cases in which species do not conform to the TSR. PMID:27503715

  4. Low-Temperature Blackbodies for Temperature Range from -60 °C to 90 °C

    NASA Astrophysics Data System (ADS)

    Morozova, S. P.; Lisyanskiy, B. E.; Stakharny, A. A.; Samoilov, M. L.; Ogarev, S. A.; Yoo, Yong Shim; Park, Chul-Woung; Park, Seung-Nam

    2011-12-01

    Low-temperature cavity-type blackbodies (BB), VTBB and BB100K1, are developed at VNIIOFI for operation as IR radiation sources of the Middle Background Calibration Facility in the temperature range from -60 °C to 90 °C, which is being constructed by KRISS for calibration of multi-spectral cameras for space applications. The VTBB model, featured by a 30 mm output aperture and hermetic housing and flange for mounting to a vacuum chamber, covers the complete temperature range under a vacuum environment (up to 10-2 Pa), and the temperature range from 20 °C to 90 °C under open air conditions. BB100K1 has a wide aperture of 100 mm diameter, which shows stable operation in the temperature range from -60 °C to 90 °C inside a vacuum chamber, and in the temperature range from -40 °C to 90 °C in a dry-air or inert-gas environment with the usage of an extra hood with an aperture. The effective emissivity of the radiating cavities of both BB, covered with Lord Aeroglaze Z306 black paint, was calculated with the usage of STEEP3 Monte-Carlo simulation software, taking the measured temperature gradients into account. The numerical calculations yield an emissivity of at least 0.9997 for the VTBB cavity, and 0.997 for the BB100K1 cavity. The radiating cavity temperature of VTBB and BB100K1 is stabilized at the level of ±0.01 °C by means of an external precise closed-loop liquid thermostat (Huber Unistat 705 model). The temperature distribution along the radiating cavities and across the BB bottoms is monitored by five precision PRT thermometers and a digital multimeter equipped with a scanner card. Experimental tests using a thermal camera at KRISS demonstrated high-temperature uniformity of both radiation sources not exceeding ±50 mK over the entire temperature range, in vacuum as in a dry-air environment. The combined standard uncertainty of VTBB and BB100K1 temperature measurements accounts for about 40 mK within the range of their working temperatures.

  5. The solubility of hydrogen in plutonium in the temperature range 475 to 825 degrees centigrade

    SciTech Connect

    Allen, T.H.

    1991-01-01

    The solubility of hydrogen (H) in plutonium metal (Pu) was measured in the temperature range of 475 to 825{degree}C for unalloyed Pu (UA) and in the temperature range of 475 to 625{degree}C for Pu containing two-weight-percent gallium (TWP). For TWP metal, in the temperature range 475 to 600{degree}C, the saturated solution has a maximum hydrogen to plutonium ration (H/Pu) of 0.00998 and the standard enthalpy of formation ({Delta}H{degree}{sub f(s)}) is (-0.128 {plus minus} 0.0123) kcal/mol. The phase boundary of the solid solution in equilibrium with plutonium dihydride (PuH{sub 2}) is temperature independent. In the temperature range 475 to 625{degree}C, UA metal has a maximum solubility at H/Pu = 0.011. The phase boundary between the solid solution region and the metal+PuH{sub 2} two-phase region is temperature dependent. The solubility of hydrogen in UA metal was also measured in the temperature range 650 to 825{degree}C with {Delta}H{degree}{sub f(s)} = (-0.104 {plus minus} 0.0143) kcal/mol and {Delta}S{degree}{sub f(s)} = 0. The phase boundary is temperature dependent and the maximum hydrogen solubility has H/Pu = 0.0674 at 825{degree}C. 52 refs., 28 figs., 9 tabs.

  6. Soil moisture sensing with aircraft observations of the diurnal range of surface temperature

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Blanchard, B.; Anderson, A.; Wang, V.

    1977-01-01

    Aircraft observations of the surface temperature were made by measurements of the thermal emission in the 8-14 micrometers band over agricultural fields around Phoenix, Arizona. The diurnal range of these surface temperature measurements were well correlated with the ground measurement of soil moisture in the 0-2 cm layer. The surface temperature observations for vegetated fields were found to be within 1 or 2 C of the ambient air temperature indicating no moisture stress. These results indicate that for clear atmospheric conditions remotely sensed surface temperatures are a reliable indicator of soil moisture conditions and crop status.

  7. Temperature Dependence of Thin Film Spiral Inductors on Alumina Over a Temperature Range of 25 to 475 C

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Jordan, Jennifer L.; Scardelletti, Maximilian C.

    2010-01-01

    In this paper, we present an analysis of inductors on an Alumina substrate over the temperature range of 25 to 475 C. Five sets of inductors, each set consisting of a 1.5, 2.5, 3.5, and a 4.5 turn inductor with different line width and spacing, were measured on a high temperature probe station from 10 MHz to 30 GHz. From these measured characteristics, it is shown that the inductance is nearly independent of temperature for low frequencies compared to the self resonant frequency, the parasitic capacitances are independent of temperature, and the resistance varies nearly linearly with temperature. These characteristics result in the self resonant frequency decreasing by only a few percent as the temperature is increased from 25 to 475 C, but the maximum quality factor decreases by a factor of 2 to 3. These observations based on measured data are confirmed through 2D simulations using Sonnet software.

  8. Reaction rate constants of HO2 + O3 in the temperature range 233-400 K

    NASA Technical Reports Server (NTRS)

    Wang, Xiuyan; Suto, Masako; Lee, L. C.

    1988-01-01

    The reaction rate constants of HO2 + O3 were measured in the temperature range 233-400 K using a discharge flow system with photofragment emission detection. In the range 233-253 K, the constants are approximately a constant value, and then increase with increasing temperature. This result suggests that the reaction may have two different channels. An expression representing the reaction rate constants is presented.

  9. Effect of growth temperature on glucosinolate profiles in Arabidopsis thaliana accessions.

    PubMed

    Kissen, Ralph; Eberl, Franziska; Winge, Per; Uleberg, Eivind; Martinussen, Inger; Bones, Atle M

    2016-10-01

    Glucosinolates are plant secondary metabolites with important roles in plant defence against pathogens and pests and are also known for their health benefits. Understanding how environmental factors affect the level and composition of glucosinolates is therefore of importance in the perspective of climate change. In this study we analysed glucosinolates in Arabidopsis thaliana accessions when grown at constant standard (21 °C), moderate (15 °C) and low (9 °C) temperatures during three generations. In most of the tested accessions moderate and pronounced chilling temperatures led to higher levels of glucosinolates, especially aliphatic glucosinolates. Which temperature yielded the highest glucosinolate levels was accession-dependent. Transcriptional profiling revealed also accession-specific gene responses, but only a limited correlation between changes in glucosinolate-related gene expression and glucosinolate levels. Different growth temperatures in one generation did not consistently affect glucosinolate composition in subsequent generations, hence a clear transgenerational effect of temperature on glucosinolates was not observed. PMID:27319377

  10. Diurnal temperature range compression hastens berry development and modifies flavonoid partitioning in grapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Temperatures during the day and night are known to influence grape berry metabolism and resulting composition. In this study, the flavonoid composition of field-grown Vitis vinifera L. cv. Merlot berries was investigated as a function of diurnal temperature range (DTR). The DTR was compressed by c...

  11. Seasonal variability of diurnal temperature range in Egypt with links to atmospheric circulations and sea surface temperature

    NASA Astrophysics Data System (ADS)

    El Kenawy, A.; Lopez Moreno, J. I.; Vicente-Serrano, S.

    2010-09-01

    The diurnal temperature range (DTR) is an important climate-change variable. Seasonal and annual variability of DTR in Egypt was investigated based on a monthly dataset of 40 observatories distributing across the country. The trends were calculated using the Rho spearman rank test at the 95 % level of significance. The trends at the independent individual scale were compared with a regional series created for the whole country following the Thiessen polygon approach. A cross-tabulation analysis was performed between the trends of the DTR and the trends of maximum and minimum temperatures to account for directional causes of variability of the DTR at seasonal and annual scales. The physical processes controlling the DTR variability were also assessed in terms of large atmospheric circulations representing in the indices of the North Atlantic Oscillation (NAO), the East Atlantic (EA) pattern, El Niño Southern Oscillation (ENSO) index and the EAWR (East Atlantic/West Russia) Pattern. Also, the variability of the DTR was linked with anomaly of Sea Surface Temperature (SST). A cooling trend was observed in Egypt with strong behavior in winter and summer rather than fall and spring. The upwarding trend of the mean minimum temperature was mainly responsible for variability of the DTR rather than the mean maximum temperature. Also, the EA and the EAWR indices were the main indices accounted for most of variation in the DTR in Egypt, particularly in summer. Key words: trend analysis, temperature variability, Diurnal temperature range, atmospheric circulation, sea surface temperature, Egypt.

  12. Serial temperature monitoring and comparison of rectal and muscle temperatures in immobilized free-ranging black rhinoceros (Diceros bicornis).

    PubMed

    vdB Morkel, Peter; Miller, Michele; Jago, Mark; Radcliffe, Robin W; du Preez, Pierre; Olea-Popelka, Francisco; Sefton, Jennifer; Taft, Arthur; Nydam, Daryl; Gleed, Robin D

    2012-03-01

    Control of body temperature is critical to a successful anesthetic outcome, particularly during field immobilization of wild animals. Hyperthermia associated with exertion can lead to serious and potentially life-threatening complications such as organ damage (including myopathy) and death. Methods for monitoring core body temperature must accurately reflect the physiologic status of the animal in order for interventions to be effective. The goal of this preliminary study was to compare serial rectal and muscle temperatures in field-immobilized black rhinoceros (Diceros bicornis) and evaluate a possible association. Twenty-four free-ranging black rhinoceros were immobilized between February and March of 2010 in Ethosha National Park, Namibia. Pairwise comparisons showed a correlation of 0.73 (95% CI; 0.70-0.75) between rectal and muscle temperature measurements. Results from a multivariable model indicate that muscle temperature readings were, on average, 0.46 degrees C (95% CI; 0.36-0.57 degrees C) higher than rectal temperatures while adjusting for repeated measurements on the same rhinoceros, effect of duration of immobilization, and effect of ambient temperature on rhinoceroses' temperature readings. As immobilization time increased, muscle and rectal temperature values within an individual rhinoceros tended to equilibrate. The overall temperatures decreased by an average of 0.00059 degrees C/min (95% CI; -0.0047 to -0.0035 degrees C/min; P = 0.779). As the ambient temperature at time of immobilization increased by 1 degree C, the average rhinoceros temperature increased by 0.09 degrees C (95% CI; 0.06-0.11 degrees C, P < 0.0001). Higher body temperature creates a potential for cellular damage leading to complications that include myopathy. Methods for monitoring rectal, muscle, and ambient temperatures should be incorporated into anesthetic monitoring protocols for large ungulates, particularly under field conditions.

  13. Cell separator operation within temperature ranges to minimize effects on Chinese hamster ovary cell perfusion culture.

    PubMed

    Drouin, Hans; Ritter, Joachim B; Gorenflo, Volker M; Bowen, Bruce D; Piret, James M

    2007-01-01

    A cell retention device that provides reliable high-separation efficiency with minimal negative effects on the cell culture is essential for robust perfusion culture processes. External separation devices generally expose cells to periodic variations in temperature, most commonly temperatures below 37 degrees C, while the cells are outside the bioreactor. To examine this phenomenon, aliquots of approximately 5% of a CHO cell culture were exposed to 60 s cyclic variations of temperature simulating an acoustic separator environment. It was found that, for average exposure temperatures between 31.5 and 38.5 degrees C, there were no significant impacts on the rates of growth, glucose consumption, or t-PA production, defining an acceptable range of operating temperatures. These results were subsequently confirmed in perfusion culture experiments for average exposure temperatures between 31.6 and 38.1 degrees C. A 2(5-1) central composite factorial design experiment was then performed to systematically evaluate the effects of different operating variables on the inlet and outlet temperatures of a 10L acoustic separator. The power input, ambient temperature, as well as the perfusion and recycle flow rates significantly influenced the temperature, while the cell concentration did not. An empirical model was developed that predicted the temperature changes between the inlet and the outlet of the acoustic separator within +/-0.5 degrees C. A series of perfusion experiments determined the ranges of the significant operational settings that maintained the acoustic separator inlet and outlet temperatures within the acceptable range. For example, these objectives were always met by using the manufacturer-recommended operational settings as long as the recirculation flow rate was maintained above 15 L day(-1) and the ambient temperature was near 22 degrees C.

  14. Sensitivity, range and temperature dependence of hearing in the grass frog and fire-bellied toad.

    PubMed

    Walkowiak, W

    1980-12-01

    Multi-unit recordings from the torus semicircularis of the fire-bellied toad (Bombina bombina L.) and the grass frog (Rana t. temporaria L.) were used to obtain threshold vs. frequency curves for these anurans. The effect of body temperature on these audiograms was tested over a range of 10-28° C for the toad and 5-20° C for the frog. The range of frequencies audible to the fire-bellied toad at a body temperature of 21° C extends to 2400-3000 Hz. Threshold is relatively low in three regions: 300-450 Hz, 700-900 Hz and 1200-1700 Hz. The auditory system is most sensitive in the low frequency region. The audiograms of both species depend greatly on temperature. As temperature is increased sensitivity is enhanced, particularly at low and intermediate frequencies. Grass frogs are maximally sensitive at temperatures as low as 15° C, whereas the auditory threshold of fire-bellied toads continue to fall as the temperature is raised from 16° C to 22° C. Hearing evidently is adapted to different temperature ranges in the two species, and these correspond to the temperatures at which the animals engage in mating behavior.

  15. Electrolytes for Use in High Energy Lithium-Ion Batteries with Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2011-01-01

    Objectives of this work are: (1) Develop advanced Li -ion electrolytes that enable cell operation over a wide temperature range (i.e., -30 to +60C). (2) Improve the high temperature stability and lifetime characteristics of wide operating temperature electrolytes. (3) Improve the high voltage stability of these candidate electrolytes systems to enable operation up to 5V with high specific energy cathode materials. (4) Define the performance limitations at low and high temperature extremes, as well as, life limiting processes. (5) Demonstrate the performance of advanced electrolytes in large capacity prototype cells.

  16. Infrared thermal imaging as a physiological access pathway: a study of the baseline characteristics of facial skin temperatures.

    PubMed

    Nhan, B R; Chau, T

    2009-04-01

    In this study we examine the baseline characteristics of facial skin temperature, as measured by dynamic infrared thermal imaging, to gauge its potential as a physiological access pathway for non-verbal individuals with severe motor impairments. Frontal facial recordings were obtained from 12 asymptomatic adults in a resting state with a high-end infrared thermal imaging system. From the infrared thermal recordings, mean skin temperature time series were generated for regions of interest encompassing the nasal, periorbital and supraorbital areas. A 90% bandwidth for all regions of interest was found to be in the 1 Hz range. Over 70% of the time series were identified as nonstationary (p<0.05), with the nonstationary mean as the greatest contributing source. Correlation coefficients between regions were significant (p<0.05) and ranged from values of 0.30 (between periorbital and supraorbital regions) to 0.75 (between contralateral supraorbital regions). Using information measures, we concluded that the greatest degree of information existed in the nasal and periorbital regions. Mutual information existed across all regions but was especially prominent between the nasal and periorbital regions. Results from this study provide insight into appropriate analysis methods and potential discriminating features for the application of facial skin temperature as a physiological access pathway. PMID:19332894

  17. High temperature adhesive silicone foam composition, foam generating system and method of generating foam. [For access denial

    DOEpatents

    Mead, J.W.; Montoya, O.J.; Rand, P.B.; Willan, V.O.

    1983-12-21

    Access to a space is impeded by generation of a sticky foam from a silicone polymer and a low boiling solvent such as a halogenated hydrocarbon. In a preferred aspect, the formulation is polydimethylsiloxane gel mixed with F502 Freon as a solvent and blowing agent, and pressurized with CO/sub 2/ in a vessel to about 250 PSI, whereby when the vessel is opened, a sticky and solvent resistant foam is deployed. The foam is deployable, over a wide range of temperatures, adhering to wet surfaces as well as dry, is stable over long periods of time and does not propagate flame or lose adhesive properties during an externally supported burn.

  18. Measurement of effective temperature range of fire service thermal imaging cameras

    NASA Astrophysics Data System (ADS)

    Amon, Francine; Bryner, Nelson

    2008-04-01

    The use of thermal imaging cameras (TIC) by the fire service is increasing as fire fighters become more aware of the value of these tools. The National Fire Protection Association (NFPA) is currently developing a consensus standard for design and performance requirements of TIC as used by the fire service. The National Institute of Standards and Technology facilitates this process by providing recommendations for science-based performance metrics and test methods to the NFPA technical committee charged with the development of this standard. A suite of imaging performance metrics and test methods, based on the harsh operating environment and limitations of use particular to the fire service, has been proposed for inclusion in the standard. The Effective Temperature Range (ETR) measures the range of temperatures that a TIC can view while still providing useful information to the user. Specifically, extreme heat in the field of view tends to inhibit a TIC's ability to discern surfaces having intermediate temperatures, such as victims and fire fighters. The ETR measures the contrast of a target having alternating 25 °C and 30 °C bars while an increasing temperature range is imposed on other surfaces in the field of view. The ETR also indicates the thermal conditions that trigger a shift in integration time common to TIC employing microbolometer sensors. The reported values for this imaging performance metric are the hot surface temperature range within which the TIC provides adequate bar contrast, and the hot surface temperature at which the TIC shifts integration time.

  19. HTP kinetics studies on isolated elementary combustion reactions over wide temperature ranges

    SciTech Connect

    Fontijn, A.; Adusei, G.Y.; Hranisavlevic, J.; Bajaj, P.N.

    1993-12-01

    The goals of this project are to provide accurate data on the temperature dependence of the kinetics of elementary combustion reactions, (i) for use by combustion modelers, and (ii) to gain a better fundamental understanding of, and hence predictive ability for, the chemistry involved. Experimental measurements are made mainly by using the pseudo-static HTP (high-temperature photochemistry) technique. While continuing rate coefficient measurements, further aspects of kinetics research are being explored. Thus, starting from the data obtained, a method for predicting the temperature dependence of rate coefficients of oxygen-atom olefin experiment and confirms the underlying mechanistic assumptions. Mechanistic information of another sort, i.e. by product analysis, has recently become accessible with the inauguration of our heated flow tube mass spectrometer facility; early results are reported here. HTP experiments designed to lead to measurements of product channels by resonance fluorescence have started.

  20. Increasing sea surface temperature and range shifts of intertidal gastropods along the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Rubal, Marcos; Veiga, Puri; Cacabelos, Eva; Moreira, Juan; Sousa-Pinto, Isabel

    2013-03-01

    There are well-documented changes in abundance and geographical range of intertidal invertebrates related to climate change at north Europe. However, the effect of sea surface warming on intertidal invertebrates has been poorly studied at lower latitudes. Here we analyze potential changes in the abundance patterns and distribution range of rocky intertidal gastropods related to climate change along the Iberian Peninsula. To achieve this aim, the spatial distribution and range of sub-tropical, warm- and cold-water species of intertidal gastropods was explored by a fully hierarchical sampling design considering four different spatial scales, i.e. from region (100 s of km apart) to quadrats (ms apart). Variability on their patterns of abundance was explored by analysis of variance, changes on their distribution ranges were detected by comparing with previous records and their relationship with sea water temperature was explored by rank correlation analyses. Mean values of sea surface temperature along the Iberian coast, between 1949 and 2010, were obtained from in situ data compiled for three different grid squares: south Portugal, north Portugal, and Galicia. Lusitanian species did not show significant correlation with sea water temperature or changes on their distributional range or abundance, along the temperature gradient considered. The sub-tropical species Siphonaria pectinata has, however, increased its distribution range while boreal cold-water species showed the opposite pattern. The latter was more evident for Littorina littorea that was almost absent from the studied rocky shores of the Iberian Peninsula. Sub-tropical and boreal species showed significant but opposite correlation with sea water temperature. We hypothesized that the energetic cost of frequent exposures to sub-lethal temperatures might be responsible for these shifts. Therefore, intertidal gastropods at the Atlantic Iberian Peninsula coast are responding to the effect of global warming as it

  1. Structural properties of fluids with short-range attractive and repulsive tails: Inverse temperature expansion

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Young; Kim, Soon-Chul

    2014-03-01

    Thermodynamic perturbation theories based on a power series in the inverse temperature have been proposed for studying the structure of square-well and square-shoulder fluids in various ranges, and the results have compared with those from computer simulations. The perturbation theory based on the hard-sphere reference system seems to reproduce the simulation data at high temperature. However, it fails in the region of low density and low temperature. On the other hand, the perturbation theory based on the high-temperature reference system, which incorporates both repulsive and short-range attractive/repulsive tails is in excellent agreement with simulation results and is more accurate than the perturbation theory based on the hard-sphere reference system. In particular, the perturbation theory based on the high-temperature reference system is the most successful for a square-shoulder fluid with a purely repulsive potential and is more accurate than the rational function approximation of Yuste et al. [Mol. Phys. 109 987 (2011)] for the whole density range. In this case, the convergence of the power series in the inverse temperature is seen to be quiet satisfactory even for low density and low temperature.

  2. Ultrawideband temperature-dependent dielectric properties of animal liver tissue in the microwave frequency range.

    PubMed

    Lazebnik, Mariya; Converse, Mark C; Booske, John H; Hagness, Susan C

    2006-04-01

    The development of ultrawideband (UWB) microwave diagnostic and therapeutic technologies, such as UWB microwave breast cancer detection and hyperthermia treatment, is facilitated by accurate knowledge of the temperature- and frequency-dependent dielectric properties of biological tissues. To this end, we characterize the temperature-dependent dielectric properties of a representative tissue type-animal liver-from 0.5 to 20 GHz. Since discrete-frequency linear temperature coefficients are impractical and inappropriate for applications spanning wide frequency and temperature ranges, we propose a novel and compact data representation technique. A single-pole Cole-Cole model is used to fit the dielectric properties data as a function of frequency, and a second-order polynomial is used to fit the Cole-Cole parameters as a function of temperature. This approach permits rapid estimation of tissue dielectric properties at any temperature and frequency.

  3. Analysis of the Dryden Wet Bulb GLobe Temperature Algorithm for White Sands Missile Range

    NASA Technical Reports Server (NTRS)

    LaQuay, Ryan Matthew

    2011-01-01

    In locations where workforce is exposed to high relative humidity and light winds, heat stress is a significant concern. Such is the case at the White Sands Missile Range in New Mexico. Heat stress is depicted by the wet bulb globe temperature, which is the official measurement used by the American Conference of Governmental Industrial Hygienists. The wet bulb globe temperature is measured by an instrument which was designed to be portable and needing routine maintenance. As an alternative form for measuring the wet bulb globe temperature, algorithms have been created to calculate the wet bulb globe temperature from basic meteorological observations. The algorithms are location dependent; therefore a specific algorithm is usually not suitable for multiple locations. Due to climatology similarities, the algorithm developed for use at the Dryden Flight Research Center was applied to data from the White Sands Missile Range. A study was performed that compared a wet bulb globe instrument to data from two Surface Atmospheric Measurement Systems that was applied to the Dryden wet bulb globe temperature algorithm. The period of study was from June to September of2009, with focus being applied from 0900 to 1800, local time. Analysis showed that the algorithm worked well, with a few exceptions. The algorithm becomes less accurate to the measurement when the dew point temperature is over 10 Celsius. Cloud cover also has a significant effect on the measured wet bulb globe temperature. The algorithm does not show red and black heat stress flags well due to shorter time scales of such events. The results of this study show that it is plausible that the Dryden Flight Research wet bulb globe temperature algorithm is compatible with the White Sands Missile Range, except for when there are increased dew point temperatures and cloud cover or precipitation. During such occasions, the wet bulb globe temperature instrument would be the preferred method of measurement. Out of the 30

  4. Electrolytes for Use in High Energy Lithium-ion Batteries with Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2012-01-01

    Met programmatic milestones for program. Demonstrated improved performance with wide operating temperature electrolytes containing ester co-solvents (i.e., methyl butyrate) containing electrolyte additives in A123 prototype cells: Previously demonstrated excellent low temperature performance, including 11C rates at -30 C and the ability to perform well down to -60 C. Excellent cycle life at room temperature has been displayed, with over 5,000 cycles being demonstrated. Good high temperature cycle life performance has also been achieved. Demonstrated improved performance with methyl propionate-containing electrolytes in large capacity prototype cells: Demonstrated the wide operating temperature range capability in large cells (12 Ah), successfully scaling up technology from 0.25 Ah size cells. Demonstrated improved performance at low temperature and good cycle life at 40 C with methyl propionate-based electrolyte containing increasing FEC content and the use of LiBOB as an additive. Utilized three-electrode cells to investigate the electrochemical characteristics of high voltage systems coupled with wide operating temperature range electrolytes: From Tafel polarization measurements on each electrode, it is evident the NMC-based cathode displays poor lithium kinetics (being the limiting electrode). The MB-based formulations containing LiBOB delivered the best rate capability at low temperature, which is attributed to improved cathode kinetics. Whereas, the use of lithium oxalate as an additive lead to the highest reversible capacity and lower irreversible losses.

  5. Broadening of mesophase temperature range induced by doping calamitic mesogen with banana-shaped mesogen

    NASA Astrophysics Data System (ADS)

    Cvetinov, Miroslav; Stojanović, Maja; Obadović, Dušanka; Vajda, Aniko; Fodor-Csorba, Katalin; Eber, Nandor

    2016-03-01

    We have investigated three binary mixtures composed of selected banana-shaped dopant in low concentrations and calamitic mesogen in high. Banana-shaped dopant forms a B7 phase, while the calamitic mesogen exhibit nematic and smectic SmA and SmC phases. The occurring mesophases have been identified by their optical textures. At dopant concentrations of 2.2 and 3.1 mol%, there is evident broadening of nematic and smectic SmA temperature ranges in respect to the pure calamitic compound. Yet, the mixture with dopant concentration of 7 mol% exhibits narrower temperature ranges of mesophases. Increasing dopant concentration caused lowering of all phase transitions temperatures (TI-N, TN-SmA, TSmA-SmC) in all investigated mixtures. Therefore, mixing classic calamitic compounds with novel banana-shaped compound in low concentrations is viable way to attain useful mesophase range for application in industry.

  6. Astable Oscillator Circuits using Silicon-on-Insulator Timer Chip for Wide Range Temperature Sensing

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Culley, Dennis; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Two astable oscillator circuits were constructed using a new silicon-on-insulator (SOI) 555 timer chip for potential use as a temperature sensor in harsh environments encompassing jet engine and space mission applications. The two circuits, which differed slightly in configuration, were evaluated between -190 and 200 C. The output of each circuit was made to produce a stream of rectangular pulses whose frequency was proportional to the sensed temperature. The preliminary results indicated that both circuits performed relatively well over the entire test temperature range. In addition, after the circuits were subjected to limited thermal cycling over the temperature range of -190 to 200 C, the performance of either circuit did not experience any significant change.

  7. Development of ice slurry for cold storage of foods in wide temperature range

    NASA Astrophysics Data System (ADS)

    Matsumoto, Koji; Kaneko, Atsushi; Teraoka, Yoshikazu; Igarashi, Yoshito

    In order to popularize use of ice slurry, authors have been proposed application of ice slurry to cold storage of foods in place of an air conditioning. For use of the ice slurry in the wide temperature range a new harmless ice slurry to human being was developed by cooling a W/O emulsion made from tap water-edible oil mixture with small amounts of edible emulsifier and food additive. The edible emulsifier is essential to form W/O emulsion, and the food additive is used to dissolve in tap water. In this paper the optimal concentrations of emulsifiers were determined, and the fundamental characteristics such as viscosity, effective latent heat of fusion and usable temperature of ice slurry were clarified. Finally, it was concluded that new ice slurry could be fully applied to cold storage of foods in the wide temperature range because its lower limit usable temperature was about -18°C.

  8. On-road evaluation of advanced hybrid electric vehicles over a wide range of ambient temperatures.

    SciTech Connect

    Carlson, R.; Duoba, M. J.; Bocci, D.; Lohse-Busch, H.

    2007-01-01

    In recent years, Hybrid Electric Vehicles (HEV's) have become a production viable and effective mode of efficient transportation. HEV's can provide increased fuel economy over convention technology vehicle, but these advantages can be affected dramatically by wide variations in operating temperatures. The majority of data measured for benchmarking HEV technologies is generated from ambient test cell temperatures at 22 C. To investigate cold and hot temperature affects on HEV operation and efficiency, an on-road evaluation protocol is defined and conducted over a six month study at widely varying temperatures. Two test vehicles, the 2007 Toyota Camry HEV and 2005 Ford Escape HEV, were driven on a pre-defined urban driving route in ambient temperatures ranging from -14 C to 31 C. Results from the on-road evaluation were also compared and correlated to dynamometer testing of the same drive cycle. Results from this on-road evaluation show the battery power control limits and engine operation dramatically change with temperature. These changes decrease fuel economy by more than two times at -14 C as compared to 25 C. The two vehicles control battery temperature in different manners. The Escape HEV uses the air conditioning system to provide cool air to the batteries at high temperatures and is therefore able to maintain battery temperature to less than 33 C. The Camry HEV uses cabin air to cool the batteries. The observed maximum battery temperature was 44 C.

  9. Effects of body size and home range on access to mates and paternity in male bridled nailtail wallabies.

    PubMed

    Fisher; Lara

    1999-07-01

    The bridled nailtail wallaby, Onychogalea fraenata, is a relatively small, solitary and sexually size dimorphic macropod. We studied the mating system of free-ranging wallabies over 3 years, using microsatellite analysis of paternity, radiotelemetry and behavioural observations. Both sexes were promiscuous, and general reproductive behaviour was similar to that of larger, better-known macropods. Home range size influenced the number of associations with oestrous females, and was a significant component of male reproductive success. Female population density varied within the site, but males with home ranges that overlapped more females did not sire more offspring. Aggression between males occurred only around oestrous females and males did not establish a predetermined dominance hierarchy. Male body weight strongly influenced priority of access to oestrous females, and was related to age. The number of times that males were seen closest to an oestrous female when other males were present (priority of access) was the most important predictor of variation in the number of offspring sired. Females mated with several males within and between oestrous cycles, and may have influenced male-male competition by prolonging advertisement of approaching oestrus, expanding their home ranges at oestrus and engaging in mate chases that attracted groups of up to six males. Despite overall similarities in the mating system of this species and that of other macropods, male mating success may be less skewed in bridled nailtail wallabies than in other species, although paternity analysis of free-ranging populations of other species is required to confirm this conclusion. Copyright 1999 The Association for the Study of Animal Behaviour. PMID:10413548

  10. Thermodynamic properties of boron suboxide in the temperature range 11.44-781.8 K

    NASA Astrophysics Data System (ADS)

    Tsagareishvili, G. V.; Tsagareishvili, D. Sh.; Tushishvili, M. Ch.; Omiadze, I. S.; Naumov, V. N.; Tagaev, A. B.

    1991-07-01

    Heat capacity of boron suboxide (B6O) have been determined in the vacuum adiabatic calorimeter with pulse heat supply in the temperature range 11.44-311.84 K. The values of its low-temperature heat capacity (Cp), entropy (S), enthalpy (Ht-Ho) and reduced thermodynamic potential (-(G-Ho)/T) were tabulated. The values of the enthalpy (Ht-H298.15), average (Cp) and true heat capacities of B6O have been determined by mixing isothermal massive calorimetry. Experimental results were treated by least-squares method. Equations of temperature dependence of thermodynamic characteristics of boron suboxide were obtained. The curve of temperature dependence of its Debye characteristic temperature was plotted.

  11. Electronic Transport of an Ni/ n-GaAs Diode Analysed Over a Wide Temperature Range

    NASA Astrophysics Data System (ADS)

    Guzel, A.; Duman, S.; Yildirim, N.; Turut, A.

    2016-06-01

    We have reported a study on current-voltage ( I-V) characteristics and capacitance-voltage ( C-V) of an Ni/ n-GaAs Schottky barrier diode in a wide temperature ( T) range of 100-320 K in steps of 20 K, which is prepared by a magnetron direct current sputtering technique. The ideality factor decreases and barrier height (BH) increases with an increase in the temperature. The variation of the diode parameters with the sample temperature has been attributed to the presence of the lateral inhomogeneities in the BH. It has been seen that the junction current is dominated by thermionic field emission. The carrier concentration, diffusion potential, BH, Fermi energy level and the temperature coefficient of the BH have been calculated from the temperature-dependent C-V-T characteristics.

  12. Equatorial range limits of an intertidal ectotherm are more linked to water than air temperature.

    PubMed

    Seabra, Rui; Wethey, David S; Santos, António M; Gomes, Filipa; Lima, Fernando P

    2016-10-01

    As climate change is expected to impose increasing thermal stress on intertidal organisms, understanding the mechanisms by which body temperatures translate into major biogeographic patterns is of paramount importance. We exposed individuals of the limpet Patella vulgata Linnaeus, 1758, to realistic experimental treatments aimed at disentangling the contribution of water and air temperature for the buildup of thermal stress. Treatments were designed based on temperature data collected at the microhabitat level, from 15 shores along the Atlantic European coast spanning nearly 20° of latitude. Cardiac activity data indicated that thermal stress levels in P. vulgata are directly linked to elevated water temperature, while high air temperature is only stressful if water temperature is also high. In addition, the analysis of the link between population densities and thermal regimes at the studied locations suggests that the occurrence of elevated water temperature may represent a threshold P. vulgata is unable to tolerate. By combining projected temperatures with the temperature threshold identified, we show that climate change will likely result in the westward expansion of the historical distribution gap in the Bay of Biscay (southwest France), and northward contraction of the southern range limit in south Portugal. These findings suggest that even a minor relaxing of the upwelling off northwest Iberia could lead to a dramatic increase in thermal stress, with major consequences for the structure and functioning of the intertidal communities along Iberian rocky shores.

  13. Equatorial range limits of an intertidal ectotherm are more linked to water than air temperature.

    PubMed

    Seabra, Rui; Wethey, David S; Santos, António M; Gomes, Filipa; Lima, Fernando P

    2016-10-01

    As climate change is expected to impose increasing thermal stress on intertidal organisms, understanding the mechanisms by which body temperatures translate into major biogeographic patterns is of paramount importance. We exposed individuals of the limpet Patella vulgata Linnaeus, 1758, to realistic experimental treatments aimed at disentangling the contribution of water and air temperature for the buildup of thermal stress. Treatments were designed based on temperature data collected at the microhabitat level, from 15 shores along the Atlantic European coast spanning nearly 20° of latitude. Cardiac activity data indicated that thermal stress levels in P. vulgata are directly linked to elevated water temperature, while high air temperature is only stressful if water temperature is also high. In addition, the analysis of the link between population densities and thermal regimes at the studied locations suggests that the occurrence of elevated water temperature may represent a threshold P. vulgata is unable to tolerate. By combining projected temperatures with the temperature threshold identified, we show that climate change will likely result in the westward expansion of the historical distribution gap in the Bay of Biscay (southwest France), and northward contraction of the southern range limit in south Portugal. These findings suggest that even a minor relaxing of the upwelling off northwest Iberia could lead to a dramatic increase in thermal stress, with major consequences for the structure and functioning of the intertidal communities along Iberian rocky shores. PMID:27109165

  14. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    PubMed

    Clements, Hayley S; Tambling, Craig J; Hayward, Matt W; Kerley, Graham I H

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points) with high rates of detection (75% to 100% of simulations, depending on number of break-points) and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point). When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah), 82±3% (leopard), 81±2% (lion), 97±2% (spotted hyaena) and 96±2% (wild dog) of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore species. PMID

  15. An Objective Approach to Determining the Weight Ranges of Prey Preferred by and Accessible to the Five Large African Carnivores

    PubMed Central

    Clements, Hayley S.; Tambling, Craig J.; Hayward, Matt W.; Kerley, Graham I. H.

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points) with high rates of detection (75% to 100% of simulations, depending on number of break-points) and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point). When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed “accessible prey”. Accessible prey weight ranges were found to be 14–135 kg for cheetah Acinonyx jubatus, 1–45 kg for leopard Panthera pardus, 32–632 kg for lion Panthera leo, 15–1600 kg for spotted hyaena Crocuta crocuta and 10–289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah), 82±3% (leopard), 81±2% (lion), 97±2% (spotted hyaena) and 96±2% (wild dog) of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore

  16. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    PubMed

    Clements, Hayley S; Tambling, Craig J; Hayward, Matt W; Kerley, Graham I H

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points) with high rates of detection (75% to 100% of simulations, depending on number of break-points) and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point). When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah), 82±3% (leopard), 81±2% (lion), 97±2% (spotted hyaena) and 96±2% (wild dog) of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore species.

  17. Thermodynamic properties of saturated liquid parahydrogen charted for important temperature range

    NASA Technical Reports Server (NTRS)

    Mc Carty, R. D.; Roder, H. M.

    1967-01-01

    Six entropy diagrams for parahydrogen in or near the saturated liquid state cover the temperature range from 29.16 degrees to 42.48 degrees R with pressures to 100 psia and mixtures of the liquid and vapor phases to 0.003 quality. The diagrams are printed in color, are 19 by 30 inches in size, and are suitable for wall mounting.

  18. Operation of a New COTS Crystal Oscillator - CXOMHT over a Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2011-01-01

    Crystal oscillators are extensively used in electronic circuits to provide timing or clocking signals in data acquisition, communications links, and control systems, to name a few. They are affordable, small in size, and reliable. Because of the inherent characteristics of the crystal, the oscillator usually exhibits extreme accuracy in its output frequency within the intrinsic crystal stability. Stability of the frequency could be affected under varying load levels or other operational conditions. Temperature is one of those important factors that influence the frequency stability of an oscillator; as it does to the functionality of other electronic components. Electronics designed for use in NASA deep space and planetary exploration missions are expected to be exposed to extreme temperatures and thermal cycling over a wide range. Thus, it is important to design and develop circuits that are able to operate efficiently and reliably under in these harsh temperature environments. Most of the commercial-off-the-shelf (COTS) devices are very limited in terms of their specified operational temperature while very few custom-made commercial and military-grade parts have the ability to operate in a slightly wider range of temperature than those of the COTS parts. These parts are usually designed for operation under one temperature extreme, i.e. hot or cold, and do not address the wide swing in the operational temperature, which is typical of the space environment. For safe and successful space missions, electronic systems must therefore be designed not only to withstand the extreme temperature exposure but also to operate efficiently and reliably. This report presents the results obtained on the evaluation of a new COTS crystal oscillator under extreme temperatures.

  19. Electrical Transport Over Wide Temperature Range In Doped And Undoped Polypyrrole

    SciTech Connect

    Taunk, Manish; Chand, Subhash

    2010-12-01

    Polypyrrole was synthesized by chemical oxidation method by varying oxidant to monomer molar ratio for the optimization of electrical conductivity without using any external dopant. The conductivity in doped polypyrrole reached up to a maximum value of 7.2 S/cm. Neutralization of doped polypyrrole was done with aqueous ammonium hydroxide and three orders of reduced conductivity was obtained in neutral polypyrrole. Doping and neutralization of polypyrrole samples was supported by FTIR spectroscopy. Doped and undoped samples of polypyrrole were then electrically characterized over wide temperature range of 10-300 K. Stronger and weak temperature dependence of conductivity was revealed by undoped and doped polypyrrole samples respectively. An effort has been made to explore the electrical transport in doped and undoped polypyrrole by charge transport models. The experimental data obeys Kivelson's hopping model in temperature range of 60-300 K and fluctuation assisted tunneling was dominant conduction mechanism below 80 K.

  20. Variable range hopping conduction in n-CdSe samples at very low temperature

    NASA Astrophysics Data System (ADS)

    Errai, M.; El Kaaouachi, A.; El Idrissi, H.

    2015-12-01

    We reanalyzed experimental data already published in Friedman J R, Zhang Y, Dai P, et al. Phys Rev B, 1996, 53(15): 9528. Variable range hopping (VRH) conduction in the insulating three-dimensional n-CdSe samples has been studied over the entire temperature range from 0.03 to 1 K. In the absence of a magnetic field, the low temperature conductivity σ of the three samples (A, B and C) obeys the Mott VRH conduction with an appropriate temperature dependence in the prefactor (σ = σ0 exp[-(T0/T)]p with p ≈ 0.25). This behavior can be explained by a VRH model where the transport occurs by hopping between localized states in the vicinity of the Fermi level, EF, without creation of the Coulomb gap (CG). On the contrary, no Efros-Shklovskii VRH is observed, suggesting that the density is constant in the vicinity of the EF.

  1. Variation at range margins across multiple spatial scales: environmental temperature, population genetics and metabolomic phenotype

    PubMed Central

    Kunin, William E.; Vergeer, Philippine; Kenta, Tanaka; Davey, Matthew P.; Burke, Terry; Ian Woodward, F.; Quick, Paul; Mannarelli, Maria-Elena; Watson-Haigh, Nathan S.; Butlin, Roger

    2009-01-01

    Range margins are spatially complex, with environmental, genetic and phenotypic variations occurring across a range of spatial scales. We examine variation in temperature, genes and metabolomic profiles within and between populations of the subalpine perennial plant Arabidopsis lyrata ssp. petraea from across its northwest European range. Our surveys cover a gradient of fragmentation from largely continuous populations in Iceland, through more fragmented Scandinavian populations, to increasingly widely scattered populations at the range margin in Scotland, Wales and Ireland. Temperature regimes vary substantially within some populations, but within-population variation represents a larger fraction of genetic and especially metabolomic variances. Both physical distance and temperature differences between sites are found to be associated with genetic profiles, but not metabolomic profiles, and no relationship was found between genetic and metabolomic population structures in any region. Genetic similarity between plants within populations is the highest in the fragmented populations at the range margin, but differentiation across space is the highest there as well, suggesting that regional patterns of genetic diversity may be scale dependent. PMID:19324821

  2. Dissociation and ionization equilibria of deuterium fluid over a wide range of temperatures and densities

    SciTech Connect

    Zaghloul, Mofreh R.

    2015-06-15

    We investigate the dissociation and ionization equilibria of deuterium fluid over a wide range of temperatures and densities. The partition functions for molecular and atomic species are evaluated, in a statistical-mechanically consistent way, implementing recent developments in the literature and taking high-density effects into account. A new chemical model (free energy function) is introduced in which the fluid is considered as a mixture of diatomic molecules, atoms, ions, and free electrons. Intensive short range hard core repulsion is taken into account together with partial degeneracy of free electrons and Coulomb interactions among charged particles. Samples of computational results are presented as a set of isotherms for the degree of ionization, dissociated fraction of molecules, pressure, and specific internal energy for a wide range of densities and temperatures. Predictions from the present model calculations show an improved and sensible physical behavior compared to other results in the literature.

  3. An alternate method for achieving temperature control in the -130 C to 75 C range

    NASA Technical Reports Server (NTRS)

    Johnson, Kenneth R.; Anderson, Mark R.; Lane, Robert W.; Cortez, Maximo G.

    1992-01-01

    Thermal vacuum testing often requires temperature control of chamber shrouds and heat exchangers within the -130 C to 75 C range. There are two conventional methods which are normally employed to achieve control through this intermediate temperature range: (1) single-pass flow where control is achieved by alternately pulsing hot gaseous nitrogen (GN2) and cold LN2 into the feed line to yield the setpoint temperature; and (2) closed-loop circulation where control is achieved by either electrically heating or LN2 cooling the circulating GN2 to yield the setpoint temperature. A third method, using a mass flow ratio controller along with modulating control valves on GN2 and LN2 lines, provides excellent control but equipment for this method is expensive and cost-prohibitive for all but long-term continuous processes. The single-pass method provides marginal control and can result in unexpected overcooling of the test article from even a short pulse of LN2. The closed-loop circulation method provides excellent control but requires an expensive blower capable of operating at elevated pressures and cryogenic temperatures. Where precise control is needed (plus or minus 2 C), single-pass flow systems typically have not provided the precision required, primarily because of overcooling temperature excursions. Where several individual circuits are to be controlled at different temperatures, the use of expensive cryogenic blowers for each circuit is also cost-prohibitive, especially for short duration of one-of-a-kind tests. At JPL, a variant of the single-pass method was developed that was shown to provide precise temperature control in the -130 C to 75 C range while exhibiting minimal setpoint overshoot during temperature transitions. This alternate method uses a commercially available temperature controller along with a GN2/LN2 mixer to dampen the amplitude of cold temperature spikes caused by LN2 pulsing. The design of the GN2/LN2 mixer, the overall control system

  4. Temperature-dependent Goos-Hänchen shift in the terahertz range

    NASA Astrophysics Data System (ADS)

    Zang, Mengdi; He, Ting; Zhang, Bo; Zhong, Liang; Shen, Jingling

    2016-07-01

    In this work, an observation of Goos-Hänchen shift in the terahertz range on a metal surface with a change in temperature is reported. A s-polarized terahertz wave incident at 45° onto an aluminum surface produces a positive GH shift that increases with temperature. We used an interference method by observing the change of interference fringes of two THz beams to verify the existence of the GH shift and indirectly measured the quantity of it. Based on experimental data and theoretical analysis, the increase of GH shift on the aluminum surface as a function of temperature between 23 °C and 101 °C has been obtained. Considering the effect of the thermal expansion, the maximum variation of GH shift is 267.2 μm with the temperature changing 78 °C.

  5. Effect of diurnal temperature range on cardiovascular markers in the elderly in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Lim, Youn-Hee; Kim, Ho; Kim, Jin Hee; Bae, Sanghyuk; Hong, Yun-Chul

    2013-07-01

    While diurnal temperature range (DTR) has been found to be a risk factor for mortality, evaluation of the underlying mechanisms involved in this association are lacking. To explain the association between DTR and health effects, we investigated how cardiovascular markers responded to DTR. Data was obtained from 560 participants who regularly attended a community elderly welfare center located in Seoul, Korea. Data collection was conducted a total of five times over a 3-year period beginning in August, 2008. We examined systolic and diastolic blood pressure (BP), heart rate (HR), and heart rate variability (HRV). Mixed-effects models and generalized additive mixed models were used to assess the relationship of DTR with BP, HR, and HRV. BP was not associated significantly with rapid temperature changes during the day. While HR was associated linearly with increments of DTR, the relationship between DTR and HRV showed nonlinear associations, or the presence of a cutoff around median DTR. At the cutoff level of DTR determined by an inflection point in the graph, standard deviation of normal-to-normal intervals (SDNN) and root mean square successive difference (RMSSD) were peaked, whereas the low frequency:high frequency (LF:HF) ratio was elevated with decreasing DTR below the cutoff level. The study demonstrated that HR increases with increasing temperature range during the day, and that HRV is reduced at small or large DTR, which suggests minimal cardiovascular stress around the median level of temperature range during the day.

  6. Effects of regional temperature on electric vehicle efficiency, range, and emissions in the United States.

    PubMed

    Yuksel, Tugce; Michalek, Jeremy J

    2015-03-17

    We characterize the effect of regional temperature differences on battery electric vehicle (BEV) efficiency, range, and use-phase power plant CO2 emissions in the U.S. The efficiency of a BEV varies with ambient temperature due to battery efficiency and cabin climate control. We find that annual energy consumption of BEVs can increase by an average of 15% in the Upper Midwest or in the Southwest compared to the Pacific Coast due to temperature differences. Greenhouse gas (GHG) emissions from BEVs vary primarily with marginal regional grid mix, which has three times the GHG intensity in the Upper Midwest as on the Pacific Coast. However, even within a grid region, BEV emissions vary by up to 22% due to spatial and temporal ambient temperature variation and its implications for vehicle efficiency and charging duration and timing. Cold climate regions also encounter days with substantial reduction in EV range: the average range of a Nissan Leaf on the coldest day of the year drops from 70 miles on the Pacific Coast to less than 45 miles in the Upper Midwest. These regional differences are large enough to affect adoption patterns and energy and environmental implications of BEVs relative to alternatives.

  7. Effects of regional temperature on electric vehicle efficiency, range, and emissions in the United States.

    PubMed

    Yuksel, Tugce; Michalek, Jeremy J

    2015-03-17

    We characterize the effect of regional temperature differences on battery electric vehicle (BEV) efficiency, range, and use-phase power plant CO2 emissions in the U.S. The efficiency of a BEV varies with ambient temperature due to battery efficiency and cabin climate control. We find that annual energy consumption of BEVs can increase by an average of 15% in the Upper Midwest or in the Southwest compared to the Pacific Coast due to temperature differences. Greenhouse gas (GHG) emissions from BEVs vary primarily with marginal regional grid mix, which has three times the GHG intensity in the Upper Midwest as on the Pacific Coast. However, even within a grid region, BEV emissions vary by up to 22% due to spatial and temporal ambient temperature variation and its implications for vehicle efficiency and charging duration and timing. Cold climate regions also encounter days with substantial reduction in EV range: the average range of a Nissan Leaf on the coldest day of the year drops from 70 miles on the Pacific Coast to less than 45 miles in the Upper Midwest. These regional differences are large enough to affect adoption patterns and energy and environmental implications of BEVs relative to alternatives. PMID:25671586

  8. A Liquid Density Standard Over Wide Ranges of Temperature and Pressure Based on Toluene

    PubMed Central

    McLinden, Mark O.; Splett, Jolene D.

    2008-01-01

    The density of liquid toluene has been measured over the temperature range −60 °C to 200 °C with pressures up to 35 MPa. A two-sinker hydrostatic-balance densimeter utilizing a magnetic suspension coupling provided an absolute determination of the density with low uncertainties. These data are the basis of NIST Standard Reference Material® 211d for liquid density over the temperature range −50 °C to 150 °C and pressure range 0.1 MPa to 30 MPa. A thorough uncertainty analysis is presented; this includes effects resulting from the experimental density determination, possible degradation of the sample due to time and exposure to high temperatures, dissolved air, uncertainties in the empirical density model, and the sample-to-sample variations in the SRM vials. Also considered is the effect of uncertainty in the temperature and pressure measurements. This SRM is intended for the calibration of industrial densimeters. PMID:27096111

  9. An improved approach for measuring immersion freezing in large droplets over a wide temperature range.

    PubMed

    Tobo, Yutaka

    2016-01-01

    Immersion freezing (ice nucleation by particles immersed in supercooled water) is a key process for forming ice in mixed-phase clouds. Immersion freezing experiments with particles in microliter-sized (millimeter-sized) water droplets are often applied to detecting very small numbers of ice nucleating particles (INPs). However, the application of such large droplets remains confined to the detection of INPs active at temperatures much higher than the homogeneous freezing limit, because of artifacts related to freezing of water droplets without added INPs at temperatures of -25 °C or higher on a supporting substrate. Here I report a method for measuring immersion freezing in super-microliter-sized droplets over a wide temperature range. To reduce possible artifacts, droplets are pipetted onto a thin layer of Vaseline and cooled in a clean booth. In the Cryogenic Refrigerator Applied to Freezing Test (CRAFT) system, freezing of pure (Milli-Q) water droplets are limited at temperatures above -30 °C. An intercomparison of various techniques for immersion freezing experiments with reference particles (Snomax and illite NX) demonstrates that despite the use of relatively large droplets, the CRAFT setup allows for evaluating the immersion freezing activity of the particles over almost the entire temperature range (about -30 °C to 0 °C) relevant for mixed-phase cloud formation.

  10. Stability of a Crystal Oscillator, Type Si530, Inside and Beyond its Specified Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2011-01-01

    Data acquisition and control systems depend on timing signals for proper operation and required accuracy. These clocked signals are typically provided by some form of an oscillator set to produce a repetitive, defined signal at a given frequency. Crystal oscillators are commonly used because they are less expensive, smaller, and more reliable than other types of oscillators. Because of the inherent characteristics of the crystal, the oscillators exhibit excellent frequency stability within the specified range of operational temperature. In some cases, however, some compensation techniques are adopted to further improve the thermal stability of a crystal oscillator. Very limited data exist on the performance and reliability of commercial-off-the-shelf (COTS) crystal oscillators at temperatures beyond the manufacturer's specified operating temperature range. This information is very crucial if any of these parts were to be used in circuits designed for use in space exploration missions where extreme temperature swings and thermal cycling are encountered. This report presents the results of the work obtained on the operation of Silicon Laboratories crystal oscillator, type Si530, under specified and extreme ambient temperatures.

  11. An improved approach for measuring immersion freezing in large droplets over a wide temperature range

    PubMed Central

    Tobo, Yutaka

    2016-01-01

    Immersion freezing (ice nucleation by particles immersed in supercooled water) is a key process for forming ice in mixed-phase clouds. Immersion freezing experiments with particles in microliter-sized (millimeter-sized) water droplets are often applied to detecting very small numbers of ice nucleating particles (INPs). However, the application of such large droplets remains confined to the detection of INPs active at temperatures much higher than the homogeneous freezing limit, because of artifacts related to freezing of water droplets without added INPs at temperatures of −25 °C or higher on a supporting substrate. Here I report a method for measuring immersion freezing in super-microliter-sized droplets over a wide temperature range. To reduce possible artifacts, droplets are pipetted onto a thin layer of Vaseline and cooled in a clean booth. In the Cryogenic Refrigerator Applied to Freezing Test (CRAFT) system, freezing of pure (Milli-Q) water droplets are limited at temperatures above −30 °C. An intercomparison of various techniques for immersion freezing experiments with reference particles (Snomax and illite NX) demonstrates that despite the use of relatively large droplets, the CRAFT setup allows for evaluating the immersion freezing activity of the particles over almost the entire temperature range (about −30 °C to 0 °C) relevant for mixed-phase cloud formation. PMID:27596247

  12. An improved approach for measuring immersion freezing in large droplets over a wide temperature range

    NASA Astrophysics Data System (ADS)

    Tobo, Yutaka

    2016-09-01

    Immersion freezing (ice nucleation by particles immersed in supercooled water) is a key process for forming ice in mixed-phase clouds. Immersion freezing experiments with particles in microliter-sized (millimeter-sized) water droplets are often applied to detecting very small numbers of ice nucleating particles (INPs). However, the application of such large droplets remains confined to the detection of INPs active at temperatures much higher than the homogeneous freezing limit, because of artifacts related to freezing of water droplets without added INPs at temperatures of ‑25 °C or higher on a supporting substrate. Here I report a method for measuring immersion freezing in super-microliter-sized droplets over a wide temperature range. To reduce possible artifacts, droplets are pipetted onto a thin layer of Vaseline and cooled in a clean booth. In the Cryogenic Refrigerator Applied to Freezing Test (CRAFT) system, freezing of pure (Milli-Q) water droplets are limited at temperatures above ‑30 °C. An intercomparison of various techniques for immersion freezing experiments with reference particles (Snomax and illite NX) demonstrates that despite the use of relatively large droplets, the CRAFT setup allows for evaluating the immersion freezing activity of the particles over almost the entire temperature range (about ‑30 °C to 0 °C) relevant for mixed-phase cloud formation.

  13. An improved approach for measuring immersion freezing in large droplets over a wide temperature range.

    PubMed

    Tobo, Yutaka

    2016-01-01

    Immersion freezing (ice nucleation by particles immersed in supercooled water) is a key process for forming ice in mixed-phase clouds. Immersion freezing experiments with particles in microliter-sized (millimeter-sized) water droplets are often applied to detecting very small numbers of ice nucleating particles (INPs). However, the application of such large droplets remains confined to the detection of INPs active at temperatures much higher than the homogeneous freezing limit, because of artifacts related to freezing of water droplets without added INPs at temperatures of -25 °C or higher on a supporting substrate. Here I report a method for measuring immersion freezing in super-microliter-sized droplets over a wide temperature range. To reduce possible artifacts, droplets are pipetted onto a thin layer of Vaseline and cooled in a clean booth. In the Cryogenic Refrigerator Applied to Freezing Test (CRAFT) system, freezing of pure (Milli-Q) water droplets are limited at temperatures above -30 °C. An intercomparison of various techniques for immersion freezing experiments with reference particles (Snomax and illite NX) demonstrates that despite the use of relatively large droplets, the CRAFT setup allows for evaluating the immersion freezing activity of the particles over almost the entire temperature range (about -30 °C to 0 °C) relevant for mixed-phase cloud formation. PMID:27596247

  14. Estimation of some thermoelastic properties of boron suboxide in wide ranges of temperature

    NASA Astrophysics Data System (ADS)

    Tsagareishvili, D. Sh.; Tushishvili, M. Ch.; Tsagareishvili, G. V.

    1991-07-01

    Approximate values of the thermal coefficient of volume expansion, the volume, the Young's and shear elastic moduli, the elastic bulk modulus, the Poisson's ratio, the Grüneisen, the Anderson-Grüneisen and the Murnaghan thermoelastic parameters, the average sound velocity, and the Debye temperature in 0-1500 K temperature range have been estimated based on the available in the literature limited experimental data on some thermal and elastic properties of boron suboxide and using known or the methods of calculation carried out by the authors.

  15. Atmosphere-only GCM (ACCESS1.0) simulations with prescribed land surface temperatures

    NASA Astrophysics Data System (ADS)

    Ackerley, Duncan; Dommenget, Dietmar

    2016-06-01

    General circulation models (GCMs) are valuable tools for understanding how the global ocean-atmosphere-land surface system interacts and are routinely evaluated relative to observational data sets. Conversely, observational data sets can also be used to constrain GCMs in order to identify systematic errors in their simulated climates. One such example is to prescribe sea surface temperatures (SSTs) such that 70 % of the Earth's surface temperature field is observationally constrained (known as an Atmospheric Model Intercomparison Project, AMIP, simulation). Nevertheless, in such simulations, land surface temperatures are typically allowed to vary freely, and therefore any errors that develop over the land may affect the global circulation. In this study therefore, a method for prescribing the land surface temperatures within a GCM (the Australian Community Climate and Earth System Simulator, ACCESS) is presented. Simulations with this prescribed land surface temperature model produce a mean climate state that is comparable to a simulation with freely varying land temperatures; for example, the diurnal cycle of tropical convection is maintained. The model is then developed further to incorporate a selection of "proof of concept" sensitivity experiments where the land surface temperatures are changed globally and regionally. The resulting changes to the global circulation in these sensitivity experiments are found to be consistent with other idealized model experiments described in the wider scientific literature. Finally, a list of other potential applications is described at the end of the study to highlight the usefulness of such a model to the scientific community.

  16. Wide-range average temperature measurements of convective fluid flows by using a schlieren system.

    PubMed

    Martínez-González, A; Moreno-Hernández, D; León-Rodríguez, M; Carrillo-Delgado, C

    2016-01-20

    In the schlieren method, the deflection of light by the presence of an inhomogeneous medium is proportional to the gradient of its refractive index. In the presence of temperature variations in a fluid flow, the refraction index is related to the gas density by the Gladstone-Dale constant, which depends on the nature of the gas and the wavelength of light propagating in the medium. The deflection of light in a schlieren system is represented by intensity variations on the observation plane. Then, for a digital camera, the intensity level registered in each pixel depends mainly on the refractive index variation of the medium and exposure time. Therefore, if we regulate the intensity value of each pixel by controlling the exposure time, it is possible to adjust the temperature value measurements. In this way, a specific exposure time of a digital camera allows us to measure a determined range of temperature values. For that reason, in this study we determine the range of temperatures that can be measured with a digital camera for different exposure times. By doing this, a wide range of average temperature value fields can be obtained by summing up the temperature contribution of each exposure time. The basic idea in our approach to measure temperature by using a schlieren system is to relate the intensity level of each pixel in a schlieren image to the corresponding knife-edge position measured at the exit focal plane of the system. Our approach is applied to the measurement of temperature fields of the air convection caused by a heated rectangular metal plate (7.3  cm×12  cm) and a candle flame. We found that the maximum temperature values obtained for exposure times of 31.3, 15.7, 7.9, 3.9, and 2 ms were 67.3°C, 122.6°C, 217.4°C, 364.3°C, and 524.0°C, respectively. PMID:26835931

  17. Factors affecting temperature variation and habitat use in free-ranging diamondback terrapins.

    PubMed

    Akins, C D; Ruder, C D; Price, S J; Harden, L A; Gibbons, J W; Dorcas, M E

    2014-08-01

    Measuring the thermal conditions of aquatic reptiles with temperature dataloggers is a cost-effective way to study their behavior and habitat use. Temperature dataloggers are a particularly useful and informative approach to studying organisms such as the estuarine diamondback terrapin (Malaclemys terrapin) that inhabits a dynamic environment often inaccessible to researchers. We used carapace-mounted dataloggers to measure hourly carapace temperature (Tc) of free-ranging terrapins in South Carolina from October 2007 to 2008 to examine the effects of month, sex, creek site, and tide on Tc and to determine the effects of month, sex, and time of day on terrapin basking frequency. Simultaneous measurements of environmental temperatures (Te; shallow mud, deep mud, water) allowed us to make inferences about terrapin microhabitat use. Terrapin Tc differed significantly among months and creek and between sexes. Terrapin microhabitat use also varied monthly, with shallow mud temperature being the best predictor of Tc November-March and water temperature being the best predictor of Tc April-October. Terrapins basked most frequently in spring and fall and males basked more frequently than females. Our study contributes to a fuller understanding of terrapin thermal biology and provides support for using dataloggers to investigate behavior and habitat use of aquatic ectotherms inhabiting dynamic environments.

  18. Feeding behaviour of free-ranging penguins determined by oesophageal temperature.

    PubMed

    Charrassin, J B; Kato, A; Handrich, Y; Sato, K; Naito, Y; Ancel, A; Bost, C A; Gauthier-Clerc, M; Ropert-Coudert, Y; Le Maho, Y

    2001-01-22

    Sea birds play a major role in marine food webs, and it is important to determine when and how much they feed at sea. A major advance has been made by using the drop in stomach temperature after ingestion of ectothermic prey. This method is less sensitive when birds eat small prey or when the stomach is full. Moreover, in diving birds, independently of food ingestion, there are fluctuations in the lower abdominal temperature during the dives. Using oesophageal temperature, we present here a new method for detecting the timing of prey ingestion in free-ranging sea birds, and, to our knowledge, report the first data obtained on king penguins (Aptenodytes patagonicus). In birds ashore, which were hand-fed 2-15 g pieces of fish, all meal ingestions were detected with a sensor in the upper oesophagus. Detection was poorer with sensors at increasing distances from the beak. At sea, slow temperature drops in the upper oesophagus and stomach characterized a diving effect per se. For the upper oesophagus only, abrupt temperature variations were superimposed, therefore indicating prey ingestions. We determined the depths at which these occurred. Combining the changes in oesophageal temperatures of marine predators with their diving pattern opens new perspectives for understanding their foraging strategy, and, after validation with concurrent applications of classical techniques of prey survey, for assessing the distribution of their prey. PMID:11209884

  19. Computer prediction of human thermoregulatory and temperature responses to a wide range of environmental conditions

    NASA Astrophysics Data System (ADS)

    Fiala, D.; Lomas, K. J.; Stohrer, M.

    A mathematical model for predicting human thermal and regulatory responses in cold, cool, neutral, warm, and hot environments has been developed and validated. The multi-segmental passive system, which models the dynamic heat transport within the body and the heat exchange between body parts and the environment, is discussed elsewhere. This paper is concerned with the development of the active system, which simulates the regulatory responses of shivering, sweating, and peripheral vasomotion of unacclimatised subjects. Following a comprehensive literature review, 26 independent experiments were selected that were designed to provoke each of these responses in different circumstances. Regression analysis revealed that skin and head core temperature affect regulatory responses in a non-linear fashion. A further signal, i.e. the rate of change of the mean skin temperature weighted by the skin temperature error signal, was identified as governing the dynamics of thermoregulatory processes in the cold. Verification and validation work was carried out using experimental data obtained from 90 exposures covering a range of steady and transient ambient temperatures between 5°C and 50°C and exercise intensities between 46 W/m2 and 600 W/m2. Good general agreement with measured data was obtained for regulatory responses, internal temperatures, and the mean and local skin temperatures of unacclimatised humans for the whole spectrum of climatic conditions and for different activity levels.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

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

    PubMed

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

    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. PMID:27586931

  2. Factors affecting temperature variation and habitat use in free-ranging diamondback terrapins.

    PubMed

    Akins, C D; Ruder, C D; Price, S J; Harden, L A; Gibbons, J W; Dorcas, M E

    2014-08-01

    Measuring the thermal conditions of aquatic reptiles with temperature dataloggers is a cost-effective way to study their behavior and habitat use. Temperature dataloggers are a particularly useful and informative approach to studying organisms such as the estuarine diamondback terrapin (Malaclemys terrapin) that inhabits a dynamic environment often inaccessible to researchers. We used carapace-mounted dataloggers to measure hourly carapace temperature (Tc) of free-ranging terrapins in South Carolina from October 2007 to 2008 to examine the effects of month, sex, creek site, and tide on Tc and to determine the effects of month, sex, and time of day on terrapin basking frequency. Simultaneous measurements of environmental temperatures (Te; shallow mud, deep mud, water) allowed us to make inferences about terrapin microhabitat use. Terrapin Tc differed significantly among months and creek and between sexes. Terrapin microhabitat use also varied monthly, with shallow mud temperature being the best predictor of Tc November-March and water temperature being the best predictor of Tc April-October. Terrapins basked most frequently in spring and fall and males basked more frequently than females. Our study contributes to a fuller understanding of terrapin thermal biology and provides support for using dataloggers to investigate behavior and habitat use of aquatic ectotherms inhabiting dynamic environments. PMID:25086975

  3. Stream temperature change detection for state and private forests in the Oregon Coast Range

    NASA Astrophysics Data System (ADS)

    Groom, Jeremiah D.; Dent, Liz; Madsen, Lisa J.

    2011-01-01

    Oregon's forested coastal watersheds support important cold-water fisheries of salmon and steelhead (Oncorhynchus spp.) as well as forestry-dependent local economies. Riparian timber harvest restrictions in Oregon and elsewhere are designed to protect stream habitat characteristics while enabling upland timber harvest. We present an assessment of riparian leave tree rule effectiveness at protecting streams from temperature increases in the Oregon Coast Range. We evaluated temperature responses to timber harvest at 33 privately owned and state forest sites with Oregon's water quality temperature antidegradation standard, the Protecting Cold Water (PCW) criterion. At each site we evaluated stream temperature patterns before and after harvest upstream, within, and downstream of harvest units. We developed a method for detecting stream temperature change between years that adhered as closely as possible to Oregon's water quality rule language. The procedure provided an exceedance history across sites that allowed us to quantify background and treatment (timber harvest) PCW exceedance rates. For streams adjacent to harvested areas on privately owned lands, preharvest to postharvest year comparisons exhibited a 40% probability of exceedance. Sites managed according to the more stringent state forest riparian standards did not exhibit exceedance rates that differed from preharvest, control, or downstream rates (5%). These results will inform policy discussion regarding the sufficiency of Oregon's forest practices regulation at protecting stream temperature. The analysis process itself may assist other states and countries in developing and evaluating their forest management and water quality antidegradation regulations.

  4. Feeding behaviour of free-ranging penguins determined by oesophageal temperature.

    PubMed Central

    Charrassin, J B; Kato, A; Handrich, Y; Sato, K; Naito, Y; Ancel, A; Bost, C A; Gauthier-Clerc, M; Ropert-Coudert, Y; Le Maho, Y

    2001-01-01

    Sea birds play a major role in marine food webs, and it is important to determine when and how much they feed at sea. A major advance has been made by using the drop in stomach temperature after ingestion of ectothermic prey. This method is less sensitive when birds eat small prey or when the stomach is full. Moreover, in diving birds, independently of food ingestion, there are fluctuations in the lower abdominal temperature during the dives. Using oesophageal temperature, we present here a new method for detecting the timing of prey ingestion in free-ranging sea birds, and, to our knowledge, report the first data obtained on king penguins (Aptenodytes patagonicus). In birds ashore, which were hand-fed 2-15 g pieces of fish, all meal ingestions were detected with a sensor in the upper oesophagus. Detection was poorer with sensors at increasing distances from the beak. At sea, slow temperature drops in the upper oesophagus and stomach characterized a diving effect per se. For the upper oesophagus only, abrupt temperature variations were superimposed, therefore indicating prey ingestions. We determined the depths at which these occurred. Combining the changes in oesophageal temperatures of marine predators with their diving pattern opens new perspectives for understanding their foraging strategy, and, after validation with concurrent applications of classical techniques of prey survey, for assessing the distribution of their prey. PMID:11209884

  5. Optical Measurement of the Speed of Sound in Air Over the Temperature Range 300-650 K

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Balla, R. Jeffrey; Herring, G. C.

    2000-01-01

    Using laser-induced thermal acoustics (LITA), the speed of sound in room air (1 atm) is measured over the temperature range 300-650 K. Since the LITA apparatus maintains a fixed sound wavelength as temperature is varied, this temperature range simultaneously corresponds to a sound frequency range of 10-15 MHz. The data are compared to a published model and typically agree within 0.1%-0.4% at each of 21 temperatures.

  6. Two-Phase Working Fluids for the Temperature Range 50 to 350 C

    NASA Technical Reports Server (NTRS)

    Saaski, E. W.; Owzarski, P. C.

    1977-01-01

    The decomposition and corrosion of two-phase heat transfer liquids and metal envelopes have been investigated on the basis of molecular bond strengths and chemical thermodynamics. Potentially stable heat transfer fluids for the temperature range 100 C to 350 C have been identified, and reflux heat pipes tests initiated with 10 fluids and carbon steel and aluminum envelopes to experimentally establish corrosion behavior and noncondensable gas generation rates.

  7. Estimation and Attribution of the Temperature Variances in Height Range 60~140 km

    NASA Astrophysics Data System (ADS)

    Chen, Zeyu

    The SABER/TIMED temperatures collected during 2002 2006 are used to estimate for height range 60 120 km the variances of temperature (Temp-VARs) that are contributed from nonstationary perturbations. The estimation results disclose that the height range 60 140 km can be separated into two regions that are characterized by significant differences of the attributions of the Temp-VARs. In the region below 100 km height, the Temp-VARs generally increase with height, the corresponding standard deviations of temperature (Temp-SDEVs) ranges from 4 K at 60 km and 18 K at 100 km. The regions exhibiting intense Temp-VARs appear at the equator and the extra-tropics of both hemispheres. Moreover, these non-stationary temperature disturbances can be accounted primarily by the tidal variances that are derived independently by using the same data-set, in particular by the migrating diurnal, semidiurnal, and terdiurnal tide. It is also found that the region above 100 km is characterized by surprisingly large Temp-VARs with the corresponding Temp-SDEVs greater than 30 K. In a height-latitude cross-section, a stagnant maximum of Temp-SDEVs embraced by the 30-K contour remains over the course of a year at the Equator in a narrow height range 110 125 km. At the same height in Southern hemisphere, the same kind maxima appears at latitudes from the extra-tropics to polar region except during the June solstice. In contrast, the maxima appearing in Northern hemisphere high latitudes exhibits intra-seasonal variations, there such maximum are seen during the course of a year. Further investigation results confirm that the large Temp-VARs have no relevance to the tidal variances, implying the control from other processes, e.g., non-stationary planetary waves. The details will be introduced in the presentation.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Hollow-Cathode Based Electrical Discharge in Atmospheric Pressure Water Vapor at Wide Range of Temperature

    NASA Astrophysics Data System (ADS)

    Koo, Il Gyo; Lee, Woong Moo

    2006-10-01

    Atmospheric pressure water vapor, in the temperature range from 150 to 700 °C, was used as the carrier gas for DC powered electrical discharge in hollow cathode configuration. The electrode assembly was constructed in usual hollow-cathode configuration by sandwiching a dielectric spacer, 200 μm thick, with two thin metal sheets and boring a micro hole of 300 μm diameter. The current-voltage profile of the discharge showed a positive differential resistivity characterizing an abnormal glow discharge. The power consumption for the water discharge at 700 °C was less than 50% the consumption at 150 °C. The reduction of the power for sustaining the discharge with increase of the gas temperature was partly explained by relating the ionic mobility and the distribution of ionic mean free path to the temperature.

  10. Impact response of cobalt over the 300-1400 K temperature range

    NASA Astrophysics Data System (ADS)

    Zaretsky, E. B.

    2010-10-01

    The yield and tensile (spall) strengths and the dynamic viscosity of 99.95% pure cobalt were studied in a series of interferometer-instrumented planar impact experiments over the 300 to 1423 K temperature range. The spall strength of cobalt declines monotonously from 3.2 GPa at 300 K to 0.8 GPa at 1400 K. The dynamic yield strength grows linearly with temperature in both the hcp and fcc cobalt phases. The hcp to fcc transformation at 690 K is accompanied by an abrupt twofold drop of the yield strength. The similarity between the temperature dependence of the cobalt's dynamic viscosity and of the yield strength suggests that both properties are controlled by the interaction of the dislocations with the oncoming phonon flow (phonon drag).

  11. Long-range energy transport in single supramolecular nanofibres at room temperature

    NASA Astrophysics Data System (ADS)

    Haedler, Andreas T.; Kreger, Klaus; Issac, Abey; Wittmann, Bernd; Kivala, Milan; Hammer, Natalie; Köhler, Jürgen; Schmidt, Hans-Werner; Hildner, Richard

    2015-07-01

    Efficient transport of excitation energy over long distances is a key process in light-harvesting systems, as well as in molecular electronics. However, in synthetic disordered organic materials, the exciton diffusion length is typically only around 10 nanometres (refs 4, 5), or about 50 nanometres in exceptional cases, a distance that is largely determined by the probability laws of incoherent exciton hopping. Only for highly ordered organic systems has the transport of excitation energy over macroscopic distances been reported--for example, for triplet excitons in anthracene single crystals at room temperature, as well as along single polydiacetylene chains embedded in their monomer crystalline matrix at cryogenic temperatures (at 10 kelvin, or -263 degrees Celsius). For supramolecular nanostructures, uniaxial long-range transport has not been demonstrated at room temperature. Here we show that individual self-assembled nanofibres with molecular-scale diameter efficiently transport singlet excitons at ambient conditions over more than four micrometres, a distance that is limited only by the fibre length. Our data suggest that this remarkable long-range transport is predominantly coherent. Such coherent long-range transport is achieved by one-dimensional self-assembly of supramolecular building blocks, based on carbonyl-bridged triarylamines, into well defined H-type aggregates (in which individual monomers are aligned cofacially) with substantial electronic interactions. These findings may facilitate the development of organic nanophotonic devices and quantum information technology.

  12. SiC JFET Transistor Circuit Model for Extreme Temperature Range

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.

    2008-01-01

    A technique for simulating extreme-temperature operation of integrated circuits that incorporate silicon carbide (SiC) junction field-effect transistors (JFETs) has been developed. The technique involves modification of NGSPICE, which is an open-source version of the popular Simulation Program with Integrated Circuit Emphasis (SPICE) general-purpose analog-integrated-circuit-simulating software. NGSPICE in its unmodified form is used for simulating and designing circuits made from silicon-based transistors that operate at or near room temperature. Two rapid modifications of NGSPICE source code enable SiC JFETs to be simulated to 500 C using the well-known Level 1 model for silicon metal oxide semiconductor field-effect transistors (MOSFETs). First, the default value of the MOSFET surface potential must be changed. In the unmodified source code, this parameter has a value of 0.6, which corresponds to slightly more than half the bandgap of silicon. In NGSPICE modified to simulate SiC JFETs, this parameter is changed to a value of 1.6, corresponding to slightly more than half the bandgap of SiC. The second modification consists of changing the temperature dependence of MOSFET transconductance and saturation parameters. The unmodified NGSPICE source code implements a T(sup -1.5) temperature dependence for these parameters. In order to mimic the temperature behavior of experimental SiC JFETs, a T(sup -1.3) temperature dependence must be implemented in the NGSPICE source code. Following these two simple modifications, the Level 1 MOSFET model of the NGSPICE circuit simulation program reasonably approximates the measured high-temperature behavior of experimental SiC JFETs properly operated with zero or reverse bias applied to the gate terminal. Modification of additional silicon parameters in the NGSPICE source code was not necessary to model experimental SiC JFET current-voltage performance across the entire temperature range from 25 to 500 C.

  13. Reassessing changes in diurnal temperature range: A new data set and characterization of data biases

    NASA Astrophysics Data System (ADS)

    Thorne, P. W.; Menne, M. J.; Williams, C. N.; Rennie, J. J.; Lawrimore, J. H.; Vose, R. S.; Peterson, T. C.; Durre, I.; Davy, R.; Esau, I.; Klein-Tank, A. M. G.; Merlone, A.

    2016-05-01

    It has been a decade since changes in diurnal temperature range (DTR) globally have been assessed in a stand-alone data analysis. The present study takes advantage of substantively improved basic data holdings arising from the International Surface Temperature Initiative's databank effort and applies the National Centers for Environmental Information's automated pairwise homogeneity assessment algorithm to reassess DTR records. It is found that breakpoints are more prevalent in DTR than other temperature elements and that the resulting adjustments have a broader distribution. This strongly implies that there is an overarching tendency, across the global meteorological networks, for nonclimatic artifacts to impart either random or anticorrelated rather than correlated biases in maximum and minimum temperature series. Future homogenization efforts would likely benefit from simultaneous consideration of DTR and maximum and minimum temperatures, in addition to average temperatures. Estimates of change in DTR are relatively insensitive to whether adjustments are calculated directly or inferred from adjustments returned for the maximum and minimum temperature series. The homogenized series exhibit a reduction in DTR since the midtwentieth century globally (-0.044 K/decade). Adjustments serve to approximately halve the long-term global reduction in DTR in the basic "raw" data. Most of the estimated DTR reduction occurred over 1960-1980. In several regions DTR has apparently increased over 1979-2012, while globally it has exhibited very little change (-0.016 K/decade). Estimated changes in DTR are an order of magnitude smaller than in maximum and minimum temperatures, which have both been increasing rapidly on multidecadal timescales (0.186 K/decade and 0.236 K/decade, respectively, since the midtwentieth century).

  14. Modelling the effect of temperature on the range expansion of species by reaction-diffusion equations.

    PubMed

    Richter, Otto; Moenickes, Sylvia; Suhling, Frank

    2012-02-01

    The spatial dynamics of range expansion is studied in dependence of temperature. The main elements population dynamics, competition and dispersal are combined in a coherent approach based on a system of coupled partial differential equations of the reaction-diffusion type. The nonlinear reaction terms comprise population dynamic models with temperature dependent reproduction rates subject to an Allee effect and mutual competition. The effect of temperature on travelling wave solutions is investigated for a one dimensional model version. One main result is the importance of the Allee effect for the crossing of regions with unsuitable habitats. The nonlinearities of the interaction terms give rise to a richness of spatio-temporal dynamic patterns. In two dimensions, the resulting non-linear initial boundary value problems are solved over geometries of heterogeneous landscapes. Geo referenced model parameters such as mean temperature and elevation are imported into the finite element tool COMSOL Multiphysics from a geographical information system. The model is applied to the range expansion of species at the scale of middle Europe.

  15. Future Arctic temperature change resulting from a range of aerosol emissions scenarios

    NASA Astrophysics Data System (ADS)

    Wobus, Cameron; Flanner, Mark; Sarofim, Marcus C.; Moura, Maria Cecilia P.; Smith, Steven J.

    2016-06-01

    The Arctic temperature response to emissions of aerosols -- specifically black carbon (BC), organic carbon (OC), and sulfate -- depends on both the sector and the region where these emissions originate. Thus, the net Arctic temperature response to global aerosol emissions reductions will depend strongly on the blend of emissions sources being targeted. We use recently published equilibrium Arctic temperature response factors for BC, OC, and sulfate to estimate the range of present-day and future Arctic temperature changes from seven different aerosol emissions scenarios. Globally, Arctic temperature changes calculated from all of these emissions scenarios indicate that present-day emissions from the domestic and transportation sectors generate the majority of present-day Arctic warming from BC. However, in all of these scenarios, this warming is more than offset by cooling resulting from SO2 emissions from the energy sector. Thus, long-term climate mitigation strategies that are focused on reducing carbon dioxide (CO2) emissions from the energy sector could generate short-term, aerosol-induced Arctic warming. A properly phased approach that targets BC-rich emissions from the transportation sector as well as the domestic sectors in key regions -- while simultaneously working toward longer-term goals of CO2 mitigation -- could potentially avoid some amount of short-term Arctic warming.

  16. A Study on Flow Behavior of AA5086 Over a Wide Range of Temperatures

    NASA Astrophysics Data System (ADS)

    Asgharzadeh, A.; Jamshidi Aval, H.; Serajzadeh, S.

    2016-03-01

    Flow stress behavior of AA5086 was determined using tensile testing at different temperatures from room temperature to 500 °C and strain rates varying between 0.002 and 1 s-1. The strain rate sensitivity parameter and occurrence of dynamic strain aging were then investigated in which an Arrhenius-type model was employed to study the serrated flow. Additionally, hot deformation behavior at temperatures higher than 320 °C was evaluated utilizing hyperbolic-sine constitutive equation. Finally, a feed forward artificial neural network model with back propagation learning algorithm was proposed to predict flow stress for all deformation conditions. The results demonstrated that the strain rate sensitivity at temperature range of 25-270 °C was negative due to occurrence of dynamic strain aging leading to significant reduction in fracture strain. The serrated yielding activation energy was found to be 46.1 kJ/mol. It indicated that the migration of Mg-atoms could be the main reason for this phenomenon. The hot deformation activation energy of AA5086 was also calculated about 202.3 kJ/mol while the dynamic recovery was the main softening process. Moreover, the ANN model having two hidden layers was shown to be an efficient structure for determining flow stress of the examined alloy for all temperatures and strain rates.

  17. Satellite range delay simulator for a matrix-switched time division multiple-access network simulation system

    NASA Technical Reports Server (NTRS)

    Nagy, Lawrence A.

    1990-01-01

    The Systems Integration, Test, and Evaluation (SITE) facility at NASA Lewis Research Center is presently configured as a satellite-switched time division multiple access (SS-TDMA) network simulator. The purpose of SITE is to demonstrate and evaluate advanced communication satellite technologies, presently embodied by POC components developed under NASA contracts in addition to other hardware, such as ground terminals, designed and built in-house at NASA Lewis. Each ground terminal in a satellite communications system will experience a different aspect of the satellite's motion due mainly to daily tidal effects and station keeping, hence a different duration and rate of variation in the range delay. As a result of this and other effects such as local oscillator instability, each ground terminal must constantly adjust its transmit burst timing so that data bursts from separate ground terminals arrive at the satellite in their assigned time slots, preventing overlap and keeping the system in synchronism. On the receiving end, ground terminals must synchronize their local clocks using reference transmissions received through the satellite link. A feature of the SITE facility is its capability to simulate the varying propagation delays and associated Doppler frequency shifts that the ground terminals in the network have to cope with. Delay is ahcieved by means of two NASA Lewis designed and built range delay simulator (RDS) systems, each independently controlled locally with front panel switches or remotely by an experiment control and monitor (EC/M) computer.

  18. Effects of reproductive status and high ambient temperatures on the body temperature of a free-ranging basoendotherm.

    PubMed

    Levesque, Danielle L; Lobban, Kerileigh D; Lovegrove, Barry G

    2014-12-01

    Tenrecs (Order Afrosoricida) exhibit some of the lowest body temperatures (T b) of any eutherian mammal. They also have a high level of variability in both active and resting T bs and, at least in cool temperatures in captivity, frequently employ both short- and long-term torpor. The use of heterothermy by captive animals is, however, generally reduced during gestation and lactation. We present data long-term T b recordings collected from free-ranging S. setosus over the course of two reproductive seasons. In general, reproductive females had slightly higher (~32 °C) and less variable T b, whereas non-reproductive females and males showed both a higher propensity for torpor as well as lower (~30.5 °C) and more variable rest-phase T bs. Torpor expression defined using traditional means (using a threshold or cut-off T b) was much lower than predicted based on the high degree of heterothermy in captive tenrecs. However, torpor defined in this manner is likely to be underestimated in habitats where ambient temperature is close to T b. Our results caution against inferring metabolic states from T b alone and lend support to the recent call to define torpor in free-ranging animals based on mechanistic and not descriptive variables. In addition, lower variability in T b observed during gestation and lactation confirms that homeothermy is essential for reproduction in this species and probably for basoendothermic mammals in general. The relatively low costs of maintaining homeothermy in a sub-tropical environment might help shed light on how homeothermy could have evolved incrementally from an ancestral heterothermic condition.

  19. Effects of reproductive status and high ambient temperatures on the body temperature of a free-ranging basoendotherm.

    PubMed

    Levesque, Danielle L; Lobban, Kerileigh D; Lovegrove, Barry G

    2014-12-01

    Tenrecs (Order Afrosoricida) exhibit some of the lowest body temperatures (T b) of any eutherian mammal. They also have a high level of variability in both active and resting T bs and, at least in cool temperatures in captivity, frequently employ both short- and long-term torpor. The use of heterothermy by captive animals is, however, generally reduced during gestation and lactation. We present data long-term T b recordings collected from free-ranging S. setosus over the course of two reproductive seasons. In general, reproductive females had slightly higher (~32 °C) and less variable T b, whereas non-reproductive females and males showed both a higher propensity for torpor as well as lower (~30.5 °C) and more variable rest-phase T bs. Torpor expression defined using traditional means (using a threshold or cut-off T b) was much lower than predicted based on the high degree of heterothermy in captive tenrecs. However, torpor defined in this manner is likely to be underestimated in habitats where ambient temperature is close to T b. Our results caution against inferring metabolic states from T b alone and lend support to the recent call to define torpor in free-ranging animals based on mechanistic and not descriptive variables. In addition, lower variability in T b observed during gestation and lactation confirms that homeothermy is essential for reproduction in this species and probably for basoendothermic mammals in general. The relatively low costs of maintaining homeothermy in a sub-tropical environment might help shed light on how homeothermy could have evolved incrementally from an ancestral heterothermic condition. PMID:25155185

  20. Spring leaf phenology and the diurnal temperature range in a temperate maple forest.

    PubMed

    Hanes, Jonathan M

    2014-03-01

    Spring leaf phenology in temperate climates is intricately related to numerous aspects of the lower atmosphere [e.g., surface energy balance, carbon flux, humidity, the diurnal temperature range (DTR)]. To further develop and improve the accuracy of ecosystem and climate models, additional investigations of the specific nature of the relationships between spring leaf phenology and various ecosystem and climate processes are required in different environments. This study used visual observations of maple leaf phenology, below-canopy light intensities, and micrometeorological data collected during the spring seasons of 2008, 2009, and 2010 to examine the potential influence of leaf phenology on a seasonal transition in the trend of the DTR. The timing of a reversal in the DTR trend occurred near the time when the leaves were unfolding and expanding. The results suggest that the spring decline in the DTR can be attributed primarily to the effect of canopy closure on daily maximum temperature. These findings improve our understanding of the relationship between leaf phenology and the diurnal temperature range in temperate maple forests during the spring. They also demonstrate the necessity of incorporating accurate phenological data into ecosystem and climate models and warrant a careful examination of the extent to which canopy phenology is currently incorporated into existing models.

  1. Kinetic measurements on elementary fossil fuel combustion reactions over wide temperatures ranges

    SciTech Connect

    Fontijin, A.

    1992-01-01

    The goals of this work are to provide accurate data on the temperature dependence of the kinetics of elementary combustion reactions (i) for use by combustion modelers, and (ii) to gain a better fundamental understanding of, and hence predictive ability for, the chemistry involved. Experimental measurements are made using the pseudo-static HTP (high-temperature photochemistry) technique. This approach allows observations on single reactions in the 300 to 1800 K temperature range to be made. Typical total (bath gas) pressures are in the 100 to 1000 mbar range. Ground-state O and H atoms are produced by flash or excimer laser photolysis of suitable precursors (O{sub 2}, CO{sub 2}, SO{sub 2}, NH{sub 3}). The relative atom concentrations are monitored by resonance fluorescence pumped by a cw microwave discharge flow lamp. The molecular reactant-in-excess is introduced through a cooled inlet. Adequate time for mixing, 0.1 to 10 s, between this inlet and the photolysis/observation zone is achieved by using slow flows (typically less than 20 cm s{sup {minus}1}). Results are reported for: O-Atom Reactions with the Four Isomeric Butenes, H + HCl {yields} H{sub 2} + Cl, and the O-atom 1,3-butadiene reaction.

  2. National Inter-laboratory Comparison of Thermocouples in the Temperature Range from to

    NASA Astrophysics Data System (ADS)

    Arifoviç, N.; Kalemci, M.

    2015-08-01

    One of the main criteria demonstrating the competence of a calibration laboratory is successful participation in inter-laboratory comparisons. Real capability of the laboratory including claimed uncertainties could be demonstrated based on the results of comparisons, evaluated either through -criteria or other acceptable measures. As a number of accredited laboratories with scopes covering calibration services in the field of thermometry have been increasing, the demand for organization of inter-laboratory comparisons with participation of accredited laboratories occurs. Based on this fact, a national inter-laboratory comparison of thermocouple calibrations in the temperature range from to in the field of temperature was launched by TUBITAK UME in 2011. The purpose of the inter-laboratory comparison was to compare the results of the participating laboratories during calibration of the thermocouples in the range from to . Three type S thermocouples were constructed and calibrated by TUBITAK UME which is the pilot laboratory of the comparison. It was recommended that the participants use their standard procedure for the calibration of thermocouples and follow the instructions of comparison protocol during the calibration. The inter-laboratory comparison was carried out among eleven national accredited laboratories. In this paper, the temperature differences obtained by participating laboratories with associated uncertainties of the results and values will be presented. The metrological equivalence of all laboratories was demonstrated, with all values being less than 1.0.

  3. Temperature Dependence of Novel Single-Photon Detectors in the Long-Wavelength Infrared Range

    NASA Astrophysics Data System (ADS)

    Ueda, Takeji; An, Zhenghua; Komiyama, Susumu

    2011-05-01

    Novel single-photon detectors, called Charge-sensitive Infrared Phototransistor (CSIP), have been developed in the long wavelength infrared (LWIR) range. The devices are fabricated in GaAs/AlGaAs double-quantum-well (DQW) structure, and do not require ultralow temperatures ( T < 1 K) for operation. Figures of merit are determined in a T-range of 4.2 K˜30 K by using a homemade all-cryogenic spectrometer. We found that the photo-signal persists up to around 30 K. Excellent specific detectivity D * = 9.6 × 1014 cm Hz1/2/W and noise equivalent power NEP = 8.3 × 10-19 W/Hz1/2 are derived up to T = 23 K. The dynamic range of detection exceeds 106, roughly ranging from attowatt to picowatt levels. These values are by a few orders of magnitude higher than that of the state-of-the-art values of other detectors. Simple planar structure of CSIPs is feasible for array fabrication and will make it possible to monolithically integrate with reading circuit. CSIPs are, therefore, not only extremely sensitive but also suitable for practical use in wide ranging applications.

  4. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature

    PubMed Central

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-01-01

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch−2, ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns. PMID:22109527

  5. Diurnal temperature range and emergency room admissions for chronic obstructive pulmonary disease in Taiwan

    NASA Astrophysics Data System (ADS)

    Liang, Wen-Miin; Liu, Wen-Pin; Kuo, Hsien-Wen

    2009-01-01

    The objective of this study was to assess the relationship between diurnal temperature range (DTR) and emergency room (ER) admissions for chronic obstructive pulmonary disease (COPD) in an ER in Taichung City, Taiwan. The design was a longitudinal study in which DTR was related to COPD admissions to the ER of the city’s largest hospital. Daily ER admissions for COPD and ambient temperature were collected from 1 January 2001 to 31 December 2002. There was a significant negative association between the average daily temperature and ER admissions for COPD ( r = -0.95). However, a significant positive association between DTR and COPD admissions was found ( r = 0.90). Using the Poisson regression model after adjusting for the effects of air pollutants and the day of the week, COPD admissions to the ER increased by 14% when DTR was over 9.6°C. COPD patients must be made aware of the increased risk posed by large DTR. Hospitals and ERs should take into account the increased demand of specific facilities during periods of large temperature variations.

  6. Dielectric properties of the collagen-glycosaminoglycans scaffolds in the temperature range of thermal decomposition.

    PubMed

    Pietrucha, K; Marzec, E

    2005-10-22

    Dielectric spectroscopy has been applied to study the decomposition process of unmodified collagen and chondroitin sulfate (CS)- and hyaluronic acid (HA)-modified collagen. Measurements were performed over the frequency range from 10 Hz to 100 kHz and at temperatures from 22 to 260 degrees C. According to the Kramers-Kronig relationship a dispersion is apparent in both epsilon' and epsilon'' for the three materials below 140 degrees C and at higher temperatures as a broad peak around 220-230 degrees C, respectively. The values of epsilon' and epsilon'' at the same temperature for constant frequency are higher in HA-modified collagen than in the unmodified collagen. However, small differences are shown in these parameters between CS-modified collagen and unmodified collagen. The observed dispersion around 220-230 degrees C corresponds to the decomposition of unmodified and CS- and HA-modified collagen. Power-low responses are observed for the frequency dependence of ac conductivity for unmodified and modified collagen. The behaviour observed for temperature dependencies of the exponent n for the three materials is considered to be related to the proton polarization and conduction processes.

  7. Thermal analysis of the mixtures of paraffin with aluminum in wide temperature range

    NASA Astrophysics Data System (ADS)

    Gubin, S. A.; Maklashova, I. V.; Levitskaya, I. S.

    2016-09-01

    The mixtures and composites of wax, paraffin and metals are widely used as energy efficient formulations and phase change materials for heat storage. Aluminum is frequently employed in the formulations of many composite explosives or propellants. Metal fuel additives are used in advanced explosive formulations to achieve higher combustion temperatures and longer pressure pulses. In this project, Al-paraffin wax composite materials were prepared and characterized. The thermal stability of the prepared powders was determined by differential scanning calorimeter, simultaneous thermogravimetry analysis- differential thermal analysis in the temperature range 30-1300°C at atmospheric pressure. The results of differential scanning calorimeter showed that the thermal performance and structure of the composite materials are stable up to 200°C.The paraffindecompositionwith an energy release is possible at temperatures over 200°C and the oxidation of aluminum may be at a temperature above its melting point.It is shown that the maximum total amount of heat generated by the thermal decomposition of the composition was at the mass fraction of aluminum of 16% - 18%.

  8. Note: Vectorial-magneto optical Kerr effect technique combined with variable temperature and full angular range all in a single setup

    NASA Astrophysics Data System (ADS)

    Cuñado, Jose Luis F.; Pedrosa, Javier; Ajejas, Fernando; Bollero, Alberto; Perna, Paolo; Teran, Francisco J.; Miranda, Rodolfo; Camarero, Julio

    2015-04-01

    Here, we report on a versatile full angular resolved/broad temperature range/vectorial magneto optical Kerr effect (MOKE) magnetometer, named TRISTAN. Its versatility relies on its capacity to probe temperature and angular dependencies of magnetization reversal processes without the need to do any intervention on the apparatus during measurements. The setup is a combination of a vectorial MOKE bench and a cryostat with optical access. The cryostat has a motorized rotatable sample holder with azimuthal correction. It allows for simultaneous and quantitative acquisition of the two in-plane magnetization components during the hysteresis loop at different temperatures from 4 K up to 500 K and in the whole angular range, without neither changing magnet orientation nor opening the cryostat. Measurements performed in a model system with competing collinear biaxial and uniaxial contributions are presented to illustrate its capabilities.

  9. Investigation of nitric oxide decomposition in the temperature range 2500-4100 K

    NASA Technical Reports Server (NTRS)

    Flower, W. L.; Hanson, R. K.; Kruger, C. H.

    1974-01-01

    The decomposition of nitric oxide has been studied in the temperature range 2500-4100 K using a shock-tube technique. The principle result of the study was the determination of the rate constant (k) for the reaction O + NO yields N + O2. Mixtures of NO and N2O diluted in argon or krypton were heated by incident shock waves and the infrared emission from the fundamental vibration-rotation band of NO at 5.3 microns was used to monitor the time-varying NO concentration. The experimental values of k are fit closely by the expression k = (2.36 times 10 to the 9th power) x T x exp(-38,640/RT) cm cu/mole-sec, which also provides a good fit to previous data at higher and lower temperatures.

  10. Quantifying of uncertainty range of regional temperature change due to global warming using RCM

    NASA Astrophysics Data System (ADS)

    Ishihara, K.; Takayabu, I.

    2010-12-01

    It is important to accurately assess future change in various risk due to global warming, for which regional projections have been made using high-resolution climate models. The project “Multi-method Included Downscaling for Assessment Study” which is the part of S-5 project (Integrated Research on Climate Change Scenarios to Increase Public Awareness) sponsored by the Ministry of Environment, Japan, is one of the downscaling projects in Japan. In this project, we down-scale the GCM’s result in two steps, which are (1) to reduce the uncertainty of the dynamical downscaling result, and (2) to derive information for use in impact studies. This presentation introduces both the brief overview of the project (S-5-3) and the estimated uncertainty range of annual temperature change in each prefecture in Japan. The uncertainty range was estimated using the normality of appearance frequency of annual temperature both for the present and future climates. A regional climate model with a resolution of 20km (MRI-RCM20) was used in the study, and SRES A2 scenario was used for the future climate. As a result, for example, annual temperature around the northern part of Hokkaido was projected to rise by 3.2±1.7 degrees in 100 years. Now, for the verification of RCMs, their results are often compared with the observed data of each meteorological element such as temperature in each region. This means that the reproducibility of the RCM is quantified for each element in each region. However, for overall verification of the RCM, it is necessary to develop a statistical method such as CCA which can deal with some elements over regions. This work was supported by the Global Environment Research Fund (S-5-3) of the Ministry of the Environment, Japan.

  11. A new method for achieving enhanced dielectric response over a wide temperature range

    SciTech Connect

    Maurya, Deepam; Sun, Fu -Chang; Pamir Alpay, S.; Priya, Shashank

    2015-10-19

    We report a novel approach for achieving high dielectric response over a wide temperature range. In this approach, multilayer ceramic heterostructures with constituent compositions having strategically tuned Curie points (TC) were designed and integrated with varying electrical connectivity. Interestingly, these multilayer structures exhibited different dielectric behavior in series and parallel configuration due to variations in electrical boundary conditions resulting in the differences in the strength of the electrostatic coupling. The results are explained using nonlinear thermodynamic model taking into account electrostatic interlayer interaction. We believe that present work will have huge significance in design of high performance ceramic capacitors.

  12. Oxidation characteristics of Beta-21S in air in the temperature range 600 to 800 C

    NASA Technical Reports Server (NTRS)

    Wallace, Terryl A.; Clark, Ronald K.; Wiedemann, Karl E.

    1992-01-01

    The metastable beta-Ti alloy Beta-21S, Ti-15Mo-2.7Nb-3Al-0.2Si (weight percent), has been proposed as a candidate for use in metal matrix composites in future hypersonic vehicles. The present study investigated the oxidation behavior of Beta-21S over the temperature range 600 C to 800 C. Oxidation weight gain was evaluated using thermogravimetric analysis. Oxidized specimens were evaluated using x ray diffraction techniques, scanning electron microscopy, energy dispersive x ray analysis, and electron microprobe analysis to identify oxidation products and evaluate oxidation damage to the alloy.

  13. Traceable Thermoelectric Measurements of Seebeck Coefficients in the Temperature Range from 300 K to 900 K

    NASA Astrophysics Data System (ADS)

    Lenz, Ernst; Edler, Frank; Ziolkowski, Pawel

    2013-10-01

    This work is focused on the characterization of thermoelectric reference materials with traceable Seebeck coefficients in the temperature range from 300 K to 900 K. The presented measurement system will provide a relative uncertainty of the measurement of the Seebeck coefficient of about 5 %. The Seebeck coefficient represents an important component of the figure of merit ZT and thus the low uncertainty of the Seebeck coefficient will also lower the uncertainty of the ZT value. We also present data which lead to the launch of the certification process of a NiCu-alloy according to the ISO Guide 35.

  14. A new method for achieving enhanced dielectric response over a wide temperature range

    PubMed Central

    Maurya, Deepam; Sun, Fu-Chang; Pamir Alpay, S.; Priya, Shashank

    2015-01-01

    We report a novel approach for achieving high dielectric response over a wide temperature range. In this approach, multilayer ceramic heterostructures with constituent compositions having strategically tuned Curie points (TC) were designed and integrated with varying electrical connectivity. Interestingly, these multilayer structures exhibited different dielectric behavior in series and parallel configuration due to variations in electrical boundary conditions resulting in the differences in the strength of the electrostatic coupling. The results are explained using nonlinear thermodynamic model taking into account electrostatic interlayer interaction. We believe that present work will have huge significance in design of high performance ceramic capacitors. PMID:26477391

  15. The absorption of sulfur dioxide in the terahertz range at temperatures of 300-1200 K

    NASA Astrophysics Data System (ADS)

    Voitsekhovskaya, O. K.; Egorov, O. V.

    2013-03-01

    The rotational spectrum of the absorption of the main isotope of sulfur dioxide (32S16O2), which corresponds to the terahertz range of electromagnetic waves, namely 1-250 cm-1 (0.1-10 THz), is studied. The consideration covers rotational transitions within all vibrational states whose Hamiltonian parameters are known from the literature: (000-000), (010-010), (100-100), (001-001), (020-020), (110-110), (011-011), (030-030), (120-120), (200-200), (002-002), (130-130), (103-103), (301-301), (101-101), (021-021), (210-210), (111-111), (201-201), (003-003), and (131-131). As a result, the absorption coefficient of 32S16O2 is calculated for a broad temperature range (300-1200 K) and the contribution of the rotational band of each vibrational state to the total absorption coefficient is evaluated.

  16. Low temperature pyrotechnic smokes: A potential low cost alternative to nonpyrotechnic smoke for access delay applications

    SciTech Connect

    Greenholt, C.J.

    1995-07-01

    Smokes are frequently used as visual obscurants in access delay applications. A new generation of low temperature pyrotechnic smokes is being developed. Terephthalic Acid (TPA) smoke was developed by the U.S. Army and Sebacic Acid (SA) smoke is being developed by Thiokol Corp. The advantages these smokes offer over traditional pyrotechnic smokes include; low generation temperature (approximately 450{degree}C), lower toxicity, and lower corrosivity. The low generation temperature reduces smoke layering effects and allows the addition of sensory irritants, such as o-Chlorobenzylidene Malononitrile (CS), to the formulation. Some advantages low temperature pyrotechnic smokes offer over nonpyrotechnic smokes include; low cost, simplicity, compactness, light weight, long storage life, and orientation insensitive operation. Low cost permits distribution of multiple units for reduced vulnerability and refill flexibility. Some disadvantages may include the combustibility of the smoke particulate; however, the published lower explosive limit of the mentioned materials is approximately ten times greater than the concentration required for effective obscuration. The TPA smoke cloud contains small quantities of benzene, formaldehyde, and carbon monoxide; no benzene or formaldehyde was identified during preliminary SA smoke analyses performed by Thiokol Corp. Sandia performed tests and analyses on TPA smoke to determine the smoke cloud composition, the quantity of particulate produced per canister, and the relationship between airborne particulate concentration and measured optical density values. Current activities include characterization of SA smoke.

  17. Long-range cross-correlation between urban impervious surfaces and land surface temperatures

    NASA Astrophysics Data System (ADS)

    Nie, Qin; Xu, Jianhua; Man, Wang

    2016-03-01

    The thermal effect of urban impervious surfaces (UIS) is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures (LST) using complexity science theory and methods. This paper investigates the long-range cross-correlation between UIS and LST with detrended cross-correlation analysis and multifractal detrended cross-correlation analysis, utilizing data from downtown Shanghai, China. UIS estimates were obtained from linear spectral mixture analysis, and LST was retrieved through application of the mono-window algorithm, using Landsat Thematic Mapper and Enhanced Thematic Mapper Plus data for 1997-2010. These results highlight a positive long-range cross-correlation between UIS and LST across People's Square in Shanghai. LST has a long memory for a certain spatial range of UIS values, such that a large increment in UIS is likely to be followed by a large increment in LST. While the multifractal long-range cross-correlation between UIS and LST was observed over a longer time period in the W-E direction (2002-2010) than in the N-S (2007-2010), these observed correlations show a weakening during the study period as urbanization increased.

  18. Retrieval and Mapping of Soil Texture Based on Land Surface Diurnal Temperature Range Data from MODIS.

    PubMed

    Wang, De-Cai; Zhang, Gan-Lin; Zhao, Ming-Song; Pan, Xian-Zhang; Zhao, Yu-Guo; Li, De-Cheng; Macmillan, Bob

    2015-01-01

    Numerous studies have investigated the direct retrieval of soil properties, including soil texture, using remotely sensed images. However, few have considered how soil properties influence dynamic changes in remote images or how soil processes affect the characteristics of the spectrum. This study investigated a new method for mapping regional soil texture based on the hypothesis that the rate of change of land surface temperature is related to soil texture, given the assumption of similar starting soil moisture conditions. The study area was a typical flat area in the Yangtze-Huai River Plain, East China. We used the widely available land surface temperature product of MODIS as the main data source. We analyzed the relationships between the content of different particle soil size fractions at the soil surface and land surface day temperature, night temperature and diurnal temperature range (DTR) during three selected time periods. These periods occurred after rainfalls and between the previous harvest and the subsequent autumn sowing in 2004, 2007 and 2008. Then, linear regression models were developed between the land surface DTR and sand (> 0.05 mm), clay (< 0.001 mm) and physical clay (< 0.01 mm) contents. The models for each day were used to estimate soil texture. The spatial distribution of soil texture from the studied area was mapped based on the model with the minimum RMSE. A validation dataset produced error estimates for the predicted maps of sand, clay and physical clay, expressed as RMSE of 10.69%, 4.57%, and 12.99%, respectively. The absolute error of the predictions is largely influenced by variations in land cover. Additionally, the maps produced by the models illustrate the natural spatial continuity of soil texture. This study demonstrates the potential for digitally mapping regional soil texture variations in flat areas using readily available MODIS data. PMID:26090852

  19. Liquid state DNP for water accessibility measurements on spin-labeled membrane proteins at physiological temperatures.

    PubMed

    Doll, Andrin; Bordignon, Enrica; Joseph, Benesh; Tschaggelar, René; Jeschke, Gunnar

    2012-09-01

    We demonstrate the application of continuous wave dynamic nuclear polarization (DNP) at 0.35 T for site-specific water accessibility studies on spin-labeled membrane proteins at concentrations in the 10-100 μM range. The DNP effects at such low concentrations are weak and the experimentally achievable dynamic nuclear polarizations can be below the equilibrium polarization. This sensitivity problem is solved with an optimized home-built DNP probe head consisting of a dielectric microwave resonator and a saddle coil as close as possible to the sample. The performance of the probe head is demonstrated with both a modified pulsed EPR spectrometer and a dedicated CW EPR spectrometer equipped with a commercial NMR console. In comparison to a commercial pulsed ENDOR resonator, the home-built resonator has an FID detection sensitivity improvement of 2.15 and an electron spin excitation field improvement of 1.2. The reproducibility of the DNP results is tested on the water soluble maltose binding protein MalE of the ABC maltose importer, where we determine a net standard deviation of 9% in the primary DNP data in the concentration range between 10 and 100 μM. DNP parameters are measured in a spin-labeled membrane protein, namely the vitamin B(12) importer BtuCD in both detergent-solubilized and reconstituted states. The data obtained in different nucleotide states in the presence and absence of binding protein BtuF reveal the applicability of this technique to qualitatively extract water accessibility changes between different conformations by the ratio of primary DNP parameters ϵ. The ϵ-ratio unveils the physiologically relevant transmembrane communication in the transporter in terms of changes in water accessibility at the cytoplasmic gate of the protein induced by both BtuF binding at the periplasmic region of the transporter and ATP binding at the cytoplasmic nucleotide binding domains.

  20. Liquid state DNP for water accessibility measurements on spin-labeled membrane proteins at physiological temperatures

    NASA Astrophysics Data System (ADS)

    Doll, Andrin; Bordignon, Enrica; Joseph, Benesh; Tschaggelar, René; Jeschke, Gunnar

    2012-09-01

    We demonstrate the application of continuous wave dynamic nuclear polarization (DNP) at 0.35 T for site-specific water accessibility studies on spin-labeled membrane proteins at concentrations in the 10-100 μM range. The DNP effects at such low concentrations are weak and the experimentally achievable dynamic nuclear polarizations can be below the equilibrium polarization. This sensitivity problem is solved with an optimized home-built DNP probe head consisting of a dielectric microwave resonator and a saddle coil as close as possible to the sample. The performance of the probe head is demonstrated with both a modified pulsed EPR spectrometer and a dedicated CW EPR spectrometer equipped with a commercial NMR console. In comparison to a commercial pulsed ENDOR resonator, the home-built resonator has an FID detection sensitivity improvement of 2.15 and an electron spin excitation field improvement of 1.2. The reproducibility of the DNP results is tested on the water soluble maltose binding protein MalE of the ABC maltose importer, where we determine a net standard deviation of 9% in the primary DNP data in the concentration range between 10 and 100 μM. DNP parameters are measured in a spin-labeled membrane protein, namely the vitamin B12 importer BtuCD in both detergent-solubilized and reconstituted states. The data obtained in different nucleotide states in the presence and absence of binding protein BtuF reveal the applicability of this technique to qualitatively extract water accessibility changes between different conformations by the ratio of primary DNP parameters ɛ. The ɛ-ratio unveils the physiologically relevant transmembrane communication in the transporter in terms of changes in water accessibility at the cytoplasmic gate of the protein induced by both BtuF binding at the periplasmic region of the transporter and ATP binding at the cytoplasmic nucleotide binding domains.

  1. Effects of diurnal temperature range and drought on wheat yield in Spain

    NASA Astrophysics Data System (ADS)

    Hernandez-Barrera, S.; Rodriguez-Puebla, C.; Challinor, A. J.

    2016-04-01

    This study aims to provide new insight on the wheat yield historical response to climate processes throughout Spain by using statistical methods. Our data includes observed wheat yield, pseudo-observations E-OBS for the period 1979 to 2014, and outputs of general circulation models in phase 5 of the Coupled Models Inter-comparison Project (CMIP5) for the period 1901 to 2099. In investigating the relationship between climate and wheat variability, we have applied the approach known as the partial least-square regression, which captures the relevant climate drivers accounting for variations in wheat yield. We found that drought occurring in autumn and spring and the diurnal range of temperature experienced during the winter are major processes to characterize the wheat yield variability in Spain. These observable climate processes are used for an empirical model that is utilized in assessing the wheat yield trends in Spain under different climate conditions. To isolate the trend within the wheat time series, we implemented the adaptive approach known as Ensemble Empirical Mode Decomposition. Wheat yields in the twenty-first century are experiencing a downward trend that we claim is a consequence of widespread drought over the Iberian Peninsula and an increase in the diurnal range of temperature. These results are important to inform about the wheat vulnerability in this region to coming changes and to develop adaptation strategies.

  2. Gas-Phase Reaction of Hydroxyl Radical with p-Cymene over an Extended Temperature Range.

    PubMed

    Bedjanian, Yuri; Morin, Julien; Romanias, Manolis N

    2015-11-12

    The kinetics of the reaction of OH radicals with p-cymene has been studied in the temperature range of 243-898 K using a flow reactor combined with a quadrupole mass spectrometer: OH + p-cymene → products. The reaction rate constant was determined as a result of absolute measurements, from OH decay kinetics in excess of p-cymene and employing the relative rate method with OH reactions with n-pentane, n-heptane,1,3-dioxane, HBr, and Br2 as the reference ones. For the rate coefficient of the H atom abstraction channel, the expression k1b = (3.70 ± 0.42) × 10(-11) exp[-(772 ± 72)/T] was obtained over the temperature range of 381-898 K. The total rate constant (addition + abstraction) determined at T = 243-320 K was k1 = (1.82 ± 0.48) × 10(-12) exp[(607 ± 70)/T] or, in a biexponential form, k1 = k1a + k1b = 3.7 × 10(-11) exp(-772/T) + 6.3 × 10(-13) exp(856/T), independent of the pressure between 1 and 5 Torr of helium. In addition, our results indicate that the reaction pathway involving alkyl radical elimination upon initial addition of OH to p-cymene is most probably unimportant. PMID:26473634

  3. Using Diurnal Temperature Range to Examine the Climatology of Solar Energy Potential

    NASA Astrophysics Data System (ADS)

    Zercher, C. N.; Hanrahan, J.; Murphy, S. Y.

    2015-12-01

    The potential for annual solar energy production largely depends on the amount of incoming shortwave radiation which is dependent on cloud cover. Due to natural large-scale climate variability, long-term cloud cover can vary substantially, therefore modifying the total energy that can be produced by solar cells in individual locations. Under anthropogenic climate change, future precipitation is expected to significantly deviate from observed values, therefore suggesting that cloud cover, and thus solar energy potential, will also change. The expected changes are both positive and negative depending on geographic region and can be highly spatially variable, particularly in regions of complex terrain. Because of the short-term availability of observed radiation and cloud cover data, it is difficult to study the historical climatology of solar energy potential, thus making future projections uncertain. Research has shown that another readily available climate variable, the diurnal temperature range, correlates well with daily averaged shortwave radiation values during months of minimal/no snow cover, and can thus serve as a proxy for shortwave radiation during the warm season throughout the period of record. In the present study, the diurnal temperature range is shown to be an excellent predictor of shortwave radiation around the state of Vermont, independent of latitude and elevation. Monte Carlo significance testing is also used to examine recent trends in this region.

  4. Gas-Phase Reaction of Hydroxyl Radical with p-Cymene over an Extended Temperature Range.

    PubMed

    Bedjanian, Yuri; Morin, Julien; Romanias, Manolis N

    2015-11-12

    The kinetics of the reaction of OH radicals with p-cymene has been studied in the temperature range of 243-898 K using a flow reactor combined with a quadrupole mass spectrometer: OH + p-cymene → products. The reaction rate constant was determined as a result of absolute measurements, from OH decay kinetics in excess of p-cymene and employing the relative rate method with OH reactions with n-pentane, n-heptane,1,3-dioxane, HBr, and Br2 as the reference ones. For the rate coefficient of the H atom abstraction channel, the expression k1b = (3.70 ± 0.42) × 10(-11) exp[-(772 ± 72)/T] was obtained over the temperature range of 381-898 K. The total rate constant (addition + abstraction) determined at T = 243-320 K was k1 = (1.82 ± 0.48) × 10(-12) exp[(607 ± 70)/T] or, in a biexponential form, k1 = k1a + k1b = 3.7 × 10(-11) exp(-772/T) + 6.3 × 10(-13) exp(856/T), independent of the pressure between 1 and 5 Torr of helium. In addition, our results indicate that the reaction pathway involving alkyl radical elimination upon initial addition of OH to p-cymene is most probably unimportant.

  5. The creation of high-temperature superconducting cables of megawatt range in Russia

    NASA Astrophysics Data System (ADS)

    Sytnikov, V. E.; Bemert, S. E.; Krivetsky, I. V.; Romashov, M. A.; Popov, D. A.; Fedotov, E. V.; Komandenko, O. V.

    2015-12-01

    Urgent problems of the power industry in the 21st century require the creation of smart energy systems, providing a high effectiveness of generation, transmission, and consumption of electric power. Simultaneously, the requirements for controllability of power systems and ecological and resource-saving characteristics at all stages of production and distribution of electric power are increased. One of the decision methods of many problems of the power industry is the development of new high-efficiency electrical equipment for smart power systems based on superconducting technologies to ensure a qualitatively new level of functioning of the electric power industry. The intensive research and development of new types of electrical devices based on superconductors are being carried out in many industrialized advanced countries. Interest in such developments has especially increased in recent years owing to the discovery of so-called high-temperature superconductors (HTS) that do not require complicated and expensive cooling devices. Such devices can operate at cooling by inexpensive and easily accessible liquid nitrogen. Taking into account the obvious advantages of superconducting cable lines for the transmission of large power flows through an electrical network, as compared with conventional cables, the Federal Grid Company of Unified Energy System (JSC FGC UES) initiated a research and development program including the creation of superconducting HTS AC and DC cable lines. Two cable lines for the transmitted power of 50 MVA/MW at 20 kV were manufactured and tested within the framework of the program.

  6. The creation of high-temperature superconducting cables of megawatt range in Russia

    SciTech Connect

    Sytnikov, V. E. Bemert, S. E.; Krivetsky, I. V.; Romashov, M. A.; Popov, D. A.; Fedotov, E. V.; Komandenko, O. V.

    2015-12-15

    Urgent problems of the power industry in the 21st century require the creation of smart energy systems, providing a high effectiveness of generation, transmission, and consumption of electric power. Simultaneously, the requirements for controllability of power systems and ecological and resource-saving characteristics at all stages of production and distribution of electric power are increased. One of the decision methods of many problems of the power industry is the development of new high-efficiency electrical equipment for smart power systems based on superconducting technologies to ensure a qualitatively new level of functioning of the electric power industry. The intensive research and development of new types of electrical devices based on superconductors are being carried out in many industrialized advanced countries. Interest in such developments has especially increased in recent years owing to the discovery of so-called high-temperature superconductors (HTS) that do not require complicated and expensive cooling devices. Such devices can operate at cooling by inexpensive and easily accessible liquid nitrogen. Taking into account the obvious advantages of superconducting cable lines for the transmission of large power flows through an electrical network, as compared with conventional cables, the Federal Grid Company of Unified Energy System (JSC FGC UES) initiated a research and development program including the creation of superconducting HTS AC and DC cable lines. Two cable lines for the transmitted power of 50 MVA/MW at 20 kV were manufactured and tested within the framework of the program.

  7. Ductile long range ordered alloys with high critical ordering temperature and wrought articles fabricated therefrom

    DOEpatents

    Liu, Chain T.; Inouye, Henry

    1979-01-01

    Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Fe, Co).sub.3 and V(Fe, Co, Ni).sub.3 systems. These alloys have the following compositions comprising by weight: 22-23% V, 14-30% Fe, and the remainder Co or Co and Ni with an electron density no more than 7.85. The maximum combination of high temperature strength, ductility and creep resistance are manifested in the alloy comprising by weight 22-23% V, 14-20% Fe and the remainder Co and having an atomic composition of V(Fe .sub.0.20-0.26 C Co.sub.0.74-0.80).sub.3. The alloy comprising by weight 22-23% V, 16-17% Fe and 60-62% Co has excellent high temperature properties. The alloys are fabricable into wrought articles by casting, deforming, and annealing for sufficient time to provide ordered structure.

  8. Magnetic Properties of the Stack of HTSC Tapes in a Wide Temperature Range

    NASA Astrophysics Data System (ADS)

    Rudnev, Igor; Abin, Dmitriy; Osipov, Maxim; Pokrovskiy, Sergey; Ermolaev, Yuriy; Mineev, Nikolay

    The trapped field strength of HTSC stacks were measured in the temperature range T=4-80 K and dc magnetic fields up to 8 Т. A single 12 mm by 12 mm square samples were cut from commercial (RE)BCO tape 12 mm wide and then stacked together. The number of layers in the stacks was varied from n=5 to n=250. Trapped field strength was measured by means of Hall probe which was placed directly on the stacks surface. The dependences of remnant field strength Brem on number of layers in the stacks at different temperature Brem (n) as well as on temperature dependences Brem (T) at various n were obtained. It was found that Brem (n) dependences have a nonlinear character with a tendency to saturation for n > 60. The maximum remnant (trapped) field was found to be more than 2.5 Т at T=4 К. The relaxation of trapped field was studied also and it was determined that the rate of relaxation processes tends to decrease with the increase in a number of tapes in the stack. The correlation between dependency Brem (n) and dependency of magnetic levitation force measured at T=77 K at zero field cooling were found.

  9. Performance of MEMS Silicon Oscillator, ASFLM1, under Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2008-01-01

    Over the last few years, MEMS (Micro-Electro-Mechanical Systems) resonator-based oscillators began to be offered as commercial-off-the-shelf (COTS) parts by a few companies [1-2]. These quartz-free, miniature silicon devices could compete with the traditional crystal oscillators in providing the timing (clock function) for many digital and analog electronic circuits. They provide stable output frequency, offer great tolerance to shock and vibration, and are immune to electro-static discharge [1-2]. In addition, they are encapsulated in compact lead-free packages, cover a wide frequency range (1 MHz to 125 MHz), and are specified, depending on the grade, for extended temperature operation from -40 C to +85 C. The small size of the MEMS oscillators along with their reliability and thermal stability make them candidates for use in space exploration missions. Limited data, however, exist on the performance and reliability of these devices under operation in applications where extreme temperatures or thermal cycling swings, which are typical of space missions, are encountered. This report presents the results of the work obtained on the evaluation of an ABRACON Corporation MEMS silicon oscillator chip, type ASFLM1, under extreme temperatures.

  10. Long-range persistence in the global mean surface temperature and the global warming "time bomb"

    NASA Astrophysics Data System (ADS)

    Rypdal, M.; Rypdal, K.

    2012-04-01

    Detrended Fluctuation Analysis (DFA) and Maximum Likelihood Estimations (MLE) based on instrumental data over the last 160 years indicate that there is Long-Range Persistence (LRP) in Global Mean Surface Temperature (GMST) on time scales of months to decades. The persistence is much higher in sea surface temperature than in land temperatures. Power spectral analysis of multi-model, multi-ensemble runs of global climate models indicate further that this persistence may extend to centennial and maybe even millennial time-scales. We also support these conclusions by wavelet variogram analysis, DFA, and MLE of Northern hemisphere mean surface temperature reconstructions over the last two millennia. These analyses indicate that the GMST is a strongly persistent noise with Hurst exponent H>0.9 on time scales from decades up to at least 500 years. We show that such LRP can be very important for long-term climate prediction and for the establishment of a "time bomb" in the climate system due to a growing energy imbalance caused by the slow relaxation to radiative equilibrium under rising anthropogenic forcing. We do this by the construction of a multi-parameter dynamic-stochastic model for the GMST response to deterministic and stochastic forcing, where LRP is represented by a power-law response function. Reconstructed data for total forcing and GMST over the last millennium are used with this model to estimate trend coefficients and Hurst exponent for the GMST on multi-century time scale by means of MLE. Ensembles of solutions generated from the stochastic model also allow us to estimate confidence intervals for these estimates.

  11. Evidence of both phenological and range shifts in birds in response to increasing temperature in Ireland

    NASA Astrophysics Data System (ADS)

    Donnelly, Alison; Cooney, Tom; Stirnemann, Rebecca; O'Halloran, John

    2010-05-01

    It is well established that the timing of arrival of long-distance migrant birds in spring is advancing throughout Europe and that this response is, at least in part, due to an increase in temperature in line with current global warming. In Ireland, we have seen a number of sub-Saharan species, such as, barn swallow (Hirundo rustica), northern wheatear (Oenanthe oenanthe) and sand martin (Riparia riparia) advance their arrival time over a 31-year period. In addition, a medium-distance winter migrant, the whooper swan (Cygnus cygnus), has significantly advanced its spring departure time from its wintering ground in Ireland. Furthermore, a number of species, such as the little egret (Egretta garzetta), more typically associated with a warmer climate than Ireland, was considered to be a ‘rare visitor' up to 1990 and has now begun to breed and to establish a population on the island. All of these phenological and range shifts have been correlated with various temperature variables. The consequences of early arrival at wintering and breeding grounds could result in increased fitness but only if an appropriate food resource is in adequate supply at the new earlier time. If temperatures continue to rise as predicted, the status of some bird species in Ireland may change from ‘rare' to ‘common' or from ‘visitor' to ‘resident' with a possible concurrent increase in population size. Equally, the opposite trend may occur, for birds that prefer cold temperatures, whereby we may see a decrease in population size followed by the loss of certain species.

  12. Neutral temperature range in incubators: performance of equipment in current use and new developments.

    PubMed

    Libert, J P; Bach, V; Farges, G

    1997-01-01

    Low-birth-weight neonates should be nursed at thermoneutrality inside incubators. Thermoneutrality control is essential to enhance body growth and to reduce neonatal illnesses and mortality. Guidelines have been published to provide the thermoneutral range, but the recommendations did not always take into account all ambient and physiological parameters influencing thermoneutrality. In most marketed incubators, the heat supply is controlled through convective air flow (closed incubators) or through radiant power density (radiant warmer beds). The heating unit (on/off cycling or adjustable proportional control) is activated by an error signal calculated from the difference between a controlled temperature and a reference value preset by the clinician. The controlled variable can be either the incubator air or the skin temperature of the anterior abdominal region of the neonate. The neonate's size, thermal properties of the mattress and of incubator walls, air temperature and humidity, air velocity, incubator wall temperatures all influence the heat exchanges between the neonate and the surroundings, and, consequently, modify the obtention of thermoneutrality. Moreover, studies of the physiological mechanisms by which the neonate regulates body heat storage suggest that metabolic rate, behavior, vigilance level, nursing care, and heater control processes should also be taken into account. Little attention has been paid to these factors, and incubator performances are often disappointing. This article reviews the different factors that modify thermoneutral condition. An attempt is made to suggest new ways to design equipment incorporating these factors in algorithms controlling heater processes in order to reach the optimal thermal environment in which the neonate should be nursed.

  13. A Polynucleotide Repeat Expansion Causing Temperature-Sensitivity Persists in Wild Irish Accessions of Arabidopsis thaliana

    PubMed Central

    Tabib, Amanda; Vishwanathan, Sailaja; Seleznev, Andrei; McKeown, Peter C.; Downing, Tim; Dent, Craig; Sanchez-Bermejo, Eduardo; Colling, Luana; Spillane, Charles; Balasubramanian, Sureshkumar

    2016-01-01

    Triplet repeat expansions underlie several human genetic diseases such as Huntington's disease and Friedreich's ataxia. Although such mutations are primarily known from humans, a triplet expansion associated genetic defect has also been reported at the IIL1 locus in the Bur-0 accession of the model plant Arabidopsis thaliana. The IIL1 triplet expansion is an example of cryptic genetic variation as its phenotypic effects are seen only under genetic or environmental perturbation, with high temperatures resulting in a growth defect. Here we demonstrate that the IIL1 triplet expansion associated growth defect is not a general stress response and is specific to particular environmental perturbations. We also confirm and map genetic modifiers that suppress the effect of IIL1 triplet repeat expansion. By collecting and analyzing accessions from the island of Ireland, we recover the repeat expansion in wild populations suggesting that the repeat expansion has persisted at least 60 years in Ireland. Through genome-wide genotyping, we show that the repeat expansion is present in diverse Irish populations. Our findings indicate that even deleterious alleles can persist in populations if their effect is conditional. Our study demonstrates that analysis of groups of wild populations is a powerful tool for understanding the dynamics of cryptic genetic variation.

  14. A Polynucleotide Repeat Expansion Causing Temperature-Sensitivity Persists in Wild Irish Accessions of Arabidopsis thaliana.

    PubMed

    Tabib, Amanda; Vishwanathan, Sailaja; Seleznev, Andrei; McKeown, Peter C; Downing, Tim; Dent, Craig; Sanchez-Bermejo, Eduardo; Colling, Luana; Spillane, Charles; Balasubramanian, Sureshkumar

    2016-01-01

    Triplet repeat expansions underlie several human genetic diseases such as Huntington's disease and Friedreich's ataxia. Although such mutations are primarily known from humans, a triplet expansion associated genetic defect has also been reported at the IIL1 locus in the Bur-0 accession of the model plant Arabidopsis thaliana. The IIL1 triplet expansion is an example of cryptic genetic variation as its phenotypic effects are seen only under genetic or environmental perturbation, with high temperatures resulting in a growth defect. Here we demonstrate that the IIL1 triplet expansion associated growth defect is not a general stress response and is specific to particular environmental perturbations. We also confirm and map genetic modifiers that suppress the effect of IIL1 triplet repeat expansion. By collecting and analyzing accessions from the island of Ireland, we recover the repeat expansion in wild populations suggesting that the repeat expansion has persisted at least 60 years in Ireland. Through genome-wide genotyping, we show that the repeat expansion is present in diverse Irish populations. Our findings indicate that even deleterious alleles can persist in populations if their effect is conditional. Our study demonstrates that analysis of groups of wild populations is a powerful tool for understanding the dynamics of cryptic genetic variation. PMID:27630650

  15. A Polynucleotide Repeat Expansion Causing Temperature-Sensitivity Persists in Wild Irish Accessions of Arabidopsis thaliana

    PubMed Central

    Tabib, Amanda; Vishwanathan, Sailaja; Seleznev, Andrei; McKeown, Peter C.; Downing, Tim; Dent, Craig; Sanchez-Bermejo, Eduardo; Colling, Luana; Spillane, Charles; Balasubramanian, Sureshkumar

    2016-01-01

    Triplet repeat expansions underlie several human genetic diseases such as Huntington's disease and Friedreich's ataxia. Although such mutations are primarily known from humans, a triplet expansion associated genetic defect has also been reported at the IIL1 locus in the Bur-0 accession of the model plant Arabidopsis thaliana. The IIL1 triplet expansion is an example of cryptic genetic variation as its phenotypic effects are seen only under genetic or environmental perturbation, with high temperatures resulting in a growth defect. Here we demonstrate that the IIL1 triplet expansion associated growth defect is not a general stress response and is specific to particular environmental perturbations. We also confirm and map genetic modifiers that suppress the effect of IIL1 triplet repeat expansion. By collecting and analyzing accessions from the island of Ireland, we recover the repeat expansion in wild populations suggesting that the repeat expansion has persisted at least 60 years in Ireland. Through genome-wide genotyping, we show that the repeat expansion is present in diverse Irish populations. Our findings indicate that even deleterious alleles can persist in populations if their effect is conditional. Our study demonstrates that analysis of groups of wild populations is a powerful tool for understanding the dynamics of cryptic genetic variation. PMID:27630650

  16. A Polynucleotide Repeat Expansion Causing Temperature-Sensitivity Persists in Wild Irish Accessions of Arabidopsis thaliana.

    PubMed

    Tabib, Amanda; Vishwanathan, Sailaja; Seleznev, Andrei; McKeown, Peter C; Downing, Tim; Dent, Craig; Sanchez-Bermejo, Eduardo; Colling, Luana; Spillane, Charles; Balasubramanian, Sureshkumar

    2016-01-01

    Triplet repeat expansions underlie several human genetic diseases such as Huntington's disease and Friedreich's ataxia. Although such mutations are primarily known from humans, a triplet expansion associated genetic defect has also been reported at the IIL1 locus in the Bur-0 accession of the model plant Arabidopsis thaliana. The IIL1 triplet expansion is an example of cryptic genetic variation as its phenotypic effects are seen only under genetic or environmental perturbation, with high temperatures resulting in a growth defect. Here we demonstrate that the IIL1 triplet expansion associated growth defect is not a general stress response and is specific to particular environmental perturbations. We also confirm and map genetic modifiers that suppress the effect of IIL1 triplet repeat expansion. By collecting and analyzing accessions from the island of Ireland, we recover the repeat expansion in wild populations suggesting that the repeat expansion has persisted at least 60 years in Ireland. Through genome-wide genotyping, we show that the repeat expansion is present in diverse Irish populations. Our findings indicate that even deleterious alleles can persist in populations if their effect is conditional. Our study demonstrates that analysis of groups of wild populations is a powerful tool for understanding the dynamics of cryptic genetic variation.

  17. Effect of glass composition on activation energy of viscosity in glass-melting-temperature range

    SciTech Connect

    Hrma, Pavel R.; Han, Sang Soo

    2012-08-01

    In the high-temperature range, where the viscosity (Eta) of molten glass is <10{sup 3} Pa s, the activation energy (B) is virtually ln(Eta) = A + B/T, is nearly independent of melt composition. Hence, the viscosity-composition relationship for Eta < 10{sup 3} Pa s is defined by B as a function of composition. Using a database encompassing over 1300 compositions of high-level waste glasses with nearly 7000 viscosity data, we developed mathematical models for B(x), where x is the composition vector in terms of mass fractions of components. In this paper, we present 13 versions of B(x) as first- and second-order polynomials with coefficients for 15 to 39 components, including Others, a component that sums constituents having little effect on viscosity.

  18. Radiative Vaporization of Graphite in the Temperature Range of 4000 to 4500 deg K

    NASA Technical Reports Server (NTRS)

    Lundell, John H.; Dickey, Robert R.

    1976-01-01

    The vaporization of graphite under intense laser radiation is considered both theoretically and experimentally. Under intense radiation, the mass-loss rate can be high enough to cause the flow in the laser plume to be supersonic. Under these conditions, the vaporization process is coupled to the plume gasdynamics. Experimental results are presented for surface temperatures of 3985 to 4555 K and mass-loss rates from 0.52 to 27.0 g/sq cm sec. The data are used to determine the vapor pressure of graphite in a range of 2 to 11 atm, and the results are shown to be in good agreement with the JANAF vapor pressure curve, if the vaporization coefficients are unity. The assumption of unity vaporization coefficients is shown to be reasonable by a comparison of the present results with other recent vapor pressure results for graphite.

  19. Vaporization of graphite in the temperature range of 4000 to 4500 K

    NASA Technical Reports Server (NTRS)

    Lundell, J. H.; Dickey, R. R.

    1976-01-01

    The vaporization of graphite under intense laser radiation is considered both theoretically and experimentally. Under intense radiation, the mass-loss rate can be high enough to cause the flow in the laser plume to be supersonic. It is shown that under these conditions the vaporization process is coupled to the plume gasdynamics and the mass-loss rate for graphite is 62% of the free vaporization rate. Experimental results are presented for surface temperatures from 3985 to 4555 K and mass-loss rates from 0.56 to 27.0 g per sq cm sec. The results are used to determine the vapor pressure of graphite in a pressure range of 2 to 11 atm, and the values are shown to be in agreement with the JANAF vapor pressure curve.

  20. Methane storage in nanoporous material at supercritical temperature over a wide range of pressures

    NASA Astrophysics Data System (ADS)

    Wu, Keliu; Chen, Zhangxin; Li, Xiangfang; Dong, Xiaohu

    2016-09-01

    The methane storage behavior in nanoporous material is significantly different from that of a bulk phase, and has a fundamental role in methane extraction from shale and its storage for vehicular applications. Here we show that the behavior and mechanisms of the methane storage are mainly dominated by the ratio of the interaction between methane molecules and nanopores walls to the methane intermolecular interaction, and a geometric constraint. By linking the macroscopic properties of the methane storage to the microscopic properties of a system of methane molecules-nanopores walls, we develop an equation of state for methane at supercritical temperature over a wide range of pressures. Molecular dynamic simulation data demonstrates that this equation is able to relate very well the methane storage behavior with each of the key physical parameters, including a pore size and shape and wall chemistry and roughness. Moreover, this equation only requires one fitted parameter, and is simple, reliable and powerful in application.

  1. Epitaxial growth of 6H silicon carbide in the temperature range 1320 C to 1390 C

    NASA Technical Reports Server (NTRS)

    Will, H. A.; Powell, J. A.

    1974-01-01

    High-quality epitaxial layers of 6H SiC have been grown on 6H SiC substrates with the grown direction perpendicular to the crystal c-axis. The growth was by chemical vapor deposition from methyltrichlorosilane (CH3SiCl3) in hydrogen at temperatures in the range of 1320 to 1390 C. Epitaxial layers up to 80 microns thick were grown at rates of 0.4 microns/min. Attempts at growth on the (0001) plane of 6H SiC substrates under similar conditions resulted in polycrystalline cubic SiC layers. Optical and X-ray diffraction techniques were used to characterize the grown layers.

  2. Methane storage in nanoporous material at supercritical temperature over a wide range of pressures.

    PubMed

    Wu, Keliu; Chen, Zhangxin; Li, Xiangfang; Dong, Xiaohu

    2016-01-01

    The methane storage behavior in nanoporous material is significantly different from that of a bulk phase, and has a fundamental role in methane extraction from shale and its storage for vehicular applications. Here we show that the behavior and mechanisms of the methane storage are mainly dominated by the ratio of the interaction between methane molecules and nanopores walls to the methane intermolecular interaction, and a geometric constraint. By linking the macroscopic properties of the methane storage to the microscopic properties of a system of methane molecules-nanopores walls, we develop an equation of state for methane at supercritical temperature over a wide range of pressures. Molecular dynamic simulation data demonstrates that this equation is able to relate very well the methane storage behavior with each of the key physical parameters, including a pore size and shape and wall chemistry and roughness. Moreover, this equation only requires one fitted parameter, and is simple, reliable and powerful in application. PMID:27628747

  3. Charge-Induced Long-Range Order in a Room-Temperature Ionic Liquid.

    PubMed

    Ma, Ke; Jarosova, Romana; Swain, Greg M; Blanchard, Gary J

    2016-09-20

    We report direct evidence for charge-induced long-range (ca. 100 μm) order in the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(+)BF4(-)), supported on a silica surface. We have measured the rotational diffusion dynamics of anionic, cationic, and neutral chromophores as a function of distance from a silica surface. The results reflect the excess charge density gradient induced in the IL by the (negative) charge present on the silica surface. Identical measurements in ethylene glycol reveal spatially invariant reorientation dynamics for all chromophores. Capping the silica support with Me2SiCl2 results in spatially invariant reorientation dynamics in the IL. We understand these data in the context of the IL exhibiting a spatially damped piezoelectric response mediated by IL fluidity and disorder. PMID:27563803

  4. Bubble point measurements of the system butane + octylbenzene in the temperature range 290--450 K

    SciTech Connect

    Leeuw, V.V. de; Poot, W.; Loos, T.W. de; Swaan Arons, J. de . Lab. of Applied Thermodynamics and Phase Equilibria)

    1994-01-01

    As a part of research on nitrogen displacement in light-oil reservoirs, the phase behavior of mixtures of a model oil and nitrogen is studied. The model oil consists of methane, butane, and tetradecane or octylbenzene. For reliable phase behavior calculations in the multicomponent system at reservoir conditions -- about 370 K and 50 MPa in the North Sea -- measurements are needed of at least the binary sub-systems in the temperature and pressure range of interest, in order to determine binary interaction coefficients. Bubble points of butane + octylbenzene at eight different mole fractions have been determined at 290--440 K using the synthetic method. The raw experimental data have been fitted using the Peng-Robinson and the Soave-Redlich-Kwong equations of state in combination with a number of different mixing rules.

  5. Oxidation of Fe-C alloys in the temperature range 600-852/sup 0/C

    SciTech Connect

    Malik, A.U.; Whittle, D.P.

    1981-12-01

    The oxidation behavior of Fe-C alloys in the temperature range 600-850/sup 0/C has been studied. CO/sub 2/ evolved during oxidation was measured using an infrared gas analyzer. The presence of C lowers the oxidation rate relative to that of pure Fe and this has been related to the rejection of carbon at the alloy-scale interface causing poor contact between scale and alloy. As a result, the scale contains a higher proportion of magnetite, which reduces its overall growth rate. Very little carbon is lost to the atmosphere. The ease with which the rejected carbon is incorporated into the alloy depends on the alloy structure.

  6. Methane storage in nanoporous material at supercritical temperature over a wide range of pressures

    PubMed Central

    Wu, Keliu; Chen, Zhangxin; Li, Xiangfang; Dong, Xiaohu

    2016-01-01

    The methane storage behavior in nanoporous material is significantly different from that of a bulk phase, and has a fundamental role in methane extraction from shale and its storage for vehicular applications. Here we show that the behavior and mechanisms of the methane storage are mainly dominated by the ratio of the interaction between methane molecules and nanopores walls to the methane intermolecular interaction, and a geometric constraint. By linking the macroscopic properties of the methane storage to the microscopic properties of a system of methane molecules-nanopores walls, we develop an equation of state for methane at supercritical temperature over a wide range of pressures. Molecular dynamic simulation data demonstrates that this equation is able to relate very well the methane storage behavior with each of the key physical parameters, including a pore size and shape and wall chemistry and roughness. Moreover, this equation only requires one fitted parameter, and is simple, reliable and powerful in application. PMID:27628747

  7. Relationship between mean daily ambient temperature range and hospital admissions for schizophrenia: Results from a national cohort of psychiatric inpatients.

    PubMed

    Sung, Tzu-I; Chen, Mu-Jean; Lin, Chuan-Yao; Lung, Shih-Chun; Su, Huey-Jen

    2011-12-01

    Environmental temperature is known to correlate with schizophrenia, but little is known about the association with changes in temperature. This 12-year study aimed to evaluate the relationship between the mean daily range of ambient temperature and schizophrenia admissions in a national cohort of psychiatric inpatients in Taiwan. Meteorological data provided by the Central Weather Bureau of Taiwan were interpolated to create representative estimates. Psychiatric inpatient admissions in all hospitals with medical services enrolled in the current health care insurance system were retrieved from the 1996-2007 Psychiatric Inpatient Medical Claim dataset of the National Health Insurance Research Database. Generalized linear models with Poisson distributions were used to analyze the impact of mean diurnal change of temperature on schizophrenia admissions, controlling for internal correlations and demographic covariates. The daily temperature range varied between 1.7°C and 12.1°C (1st to 99th percentile). The relative risk of schizophrenia admission was significantly increased at a temperature range of 3.2°C (10th percentile), and the maximum was at 12.1°C (99th percentile); however, no such association was found with schizoaffective disorder. When restricted to the capital and largest city, the effects of temperature range were prominent and may correlate with temperature itself. The joint effect of temperature and temperature range was associated with elevated risk, particularly at cooler temperatures. A positive correlation was found between increasing temperature range and schizophrenia admissions. The increase in morbidity at high percentiles suggests that the increasing dynamics of temperature range are a valid reflection of risk, highlighting the need for precautionary action. PMID:22018962

  8. Density and Phonon-Stiffness Anomalies of Water and Ice in the Full Temperature Range.

    PubMed

    Sun, Chang Q; Zhang, Xi; Fu, Xiaojian; Zheng, Weitao; Kuo, Jer-Lai; Zhou, Yichun; Shen, Zexiang; Zhou, Ji

    2013-10-01

    The specific-heat difference between the O:H van der Waals bond and the H-O polar-covalent bond and the Coulomb repulsion between electron pairs on adjacent oxygen atoms determine the angle-length-stiffness relaxation dynamics of the hydrogen bond (O:H-O), which is responsible for the density and phonon-stiffness oscillation of water ice over the full temperature range. Cooling shortens and stiffens the part of relatively lower specific-heat, and meanwhile lengthens and softens the other part of the O:H-O bond via repulsion. Length contraction/elongation of a specific part always stiffens/softens its corresponding phonon. In the liquid and in the solid phase, the O:H bond contracts more than the H-O elongates, hence, an O:H-O cooling contraction and the seemingly "regular" process of cooling densification take place. During freezing, the H-O contracts less than the O:H elongates, leading to an O:H-O elongation and volume expansion. At extremely low temperatures, the O:H-O angle stretching lowers the density slightly as the O:H and the H-O lengths change insignificantly. In ice, the O-O distance is longer than it is in water, resulting in a lower density, so that ice floats. PMID:26706381

  9. Impact of diurnal temperature range on human health: a systematic review

    NASA Astrophysics Data System (ADS)

    Cheng, Jian; Xu, Zhiwei; Zhu, Rui; Wang, Xu; Jin, Liu; Song, Jian; Su, Hong

    2014-02-01

    Increasing epidemiological studies have shown that a rapid temperature change within 1 day is an independent risk factor for human health. This paper aimed to systematically review the epidemiological evidence on the relationship between diurnal temperature range (DTR) and human health and to propose future research directions. A literature search was conducted in October 2013 using the databases including PubMed, ScienceDirect, and EBSCO. Empirical studies regarding the relationship between DTR and mortality and morbidity were included. Twenty-five relevant studies were identified, among which, 11 investigated the relationship between DTR and mortality and 14 examined the impact of DTR on morbidity. The majority of existing studies reported that DTR was significantly associated with mortality and morbidity, particularly for cardiovascular and respiratory diseases. Notably, compared with adults, the elderly and children were more vulnerable to DTR effects. However, there were some inconsistencies regarding the susceptible groups, lag time, and threshold of DTR. The impact of DTR on human health may be confounded or modified by season, socioeconomic, and educational status. Further research is needed to further confirm the adverse effects of DTR in different geographical locations; examine the effects of DTR on the health of children aged one or under; explore extreme DTR effects on human health; analyze the difference of DTR effects on human health in different locations and the modified effects of potential confounding factors; and develop detailed preventive measures against large DTR, particularly for susceptible groups.

  10. Constitutive modeling of polycarbonate over a wide range of strain rates and temperatures

    NASA Astrophysics Data System (ADS)

    Wang, Haitao; Zhou, Huamin; Huang, Zhigao; Zhang, Yun; Zhao, Xiaoxuan

    2016-06-01

    The mechanical behavior of polycarbonate was experimentally investigated over a wide range of strain rates ( 10^{-4} to 5× 103 s^{-1}) and temperatures (293 to 353 K). Compression tests under these conditions were performed using a SHIMADZU universal testing machine and a split Hopkinson pressure bar. Falling weight impact testing was carried out on an Instron Dynatup 9200 drop tower system. The rate- and temperature-dependent deformation behavior of polycarbonate was discussed in detail. Dynamic mechanical analysis (DMA) tests were utilized to observe the glass ( α ) transition and the secondary ( β ) transition of polycarbonate. The DMA results indicate that the α and β transitions have a dramatic influence on the mechanical behavior of polycarbonate. The decompose/shift/reconstruct (DSR) method was utilized to decompose the storage modulus into the α and β components and extrapolate the entire modulus, the α-component modulus and the β-component modulus. Based on three previous models, namely, Mulliken-Boyce, G'Sell-Jonas and DSGZ, an adiabatic model is proposed to predict the mechanical behavior of polycarbonate. The model considers the contributions of both the α and β transitions to the mechanical behavior, and it has been implemented in ABAQUS/Explicit through a user material subroutine VUMAT. The model predictions are proven to essentially coincide with the experimental results during compression testing and falling weight impact testing.

  11. Assessment of Operation of EMK21 MEMS Silicon Oscillator Over Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2009-01-01

    Electronic control systems, data-acquisition instrumentation, and microprocessors require accurate timing signals for proper operation. Traditionally, ceramic resonators and crystal oscillators provided this clock function for the majority of these systems. Over the last few years, MEMS (Micro-Electro-Mechanical Systems) resonator-based oscillators began to surface as commercial-off-the-shelf (COTS) parts by a few companies. These quartz-free, miniature silicon devices could easily replace the traditional crystal oscillators in providing the timing/clock function for many digital and analog circuits. They are reported to provide stable output frequency, offer great tolerance to shock and vibration, and are immune to electro-static discharge [ 1-2]. In addition, they are encapsulated in compact lead-free packages and cover a wide frequency range (1 MHz to 125 MHz). The small size of the MEMS oscillators along with their thermal stability make them ideal candidates for use in space exploration missions. Limited data, however, exist on the performance and reliability of these devices under operation in applications where extreme temperatures or thermal cycling swings, which are typical of space missions, are encountered. This report presents the results of the work obtained on the evaluation of an Ecliptek Corporation MEMS silicon oscillator chip under extreme temperatures.

  12. Impact of diurnal temperature range on human health: a systematic review.

    PubMed

    Cheng, Jian; Xu, Zhiwei; Zhu, Rui; Wang, Xu; Jin, Liu; Song, Jian; Su, Hong

    2014-11-01

    Increasing epidemiological studies have shown that a rapid temperature change within 1 day is an independent risk factor for human health. This paper aimed to systematically review the epidemiological evidence on the relationship between diurnal temperature range (DTR) and human health and to propose future research directions. A literature search was conducted in October 2013 using the databases including PubMed, ScienceDirect, and EBSCO. Empirical studies regarding the relationship between DTR and mortality and morbidity were included. Twenty-five relevant studies were identified, among which, 11 investigated the relationship between DTR and mortality and 14 examined the impact of DTR on morbidity. The majority of existing studies reported that DTR was significantly associated with mortality and morbidity, particularly for cardiovascular and respiratory diseases. Notably, compared with adults, the elderly and children were more vulnerable to DTR effects. However, there were some inconsistencies regarding the susceptible groups, lag time, and threshold of DTR. The impact of DTR on human health may be confounded or modified by season, socioeconomic, and educational status. Further research is needed to further confirm the adverse effects of DTR in different geographical locations; examine the effects of DTR on the health of children aged one or under; explore extreme DTR effects on human health; analyze the difference of DTR effects on human health in different locations and the modified effects of potential confounding factors; and develop detailed preventive measures against large DTR, particularly for susceptible groups. PMID:24535132

  13. Thermodynamic and Transport Properties of Real Air Plasma in Wide Range of Temperature and Pressure

    NASA Astrophysics Data System (ADS)

    Wang, Chunlin; Wu, Yi; Chen, Zhexin; Yang, Fei; Feng, Ying; Rong, Mingzhe; Zhang, Hantian

    2016-07-01

    Air plasma has been widely applied in industrial manufacture. In this paper, both dry and humid air plasmas' thermodynamic and transport properties are calculated in temperature 300-100000 K and pressure 0.1-100 atm. To build a more precise model of real air plasma, over 70 species are considered for composition. Two different methods, the Gibbs free energy minimization method and the mass action law method, are used to determinate the composition of the air plasma in a different temperature range. For the transport coefficients, the simplified Chapman-Enskog method developed by Devoto has been applied using the most recent collision integrals. It is found that the presence of CO2 has almost no effect on the properties of air plasma. The influence of H2O can be ignored except in low pressure air plasma, in which the saturated vapor pressure is relatively high. The results will serve as credible inputs for computational simulation of air plasma. supported by the National Key Basic Research Program of China (973 Program)(No. 2015CB251002), National Natural Science Foundation of China (Nos. 51521065, 51577145), the Science and Technology Project Funds of the Grid State Corporation (SGTYHT/13-JS-177), the Fundamental Research Funds for the Central Universities, and State Grid Corporation Project (GY71-14-004)

  14. Density and Phonon-Stiffness Anomalies of Water and Ice in the Full Temperature Range.

    PubMed

    Sun, Chang Q; Zhang, Xi; Fu, Xiaojian; Zheng, Weitao; Kuo, Jer-Lai; Zhou, Yichun; Shen, Zexiang; Zhou, Ji

    2013-10-01

    The specific-heat difference between the O:H van der Waals bond and the H-O polar-covalent bond and the Coulomb repulsion between electron pairs on adjacent oxygen atoms determine the angle-length-stiffness relaxation dynamics of the hydrogen bond (O:H-O), which is responsible for the density and phonon-stiffness oscillation of water ice over the full temperature range. Cooling shortens and stiffens the part of relatively lower specific-heat, and meanwhile lengthens and softens the other part of the O:H-O bond via repulsion. Length contraction/elongation of a specific part always stiffens/softens its corresponding phonon. In the liquid and in the solid phase, the O:H bond contracts more than the H-O elongates, hence, an O:H-O cooling contraction and the seemingly "regular" process of cooling densification take place. During freezing, the H-O contracts less than the O:H elongates, leading to an O:H-O elongation and volume expansion. At extremely low temperatures, the O:H-O angle stretching lowers the density slightly as the O:H and the H-O lengths change insignificantly. In ice, the O-O distance is longer than it is in water, resulting in a lower density, so that ice floats.

  15. Diurnal temperature range and short-term mortality in large US communities

    NASA Astrophysics Data System (ADS)

    Lim, Youn-Hee; Reid, Colleen E.; Mann, Jennifer K.; Jerrett, Michael; Kim, Ho

    2015-09-01

    Research has shown that diurnal temperature range (DTR) is significantly associated with mortality and morbidity in regions of Asia; however, few studies have been conducted in other regions such as North America. Thus, we examined DTR effects on mortality in the USA. We used mortality and environmental data from the National Morbidity Mortality Air Pollution Study (NMMAPS). The data are daily mortality, air pollution, and temperature statistics from 95 large US communities collected between 1987 and 2000. To assess community-specific DTR effects on mortality, we used Poisson generalized linear models allowing for over-dispersion. After assessing community-specific DTR effects on mortality, we estimated region- and age-specific effects of DTR using two-level normal independent sampling estimation. We found a significant increase of 0.27 % [95 % confidence intervals (CI), 0.24-0.30 %] in nonaccidental mortality across 95 communities in the USA associated with a 1 °C increase in DTR, controlling for apparent temperature, day of the week, and time trend. This overall effect was driven mainly by effects of DTR on cardiovascular and respiratory mortality in the elderly: Mortality in the above 65 age group increased by 0.39 % (95 % CI, 0.33-0.44 %) and 0.33 % (95 % CI, 0.22-0.44 %), respectively. We found some evidence of regional differences in the effects of DTR on nonaccidental mortality with the highest effects in Southern California [0.31 % (95 % CI, 0.21-0.42 %)] and smallest effects in the Northwest and Upper Midwest regions [0.22 % (95 % CI, 0.11-0.33 %) and 0.22 % (95 % CI, 0.07-0.37 %), respectively]. These results indicate a statistically significant association between DTR and mortality on average for 95 large US communities. The findings indicate that DTR impacts on nonaccidental and cardiovascular-related mortality in most US regions and the elderly population was most vulnerable to the effects of DTR.

  16. Wide Operating Temperature Range Electrolytes for High Voltage and High Specific Energy Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Hwang, C.; Krause, F. C.; Soler, J.; West, W. C.; Ratnakumar, B. V.; Amine, K.

    2012-01-01

    A number of electrolyte formulations that have been designed to operate over a wide temperature range have been investigated in conjunction with layered-layered metal oxide cathode materials developed at Argonne. In this study, we have evaluated a number of electrolytes in Li-ion cells consisting of Conoco Phillips A12 graphite anodes and Toda HE5050 Li(1.2)Ni(0.15)Co(0.10)Mn(0.55)O2 cathodes. The electrolytes studied consisted of LiPF6 in carbonate-based electrolytes that contain ester co-solvents with various solid electrolyte interphase (SEI) promoting additives, many of which have been demonstrated to perform well in 4V systems. More specifically, we have investigated the performance of a number of methyl butyrate (MB) containing electrolytes (i.e., LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + MB (20:20:60 v/v %) that contain various additives, including vinylene carbonate, lithium oxalate, and lithium bis(oxalato)borate (LiBOB). When these systems were evaluated at various rates at low temperatures, the methyl butyrate-based electrolytes resulted in improved rate capability compared to cells with all carbonate-based formulations. It was also ascertained that the slow cathode kinetics govern the generally poor rate capability at low temperature in contrast to traditionally used LiNi(0.80)Co(0.15)Al(0.05)O2-based systems, rather than being influenced strongly by the electrolyte type.

  17. High-speed Imaging of Global Surface Temperature Distributions on Hypersonic Ballistic-Range Projectiles

    NASA Technical Reports Server (NTRS)

    Wilder, Michael C.; Reda, Daniel C.

    2004-01-01

    The NASA-Ames ballistic range provides a unique capability for aerothermodynamic testing of configurations in hypersonic, real-gas, free-flight environments. The facility can closely simulate conditions at any point along practically any trajectory of interest experienced by a spacecraft entering an atmosphere. Sub-scale models of blunt atmospheric entry vehicles are accelerated by a two-stage light-gas gun to speeds as high as 20 times the speed of sound to fly ballistic trajectories through an 24 m long vacuum-rated test section. The test-section pressure (effective altitude), the launch velocity of the model (flight Mach number), and the test-section working gas (planetary atmosphere) are independently variable. The model travels at hypersonic speeds through a quiescent test gas, creating a strong bow-shock wave and real-gas effects that closely match conditions achieved during actual atmospheric entry. The challenge with ballistic range experiments is to obtain quantitative surface measurements from a model traveling at hypersonic speeds. The models are relatively small (less than 3.8 cm in diameter), which limits the spatial resolution possible with surface mounted sensors. Furthermore, since the model is in flight, surface-mounted sensors require some form of on-board telemetry, which must survive the massive acceleration loads experienced during launch (up to 500,000 gravities). Finally, the model and any on-board instrumentation will be destroyed at the terminal wall of the range. For these reasons, optical measurement techniques are the most practical means of acquiring data. High-speed thermal imaging has been employed in the Ames ballistic range to measure global surface temperature distributions and to visualize the onset of transition to turbulent-flow on the forward regions of hypersonic blunt bodies. Both visible wavelength and infrared high-speed cameras are in use. The visible wavelength cameras are intensified CCD imagers capable of integration

  18. Medium-Range Predictability of Contrail-Cirrus Demonstrated during Experiments Ml-Cirrus and Access-Ii

    NASA Astrophysics Data System (ADS)

    Schumann, U.

    2015-12-01

    The Contrail Cirrus Prediction model CoCiP (doi:10.5194/gmd-5-543-2012) has been applied quasi operationally to predict contrails for flight planning of ML-CIRRUS (C. Voigt, DLR, et al.) in Europe and for ACCESS II in California (B. Anderson, NASA, et al.) in March-May 2014. The model uses NWP data from ECMWF and past airtraffic data (actual traffic data are used for analysis). The forecasts provided a sequence of hourly forecast maps of contrail cirrus optical depth for 3.5 days, every 12 h. CoCiP has been compared to observations before, e.g. within a global climate-aerosol-contrail model (Schumann, Penner et al., ACPD, 2015, doi:10.5194/acpd-15-19553-2015). Good predictions would allow for climate optimal routing (see, e.g., US patent by Mannstein and Schumann, US 2012/0173147 A1). The predictions are tested by: 1) Local eyewitness reports and photos, 2) satellite observed cloudiness, 3) autocorrelation analysis of predictions for various forecast periods, 4) comparisons of computed with observed optical depth from COCS (doi:10.5194/amt-7-3233-2014, 2014) by IR METEOSAT-SEVIRI observations over Europe. The results demonstrate medium-range predictability of contrail cirrus to a useful degree for given traffic, soot emissions, and high-quality NWP data. A growing set of satellite, Lidar, and in-situ data from ML-CIRRUS and ACCENT are becoming available and will be used to further test the forecast quality. The autocorrelation of optical depth predictions is near 70% for 3-d forecasts for Europe (outside times with high Sahara dust loads), and only slightly smaller for continental USA. Contrail cirrus is abundant over Europe and USA. More than 1/3 of all cirrus measured with the research aircraft HALO during ML-CIRRUS was impacted by contrails. The radiative forcing (RF) is strongly daytime and ambience dependent. The net annual mean RF, based on our global studies, may reach up to 0.08 W/m2 globally, and may well exceed 1 W/m2 regionally, with maximum over Europe

  19. Homeostasis of the temperature sensitivity of respiration over a range of growth temperatures indicated by a modified Arrhenius model.

    PubMed

    Noguchi, Ko; Yamori, Wataru; Hikosaka, Kouki; Terashima, Ichiro

    2015-07-01

    The temperature dependence of plant respiratory rate (R) changes in response to growth temperature. Here, we used a modified Arrhenius model incorporating the temperature dependence of activation energy (Eo ), and compared the temperature dependence of R between cold-sensitive and cold-tolerant species. We analyzed the temperature dependences of leaf CO2 efflux rate of plants cultivated at low (LT) or high temperature (HT). In plants grown at HT (HT plants), Eo at low measurement temperature varied among species, but Eo at growth temperature in HT plants did not vary and was comparable to that in plants grown at LT (LT plants), suggesting that the limiting process was similar at the respective growth temperatures. In LT plants, the integrated value of loge R, a measure of respiratory capacity, in cold-sensitive species was lower than that in cold-tolerant species. When plants were transferred from HT to LT, the respiratory capacity changed promptly after the transfer compared with the other parameters. These results suggest that a similar process limits R at different growth temperatures, and that the lower capacity of the respiratory system in cold-sensitive species may explain their low growth rate at LT.

  20. The Effect of a Pre-Lens Aperture on the Temperature Range and Image Uniformity of Microbolometer Infrared Cameras

    SciTech Connect

    Dinwiddie, Ralph Barton; Parris, Larkin S.; Lindal, John M.; Kunc, Vlastimil

    2016-01-01

    This paper explores the temperature range extension of long-wavelength infrared (LWIR) cameras by placing an aperture in front of the lens. An aperture smaller than the lens will reduce the radiance to the sensor, allowing the camera to image targets much hotter than typically allowable. These higher temperatures were accurately determined after developing a correction factor which was applied to the built-in temperature calibration. The relationship between aperture diameter and temperature range is linear. The effect of pre-lens apertures on the image uniformity is a form of anti-vignetting, meaning the corners appear brighter (hotter) than the rest of the image. An example of using this technique to measure temperatures of high melting point polymers during 3D printing provide valuable information of the time required for the weld-line temperature to fall below the glass transition temperature.

  1. Statistical Significance of Long-Range `Optimal Climate Normal' Temperature and Precipitation Forecasts.

    NASA Astrophysics Data System (ADS)

    Wilks, Daniel S.

    1996-04-01

    A simple approach to long-range forecasting of monthly or seasonal quantities is as the average of observations over some number of the most recent years. Finding this `optimal climate normal' (OCN) involves examining the relationships between the observed variable and averages of its values over the previous one to 30 years and selecting the averaging period yielding the best results. This procedure involves a multiplicity of comparisons, which will lead to misleadingly positive results for developments data. The statistical significance of these OCNs are assessed here using a resampling procedure, in which time series of U.S. Climate Division data are repeatedly shuffled to produce statistical distributions of forecast performance measures, under the null hypothesis that the OCNs exhibit no predictive skill. Substantial areas in the United States are found for which forecast performance appears to be significantly better than would occur by chance.Another complication in the assessment of the statistical significance of the OCNs derives from the spatial correlation exhibited by the data. Because of this correlation, instances of Type I errors (false rejections of local null hypotheses) will tend to occur with spatial coherency and accordingly have the potential to be confused with regions for which there may be real predictability. The `field significance' of the collections of local tests is also assessed here by simultaneously and coherently shuffling the time series for the Climate Divisions. Areas exhibiting significant local tests are large enough to conclude that seasonal OCN temperature forecasts exhibit significant skill over parts of the United States for all seasons except SON, OND, and NDJ, and that seasonal OCN precipitation forecasts are significantly skillful only in the fall. Statistical significance is weaker for monthly than for seasonal OCN temperature forecasts, and the monthly OCN precipitation forecasts do not exhibit significant predictive

  2. Acute effects of diurnal temperature range on mortality in 8 Chinese cities.

    PubMed

    Zhou, Xiaodan; Zhao, Ang; Meng, Xia; Chen, Renjie; Kuang, Xingya; Duan, Xiaoli; Kan, Haidong

    2014-09-15

    Diurnal temperature range (DTR) is a meteorological indicator closely associated with global climate change. There have been no multicity studies in China addressing the DTR-related health impact. We hypothesized that an increase of DTR is associated with higher daily mortality with a potential lag of effect, and investigated the acute effects of DTR on total, cardiovascular, and respiratory mortality in 8 large Chinese cities from 2001 to 2010. We first calculated city-specific effect of DTR in the full year, the cool season (November to the next April) and the warm season (May to October) separately using a semi-parametric generalized additive model; then we pooled the city-specific estimates with meta analysis. After adjusting for long-term and seasonal trends, temperature, relative humidity and air pollution levels, we found statistically significant associations between DTR and daily mortality, especially in cool seasons. A 1 °C increment of DTR on lag-day 1 corresponded to a 0.42% (95% CI, 0.14 to 0.70) increase in total non-accidental mortality, 0.45% (95% CI, 0.26 to 0.65) increase in cardiovascular mortality, and a 0.76% (95% CI, 0.24 to 1.29) increase in respiratory mortality in cool seasons. Deaths among females and elderly (≥ 65 years) were more strongly associated with DTR than among males and younger people (<65 years). Our analysis suggests that DTR is a potential trigger for death in China. Our findings may have important implications for the climate policies in the country. PMID:24937494

  3. Assessing the Influence of Precipitation on Diurnal Temperature Range Changes: Implications for Climate Change Projection

    NASA Astrophysics Data System (ADS)

    Van den Hoof, C.; Garreaud, R.

    2014-12-01

    . Braganza, D.J. Karoly, and J.M. Arblaster. Diurnal temperature range as an index of global climate change during the twentieth century. Geophysical Research Letters, 31:1-4, 2004. [2] A. Dai, A.D. Del Genio, and I.Y. Fung. Clouds, precipitation and temperature range. Nature, 386:665-666, 1997.

  4. Comprehensive approach to understand the association between diurnal temperature range and mortality in East Asia.

    PubMed

    Kim, Jayeun; Shin, Jihye; Lim, Youn-Hee; Honda, Yasushi; Hashizume, Masahiro; Guo, Yue Leon; Kan, Haidong; Yi, Seungmuk; Kim, Ho

    2016-01-01

    An adverse association between diurnal temperature range (DTR) and mortality has been suggested, but with variable relationships in different cities. Comprehensive approaches to understanding the health effects of DTR using multinational data are required. We investigated the association between DTR and cause-specific mortality in an age-specific population and assessed the dependency of the health effects of DTR on geographic and climatic factors. Poisson generalized linear regression analyses with allowances for over-dispersion were applied to daily DTR and cause-specific mortality data from 30 cities in China, Japan, Korea, and Taiwan between 1979 and 2010, adjusted for various climatic and environmental factors. City-specific effects of DTR were estimated and summarized for the overall effects using geographic and climatic determinants in a meta-analysis. For all-cause, circulatory, and respiratory mortality, the greatest city-specific effects per 1°C DTR were found in Tianjin, China (1.80%; 95% confidence interval [CI]: 0.48, 3.14); Tangshan, China (2.25%; 95% CI: 0.65, 3.87); and Incheon, Korea (2.84%; 95% CI: 0.04, 5.73), respectively, and overall effects across 30 cities were 0.58% (95% CI: 0.44, 0.72), 0.81% (95% CI: 0.60, 1.03), and 0.90% (95% CI: 0.63, 1.18), respectively. Using quartile cutoff values for climatic (DTR, and mean temperature) and geographic (latitude, and longitude) characteristics, we divided the 30 cities into 4 different groups and conducted a meta-analysis within the groups using either a random or fixed effects model. Adverse effects of DTR were more pronounced for those aged ≥65years and varied according to geographic, longitudinal (0.07%; 95% CI: 0.05, 0.10), and climatic characteristics and the scale of DTR (0.33%; 95% CI: 0.12, 0.55) for overall all-cause mortality. The DTR is a risk factor affecting human health, depending on geographic location and the temperature variation, with particular vulnerability in aged populations

  5. Low-temperature interface between the gas and solid phases of hard spheres with a short-ranged attraction.

    PubMed

    Sear, R P

    1999-06-01

    At low temperature, spheres with a very short-ranged attraction exist as a near-close-packed solid coexisting with an almost infinitely dilute gas. We find that the ratio of the interfacial tension between these two phases to the thermal energy diverges as the range of the attraction tends to zero. The large tensions when the interparticle attractions are short ranged may be why globular proteins only crystallize over a narrow range of conditions. PMID:11969672

  6. Declining pine growth in Central Spain coincides with increasing diurnal temperature range since the 1970s

    NASA Astrophysics Data System (ADS)

    Büntgen, Ulf; Martínez-Peña, Fernando; Aldea, Jorge; Rigling, Andreas; Fischer, Erich M.; Camarero, J. Julio; Hayes, Michael J.; Fatton, Vincent; Egli, Simon

    2013-08-01

    Growing evidence suggests environmental change to be most severe across the semi-arid subtropics, with past, present and projected drying of the Mediterranean Basin posing a key multidisciplinary challenge. Consideration of a single climatic factor, however, often fails to explain spatiotemporal growth dynamics of drought-prone ecosystems. Here, we present annually resolved and absolutely dated ring width measurements of 871 Scots pines (Pinus sylvestris) from 18 individual plot sites in the Central Spanish Pinar Grande forest reserve. Although comprising tree ages from 6 to 175 years, this network correlates surprisingly well with the inverse May-July diurnal temperature range (r = 0.84; p < 0.00011956-2011). Ring width extremes were triggered by pressure anomalies of the North Atlantic Oscillation, and the long-term growth decline coincided with Iberian-wide drying since the mid-1970s. Climate model simulations not only confirm this negative trend over the last decades but also project drought to continuously increase over the 21st century. Associated ecological effects and socio-economic consequences should be considered to improve adaptation strategies of agricultural and forest management, as well as biodiversity conservation and ecosystem service.

  7. Diurnal temperature range trend over North Carolina and the associated mechanisms

    NASA Astrophysics Data System (ADS)

    Sayemuzzaman, Mohammad; Mekonnen, Ademe; Jha, Manoj K.

    2015-06-01

    This study seeks to investigate the variability and presence of trend in the diurnal surface air temperature range (DTR) over North Carolina (NC) for the period 1950-2009. The significance trend test and the magnitude of trends were determined using the non-parametric Mann-Kendall test and the Theil-Sen approach, respectively. Statewide significant trends (p < 0.05) of decreasing DTR were found in all seasons and annually during the analysis period. Highest (lowest) temporal DTR trends of magnitude - 0.19 (- 0.031) °C/decade were found in summer (winter). Potential mechanisms for the presence/absence of trend in DTR have been highlighted. Historical data sets of the three main moisture components (precipitation, total cloud cover (TCC), and soil moisture) and the two major atmospheric circulation modes (North Atlantic Oscillation and Southern Oscillation) were used for correlation analysis. The DTRs were found to be negatively correlated with the precipitation, TCC and soil moisture across the state for all the seasons and annual basis. It appears that the moisture components related better to the DTR than to the atmospheric circulation modes.

  8. Effect of holding time in the ({alpha} + {gamma}) temperature range on toughness of specially austempered ductile iron

    SciTech Connect

    Kobayashi, T.; Yamada, S.

    1996-07-01

    Austempered ductile iron (ADI) finds wide application in the industry because of its high strength and toughness. The QB{prime} process has been developed to produce a fine microstructure with high fracture toughness in ADI. This process involves reaustenitizing a prequenched ductile iron in the ({alpha} + {gamma}) temperature range followed by an isothermal treatment in the bainitic transformation temperature range. In the present work, the effect of holding time in the ({alpha} + {gamma}) temperature range on the structure and un-notched toughness of ADI has been studied. Prior to the austempering treatment, the as-cast ductile iron was heat treated to obtain martensitic, ferritic, and pearlitic matrix structures. In the case of prequenched material (martensitic matrix), the un-notched impact toughness increased as a function of holding time in the ({alpha} + {gamma}) temperature range. The reaustenitization heat treatment also resulted in the precipitation of fine carbide particles, identified as (Fe,Cr,Mn){sub 3}C. It was shown that the increase in holding time in the ({alpha} + {gamma}) temperature range leads to a reduction in the number of carbide particles. In the case of a ferritic prior structure, a long duration hold in the ({alpha} + {gamma}) temperature range resulted in the coarsening of the structure with a marginal increase in the toughness. In the case of a pearlitic prior structure, the toughness increased with holding time. This was attributed to the decomposition of the relatively stable carbide around the eutectic cell boundary with longer holding times.

  9. Effect of Holding Time in the (α + γ) Temperature Range on Toughness of Specially Austempered Ductile Iron

    NASA Astrophysics Data System (ADS)

    Kobayashi, Toshiro; Yamada, Shinya

    1996-07-01

    Austempered ductile iron (ADI) finds wide application in the industry because of its high strength and toughness. The QB' process has been developed to produce a fine microstructure with high fracture toughness in ADI. This process involves reaustenitizing a prequenched ductile iron in the (α + γ) temperature range followed by an isothermal treatment in the bainitic transformation tem-perature range. In the present work, the effect of holding time in the (α + γ) temperature range on the structure and un-notched toughness of ADI has been studied. Prior to the austempering treatment, the as-cast ductile iron was heat treated to obtain martensitic, ferritic, and pearlitic matrix structures. In the case of prequenched material (martensitic matrix), the un-notched impact toughness increased as a function of holding time in the (α + γ) temperature range. The reaustenitization heat treatment also resulted in the precipitation of fine carbide particles, identified as (Fe,Cr,Mn)3C. It was shown that the increase in holding time in the (α + γ) temperature range leads to a reduction in the number of carbide particles. In the case of a ferritic prior structure, a long duration hold in the (α + γ) temperature range resulted in the coarsening of the structure with a marginal increase in the tough-ness. In the case of a pearlitic prior structure, the toughness increased with holding time. This was attributed to the decomposition of the relatively stable carbide around the eutectic cell boundary with longer holding times.

  10. Lead retention by broiler litter biochars in small arms range soil: impact of pyrolysis temperature.

    PubMed

    Uchimiya, Minori; Bannon, Desmond I; Wartelle, Lynda H; Lima, Isabel M; Klasson, K Thomas

    2012-05-23

    Phosphorus-rich manure biochar has a potential for stabilizing Pb and other heavy metal contaminants, as well as serving as a sterile fertilizer. In this study, broiler litter biochars produced at 350 and 650 °C were employed to understand how biochar's elemental composition (P, K, Ca, Mg, Na, Cu, Pb, Sb, and Zn) affects the extent of heavy metal stabilization. Soil incubation experiments were conducted using a sandy, slightly acidic (pH 6.11) Pb-contaminated (19906 mg kg(-1) total Pb primarily as PbCO(3)) small arms range (SAR) soil fraction (<250 μm) amended with 2-20 wt % biochar. The Pb stabilization in pH 4.9 acetate buffer reached maximum at lower (2-10 wt %) biochar amendment rate, and 350 °C biochar containing more soluble P was better able to stabilize Pb than the 650 °C biochar. The 350 °C biochar consistently released greater amounts of P, K, Mg, Na, and Ca than 650 °C biochar in both unbuffered (pH 4.5 sulfuric acid) and buffered (pH 4.9 acetate) systems, despite 1.9-4.5-fold greater total content of the 650 °C biochar. Biochars, however, did not influence the total extractable Pb over three consecutive equilibration periods consisting of (1) 1 week in pH 4.5 sulfuric acid (simulated leaching by rainfall), (2) 1 week in pH 4.9 acetate buffer (standard solution for toxicity characteristic leaching procedure), and (3) 1 h in pH 1.5 glycine at 37 °C (in vitro bioaccessibility procedure). Overall, lower pyrolysis temperature was favorable for stabilizing Pb (major risk driver of SAR soils) and releasing P, K, Ca, and other plant nutrients in a sandy acidic soil. PMID:22548418

  11. Kinetics of the reaction of Cl atoms with CHCl 3 over the temperature range 253-313 K

    NASA Astrophysics Data System (ADS)

    Nilsson, Elna J. K.; Hoff, Janus; Nielsen, Ole John; Johnson, Matthew S.

    2010-07-01

    The reaction CHCl 3 + Cl → CCl 3 + HCl was studied in the atmospherically relevant temperature range from 253 to 313 K and in 930 mbar of N 2 diluent using the relative rate method. A temperature dependent reaction rate constant, valid in the temperature range 220-330 K, was determined by a fit to the result of the present study and that of Orlando (1999); k = (3.77 ± 0.32) × 10 -12 exp((-1011 ± 24)/T) cm 3 molecule -1 s -1.

  12. Carbon films embedded by nickel nanoparticles: fluctuation in hopping rate and variable-range hopping with respect to annealing temperature

    NASA Astrophysics Data System (ADS)

    Dalouji, Vali; Elahi, Smohammad; Solaymani, Shahram; Ghaderi, Atefeh; Elahi, Hossein

    2016-05-01

    In this work, the electrical properties of carbon-nickel films annealed at different temperatures (573, 773, 1073 and 1273 K) in the temperature range 15-300 K were investigated. The films were grown by radio frequency magnetron co-sputtering on quartz substrates at room temperature. The multiphonon hopping conduction mechanism is found to dominate the electrical transport in the temperature range 150-300 K. It can be seen that the room-temperature hopping rate (ΓRT) at 773 K has maximum value of 56.8 × 105 s-1. Our results of conductivity measurements at high temperature are in good agreement with strong carrier-lattice coupling model; on the other hand, the conductivity in the range 15-50 K is well described in terms of variable-range hopping (VRH) conduction mechanism. The localized state density around Fermi level N( E F) and the average hopping energy W hop at low temperature for the films annealed at 773 K have maximum value of 2.23 × 1023 (cm-3 eV-1) and minimum value of 9.74 × 10-4 eV, respectively.

  13. Kinetic Testing of Nitrate-Based Sodalite Formation Over the Temperature Range of 40 to 100 Degrees Centigrade (Final Report)

    SciTech Connect

    Mattus, A.J.

    2001-09-07

    The focus of this study was the desilication kinetics of a Savannah River Site (SRS) tank farm 2H simulant over the temperature range of 40 to 100 C. Results showed that the formation of nitrate-nitrite-based sodalite over aluminum-to-silicon (Al:Si) molar ratios ranging from 1:1 to 20:1 exhibited overall-second order kinetics. The Arrhenius apparent activation energy associated with the crystal growth process of the sodalite was determined to be 35 kJ/mol over the temperature range investigated. Second-order rate constants were extrapolated to the 2H evaporator working temperature of {approx} 130 C and were found to be 0.012 L mol{sup -1} s{sup -1}. At this operating temperature, the half-life of a limiting reactant with a 0.1 M feed would be 14 min.

  14. Intraspecific variation in thermal acclimation of photosynthesis across a range of temperatures in a perennial crop.

    PubMed

    Zaka, Serge; Frak, Ela; Julier, Bernadette; Gastal, François; Louarn, Gaëtan

    2016-01-01

    Interest in the thermal acclimation of photosynthesis has been stimulated by the increasing relevance of climate change. However, little is known about intra-specific variations in thermal acclimation and its potential for breeding. In this article, we examined the difference in thermal acclimation between alfalfa (Medicago sativa) cultivars originating from contrasting origins, and sought to analyze the mechanisms in play. A series of experiments was carried out at seven growth temperatures between 5 and 35 °C using four cultivars from temperate and Mediterranean origin. Leaf traits, the photosynthetic rate at 25 °C (A400 (25)), the photosynthetic rate at optimal temperature (A400 (opt)), the thermal optimum of photosynthesis (Topt), and the photosynthetic parameters from the Farqhuar model were determined. Irrespective of cultivar origin, a clear shift in the temperature responses of photosynthesis was observed as a function of growth temperature, affecting thermal optimum of photosynthesis, photosynthetic rate at optimal temperature and photosynthetic rate at 25 °C. For both cultivars, Topt values increased linearly in leaves grown between 5 and 35 °C. Relative homeostasis of A400 (25) and A400 (opt) was found between 10 °C and 30 °C growth temperatures, but sharp declines were recorded at 5 and 35 °C. This homeostasis was achieved in part through modifications to leaf nitrogen content, which increased at extreme temperatures. Significant changes were also recorded regarding nitrogen partitioning in the photosynthetic apparatus and in the temperature dependence of photosynthetic parameters. The cultivars differed only in terms of the temperature response of photosynthetic parameters, with Mediterranean genotypes displaying a greater sensitivity of the maximum rate of Rubisco carboxylation to elevated temperatures. It was concluded that intra-specific variations in the temperature acclimation of photosynthesis exist among alfalfa cultivars

  15. Intraspecific variation in thermal acclimation of photosynthesis across a range of temperatures in a perennial crop

    PubMed Central

    Zaka, Serge; Frak, Ela; Julier, Bernadette; Gastal, François; Louarn, Gaëtan

    2016-01-01

    Interest in the thermal acclimation of photosynthesis has been stimulated by the increasing relevance of climate change. However, little is known about intra-specific variations in thermal acclimation and its potential for breeding. In this article, we examined the difference in thermal acclimation between alfalfa (Medicago sativa) cultivars originating from contrasting origins, and sought to analyze the mechanisms in play. A series of experiments was carried out at seven growth temperatures between 5 and 35 °C using four cultivars from temperate and Mediterranean origin. Leaf traits, the photosynthetic rate at 25 °C (A40025), the photosynthetic rate at optimal temperature (A400opt), the thermal optimum of photosynthesis (Topt), and the photosynthetic parameters from the Farqhuar model were determined. Irrespective of cultivar origin, a clear shift in the temperature responses of photosynthesis was observed as a function of growth temperature, affecting thermal optimum of photosynthesis, photosynthetic rate at optimal temperature and photosynthetic rate at 25 °C. For both cultivars, Topt values increased linearly in leaves grown between 5 and 35 °C. Relative homeostasis of A40025 and A400opt was found between 10 °C and 30 °C growth temperatures, but sharp declines were recorded at 5 and 35 °C. This homeostasis was achieved in part through modifications to leaf nitrogen content, which increased at extreme temperatures. Significant changes were also recorded regarding nitrogen partitioning in the photosynthetic apparatus and in the temperature dependence of photosynthetic parameters. The cultivars differed only in terms of the temperature response of photosynthetic parameters, with Mediterranean genotypes displaying a greater sensitivity of the maximum rate of Rubisco carboxylation to elevated temperatures. It was concluded that intra-specific variations in the temperature acclimation of photosynthesis exist among alfalfa cultivars, but that

  16. Electronic weighing, identification and subdermal body temperature sensing of range livestock

    SciTech Connect

    Anderson, D.M.; Landt, J.A.; Salazar, P.H.

    1980-01-01

    Individual animal weights can be obtained manually or automatically in a computer-compatible format with an electronic scale. If an electronic identification, subdermal body temperature sensing unit is interfaced with an electronic scale, the weight, identification, and subdermal body temperature of individually identified animals can be obtained either manually or automatically, and transcriptional and phonetic errors thus eliminated. Electronics can be used at remote locations despite extreme temperatures, dust, and fluctuation in battery power. For research purposes, daily weight fluctuations, watering behavior, and subdermal body temperature can be recorded continuously. When the system becomes commercially available, increased livestock production at a lower cost will be possible.

  17. Sensitivity-Improved Strain Sensor over a Large Range of Temperatures Using an Etched and Regenerated Fiber Bragg Grating

    PubMed Central

    Wang, Yupeng; Qiao, Xueguang; Yang, Hangzhou; Su, Dan; Li, Ling; Guo, Tuan

    2014-01-01

    A sensitivity-improved fiber-optic strain sensor using an etched and regenerated fiber Bragg grating (ER-FBG) suitable for a large range of temperature measurements has been proposed and experimentally demonstrated. The process of chemical etching (from 125 μm to 60 μm) provides regenerated gratings (at a temperature of 680 °C) with a stronger reflective intensity (from 43.7% to 69.8%), together with an improved and linear strain sensitivity (from 0.9 pm/με to 4.5 pm/με) over a large temperature range (from room temperature to 800 °C), making it a useful strain sensor for high temperature environments. PMID:25299954

  18. A Modified Johnson-Cook Model for Advanced High-Strength Steels Over a Wide Range of Temperatures

    NASA Astrophysics Data System (ADS)

    Qingdong, Zhang; Qiang, Cao; Xiaofeng, Zhang

    2014-12-01

    Advanced high-strength steel (AHSS) is widely used in automotive industry. In order to investigate the mechanical behaviors of AHSS over a wide range of temperatures, quasi-static tensile experiments were conducted at the temperatures from 298 to 1073 K on a Gleeble-3500 thermo-simulation machine. The results show that flow behaviors are affected by testing temperature significantly. In order to describe the flow features of AHSS, the Johnson-Cook (JC) model is employed. By introducing polynomial functions to consider the effects of temperature on hardening behavior, the JC model is modified and used to predict flow behavior of AHSS at different experimental conditions. The accuracy of the modified JC model is verified and the predicted flow stress is in good agreement with experimental results, which confirms that the modified JC model can give an accurate and precise estimate over a wide range of temperatures.

  19. Innovative use of Distributed Temperature Sensing and Meteorological Data to Understand Thermoregulation of Free-Ranging Howling Monkeys

    NASA Astrophysics Data System (ADS)

    Suarez, F. I.; Vinyard, C. J.; Williams, S. H.; Hausner, M. B.; Tyler, S. W.; Glander, K.

    2011-12-01

    Temperature fluctuations are a major driver of change in natural habitats and influence the lifestyle of all organisms because temperature impacts molecular, physiological, and behavioral processes. However, there is a lack of understanding on how temperature affects metabolism, behavior, and ecology at the organismal level. Even though physiological responses to temperature fluctuations have been well documented in laboratory conditions, it has been challenging to collect the required environmental data to study thermoregulation of free-ranging mammals such as mantled howling monkeys (Alouatta palliata). Fortunately, recent advances in fiber-optic distributed temperature sensing (DTS) now permit the observation of temperature fields in the environment at scales ranging from millimeters to kilometers. This has opened an exciting opportunity for temperature monitoring at scales that were previously not feasible. This study addresses the main limitations of previous studies of primate behavior by integrating real-time environmental data with the behavior and physiological response of free-ranging primates. In this work, we present preliminary DTS data collected in a natural habitat of howling monkeys. Fiber-optic cables were hung between the ground and an elevation of approximately 15 m within the forest canopy, providing continuous profiles of temperature without any disturbance due to the animals and habitat. These measurements were integrated with conventional meteorological data and with the ambient temperature at the location of the animal, as well as with measurements of primate's subcutaneous and core body temperatures. These data will be utilized to determine how environmental conditions relate to primate behavioral and physiological responses in time and space. The methodologies used in this study provide tools to test theories of physiological thermoregulation of other free-ranging animals.

  20. Normal range and lateral symmetry in the skin temperature profile of pregnant women

    NASA Astrophysics Data System (ADS)

    Pereira, Tânia; Nogueira-Silva, Cristina; Simoes, Ricardo

    2016-09-01

    Body skin temperature is a useful parameter for diagnosing diseases and infrared thermography can be a powerful tool in providing important information to detect body temperature changes in a noninvasive way. The aim of this work was to study the pattern of skin temperature during pregnancy, to establish skin temperature reference values and to find correlations between these and the pregnant population characteristics. Sixty-one healthy pregnant women (mean age 30.6 ± 5.1 years) in the 8th-40th gestational week with normal pregnancies were examined in 31 regions of interest (ROI). The ROIs were defined all over the body in order to determine the most influenced by factors such as age or body mass index (BMI). The results obtained in this work highlight that in normal pregnant women the skin temperature is symmetrically distributed, with the symmetrical areas differing less than 0.5 °C , with a mean value of 0.25 ± 0.23 °C . This study identified a significant negative correlation between the BMI and temperature. Age has been shown to have great influence on the skin temperature, with a significant increase of temperature observed with age. This work explores a novel medical application of infrared thermography and provides a characterization of thermal skin profile in human pregnancy for a large set of ROIs while also evaluating the effects of age and BMI.

  1. Spatial and Temporal Stream Temperature Response to Contemporary Forest Harvesting in the Oregon Coast Range

    NASA Astrophysics Data System (ADS)

    Bladon, K. D.; Cook, N. A.; Light, J. T.; Segura, C.; Teply, M.

    2015-12-01

    Historical research at the Alsea Watershed Study (1958-1973), in the Oregon Coast Range, demonstrated that clear-cut harvesting, with complete removal of riparian vegetation, can result in large and dramatic changes in mean daily, maximum daily, diurnal variation, and annual patterns in stream temperature (Ts). This previous research was instrumental in the addition of regulations in the Oregon Forest Practices Act of 1971, necessitating retention of streamside vegetation (riparian management zones) in harvest units to maintain water quality and aquatic habitat. Due to the ecological importance of Ts, preventing or mitigating changes in the thermal regime following land use activities, such as forest harvesting, is a primary focus of contemporary forest watershed management. The Alsea Watershed Study Revisited (2006-Present) has provided a unique opportunity to investigate the Ts responses to contemporary forest harvesting practices and compare these with the impacts from the 1960's harvest. In general, Ts increases from late spring through about mid-July, with peak Ts occuring between about mid-July and mid-August, after which Ts decreases into the fall. During the pre-harvest period (2006-2008; n=244) the June to September mean daily maximum Ts was 13.0°C in Flynn Creek (control) and 12.0°C in Needle Branch (harvested). In the post-harvest period (2010-2012; n=240) the June to September mean daily maximum Ts was 12.4°C in Flynn Creek (control) and 12.0°C in Needle Branch (harvested). Similarly, the difference (Flynn Ck - Needle Branch) in 7 day moving mean of daily maximum Ts decreased from the pre-harvest (1.0°C) to the post-harvest (0.3°C) period, which was principally driven by a decrease in Ts in the control catchment. Longitudinal sampling of Ts within Needle Branch indicated a cooling trend such that the slight increases in post-harvest Ts weren't detectable in downstream, unharvested stream reaches.

  2. Relaxation dynamics of glasses along a wide stability and temperature range

    PubMed Central

    Rodríguez-Tinoco, C.; Ràfols-Ribé, J.; González-Silveira, M.; Rodríguez-Viejo, J.

    2016-01-01

    While lots of measurements describe the relaxation dynamics of the liquid state, experimental data of the glass dynamics at high temperatures are much scarcer. We use ultrafast scanning calorimetry to expand the timescales of the glass to much shorter values than previously achieved. Our data show that the relaxation time of glasses follows a super-Arrhenius behaviour in the high-temperature regime above the conventional devitrification temperature heating at 10 K/min. The liquid and glass states can be described by a common VFT-like expression that solely depends on temperature and limiting fictive temperature. We apply this common description to nearly-isotropic glasses of indomethacin, toluene and to recent data on metallic glasses. We also show that the dynamics of indomethacin glasses obey density scaling laws originally derived for the liquid. This work provides a strong connection between the dynamics of the equilibrium supercooled liquid and non-equilibrium glassy states. PMID:27767071

  3. On the Trend of the Annual Mean, Maximum, and Minimum Temperature and the Diurnal Temperature Range in the Armagh Observatory, Northern Ireland, Dataset, 1844 -2012

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2013-01-01

    Examined are the annual averages, 10-year moving averages, decadal averages, and sunspot cycle (SC) length averages of the mean, maximum, and minimum surface air temperatures and the diurnal temperature range (DTR) for the Armagh Observatory, Northern Ireland, during the interval 1844-2012. Strong upward trends are apparent in the Armagh surface-air temperatures (ASAT), while a strong downward trend is apparent in the DTR, especially when the ASAT data are averaged by decade or over individual SC lengths. The long-term decrease in the decadaland SC-averaged annual DTR occurs because the annual minimum temperatures have risen more quickly than the annual maximum temperatures. Estimates are given for the Armagh annual mean, maximum, and minimum temperatures and the DTR for the current decade (2010-2019) and SC24.

  4. Rapid freezing injury in red spruce: seasonal changes in sensitivity and effects of temperature range.

    PubMed

    Strimbeck, G. R.; DeHayes, D. H.

    2000-02-01

    On calm, cold days in winter, sun-exposed needles of red spruce (Picea rubens Sarg.) may warm 10 to 20 degrees C above ambient air temperature, and undergo rapid (>/= 1 degrees C min(-1)) fluctuations in temperature as light breezes or passing clouds alter the energy balance of the foliage. It has been proposed that the resulting rapid freeze-thaw cycles (freezing stress) cause a type of winter injury in montane red spruce that is characterized by necrosis of sun-exposed foliage. In autumn and winter, we monitored rapid freezing stress response of needle sections from 10 montane red spruce trees by subjecting needles to rapid freezing over the temperature span typically recorded in the field. In autumn, experimental rapid freezing stress produced severe injury only at temperatures considerably lower than expected for that time of year. In winter, rapid freezing caused occasional, moderate injury in fully hardened foliage of trees susceptible to both slow and rapid freezing. Seasonal changes in sensitivity to rapid and slow freezing were correlated, suggesting that environmental factors that are known to affect sensitivity to slow freezing may also affect sensitivity to rapid freezing. Experimental manipulation of the start and end temperatures of rapid freezing stress events showed that moderate to severe needle injury can occur in susceptible trees at temperature spans slightly more extreme than those typically recorded in the field. The extent of injury was similar at different starting temperatures if rapid freezing occurred over the same temperature span. Year-old foliage was consistently less sensitive to rapid freezing stress than current-year foliage, but some year-old foliage was damaged when the rapid freezing stress regime caused severe injury in current-year foliage. We conclude that rapid freeze-thaw cycles can explain light to moderate injury of current-year foliage, but they do not explain the more severe and widespread pattern of foliar damage that

  5. Environmental temperatures, physiology and behavior limit the range expansion of invasive Burmese pythons in southeastern USA.

    PubMed

    Jacobson, Elliott R; Barker, David G; Barker, Tracy M; Mauldin, Richard; Avery, Michael L; Engeman, Richard; Secor, Stephen

    2012-09-01

    A well-established population of Burmese pythons resides in the Everglades of southern Florida. Prompted in part by a report that identified much of southern USA as suitable habitat for expansion or establishment of the Burmese python, we examined the plausibility of this snake to survive winters at sites north of the Everglades. We integrated daily low and high temperatures recorded from October to February from 2005-2011 at Homestead, Orlando and Gainesville, Florida; and Aiken, South Carolina, with minimum temperatures projected for python digestion (16 °C), activity (5 °C) and survival (0 °C). Mean low and high temperatures decreased northward from Homestead to Aiken and the number of days of freezing temperatures increased northward. Digestion was impaired or inhibited for 2 months in the Everglades and up to at least 5 months in Aiken, and activity was increasingly limited northward during these months. Reports of overwinter survivorship document that a single bout of low and freezing temperatures results in python death. The capacity for Burmese pythons to successfully overwinter in more temperate regions of the USA is seemingly prohibited because they lack the behaviors to seek refuge from, and the physiology to tolerate, cold temperatures. As tropical Southeast Asia is the source of the Everglades Burmese pythons, we predict it is unlikely that they will be able to successfully expand to or colonize more temperate areas of Florida and adjoining states due to their lack of behavioral and physiological traits to seek refuge from cold temperatures. PMID:22938524

  6. Thermal Expansion of NaZr2(PO4)3 Family Ceramics in a Low-Temperature Range

    NASA Astrophysics Data System (ADS)

    Miyazaki, Hidetoshi; Ushiroda, Isao; Itomura, Daisuke; Hirashita, Tsunehisa; Adachi, Nobuyasu; Ota, Toshitaka

    2008-09-01

    NZP family ceramics - NaZr2(PO4)3 (NZP), KZr2(PO4)3, RbZr2(PO4)3, Cs Zr2(PO4)3, CaZr4(PO4)6, SrZr4(PO4)6 (SrZP), and BaZr4(PO4)6 - were synthesized by a solid-state reaction, and their thermal expansion properties were investigated by X-ray diffraction measurement in a temperature range of -150 to 250 °C. The increases in the average thermal expansion coefficients of all the NZP family ceramics in this low temperature range (-150 to 250 °C) were smaller than those in a high temperature range (room temperature to 1000 °C). The thermal expansion coefficient of the SrZP ceramic was 0.2×10-6/°C between -150 to 250 °C, which is very small. This proved that SrZP has a near-zero thermal expansion coefficient in a low-temperature range.

  7. The impact of temperature on the bionomics of Aedes (Stegomyia) aegypti, with special reference to the cool geographic range margins.

    PubMed

    Eisen, Lars; Monaghan, Andrew J; Lozano-Fuentes, Saul; Steinhoff, Daniel F; Hayden, Mary H; Bieringer, Paul E

    2014-05-01

    The mosquito Aedes (Stegomyia) aegypti (L.), which occurs widely in the subtropics and tropics, is the primary urban vector of dengue and yellow fever viruses, and an important vector of chikungunya virus. There is substantial interest in how climate change may impact the bionomics and pathogen transmission potential of this mosquito. This Forum article focuses specifically on the effects of temperature on the bionomics of Ae. aegypti, with special emphasis on the cool geographic range margins where future rising temperatures could facilitate population growth. Key aims are to: 1) broadly define intra-annual (seasonal) patterns of occurrence and abundance of Ae. aegypti, and their relation to climate conditions; 2) synthesize the existing quantitative knowledge of how temperature impacts the bionomics of different life stages of Ae. aegypti; 3) better define the temperature ranges for which existing population dynamics models for Ae. aegypti are likely to produce robust predictions; 4) explore potential impacts of climate warming on human risk for exposure to Ae. aegypti at its cool range margins; and 5) identify knowledge or data gaps that hinder our ability to predict risk of human exposure to Ae. aegypti at the cool margins of its geographic range now and in the future. We first outline basic scenarios for intra-annual occurrence and abundance patterns for Ae. aegypti, and then show that these scenarios segregate with regard to climate conditions in selected cities where they occur. We then review how near-constant and intentionally fluctuating temperatures impact development times and survival of eggs and immatures. A subset of data, generated in controlled experimental studies, from the published literature is used to plot development rates and survival of eggs, larvae, and pupae in relation to water temperature. The general shape of the relationship between water temperature and development rate is similar for eggs, larvae, and pupae. Once the lower

  8. The impact of temperature on the bionomics of Aedes (Stegomyia) aegypti, with special reference to the cool geographic range margins.

    PubMed

    Eisen, Lars; Monaghan, Andrew J; Lozano-Fuentes, Saul; Steinhoff, Daniel F; Hayden, Mary H; Bieringer, Paul E

    2014-05-01

    The mosquito Aedes (Stegomyia) aegypti (L.), which occurs widely in the subtropics and tropics, is the primary urban vector of dengue and yellow fever viruses, and an important vector of chikungunya virus. There is substantial interest in how climate change may impact the bionomics and pathogen transmission potential of this mosquito. This Forum article focuses specifically on the effects of temperature on the bionomics of Ae. aegypti, with special emphasis on the cool geographic range margins where future rising temperatures could facilitate population growth. Key aims are to: 1) broadly define intra-annual (seasonal) patterns of occurrence and abundance of Ae. aegypti, and their relation to climate conditions; 2) synthesize the existing quantitative knowledge of how temperature impacts the bionomics of different life stages of Ae. aegypti; 3) better define the temperature ranges for which existing population dynamics models for Ae. aegypti are likely to produce robust predictions; 4) explore potential impacts of climate warming on human risk for exposure to Ae. aegypti at its cool range margins; and 5) identify knowledge or data gaps that hinder our ability to predict risk of human exposure to Ae. aegypti at the cool margins of its geographic range now and in the future. We first outline basic scenarios for intra-annual occurrence and abundance patterns for Ae. aegypti, and then show that these scenarios segregate with regard to climate conditions in selected cities where they occur. We then review how near-constant and intentionally fluctuating temperatures impact development times and survival of eggs and immatures. A subset of data, generated in controlled experimental studies, from the published literature is used to plot development rates and survival of eggs, larvae, and pupae in relation to water temperature. The general shape of the relationship between water temperature and development rate is similar for eggs, larvae, and pupae. Once the lower

  9. Defining torpor in free-ranging bats: experimental evaluation of external temperature-sensitive radiotransmitters and the concept of active temperature.

    PubMed

    Willis, C K R; Brigham, R M

    2003-07-01

    A variety of definitions involving body temperature (Tb), metabolic rate and behavior have been used to define torpor in mammals and birds. This problem is confounded in some studies of free-ranging animals that employ only skin temperature (Tsk), a measure that approximates but may not precisely reflect Tb. We assess the accuracy of Tsk in the context of a recent definition for torpor called active temperature. We compared the active temperatures of individual big brown bats (Eptesicus fuscus), which aggregate in cavities, with solitary, foliage-roosting hoary bats (Lasiurus cinereus). In captive big brown bats, we compared Tsk and core Tb at a range of ambient temperatures for clustered and solitary roosting animals, compared Tsk and Tb during arousal from torpor, and quantified the effect of flight on warming from torpor. Hoary bats had significantly lower active temperatures than big brown bats despite having the same normothermic Tsk. Tsk was significantly lower than Tb during normothermia but often greater than Tb during torpor. Flight increased the rate of warming from torpor. This effect was more pronounced for Tsk than Tb. This suggests that bats could rely on heat generated by flight muscles to complete the final stages of arousal. Using active temperature to define torpor may underestimate torpor due to ambient cooling of external transmitters or animals leaving roosts while still torpid. Conversely, active temperature may also overestimate shallow torpor use if it is recorded during active arousal when shivering and non-shivering thermogenesis warm external transmitters. Our findings illuminate the need for laboratory studies that quantify the relationship between metabolic rate and Tsk over a range of ambient temperatures. PMID:12764630

  10. Fast acclimation of freezing resistance suggests no influence of winter minimum temperature on the range limit of European beech.

    PubMed

    Lenz, Armando; Hoch, Günter; Vitasse, Yann

    2016-04-01

    Low temperature extremes drive species distribution at a global scale. Here, we assessed the acclimation potential of freezing resistance in European beech (Fagus sylvaticaL.) during winter. We specifically asked (i) how do beech populations growing in contrasting climates differ in their maximum freezing resistance, (ii) do differences result from genetic differentiation or phenotypic plasticity to preceding temperatures and (iii) is beech at risk of freezing damage in winter across its distribution range. We investigated the genetic and environmental components of freezing resistance in buds of adult beech trees from three different populations along a natural large temperature gradient in north-western Switzerland, including the site holding the cold temperature record in Switzerland. Freezing resistance of leaf primordia in buds varied significantly among populations, with LT50values (lethal temperature for 50% of samples) ranging from -25 to -40 °C, correlating with midwinter temperatures of the site of origin. Cambial meristems and the pith of shoots showed high freezing resistance in all three populations, with only a trend to lower freezing resistance at the warmer site. After hardening samples at -6 °C for 5 days, freezing resistance of leaf primordia increased in all provenances by up to 4.5 K. After additional hardening at -15 °C for 3 days, all leaf primordia were freezing resistant to -40 °C. We demonstrate that freezing resistance ofF. sylvaticahas a high ability to acclimate to temperature changes in winter, whereas the genetic differentiation of freezing resistance among populations seems negligible over this small geographic scale but large climatic gradient. In contrast to the assumption made in most of the species distribution models, we suggest that absolute minimum temperature in winter is unlikely to shape the cold range limit of beech. We conclude that the rapid acclimation of freezing resistance to winter temperatures allows

  11. The potential for climate-driven bathymetric range shifts: sustained temperature and pressure exposures on a marine ectotherm, Palaemonetes varians

    PubMed Central

    Morris, J. P.; Thatje, S.; Cottin, D.; Oliphant, A.; Brown, A.; Shillito, B.; Ravaux, J.; Hauton, C.

    2015-01-01

    Range shifts are of great importance as a response for species facing climate change. In the light of current ocean-surface warming, many studies have focused on the capacity of marine ectotherms to shift their ranges latitudinally. Bathymetric range shifts offer an important alternative, and may be the sole option for species already at high latitudes or those within enclosed seas; yet relevant data are scant. Hydrostatic pressure (HP) and temperature have wide ranging effects on physiology, importantly acting in synergy thermodynamically, and therefore represent key environmental constraints to bathymetric migration. We present data on transcriptional regulation in a shallow-water marine crustacean (Palaemonetes varians) at atmospheric and high HP following 168-h exposures at three temperatures across the organisms’ thermal scope, to establish the potential physiological limit to bathymetric migration by neritic fauna. We observe changes in gene expression indicative of cellular macromolecular damage, disturbances in metabolic pathways and a lack of acclimation after prolonged exposure to high HP. Importantly, these effects are ameliorated (less deleterious) at higher temperatures, and exacerbated at lower temperatures. These data, alongside previously published behavioural and heat-shock analyses, have important implications for our understanding of the potential for climate-driven bathymetric range shifts PMID:26716003

  12. Modified shape memory cyanate polymers with a wide range of high glass transition temperatures

    NASA Astrophysics Data System (ADS)

    Xie, Fang; Huang, Longnan; Liu, Yanju; Leng, Jinsong

    2012-04-01

    Shape memory cyanate polymers (SMCPs) are a new kind of smart materials, which have huge development potential and a promising future. A series of shape memory cyanate polymers were prepared by cyanate ester and varying content of a linear modifier. The thermal properties of the SMCPs were investigated by Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA). The SMCPs we prepared have high glass transition temperature and show good heat resistance. The glass transition temperature Tg can be adjusted from 156.9°C to 259.6°C with the modifier. The initial temperature of thermal decomposition comes up to 300°C, which is enough high for the application in aerospace fields. The shape memory polymer we prepared shows a good shape memory effect, as the shape recovery time is less than 65s and the shape recovery rate reaches 95%.

  13. The dynamical mechanical properties of tungsten under compression at working temperature range of divertors

    NASA Astrophysics Data System (ADS)

    Zhu, C. C.; Song, Y. T.; Peng, X. B.; Wei, Y. P.; Mao, X.; Li, W. X.; Qian, X. Y.

    2016-02-01

    In the divertor structure of ITER and EAST with mono-block module, tungsten plays not only a role of armor material but also a role of structural material, because electromagnetic (EM) impact will be exerted on tungsten components in VDEs or CQ. The EM loads can reach to 100 MN, which would cause high strain rates. In addition, directly exposed to high-temperature plasma, the temperature regime of divertor components is complex. Aiming at studying dynamical response of tungsten divertors under EM loads, an experiment on tungsten employed in EAST divertors was performed using a Kolsky bar system. The testing strain rates and temperatures is derived from actual working conditions, which makes the constitutive equation concluded by using John-Cook model and testing data very accurate and practical. The work would give a guidance to estimate the dynamical response, fatigue life and damage evolution of tungsten divertor components under EM impact loads.

  14. Stability of cable thermocouples at the upper temperature limit of their working range

    NASA Astrophysics Data System (ADS)

    Ulanovskiy, A. A.; Zemba, E. S.; Belenkiy, A. M.; Chibizova, S. I.; Bursin, A. N.

    2013-09-01

    Experimental results of EMF stability research are presented for MIMS thermocouples of types K and N of external diameters 1.5; 3.0 and 5.0 mm. All thermocouples had heat resistant sheath and were not used before the tests. They were subjected to every-day cyclic heating and cooling. During each cycle there was 6 h annealing in air at the temperature 1200 °C Results shows, that stability of a cable thermocouple in air at the temperature 1200 °C depends, mainly, on its diameter, instead of on thermocouple type or metal sheath material. Acceptable time of operation in a thermal cycling mode for 1.5 mm cable thermocouples is limited by (15, 16) h, and for 3 mm thermocouples it is equal to (40, 45) h. Besides, the effect of signal shunting is shown in the work for a thermocouple under heating of its average part to the temperature 1200 °C Experiment has shown that use of long cable thermocouple of 1.5 mm diameter at the temperatures above 1000°C can lead to serious errors in temperature measurement. Heating of 400 mm thermocouple length to 1100 °C causes positive EMF in the 1.5 mm cable thermocouple equivalent to +3.4 °C and +18 °C at 1200°C. For 3 mm cable thermocouple EMF at 1200 °C reaches the value equivalent to +2.3 °C, but double increase in heating length makes the value greater to +13.5 °C. The given facts are necessary to consider while using of thin (1, 3) mm cable thermocouples at the temperatures (1100, 1200) °C.

  15. Reduced diurnal temperature range does not change warming impacts on ecosystem carbon balance of Mediterranean grassland mesocosms

    SciTech Connect

    Phillips, Claire L.; Gregg, Jillian W.; Wilson, John K.

    2011-11-01

    Daily minimum temperature (Tmin) has increased faster than daily maximum temperature (Tmax) in many parts of the world, leading to decreases in diurnal temperature range (DTR). Projections suggest these trends are likely to continue in many regions, particularly northern latitudes and in arid regions. Despite wide speculation that asymmetric warming has different impacts on plant and ecosystem production than equal-night-and-day warming, there has been little direct comparison of these scenarios. Reduced DTR has also been widely misinterpreted as a result of night-only warming, when in fact Tmin occurs near dawn, indicating higher morning as well as night temperatures. We report on the first experiment to examine ecosystem-scale impacts of faster increases in Tmin than Tmax, using precise temperature controls to create realistic diurnal temperature profiles with gradual day-night temperature transitions and elevated early morning as well as night temperatures. Studying a constructed grassland ecosystem containing species native to Oregon, USA, we found the ecosystem lost more carbon at elevated than ambient temperatures, but was unaffected by the 3ºC difference in DTR between symmetric warming (constantly ambient +3.5ºC) and asymmetric warming (dawn Tmin=ambient +5ºC, afternoon Tmax= ambient +2ºC). Reducing DTR had no apparent effect on photosynthesis, likely because temperatures were most different in the morning and late afternoon when light was low. Respiration was also similar in both warming treatments, because respiration temperature sensitivity was not sufficient to respond to the limited temperature differences between asymmetric and symmetric warming. We concluded that changes in daily mean temperatures, rather than changes in Tmin/Tmax, were sufficient for predicting ecosystem carbon fluxes in this reconstructed Mediterranean grassland system.

  16. Reduced diurnal temperature range does not change warming impacts on ecosystem carbon balance of Mediterranean grassland mesocosms

    DOE PAGES

    Phillips, Claire L.; Gregg, Jillian W.; Wilson, John K.

    2011-11-01

    Daily minimum temperature (Tmin) has increased faster than daily maximum temperature (Tmax) in many parts of the world, leading to decreases in diurnal temperature range (DTR). Projections suggest these trends are likely to continue in many regions, particularly northern latitudes and in arid regions. Despite wide speculation that asymmetric warming has different impacts on plant and ecosystem production than equal-night-and-day warming, there has been little direct comparison of these scenarios. Reduced DTR has also been widely misinterpreted as a result of night-only warming, when in fact Tmin occurs near dawn, indicating higher morning as well as night temperatures. We reportmore » on the first experiment to examine ecosystem-scale impacts of faster increases in Tmin than Tmax, using precise temperature controls to create realistic diurnal temperature profiles with gradual day-night temperature transitions and elevated early morning as well as night temperatures. Studying a constructed grassland ecosystem containing species native to Oregon, USA, we found the ecosystem lost more carbon at elevated than ambient temperatures, but was unaffected by the 3ºC difference in DTR between symmetric warming (constantly ambient +3.5ºC) and asymmetric warming (dawn Tmin=ambient +5ºC, afternoon Tmax= ambient +2ºC). Reducing DTR had no apparent effect on photosynthesis, likely because temperatures were most different in the morning and late afternoon when light was low. Respiration was also similar in both warming treatments, because respiration temperature sensitivity was not sufficient to respond to the limited temperature differences between asymmetric and symmetric warming. We concluded that changes in daily mean temperatures, rather than changes in Tmin/Tmax, were sufficient for predicting ecosystem carbon fluxes in this reconstructed Mediterranean grassland system.« less

  17. Estimates of the difference between thermodynamic temperature and the International Temperature Scale of 1990 in the range 118 K to 303 K.

    PubMed

    Underwood, R; de Podesta, M; Sutton, G; Stanger, L; Rusby, R; Harris, P; Morantz, P; Machin, G

    2016-03-28

    Using exceptionally accurate measurements of the speed of sound in argon, we have made estimates of the difference between thermodynamic temperature, T, and the temperature estimated using the International Temperature Scale of 1990, T90, in the range 118 K to 303 K. Thermodynamic temperature was estimated using the technique of relative primary acoustic thermometry in the NPL-Cranfield combined microwave and acoustic resonator. Our values of (T-T90) agree well with most recent estimates, but because we have taken data at closely spaced temperature intervals, the data reveal previously unseen detail. Most strikingly, we see undulations in (T-T90) below 273.16 K, and the discontinuity in the slope of (T-T90) at 273.16 K appears to have the opposite sign to that previously reported. PMID:26903104

  18. Electrocaloric properties of ferroelectric-paraelectric superlattices controlled by the thickness of paraelectric layer in a wide temperature range

    SciTech Connect

    Ma, D. C.; Lin, S. P.; Chen, W. J.; Zheng, Yue Xiong, W. M.; Wang, Biao

    2014-10-15

    As functions of the paraelectric layer thickness, misfit strain and temperature, the electrocaloric properties of ferroelectric-paraelectric superlattices are investigated using a time-dependent Ginzburg-Landau thermodynamic model. Ferroelectric phase transition driven by the relative thickness of the superlattice is found to dramatically impact the electrocaloric response. Near the phase transition temperature, the magnitude of the electrocaloric effect is maximized and shifted to lower temperatures by increasing the relative thickness of paraelectric layer. Theoretical calculations also imply that the electrocaloric effect of the superlattices depends not only on the relative thickness of paraelectric layer but also on misfit strain. Furthermore, control of the relative thickness of paraelectric layer and the misfit strain can change availably both the magnitude and the temperature sensitivity of the electrocaloric effect, which suggests that ferroelectric-paraelectric superlattices may be promising candidates for use in cooling devices in a wide temperature range.

  19. All-solid-state lithium-oxygen battery with high safety in wide ambient temperature range

    NASA Astrophysics Data System (ADS)

    Kitaura, Hirokazu; Zhou, Haoshen

    2015-08-01

    There is need to develop high energy storage devices with high safety to satisfy the growing industrial demands. Here, we show the potential to realize such batteries by assembling a lithium-oxygen cell using an inorganic solid electrolyte without any flammable liquid or polymer materials. The lithium-oxygen battery using Li1.575Al0.5Ge1.5(PO4)3 solid electrolyte was examined in the pure oxygen atmosphere from room temperature to 120 °C. The cell works at room temperature and first full discharge capacity of 1420 mAh g-1 at 10 mA g-1 (based on the mass of carbon material in the air electrode) was obtained. The charge curve started from 3.0 V, and that the majority of it lay below 4.2 V. The cell also safely works at high temperature over 80 °C with the improved battery performance. Furthermore, fundamental data of the electrochemical performance, such as cyclic voltammogram, cycle performance and rate performance was obtained and this work demonstrated the potential of the all-solid-state lithium-oxygen battery for wide temperature application as a first step.

  20. All-solid-state lithium-oxygen battery with high safety in wide ambient temperature range

    PubMed Central

    Kitaura, Hirokazu; Zhou, Haoshen

    2015-01-01

    There is need to develop high energy storage devices with high safety to satisfy the growing industrial demands. Here, we show the potential to realize such batteries by assembling a lithium-oxygen cell using an inorganic solid electrolyte without any flammable liquid or polymer materials. The lithium-oxygen battery using Li1.575Al0.5Ge1.5(PO4)3 solid electrolyte was examined in the pure oxygen atmosphere from room temperature to 120 °C. The cell works at room temperature and first full discharge capacity of 1420 mAh g−1 at 10 mA g−1 (based on the mass of carbon material in the air electrode) was obtained. The charge curve started from 3.0 V, and that the majority of it lay below 4.2 V. The cell also safely works at high temperature over 80 °C with the improved battery performance. Furthermore, fundamental data of the electrochemical performance, such as cyclic voltammogram, cycle performance and rate performance was obtained and this work demonstrated the potential of the all-solid-state lithium-oxygen battery for wide temperature application as a first step. PMID:26293134

  1. Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range.

    PubMed

    Wu, Xiaojun; Zhou, Chun; Huang, Wenqian Ronny; Ahr, Frederike; Kärtner, Franz X

    2015-11-16

    Optical rectification with tilted pulse fronts in lithium niobate crystals is one of the most promising methods to generate terahertz (THz) radiation. In order to achieve higher optical-to-THz energy efficiency, it is necessary to cryogenically cool the crystal not only to decrease the linear phonon absorption for the generated THz wave but also to lengthen the effective interaction length between infrared pump pulses and THz waves. However, the refractive index of lithium niobate crystal at lower temperature is not the same as that at room temperature, resulting in the necessity to re-optimize or even re-build the tilted pulse front setup. Here, we performed a temperature dependent measurement of refractive index and absorption coefficient on a 6.0 mol% MgO-doped congruent lithium niobate wafer by using a THz time-domain spectrometer (THz-TDS). When the crystal temperature was decreased from 300 K to 50 K, the refractive index of the crystal in the extraordinary polarization decreased from 5.05 to 4.88 at 0.4 THz, resulting in ~1° change for the tilt angle inside the lithium niobate crystal. The angle of incidence on the grating for the tilted pulse front setup at 1030 nm with demagnification factor of -0.5 needs to be changed by 3°. The absorption coefficient decreased by 60% at 0.4 THz. These results are crucial for designing an optimum tilted pulse front setup based on lithium niobate crystals.

  2. All-solid-state lithium-oxygen battery with high safety in wide ambient temperature range.

    PubMed

    Kitaura, Hirokazu; Zhou, Haoshen

    2015-08-21

    There is need to develop high energy storage devices with high safety to satisfy the growing industrial demands. Here, we show the potential to realize such batteries by assembling a lithium-oxygen cell using an inorganic solid electrolyte without any flammable liquid or polymer materials. The lithium-oxygen battery using Li1.575Al0.5Ge1.5(PO4)3 solid electrolyte was examined in the pure oxygen atmosphere from room temperature to 120 °C. The cell works at room temperature and first full discharge capacity of 1420 mAh g(-1) at 10 mA g(-1) (based on the mass of carbon material in the air electrode) was obtained. The charge curve started from 3.0 V, and that the majority of it lay below 4.2 V. The cell also safely works at high temperature over 80 °C with the improved battery performance. Furthermore, fundamental data of the electrochemical performance, such as cyclic voltammogram, cycle performance and rate performance was obtained and this work demonstrated the potential of the all-solid-state lithium-oxygen battery for wide temperature application as a first step.

  3. All-solid-state lithium-oxygen battery with high safety in wide ambient temperature range.

    PubMed

    Kitaura, Hirokazu; Zhou, Haoshen

    2015-01-01

    There is need to develop high energy storage devices with high safety to satisfy the growing industrial demands. Here, we show the potential to realize such batteries by assembling a lithium-oxygen cell using an inorganic solid electrolyte without any flammable liquid or polymer materials. The lithium-oxygen battery using Li1.575Al0.5Ge1.5(PO4)3 solid electrolyte was examined in the pure oxygen atmosphere from room temperature to 120 °C. The cell works at room temperature and first full discharge capacity of 1420 mAh g(-1) at 10 mA g(-1) (based on the mass of carbon material in the air electrode) was obtained. The charge curve started from 3.0 V, and that the majority of it lay below 4.2 V. The cell also safely works at high temperature over 80 °C with the improved battery performance. Furthermore, fundamental data of the electrochemical performance, such as cyclic voltammogram, cycle performance and rate performance was obtained and this work demonstrated the potential of the all-solid-state lithium-oxygen battery for wide temperature application as a first step. PMID:26293134

  4. Range-wide latitudinal and elevational temperature gradients for the world's terrestrial birds: implications under global climate change.

    PubMed

    La Sorte, Frank A; Butchart, Stuart H M; Jetz, Walter; Böhning-Gaese, Katrin

    2014-01-01

    Species' geographical distributions are tracking latitudinal and elevational surface temperature gradients under global climate change. To evaluate the opportunities to track these gradients across space, we provide a first baseline assessment of the steepness of these gradients for the world's terrestrial birds. Within the breeding ranges of 9,014 bird species, we characterized the spatial gradients in temperature along latitude and elevation for all and a subset of bird species, respectively. We summarized these temperature gradients globally for threatened and non-threatened species and determined how their steepness varied based on species' geography (range size, shape, and orientation) and projected changes in temperature under climate change. Elevational temperature gradients were steepest for species in Africa, western North and South America, and central Asia and shallowest in Australasia, insular IndoMalaya, and the Neotropical lowlands. Latitudinal temperature gradients were steepest for extratropical species, especially in the Northern Hemisphere. Threatened species had shallower elevational gradients whereas latitudinal gradients differed little between threatened and non-threatened species. The strength of elevational gradients was positively correlated with projected changes in temperature. For latitudinal gradients, this relationship only held for extratropical species. The strength of latitudinal gradients was better predicted by species' geography, but primarily for extratropical species. Our findings suggest threatened species are associated with shallower elevational temperature gradients, whereas steep latitudinal gradients are most prevalent outside the tropics where fewer bird species occur year-round. Future modeling and mitigation efforts would benefit from the development of finer grain distributional data to ascertain how these gradients are structured within species' ranges, how and why these gradients vary among species, and the capacity

  5. Long range forecasts of the Northern Hemisphere anomalies with antecedent sea surface temperature patterns

    NASA Technical Reports Server (NTRS)

    Kung, Ernest C.

    1994-01-01

    The contract research has been conducted in the following three major areas: analysis of numerical simulations and parallel observations of atmospheric blocking, diagnosis of the lower boundary heating and the response of the atmospheric circulation, and comprehensive assessment of long-range forecasting with numerical and regression methods. The essential scientific and developmental purpose of this contract research is to extend our capability of numerical weather forecasting by the comprehensive general circulation model. The systematic work as listed above is thus geared to developing a technological basis for future NASA long-range forecasting.

  6. Comparison of calculated and experimental thermal attachment rate constants for SF6 in the temperature range 200-600 K

    NASA Technical Reports Server (NTRS)

    Orient, O. J.; Chutjian, A.

    1986-01-01

    Electron-attachment cross sections are calcualted for the process e(-) + SF6 yields SF6(-) in the energy range 1-200 meV. An electron scattering approximation is used in which diatomiclike potential energy curves near the equilibrium SF6 ground state are constructed from recent spectroscopic data. Excellent agreement is found over the entire energy range with experimental attachment cross sections at a temperature of 300 K for s-wave (l = 0) scattering. The same calculation, with appropriate adjustment of the thermal populations, is used to calculate attachment rate constants in the range 50-600 K for both s- and p-wave scattering.

  7. Analysis of Er{sup 3+} and Ho{sup 3+} codoped fluoroindate glasses as wide range temperature sensor

    SciTech Connect

    Haro-Gonzalez, P.

    2011-07-15

    Graphical abstract: The sensor sensitivity as a function of the temperature of erbium and holmium doped fluoroindate glasses. A wide temperature range from 20 K to 425 K is covered with a sensitivity larger than 0.0005. Highlights: {yields} The FIR technique has been carried out in fluoroindate glass sample. {yields} The Er doped fluoroindate sample has a maximum sensitivity of 0.0028 K{sup -1} at 425 K. {yields} The Ho doped fluoroindate sample has a maximum sensitivity of 0.0036 K{sup -1} at 59 K. -- Abstract: The fluorescence intensity ratio technique for two fluoroindate glass samples has been carried out. The green emissions at 523 nm and at 545 nm in a 0.1 mol% of Er{sup 3+} doped fluoroindate glass was studied in a wide range of temperature from 125 K to 425 K with a maximum sensitivity of 0.0028 K{sup -1} for 425 K. In a sample doped with 0.1 mol% of Ho{sup 3+} the emissions at 545 nm and at 750 nm were analyzed as a function of temperature from 20 K to 300 K obtaining a maximum sensitivity of 0.0036 K{sup -1} at 59 K. Using both fluoroindate glass samples a wide temperature range from 20 K to 425 K is easily covered pumping with two low-cost diode laser at 406 nm and 473 nm.

  8. Study of the Spectral Properties of Nanocomposites with CdSe Quantum Dots in a Wide Range of Low Temperatures

    NASA Astrophysics Data System (ADS)

    Magaryan, K. A.; Eremchev, I. Y.; Karimullin, K. R.; Knyazev, M. V.; Mikhailov, M. A.; Vasilieva, I. A.; Klimusheva, G. V.

    2015-09-01

    Luminescence spectra of the colloidal solution of CdSe quantum dots (in toluene) were studied in a wide range of low temperatures. Samples were synthesized in the liquid crystal matrix of cadmium octanoate (CdC8). A comparative analysis of the obtained data with previous results was performed.

  9. Calculation of the density of solutions (sunflower oil + n-hexane) over a wide range of temperatures and pressure

    NASA Astrophysics Data System (ADS)

    Safarov, M. M.; Abdukhamidova, Z.

    1995-09-01

    We present the results from an experimental investigation of the density of the sunflower oil system as a function of the mass concentration of n-hexane in the ranges of temperatures T=290 520 K and pressures P=0.101 98.1 MPa. A method of hydrostatic weighing was used to measure the density of the solutions under study.

  10. Novel iron titanate catalyst for the selective catalytic reduction of NO with NH3 in the medium temperature range.

    PubMed

    Liu, Fudong; He, Hong; Zhang, Changbin

    2008-05-01

    An iron titanate catalyst with a crystallite phase, prepared by a co-precipitation method, showed excellent activity, stability, selectivity and SO(2)/H(2)O durability in the selective catalytic reduction of NO with NH(3) in the medium temperature range.

  11. Design and Synthesis of an MOF Thermometer with High Sensitivity in the Physiological Temperature Range.

    PubMed

    Zhao, Dian; Rao, Xingtang; Yu, Jiancan; Cui, Yuanjing; Yang, Yu; Qian, Guodong

    2015-12-01

    An important result of research on mixed-lanthanide metal-organic frameworks (M'LnMOFs) is the realization of highly sensitive ratiometric luminescent thermometers. Here, we report the design and synthesis of the new M'LnMOF Tb0.80Eu0.20BPDA with high relative sensitivity in the physiological temperature regime (298-318 K). The emission intensity and luminescence lifetime were investigated and compared to those of existing materials. It was found that the temperature-dependent luminescence properties of Tb0.80Eu0.20BPDA are strongly associated with the distribution of the energy levels of the ligand. Such a property can be useful in the design of highly sensitive M'LnMOF thermometers.

  12. Larval growth rates of the blowfly, Calliphora vicina, over a range of temperatures.

    PubMed

    Donovan, S E; Hall, M J R; Turner, B D; Moncrieff, C B

    2006-03-01

    Blowfly larvae (Diptera: Calliphoridae) fulfil an important ecological function in the decomposition of animal remains. They are also used extensively in forensic entomology, predominantly to establish a minimum time since death, or a minimum post-mortem interval, using the larval length as a 'biological clock'. This study examined the larval growth rate of a forensically important fly species, Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) at temperatures of between 4 degrees C and 30 degrees C, under controlled laboratory conditions. The laboratory flies had been trapped initially in London, U.K. The minimum developmental temperature was estimated to be 1 degrees C and 4700 accumulated degree hours (ADH) were required for development from egg hatch to the point of pupariation. Lines fitted to the laboratory larval growth data were found to adequately explain the growth of larvae in the field. The nature of variation in growth rates from geographically isolated populations is discussed.

  13. Optical properties of bismuth-doped silica fibres in the temperature range 300 - 1500 K

    SciTech Connect

    Dvoretskii, D A; Bufetov, Igor' A; Vel'miskin, V V; Zlenko, Alexander S; Khopin, V F; Semjonov, S L; Guryanov, Aleksei N; Denisov, L K; Dianov, Evgenii M

    2012-09-30

    The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi{sup 3+} profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect. (optical fibres, lasers and amplifiers. properties and applications)

  14. Measurement of ion motional heating rates over a range of trap frequencies and temperatures

    NASA Astrophysics Data System (ADS)

    Bruzewicz, C. D.; Sage, J. M.; Chiaverini, J.

    2015-04-01

    We present measurements of the motional heating rate of a trapped ion at different trap frequencies and temperatures between ˜0.6 and 1.5 MHz and ˜4 and 295 K. Additionally, we examine the possible effect of adsorbed surface contaminants with boiling points below ˜105 ∘C by measuring the ion heating rate before and after locally baking our ion trap chip under ultrahigh vacuum conditions. We compare the heating rates presented here to those calculated from available electric-field noise models. We can tightly constrain a subset of these models based on their expected frequency and temperature scaling interdependence. Discrepancies between the measured results and predicted values point to the need for refinement of theoretical noise models in order to more fully understand the mechanisms behind motional trapped-ion heating.

  15. Single-ion polymer electrolyte membranes enable lithium-ion batteries with a broad operating temperature range.

    PubMed

    Cai, Weiwei; Zhang, Yunfeng; Li, Jing; Sun, Yubao; Cheng, Hansong

    2014-04-01

    Conductive processes involving lithium ions are analyzed in detail from a mechanistic perspective, and demonstrate that single ion polymeric electrolyte (SIPE) membranes can be used in lithium-ion batteries with a wide operating temperature range (25-80 °C) through systematic optimization of electrodes and electrode/electrolyte interfaces, in sharp contrast to other batteries equipped with SIPE membranes that display appreciable operability only at elevated temperatures (>60 °C). The performance is comparable to that of batteries using liquid electrolyte of inorganic salt, and the batteries exhibit excellent cycle life and rate performance. This significant widening of battery operation temperatures coupled with the inherent flexibility and robustness of the SIPE membranes makes it possible to develop thin and flexible Li-ion batteries for a broad range of applications.

  16. Photochemistry of benzophenone in aliphatic amines studied by laser photolysis in the temperature range 300-77 K

    SciTech Connect

    Hoshino, M.; Shizuka, H.

    1987-01-29

    Laser photolysis studies of benzophenone in both sec-butylamine and triethylamines were carried out in the temperature range 300-77 K. For the sec-butylamine solution of benzophenone, the transients observed after laser pulsing are found to be the ketyl and anion radicals of benzophenone. The ratio of the yield for the formation of ketyl radical to that of the anion radical is markedly dependent on temperature: the ketyl radical is the major product at high temperatures while the anion radical becomes predominant at low temperatures. On the other hand, the triethylamine solution of benzophenone gives solely the ketyl radical as a photoproduct in the temperature range studied. The photochemical reaction of benzophenone in both sec-butylamine and triethylamine is markedly suppressed on going from high to low temperatures. These results are discussed in detail on the basis of the photochemical reaction mechanism involving the formation of the triplet charge-transfer complex (i.e., triplet exciplex) between triplet benzophenone and an amine molecule. The solvent effects on the photoreaction are also discussed.

  17. A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer

    NASA Astrophysics Data System (ADS)

    Marciniak, L.; Prorok, K.; Francés-Soriano, L.; Pérez-Prieto, J.; Bednarkiewicz, A.

    2016-02-01

    The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale.The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle

  18. KINETIC MONTE CARLO STUDIES OF H{sub 2} FORMATION ON GRAIN SURFACES OVER A WIDE TEMPERATURE RANGE

    SciTech Connect

    Iqbal, Wasim; Acharyya, Kinsuk; Herbst, Eric

    2012-05-20

    We have used the continuous-time random-walk Monte Carlo technique to study the formation of H{sub 2} from two hydrogen atoms on the surface of interstellar dust grains with both physisorption and chemisorption sites on olivine and carbonaceous material. In our standard approach, atoms must first enter the physisorption site before chemisorption can occur. We have considered hydrogen atom mobility due to both thermal hopping and quantum mechanical tunneling. The temperature range between 5 K and 825 K has been explored for different incoming H fluxes representative of interstellar environments with atomic hydrogen number density ranging between 0.1 cm{sup -3} and 100 cm{sup -3} and dust grain sizes ranging from 100 sites to 10{sup 6} sites, the latter corresponding roughly to olivine grains of radius 0.2 {mu}m. In addition, we have also considered rough surfaces with multiple binding sites. Tunneling is found to dominate the surface chemistry at low temperature, but as the temperature increases, the scenario changes. The inclusion of chemisorption sites can provide a meaningful efficiency for H{sub 2} production up to temperatures as high as 700 K depending upon the depth of the chemisorption well. We found that over virtually the entire temperature range studied, the use of rate equations overestimates the H{sub 2} formation rate to some extent. This overestimate is large at high temperatures, due to very low surface residence times. We have also considered models in which chemisorption sites are entered directly and diffusion proceeds only to other chemisorption sites.

  19. Divinyl-end-functionalized polyethylenes: ready access to a range of telechelic polyethylenes through thiol-ene reactions.

    PubMed

    Norsic, Sebastien; Thomas, Coralie; D'Agosto, Franck; Boisson, Christophe

    2015-04-01

    Telechelic α,ω-iodo-vinyl-polyethylenes (Vin-PE-I) were obtained by catalytic ethylene polymerization in the presence of [(C5 Me5 )2 NdCl2 Li(OEt2 )2 ] in combination with a functionalized chain-transfer agent, namely, di(10-undecenyl)magnesium, followed by treatment of the resulting di(vinylpolyethylenyl)magnesium compounds ((vinyl-PE)2 Mg) with I2 . The iodo-functionalized vinylpolyethylenes (Vin-PE-I) were transformed into unique divinyl-functionalized polyethylenes (Vin-PE-Vin) by simple treatment with tBuOK in toluene at 95 °C. Thiol-ene reactions were then successfully performed on Vin-PE-Vin with functionalized thiols in the presence of AIBN. A range of homobifunctional telechelic polyethylenes were obtained on which a hydroxy, diol, carboxylic acid, amine, ammonium chloride, trimethoxysilyl, chloro, or fluoroalkyl group was installed quantitatively at each chain end. PMID:25688747

  20. Analysis of electrical conduction mechanism in the high temperature range of the nanostructured photoabsorber Cu2SnS3

    NASA Astrophysics Data System (ADS)

    Lahlali, S.; Essaleh, L.; Belaqziz, M.; Chehouani, H.; Djessas, K.; Viallet, B.

    2016-11-01

    The dynamic electrical conduction in the bulk ternary semiconductor compound Cu2SnS3 is studied for the first time in the high temperature range from 300 °C to 440 °C in the frequency range 1 kHz-1 MHz. New activation energy for conduction mechanism is obtained and its frequency dependence is analyzed. The Cole-Cole representation is almost half circular indicating a single contribution to total electrical conduction through the material. The activation energy for the mean relaxation process, obtained separately from the analysis of imaginary part Z″ of complex impedance Z* and from the equivalent electric circuit, is estimated to be (942 ± 74) meV . The correlated barrier hopping model is considered to analyze the experimental data. The results are compared with those obtained previously in low temperature range.

  1. High temperature range recuperator. Phase II. Prototype demonstration and material and analytical studies. Final report

    SciTech Connect

    1980-04-01

    A summary of the work performed to fully evaluate the commercial potential of a unique ceramic recuperator for use in recovering waste heat from high temperature furnace exhaust gases is presented. The recuperator concept being developed consists of a vertical cylindrical heat exchange column formed from modular sections. Within the column, the gasketed modules form two helical flow passages - one for high temperature exhaust gases and one for pre-heating combustion air. The column is operated in a counterflow mode, with the exhaust gas entering at the bottom and the combustion air entering at the top of the column. Activities included design and procurement of prototype recuperator modules, construction and testing of two prototype recuperator assemblies, exposure and mechanical properties testing of candidate materials, structural analysis of the modules, and assessment of the economic viability of the concept. The results of the project indicated that the proposed recuperator concept was feasible from a technical standpoint. Economic analysis based upon recuperator performance characteristics and module manufacturing costs defined during the program indicated that 3 to 10 years (depending upon pre-heat temperature) would be required to recover the capital cost of the system in combustion air preheat applications. At this stage in the development of the recuperator, many factors in the analysis had to be assumed. Significant changes in some of the assumptions could dramatically affect the economics. For example, utilizing $2.85 per mcf for the natural gas price (as opposed to $2.00 per mcf) could reduce the payback period by more than half in certain cases. In addition, future commercial application will depend upon ceramic component manufacturing technique advances and cost reduction.

  2. Data Transfer for Multiple Sensor Networks Over a Broad Temperature Range

    NASA Technical Reports Server (NTRS)

    Krasowski, Michael

    2013-01-01

    At extreme temperatures, cryogenic and over 300 C, few electronic components are available to support intelligent data transfer over a common, linear combining medium. This innovation allows many sensors to operate on the same wire bus (or on the same airwaves or optical channel: any linearly combining medium), transmitting simultaneously, but individually recoverable at a node in a cooler part of the test area. This innovation has been demonstrated using room-temperature silicon microcircuits as proxy. The microcircuits have analog functionality comparable to componentry designed using silicon carbide. Given a common, linearly combining medium, multiple sending units may transmit information simultaneously. A listening node, using various techniques, can pick out the signal from a single sender, if it has unique qualities, e.g. a voice. The problem being solved is commonly referred to as the cocktail party problem. The human brain uses the cocktail party effect when it is able to recognize and follow a single conversation in a party full of talkers and other noise sources. High-temperature sensors have been used in silicon carbide electronic oscillator circuits. The frequency of the oscillator changes as a function of the changes in the sensed parameter, such as pressure. This change is analogous to changes in the pitch of a person s voice. The output of this oscillator and many others may be superimposed onto a single medium. This medium may be the power lines supplying current to the sensors, a third wire dedicated to data transmission, the airwaves through radio transmission, an optical medium, etc. However, with nothing to distinguish the identities of each source that is, the source separation this system is useless. Using digital electronic functions, unique codes or patterns are created and used to modulate the output of the sensor.

  3. Reply to "Comment on 'Temperature inversion in long-range interacting systems' ".

    PubMed

    Teles, Tarcísio N; Gupta, Shamik; Di Cintio, Pierfrancesco; Casetti, Lapo

    2016-06-01

    We present evidence that the mechanism proposed in Teles et al. [Phys. Rev. E 92, 020101 (2015)PRESCM1539-375510.1103/PhysRevE.92.020101], referred to as the TGDC mechanism, does apply to a model with repulsive mean-field interactions where it produces temperature inversion in a state whose inhomogeneity is due to an external field. Such evidence contradicts the core statement of the Comment. We also discuss a related issue, concerning the possible application of the TGDC mechanism to the solar corona.

  4. Reply to "Comment on 'Temperature inversion in long-range interacting systems' ".

    PubMed

    Teles, Tarcísio N; Gupta, Shamik; Di Cintio, Pierfrancesco; Casetti, Lapo

    2016-06-01

    We present evidence that the mechanism proposed in Teles et al. [Phys. Rev. E 92, 020101 (2015)PRESCM1539-375510.1103/PhysRevE.92.020101], referred to as the TGDC mechanism, does apply to a model with repulsive mean-field interactions where it produces temperature inversion in a state whose inhomogeneity is due to an external field. Such evidence contradicts the core statement of the Comment. We also discuss a related issue, concerning the possible application of the TGDC mechanism to the solar corona. PMID:27415396

  5. An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

    PubMed

    Barwart, O; Rollinger, J M; Burger, A

    1999-10-01

    Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

  6. KEX2 mutations suppress RNA polymerase II mutants and alter the temperature range of yeast cell growth.

    PubMed Central

    Martin, C; Young, R A

    1989-01-01

    Suppressors of a temperature-sensitive RNA polymerase II mutation were isolated to identify proteins that interact with RNA polymerase II in yeast cells. Ten independently isolated extragenic mutations that suppressed the temperature-sensitive mutation rpb1-1 and produced a cold-sensitive phenotype were all found to be alleles of a single gene, SRB1. An SRB1 partial deletion mutant was further investigated and found to exhibit several pleiotropic phenotypes. These included suppression of numerous temperature-sensitive RNA polymerase II mutations, alteration of the temperature growth range of cells containing wild-type RNA polymerase, and sterility of cells of alpha mating type. The ability of SRB1 mutations to suppress the temperature-sensitive phenotype of RNA polymerase II mutants did not extend to other temperature-sensitive mutants investigated. Isolation of the SRB1 gene revealed that SRB1 is KEX2. These results indicate that the KEX2 protease, whose only known substrates are hormone precursors, can have an important influence on RNA polymerase II and the temperature-dependent growth properties of yeast cells. Images PMID:2668732

  7. Characterization of polymers in the glass transition range: Time-temperature and time-aging time superposition in polycarbonate

    SciTech Connect

    Pesce, J.J.; Niemiec, J.M.; Chiang, M.Y.

    1995-12-31

    Here we present time-temperature and time-aging time superposition data for a commercial grade polycarbonate. The data reduction is performed for dynamic-mechanical data obtained in torsion over a range of temperatures from 103.6 to 144.5{degrees}C and aging times to 16 h. For time-temperature superposition the results show the deviation of the sub-T{sub g} response from the WTF equation. Two response regimes are observed: at temperatures far below T{sub g} the log(a{sub T}) is linear in T, followed by a transition towards the WLF behavior as T{sub g} is approached. The temperature at which the behavior changes from a linear dependence of log(aT) on T to the transition-type behavior is found to depend on the aging time. This temperature decreases as aging time increases. The time-aging time response is found to behave in a normal way. At temperatures far below T{sub g} the log(a{sub te}) vs log(t{sub e}) is constant and has a slope somewhat less than unity. However, nearer to T{sub g} the slope decreases and there is a second regime in which the aging virtually ceases. In this polycarbonate, above 136.9{degrees}C, no aging is observed.

  8. Web-based interactive access, analysis and comparison of remotely sensed and in situ measured temperature data

    NASA Astrophysics Data System (ADS)

    Eberle, Jonas; Urban, Marcel; Hüttich, Christian; Schmullius, Christiane

    2014-05-01

    Numerous datasets providing temperature information from meteorological stations or remote sensing satellites are available. However, the challenging issue is to search in the archives and process the time series information for further analysis. These steps can be automated for each individual product, if the pre-conditions are complied, e.g. data access through web services (HTTP, FTP) or legal rights to redistribute the datasets. Therefore a python-based package was developed to provide data access and data processing tools for MODIS Land Surface Temperature (LST) data, which is provided by NASA Land Processed Distributed Active Archive Center (LPDAAC), as well as the Global Surface Summary of the Day (GSOD) and the Global Historical Climatology Network (GHCN) daily datasets provided by NOAA National Climatic Data Center (NCDC). The package to access and process the information is available as web services used by an interactive web portal for simple data access and analysis. Tools for time series analysis were linked to the system, e.g. time series plotting, decomposition, aggregation (monthly, seasonal, etc.), trend analyses, and breakpoint detection. Especially for temperature data a plot was integrated for the comparison of two temperature datasets based on the work by Urban et al. (2013). As a first result, a kernel density plot compares daily MODIS LST from satellites Aqua and Terra with daily means from GSOD and GHCN datasets. Without any data download and data processing, the users can analyze different time series datasets in an easy-to-use web portal. As a first use case, we built up this complimentary system with remotely sensed MODIS data and in situ measurements from meteorological stations for Siberia within the Siberian Earth System Science Cluster (www.sibessc.uni-jena.de). References: Urban, Marcel; Eberle, Jonas; Hüttich, Christian; Schmullius, Christiane; Herold, Martin. 2013. "Comparison of Satellite-Derived Land Surface Temperature and Air

  9. Temperature-modulated annealing of c-plane sapphire for long-range-ordered atomic steps

    NASA Astrophysics Data System (ADS)

    Yatsui, Takashi; Kuribara, Kazunori; Sekitani, Tsuyoshi; Someya, Takao; Yoshimoto, Mamoru

    2016-03-01

    High-quality single-crystalline sapphire is used to prepare various semiconductors because of its thermal stability. Here, we applied the tempering technique, which is well known in the production of chocolate, to prepare a sapphire substrate. Surprisingly, we successfully realised millimetre-range ordering of the atomic step of the sapphire substrate. We also obtained a sapphire atomic step with nanometre-scale uniformity in the terrace width and atomic-step height. Such sapphire substrates will find applications in the preparation of various semiconductors and devices.

  10. Physical activity profile of 2014 FIFA World Cup players, with regard to different ranges of air temperature and relative humidity

    NASA Astrophysics Data System (ADS)

    Chmura, Paweł; Konefał, Marek; Andrzejewski, Marcin; Kosowski, Jakub; Rokita, Andrzej; Chmura, Jan

    2016-09-01

    The present study attempts to assess changes in soccer players' physical activity profiles under the simultaneous influence of the different combinations of ambient temperature and relative humidity characterising matches of the 2014 FIFA World Cup hosted by Brazil. The study material consisted of observations of 340 players representing 32 national teams taking part in the tournament. The measured indices included total distances covered; distances covered with low, moderate, or high intensity; numbers of sprints performed, and peak running speeds achieved. The analysis was carried out using FIFA official match data from the Castrol Performance Index system. Ultimately, consideration was given to a combination of three air temperature ranges, i.e. below 22 °C, 22-28 °C, and above 28 °C; and two relative humidity ranges below 60 % and above 60 %. The greatest average distance recorded (10.54 ± 0.91 km) covered by players at an air temperature below 22 °C and a relative humidity below 60 %, while the shortest (9.83 ± 1.08 km) characterised the same air temperature range, but conditions of relative humidity above 60 % (p ≤ 0.001). Two-way ANOVA revealed significant differences (p ≤ 0.001) in numbers of sprints performed by players, depending on whether the air temperature range was below 22 °C (40.48 ± 11.17) or above 28 °C (30.72 ± 9.40), but only where the relative humidity was at the same time below 60 %. Results presented indicate that the conditions most comfortable for physical activity on the part of players occur at 22 °C, and with relative humidity under 60 %.

  11. Communication: Accurate hydration free energies at a wide range of temperatures from 3D-RISM.

    PubMed

    Misin, Maksim; Fedorov, Maxim V; Palmer, David S

    2015-03-01

    We present a new model for computing hydration free energies by 3D reference interaction site model (3D-RISM) that uses an appropriate initial state of the system (as suggested by Sergiievskyi et al.). The new adjustment to 3D-RISM theory significantly improves hydration free energy predictions for various classes of organic molecules at both ambient and non-ambient temperatures. An extensive benchmarking against experimental data shows that the accuracy of the model is comparable to (much more computationally expensive) molecular dynamics simulations. The calculations can be readily performed with a standard 3D-RISM algorithm. In our work, we used an open source package AmberTools; a script to automate the whole procedure is available on the web (https://github.com/MTS-Strathclyde/ISc). PMID:25747054

  12. One year in the life of Bufo punctatus: annual patterns of body temperature in a free-ranging desert anuran.

    PubMed

    Rausch, Candice M; Starkweather, Peter L; van Breukelen, Frank

    2008-06-01

    The Mojave Desert is characterized by hot dry summers and cold winters. The red-spotted toad (Bufo (Anaxyrus) punctatus) is the predominant anuran species; yet little is known of their thermal histories and strategies to avoid temperature extremes. We measured body temperature (T(b)) in free-ranging adult toads across all four seasons of a year using implanted data loggers. There is marked individual variation in the temperatures experienced by these toads. As expected, toads generally escape extreme seasonal and diel temperature fluctuations. However, our data demonstrate a much wider estimated T(b) range than was previously assumed. Though often for short periods, red-spotted toads do experience T(b) as low as 3.1 degrees C and as high as 39.1 degrees C. All animals showed periods of prolonged thermal stability in cooler months and wider diel oscillations in warmer months. Red-spotted toad thermal history is likely a function of site choice; the exploitation of different refuges results in diverse thermal experiences. These data represent the most complete record of thermal experiences for a desert anuran and reveal greater extremes in body temperature than previously suggested.

  13. One year in the life of Bufo punctatus: annual patterns of body temperature in a free-ranging desert anuran

    NASA Astrophysics Data System (ADS)

    Rausch, Candice M.; Starkweather, Peter L.; van Breukelen, Frank

    2008-06-01

    The Mojave Desert is characterized by hot dry summers and cold winters. The red-spotted toad ( Bufo ( Anaxyrus) punctatus) is the predominant anuran species; yet little is known of their thermal histories and strategies to avoid temperature extremes. We measured body temperature ( T b) in free-ranging adult toads across all four seasons of a year using implanted data loggers. There is marked individual variation in the temperatures experienced by these toads. As expected, toads generally escape extreme seasonal and diel temperature fluctuations. However, our data demonstrate a much wider estimated T b range than was previously assumed. Though often for short periods, red-spotted toads do experience T b as low as 3.1°C and as high as 39.1°C. All animals showed periods of prolonged thermal stability in cooler months and wider diel oscillations in warmer months. Red-spotted toad thermal history is likely a function of site choice; the exploitation of different refuges results in diverse thermal experiences. These data represent the most complete record of thermal experiences for a desert anuran and reveal greater extremes in body temperature than previously suggested.

  14. Respiratory Response of the Deep-Sea Amphipod Stephonyx biscayensis Indicates Bathymetric Range Limitation by Temperature and Hydrostatic Pressure

    PubMed Central

    Brown, Alastair; Thatje, Sven

    2011-01-01

    Depth zonation of fauna on continental margins is well documented. Whilst increasing hydrostatic pressure with depth has long been considered a factor contributing significantly to this pattern, discussion of the relative significance of decreasing temperature with depth has continued. This study investigates the physiological tolerances of fed and starved specimens of the bathyal lysianassoid amphipod Stephonyx biscayensis at varying temperature to acute pressure exposure by measuring the rate of oxygen consumption. Acclimation to atmospheric pressure is shown to have no significant interaction with temperature and/or pressure effects. Similarly, starvation is shown to have no significant effect on the interaction of temperature and pressure. Subsequently, the effect of pressure on respiration rate is revealed to be dependent on temperature: pressure equivalent to 2000 m depth was tolerated at 1 and 3°C; pressure equivalent to 2500 m depth was tolerated at 5.5°C; at 10°C pressure equivalent to 3000 m depth was tolerated. The variation in tolerance is consistent with the natural distribution range reported for this species. There are clear implications for hypotheses relating to the observed phenomenon of a biodiversity bottleneck between 2000 and 3000 metres, and for the potential for bathymetric range shifts in response to global climate change. PMID:22174838

  15. Kinetic measurements on elementary fossil fuel combustion reactions over wide temperature ranges. Progress report, May 1, 1984--November 30, 1986

    SciTech Connect

    Fontijn, A.; Mahmud, K.; Marshall, P.

    1986-12-01

    The HTP (high-temperature photochemistry technique) has been used to study the reactions of ground state 0 atoms with C{sub 2}H{sub 4}, C{sub 2}H{sub 2}, H{sub 2} and D{sub 2} over the 300 to 1500 K temperature range. The results are described and discussed, as are the plans for study of the 0 + 1,3 butadiene and C{sub 2}H{sub 6} reactions in the remainder of the present grant period.

  16. Optical Properties of Sodium Chloride Solution Within the Spectral Range from 300 to 2500 nm at Room Temperature.

    PubMed

    Li, Xingcan; Liu, Linhua; Zhao, Junming; Tan, Jianyu

    2015-05-01

    The optical properties of sodium chloride (NaCl) solution were experimentally determined by double optical pathlength transmission method in the spectral range from 300 to 2500 nm at the NaCl concentration range from 0 to 360 g/L. The results show that the refractive index of NaCl solution increases with NaCl concentrations and correlates nonlinearly with the concentration of NaCl solution. The absorption index of NaCl solution increases with NaCl concentrations in the visible spectral range of 300-700 nm, but varies little in the near-infrared spectral range of 700-2500 nm at room temperature. For the sake of applications, the fitted formulae of the refractive index and absorption index of NaCl solution as a function of wavelength and NaCl concentration are presented.

  17. Behaviour and modelling of aluminium alloy AA6060 subjected to a wide range of strain rates and temperatures

    NASA Astrophysics Data System (ADS)

    Vilamosa, Vincent; Børvik, Tore; Sture Hopperstad, Odd; Holm Clausen, Arild

    2015-09-01

    The thermo-mechanical behaviour in tension of an as-cast and homogenized AA6060 alloy was investigated at a wide range of strains (the entire deformation process up to fracture), strain rates (0.01-750 s-1) and temperatures (20-350 ∘C). The tests at strain rates up to 1 s-1 were performed in a universal testing machine, while a split-Hopkinson tension bar (SHTB) system was used for strain rates from 350 to 750 s-1. The samples were heated with an induction-based heating system. A typical feature of aluminium alloys at high temperatures is that necking occurs at a rather early stage of the deformation process. In order to determine the true stress-strain curve also after the onset of necking, all tests were instrumented with a digital camera. The experimental tests reveal that the AA6060 material has negligible strain-rate sensitivity (SRS) for temperatures lower than 200 ∘C, while both yielding and work hardening exhibit a strong positive SRS at higher temperatures. The coupled strain-rate and temperature sensitivity is challenging to capture with most existing constitutive models. The paper presents an outline of a new semi-physical model that expresses the flow stress in terms of plastic strain, plastic strain rate and temperature. The parameters of the model were determined from the tests, and the stress-strain curves from the tests were compared with the predictions of the model. Good agreement was obtained over the entire strain rate and temperature range.

  18. Operating Range for High Temperature Borosilicate Waste Glasses: (Simulated Hanford Enveloped)

    SciTech Connect

    Mohammad, J.; Ramsey, W. G.; Toghiani, R. K.

    2003-02-24

    The following results are a part of an independent thesis study conducted at Diagnostic Instrumentation and Analysis Laboratory-Mississippi State University. A series of small-scale borosilicate glass melts from high-level waste simulant were produced with waste loadings ranging from 20% to 55% (by mass). Crushed glass was allowed to react in an aqueous environment under static conditions for 7 days. The data obtained from the chemical analysis of the leachate solutions were used to test the durability of the resulting glasses. Studies were performed to determine the qualitative effects of increasing the B2O3 content on the overall waste glass leaching behavior. Structural changes in a glass arising due to B2O3 were detected indirectly by its chemical durability, which is a strong function of composition and structure. Modeling was performed to predict glass durability quantitatively in an aqueous environment as a direct function of oxide composition.

  19. Importance of maintaining the newly born temperature in the normal range from delivery to admission.

    PubMed

    Chitty, Helen; Wyllie, Jonathan

    2013-12-01

    Over the last 50 years an increasing amount of evidence on neonatal resuscitation and stabilisation practices has led to written recommendations on all aspects of newborn care in the first few minutes of life. Much evidence for thermoregulatory management of both term and preterm infants has existed for decades and more recently research has identified new techniques to maintain normothermia in newly born infants. The use of increased environmental temperatures, skin-to-skin care, radiant warmers, plastic coverings and hats, exothermic mattresses and heated humidified gases have or are undergoing evaluation. However, despite the apparent acceptance of these techniques, a substantial number of infants continue to become hypothermic soon after delivery, leading to an increased risk of comorbidities and of death. Gaps in our knowledge remain and further research opportunities are available. However, we must also ensure that established thermoregulatory methods for which the evidence already exists are given as much emphasis as other aspects of newborn care and are implemented meticulously in all healthcare settings. PMID:24055301

  20. Natural variability of atmospheric temperatures and geomagnetic intensity over a wide range of time scales

    PubMed Central

    Pelletier, Jon D.

    2002-01-01

    The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208

  1. Atmospheric aerosol impacts on sea surface temperatures and medium range forecast.

    NASA Astrophysics Data System (ADS)

    Oyola, M. I.; Joseph, E.; Lu, C. H.; Nalli, N. R.

    2014-12-01

    This work proposes a series of experiments to analyze the impact of dust aerosols on numerical weather prediction (NWP) and the global data assimilation system. We strive to accomplish this by the application of the NOAA Environmental Modeling System/Global Forecasting System (NEMS/GFS) aerosol component (NGAC), which corresponds to the first global interactive atmosphere-aerosol forecast system ever implemented at NOAA's National Center for Environmental Prediction (NCEP) and which has been operational since September 2012. Specifically, our approach will include the implementation of an improved satellite sea surface temperature (SST) retrieval methodology, that allows for better representation of the atmospheric state under dust-laden conditions. Specifically, the new algorithm will be included within the NGAC aerosol product to improve the accuracy of the SST analysis and examine the impact on NWP, particularly in tropical cyclone genesis regions in the eastern Atlantic. The results of these corrections are validated against observed measurements from the eastern Atlantic Ocean, which is dominated by Saharan dust throughout most of the year and that is also a genesis region for Atlantic tropical cyclones. These observations are obtained from the NOAA Aerosols and Ocean Science Expeditions (AEROSE) and PIRATA Northeast Extension (PNE) buoys network. We believe that the improved physical SST methodology has the potential to allow for improved representation of the geophysical state under dust-laden conditions

  2. Natural variability of atmospheric temperatures and geomagnetic intensity over a wide range of time scales.

    PubMed

    Pelletier, Jon D

    2002-02-19

    The majority of numerical models in climatology and geomagnetism rely on deterministic finite-difference techniques and attempt to include as many empirical constraints on the many processes and boundary conditions applicable to their very complex systems. Despite their sophistication, many of these models are unable to reproduce basic aspects of climatic or geomagnetic dynamics. We show that a simple stochastic model, which treats the flux of heat energy in the atmosphere by convective instabilities with random advection and diffusive mixing, does a remarkable job at matching the observed power spectrum of historical and proxy records for atmospheric temperatures from time scales of one day to one million years (Myr). With this approach distinct changes in the power-spectral form can be associated with characteristic time scales of ocean mixing and radiative damping. Similarly, a simple model of the diffusion of magnetic intensity in Earth's core coupled with amplification and destruction of the local intensity can reproduce the observed 1/f noise behavior of Earth's geomagnetic intensity from time scales of 1 (Myr) to 100 yr. In addition, the statistics of the fluctuations in the polarity reversal rate from time scales of 1 Myr to 100 Myr are consistent with the hypothesis that reversals are the result of variations in 1/f noise geomagnetic intensity above a certain threshold, suggesting that reversals may be associated with internal fluctuations rather than changes in mantle thermal or magnetic boundary conditions. PMID:11875208

  3. Long-range order in a high-density electron-hole system at room temperature during superradiant phase transition

    NASA Astrophysics Data System (ADS)

    Vasil'ev, Peter P.; Olle, Vojtech; Penty, Richard V.; White, Ian H.

    2013-11-01

    We have experimentally investigated the formation of off-diagonal long-range order and non-equilibrium BEC-like condensation in GaAs/AlGaAs heterostructures during superradiant (SR) emission at room temperature. The conclusive evidence of the establishment of phase coherence over a macroscopic range during the superradiant quantum phase transition is reported. The first-order spatial correlation function of the e-h system is determined by evaluating interference patterns of SR emission using Young's double slit.

  4. Structural development of high-temperature mylonites in the Archean Wyoming province, northwestern Madison Range, Montana

    USGS Publications Warehouse

    Kellogg, Karl S.; Mogk, David W.

    2009-01-01

    The Crooked Creek mylonite, in the northwestern Madison Range, southwestern Montana, is defined by several curved lenses of high non-coaxial strain exposed over a 7-km-wide, northeast-trending strip. The country rocks, part of the Archean Wyoming province, are dominantly trondhjemitic to granitic orthogneiss with subordinate amphibolite, quartzite, aluminous gneiss, and sills of metabasite (mafic granulite). Data presented here support an interpretation that the mylonite formed during a period of rapid, heterogeneous strain at near-peak metamorphic conditions during an early deformational event (D1) caused by northwest–southeast-directed transpression. The mylonite has a well-developed L-S tectonite fabric and a fine-grained, recrystallized (granoblastic) texture. The strong linear fabric, interpreted as the stretching direction, is defined by elongate compositional “fish,” fold axes, aligned elongate minerals, and mullion axes. The margins of the mylonitic zones are concordant with and grade into regions of unmylonitized gneiss. A second deformational event (D2) has folded the mylonite surface to produce meter- to kilometer-scale, tight-to-isoclinal, gently plunging folds in both the mylonite and country rock, and represents a northwest–southeast shortening event. Planar or linear fabrics associated with D2 are remarkably absent. A third regional deformational event (D3) produced open, kilometer-scale folds generally with gently north-plunging fold axes. Thermobarometric measurements presented here indicate that metamorphic conditions during D1 were the same in both the mylonite and the country gneiss, reaching upper amphibolite- to lower granulite-facies conditions: 700 ± 50° C and 8.5 ± 0.5 kb. Previous geochronological studies of mylonitic and cross-cutting rocks in the Jerome Rock Lake area, east of the Crooked Creek mylonite, bracket the timing of this high-grade metamorphism and mylonitization between 2.78 and 2.56 Ga, nearly a billion years

  5. Study of temperature dependence of thermal conductivity in cross-linked epoxies using molecular dynamics simulations with long range interactions

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Sundararaghavan, V.; Browning, A. R.

    2014-03-01

    In this work, we demonstrate the use of the Green-Kubo integral of the heat flux autocorrelation function, incorporating long-range corrections to model the thermal conductivity versus temperature relationship of cross-linked polymers. The simulations were performed on a cross-linked epoxy made from DGEBA and a curing agent (diamino diphenyl sulfone) using a consistent valence force field (CVFF). A dendrimeric approach was utilized for building equilibrated cross-linked structures that allowed replication of the experimental dilatometric curve for the epoxy system. We demonstrate that the inclusion of a long-range correction within the Ewald/PPPM approach brings the results close to experimentally measured conductivity within an error of 10% while providing a good prediction of the relationship of thermal conductivity versus temperature. This method shows significant promise towards the computation of thermal conductivity from simulations even before synthesis of the polymer for purposes of materials by design.

  6. Performance of a 100V Half-Bridge MOSFET Driver, Type MIC4103, Over a Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Hammoud, Ahmad

    2011-01-01

    The operation of a high frequency, high voltage MOSFET (metal-oxide semiconductor field-effect transistors) driver was investigated over a wide temperature regime that extended beyond its specified range. The Micrel MIC4103 is a 100V, non-inverting, dual driver that is designed to independently drive both high-side and low-side N-channel MOSFETs. It features fast propagation delay times and can drive 1000 pF load with 10ns rise times and 6 ns fall times [1]. The device consumes very little power, has supply under-voltage protection, and is rated for a -40 C to +125 C junction temperature range. The floating high-side driver of the chip can sustain boost voltages up to 100 V. Table I shows some of the device manufacturer s specification.

  7. Rate constant for the reaction of hydroxyl radical with formaldehyde over the temperature range 228-362 K

    NASA Technical Reports Server (NTRS)

    Stief, L. J.; Nava, D. F.; Payne, W. A.; Michael, J. V.

    1980-01-01

    Absolute rate constants for the reaction OH ? H2CO measured over the temperature range 228-362 K using the flash photolysis-resonance fluorescence technique are given. The results are independent of variations in H2CO concentration, total pressure Ar concentration, and flash intensity (i.e., initial OH concentration). The rate constant is found to be invariant with temperature in this range, the best representation being k sub 1 = (1.05 ? or - 0.11) x 10 to the 11th power cu cm molecule(-1) s(-1) where the error is two standard deviations. This result is compared with previous absolute and relative determinations of k sub 1. The reaction is also discussed from a theoretical point of view.

  8. Altitudinal ranging of black-crested gibbons at Mt. Wuliang, Yunnan: effects of food distribution, temperature and human disturbance.

    PubMed

    Fan, Peng-Fei; Jiang, Xue-Long

    2010-01-01

    We studied the altitudinal ranging of one habituated group of black-crested gibbons (Nomascus concolor) at Dazhaizi, Mt. Wuliang, Yunnan, China, between March 2005 and April 2006. The group ranged from 1,900 to 2,680 m above sea level. Food distribution was the driving force behind the altitudinal ranging patterns of the study group. They spent 83.2% of their time ranging between 2,100 and 2,400 m, where 75.8% of important food patches occurred. They avoided using the area above 2,500 m despite a lack of human disturbance there, apparently because there were few food resources. Temperature had a limited effect on seasonal altitudinal ranging but probably explained the diel altitudinal ranging of the group, which tended to use the lower zone in the cold morning and the higher zone in the warm afternoon. Grazing goats, the main disturbance, were limited to below 2,100 m, which was defined as the high-disturbance area (HDA). Gibbons spent less time in the HDA and, when ranging there, spent more time feeding and travelling and less time resting and singing. Human activities directly influenced gibbon behaviour, might cause forest degradation and create dispersal barriers between populations.

  9. Mangrove expansion and contraction at a poleward range limit: Climate extremes and land-ocean temperature gradients

    USGS Publications Warehouse

    Osland, Michael J.; Day, Richard H.; Hall, Courtney T.; Brumfield, Marisa D; Dugas, Jason; Jones, William R.

    2016-01-01

    Within the context of climate change, there is a pressing need to better understand the ecological implications of changes in the frequency and intensity of climate extremes. Along subtropical coasts, less frequent and warmer freeze events are expected to permit freeze-sensitive mangrove forests to expand poleward and displace freeze-tolerant salt marshes. Here, our aim was to better understand the drivers of poleward mangrove migration by quantifying spatiotemporal patterns in mangrove range expansion and contraction across land-ocean temperature gradients. Our work was conducted in a freeze-sensitive mangrove-marsh transition zone that spans a land-ocean temperature gradient in one of the world's most wetland-rich regions (Mississippi River Deltaic Plain; Louisiana, USA). We used historical air temperature data (1893-2014), alternative future climate scenarios, and coastal wetland coverage data (1978-2011) to investigate spatiotemporal fluctuations and climate-wetland linkages. Our analyses indicate that changes in mangrove coverage have been controlled primarily by extreme freeze events (i.e., air temperatures below a threshold zone of -6.3 to -7.6 °C). We expect that in the past 121 years, mangrove range expansion and contraction has occurred across land-ocean temperature gradients. Mangrove resistance, resilience, and dominance were all highest in areas closer to the ocean where temperature extremes were buffered by large expanses of water and saturated soil. Under climate change, these areas will likely serve as local hotspots for mangrove dispersal, growth, range expansion, and displacement of salt marsh. Collectively, our results show that the frequency and intensity of freeze events across land-ocean temperature gradients greatly influences spatiotemporal patterns of range expansion and contraction of freeze-sensitive mangroves. We expect that, along subtropical coasts, similar processes govern the distribution and abundance of other freeze

  10. Temperature dependence of oxygen- and clumped isotope fractionation in carbonates: A study of travertines and tufas in the 6-95 °C temperature range

    NASA Astrophysics Data System (ADS)

    Kele, Sándor; Breitenbach, Sebastian F. M.; Capezzuoli, Enrico; Meckler, A. Nele; Ziegler, Martin; Millan, Isabel M.; Kluge, Tobias; Deák, József; Hanselmann, Kurt; John, Cédric M.; Yan, Hao; Liu, Zaihua; Bernasconi, Stefano M.

    2015-11-01

    Conventional carbonate-water oxygen isotope thermometry and the more recently developed clumped isotope thermometer have been widely used for the reconstruction of paleotemperatures from a variety of carbonate materials. In spite of a large number of studies, however, there are still large uncertainties in both δ18O- and Δ47-based temperature calibrations. For this reason there is a need to better understand the controls on isotope fractionation especially on natural carbonates. In this study we analyzed oxygen, carbon and clumped isotopes of a unique set of modern calcitic and aragonitic travertines, tufa and cave deposits from natural springs and wells. Together these samples cover a temperature range from 6 to 95 °C. Travertine samples were collected close to the vents of the springs and from pools, and tufa samples were collected from karstic creeks and a cave. The majority of our vent and pool travertines and tufa samples show a carbonate-water oxygen isotope fractionation comparable to the one of Tremaine et al. (2011) with some samples showing higher fractionations. No significant difference between the calcite-water and aragonite-water oxygen isotope fractionation could be observed. The Δ47 data from the travertines show a strong relationship with temperature and define the regression Δ47 = (0.044 ± 0.005 × 106)/T2 + (0.205 ± 0.047). The pH of the parent solution, mineralogy and precipitation rate do not appear to significantly affect the Δ47-signature of carbonates, compared to the temperature effect and the analytical error. The tufa samples and three biogenic calcites show an excellent fit with the travertine calibration, indicating that this regression can be used for other carbonates as well. This work extends the calibration range of the clumped isotope thermometer to travertine and tufa deposits in the temperature range from 6 °C to 95 °C.

  11. A Centrosymmetric Hexagonal Magnet with Superstable Biskyrmion Magnetic Nanodomains in a Wide Temperature Range of 100-340 K.

    PubMed

    Wang, Wenhong; Zhang, Ying; Xu, Guizhou; Peng, Licong; Ding, Bei; Wang, Yue; Hou, Zhipeng; Zhang, Xiaoming; Li, Xiyang; Liu, Enke; Wang, Shouguo; Cai, Jianwang; Wang, Fangwei; Li, Jianqi; Hu, Fengxia; Wu, Guangheng; Shen, Baogen; Zhang, Xi-Xiang

    2016-08-01

    Superstable biskyrmion magnetic nanodomains are experimentally observed for the first time in a hexagonal MnNiGa, a common and easily produced centrosymmetric material. The biskyrmion states in MnNiGa thin plates, as determined by the combination of in situ Lorentz transmission electron microscopy images, magnetoresistivity, and topological Hall effect measurements, are surprisingly stable over a broad temperature range of 100-340 K. PMID:27192410

  12. Two-phase working fluids for the temperature range 100-350 C. [in heat pipes for solar applications

    NASA Technical Reports Server (NTRS)

    Saaski, E. W.; Tower, L.

    1977-01-01

    The decomposition and corrosion of two-phase heat transfer liquids and metal envelopes have been investigated on the basis of molecular, bond strengths and chemical thermodynamics. Potentially stable heat transfer fluids for the temperature range 100 to 350 C have been identified, and reflux heat pipe tests initiated with 10 fluids and carbon steel and aluminum envelopes to experimentally establish corrosion behavior and noncondensable gas generation rates.

  13. Wide range room temperature electroclinic liquid crystal mixture with large induced tilt and very small layer contraction

    NASA Astrophysics Data System (ADS)

    Debnath, Asim; Sinha, Debashis; Mandal, Pradip Kumar

    2016-03-01

    Optical polarizing microscopy, synchrotron X-ray scattering, and electro-optic studies in the SmA* phase of a formulated wide range room temperature liquid crystal mixture indicate a large electric field induced optical tilt up to 23.5° along with a very small contraction of smectic layers. Applied field primarily lifts the zero-field degeneracy of the azimuthal order of the molecules in smectic layers resulting in small layer contraction.

  14. High-performance bilayer flexible resistive random access memory based on low-temperature thermal atomic layer deposition

    PubMed Central

    2013-01-01

    We demonstrated a flexible resistive random access memory device through a low-temperature atomic layer deposition process. The device is composed of an HfO2/Al2O3-based functional stack on an indium tin oxide-coated polyethylene terephthalate substrate. After the initial reset operation, the device exhibits a typical bipolar, reliable, and reproducible resistive switching behavior. After a 104-s retention time, the memory window of the device is still in accordance with excellent thermal stability, and a 10-year usage is still possible with the resistance ratio larger than 10 at room temperature and at 85°C. In addition, the operation speed of the device was estimated to be 500 ns for the reset operation and 800 ns for the set operation, which is fast enough for the usage of the memories in flexible circuits. Considering the excellent performance of the device fabricated by low-temperature atomic layer deposition, the process may promote the potential applications of oxide-based resistive random access memory in flexible integrated circuits. PMID:23421424

  15. High diffraction efficiency of three-layer diffractive optics designed for wide temperature range and large incident angle.

    PubMed

    Mao, Shan; Cui, Qingfeng; Piao, Mingxu; Zhao, Lidong

    2016-05-01

    A mathematical model of diffraction efficiency and polychromatic integral diffraction efficiency affected by environment temperature change and incident angle for three-layer diffractive optics with different dispersion materials is put forward, and its effects are analyzed. Taking optical materials N-FK5 and N-SF1 as the substrates of multilayer diffractive optics, the effect on diffraction efficiency and polychromatic integral diffraction efficiency with intermediate materials POLYCARB is analyzed with environment temperature change as well as incident angle. Therefore, three-layer diffractive optics can be applied in more wide environmental temperature ranges and larger incident angles for refractive-diffractive hybrid optical systems, which can obtain better image quality. Analysis results can be used to guide the hybrid imaging optical system design for optical engineers.

  16. Thermal annealing of radiation damage in CMOS ICs in the temperature range -140 C to +375 C

    NASA Technical Reports Server (NTRS)

    Danchenko, V.; Fang, P. H.; Brashears, S. S.

    1982-01-01

    Annealing of radiation damage was investigated in the commercial, Z- and J-processes of the RCA CD4007A ICs in the temperature range from -140 C to +375 C. Tempering curves were analyzed for activation energies of thermal annealing, following irradiation at -140 C. It was found that at -140 C, the radiation-induced shifts in the threshold potentials were similar for all three processes. The radiation hardness of the Z- and J-process is primarily due to rapid annealing of radiation damage at room temperature. In the region -140 to 20 C, no dopant-dependent charge trapping is seen, similar to that observed at higher temperatures. In the unbiased Z-process n-channels, after 1 MeV electron irradiation, considerable negative charge remains in the gate oxide.

  17. Wafer-level Au-Au bonding in the 350-450 °C temperature range

    NASA Astrophysics Data System (ADS)

    Tofteberg, Hannah R.; Schjølberg-Henriksen, Kari; Fasting, Eivind J.; Moen, Alexander S.; Taklo, Maaike M. V.; Poppe, Erik U.; Simensen, Christian J.

    2014-08-01

    Metal thermocompression bonding is a hermetic wafer-level packaging technology that facilitates vertical integration and shrinks the area used for device sealing. In this paper, Au-Au bonding at 350, 400 and 450 °C has been investigated, bonding wafers with 1 µm Au on top of 200 nm TiW. Test Si laminates with device sealing frames of 100, 200, and 400 µm in width were realized. Bond strengths measured by pull tests ranged from 8 to 102 MPa and showed that the bond strength increased with higher bonding temperatures and decreased with increasing frame width. Effects of eutectic reactions, grain growth in the Au film and stress relaxation causing buckles in the TiW film were most pronounced at 450 °C and negligible at 350 °C. Bond temperature below the Au-Si eutectic temperature 363 °C is recommended.

  18. Finite-size scaling of the critical temperatures of magnetic thin films with variable range of interactions.

    NASA Astrophysics Data System (ADS)

    Bramfeld, Timothy; Willis, Roy F.

    2006-03-01

    Finite-size scaling in magnetic (spin) systems with an arbitrary range of spin interactions was first discussed by Domb and Dalton [1]. These authors explored the effect on the various critical exponents of the thermodynamic quantities of a generalized Ising model in which each spin interacts equally strongly with neighbors within some finite interaction distance beyond which the interaction goes to zero. Such a model was used by Zhang & Willis [2] to explain the thickness dependence of the Curie temperatures of ferromagnetic nickel films. Specifically, they showed that Tc followed a power law, reduced temperature t ˜ L^-λdown to a critical thickness Lo = Ro, at which point the critical temperature reduced linearly with further decreasing thickness L. In this talk, we show that the demarcation point Lo = Ro scales with the range of spin interactions in alloy films. This parameter Ro is a function of the changing dimensions of the Fermi surface i.e. related to the period of RKKY oscillations in these itinerant ferromagnets. We examine the ramifications of an increasing range of spin interactions Ro on the finite-size critical behavior of a magnetic system. [1] C. Domb & N.W. Dalton, Proc. Phys. Soc. 89, 859 (1966). [2] R. Zhang & R.F. Willis, Phys. Rev. Lett. 86, 2665 (2001).

  19. Evaluation of reusable surface insulation for space shuttle over a range of heat-transfer rate and surface temperature

    NASA Technical Reports Server (NTRS)

    Chapman, A. J.

    1973-01-01

    Reusable surface insulation materials, which were developed as heat shields for the space shuttle, were tested over a range of conditions including heat-transfer rates between 160 and 620 kW/sq m. The lowest of these heating rates was in a range predicted for the space shuttle during reentry, and the highest was more than twice the predicted entry heating on shuttle areas where reusable surface insulation would be used. Individual specimens were tested repeatedly at increasingly severe conditions to determine the maximum heating rate and temperature capability. A silica-base material experienced only minimal degradation during repeated tests which included conditions twice as severe as predicted shuttle entry and withstood cumulative exposures three times longer than the best mullite material. Mullite-base materials cracked and experienced incipient melting at conditions within the range predicted for shuttle entry. Neither silica nor mullite materials consistently survived the test series with unbroken waterproof surfaces. Surface temperatures for a silica and a mullite material followed a trend expected for noncatalytic surfaces, whereas surface temperatures for a second mullite material appeared to follow a trend expected for a catalytic surface.

  20. Two-step sintering of new potassium sodium niobate ceramics: a high d₃₃ and wide sintering temperature range.

    PubMed

    Wu, Jiagang; Wang, Yumei

    2014-09-14

    In this work, the two-step sintering technique is used to realize a high piezoelectric constant (d33) and wide sintering temperature range (T(S)) in the 0.955(K(0.42)Na(0.58))(Nb(0.96)Sb(0.04))O3-0.045(Bi(0.5)K(0.5))(0.90)Zn(0.10)ZrO3 lead-free ceramics. Dense microstructures were developed in the ceramics by two-step sintering. In the T(S) range of 800-1130 °C, the rhombohedral-tetragonal phase boundary was well maintained, and these ceramics possess enhanced dielectric, ferroelectric, and piezoelectric properties. It is of great interest to note that a d33 of 323-416 pC/N could be attained in a temperature gap range of 330 °C. We believe that the two-step sintering could both widen the sintering temperature and obtain a high d33 for this material system. PMID:25051530

  1. Constitutive behaviour of an as-cast AA7050 alloy in the sub-solidus temperature range

    NASA Astrophysics Data System (ADS)

    Subroto, T. A. S.; Miroux, A. G.; Eskin, D. G.; Katgerman, L.

    2012-01-01

    Aluminum alloy 7050 is of interest for aerospace industries due to its superior mechanical properties. However, its inherent solidification behaviour may augment the accumulation of residual stresses due to uneven cooling conditions upon direct-chill (DC) casting. This can increase the propensity of cold cracking (CC), which is a potentially catastrophic phenomenon in casting ingots. To predict the outcome of the aluminum casting process, ALSIM software is utilised. This software has the capability to predict CC susceptibility during the casting process. However, at the moment, ALSIM lacks the information regarding material constitutive behaviour in the sub-solidus temperature range, which is considered important for studying CC phenomenon. At the moment, ALSIM only has a partial constitutive database for AA7050 and misses data, especially in the vicinity of non-equilibrium solidus (NES) point. The present work presents measurements of tensile constitutive parameters in the temperature range between 400 °C and NES, which is for this alloy defined as 465 °C. The mechanical behaviour is tested in a Gleeble 3800 thermo-mechanical simulator. Constitutive parameters such as stress-strain curves, strain-rate sensitivity and ductility of the alloy have been measured at different test temperatures. With these constitutive data, we expect to improve the accuracy of ALSIM simulations in terms of CC prediction, and gain more insight into the evolution of mechanical properties of AA7050 in the temperature nearby the NES.

  2. Assessment of some soil thermal conductivity models via variations in temperature and bulk density at low moisture range

    NASA Astrophysics Data System (ADS)

    Mahdavi, Seyed Mohamad; Neyshabouri, Mohammad Reza; Fujimaki, Haruyuki

    2016-08-01

    Simulation of heat transfer in soil under steady and unsteady situations requires reliable estimate of soil thermal conductivity (λ) at varying environmental conditions. In the current work several soil thermal conductivity predicting models including I) de Vries, II) Campbell, III) combined de Vries and Campbell and IV) de Vries-Nobre were evaluated for the four soils of coarse sand, sandy loam, loam and clay loam textured at varying in temperature and bulk density at low moisture range. Thermal conductivities measured by the cylindrical probe method served as the reference for models assessment. Results showed that approximately same thermal conductivities obtained by the five methods at low moisture range (θ ≤ 0.05 m3/m3). Also the de Vries and de Vries-Campbell models produced accurate than Campbell and de vries-Nobre models. The accuracy of the two models increased with soil compaction but decreased with temperature rise. Campbell model showed more reliability at higher (311.16 and 321.16 K) temperatures; but its accuracy declined with soil compaction in current work. It seems that assuming needle shape for the soil particles is far away from the reality whereas assuming spherical shapes may be more realistic and produced more satisfactory prediction of thermal conductivity. The compaction would alter particle arrangement and may increase the contact area of particles; and then make them behave more or less spherical shape.it seems thermal conductivity in solid particles increase via increasing in temperature. Since a modified mineral shape factor, g m , was developed as a combination between sphere and needle according to geometric mean particle diameter as well as bulk density and temperature as modifying factors. This factor increased the accuracy of de Vries-Nobre model up to 10.37%. Regarding nonlinear regression model, moisture content, bulk density, temperature and quartz content demonstrated significant effect on soil thermal conductivity in our

  3. Ab initio potentials of F+Li{sub 2} accessible at ultracold temperatures

    SciTech Connect

    Wright, K. W. A.; Lane, Ian C.

    2010-09-15

    Ab initio calculations for the strongly exoergic Li{sub 2}+F harpoon reaction are presented using density-functional theory, complete active space self-consistent field, and multireference configuration interaction methods to argue that this reaction would be an ideal candidate for investigation with ultracold molecules. The lowest six states are calculated with the aug-correlation-consistent polarized valence triple-zeta basis set and at least two can be accessed by a ground rovibronic Li{sub 2} molecule with zero collision energy at all reaction geometries. The large reactive cross section (characteristic of harpoon reactions) and chemiluminescent products are additional attractive features of these reactions.

  4. Static and Statistical Properties of Hot Rotating Nuclei in a Macroscopic Temperature-Dependent Finite-Range Model

    SciTech Connect

    Ryabov, E.G.; Adeev, G.D.

    2005-09-01

    A macroscopic temperature-dependent model that takes into account nuclear forces of finite range is used to calculate the static and statistical properties of hot rotating compound nuclei. The level-density parameter is approximated by an expression of the leptodermous type. The resulting expansion coefficients are in good agreement with their counterparts proposed previously by A.V. Ignatyuk and his colleagues. The effect of taking simultaneously into account the temperature of a nucleus and its angular momentum on the quantities under study, such as the heights and positions of fission barriers and the effective moments of inertia of nuclei at the barrier, is considered, and the importance of doing this is demonstrated. The fissility parameter (Z{sup 2}/A){sub crit} and the position of the Businaro-Gallone point are studied versus temperature. It is found that, with increasing temperature, both parameters are shifted to the region of lighter nuclei. It is shown that the inclusion of temperature leads to qualitatively the same effects as the inclusion of the angular momentum of a nucleus, but, quantitatively, thermal excitation leads to smaller effects than rotational excitation.

  5. Improvement of Surface Temperature Prediction Using SVR with MOGREPS Data for Short and Medium range over South Korea

    NASA Astrophysics Data System (ADS)

    Lim, S. J.; Choi, R. K.; Ahn, K. D.; Ha, J. C.; Cho, C. H.

    2014-12-01

    As the Korea Meteorology Administration (KMA) has operated Met Office Global and Regional Ensemble Prediction System (MOGREPS) with introduction of Unified Model (UM), many attempts have been made to improve predictability in temperature forecast in last years. In this study, post-processing method of MOGREPS for surface temperature prediction is developed with machine learning over 52 locations in South Korea. Past 60-day lag time was used as a training phase of Support Vector Regression (SVR) method for surface temperature forecast model. The selected inputs for SVR are followings: date and surface temperatures from Numerical Weather prediction (NWP), such as GDAPS, individual 24 ensemble members, mean and median of ensemble members for every 3hours for 12 days.To verify the reliability of SVR-based ensemble prediction (SVR-EP), 93 days are used (from March 1 to May 31, 2014). The result yielded improvement of SVR-EP by RMSE value of 16 % throughout entire prediction period against conventional ensemble prediction (EP). In particular, short range predictability of SVR-EP resulted in 18.7% better RMSE for 1~3 day forecast. The mean temperature bias between SVR-EP and EP at all test locations showed around 0.36°C and 1.36°C, respectively. SVR-EP is currently extending for more vigorous sensitivity test, such as increasing training phase and optimizing machine learning model.

  6. Critical temperature ranges of hypothermia-induced platelet activation: possible implications for cooling patients in cardiac surgery.

    PubMed

    Straub, Andreas; Breuer, Melanie; Wendel, Hans P; Peter, Karlheinz; Dietz, Klaus; Ziemer, Gerhard

    2007-04-01

    Cooling of the patient is routinely applied in cardiac surgery to protect organs against ischemia. Hypothermia induces activation of platelets, but the effects of temperatures such as used during cardiac surgery are not well described. To investigate this in an in-vitro study heparinized whole blood was incubated at different temperatures (37 degrees C, 34.5 degrees C, 32 degrees C, 29.5 degrees C, 27 degrees C, 24.5 degrees C, 22 degrees C, 19.5 degrees C and 17 degrees C). The effect of these temperatures on aggregation, P-selectin expression, GP IIb/IIIa activation and platelet microparticle (PMP) formation of unstimulated and ADP-stimulated platelets of 36 subjects was evaluated in flow cytometry. A four-parametric logistic model was fitted to depict the temperature effect on platelet parameters. Lower temperatures increased aggregates, P-selectin expression, and GP IIb/IIIa activation. The number of PMPs decreases with hypothermia. Additional experiments revealed a slight influence of heparin on platelet P-selectin expression but excluded an effect of this anticoagulant on the other evaluated parameters. Threshold temperatures, which mark 5% changes of platelet parameters compared to values at 37 degrees C, were calculated. On ADP-stimulated platelets the thresholds for P-selectin expression and GP IIb/IIa activation are 34.0 degrees C and 36.4 degrees C, respectively, and lie in the temperature range routinely applied in cardiac surgery. Hypothermia-induced platelet activation may develop in most patients undergoing cardiac surgery, possibly resulting in thromboembolic events, coagulation defects, and proinflammatory leukocyte bridging by P-selectin bearing platelets and PMPs. These findings suggest that pharmacological protection of platelets against hypothermia-induced damage may be beneficial during cardiac surgery.

  7. Design Strategies for Optically-Accessible, High-Temperature, High-Pressure Reactor

    SciTech Connect

    S. F. Rice; R. R. Steeper; C. A. LaJeunesse; R. G. Hanush; J. D. Aiken

    2000-02-01

    The authors have developed two optical cell designs for high-pressure and high-temperature fluid research: one for flow systems, and the other for larger batch systems. The flow system design uses spring washers to balance the unequal thermal expansions of the reactor and the window materials. A typical design calculation is presented showing the relationship between system pressure, operating temperature, and torque applied to the window-retaining nut. The second design employs a different strategy more appropriate for larger windows. This design uses two seals: one for the window that benefits from system pressure, and a second one that relies on knife-edge, metal-to-metal contact.

  8. Design strategies for optically-accessible, high-temperature, high-pressure reactor

    SciTech Connect

    S. F. Rice; R. R. Steeper; C. A. LaJeunesse; R. G. Hanush; J. D. Aiken

    2000-02-01

    The authors have developed two optical cell designs for high-pressure and high-temperature fluid research: one for flow systems, and the other for larger batch systems. The flow system design uses spring washers to balance the unequal thermal expansions of the reactor and the window materials. A typical design calculation is presented showing the relationship between system pressure, operating temperature, and torque applied to the window-retaining nut. The second design employs a different strategy more appropriate for larger windows. This design uses two seals: one for the window that benefits from system pressure, and a second one that relies on knife-edge, metal-to-metal contact.

  9. Communication: Temperature derivative of the dielectric constant gives access to multipoint correlations in polar liquids.

    PubMed

    Matyushov, Dmitry V; Richert, Ranko

    2016-01-28

    Fluctuations of the dipole moment of a macroscopic dielectric sample are induced by thermal motions. The variance of the sample dipole moment, characterizing the extent of thermal fluctuations, is a decaying function of temperature for many polar liquids. This result is inconsistent with the Nyquist (fluctuation-dissipation) theorem predicting the variance of a macroscopic property to grow linearly with temperature. The reason for a qualitatively different behavior is in strong multi-particle correlations of dipolar orientations. An equation connecting the temperature slope of the dielectric constant to a static three-point correlation function is derived. When applied to experimental data for polar and hydrogen-bonding liquids at normal conditions, the three-point correlations of different liquids fall on a single master curve as a function of the dielectric constant. Static three-point correlation functions can potentially reflect the growing spatial correlation length on approach to the glass transition. However, the measured temperature slope of the dielectric constant of glycerol does not indicate a change in such a lengthscale.

  10. Communication: Temperature derivative of the dielectric constant gives access to multipoint correlations in polar liquids

    NASA Astrophysics Data System (ADS)

    Matyushov, Dmitry V.; Richert, Ranko

    2016-01-01

    Fluctuations of the dipole moment of a macroscopic dielectric sample are induced by thermal motions. The variance of the sample dipole moment, characterizing the extent of thermal fluctuations, is a decaying function of temperature for many polar liquids. This result is inconsistent with the Nyquist (fluctuation-dissipation) theorem predicting the variance of a macroscopic property to grow linearly with temperature. The reason for a qualitatively different behavior is in strong multi-particle correlations of dipolar orientations. An equation connecting the temperature slope of the dielectric constant to a static three-point correlation function is derived. When applied to experimental data for polar and hydrogen-bonding liquids at normal conditions, the three-point correlations of different liquids fall on a single master curve as a function of the dielectric constant. Static three-point correlation functions can potentially reflect the growing spatial correlation length on approach to the glass transition. However, the measured temperature slope of the dielectric constant of glycerol does not indicate a change in such a lengthscale.

  11. The Current-Voltage Characteristics of the Au/MBEn-GaAs Schottky Diodes in a Wide Temperature Range

    NASA Astrophysics Data System (ADS)

    EfeoǦLU, Hasan; Turut, Abdulmecit

    2013-07-01

    The Au/MBEn-GaAs Schottky diodes have been fabricated by us. The slope of the conventional ln(I0/T2) versus (kT)-1 plotted in the temperature range of 120-350 K has given a Richardson constant (RC) of 7.69 A (cmK)-2 which is in close agreement with the value of 8.16 A/cm2K2 known for n-type GaAs. The barrier height (BH) value in 40-160 K range has decreased obeying to Gaussian distribution (GD) model of the BH based on thermionic emission current theory. The modified RC plot according to the GD model has given a RC value of 2.45 A (cmK)-2 or a value of 2.38 A (cmK)-2 by taking into account the temperature dependence of the standard deviation. Therefore, we have modified the Richardson's plot using the temperature dependent values of the effective area of the patches introduced by lateral inhomogeneity of the BHs and we have obtained a RC value of 8.10 A (cmK)-2.

  12. The thermodynamic properties of 2-ethylhexyl acrylate over the temperature range from T → 0 to 350 K

    NASA Astrophysics Data System (ADS)

    Kulagina, T. G.; Samosudova, Ya. S.; Letyanina, I. A.; Sevast'yanov, E. V.; Smirnova, N. N.; Smirnova, L. A.; Mochalova, A. E.

    2012-05-01

    The temperature dependence of the heat capacity C {/p o}= f( T) 2 of 2-ethylhexyl acrylate was studied in an adiabatic vacuum calorimeter over the temperature range 6-350 K. Measurement errors were mainly of 0.2%. Glass formation and vitreous state parameters were determined. An isothermic shell calorimeter with a static bomb was used to measure the energy of combustion of 2-ethylhexyl acrylate. The experimental data were used to calculate the standard thermodynamic functions C {/p o}( T), H o( T)- H o(0), S o( T)- S o(0), and G o( T)- H o(0) of the compound in the vitreous and liquid states over the temperature range from T → 0 to 350 K, the standard enthalpies of combustion Δc H o, and the thermodynamic characteristics of formation Δf H o, Δf S o, and Δf G o at 298.15 K and p = 0.1 MPa.

  13. Kinetic measurements on elementary fossil fuel combustion reactions over wide temperatures ranges. Progress report, December 1, 1990--November 30, 1991

    SciTech Connect

    Fontijin, A.

    1992-01-01

    The goals of this work are to provide accurate data on the temperature dependence of the kinetics of elementary combustion reactions (i) for use by combustion modelers, and (ii) to gain a better fundamental understanding of, and hence predictive ability for, the chemistry involved. Experimental measurements are made using the pseudo-static HTP (high-temperature photochemistry) technique. This approach allows observations on single reactions in the 300 to 1800 K temperature range to be made. Typical total (bath gas) pressures are in the 100 to 1000 mbar range. Ground-state O and H atoms are produced by flash or excimer laser photolysis of suitable precursors (O{sub 2}, CO{sub 2}, SO{sub 2}, NH{sub 3}). The relative atom concentrations are monitored by resonance fluorescence pumped by a cw microwave discharge flow lamp. The molecular reactant-in-excess is introduced through a cooled inlet. Adequate time for mixing, 0.1 to 10 s, between this inlet and the photolysis/observation zone is achieved by using slow flows (typically less than 20 cm s{sup {minus}1}). Results are reported for: O-Atom Reactions with the Four Isomeric Butenes, H + HCl {yields} H{sub 2} + Cl, and the O-atom 1,3-butadiene reaction.

  14. Aerial perches and free-range laying hens: the effect of access to aerial perches and of individual bird parameters on keel bone injuries in commercial free-range laying hens.

    PubMed

    Donaldson, C J; Ball, M E E; O'Connell, N E

    2012-02-01

    The aim of this trial was to determine the effect of aerial perches on keel bone injuries and tibia bone characteristics in free-range laying hens. The relationship between keel bone injuries and individual bird parameters, such as weight, girth, wing:girth ratio, feather coverage, and tibia bone characteristics, was also assessed. Five commercial free-range houses, each containing between 7,000 and 8,000 birds, were used. The houses and range areas were divided in half; in half of the house, birds had access to aerial perches (P) and in the other half, they did not (NP). On 13 occasions between 17 and 70 wk of age, 20 birds per treatment were randomly selected from the slatted area and palpated for keel bone injury. At 72 wk of age, 30 birds per treatment in each of 4 houses were selected at random, weighed, and then euthanized. Girth and wing area and feather coverage were measured. The keel and left tibia bones were removed and keel bones were scored for injury. Tibia bones were weighed and diameter, length, breaking strength, and ash content recorded. Results indicated that access to aerial perches did not affect tibia bone measures (P > 0.05). Average palpated keel bone score increased with age of the hens (P < 0.001) but was not significantly affected by perch treatment (P > 0.05). There was a significant interaction between treatment and farm on keel bone injuries measured at dissection (P < 0.05), with the probability of birds having high keel-damage scores increasing in the perched treatment in some farms but not others. In general, as the keel bone injury score measured at dissection increased, the breaking strength (P < 0.001) and ash content (P < 0.05) of the tibia bone decreased. It is suggested that individual variation in bone strength contributes to differences in susceptibility to keel injury. No relationship existed between keel-injury score measured at dissection and individual parameters, such as weight, girth, or wing:girth ratio (P > 0

  15. Simultaneous measurement of all thermoelectric properties of bulk materials in the temperature range 300-600 K.

    PubMed

    Kolb, H; Dasgupta, T; Zabrocki, K; Mueller, E; de Boor, J

    2015-07-01

    Thermoelectric materials can directly convert heat into electrical energy. The characterization of different materials is an important part in thermoelectric materials research to improve their properties. Usually, different methods and setups are combined for the temperature dependent determination of all thermoelectric key quantities - Seebeck coefficient, electrical conductivity, and thermal conductivity. Here, we present a measurement system for the simultaneous determination of all of these quantities plus the direct determination of the figure of merit by means of the Harman method (zT)H in a temperature range from room temperature up to 600 K. A simultaneous measurement saves time and reduces the measurement error, and the change of all material properties can be monitored even for unstable materials. Thermal conductivity measurements are inherently affected by undesired thermal losses, in particular, through radiation at higher temperatures. We show a simple experimental approach to measure radiation losses and correct for those. Comparative measurements on traditional systems show good agreement for all measured quantities. PMID:26233393

  16. Relation between martensitic transformation temperature range and lattice distortion ratio of NiMnGaCoCu Heusler alloys

    NASA Astrophysics Data System (ADS)

    Wei, Jun; Xie, Ren; Chen, Le-Yi; Tang, Yan-Mei; Xu, Lian-Qiang; Tang, Shao-Long; Du, You-Wei

    2014-04-01

    In order to study the relation between martensitic transformation temperature range ΔT (where ΔT is the difference between martensitic transformation start and finish temperature) and lattice distortion ratio (c/a) of martensitic transformation, a series of Ni46Mn28-xGa22Co4Cux (x = 2-5) Heusler alloys is prepared by arc melting method. The vibration sample magnetometer (VSM) experiment results show that ΔT increases when x > 4 and decreases when x < 4 with x increasing, and the minimal ΔT (about 1 K) is found at x = 4. Ambient X-ray diffraction (XRD) results show that ΔT is proportional to c/a for non-modulated Ni46Mn28-xGa22Co4Cux (x = 2-5) martensites. The relation between ΔT and c/a is in agreement with the analysis result obtained from crystal lattice mismatch model. About 1000-ppm strain is found for the sample at x = 4 when heating temperature increases from 323 K to 324 K. These properties, which allow a modulation of ΔT and temperature-induced strain during martensitic transformation, suggest Ni46Mn24Ga22Co4Cu4 can be a promising actuator and sensor.

  17. Thermal effects in the DKDP Pockels cells in the 215-300  K temperature range.

    PubMed

    Starobor, Aleksey; Palashov, Oleg

    2016-09-10

    The thermal and electro-optical effects in Pockels cells with deuterated potassium dihydrogen phosphate (DKDP) crystals in the 215-300 K temperature range were investigated. Half-wave voltage decreases linearly with cooling, thereby it reduces seven times (up to 1 kW) with cooling to 215 K. The optical power of the thermally induced lens falls twice on cooling to 215 K from 300 K; thermally induced depolarization is almost independent of temperature and determined by input radiation power. A significant reduction of the thermally induced depolarization in a DKDP crystal with the axis inclined to the polarization plane of the beam was demonstrated numerically and experimentally. Thus, the DKDP crystals cooled to 215 K allow the creation of a low-voltage Pockels cell working with a high average and peak laser power. PMID:27661375

  18. A borinic acid polymer with fluoride ion- and thermo-responsive properties that are tunable over a wide temperature range.

    PubMed

    Wan, Wen-Ming; Cheng, Fei; Jäkle, Frieder

    2014-08-18

    A new type of smart borinic acid polymer with luminescence and multiple stimuli-responsive properties is reported. In DMSO with small amounts of water, the homopolymer PBA shows a tunable upper critical solution temperature (UCST). As the amount of water increases from 0 to 2.5 % (v/v), the UCST rises linearly from 20 °C to 100 °C (boiling point of water). Thus, the thermal responsive behavior can be tuned over a wide temperature range. Furthermore, polymer solutions in DMSO show a reversible response to fluoride ions, which can be correlated to the presence of the Lewis acidic borinic acid groups. Upon addition of fluoride, the polymer becomes soluble because the functional R2BOH groups are converted into ionic [R2BF2](-) groups, but turns insoluble again upon addition of H2O, which reverses this process.

  19. A PdMn Based High Resolution Thermometer for the Temperature Range of 0.7-1 K

    NASA Technical Reports Server (NTRS)

    Koo, Peter K.

    2005-01-01

    Experiments Along the Coexistence near Tricriticality (EXACT) will test exact predictions made by Renormalization Group theory by mapping the phase diagram of liquid He-3 and He-4 mixtures at the tricritical point, Tcp=0.867 K. A PdMn based High Resolution Thermometer (HRT) will be utilized by EXACT to make accurate measurements with a resolution that has never been attained for the temperature range 0.7-1 K. The basic design of this mini high resolution thermometer comprises a sensing element whose magnetic susceptibility changes with temperature, a thermal connector, magnetic shielding, and some permanent magnets to apply a constant magnetic field. In this study, we will quantitatively determine the resolution of possible sensing element candidates of 0.15%, 0.20%, and 0.25% ppm Mn and compare them with an annealed group of PdMn with the corresponding concentrations to see how this processing technique affects sensitivity.

  20. Recrystallization kinetics of warm-rolled tungsten in the temperature range 1150-1350 °C

    NASA Astrophysics Data System (ADS)

    Alfonso, A.; Juul Jensen, D.; Luo, G.-N.; Pantleon, W.

    2014-12-01

    Pure tungsten is a potential candidate material for the plasma-facing first wall and the divertor of fusion reactors. Both parts have to withstand high temperatures during service. This will alter the microstructure of the material by recovery, recrystallization and grain growth and will cause degradation in material properties as a loss in mechanical strength and embrittlement. The thermal stability of a pure tungsten plate warm-rolled to 67% thickness reduction was investigated by long-term isothermal annealing in the temperature range between 1150 °C and 1350 °C up to 2200 h. Changes in the mechanical properties during annealing are quantified by Vickers hardness measurements. They are described concisely by classical kinetic models for recovery and recrystallization. The observed time spans for recrystallization and the obtained value for the activation energy of the recrystallization process indicate a sufficient thermal stability of the tungsten plate during operation below 1075 °C.

  1. Measurement of performance of thermoacoustic heat pump in a -3 to 160 °C temperature range

    NASA Astrophysics Data System (ADS)

    Kikuchi, Ryo; Tsuda, Kenichiro; Bassem, Mohamed Mehdi; Ueda, Yuki

    2015-11-01

    A thermoacoustic heat pump was constructed and tested. It was composed of a looped tube, a straight tube, and a regenerator. The looped tube contained the regenerator and was connected to the straight tube. The tubes were filled with nitrogen. When an acoustic wave was input to the tubes, a temperature difference formed along the regenerator. Our experiments showed that this heat pump could work as both a cooler and a heater. This heat pump achieved -39 °C as a cooler and 270 °C as a heater. Using antifreeze liquid and oil as heat media, the cooling and heating performance of the heat pump was measured within the temperature range from -3 to 160 °C.

  2. Oxygen nonstoichiometry and thermodynamic characterization of Zr doped ceria in the 1573-1773 K temperature range.

    PubMed

    Takacs, M; Scheffe, J R; Steinfeld, A

    2015-03-28

    This work encompasses the thermodynamic characterization and critical evaluation of Zr(4+) doped ceria, a promising redox material for the two-step solar thermochemical splitting of H2O and CO2 to H2 and CO. As a case study, we experimentally examine 5 mol% Zr(4+) doped ceria and present oxygen nonstoichiometry measurements at elevated temperatures ranging from 1573 K to 1773 K and oxygen partial pressures ranging from 4.50 × 10(-3) atm to 2.3 × 10(-4) atm, yielding higher reduction extents compared to those of pure ceria under all conditions investigated, especially at the lower temperature range and at higher pO2. In contrast to pure ceria, a simple ideal solution model accounting for the formation of isolated oxygen vacancies and localized electrons accurately describes the defect chemistry. Thermodynamic properties are determined, namely: partial molar enthalpy, entropy, and Gibbs free energy. In general, partial molar enthalpy and entropy values of Zr(4+) doped ceria are lower. The equilibrium hydrogen yields are subsequently extracted as a function of the redox conditions for dopant concentrations as high as 20%. Although reduction extents increase greatly with dopant concentration, the oxidation of Zr(4+) doped ceria is thermodynamically less favorable compared to pure ceria. This leads to substantially larger temperature swings between reduction and oxidation steps, ultimately resulting in lower theoretical solar energy conversion efficiencies compared to ceria under most conditions. In effect, these results point to the importance of considering oxidation thermodynamics in addition to reduction when screening potential redox materials.

  3. Elevation-dependent temperature trends in the Rocky Mountain Front Range: changes over a 56- and 20-year record.

    PubMed

    McGuire, Chris R; Nufio, César R; Bowers, M Deane; Guralnick, Robert P

    2012-01-01

    Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953-2008) and a shorter 20-year (1989-2008) record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM) datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data, we caution against

  4. The correlation between dengue incidence and diurnal ranges of temperature of Colombo district, Sri Lanka 2005–2014

    PubMed Central

    Ehelepola, N. D. B.; Ariyaratne, Kusalika

    2016-01-01

    Background Meteorological factors affect dengue transmission. Mechanisms of the way in which different diurnal temperatures, ranging around different mean temperatures, influence dengue transmission were published after 2011. Objective We endeavored to determine the correlation between dengue incidence and diurnal temperature ranges (DTRs) in Colombo district, Sri Lanka, and to explore the possibilities of using our findings to improve control of dengue. Design We calculated the weekly dengue incidence in Colombo during 2005–2014, after data on all of the reported dengue patients and estimated mid-year populations were collected. We obtained daily maximum and minimum temperatures from two Colombo weather stations, averaged, and converted them into weekly data. Weekly averages of DTR versus dengue incidence graphs were plotted and correlations observed. The count of days per week with a DTR of >7.5°C and <7.5°C were also calculated. Wavelet time series analysis was performed to determine the correlation between dengue incidence and DTR. Results We obtained a negative correlation between dengue incidence and a DTR>7.5°C with an 8-week lag period, and a positive correlation between dengue incidence and a DTR<7.5°C, also with an 8-week lag. Conclusions Large DTRs were negatively correlated with dengue transmission in Colombo district. We propose to take advantage of that in local dengue control efforts. Our results agree with previous studies on the topic and with a mathematical model of relative vectorial capacity of Aedes aegypti. Global warming and declining DTR are likely to favor a rise of dengue, and we suggest a simple method to mitigate this. PMID:27566717

  5. Calibrating a new proxy for Pleistocene climate change in southern Africa: the Mutual Ostracod Temperature Range method

    NASA Astrophysics Data System (ADS)

    Horne, David; Martens, Koen

    2010-05-01

    The Mutual Ostracod Temperature Range (MOTR) method has so far been applied only in the European Pleistocene, where it is proving effective in producing past air temperature range estimates that compare well with those obtained by other proxy methods (Horne, 2007; Horne & Mezquita, 2008; Holmes et al., in press). As an essential preliminary step towards applying the method in southern Africa, we have calibrated a training set of living ostracod species' distributions against a modern climate dataset and other available environmental data. The modern ostracod dataset is based on material held by the Royal Belgian Institute of Natural Sciences in Brussels, which constitutes the most diverse and comprehensive collection of southern African nonmarine ostracods available anywhere in the world. To date, c. 150 nominal species have been described from southern Africa (Martens, 2001) out of c. 450 species in the total Afrotropical area (Martens et al., 2008). We used an edited dataset comprising a total of 2,118 records of ostracod species from 748 localities in southern Africa, ranging in latitude from approximately 17 degrees S to 35 degrees S. We have explored the potential value and limitations of this training set for the estimation of past climatic parameters including mean July, January and annual air temperatures, precipitation, water conductivity and pH. Holmes, J. A., Atkinson, T., Darbyshire, D. P. F., Horne, D. J., Joordens, J., Roberts, M. B., Sinka, K. J. & Whittaker, J. E. (accepted, in press). Middle Pleistocene climate and hydrological environment at the Boxgrove hominin site (West Sussex, UK) from ostracod records. Quaternary Science Reviews, doi:10.1016/j.quascirev.2009.02.024, 1-13. Horne, D. J. 2007. A Mutual Temperature Range method for Quaternary palaeoclimatic analysis using European nonmarine Ostracoda. Quaternary Science Reviews, 26, 1398-1415. Horne, D. J. & Mezquita, F. 2008. Palaeoclimatic applications of large databases: developing and testing

  6. Raman spectroscopy of SrB4O7 single crystals in the temperature range 300-1273 K

    NASA Astrophysics Data System (ADS)

    Sobol, A. A.; Shukshin, V. E.; Zaitsev, A. I.

    2016-07-01

    The polarized Raman spectra of SrB4O7 (SBO) single crystals are studied in detail in the temperature range of 300-1273 K. The TO, LO, and IO phonon lines of A 1, A 2, B 1, and B 2 symmetries of rhombic SBO at 300 K are identified. The behavior of the Raman spectra of SBO crystals is studied upon heating up to their melting. The relation of Raman spectra with the structure of boron-oxygen fragments, as well as the transformation of spectra in the process of melting of SBO crystals, is discussed.

  7. Evaluation of simulated climatological diurnal temperature range in CMIP5 models from the perspective of planetary boundary layer turbulent mixing

    NASA Astrophysics Data System (ADS)

    Wei, Nan; Zhou, Liming; Dai, Yongjiu

    2016-08-01

    This study examines the effects of modeled planetary boundary layer (PBL) mixing on the simulated temperature diurnal cycle climatology over land in 20 CMIP5 models with AMIP simulations. When compared with observations, the magnitude of diurnal temperature range (DTR) is systematically underestimated over almost all land areas due to a widespread warm bias of daily minimum temperature (Tmin) and mostly a cold bias of daily maximum temperature (Tmax). Analyses of the CMIP5 multi-model ensemble means suggest that the biases of the simulated PBL mixing could very likely contribute to the temperature biases. For the regions with the cold bias in Tmax, the daytime PBL mixing is generally underestimated. The consequent more dry air entrainment from the free atmosphere could help maintain the surface humidity gradient, and thus produce more surface evaporation and potentially lower the Tmax. The opposite situation holds true for the regions with the warm bias of Tmax. This mechanism could be particularly applicable to the regions with moderate and wet climate conditions where surface evaporation depends more on the surface humidity gradient, but less on the available soil moisture. For the widespread warm bias of Tmin, the widely-recognized overestimated PBL mixing at nighttime should play a dominant role by transferring more heat from the atmosphere to the near-surface to warm the Tmin. Further analyses using the high resolution CFMIP2 output also support the CMIP5 results about the connections of the biases between the simulated turbulent mixing and the temperature diurnal cycle. The large inter-model variations of the simulated temperature diurnal cycle primarily appear over the arid and semi-arid regions and boreal arctic regions where the model differences in the PBL turbulence mixing could make equally significant contributions to the inter-model variations of DTR, Tmax and Tmin compared to the model differences in surface radiative processes. These results

  8. Three Agt1 transporters from brewer's yeasts exhibit different temperature dependencies for maltose transport over the range of brewery temperatures (0–20 °C).

    PubMed

    Vidgren, Virve; Viljanen, Kaarina; Mattinen, Laura; Rautio, Jari; Londesborough, John

    2014-06-01

    Zero-trans rates of maltose transport by brewer's yeasts exert strong control over fermentation rates and are strongly temperature-dependent over the temperature range (20–0 °C) of brewery fermentations. Three α-glucoside transporters, ScAgt1(A60) (a Saccharomyces cerevisiae version of Agt1 from an ale strain), ScAgt1-A548V (a variant of ScAgt1(A60) with a single amino acid change in a transmembrane domain), and SbAgt1 (a Saccharomyces (eu)bayanus version from a lager strain), were compared. When expressed in the same laboratory yeast, grown at 24 °C and assayed at 0, 10, and 20 °C, SbAgt1 had the lowest absolute maltose uptake activity at 20 °C but smallest temperature dependence, ScAgt1-A548V had the highest activity but greatest temperature dependence, and ScAgt1(A60) had intermediate properties. ScAgt1(A60) exhibited higher absolute rates and smaller temperature dependencies when expressed in laboratory rather than brewer's strains. Absolute rates closely reflected the amounts of GFP-tagged ScAgt1(A60) transporter in each host's plasma membrane. Growth at 15 °C instead of 24 °C decreased the absolute activities of strains expressing ScAgt1(A60) by two- to threefold. Evidently, the kinetic characteristics of at least ScAgt1(A60) depended on the nature of the host plasma membrane. However, no consistent correlation was observed between transport activities and fatty acid or ergosterol compositions. PMID:25035870

  9. Live cell plasma membranes do not exhibit a miscibility phase transition over a wide range of temperatures.

    PubMed

    Lee, Il-Hyung; Saha, Suvrajit; Polley, Anirban; Huang, Hector; Mayor, Satyajit; Rao, Madan; Groves, Jay T

    2015-03-26

    Lipid/cholesterol mixtures derived from cell membranes as well as their synthetic reconstitutions exhibit well-defined miscibility phase transitions and critical phenomena near physiological temperatures. This suggests that lipid/cholesterol-mediated phase separation plays a role in the organization of live cell membranes. However, macroscopic lipid-phase separation is not generally observed in cell membranes, and the degree to which properties of isolated lipid mixtures are preserved in the cell membrane remain unknown. A fundamental property of phase transitions is that the variation of tagged particle diffusion with temperature exhibits an abrupt change as the system passes through the transition, even when the two phases are distributed in a nanometer-scale emulsion. We support this using a variety of Monte Carlo and atomistic simulations on model lipid membrane systems. However, temperature-dependent fluorescence correlation spectroscopy of labeled lipids and membrane-anchored proteins in live cell membranes shows a consistently smooth increase in the diffusion coefficient as a function of temperature. We find no evidence of a discrete miscibility phase transition throughout a wide range of temperatures: 14-37 °C. This contrasts the behavior of giant plasma membrane vesicles (GPMVs) blebbed from the same cells, which do exhibit phase transitions and macroscopic phase separation. Fluorescence lifetime analysis of a DiI probe in both cases reveals a significant environmental difference between the live cell and the GPMV. Taken together, these data suggest the live cell membrane may avoid the miscibility phase transition inherent to its lipid constituents by actively regulating physical parameters, such as tension, in the membrane.

  10. Modeling and Simulation of - and Silicon Germanium-Base Bipolar Transistors Operating at a Wide Range of Temperatures.

    NASA Astrophysics Data System (ADS)

    Shaheed, M. Reaz

    1995-01-01

    to provide consistently accurate values for base sheet resistance for both Si- and SiGe-base transistors over a wide range of temperatures. A model for plasma-induced bandgap narrowing suitable for implementation in a numerical simulator has been developed. The appropriate method of incorporating this model in a drift -diffusion solver is described. The importance of including this model for low temperature simulation is demonstrated. With these models in place, the enhanced simulator has been used for evaluating and designing the Si- and SiGe-base bipolar transistors. Silicon-germanium heterojunction bipolar transistors offer significant performance and cost advantages over conventional technologies in the production of integrated circuits for communications, computer and transportation applications. Their high frequency performance at low cost, will find widespread use in the currently exploding wireless communication market. However, the high performance SiGe-base transistors are prone to have a low common-emitter breakdown voltage. In this dissertation, a modification in the collector design is proposed for improving the breakdown voltage without sacrificing the high frequency performance. A comprehensive simulation study of p-n-p SiGe-base transistors has been performed. Different figures of merit such as drive current, current gain, cut -off frequency and Early voltage were compared between a graded germanium profile and an abrupt germanium profile. The differences in the performance level between the two profiles diminishes as the base width is scaled down.

  11. The laws of deformation of an amorphous polyimide (PI) film when it is stretched in the temperature range 1.6-300 K

    NASA Astrophysics Data System (ADS)

    Soldatov, V. P.; Kirichenko, G. I.; Abraimov, V. V.; Braude, I. S.; Geidarov, V. G.

    2016-09-01

    A first-time presentation of a wide range of charts imaging the stretch of amorphous polyimide (PI) film samples in the 300-1.6 K temperature range and an analysis of how temperature affects the conditional limit of fluidity, strength, and deformation of this film at the indicated temperatures. The athermal character of the breaking stress below the temperature of liquid nitrogen and its thermally activated behavior above 80 K are demonstrated. We also analyze the features of the behavior of glassy PI film samples that are stretched at low temperatures and then unloaded and warmed up to room temperatures.

  12. Amylose Phase Composition As Analyzed By FTIR In A Temperature Ramp: Influence Of Short Range Order On The Thermodynamic Properties

    NASA Astrophysics Data System (ADS)

    Bernazzani, Paul; Delmas, Genevieve

    1998-03-01

    Amylose, a major component of starch, is one of the most important biopolymers, being mainly associated with the pharmacological and food industries. Although widely studied, a complete control and understanding of the physical properties of amylose is still lacking. It is well known that structure and phase transition are important aspects of the functionality of biopolymers since they influence physical attributes such as appearance, digestibility, water holding capacity, etc. In the past, we have studied polyethylene phase composition by DSC in a very slow temperature (T) ramp (1K/h) and have demonstrated the presence and importance of short-range order on the polymer and its characteristics. In this study, we evaluated the phase composition of potato amylose and associated the thermodynamic properties with the presence of short-range order. Two methods were correlated, DSC (in a 1K/h T-ramp) and FTIR as a function of temperature, also in a 1K/h T-ramp. The effects of the various phases on thermodynamic properties such as gelation and enzyme or chemical resistance are discussed.

  13. Pressurized ion chamber monitoring system for environmental radiation measurements utilizing a wide-range temperature-compensated electrometer

    NASA Astrophysics Data System (ADS)

    van Steveninck, William

    1994-08-01

    The performance of a complete pressurized ion chamber (PIC) radiation monitoring system is described. The design incorporates an improved temperature-compensated electrometer which is stable to +/- 3 center-dot 10(sup - 16) A over the environmental range of temperature (- 40 to + 40 C). Using a single 10(sup 11) Omega feed-back resistor, the electrometer accurately measures currents over a range from 3 center-dot 10(sup - 15) A to 3 center-dot 10(sup - 11) A. While retaining the sensitivity of the original PIC system (the instrument responds readily to small background fluctuations on the order of 0.1 mu R h(sup - 1)), the new system measures radiation levels up to the point where the collection efficiency of the ion chamber begins to drop off, typically approximately 27 pA at 1 mR h(sup - 1). A data recorder and system controller was designed using the Tattletale(sup TM) Model 4A computer. Digital data is stored on removable solid-state, credit-card style memory cards.

  14. Development of Superior Sorbents for Separation of CO2 from Flue Gas at a Wide Temperature range during Coal Combustion

    SciTech Connect

    Panagiotis Smirniotis

    2002-09-17

    A number basic sorbents based on CaO were synthesized, characterized with novel techniques and tested for sorption of CO{sub 2} and selected gas mixtures simulating flue gas from coal fired boilers. Our studies resulted in highly promising sorbents which demonstrated zero affinity for N{sub 2}, O{sub 2}, SO{sub 2}, and NO very low affinity for water, ultrahigh CO{sub 2} sorption capacities, and rapid sorption characteristics, CO{sub 2} sorption at a very wide temperature range, durability, and low synthesis cost. One of the 'key' characteristics of the proposed materials is the fact that we can control very accurately their basicity (optimum number of basic sites of the appropriate strength) which allows for the selective chemisorption of CO{sub 2} at a wide range of temperatures. These unique characteristics of this family of sorbents offer high promise for development of advanced industrial sorbents for the effective CO{sub 2} removal.

  15. Performance Demonstration of Mcmb-LiNiCoO2 Cells Containing Electrolytes Designed for Wide Operating Temperature Range

    NASA Technical Reports Server (NTRS)

    Smart, M. C.; Ratnakumar, B. V.; Whicanack, L. D.; Smith, K. A.; Santee, S.; Puglia, F. J.; Gitzendanner, R.

    2009-01-01

    With the intent of improving the performance of Li-ion cells over a wide operating temperature range, we have investigated the use of co-solvents to improve the properties of electrolyte formulations. In the current study, we have focused upon evaluating promising electrolytes which have been incorporated into large capacity (7 Ah) prototype Li-ion cells, fabricated by Yardney Technical Products, Inc. The electrolytes selected for performance evaluation include the use of a number of esters as co-solvents, including methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), propyl butyrate (PB), and 2,2,2-trifluoroethyl butyrate (TFEB). The performance of the prototype cells containing the ester-based electrolytes was compared with an extensive data base generated on cells containing previously developed all carbonate-based electrolytes. A number of performance tests were performed, including determining (i) the discharge rate capacity over a wide range of temperatures, (ii) the charge characteristics, (iii) the cycle life characteristics under various conditions, and (iv) the impedance characteristics.

  16. Measurement of density, temperature, and electrical conductivity of a shock-compressed nonideal nitrogen plasma in the megabar pressure range

    SciTech Connect

    Mochalov, M. A.; Zhernokletov, M. V.; Il'kaev, R. I.; Mikhailov, A. L.; Fortov, V. E.; Gryaznov, V. K.; Iosilevskiy, I. L.; Mezhevov, A. B.; Kovalev, A. E.; Kirshanov, S. I.; Grigor'eva, Yu. A.; Novikov, M. G.; Shuikin, A. N.

    2010-01-15

    Kinematic and thermodynamic parameters of shock-compressed liquid nitrogen are measured behind the front of a plane shock wave using plane wave and hemispherical shock wave generators. In these experiments, high values of compression parameters (shock-compressed hydrogen density {approx} 3.25 g/cm{sup 3} and temperature T{approx} 56000 K at a pressure of P {approx} 265 GPa) are attained. The density, pressure, temperature, and electrical conductivity of the nonideal plasma of shock-compressed liquid nitrogen are measured. A nearly isochoric behavior of the nitrogen shock adiabat is observed in the pressure range P = 100-300 GPa. The thermodynamics of shock-compressed nitrogen is an alyzed using the model of the equation of state in the quasi-chemical representation (SAHA code) as well as the semiempirical wide-range equation of state developed at the Institute of Experimental Physics. Experimental results are interpreted on the basis of calculations as the fixation of the boundary of transition of shock-compressed nitrogen from the polymer phase to the state of a strongly nonideal plasma at P {approx} 100 GPa, {approx} 3.4 g/cm{sup 3}.

  17. A temperature-induced narrow DNA curvature range sustains the maximum activity of a bacterial promoter in vitro.

    PubMed

    Prosseda, Gianni; Mazzola, Alessia; Di Martino, Maria Letizia; Tielker, Denis; Micheli, Gioacchino; Colonna, Bianca

    2010-04-01

    Among the molecular strategies bacteria have set up to quickly match their transcriptional program to new environments, changes in sequence-mediated DNA curvature play a crucial role. Bacterial promoters, especially those of mesophilic bacteria, are in general preceded by a curved region. The marked thermosensitivity of curved DNA stretches allows bacteria to rapidly sense outer temperature variations and affects transcription by favoring the binding of activators or repressors. Curved DNA is also able to influence the transcriptional activity of a bacterial promoter directly, without the involvement of trans-acting regulators. This study attempts to quantitatively analyze the role of DNA curvature in thermoregulated gene expression using a real-time in vitro transcription model system based on a specific fluorescence molecular beacon. By analyzing the temperature-dependent expression of a reporter gene in a construct carrying a progressively decreasing bent sequence upstream from the promoter, we show that with a decrease in temperature a narrow curvature range accounts for a significant enhancement of promoter activity. This strengthens the view that DNA curvature-mediated regulation of gene expression is likely a strategy offering fine-tuning control possibilities and that, considering the widespread presence of curved sequences upstream from bacterial promoters, it may represent one of the most primitive forms of gene regulation.

  18. Electrical conductivity and pyroelectricity of lithium-potassium sulphate single crystal in the temperature range 300-950 K

    NASA Astrophysics Data System (ADS)

    Abu El-Fadl, A.; Gaffar, M. A.; Omar, M. H.

    1999-09-01

    The DC electrical conductivity ( σ) along the a- and c-axes and the pyroelectric coefficient ( p) along the pyroelectric c-axis of lithium-potassium sulphate (LKS) single crystal are measured in the temperature range 300-950 K. The measurements of σ show anomalous behaviour at the transition point around 705 K. The σ- T relationship reveals an activation energy of conduction along the c-axis of 0.85 eV above and 0.37 eV below the transition temperature, respectively. The effect of thermal recycling on the electric conduction is discussed. A maximum signal at about 720 K and a variation in the sign of p at about 704 K have been observed. The phase transition reported in the literature at 333 K was not confirmed by our measurements. The current density ( J) is measured as a function of the applied electric field ( E) below and above the phase transition temperature along the c- and a-axes in order to estimate the type of conduction dominated and the effect of E upon the conductivity measurements of this crystal.

  19. Standard molar Gibbs free energy of formation of PbO(s) over a wide temperature range from EMF measurements

    NASA Astrophysics Data System (ADS)

    Ganesan, Rajesh; Gnanasekaran, T.; Srinivasa, Raman S.

    2003-08-01

    The EMF of the following galvanic cells, Kanthal, Re, Pb, PbO∣ CSZ∣ O2 (1 atm.), PtKanthal, Re, Pb, PbO∣ CSZ∣ O2(1 atm.), RuO2, Ptwere measured as a function of temperature. With O 2 (1 atm.), RuO 2 as the reference electrode, measurements were possible at low temperatures close to the melting point of Pb. Standard Gibbs energy of formation, Δ fG0m<β-PbO> was calculated from the emf measurements made over a wide range of temperature (612-1111 K) and is given by the expression: ΔfG 0m< β-PbO>±0.10 kJ=-218.98+0.09963T . A third law treatment of the data yielded a value of -218.08 ± 0.07 kJ mol -1 for the enthalpy of formation of PbO(s) at 298.15 K, Δ fH0m<β-PbO> which is in excellent agreement with second law estimate of -218.07 ± 0.07 kJ mol -1.

  20. Winter body temperature patterns in free-ranging Cape ground squirrel, Xerus inauris: no evidence for torpor.

    PubMed

    Wilson, Wendy A; O'Riain, M Justin; Hetem, Robyn S; Fuller, Andrea; Fick, Linda G

    2010-10-01

    The body temperature (T(b)) of Cape ground squirrels (Xerus inauris, Sciuridae) living in their natural environment during winter has not yet been investigated. In this study we measured abdominal T(b) of eight free-ranging Cape ground squirrels over 27 consecutive days during the austral winter. Mean daily T(b) was relatively stable at 37.0 ± 0.2°C (range 33.4 to 40.2°C) despite a marked variation in globe temperature (T(g)) (range -7 to 37°C). Lactating females (n = 2) consistently had a significantly higher mean T (b) (0.7°C) than non-lactating females (n = 3) and males. There was a pronounced nychthemeral rhythm with a mean active phase T(b) of 38.1 ± 0.1°C and a mean inactive phase T(b) of 36.3 ± 0.3°C for non-lactating individuals. Mean daily amplitude of T(b) rhythm was 3.8 ± 0.2°C. T(b) during the active phase closely followed T(g) and mean active phase T(b) was significantly correlated with mean active phase T(g) (r(2) = 0.3-0.9; P < 0.01). There was no evidence for daily torpor or pronounced hypothermia during the inactive phase, and mean minimum inactive phase T(b) was 35.7 ± 0.3°C for non-lactating individuals. Several alternatives (including nocturnal huddling, an aseasonal breeding pattern and abundant winter food resources) as to why Cape ground squirrels do not employ nocturnal hypothermia are discussed.

  1. The investigation of the electrical properties of Fe3O4/n-Si heterojunctions in a wide temperature range.

    PubMed

    Deniz, Ali Rıza; Çaldıran, Zakir; Metin, Önder; Meral, Kadem; Aydoğan, Şakir

    2016-07-01

    Monodisperse 8nm Fe3O4 nanoparticles (NPs) were synthesized by the thermal decomposition of iron(III) acetylacetonate in oleylamine and then were deposited onto n-type silicon wafer having the Al ohmic contact. Next, the morphology of the Fe3O4 NPs were characterized by using TEM and XRD. The optical properties of Fe3O4 NPs film was studied by UV-Vis spectroscopoy and its band gap was calculated to be 2.16eV. Au circle contacts with 7.85×10(-3)cm(2) area were provided on the Fe3O4 film via evaporation at 10(-5)Torr and the Au/Fe3O4 NPs/n-Si/Al heterojunction device were fabricated. The temperature-dependent junction parameters of Au/Fe3O4/n-Si/Al device including ideality factor, barrier height and series resistance were calculated by using the I-V characteristics in a wide temperature range of 40-300K. The results revealed that the ideality factor and series resistance increased by the decreasing temperature while the barrier height decreases. The Richardson constant of Au/Fe3O4/n-Si/Al device was calculated to be 2.17A/K(2)cm(2) from the I-V characteristics. The temperature dependence of Au/Fe3O4/n-Si/Al heterojunction device showed a double Gaussian distribution, which is caused by the inhomogeneities characteristics of Fe3O4/n-Si heterojunction.

  2. SNCR De-NOx within a moderate temperature range using urea-spiked hydrazine hydrate as reductant.

    PubMed

    Chen, H; Chen, D Z; Fan, S; Hong, L; Wang, D

    2016-10-01

    In this research, urea-spiked hydrazine hydrate solutions are used as reductants for the Selective Non-Catalytic Reduction (SNCR) De-NOx process below 650 °C. The urea concentration in the urea/hydrazine hydrate solutions is chosen through experimental and theoretical studies. To determine the mechanism of the De-NOx process, thermogravimetric analysis (TGA) of the urea/hydrazine hydrate solutions and their thermal decomposition in air and nitrogen atmospheres were studied to understand their decomposition behaviours and redox characteristics. Then a plug flow reactor (PFR) model was adopted to simulate the De-NOx processes in a pilot scale tubular reactor, and the calculated De-NOx efficiency vs. temperature profiles were compared with experimental results to support the mechanism and choose the proper reductant and its reaction temperature. Both the experimental and calculated results show that when the urea is spiked into hydrazine hydrate solution to make the urea-N content approximately 16.7%-25% of the total N content in the solution, better De-NOx efficiencies can be obtained in the temperature range of 550-650 °C, under which NH3 is inactive in reducing NOx. And it is also proved that for these urea-spiked hydrazine hydrate solutions, the hydrazine decomposition through the pathway N2H4 + M = N2H3 + H + M is enhanced to provide radical H, which is active to reduce NO. Finally, the reaction routes for SNCR De-NOx process based on urea-spiked hydrazine hydrate at the proper temperature are proposed.

  3. SNCR De-NOx within a moderate temperature range using urea-spiked hydrazine hydrate as reductant.

    PubMed

    Chen, H; Chen, D Z; Fan, S; Hong, L; Wang, D

    2016-10-01

    In this research, urea-spiked hydrazine hydrate solutions are used as reductants for the Selective Non-Catalytic Reduction (SNCR) De-NOx process below 650 °C. The urea concentration in the urea/hydrazine hydrate solutions is chosen through experimental and theoretical studies. To determine the mechanism of the De-NOx process, thermogravimetric analysis (TGA) of the urea/hydrazine hydrate solutions and their thermal decomposition in air and nitrogen atmospheres were studied to understand their decomposition behaviours and redox characteristics. Then a plug flow reactor (PFR) model was adopted to simulate the De-NOx processes in a pilot scale tubular reactor, and the calculated De-NOx efficiency vs. temperature profiles were compared with experimental results to support the mechanism and choose the proper reductant and its reaction temperature. Both the experimental and calculated results show that when the urea is spiked into hydrazine hydrate solution to make the urea-N content approximately 16.7%-25% of the total N content in the solution, better De-NOx efficiencies can be obtained in the temperature range of 550-650 °C, under which NH3 is inactive in reducing NOx. And it is also proved that for these urea-spiked hydrazine hydrate solutions, the hydrazine decomposition through the pathway N2H4 + M = N2H3 + H + M is enhanced to provide radical H, which is active to reduce NO. Finally, the reaction routes for SNCR De-NOx process based on urea-spiked hydrazine hydrate at the proper temperature are proposed. PMID:27427778

  4. Impact of Solar Control PVB Glass on Vehicle Interior Temperatures, Air-Conditioning Capacity, Fuel Consumption, and Vehicle Range

    SciTech Connect

    Rugh, J.; Chaney, L.; Venson, T.; Ramroth, L.; Rose, M.

    2013-04-01

    The objective of the study was to assess the impact of Saflex1 S-series Solar Control PVB (polyvinyl butyral) configurations on conventional vehicle fuel economy and electric vehicle (EV) range. The approach included outdoor vehicle thermal soak testing, RadTherm cool-down analysis, and vehicle simulations. Thermal soak tests were conducted at the National Renewable Energy Laboratory's Vehicle Testing and Integration Facility in Golden, Colorado. The test results quantified interior temperature reductions and were used to generate initial conditions for the RadTherm cool-down analysis. The RadTherm model determined the potential reduction in air-conditioning (A/C) capacity, which was used to calculate the A/C load for the vehicle simulations. The vehicle simulation tool identified the potential reduction in fuel consumption or improvement in EV range between a baseline and modified configurations for the city and highway drive cycles. The thermal analysis determined a potential 4.0% reduction in A/C power for the Saflex Solar PVB solar control configuration. The reduction in A/C power improved the vehicle range of EVs and fuel economy of conventional vehicles and plug-in hybrid electric vehicles.

  5. A long-range and long-life telemetry data-acquisition system for heart rate and multiple body temperatures from free-ranging animals

    NASA Technical Reports Server (NTRS)

    Lund, G. F.; Westbrook, R. M.; Fryer, T. B.; Miranda, R. F.

    1979-01-01

    The system includes an implantable transmitter, external receiver-retransmitter collar, and a microprocessor-controlled demodulator. The size of the implant is suitable for animals with body weights of a few kilograms or more; further size reduction of the implant is possible. The ECG is sensed by electrodes designed for internal telemetry and to reduce movement artifacts. The R-wave characteristics are then specifically selected to trigger a short radio frequency pulse. Temperatures are sensed at desired locations by thermistors and then, based on a heartbeat counter, transmitted intermittently via pulse interval modulation. This modulation scheme includes first and last calibration intervals for a reference by ratios with the temperature intervals to achieve good accuracy even over long periods. Pulse duration and pulse sequencing are used to discriminate between heart rate and temperature pulses as well as RF interference.

  6. Plasticity and constraints on fatty acid composition in the phospholipids and triacylglycerols of Arabidopsis accessions grown at different temperatures

    PubMed Central

    2013-01-01

    Background Natural selection acts on multiple traits in an organism, and the final outcome of adaptive evolution may be constrained by the interaction of physiological and functional integration of those traits. Fatty acid composition is an important determinant of seed oil quality. In plants the relative proportions of unsaturated fatty acids in phospholipids and seed triacylglycerols often increases adaptively in response to lower growing temperatures to increase fitness. Previous work produced evidence of genetic constraints between phospholipids and triacylglycerols in the widely studied Arabidopsis lines Col and Ler, but because these lines are highly inbred, the correlations might be spurious. In this study, we grew 84 wild Arabidopsis accessions at two temperatures to show that genetic correlation between the fatty acids of the two lipid types is not expected and one should not influence the other and seed oil evolution and also tested for the adaptive response of fatty acids to latitude and temperature. Results As expected no significant correlations between the two lipids classes at either growing temperature were observed. The saturated fatty acids and erucic acid of triacylglycerols followed a significant latitudinal cline, while the fatty acids in phospholipids did not respond to latitude as expected. The expected plastic response to temperature was observed for all the triacylglycerol fatty acids whereas only oleic acid showed the expected pattern in phospholipids. Considerable phenotypic variation of the fatty acids in both the lipid types was seen. Conclusion We report the first evidence supporting adaptive evolution of seed triacylglycerols in Arabidopsis on a latitudinal cline as seen in other species and also their plastic adaptive response to growing temperature. We show that as expected there is no genetic correlations between the fatty acids in triacylglycerols and phospholipids, indicating selection can act on seed triacylglycerols without

  7. Kinetics of the ClO + HO2 reaction over the temperature range T = 210-298 K.

    PubMed

    Ward, Michael K M; Rowley, David M

    2016-02-17

    The rate coefficient for the atmospherically important radical reaction: which leads to ozone depletion, has been studied over the temperature range T = 210-298 K and at ambient pressure p = 760 ± 20 Torr. The reaction was studied using laser flash photolysis radical generation coupled with broadband charge coupled device absorption spectroscopy employing a two-dimensional charge-coupled-device (CCD) detection system. ClO radicals were generated following the photolysis of Cl2 and Cl2O gas mixtures diluted in nitrogen and oxygen. ClO radicals were monitored using broadband fingerprinting of their characteristic vibronic (A(2)Π ← X(2)Π) spectral structure, representing a definitive monitoring of this radical. Addition of hydroperoxy radical precursors to the gas mixture (methanol and oxygen) subsequently led to a competition for photolytically generated Cl atoms and a simultaneous prompt formation of both ClO and HO2 radicals. Detailed analysis and modelling of the radical production routes provided a degree of constraint into numerical integration simulations which were then used to interrogate and fit to ClO temporal profiles to extract the rate coefficient k1. The ambient temperature (T = 298 K) rate coefficient reported is k1 = (8.5 ± 1.5) × 10(-12) cm(3) molecule(-1) s(-1). The rate coefficient, k1, is described by the Arrhenius expression:where errors are 1σ statistical only. This significant rate coefficient is greater than previously reported, with a stronger negative temperature dependence than previously observed. Consequently this suggests that the contribution of to ozone loss, in particular at mid-latitudes might be currently underestimated in models. This work reports atmospheric pressure kinetic parameters for this reaction which are greater than those reported from low pressure studies, perhaps supporting ClO and HO2 association as predicted by previous theoretical studies of this process and highlighting the need for further pressure

  8. Specific heat and thermodynamic characteristics of the system Bi-Sr-Ca-Mg-Cu-O in the temperature range 4.2 300 K

    NASA Astrophysics Data System (ADS)

    Gololobov, E. M.; Novysh, B. V.; Prytkova, N. A.; Tomilo, Zh. M.; Shimanskaya, N. M.; Abeliov, Ya. A.; Maiornikova, G. V.; Yagina, A. B.

    1991-06-01

    Results are presented from an experimental study of specific heat of the superconductive metal oxide system Bi -Sr-Ca-Mg-Cu-O over the temperature range 4.2 300 K. Temperature-dependent components of entropy and enthalpy are calculated. A correlation is made between Tc and standard entropy and enthalpy values for high temperature superconductors of various classes.

  9. Viscosity of liquid lithium by an oscillating-cup viscometer in the temperature range 464-923 K

    SciTech Connect

    Ito, Y.; Minami, K.; Nagashima, A.

    1989-01-01

    The liquid lithium has been proposed as a blanket substance of D-T fusion reactor. Among the previously published viscosity data of liquid lithium by different authors, a sizable discrepancy is observed. In the present study, the viscosity of liquid lithium was measured by an oscillating-cup viscometer in the temperature range from 464 to 923 K. It was concluded that the disagreement among the previous studies was owing to the difference theory used for calculating the viscosity and also to the influence of the corrosion of the container wall. It was shown that recalculation of values in previous studies with the aid of Kestin-Newell equation, the equation used in the present study, would show reasonable agreement with the present results. The accuracy of the present measurements was estimated as /plus minus/3%.

  10. Evaluation of a Programmable Voltage-Controlled MEMS Oscillator, Type SiT3701, Over a Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2009-01-01

    Semiconductor chips based on MEMS (Micro-Electro-Mechanical Systems) technology, such as sensors, transducers, and actuators, are becoming widely used in today s electronics due to their high performance, low power consumption, tolerance to shock and vibration, and immunity to electro-static discharge. In addition, the MEMS fabrication process allows for the miniaturization of individual chips as well as the integration of various electronic circuits into one module, such as system-on-a-chip. These measures would simplify overall system design, reduce parts count and interface, improve reliability, and reduce cost; and they would meet requirements of systems destined for use in space exploration missions. In this work, the performance of a recently-developed MEMS voltage-controlled oscillator was evaluated under a wide temperature range. Operation of this new commercial-off-the-shelf (COTS) device was also assessed under thermal cycling to address some operational conditions of the space environment

  11. Absolute rate of the reaction of O/3-P/ with hydrogen sulfide over the temperature range 263 to 495 K

    NASA Technical Reports Server (NTRS)

    Whytock, D. A.; Timmons, R. B.; Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

    1976-01-01

    The technique of flash photolysis coupled with time resolved detection of O via resonance fluorescence has been used to obtain rate constants for the reaction of O(3-P) with H2S at temperatures from 263 to 495 K and at pressures in the range 10-400 torr. Under conditions where secondary reactions are avoided, the measured rate constants for the primary step obey the Arrhenius equation k = (7.24 plus or minus 1.07) x 10 to the -12th exp(-3300 plus or minus 100/1.987 T) cu cm/molecules/s. Experiments with D2S show that the reaction exhibits a primary isotope effect, in support of a hydrogen abstraction mechanism.

  12. Metallographic anlaysis and strength investigation of different Be-Cu joints in the temperature range RT-3500C

    SciTech Connect

    Gervash, A.A.; Giniatouline, R.N.; Mazul, I.V.

    1995-09-01

    The goal of this work is to estimate the strength and structure of different Be-Cu joining techniques. Brazing, diffusion bonding and joint rolling methods were chosen as ITER Be-Cu joint method candidates. Selected for ITER application Be-Cu joints were produced as technological plates (30-50 mm x 50-100 mm x thickness). AR samples for farther investigations were cutted out from initial technological plates. To compare mechanical strength of selected Be-Cu joints tensile and shearing tests of chosen candidates were carried out in the temperature range RT - 350{degrees}C. The metallographic analysis of Be-Cu crosssection was also done. Preliminary results of these tests as well as metallographic analysis data are presented. The industrial possibilities of producing required for ITER full scale Be-Cu joints are discussed.

  13. Free range rearing of pigs with access to pasture grazing - effect on fatty acid composition and lipid oxidation products.

    PubMed

    Nilzén, V; Babol, J; Dutta, P C; Lundeheim, N; Enfält, A C; Lundström, K

    2001-07-01

    The influence of free-range rearing, RN genotype and sex on different pig meat quality traits, including intramuscular fatty acid composition and levels of lipid oxidation products, were studied. A total of 60 Hampshire crossbred pigs were reared outdoors for two months with access to green feed, while 60 others were kept indoors, in a 120-m(2)-large pen, throughout the rearing period. From these 120 animals a subsample of 44 animals was chosen for meat quality analysis. Of the three factors studied, the RN genotype had the largest influence on basic technological meat quality traits, whereas the rearing conditions and sex had limited effects. However, outdoor rearing resulted in higher levels of polyunsaturated fatty acids in the intramuscular fat (P=0.026) and in an increased level of vitamin E (P=0.030) compared with the pigs that had been reared indoors. The sex and RN genotype of the animals also had an effect on the fatty acid profile: females had higher levels of unsaturated fatty acids (P=0.003) as well as lower levels of saturated fatty acids (P=0.011) than castrated males. Carriers of the RN(-) allele expressed a higher sum of omega-3 fatty acids (P=0.047) and C22:5 (P=0.012) than did the non-carriers. In a storage study where meat from free-range and indoor reared pigs was stored for 3 months at-20°C, it was shown that the lipid oxidation product malondialdehyde was formed at increased levels in animals that had a higher lean meat percentage than others, i.e. females that were carriers of the RN(-) gene and that were reared outdoors. PMID:22062255

  14. Impact of vegetation removal and soil aridation on diurnal temperature range in a semiarid region: application to the Sahel.

    PubMed

    Zhou, Liming; Dickinson, Robert E; Tian, Yuhong; Vose, Russell S; Dai, Yongjiu

    2007-11-13

    Increased clouds and precipitation normally decrease the diurnal temperature range (DTR) and thus have commonly been offered as explanation for the trend of reduced DTR observed for many land areas over the last several decades. Observations show, however, that the DTR was reduced most in dry regions and especially in the West African Sahel during a period of unprecedented drought. Furthermore, the negative trend of DTR in the Sahel appears to have stopped and may have reversed after the rainfall began to recover. This study develops a hypothesis with climate model sensitivity studies showing that either a reduction in vegetation cover or a reduction in soil emissivity would reduce the DTR by increasing nighttime temperature through increased soil heating and reduced outgoing longwave radiation. Consistent with empirical analyses of observational data, our results suggest that vegetation removal and soil aridation would act to reduce the DTR during periods of drought and human mismanagement over semiarid regions such as the Sahel and to increase the DTR with more rainfall and better human management. Other mechanisms with similar effects on surface energy balance, such as increased nighttime downward longwave radiation due to increased greenhouse gases, aerosols, and clouds, would also be expected to have a larger impact on DTR over drier regions.

  15. Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 to 1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.; Whittenberger, J. Daniel

    1987-01-01

    Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

  16. Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 - 1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.; Whittenberger, J. Daniel

    1987-01-01

    Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

  17. State of water in starch-water systems in the gelatinization temperature range as investigated using dielectric relaxation spectroscopy

    NASA Astrophysics Data System (ADS)

    Motwani, Tanuj

    Starch-water interactions occurring during gelatinization are critical for developing a mechanistic understanding of the gelatinization process. The overall goal of this project was to investigate the state of water in starch-water systems in the gelatinization temperature range using dielectric relaxation spectroscopy. In the first part of the project, the dielectric response of native wheat starch-water slurries was measured at seven different starch concentrations between 5--60% starch (w/w) in the frequency range of 200 MHz--20 GHz at 25°C. The deconvolution of the dielectric spectra using the Debye model revealed presence of up to three relaxation processes. The relaxation time range of what were considered to be the high, intermediate and low frequency relaxations were 4--9 ps, 20--25 ps and 230--620 ps, respectively. The high frequency relaxation was observed at all starch concentrations, while the intermediate and low frequency relaxation were only observed at starch concentrations of 10% and above, and 30% and above, respectively. The high frequency relaxation was attributed to bulk water, while the intermediate and low frequency relaxations were attributed to rotationally restrained water molecules present in the starch-water system. To investigate the state of water in the gelatinization temperature range, the dielectric response, gelatinization enthalpy and water absorption by 10%, 30% or 50% starch slurries were measured after heating the slurries to different end temperatures between 40--90°C for 30 min. The high frequency relaxation time for 10% starch slurry dropped significantly (P<0.001) upon heating up to 60°C. For 30% and 50% starch slurries, high frequency relaxation times were not significantly influenced (P>0.159) by heating up to 80°C. The intermediate and low frequency relaxation times were not significantly influenced (P>0.712) by heating for all starch concentrations. Also, the amount of water associated with the three relaxations was

  18. A technique for extending the precision and the range of temperature programmed desorption toward extremely low coverages

    NASA Astrophysics Data System (ADS)

    Haegel, Stefan; Zecho, Thomas; Wehner, Stefan

    2010-03-01

    In this paper, an improvement of the temperature programmed desorption (TPD) technique is introduced, which facilitates fully automated sampling of TPD spectra with excellent reproducibility, especially useful for extremely low coverages. By averaging many sampled TPD spectra, the range of the TPD technique can be extended toward lower coverages, as well as the quality of the spectra can be improved. This allows for easy extraction of information about the adsorbate-surface bond. A state of the art TPD apparatus with a two chamber setup and a high quality quadrupole mass spectrometer was extended by automated components. These are an automated gas dosing system, ensuring precise dosing of gas, combined with a motor driven sample manipulation unit and a liquid nitrogen cryostat with automatic refilling. In addition all components were controlled by a computer. A large number of TPD cycles could be sampled without the need of interaction of an operator. Here, it is shown for up to more than 400 TPD cycles. This opens a wide range of new interesting applications for the TPD technique, especially in the limit of zero coverage. Here, basic experiments on well known adsorbate systems are shown to view the ability and limit of this approach.

  19. Pressure-temperature history of the Brooks Range and Seward Peninsula, Alaska HP-LT units and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Lemonnier, N.; Labrousse, L.; Agard, P.; Till, A. B.

    2013-12-01

    Metamorphic rocks in the inner zones of mountain belts constitute a marker of vertical movements within orogenic wedges, themselves controled by balance between boundary conditions and volume forces. They provide key evidence for paleogeographic and tectonic reconstruction of convergence zones. In the Arctic, the Amerasian basin opened in cretaceous time and evolved in the upper plate of the Pacific subduction system. The tectonic evolution of the Brooks Range, northern Alaska, is a key issue for understanding possible coupling between these two dynamics. HP-LT metamorphic rocks, now exposed in the Schist belt, Brooks Range, and the Nome Complex, Seward Peninsula, were brought to the surface during Early Cretaceous to Paleocene time. The processes responsible for their exhumation (syn-collisional nappe-stacking or post-collisional extensional detachment) are still a matter of debate, and have direct implications in terms of orogenic boundary conditions and coupling between subduction processes (to the south) and basin response (to the north; the North Slope). Systematic thermometry via Raman Spectrometry (RSCM) on carbonaceous material from regional transects in the Schist Belt and the Seward Peninsula as well as pseudosections calculations allow the determination of units with contrasting pressure-temperature histories and a comparison of thermal evolution of the two areas. Geodynamic implications of their exhumation is then discussed.

  20. Effect of Gd polarization on the large magnetocaloric effect of GdCrO4 in a broad temperature range

    NASA Astrophysics Data System (ADS)

    Palacios, E.; Tomasi, C.; Sáez-Puche, R.; Dos santos-García, A. J.; Fernández-Martínez, F.; Burriel, R.

    2016-02-01

    The ferromagnetic zircon-type phase of GdCrO4 presents high values for the magnetocaloric (MC) parameters. This compound has large isothermal entropy changes Δ ST under the magnetic field action in a wide temperature range, from 5 to 35 K, reaching a maximum |Δ ST|=29.0 ±0.1 J /kg K at 22 K, for a field increment Δ B =9 T. It orders ferromagnetically at TC=21.3 K via the Cr-Cr exchange interaction and shows a second transition at 4.8 K due to the ordering of the Gd sublattice. The large MC effect is enhanced by the polarization of the Gd3 + ions by the Cr5 + ones via a weaker Gd-Cr interaction. This effect is an interesting feature to be considered in the search for new compounds with a high MC effect in the range of liquid hydrogen or natural gas, regarding the liquefaction of gases by magnetization-demagnetization cycles. This paper contains experimental measurements of magnetization, heat capacity, and direct determinations of the MC effect. The magnetic contribution to the heat capacity Cm has been obtained after subtracting the lattice component. Approximate values for the exchange constants J1 (Cr-Cr) and J3 (Gd-Cr) have been deduced from Cm.

  1. Identification of Stable Processing Parameters in Ti-6Al-4V Alloy from a Wide Temperature Range Across β Transus and a Large Strain Rate Range

    NASA Astrophysics Data System (ADS)

    Quan, Guo-Zheng; Wen, Hai-Rong; Pu, Shi-Ao; Zou, Zhen-Yu; Wu, Dong-Sen

    2015-11-01

    The hot workability of Ti-6Al-4V alloy was investigated according to the measured stress-strain data and their derived forms from a series of hot compressions at the temperatures of 1,023-1,323 K and strain rates of 0.01-10 s-1 with a height reduction of 60%. As the true strain was 0.3, 0.5, 0.7 and 0.9, respectively, the response maps of strain rate sensitivity (m-value), power dissipation efficiency (η-value) and instability parameter (ξ-value) to temperature and strain rate were developed on the basis of dynamic material model (DMM). Then the processing map was obtained by superimposition of the power dissipation and the instability maps. According to the processing map, the stable regions (η > 0 and ξ > 0) and unstable regions (η < 0 or ξ < 0) were clarified clearly. Further, the stable regions (temperatures of 1,198-1,248 K and strain rates of 0.01-0.1 s-1) with higher η value (> 0.3) corresponding to the ideal deformation mechanisms involving globularization and superplasticity were identified and recommended. The microstructures of the deformed samples were then observed by microscopy. And homogeneous microstructures with refined grains were found in the recommended parameter domains. The optimal working parameter domains identified by processing map and validated by microstructure observations contribute to the design in reasonable hot forming process of Ti-6Al-4V alloy without resorting to expensive and time-consuming trial-and-error methods.

  2. Stress-induced rise in body temperature is repeatable in free-ranging Eastern chipmunks (Tamias striatus).

    PubMed

    Careau, Vincent; Réale, Denis; Garant, Dany; Speakman, John R; Humphries, Murray M

    2012-04-01

    In response to handling or other acute stressors, most mammals, including humans, experience a temporary rise in body temperature (T(b)). Although this stress-induced rise in T(b) has been extensively studied on model organisms under controlled environments, individual variation in this interesting phenomenon has not been examined in the field. We investigated the stress-induced rise in T(b) in free-ranging eastern chipmunks (Tamias striatus) to determine first if it is repeatable. We predicted that the stress-induced rise in T(b) should be positively correlated to factors affecting heat production and heat dissipation, including ambient temperature (T(a)), body mass (M(b)), and field metabolic rate (FMR). Over two summers, we recorded both T(b) within the first minute of handling time (T(b1)) and after 5 min of handling time (T(b5)) 294 times on 140 individuals. The mean ∆T(b) (T(b5) - T(b1)) during this short interval was 0.30 ± 0.02°C, confirming that the stress-induced rise in T(b) occurs in chipmunks. Consistent differences among individuals accounted for 40% of the total variation in ∆T(b) (i.e. the stress-induced rise in T(b) is significantly repeatable). We also found that the stress-induced rise in T(b) was positively correlated to T(a), M(b), and mass-adjusted FMR. These results confirm that individuals consistently differ in their expression of the stress-induced rise in T(b) and that the extent of its expression is affected by factors related to heat production and dissipation. We highlight some research constraints and opportunities related to the integration of this laboratory paradigm into physiological and evolutionary ecology. PMID:22076533

  3. The long-term trend in the diurnal temperature range over Asia and its natural and anthropogenic causes

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Li, Zhanqing; Yang, Xin; Gong, Hainan; Li, Chao; Xiong, Anyuan

    2016-04-01

    Understanding the causes of long-term temperature trends is at the core of climate change studies. Any observed trend can result from natural variability or anthropogenic influences or both. In the present study, we evaluated the performance of 18 climate models from the Coupled Model Intercomparison Project Phase 5 on simulating the Asian diurnal temperature range (DTR) and explored the potential causes of the long-term trend in the DTR by examining the response of the DTR to natural forcing (volcanic aerosols and solar variability) and anthropogenic forcing (anthropogenic greenhouse gases (GHG) and aerosols) in the historical period of 1961-2005. For the climatology, the multimodel ensemble mean reproduced the geographical distribution and amplitude of the DTR over eastern China and India but underestimated the magnitudes of the DTR over the Tibetan Plateau and the high-latitude regions of the Asian continent. These negative biases in the DTR over frigid zones existed in most models. Seasonal biases in the DTR pattern from models were similar to the bias in the annual mean DTR pattern. Based on three selected state-of-the-art models, the observed decreasing trend in the DTR over Asia was reasonably reproduced in the all-forcing run. A comparison of separate forcing experiments revealed that anthropogenic forcing plays the dominant role in the declining trend in the DTR. Observations and model simulations showed that GHG forcing is mainly responsible for the negative trends in the DTR over Asia but that anthropogenic aerosol forcing was also behind the decreasing trend in the DTR over China and especially over eastern China.

  4. Bilateral Comparison Between NIM and NMC Over the Temperature Range from 83.8058 K to 692.677 K

    NASA Astrophysics Data System (ADS)

    Sun, Jianping; Ye, Shaochun; Kho, Haoyuan; Zhang, Jintao; Wang, Li

    2015-08-01

    A bilateral comparison of local realization of the International Temperature Scale of 1990 between the National Institute of Metrology (NIM) and National Metrology Centre (NMC) was carried out over the temperature range from 83.8058 K to 692.677 K. It involved six fixed points including the argon triple point, the mercury triple point, the triple point of water, the melting point of gallium, the freezing point of tin, and the freezing point of zinc. In 2009, NMC asked NIM to participate in a bilateral comparison to link the NMC results to the Consultative Committee for Thermometry Key Comparison 3 (CCT-K3) and facilitate the NMC's calibration and measurement capabilities submission. This comparison was agreed by NIM and Asia Pacific Metrology Programme in 2009, and registered in the Key Comparison Database in 2010 as CCT-K3.2. NMC supplied two fused silica sheath standard platinum resistance thermometers (SPRTs) as traveling standards. One of them was used at the Ga, Sn, and Zn fixed points, while the other one was used at the Ar and Hg fixed points. NMC measured them before and after NIM measured them. During the comparison, a criterion for the SPRT was set as the stability at the triple point of water to be less than 0.3 mK. The results for both laboratories are summarized. A proposal for linking the NMC's comparison results to CCT-K3 is presented. The difference between NMC and NIM and the difference between NMC and the CCT-K3 average reference value using NIM as a link are reported with expanded uncertainties at each measured fixed point.

  5. Big Data, Small Data: Accessing and Manipulating Geoscience Data Ranging From Repositories to Student-Collected Data Sets Using GeoMapApp

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.

    2015-12-01

    We often demand information and data to be accessible over the web at no cost, and no longer do we expect to spend time labouriously compiling data from myriad sources with frustratingly-different formats. Instead, we increasingly expect convenience and consolidation. Recent advances in web-enabled technologies and cyberinfrastructure are answering those calls by providing data tools and resources that can transform undergraduate education. By freeing up valuable classroom time, students can focus upon gaining deeper insights and understanding from real-world data. GeoMapApp (http://www.geomapapp.org) is a map-based data discovery and visualisation tool developed at Lamont-Doherty Earth Observatory. GeoMapApp promotes U-Learning by working across all major computer platforms and functioning anywhere with internet connectivity, by lowering socio-economic barriers (it is free), by seamlessly integrating thousands of built-in research-grade data sets under intuitive menus, and by being adaptable to a range of learning environments - from lab sessions, group projects, and homework assignments to in-class pop-ups. GeoMapApp caters to casual and specialist users alike. Contours, artificial illumination, 3-D displays, data point manipulations, cross-sectional profiles, and other display techniques help students better grasp the content and geospatial context of data. Layering capabilities allow easy data set comparisons. The core functionality also applies to imported data sets: Student-collected data can thus be imported and analysed using the same techniques. A new Save Session function allows educators to preserve a pre-loaded state of GeoMapApp. When shared with a class, the saved file allows every student to open GeoMapApp at exactly the same starting point from which to begin their data explorations. Examples of built-in data sets include seafloor crustal age, earthquake locations and focal mechanisms, analytical geochemistry, ocean water physical properties, US and

  6. Development of Superior Sorbents for Separation of CO2 from Flue Gas at a Wide Temperature Range During Coal Combustion

    SciTech Connect

    Panagiotis G. Smirniotis

    2007-06-30

    In chapter 1, the studies focused on the development of novel sorbents for reducing the carbon dioxide emissions at high temperatures. Our studies focused on cesium doped CaO sorbents with respect to other major flue gas compounds in a wide temperature range. The thermo-gravimetric analysis of sorbents with loadings of CaO doped on 20 wt% cesium demonstrated high CO{sub 2} sorption uptakes (up to 66 wt% CO{sub 2}/sorbent). It is remarkable to note that zero adsorption affinity for N{sub 2}, O{sub 2}, H{sub 2}O and NO at temperatures as high as 600 C was observed. For water vapor and nitrogen oxide we observed a positive effect for CO{sub 2} adsorption. In the presence of steam, the CO{sub 2} adsorption increased to the highest adsorption capacity of 77 wt% CO{sub 2}/sorbent. In the presence of nitrogen oxide, the final CO{sub 2} uptake remained same, but the rate of adsorption was higher at the initial stages (10%) than the case where no nitrogen oxide was fed. In chapter 2, Ca(NO{sub 3}){sub 2} {center_dot} 4H{sub 2}O, CaO, Ca(OH){sub 2}, CaCO{sub 3}, and Ca(CH{sub 3}COO){sub 2} {center_dot} H{sub 2}O were used as precursors for synthesis of CaO sorbents on this work. The sorbents prepared from calcium acetate (CaAc{sub 2}-CaO) resulted in the best uptake characteristics for CO{sub 2}. It possessed higher BET surface area and higher pore volume than the other sorbents. According to SEM images, this sorbent shows 'fluffy' structure, which probably contributes to its high surface area and pore volume. When temperatures were between 550 and 800 C, this sorbent could be carbonated almost completely. Moreover, the carbonation progressed dominantly at the initial short period. Under numerous adsorption-desorption cycles, the CaAc{sub 2}-CaO demonstrated the best reversibility, even under the existence of 10 vol % water vapor. In a 27 cyclic running, the sorbent sustained fairly high carbonation conversion of 62%. Pore size distributions indicate that their pore volume

  7. A versatile telemetry system for continuous measurement of heart rate, body temperature and locomotor activity in free-ranging ruminants

    PubMed Central

    Signer, Claudio; Ruf, Thomas; Schober, Franz; Fluch, Gerhard; Paumann, Thomas; Arnold, Walter

    2012-01-01

    Summary 1. Measuring physiological and behavioural parameters in free-ranging animals – and therefore under fully natural conditions – is of general biological concern but difficult to perform. 2. We have developed a minimally invasive telemetry system for ruminants that is capable of measuring heart rate (HR), body temperature (Tb) and locomotor activity (LA). A ruminal transmitter unit was per os placed into the reticulum and therefore located in close proximity to the heart. The unit detected HR by the use of an acceleration sensor and also measured Tb. HR and Tb signals were transmitted via short-distance UHF link to a repeater system located in a collar unit. The collar unit decoded and processed signals received from the ruminal unit, measured LA with two different activity sensors and transmitted pulse interval-modulated VHF signals over distances of up to 10 km. 3. HR data measured with the new device contained noise caused by reticulum contractions and animal movements that triggered the acceleration sensor in the ruminal unit. We have developed a software filter to remove this noise. Hence, the system was only capable of measuring HR in animals that showed little or no activity and in the absence of rumen contractions. Reliability of this ‘stationary HR’ measurement was confirmed with a second independent measurement of HR detected by an electrocardiogram in a domestic sheep (Ovis aries). 4. In addition, we developed an algorithm to correctly classify an animal as ‘active’ or ‘at rest’ during each 3-min interval from the output of the activity sensors. Comparison with direct behavioural observations on free-ranging Alpine ibex (Capra ibex) showed that 87% of intervals were classified correctly. 5. First results from applications of this new technique in free-ranging Alpine ibex underlined its suitability for reliable and long-term monitoring of physiological and behavioural parameters in ruminants under harsh field conditions. With the

  8. Long-range charge order in the low-temperature insulating phase of PrNiO3

    NASA Astrophysics Data System (ADS)

    Medarde, M.; Fernández-Díaz, M. T.; Lacorre, Ph.

    2008-12-01

    We report the observation of a static long-range 2Ni3+→Ni3+δ+Ni3-δ charge redistribution in PrNiO3 below TMI=130K by means of high-resolution powder neutron diffraction. In contrast to previous structural studies, these present data show that the symmetry of the low-temperature insulating phase is not orthorhombic but monoclinic P21/n . The two available Ni sites host contracted and expanded NiO6 octahedra which alternate along the three pseudocubic perovskite axes, suggesting the existence of a Ni3+δ/Ni3-δ charge order similar to that reported for the nickelates with heavier lanthanide ions. The difference between the average Ni-O distances in the two Ni sites at T/TMI=0.08 is 0.052(2)Å , which is almost two times smaller than the value reported for LuNiO3 at T/TMI=0.50 [0.084(4)Å] . This result suggests a progressive decrease in δ by approaching the itinerant limit and gives further support to the charge disproportionation mechanism as an origin of the metal-insulator transition in the whole RNiO3 family.

  9. Higher Storage Temperature Causes Greater Salmonella enterica Serovar Typhimurium Internal Penetration of Artificially Contaminated, Commercially Available, Washed Free Range Eggs.

    PubMed

    Whiley, Alice; Fallowfield, Howard; Ross, Kirstin; McEvoy, Vanessa; Whiley, Harriet

    2016-07-01

    Foodborne salmonellosis is a major public health concern, with contaminated eggs identified as a significant source of infection. In Australia, the most prevalent cause of salmonellosis from eggs is Salmonella enterica subsp. enterica serovar Typhimurium. This study explored the effect of temperature after 1, 7, 14, 21, and 28 days of storage on commercially available washed free range eggs, artificially contaminated with Salmonella Typhimurium on the external surface. At each time point, the external surface of the egg, the crushed eggshell, and the internal egg yolk and albumen were analyzed for Salmonella. After 28 days of storage, 25% of eggs stored at 4°C, 50% of eggs stored at 14°C, and 100% of eggs stored at 23 and 35°C were internally contaminated with Salmonella. After 1 day of storage, more than 50% of all eggs had Salmonella present in the crushed shell after the external surface had been disinfected with ethanol. This is the first study to demonstrate that refrigeration reduced the potential for Salmonella Typhimurium to penetrate the eggshell membrane and internally contaminate table eggs commercially available in Australia. It also suggests that the processes of cracking eggs may be a source of cross-contamination within the kitchen.

  10. Higher Storage Temperature Causes Greater Salmonella enterica Serovar Typhimurium Internal Penetration of Artificially Contaminated, Commercially Available, Washed Free Range Eggs.

    PubMed

    Whiley, Alice; Fallowfield, Howard; Ross, Kirstin; McEvoy, Vanessa; Whiley, Harriet

    2016-07-01

    Foodborne salmonellosis is a major public health concern, with contaminated eggs identified as a significant source of infection. In Australia, the most prevalent cause of salmonellosis from eggs is Salmonella enterica subsp. enterica serovar Typhimurium. This study explored the effect of temperature after 1, 7, 14, 21, and 28 days of storage on commercially available washed free range eggs, artificially contaminated with Salmonella Typhimurium on the external surface. At each time point, the external surface of the egg, the crushed eggshell, and the internal egg yolk and albumen were analyzed for Salmonella. After 28 days of storage, 25% of eggs stored at 4°C, 50% of eggs stored at 14°C, and 100% of eggs stored at 23 and 35°C were internally contaminated with Salmonella. After 1 day of storage, more than 50% of all eggs had Salmonella present in the crushed shell after the external surface had been disinfected with ethanol. This is the first study to demonstrate that refrigeration reduced the potential for Salmonella Typhimurium to penetrate the eggshell membrane and internally contaminate table eggs commercially available in Australia. It also suggests that the processes of cracking eggs may be a source of cross-contamination within the kitchen. PMID:27357046

  11. Fluoride salts as phase change materials for thermal energy storage in the temperature range 1000-1400 K

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1988-01-01

    Eutectic compositions and congruently melting intermediate compounds in binary and ternary fluoride salt systems were characterized for potential use as latent heat of fusion phase change materials to store thermal energy in the temperature range 1000-1400 K. The melting points and eutectic compositions for many systems with published phase diagrams were experimentally verified and new eutectic compositions having melting points between 1000 and 1400 K were identified. Heats of fusion of several binary and ternary eutectics and congruently melting compounds were experimentally measured by differential scanning calorimetry. For a few systems in which heats of mixing in the melts have been measured, heats of fusion of the eutectics were calculated from thermodynamic considerations and good agreement was obtained between the measured and calculated values. Several combinations of salts with high heats of fusion per unit mass (greater than 0.7 kJ/g) have been identified for possible use as phase change materials in advanced solar dynamic space power applications.

  12. Variability and trend of diurnal temperature range in China and their relationship to total cloud cover and sunshine duration

    NASA Astrophysics Data System (ADS)

    Xia, X.

    2013-05-01

    This study aims to investigate the effect of total cloud cover (TCC) and sunshine duration (SSD) in the variation of diurnal temperature range (DTR) in China during 1954-2009. As expected, the inter-annual variation of DTR was mainly determined by TCC. Analysis of trends of 30-year moving windows of DTR and TCC time series showed that TCC changes could account for that of DTR in some cases. However, TCC decreased during 1954-2009, which did not support DTR reduction across China. DTRs under sky conditions such as clear, cloudy and overcast showed nearly the same decreasing rate that completely accounted for the overall DTR reduction. Nevertheless, correlation between SSD and DTR was weak and not significant under clear sky conditions in which aerosol direct radiative effect should be dominant. Furthermore, 30-60% of DTR reduction was associated with DTR decrease under overcast conditions in south China. This implies that aerosol direct radiative effect appears not to be one of the main factors determining long-term changes in DTR in China.

  13. INFLUENCE OF SUMMER STREAM TEMPERATURES ON BLACK SPOT INFESTATION OF JUVENILE COHO SALMON IN THE OREGON COAST RANGE

    EPA Science Inventory

    High summer water temperatures can adversely affect stream salmonids in numerous ways. The direct effects of temperature associated with increased metabolic demand can be exacerbated by other factors, including decreased resistance to disease and increased susceptibility to para...

  14. Increasing the working temperature range of ZrF-BaF-LaF-AlF-NaF glass through microgravity processing

    NASA Astrophysics Data System (ADS)

    Torres, Anthony; Ganley, Jeff; Maji, Arup; Tucker, Dennis; Starodubov, Dmitry

    2014-03-01

    Fluorozirconate glasses, such as ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF), have the potential for optical transmission from 0.3 μm in the ultraviolet to 7 μm in the infrared regions. However, crystallites formed during the fiber-drawing process prevent this glass from achieving its desired transmission range. The temperature at which the glass can be drawn into a fiber is known as the working range, defined as (Tx-Tg), bounded by the glass transition temperature (Tg) and the crystallization temperature (Tx). In contrast to silica glasses, the working temperature range for ZBLAN glass is extremely narrow. Multiple ZBLAN samples were subjected to a heating and quenching test apparatus on the parabolic aircraft under a controlled μ-g and hyper-g environments and compared with 1-g ground tests. Optical microscopy examination elucidates that crystal growth in ZBLAN is suppressed and initiates at a later temperature when processed in a microgravity environment. Thus, the crystallization temperature, Tx, at which the crystals form has increased. The glass transition temperature, Tg, remains constant, as crystallization does not occur until approximately 360°C for this composition of ZBLAN. Therefore, the working temperature range for ZBLAN has been broadened.

  15. Non-exponential relaxation, fictive temperatures, and dispersive kinetics in the liquid-glass-liquid transition range of acetaminophen, sulfathiazole, and their mixtures

    NASA Astrophysics Data System (ADS)

    Aji, D. P. B.; Khouri, J.; Johari, G. P.

    2014-11-01

    To investigate the effects of added molecular heterogeneity on the hysteretic features of liquid-glass-liquid transition, we studied acetaminophen, sulfathiazole, and three of their mixtures by calorimetry, and determined the Tg and the fictive temperature, Tf, from changes in the enthalpy and entropy on the cooling and heating paths, as well as the non-exponential parameter, βcal. We find that, (i) Tf for cooling is within 1-3 K of Tf for heating and both are close to Tg, (ii) the closed loop entropy change in the liquid-glass-liquid range is negligibly small, (iii) Tg and Tf increase on increasing sulfathiazole in the mixture, (iv) βcal first slightly increases when the second component is added and then decreases, and (v) ageing causes deviations from a non-exponential, nonlinear behavior of the glass. In terms of fluctuations in a potential energy landscape, adding a solute heterogeneity would shift the state point to another part of the landscape with a different distribution of barrier heights and a different number of minima accessible to the state point. Part of the change in βcal is attributed to hydrogen-bond formation between the two components. Ageing changes the relaxation times distribution, more at short relaxation times than at long relaxation times, and multiplicity of relaxation modes implied by βcal < 1 indicates that each mode contributing to the enthalpy has its own Tg or Tf. βcal differs from βage determined from isothermal ageing, and the distribution parameter of α-relaxation times would differ from both βcal and βage.

  16. Improved Wide Operating Temperature Range of LiNiCoAiO2-based Li-ion Cells with Methyl Propionate-based Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Tomcsi, Michael R.; Hwang, C.; Whitcanack, L. D.; Bugga, Ratnakumar V.; Nagata, Mikito; Visco, Vince; Tsukamoto, Hisashi

    2012-01-01

    Demonstration of wide operating temperature range Li-ion electrolytes Methyl propionate-based wide operating temperature range electrolytes were demonstrated to provide dramatic improvement of the low temperature capability of Quallion prototype Li-ion cells (MCMB-LiNiCoAlO2). Some formulations were observed to deliver over 60% of the room temperature capacity using a 5C rate at - 40oC !! Represents over a 4-fold improvement over the baseline electrolyte system. Demonstrated operational capability of a number of systems over a wide temperature range (-40 to +70 C) Demonstrated reasonably good long term cycle life performance at high temperature (i.e., at +40deg and +50 C) A number of formulations containing electrolytes additives (i.e., FEC, VC, LiBOB, and lithium oxalate) have been shown to have enhanced lithium kinetics at low temperature and promising high temperature resilience. Demonstrated good performance in larger capacity (12 Ah) Quallion Li-ion cells with methyl propionate-based electrolytes. Current efforts focused upon performing life studies and the impact upon low temperature capability.

  17. A psychrotolerant strain of Serratia marcescens (MTCC 4822) produces laccase at wide temperature and pH range.

    PubMed

    Kaira, Gaurav Singh; Dhakar, Kusum; Pandey, Anita

    2015-12-01

    A psychrotolerant bacterial strain of Serratia marcescens, originally isolated from a glacial site in Indian Himalayan Region (IHR), has been investigated for laccase production under different culture conditions. The bacterial strain was found to grow between 4 to 45°C (opt. 25°C) and 3 to 14 pH (opt. 5 pH) on prescribed growth medium, coinciding with production of laccase in laccase producing medium. However, the production of laccase was more consistent toward alkaline pH. Laccase enzyme was partially purified using gel filtration chromatography. The molecular mass of laccase was determined ~53 kDa on native PAGE. The Km and Vmax values were determined to be 0.10 mM and 50.00 μM min(-1), respectively, with ABTS. Inoculum size (4.0% v/v at 1.5 O.D.) resulted in significantly higher production of laccase. Carbon and nitrogen sources also affected the laccase production significantly. All the carbon sources enhanced laccase production, xylose being the best enhancer (P < 0.01). Among nitrogen sources, organic sources were found to act as inhibitors (P < 0.01), and among the in-organic sources only sodium nitrate enhanced the laccase production. Low molecular weight organic solvents significantly (P < 0.01) enhanced laccase production up to 24 h of incubation with a decline in later incubation period. Production of laccase by the psychrotolerant bacterium in wide range of temperature and pH is likely to have inference in biotechnological processes.

  18. δ-Methyl Branching in the Side Chain Makes the Difference: Access to Room-Temperature Discotics.

    PubMed

    Kirres, Jochen; Knecht, Friederike; Seubert, Philipp; Baro, Angelika; Laschat, Sabine

    2016-04-18

    Although discotic liquid crystals are attractive functional materials, their use in electronic devices is often restricted by high melting and clearing points. Among the promising candidates for applications are [15]crown-5 ether-based liquid crystals with peripheral n-alkoxy side chains, which, however, still have melting points above room temperature. To overcome this problem, a series of o-terphenyl and triphenylene [15]crown-5 ether derivatives was prepared in which δ-methyl-branched alkoxy side chains of varying lengths substitute the peripheral linear alkoxy chains. The mesomorphic properties of the novel crown ethers were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. δ-Methyl branching indeed lowers melting points resulting in room-temperature hexagonal columnar mesophases. The mesophase widths, which ranged from 87 to 30 K for o-terphenyls, significantly increased to 106-147 K for the triphenylenes depending on the chain lengths, revealing the beneficial effect of a flat mesogen, due to improved π-π interactions.

  19. δ-Methyl Branching in the Side Chain Makes the Difference: Access to Room-Temperature Discotics.

    PubMed

    Kirres, Jochen; Knecht, Friederike; Seubert, Philipp; Baro, Angelika; Laschat, Sabine

    2016-04-18

    Although discotic liquid crystals are attractive functional materials, their use in electronic devices is often restricted by high melting and clearing points. Among the promising candidates for applications are [15]crown-5 ether-based liquid crystals with peripheral n-alkoxy side chains, which, however, still have melting points above room temperature. To overcome this problem, a series of o-terphenyl and triphenylene [15]crown-5 ether derivatives was prepared in which δ-methyl-branched alkoxy side chains of varying lengths substitute the peripheral linear alkoxy chains. The mesomorphic properties of the novel crown ethers were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. δ-Methyl branching indeed lowers melting points resulting in room-temperature hexagonal columnar mesophases. The mesophase widths, which ranged from 87 to 30 K for o-terphenyls, significantly increased to 106-147 K for the triphenylenes depending on the chain lengths, revealing the beneficial effect of a flat mesogen, due to improved π-π interactions. PMID:26853226

  20. Forced flow He vapor cooled critical current testing facility for measurements of superconductors in a wide temperature and magnetic field range

    NASA Astrophysics Data System (ADS)

    Baskys, Algirdas; Hopkins, Simon C.; Bader, Jakob; Glowacki, Bartek A.

    2016-10-01

    As superconducting materials find their way into applications, there is increasing need to verify their performance at operating conditions. Testing of critical current with respect to temperature and magnetic field is of particular importance. However, testing facilities covering a range of temperatures and magnetic fields can be costly, especially when considering the cooling power required in the cryogenic system in the temperature range below 65 K (inaccessible for LN2). Critical currents in excess of 500 A are common for commercial samples, making the testing of such samples difficult in setups cooled via a cryocooler, moreover it often does not represent the actual cooling conditions that the sample will experience in service. This work reports the design and operation of a low-cost critical current testing facility, capable of testing samples in a temperature range of 10-65 K, with magnetic field up to 1.6 T and measuring critical currents up to 900 A with variable cooling power.

  1. Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

    NASA Technical Reports Server (NTRS)

    Mckeown, A B; Belles, Frank E

    1954-01-01

    Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein.

  2. Shallow subsurface temperature surveys in the basin and range province-II. Ground temperatures in the upsal hogback geothermal area, West-Central Nevada, U.S.A.

    USGS Publications Warehouse

    Olmsted, F.H.; Ingebritsen, S.E.

    1986-01-01

    Numerous temperature surveys at a depth of 1 m were made in 1973-1985 in the Upsal Hogback and Soda Lakes geothermal areas in west-central Nevada. Whereas the surveys effectively delineated temperature at depth and heat flow within the relatively intense Soda Lakes thermal anomaly, they were not effective at the diffuse Upsal Hogback anomaly, where several perturbing factors that affect shallow subsurface temperatures are exceedingly variable. Albedo is the most important factor in the Upsal Hogback area, even at a depth of 30 m. All possible perturbing factors should be considered when designing a shallow temperature-based prospecting scheme. ?? 1986.

  3. DOES CRITICAL MASS DECREASE AS TEMPERATURE INCREASES: A REVIEW OF FIVE BENCHMARK EXPERIMENTS THAT SPAN A RANGE OF ELEVATED TEMPERATURES AND CRITICAL CONFIGURATIONS

    SciTech Connect

    Yates, K.

    2009-06-10

    Five sets of benchmark experiments are reviewed herein that cover a diverse set of fissile system configurations. The review specifically focused on the change in critical mass of these systems at elevated temperatures and the temperature reactivity coefficient ({alpha}{sub T}) on the system. Because plutonium-based critical benchmark experiments at varying temperatures were not found at the time this review was prepared, only uranium-based systems are included, as follows: (1) HEU-SOL-THERM-010 - UO{sub 2}F{sub 2} solutions with high U{sup 235} enrichment; (2) HEU-COMP-THERM-016 - uranium-graphite blocks with low U concentration; (3) LEU-COMP-THERM-032 - water moderated lattices of UO{sub 2} with stainless steel cladding, and intermediate U{sup 235} enrichment; (4) IEU-COMP-THERM-002 - water moderated lattices of annular UO{sub 2} with/without absorbers, and intermediate U{sup 235} enrichment; and (5) LEU-COMP-THERM-026 - water moderated lattices of UO{sub 2} at different pitches, and low U{sup 235} enrichment. In three of the five benchmarks (1, 3 and 5), modeling of the critical system at room temperature is conservative compared to modeling the system at elevated temperatures, i.e., a greater fissile mass is required at elevated temperature. In one benchmark (4), there was no difference in the fissile mass between the room temperature system and the system at the examined elevated temperature. In benchmark (2), the system clearly had a negative temperature reactivity coefficient. Some of the high temperature benchmark experiments were treated with appropriate (and comprehensive) adjustments to the cross section sets and thermal expansion coefficients, while other experiments were treated with partial adjustments. Regardless of the temperature treatment, modeling the systems at room temperature was found to be conservative for the examined systems, i.e., a smaller critical mass was obtained. While the five benchmarks presented herein demonstrate that, for the

  4. Note: A heated-air curtain design using the Coanda effect to protect optical access windows in high-temperature, condensing, and corrosive stack environments

    NASA Astrophysics Data System (ADS)

    Williams, Gustavious Paul; Keenan, Thomas L.; Herning, James; Kimblin, Clare; DiBenedetto, John; Anthony, Glen

    2011-01-01

    We present an air knife design for creating a heated air curtain to protect optical infrared access windows in high-temperature, condensing, and corrosive stack environments. The design uses the Coanda effect to turn the air curtain and to attach the air curtain to the window surface. The design was tested and verified on our 24 m stack and used extensively over a 6 yr period on several release stacks. During testing and subsequent use no detrimental changes to access window materials have been noted. This design allows stack monitoring without significantly affecting the stack flow profile or chemical concentration.

  5. Note: A heated-air curtain design using the Coanda effect to protect optical access windows in high-temperature, condensing, and corrosive stack environments.

    PubMed

    Williams, Gustavious Paul; Keenan, Thomas L; Herning, James; Kimblin, Clare; DiBenedetto, John; Anthony, Glen

    2011-01-01

    We present an air knife design for creating a heated air curtain to protect optical infrared access windows in high-temperature, condensing, and corrosive stack environments. The design uses the Coanda effect to turn the air curtain and to attach the air curtain to the window surface. The design was tested and verified on our 24 m stack and used extensively over a 6 yr period on several release stacks. During testing and subsequent use no detrimental changes to access window materials have been noted. This design allows stack monitoring without significantly affecting the stack flow profile or chemical concentration. PMID:21280868

  6. Development and evaluation of magnetic and electrical materials capable of operating in the 800 to 1600 F temperature range

    NASA Technical Reports Server (NTRS)

    Kueser, P. E.; Toth, J. W.

    1973-01-01

    The results are summarized of a research program on electrical materials for advanced space electric power systems. The areas investigated included improved high-temperature magnetic materials, high-temperature capacitor materials, ceramic-to-metal bore-seal technology, and simulated-space environmental testing of electric-power system components

  7. Indentation stress dependence of the temperature range of microscopic superelastic behavior of nickel-titanium thin films

    SciTech Connect

    Zhang Yijun; Cheng, Y.-T.; Grummon, David S.

    2005-08-01

    The microscopic superelastic behavior of thin-film NiTi is investigated by instrumented indentation experiments conducted at different temperatures. The indentation-induced superelastic effect is found to be persistent to about 100 K above the austenite transformation finish temperature (A{sub f}). In contrast, the upper temperature where superelastic effect exists is only around A{sub f} plus 40 K in uniaxial tension and compression tests, beyond which the plasticity of the austenite phase overwhelms the transformation-induced superelasticity. By combining the Clausius-Clapeyron equation and spherical cavity model for indentation, we show that the high hydrostatic pressure under the indenter is capable of elevating the transformation temperatures and increase the upper temperature limit of indentation-induced superelastic behavior.

  8. Free-ranging heart rate, body temperature and energy metabolism in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus) in the arid regions of South East Australia.

    PubMed

    McCarron, H C; Buffenstein, R; Fanning, F D; Dawson, T J

    2001-06-01

    Eastern grey kangaroos (Macropus giganteus) are generally regarded as mesic inhabitants. Even though access to drinking water in permanent stock watering troughs is commonly available, these animals are still found in only low densities in arid pastoral areas. We hypothesised that the differential success of red and grey kangaroos in the arid zone may be due to higher energy requirements of M. giganteus with a concomitant need for increased food, rather than limitations imposed by inadequate water access. We set out to test this by indirectly measuring energy expenditure through the monitoring of heart rate by radio telemetry in semi-free-ranging eastern grey and red kangaroos (Macropus rufus). Radio telemetry measurements of heart rate were calibrated against oxygen consumption and were used in the assessment of energy expenditure of animals maintained in an 8-ha enclosure in the arid zone of southeast Australia. Heart rate provided a reliable estimate of oxygen consumption. This well-correlated relationship was curvilinear and was established for each individual. Behavioural observations revealed that both kangaroo species spent most of the day in low energy demanding activities. M. rufus were more active at night whilst M. giganteus were more active in the early mornings and late afternoons. Like other marsupials, both species had low field metabolic rates (FMRs). However, M. giganteus in keeping with their mesic history had higher FMRs than the more arid-adapted M. rufus, particularly during water restriction. Body temperature telemeters revealed a further species difference in that under hot conditions when water is freely available, M. rufus exhibits a higher and more labile daytime body temperature than M. giganteus. During the hottest part of the day M. giganteus maintain body temperature, relying upon increased evaporative cooling mechanisms, such as licking. Indeed, only when access to drinking water was restricted was thermolability evident in M

  9. Density measurements of subcooled water in the temperature range of (243 and 283) K and for pressures up to 400 MPa.

    PubMed

    Romeo, Raffaella; Giuliano Albo, P Alberto; Lorefice, Salvatore; Lago, Simona

    2016-02-21

    In this work, accurate density measurements of subcooled water (freshly double-distilled water) were performed along eight constant-mass curves in the temperature range of (243 to 283) K and in the pressure range of (140 to 400) MPa, by a pseudo-isochoric method. The experimental apparatus mainly consisted of a high pressure vessel, especially designed for this experiment, of known volume as a function of temperature and pressure, used to perform measurements in the T-p range under study. The density of subcooled water was obtained by measuring the equilibrium pressure at different temperatures, keeping the mass constant. All terms contributing to the uncertainty of subcooled water density measurements were considered; the estimated relative uncertainty, in the investigated temperature and pressure range, is about 0.07%. The experimental results were compared with the literature densities. In particular, the trend of density versus temperature for a constant mass of sample observed experimentally differs from the trend calculated by the equation provided by the International Association for Properties of Water and Steam (IAPWS-95) outside the range of validity, i.e., in the metastable region. PMID:26896989

  10. Density measurements of subcooled water in the temperature range of (243 and 283) K and for pressures up to 400 MPa.

    PubMed

    Romeo, Raffaella; Giuliano Albo, P Alberto; Lorefice, Salvatore; Lago, Simona

    2016-02-21

    In this work, accurate density measurements of subcooled water (freshly double-distilled water) were performed along eight constant-mass curves in the temperature range of (243 to 283) K and in the pressure range of (140 to 400) MPa, by a pseudo-isochoric method. The experimental apparatus mainly consisted of a high pressure vessel, especially designed for this experiment, of known volume as a function of temperature and pressure, used to perform measurements in the T-p range under study. The density of subcooled water was obtained by measuring the equilibrium pressure at different temperatures, keeping the mass constant. All terms contributing to the uncertainty of subcooled water density measurements were considered; the estimated relative uncertainty, in the investigated temperature and pressure range, is about 0.07%. The experimental results were compared with the literature densities. In particular, the trend of density versus temperature for a constant mass of sample observed experimentally differs from the trend calculated by the equation provided by the International Association for Properties of Water and Steam (IAPWS-95) outside the range of validity, i.e., in the metastable region.

  11. Large magnetic entropy change of Gd-based ternary bulk metallic glass in liquid-nitrogen temperature range

    NASA Astrophysics Data System (ADS)

    Fu, H.; Zhang, X. Y.; Yu, H. J.; Teng, B. H.; Zu, X. T.

    2008-01-01

    Gd 60Co 26Al 14 bulk metallic glass (BMG) with a diameter of 3 mm was prepared by arc-melting and copper-mold suck-casting. X-ray diffraction (XRD) results show that the as-cast Gd 60Co 26Al 14 rod consists of a wholly amorphous phase. Differential scanning calorimetry (DSC) measurements indicated that one glass transition temperature (Tg) and two crystallization temperatures (TX) occur at 570, 602, and 642 K, respectively. Moreover, two Curie temperatures of 82 and 128 K, which correspond to the two amorphous phases in the DSC trace, were determined from the thermo-magnetization curve. The maximal magnetic entropy change (ΔSM) under 0-5 T is about 10.1 J/kg K at 75 K and the refrigerant capacity (RC) is about 556 J/kg, which makes Gd 60Co 26Al 14 BMG a promising candidate for magnetic refrigerant near liquid-nitrogen temperatures.

  12. Determination of Germination Response to Temperature and Water Potential for a Wide Range of Cover Crop Species and Related Functional Groups

    PubMed Central

    Tribouillois, Hélène; Dürr, Carolyne; Demilly, Didier; Wagner, Marie-Hélène; Justes, Eric

    2016-01-01

    A wide range of species can be sown as cover crops during fallow periods to provide various ecosystem services. Plant establishment is a key stage, especially when sowing occurs in summer with high soil temperatures and low water availability. The aim of this study was to determine the response of germination to temperature and water potential for diverse cover crop species. Based on these characteristics, we developed contrasting functional groups that group species with the same germination ability, which may be useful to adapt species choice to climatic sowing conditions. Germination of 36 different species from six botanical families was measured in the laboratory at eight temperatures ranging from 4.5–43°C and at four water potentials. Final germination percentages, germination rate, cardinal temperatures, base temperature and base water potential were calculated for each species. Optimal temperatures varied from 21.3–37.2°C, maximum temperatures at which the species could germinate varied from 27.7–43.0°C and base water potentials varied from -0.1 to -2.6 MPa. Most cover crops were adapted to summer sowing with a relatively high mean optimal temperature for germination, but some Fabaceae species were more sensitive to high temperatures. Species mainly from Poaceae and Brassicaceae were the most resistant to water deficit and germinated under a low base water potential. Species were classified, independent of family, according to their ability to germinate under a range of temperatures and according to their base water potential in order to group species by functional germination groups. These groups may help in choosing the most adapted cover crop species to sow based on climatic conditions in order to favor plant establishment and the services provided by cover crops during fallow periods. Our data can also be useful as germination parameters in crop models to simulate the emergence of cover crops under different pedoclimatic conditions and crop

  13. Determination of Germination Response to Temperature and Water Potential for a Wide Range of Cover Crop Species and Related Functional Groups.

    PubMed

    Tribouillois, Hélène; Dürr, Carolyne; Demilly, Didier; Wagner, Marie-Hélène; Justes, Eric

    2016-01-01

    A wide range of species can be sown as cover crops during fallow periods to provide various ecosystem services. Plant establishment is a key stage, especially when sowing occurs in summer with high soil temperatures and low water availability. The aim of this study was to determine the response of germination to temperature and water potential for diverse cover crop species. Based on these characteristics, we developed contrasting functional groups that group species with the same germination ability, which may be useful to adapt species choice to climatic sowing conditions. Germination of 36 different species from six botanical families was measured in the laboratory at eight temperatures ranging from 4.5-43°C and at four water potentials. Final germination percentages, germination rate, cardinal temperatures, base temperature and base water potential were calculated for each species. Optimal temperatures varied from 21.3-37.2°C, maximum temperatures at which the species could germinate varied from 27.7-43.0°C and base water potentials varied from -0.1 to -2.6 MPa. Most cover crops were adapted to summer sowing with a relatively high mean optimal temperature for germination, but some Fabaceae species were more sensitive to high temperatures. Species mainly from Poaceae and Brassicaceae were the most resistant to water deficit and germinated under a low base water potential. Species were classified, independent of family, according to their ability to germinate under a range of temperatures and according to their base water potential in order to group species by functional germination groups. These groups may help in choosing the most adapted cover crop species to sow based on climatic conditions in order to favor plant establishment and the services provided by cover crops during fallow periods. Our data can also be useful as germination parameters in crop models to simulate the emergence of cover crops under different pedoclimatic conditions and crop

  14. Determination of Germination Response to Temperature and Water Potential for a Wide Range of Cover Crop Species and Related Functional Groups.

    PubMed

    Tribouillois, Hélène; Dürr, Carolyne; Demilly, Didier; Wagner, Marie-Hélène; Justes, Eric

    2016-01-01

    A wide range of species can be sown as cover crops during fallow periods to provide various ecosystem services. Plant establishment is a key stage, especially when sowing occurs in summer with high soil temperatures and low water availability. The aim of this study was to determine the response of germination to temperature and water potential for diverse cover crop species. Based on these characteristics, we developed contrasting functional groups that group species with the same germination ability, which may be useful to adapt species choice to climatic sowing conditions. Germination of 36 different species from six botanical families was measured in the laboratory at eight temperatures ranging from 4.5-43°C and at four water potentials. Final germination percentages, germination rate, cardinal temperatures, base temperature and base water potential were calculated for each species. Optimal temperatures varied from 21.3-37.2°C, maximum temperatures at which the species could germinate varied from 27.7-43.0°C and base water potentials varied from -0.1 to -2.6 MPa. Most cover crops were adapted to summer sowing with a relatively high mean optimal temperature for germination, but some Fabaceae species were more sensitive to high temperatures. Species mainly from Poaceae and Brassicaceae were the most resistant to water deficit and germinated under a low base water potential. Species were classified, independent of family, according to their ability to germinate under a range of temperatures and according to their base water potential in order to group species by functional germination groups. These groups may help in choosing the most adapted cover crop species to sow based on climatic conditions in order to favor plant establishment and the services provided by cover crops during fallow periods. Our data can also be useful as germination parameters in crop models to simulate the emergence of cover crops under different pedoclimatic conditions and crop

  15. Electron spin lattice relaxation of nitroxyl radicals in temperature ranges that span glassy solutions to low-viscosity liquids

    NASA Astrophysics Data System (ADS)

    Sato, Hideo; Bottle, Steven E.; Blinco, James P.; Micallef, Aaron S.; Eaton, Gareth R.; Eaton, Sandra S.

    2008-03-01

    Electron spin-lattice relaxation rates, 1/ T1, at X-band of nitroxyl radicals (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-oxyl and 3-carbamoyl-2,2,5,5-tetramethylpyrrolin-1-oxyl) in glass-forming solvents (decalin, glycerol, 3-methylpentane, o-terphenyl, 1-propanol, sorbitol, sucrose octaacetate, and 1:1 water:glycerol) at temperatures between 100 and 300 K were measured by long-pulse saturation recovery to investigate the relaxation processes in slow-to-fast tumbling regimes. A subset of samples was also studied at lower temperatures or at Q-band. Tumbling correlation times were calculated from continuous wave lineshapes. Temperature dependence and isotope substitution ( 2H and 15N) were used to distinguish the contributions of various processes. Below about 100 K relaxation is dominated by the Raman process. At higher temperatures, but below the glass transition temperature, a local mode process makes significant contributions. Above the glass transition temperature, increased rates of molecular tumbling modulate nuclear hyperfine and g anisotropy. The contribution from spin rotation is very small. Relaxation rates at X-band and Q-band are similar. The dependence of 1/ T1 on tumbling correlation times fits better with the Cole-Davidson spectral density function than with the Bloembergen-Purcell-Pound model.

  16. Effect of nitrogen sorption mechanisms on the properties of fullerite C60 over a wide range of temperatures

    NASA Astrophysics Data System (ADS)

    Legchenkova, I. V.; Yagotintsev, K. A.; Galtsov, N. N.; Meleshko, V. V.; Stetsenko, Yu. E.; Prokhvatilov, A. I.

    2014-08-01

    X-ray diffractometry is used to study the effect of the adsorption of nitrogen at a pressure of 30 atm and temperatures of 200-550 °C on the structural and thermodynamic properties of fullerite C60. The sorption kinetics of nitrogen at different temperatures are studied, and the lattice parameter is plotted as a function of the time for fullerite to saturate with nitrogen. The sorption mechanism is found to change with increasing saturation temperature. The diffusive filling of lattice octahedral voids by nitrogen atoms at temperatures below 450 °C is supplanted at higher temperatures by a chemical interaction of nitrogen with fullerite molecules leading to the formation of a new molecular compound, fullerite nitride C60Nx. The transition from physisorption to chemisorption of nitrogen by fullerite (the adsorption crossover) takes place at saturation temperatures of 450 > T > 400 °C. When C60 molecules are nitrogenated, the volume of the cubic cell increases dramatically, while the intensity of the x-ray reflections decreases and their width increases rapidly. The limiting distortions of the fcc lattice are determined, as well as the characteristic times for diffusional filling of the lattice voids and for nitrogenation, respectively, during physical and chemical sorption of nitrogen. Nitrogenation of fullerite molecules leads to a significant reduction in thermal expansion of the crystalline material, and suppresses both the orientational phase transition and formation of the glassy state.

  17. Temperature dependent dielectric function in the near-infrared to vacuum-ultraviolet ultraviolet spectral range of alumina and yttria stabilized zirconia thin films

    SciTech Connect

    Schmidt-Grund, R. Lühmann, T.; Böntgen, T.; Franke, H.; Lorenz, M.; Grundmann, M.; Opper, D.

    2013-12-14

    The dielectric function of nano-/polycrystalline alumina and yttria stabilised zirconia thin films has been investigated in a wide spectral range from 1.0 eV to 7.5 eV and temperatures between 10 K and room temperature. In the near band-edge spectral range, we found a broad distribution of optical transitions within the band gap, the so-called Urbach absorption tail which is typical for amorphous or polycrystalline materials due to the lack of long range order in the crystal structure. The coupling properties of the electronic system to the optical phonon bath and thermal lattice vibrations strongly depend on the ratio of the spectral extent of these disorder states to the main phonon energy, which we correlate with the different crystalline structure of our samples. The films have been grown at room temperature and 650 °C by pulsed laser deposition.

  18. Effect of daily temperature range on respiratory health in Argentina and its modification by impaired socio-economic conditions and PM10 exposures.

    PubMed

    Carreras, Hebe; Zanobetti, Antonella; Koutrakis, Petros

    2015-11-01

    Epidemiological investigations regarding temperature influence on human health have focused on mortality rather than morbidity. In addition, most information comes from developed countries despite the increasing evidence that climate change will have devastating impacts on disadvantaged populations living in developing countries. In the present study, we assessed the impact of daily temperature range on upper and lower respiratory infections in Cordoba, Argentina, and explored the effect modification of socio-economic factors and influence of airborne particles We found that temperature range is a strong risk factor for admissions due to both upper and lower respiratory infections, particularly in elderly individuals, and that these effects are more pronounced in sub-populations with low education level or in poor living conditions. These results indicate that socio-economic factors are strong modifiers of the association between temperature variability and respiratory morbidity, thus they should be considered in risk assessments.

  19. Effect of daily temperature range on respiratory health in Argentina and its modification by impaired socio-economic conditions and PM10 exposures

    PubMed Central

    Carreras, Hebe; Zanobetti, Antonella; Koutrakis, Petros

    2016-01-01

    Epidemiological investigations regarding temperature influence on human health have focused on mortality rather than morbidity. In addition, most information comes from developed countries despite the increasing evidence that climate change will have devastating impacts on disadvantaged populations living in developing countries. In the present study, we assessed the impact of daily temperature range on upper and lower respiratory infections in Cordoba, Argentina, and explored the effect modification of socio-economic factors and influence of airborne particles We found that temperature range is a strong risk factor for admissions due to both upper and lower respiratory infections, particularly in elderly individuals, and that these effects are more pronounced in sub-populations with low education level or in poor living conditions. These results indicate that socio-economic factors are strong modifiers of the association between temperature variability and respiratory morbidity, thus they should be considered in risk assessments. PMID:26164202

  20. The corrosion of etched magnox Al-80 in dry steam at ˜ 10 5 Pa pressure in the temperature range 373-573 K

    NASA Astrophysics Data System (ADS)

    Friskney, C. A.

    1981-09-01

    The corrosion of magnox in dry steam has been studied isothermally in the temperature range 373-573 K. Within this range different products dominate the process and there are corresponding rate changes. At ~520 K and above the product is magnesium oxide, whilst below ~ 393 K magnesium hydroxide is produced, the corrosion rate increasing with temperature in both regimes. Although magnesium hydroxide remains the dominant reaction product from 395 to 497 K, the rate of corrosion passes through a maximum at ~ 409 K and then falls rapidly as temperature is increased to ~ 520 K. Above 440 K magnesium hydride is detectable in the corrosion product, the amount increasing with temperature. It is suggested that hydrogen is built up in traps near the metal surface to form hydride and the hydride/hydrogen slows the hydroxide production. Formation of magnesium oxide appears to be a relatively slow process compared with hydroxide formation.

  1. Cardiac activation heat remains inversely dependent on temperature over the range 27-37°C.

    PubMed

    Johnston, Callum M; Han, June-Chiew; Loiselle, Denis S; Nielsen, Poul M F; Taberner, Andrew J

    2016-06-01

    The relation between heat output and stress production (force per cross-sectional area) of isolated cardiac tissue is a key metric that provides insight into muscle energetic performance. The heat intercept of the relation, termed "activation heat," reflects the metabolic cost of restoring transmembrane gradients of Na(+) and K(+) following electrical excitation, and myoplasmic Ca(2+) concentration following its release from the sarcoplasmic reticulum. At subphysiological temperatures, activation heat is inversely dependent on temperature. Thus one may presume that activation heat would decrease even further at body temperature. However, this assumption is prima facie inconsistent with a study, using intact hearts, which revealed no apparent change in the combination of activation and basal metabolism between 27 and 37°C. It is thus desired to directly determine the change in activation heat between 27 and 37°C. In this study, we use our recently constructed high-thermal resolution muscle calorimeter to determine the first heat-stress relation of isolated cardiac muscle at 37°C. We compare the relation at 37°C to that at 27°C to examine whether the inverse temperature dependence of activation heat, observed under hypothermic conditions, prevails at body temperature. Our results show that activation heat was reduced (from 3.5 ± 0.3 to 2.3 ± 0.3 kJ/m(3)) at the higher temperature. This leads us to conclude that activation metabolism continues to decline as temperature is increased from hypothermia to normothermia and allows us to comment on results obtained from the intact heart by previous investigators.

  2. Laboratory calibration of the calcium carbonate clumped isotope thermometer in the 25-250 °C temperature range

    NASA Astrophysics Data System (ADS)

    Kluge, Tobias; John, Cédric M.; Jourdan, Anne-Lise; Davis, Simon; Crawshaw, John

    2015-05-01

    Many fields of Earth sciences benefit from the knowledge of mineral formation temperatures. For example, carbonates are extensively used for reconstruction of the Earth's past climatic variations by determining ocean, lake, and soil paleotemperatures. Furthermore, diagenetic minerals and their formation or alteration temperature may provide information about the burial history of important geological units and can have practical applications, for instance, for reconstructing the geochemical and thermal histories of hydrocarbon reservoirs. Carbonate clumped isotope thermometry is a relatively new technique that can provide the formation temperature of carbonate minerals without requiring a priori knowledge of the isotopic composition of the initial solution. It is based on the temperature-dependent abundance of the rare 13C-18O bonds in carbonate minerals, specified as a Δ47 value. The clumped isotope thermometer has been calibrated experimentally from 1 °C to 70 °C. However, higher temperatures that are relevant to geological processes have so far not been directly calibrated in the laboratory. In order to close this calibration gap and to provide a robust basis for the application of clumped isotopes to high-temperature geological processes we precipitated CaCO3 (mainly calcite) in the laboratory between 23 and 250 °C. We used two different precipitation techniques: first, minerals were precipitated from a CaCO3 supersaturated solution at atmospheric pressure (23-91 °C), and, second, from a solution resulting from the mixing of CaCl2 and NaHCO3 in a pressurized reaction vessel at a pressure of up to 80 bar (25-250 °C). The calibration lines of both experimental approaches overlap and agree in the slopes with theoretical estimates and with other calibration experiments in which carbonates were reacted with phosphoric acid at temperatures above 70 °C. Our study suggests a universal Δ47-T calibration (T in K, Δ47 in ‰):

  3. Cardiac activation heat remains inversely dependent on temperature over the range 27-37°C.

    PubMed

    Johnston, Callum M; Han, June-Chiew; Loiselle, Denis S; Nielsen, Poul M F; Taberner, Andrew J

    2016-06-01

    The relation between heat output and stress production (force per cross-sectional area) of isolated cardiac tissue is a key metric that provides insight into muscle energetic performance. The heat intercept of the relation, termed "activation heat," reflects the metabolic cost of restoring transmembrane gradients of Na(+) and K(+) following electrical excitation, and myoplasmic Ca(2+) concentration following its release from the sarcoplasmic reticulum. At subphysiological temperatures, activation heat is inversely dependent on temperature. Thus one may presume that activation heat would decrease even further at body temperature. However, this assumption is prima facie inconsistent with a study, using intact hearts, which revealed no apparent change in the combination of activation and basal metabolism between 27 and 37°C. It is thus desired to directly determine the change in activation heat between 27 and 37°C. In this study, we use our recently constructed high-thermal resolution muscle calorimeter to determine the first heat-stress relation of isolated cardiac muscle at 37°C. We compare the relation at 37°C to that at 27°C to examine whether the inverse temperature dependence of activation heat, observed under hypothermic conditions, prevails at body temperature. Our results show that activation heat was reduced (from 3.5 ± 0.3 to 2.3 ± 0.3 kJ/m(3)) at the higher temperature. This leads us to conclude that activation metabolism continues to decline as temperature is increased from hypothermia to normothermia and allows us to comment on results obtained from the intact heart by previous investigators. PMID:27016583

  4. Evaluation of a 2.5 kWel automotive low temperature PEM fuel cell stack with extended operating temperature range up to 120 °C

    NASA Astrophysics Data System (ADS)

    Ruiu, Tiziana; Dreizler, Andreas M.; Mitzel, Jens; Gülzow, Erich

    2016-01-01

    Nowadays, the operating temperature of polymer electrolyte membrane fuel cell stacks is typically limited to 80 °C due to water management issues of membrane materials. In the present work, short-term operation at elevated temperatures up to 120 °C and long-term steady-state operation under automotive relevant conditions at 80 °C are examined using a 30-cell stack developed at DLR. The high temperature behavior is investigated by using temperature cycles between 90 and 120 °C without adjustment of the gases dew points, to simulate a short-period temperature increase, possibly caused by an extended power demand and/or limited heat removal. This galvanostatic test demonstrates a fully reversible performance decrease of 21 ± 1% during each thermal cycle. The irreversible degradation rate is about a factor of 6 higher compared to the one determined by the long-term test. The 1200-h test at 80 °C demonstrates linear stack voltage decay with acceptable degradation rate, apart from a malfunction of the air compressor, which results in increased catalyst degradation effects on individual cells. This interpretation is based on an end-of-life characterization, aimed to investigate catalyst, electrode and membrane degradation, by determining hydrogen crossover rates, high frequency resistances, electrochemically active surface areas and catalyst particle sizes.

  5. Adhesive As-S-Se-I immersion lenses for enhancing radiation characteristics of mid-IR LEDs operating in wide temperature range

    NASA Astrophysics Data System (ADS)

    Markov, Viktor A.; Semencha, Alexandr V.; Kurushkin, Mikhail V.; Kurushkin, Dmitry V.; Klinkov, Viktor A.; Petukhov, Andrey A.

    2016-09-01

    The influence of As-S-Se-I chalcogenide glass lenses on the integral and spectral power and pattern of LED radiation has been shown. Simulation of the influence of the refractive index on the integral power for two lens shapes has been performed. The wettability and adhesion force of As-S-Se-I melt has been determined for several electronic engineering materials. Mechanical stresses between chalcogenide glass and adjacent diode body materials have been calculated for -100 to 53 °C temperature range. Stability of the immersion lenses against cracking has been experimentally investigated for -150 to 53 °C temperature range.

  6. Comparison of clumped isotope signatures of dolomite cements to fluid inclusion thermometry in the temperature range of 74-180 °C

    NASA Astrophysics Data System (ADS)

    Came, R. E.; Azmy, K.; Tripati, A. K.

    2015-12-01

    Widespread application of the novel clumped isotope paleothermometer (Δ47) using carbonate samples from shallow crustal settings has been hindered by a lack of knowledge about clumped isotope systematics in carbonate minerals forming at temperatures greater than 50ºC. Furthermore, the utility of the Δ47 proxy in the mineral dolomite is limited because calibration data for dolomites that formed at any temperature are lacking. Consequently, applications involving diagenetic temperatures have required extrapolations beyond the range of most Δ47-temperature calibrations. Here we compare Δ47 values in dolomite cements to temperatures independently determined using fluid-inclusion microthermometry, and compare this rock-based "calibration" to previously published laboratory-derived calibrations for synthetic carbonates. This combination of approaches yields results that are consistent with the shallow calibration slope that has been reported from some laboratory experiments.

  7. Unroofing of fore-arc ranges along the Hikurangi Margin, New Zealand: Constraints from low-temperature thermochronology

    NASA Astrophysics Data System (ADS)

    Jiao, Ruohong; Seward, Diane; Little, Timothy A.; Kohn, Barry P.

    2015-08-01

    The Axial Ranges of North Island, New Zealand, parallel the Hikurangi subduction margin. They consist of uplifted and exhumed Mesozoic meta-sedimentary basement rocks of the overriding Australian Plate, beneath which the Pacific Plate has been subducting since at least the Late Oligocene. We investigate the unroofing histories of these fore-arc mountains during the evolution of the Hikurangi Margin, based on new and previous zircon and apatite fission-track, and apatite (U-Th-Sm)/He data which we interpret based on inverse modelling. The results suggest that the exhumation of rocks in the Axial Ranges initiated in the west and migrated trench-wards towards the east. Onsets of accelerated exhumation in different parts of the ranges indicate significant eastwards thrusting on the margin-parallel Ngamatea Fault before ~ 20-17 Ma and on the Wellington-Mohaka Fault before ~ 10-7 Ma. The exhumation rate has varied significantly along-strike since the Late Miocene, lower in the central part of the Axial Ranges and significantly higher to the south. Since the Late Miocene, the increasing exhumation rate from the central to southern Axial Ranges is consistent with the clockwise vertical-axis rotation of eastern North Island relative to the Australian Plate. In the Hikurangi Margin, although underplating of subducted material at the basal upper plate may have contributed to localised rock uplift (e.g., in the Raukumara Range), we suggest that the shortening of the fore-arc upper plate was the chief driver of unroofing of the (proto-) Axial Ranges.

  8. Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications

    PubMed Central

    Gupta, Ram K.; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

    2015-01-01

    Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures. PMID:26482921

  9. Differential growth of Legionella pneumophila strains within a range of amoebae at various temperatures associated with in-premise plumbing

    EPA Science Inventory

    The potential effect of in-premise plumbing temperatures (24, 32, 37 and 41 °C) on the growth of five different L. pneumophila strains within free-living amoebae (Acanthamoeba polyphaga, Hartmannella vermiformis and Naegleria fowleri) was examined. Compared to controls only fed E...

  10. Front curvature rate stick measurements and detonation shock dynamics calibration for PBX 9502 over a wide temperature range

    SciTech Connect

    Hill, L.G.; Bdzil, J.B.; Aslam, T.D.

    1998-12-31

    Detonation velocity and wave shape are measured for PBX 9502 (95 wt.% TATB, 5 wt.% Kel-F 800) rate sticks at the temperatures {minus}55, 25, and 75 C. At each temperature three different diameters were fired: 50 mm, 18 mm, and 8, 10, and 12 mm respectively for the hot, ambient, and cold sticks. The measured wave shapes are fit with an analytic form and the fitting parameters are tabulated along with thermal expansion and diameter effect data. The simplest detonation shock dynamics (DSD) model assumes a unique calibration function relating the local normal wave speed D{sub n} to the local total curvature {kappa}. The data confirm this notion for sufficiently small curvature, but at large curvature the curves for different charge diameters diverge. Global optimization is used to determine a best single D{sub n}-{kappa} function at each initial temperature T{sub 0}. From these curves a D{sub n}({kappa},T{sub 0}) calibration surface is generated that allows computation of problems with temperature gradients.

  11. Douglas-fir displays a range of growth responses to temperature, water, and Swiss needle cast in western Oregon, USA

    EPA Science Inventory

    Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) growth in the Pacific Northwest is affected by climatic, edaphic factors and Swiss needle cast (SNC) disease. We examine Douglas-fir growth responses to temperature, dewpoint deficit (DPD), soil moisture, and SNC ...

  12. Lightweight, all-metal hose assembly has high flexibility and strength over wide range of temperature and pressure

    NASA Technical Reports Server (NTRS)

    Bessing, L. L.

    1966-01-01

    Lightweight flexible, metal braid reinforced hose assembly is used in high and low pressure oxygen, helium, and hydrogen systems. These hose assemblies have been successfully used on the Saturn-2 stage to provide joints of sufficient flexibility to absorb movement resulting from temperature variations.

  13. Photosynthetic and stomatal responses to high temperature and light in two oaks at the western limit of their range.

    PubMed

    Hamerlynck, E; Knapp, A K

    1996-06-01

    Bur oak (Quercus macrocarpa Michx.) and chinquapin oak (Q. muehlenbergii Engl.) leaves were exposed to high temperatures at various photosynthetic photon flux densities under laboratory conditions to determine if species-specific responses to these factors were consistent with the distribution of these oaks in gallery forests in the tallgrass prairies of northeastern Kansas, USA. Measurements of the ratio of chlorophyll fluorescence decrease, R(fd), indicated that chinquapin oak maintained greater photosynthetic capacity than bur oak across all tested combinations of irradiance (100, 400, 700 and 1000 micro mol m(-2) s(-1)) and temperature (40, 42, 44, 46 and 48 degrees C). In both oak species, manipulation of leaf temperature to about 47 degrees C for 45 min in the field led to a 45% decrease in carbon assimilation up to one week after the heat treatment, and to sharp reductions in stomatal conductance. Photosynthetic recovery patterns indicated that bur oak took longer to recover from heat stress than chinquapin oak, suggesting that heat stress may be important in determining distribution patterns of these oak species. Based on a comparison of the results with data from other forest species, we conclude that the photosynthetic temperature tolerances of bur oak and chinquapin oaks facilitate their dominance at the western limit of the eastern deciduous forest.

  14. The interrelationship between dengue incidence and diurnal ranges of temperature and humidity in a Sri Lankan city and its potential applications

    PubMed Central

    Ehelepola, N. D. B.; Ariyaratne, Kusalika

    2015-01-01

    Background Temperature, humidity, and other weather variables influence dengue transmission. Published studies show how the diurnal fluctuations of temperature around different mean temperatures influence dengue transmission. There are no published studies about the correlation between diurnal range of humidity and dengue transmission. Objective The goals of this study were to determine the correlation between dengue incidence and diurnal fluctuations of temperature and humidity in the Sri Lankan city of Kandy and to explore the possibilities of using that information for better control of dengue. Design We calculated the weekly dengue incidence in Kandy during the period 2003–2012, after collecting data on all of the reported dengue patients and estimated midyear populations. Data on daily maximum and minimum temperatures and night-time and daytime humidity were obtained from two weather stations, averaged, and converted into weekly data. The number of days per week with a diurnal temperature range (DTR) of >10°C and <10°C and the number of days per week with a diurnal humidity range (DHR) of >20 and <15% were calculated. Wavelet time series analysis was performed to determine the correlation between dengue incidence and diurnal ranges of temperature and humidity. Results There were negative correlations between dengue incidence and a DTR >10°C and a DHR >20% with 3.3-week and 4-week lag periods, respectively. Additionally, positive correlations between dengue incidence and a DTR <10°C and a DHR <15% with 3- and 4-week lag periods, respectively, were discovered. Conclusions These findings are consistent with the results of previous entomological studies and theoretical models of DTR and dengue transmission correlation. It is important to conduct similar studies on diurnal fluctuations of humidity in the future. We suggest ways and means to use this information for local dengue control and to mitigate the potential effects of the ongoing global reduction of

  15. Determination of partial thermodynamic functions of (YBa 2Cu 3)O 6.5+x in the 700-1200 K temperature range

    NASA Astrophysics Data System (ADS)

    Toci, F.; Schürenkämper, A.; Cambini, M.; Manes, L.

    1988-06-01

    Thermodynamic functions of superconducting (YBa2Cu3)O6.5+x have been determined in the temperature range 700-1200 K making use of a solid-state galvanic cell. At all oxygen contents investigated, transitions have been observed and a tentative interpretation is provided. Entropy is correlated with enthalpy, indicating a strong interaction between oxygen vacancies.

  16. Measurement and Estimation of High-Vacuum Effective Thermal Conductivity of Polyimide Foam in the Temperature Range from 160 K to 370 K for Outer Space Applications

    NASA Astrophysics Data System (ADS)

    Takagi, Ryuichi; Tachikawa, Sumitaka; Ohmura, Takahiro; Nagasaka, Yuji

    2014-02-01

    Polyimide foam (PF) is a low-thermal conductivity and lightweight material with high resistances against heat, protons, and UV irradiation. A new thermal insulation composed of PFs and multiple aluminized films (PF-MLI) has potential to be used in outer space as an alternative to conventional multilayer insulation (MLI). As fundamental numerical data, the effective thermal conductivity of PF in wide ranges of density and temperature need to be determined. In the present study, thermal-conductivity measurements were performed by both the periodic heating method and the guarded hot-plate method in the temperature range from 160 K to 370 K and the density range from 6.67 to 242.63 . The experiments were carried out in a vacuum and under atmospheric pressure. For confirmation of the validity of the present guarded hot-plate apparatus under atmospheric pressure, the effective thermal conductivity of the lowest-density PF was measured with the aid of the heat flow meter apparatus calibrated by the standard reference material (NIST SRM 1450c) in the temperature range from 303 K to 323 K. In order to cross-check the present experimental results, the temperature and density dependences of the effective thermal conductivity of PF were estimated by means of the lattice Boltzmann method based on a dodecahedron inner microscopic complex structure model which reflects a real 3D X-ray CT image of PF.

  17. The workability of commercial and experimental 0.6 pct carbon low alloy steels in the temperature range of 650 °C to 870 °C

    NASA Astrophysics Data System (ADS)

    Matuszewski, T.; McQueen, H. J.; Machmeier, P. M.

    1994-04-01

    The torsional strength and ductility of commercial AlSI 4063 steel along with four 0.6 pct carbon, low alloy experimental steel compositions were determined with temperature. These parameters were then related to the workability of the steels. The influence of initial lamellar or spheroidal microstructures, as well as of vacuum or air-melt practices, were studied in the deformation temperature range of 650 °C to 870 °C and strain-rate range of 0.71 to 2.13 s-1 The experimental steels showed increased ductility and lower peak flow stresses over the entire temperature range when compared to the commercial alloy. Lamellar microstructures resulted in higher maximum flow stresses and subsequent work softening in the ferritic regime. Initial carbide morphology did not influence the maximum flow stresses in the austenitic range. Improved ductility of the experimental steels over the entire working temperatures could possibly be attributed to the combination of a reduced amount of oxides and sulfides, reduced particleto-matrix decohesion, improved grain-boundary cohesion, or the ability to annihilate or heal microcracks which may form during deformation. Constitutive equations were developed for the ferritic and austenitic conditions with both spheroidized and lamellar carbides.

  18. Phase diagram of the eutectic benzoic acid-naphthalene system in the temperature range of 300-400 K

    NASA Astrophysics Data System (ADS)

    Postnikov, V. A.

    2014-08-01

    Liquid-solid phase equilibria are studied in the eutectic benzoic acid-naphthalene system by means of thermic analysis (DTA, CTA), on the basis of which the liquidus line and eutectic point ( x e ≈ 50 mol %, T e ± 340 K) are determined and the phase diagram is constructed. Average precrystallization supercooling temperatures Δ T {L/-} of the liquid phase relative to liquidus temperature T L are determined, allowing us to locate the region of solution metastability on the phase diagram. Excessive functions of the components in the liquid phase are found via thermodynamic modeling using the Margules equation and experimental data. The boundaries of the region of liquid solution metastability are estimated from the thermodynamic conditions of solution stability.

  19. Unrestrained swelling of uranium-nitride fuel irradiated at temperatures ranging from 1100 to 1400 K (1980 to 2520 R)

    NASA Technical Reports Server (NTRS)

    Rohal, R. G.; Tambling, T. N.

    1973-01-01

    Six fuel pins were assembled, encapsulated, and irradiated in the Plum Brook Reactor. The fuel pins employed uranium mononitride (UN) in a stainless steel (type 304L) clad. The pins were irradiated for approximately 4000 hours to burnups of about 2.0 atom percent uranium. The average clad surface temperature during irradiation was about 1100 K (1980 deg R). Since stainless steel has a very low creep strength relative to that of UN at this temperature, these tests simulated unrestrained swelling of UN. The tests indicated that at 1 percent uranium atom burnup the unrestrained diametrical swelling of UN is about 0.5, 0.8, and 1.0 percent at 1223, 1264, and 1306 K (2200, deg 2273 deg, and 2350 deg R), respectively. The tests also indicated that the irradiation induced swelling of unrestrained UN fuel pellets appears to be isotropic.

  20. Measurement of thermal conductivity of granular materials over a wide range of temperatures. Comparison with theoretical models

    NASA Astrophysics Data System (ADS)

    Malherbe, G.; Henry, J.-F.; El Bakali, A.; Bissieux, C.; Fohanno, S.

    2012-11-01

    This study is devoted to the measurement of thermal conductivity of granular materials. The materials studied are foundry sand and steel shot. These measurements are performed at high temperature (up to 640°C) by an unsteady state method using a cartridge heater as heating element. Then, experimental results are faced with three analytical models giving the effective thermal conductivity of granular materials. The thermal effusivity of these granular materials is also estimated.

  1. Ignition Delays of Alkyl Thiophosphites with White and Red Fuming Nitric Acids Within Temperature Range 80 to -105 F

    NASA Technical Reports Server (NTRS)

    Miller, Riley O; Ladanyi, Dezso J

    1953-01-01

    Ignition delays of alkyl thiophosphites were obtained in a modified open-cup apparatus and a small-scale rocket engine apparatus. At -40 F, mixed alkyl thiophosphites gave short delays with white fuming nitric acid containing 2 percent water and red fuming nitric acids of widely varying compositions. At -40 F and higher, triethyl trithiophosphite blended with as much as 40 percent n-heptane gave satisfactory self-igniting properties at temperatures as low as -76 F.

  2. The Mechanical Properties of Wood of Different Moisture Content Within -200 Degrees to +200 Degrees C Temperature Range

    NASA Technical Reports Server (NTRS)

    Kollmann, Franz

    1941-01-01

    Systematic experiments were undertaken with special reference to the effect of gross specific weight (specific weight inclusive of pores) and the moisture content of wood. It was found that the modules of elasticity of wood at room temperature and frozen at -8 degrees is practically the same. The effect of moisture on the compression strength of frozen wood was explored as well as the flexural and impact strength of frozen wood and frozen laminated wood.

  3. Density and viscosity of 1,7-dibromoheptane-ethanol solutions in a temperature range 288-323 K

    NASA Astrophysics Data System (ADS)

    Li, Hua; Zhou, Jinliang; Chen, Xiao-Shuang

    2012-10-01

    The densities and viscosities of pure 1,7-dibromoheptane and 1,7-dibromoheptane in ethanol had been determined in a range from 288.15 to 323.15 K. The relative viscosities were correlated using the extended Jones-Dole equation. The results showed that the model agreed very well with the experimental data.

  4. GASEOUS MEAN OPACITIES FOR GIANT PLANET AND ULTRACOOL DWARF ATMOSPHERES OVER A RANGE OF METALLICITIES AND TEMPERATURES

    SciTech Connect

    Freedman, Richard S.; Lustig-Yaeger, Jacob; Fortney, Jonathan J.; Lupu, Roxana E.; Marley, Mark S.; Lodders, Katharina

    2014-10-01

    We present new calculations of Rosseland and Planck gaseous mean opacities relevant to the atmospheres of giant planets and ultracool dwarfs. Such calculations are used in modeling the atmospheres, interiors, formation, and evolution of these objects. Our calculations are an expansion of those presented in Freedman et al. to include lower pressures, finer temperature resolution, and also the higher metallicities most relevant for giant planet atmospheres. Calculations span 1 μbar to 300 bar, and 75-4000 K, in a nearly square grid. Opacities at metallicities from solar to 50 times solar abundances are calculated. We also provide an analytic fit to the Rosseland mean opacities over the grid in pressure, temperature, and metallicity. In addition to computing mean opacities at these local temperatures, we also calculate them with weighting functions up to 7000 K, to simulate the mean opacities for incident stellar intensities, rather than locally thermally emitted intensities. The chemical equilibrium calculations account for the settling of condensates in a gravitational field and are applicable to cloud-free giant planet and ultracool dwarf atmospheres, but not circumstellar disks. We provide our extensive opacity tables for public use.

  5. Ratiometric highly sensitive luminescent nanothermometers working in the room temperature range. Applications to heat propagation in nanofluids.

    PubMed

    Brites, Carlos D S; Lima, Patrícia P; Silva, Nuno J O; Millán, Angel; Amaral, Vitor S; Palacio, Fernando; Carlos, Luís D

    2013-08-21

    There is an increasing demand for accurate, non-invasive and self-reference temperature measurements as technology progresses into the nanoscale. This is particularly so in micro- and nanofluidics where the comprehension of heat transfer and thermal conductivity mechanisms can play a crucial role in areas as diverse as energy transfer and cell physiology. Here we present two luminescent ratiometric nanothermometers based on a magnetic core coated with an organosilica shell co-doped with Eu(3+) and Tb(3+) chelates. The design of the hybrid host and chelate ligands permits the working of the nanothermometers in a nanofluid at 293-320 K with an emission quantum yield of 0.38 ± 0.04, a maximum relative sensitivity of 1.5% K(-1) at 293 K and a spatio-temporal resolution (constrained by the experimental setup) of 64 × 10(-6) m/150 × 10(-3) s (to move out of 0.4 K--the temperature uncertainty). The heat propagation velocity in the nanofluid, (2.2 ± 0.1) × 10(-3) m s(-1), was determined at 294 K using the nanothermometers' Eu(3+)/Tb(3+) steady-state spectra. There is no precedent of such an experimental measurement in a thermographic nanofluid, where the propagation velocity is measured from the same nanoparticles used to measure the temperature. PMID:23835484

  6. WRF-simulated sensitivity to land surface schemes in short and medium ranges for a high-temperature event in East China: A comparative study

    NASA Astrophysics Data System (ADS)

    Zeng, Xin-Min; Wang, Ning; Wang, Yang; Zheng, Yiqun; Zhou, Zugang; Wang, Guiling; Chen, Chaohui; Liu, Huaqiang

    2015-09-01

    We designed simulations for the high-temperature event that occurred on 23 July 2003 in East China using a series of forecast lead times, from short-range to medium-range, and four land surface schemes (LSSs) (i.e., SLAB, NOAH, RUC, and PX) in the Weather Research and Forecasting Model (WRF), Version 3. The sensitivities of short and medium-range simulations to the LSSs systematically varied with the lead times. In general, the model reproduced short-range, high-temperature distributions. The simulated weather was sensitive to the LSSs, and the LSS-induced sensitivity was higher in the medium range than in the short-range. Furthermore, the LSS performances were complex, i.e., the PX errors apparently increased in the medium range (longer than 6 days), RUC produced the maximum errors, and SLAB and NOAH had approximately equivalent errors that slightly increased. Additional sensitivity simulations revealed that the WRF modeling system assigns relatively low initial soil moisture for RUC and that soil moisture initialization plays an important role that is comparable to the LSS choice in the simulations. LSS-induced negative feedback between surface air temperature (SAT) and atmospheric circulation in the lower atmosphere was found in the medium range. These sensitivities were mainly caused by the LSS-induced differences in surface sensible heat flux and by errors associated with the lead times. Using the SAT equation, further diagnostic analyses revealed LSS deficiencies in simulating surface fluxes and physical processes that modify the SAT and indicated the main reasons for these deficiencies. These results have implications for model improvement and application.

  7. Confidence intervals for time averages in the presence of long-range correlations, a case study on Earth surface temperature anomalies

    NASA Astrophysics Data System (ADS)

    Massah, M.; Kantz, H.

    2016-09-01

    Time averages, a standard tool in the analysis of environmental data, suffer severely from long-range correlations. The sample size needed to obtain a desired small confidence interval can be dramatically larger than for uncorrelated data. We present quantitative results for short- and long-range correlated Gaussian stochastic processes. Using these, we calculate confidence intervals for time averages of surface temperature measurements. Temperature time series are well known to be long-range correlated with Hurst exponents larger than 1/2. Multidecadal time averages are routinely used in the study of climate change. Our analysis shows that uncertainties of such averages are as large as for a single year of uncorrelated data.

  8. A high temperature fatigue life prediction computer code based on the total strain version of StrainRange Partitioning (SRP)

    NASA Technical Reports Server (NTRS)

    Mcgaw, Michael A.; Saltsman, James F.

    1993-01-01

    A recently developed high-temperature fatigue life prediction computer code is presented and an example of its usage given. The code discussed is based on the Total Strain version of Strainrange Partitioning (TS-SRP). Included in this code are procedures for characterizing the creep-fatigue durability behavior of an alloy according to TS-SRP guidelines and predicting cyclic life for complex cycle types for both isothermal and thermomechanical conditions. A reasonably extensive materials properties database is included with the code.

  9. The temperature dependence of the resistivity of ohmic contacts based on gallium arsenide and indium phosphide in the 4.2-300 K range

    NASA Astrophysics Data System (ADS)

    Sachenko, A. V.; Belyaev, A. E.; Boltovets, N. S.; Konakova, R. V.; Vitusevich, S. A.; Novitskii, S. V.; Sheremet, V. N.; Pilipchuk, A. S.

    2016-06-01

    Resistivity ρc of InP- and GaAs-based ohmic contacts has been measured in a temperature range of 4.2-300 K. Both temperature dependences are nonmonotonic and exhibit minima at T = 50 K for InP and T = 150 K for GaAs. The nonmonotonic ρc( T) curves for GaAs contacts have been observed for the first time. The obtained experimental temperature dependences of ρc can be explained in the framework of the mechanism of current passage via metal shunts incorporated into semiconductor with allowance for electrons freezing out at liquid-helium temperatures. The ohmic character of contacts is ensured due to limitation of the electron current by diffusion supply in the presence of band bending at the semiconductor-metal interface near the shunt edge.

  10. Photoacoustic Spectroscopic Study of Optical Properties of hbox {Cu}2hbox {GeTe}3 in Temperature Range from 80 K to 300 K

    NASA Astrophysics Data System (ADS)

    Deviprasadh, P. S.; Madhuri, W.; Verma, A. S.; Sarkar, B. K.

    2016-05-01

    We used photoacoustic spectroscopy to investigate the optical properties of hbox {Cu}2hbox {GeTe}3. The temperature dependence of the bandgap energy was evaluated from optical absorption spectra obtained in the photon energy range of 0.76 eV to 0.81 eV between 80 K and 300 K. We used the empirical and semi-empirical models of Varshni, Viña, and Pässler to describe the observed bandgap shrinkage in this compound. The Debye temperature and effective phonon temperature of the compound were estimated to be approximately 227.4 K and 151.6 K, respectively. Thus, the temperature dependence of the bandgap is mediated by acoustic phonons.

  11. Characterization of 6H-SiC JFET Integrated Circuits Over A Broad Temperature Range from -150 C to +500 C

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Krasowski, Michael J.; Chen, Liang-Yu; Prokop, Norman F.

    2009-01-01

    The NASA Glenn Research Center has previously reported prolonged stable operation of simple prototype 6H-SiC JFET integrated circuits (logic gates and amplifier stages) for thousands of hours at +500 C. This paper experimentally investigates the ability of these 6H-SiC JFET devices and integrated circuits to also function at cold temperatures expected to arise in some envisioned applications. Prototype logic gate ICs experimentally demonstrated good functionality down to -125 C without changing circuit input voltages. Cascaded operation of gates at cold temperatures was verified by externally wiring gates together to form a 3-stage ring oscillator. While logic gate output voltages exhibited little change across the broad temperature range from -125 C to +500 C, the change in operating frequency and power consumption of these non-optimized logic gates as a function of temperature was much larger and tracked JFET channel conduction properties.

  12. Removal of formaldehyde by a pulsed dielectric barrier discharge in dry air in the 20 °C to 300 °C temperature range

    NASA Astrophysics Data System (ADS)

    Blin-Simiand, N.; Pasquiers, S.; Magne, L.

    2016-05-01

    The influence of the gas mixture temperature, from 20 °C up to 300 °C, on the removal of formaldehyde, diluted at low concentration (less than 800 ppm) in dry air at atmospheric pressure, by a pulsed dielectric barrier discharge (DBD) is studied by means of Fourier transform infrared spectroscopy and micro gas chromatography. Efficient removal of CH2O is obtained and it is found that the characteristic energy, less than 200 J l-1, is a decreasing function of the temperature over the whole range of concentration values under consideration. Byproducts issued from the removal are identified and quantified (CO, CO2, HCOOH, HNO3). Experimental results are analysed using a zero-dimensional simplified DBD-reactor model in order to gain insights on the chemical processes involved. It is shown that the dissociation of the molecule competes with oxidation reactions at low temperature, whereas at high temperature oxidation processes dominate.

  13. Experimental and theoretical study of the temperature and concentration dependence of the short-range order in Pt-V alloys

    NASA Astrophysics Data System (ADS)

    Le Bolloc'h, David; Caudron, René; Finel, Alphonse

    1998-02-01

    We present a detailed theoretical and experimental study of the short-range order in the Pt1-cVc system at two concentrations (c=14 and c=19). In situ neutron-scattering experiments were performed in order to measure the short-range-order parameters in the disordered phase. We found a drastic effect of the concentration on the short-range order: in Pt3V, the diffuse intensity is spread along the (1k0) directions with maxima at the (100) positions, despite the stability at low temperature of a DO22 phase. In contrast, the diffuse intensity in Pt8V displays a splitting around the (100) positions with incommensurate maxima. Through inverse Monte Carlo simulations the two experiments yield, within the Ising model, two sets of effective-pair interactions. Despite quite different short-range-order patterns, the interactions seem nearly concentration independent with a dominant first-neighbors interaction V1. This concentration independence allows us to predict the ordered states and the ordering temperatures. In particular, at low temperatures, these interactions stabilize a new phase of composition A5B, which to our knowledge has not been observed until now. Finally, we analyze the origin and behavior of the incommensurate split peaks in Pt8V within a high-temperature expansion and show analytically that the splitting is due to a large decrease of the influence of V1 on the short-range order as the concentration and/or the temperature decreases. This analysis shows also that the splitting distance should decrease with increasing temperature, in agreement with our Monte Carlo simulations, and in contrast with all the other alloys which have already been investigated, either experimentally or theoretically. More generally, we discuss the origin of the temperature behavior of a splitting distance in relation with the location in q space of the incommensurate maxima. Using very simple arguments, we show, provided the restriction that the first-neighbor interactions are

  14. A triarylmethyl spin label for long-range distance measurement at physiological temperatures using T1 relaxation enhancement

    NASA Astrophysics Data System (ADS)

    Yang, Zhongyu; Bridges, Michael D.; López, Carlos J.; Rogozhnikova, Olga Yu.; Trukhin, Dmitry V.; Brooks, Evan K.; Tormyshev, Victor; Halpern, Howard J.; Hubbell, Wayne L.

    2016-08-01

    Site-directed spin labeling (SDSL) in combination with electron paramagnetic resonance (EPR) spectroscopy has become an important tool for measuring distances in proteins on the order of a few nm. For this purpose pairs of spin labels, most commonly nitroxides, are site-selectively introduced into the protein. Recent efforts to develop new spin labels are focused on tailoring the intrinsic properties of the label to either extend the upper limit of measurable distances at physiological temperature, or to provide a unique spectral lineshape so that selective pairwise distances can be measured in a protein or complex containing multiple spin label species. Triarylmethyl (TAM) radicals are the foundation for a new class of spin labels that promise to provide both capabilities. Here we report a new methanethiosulfonate derivative of a TAM radical that reacts rapidly and selectively with an engineered cysteine residue to generate a TAM containing side chain (TAM1) in high yield. With a TAM1 residue and Cu2+ bound to an engineered Cu2+ binding site, enhanced T1 relaxation of TAM should enable measurement of interspin distances up to 50 Å at physiological temperature. To achieve favorable TAM1-labeled protein concentrations without aggregation, proteins are tethered to a solid support either site-selectively using an unnatural amino acid or via native lysine residues. The methodology is general and readily extendable to complex systems, including membrane proteins.

  15. Self-compliance Pt/HfO2/Ti/Si one-diode-one-resistor resistive random access memory device and its low temperature characteristics

    NASA Astrophysics Data System (ADS)

    Lu, Chao; Yu, Jue; Chi, Xiao-Wei; Lin, Guang-Yang; Lan, Xiao-Ling; Huang, Wei; Wang, Jian-Yuan; Xu, Jian-Fang; Wang, Chen; Li, Cheng; Chen, Song-Yan; Liu, Chunli; Lai, Hong-Kai

    2016-04-01

    A bipolar one-diode-one-resistor (1D1R) device with a Pt/HfO2/Ti/n-Si(001) structure was demonstrated. The 1D1R resistive random access memory (RRAM) device consists of a Ti/n-Si(001) diode and a Pt/HfO2/Ti resistive switching cell. By using the Ti layer as the shared electrode for both the diode and the resistive switching cell, the 1D1R device exhibits the property of stable self-compliance and the characteristic of robust resistive switching with high uniformity. The high/low resistance ratio reaches 103. The electrical RESET/SET curve does not deteriorate after 68 loops. Low-temperature studies show that the 1D1R RRAM device has a critical working temperature of 250 K, and at temperatures below 250 K, the device fails to switch its resistances.

  16. Triphenylene-Based Room-Temperature Discotic Liquid Crystals: A New Class of Blue-Light-Emitting Materials with Long-Range Columnar Self-Assembly.

    PubMed

    Gupta, Monika; Pal, Santanu Kumar

    2016-02-01

    A straightforward synthesis of multialkynylbenzene-bridged triphenylene-based dyad systems (via flexible alkyl spacers) that self-organize into room-temperature columnar structures over a long range is reported. The compounds with spacer lengths (n) of 8 and 10 exhibit a columnar rectangular mesophase whereas a compound with n = 6 shows a columnar rectangular plastic phase. Interestingly, the later compound (n = 6) shows the formation of well-nucleated spherulites of about several hundred micrometers that suggest the existence of a long-range uniform self-assembly of columns. All of these compounds show blue luminescence in solution and in the thin-film state under long-wavelength (365 nm) UV light. These compounds fulfill the described demands such as long-range columnar self-assembly at room temperature, a good yield with high purity, and blue-light emitters under the neat condition for possible potential applications in semiconductor devices. They also match the criteria of facile processing from the isotropic state because of their low isotropization temperature. This new class of materials is promising, considering the emissive nature and stabilization of the columnar mesophase at ambient temperature. PMID:26745267

  17. The thermodynamic properties of 5-vinyltetrazole and poly-5-vinyltetrazole over the temperature range from T → 0 to 350 K

    NASA Astrophysics Data System (ADS)

    Smirnova, N. N.; Kulagina, T. G.; Bykova, T. A.; Kizhnyaev, V. N.; Petrova, T. L.

    2009-01-01

    The temperature dependences of the heat capacities of 5-vinyltetrazole and poly-5-vinyltetrazole were measured by adiabatic vacuum calorimetry over the temperature range 6-(350-370) K with errors of ˜0.2%. The results were used to calculate the thermodynamic functions of the compounds, C {/p ∘}, H ∘( T) - H ∘(0), S ∘( T), and G ∘( T) - H ∘(0), over the temperature range from T → 0 to 350-370 K. The energy of combustion of 5-vinyltetrazole and poly-5-vinyltetrazole was measured in an isothermic-shell static bomb calorimeter. The standard enthalpies of combustion Δ c H ∘ and thermodynamic characteristics of formation Δf H ∘, Δf S ∘, and Δf G ∘ at 298.15 K and p = 0.1 MPa were calculated. The results were used to determine the thermodynamic characteristics of polymerization of 5-vinyltetrazole over the temperature range from T → 0 to 350 K.

  18. Room temperature photoluminescence in the visible range from silicon nanowires grown by a solid-state reaction

    NASA Astrophysics Data System (ADS)

    Anguita, J. V.; Sharma, P.; Henley, S. J.; Silva, S. R. P.

    2009-11-01

    The solid-liquid-solid method (also known as the solid-state method) is used to produce silicon nanowires at the core of silica nanowires with a support catalyst layer structure of nickel and titanium layers sputtered on oxide-coated silicon wafers. This silane-free process is low cost and large-area compatible. Using electron microscopy and Raman spectroscopy we deduce that the wires have crystalline silicon cores. The nanowires show photoluminescence in the visible range (orange), and we investigate the origin of this band. We further show that the nanowires form a random mesh that acts as an efficient optical trap, giving rise to an optically absorbing medium.

  19. Measurements of complex permittivity of microwave substrates in the 20 to 300 K temperature range from 26.5 to 40.0 GHz

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Gordon, William L.; Heinen, Vernon O.; Ebihara, Ben T.; Bhasin, Kul B.

    1990-01-01

    A knowledge of the dielectric properties of microwve substrates at low temperatures is useful in the design of superconducting microwave circuits. Results are reported for a study of the complex permittivity of sapphire (Al2O3), magnesium oxide (MgO), silicon oxide (SiO2), lanthanum aluminate (LaAlO3), and zirconium oxide (ZrO2), in the 20 to 300 Kelvin temperature range, at frequencies from 26.5 to 40.0 GHz. The values of the real and imaginary parts of the complex permittivity were obtained from the scattering parameters, which were measured using an HP-8510 automatic network analyzer. For these measurements, the samples were mounted on the cold head of a helium gas closed cycle refrigerator, in a specially designated vacuum chamber. An arrangement of wave guides, with mica windows, was used to connect the cooling system to the network analyzer. A decrease in the value of the real part of the complex permittivity of these substrates, with decreasing temperature, was observed. For MgO and Al2O3, the decrease from room temperature to 20 K was of 7 and 15 percent, respectively. For LaAlO3, it decreased by 14 percent, for ZrO2 by 15 percent, and for SiO2 by 2 percent, in the above mentioned temperature range.

  20. Measurements of complex permittivity of microwave substrates in the 20 to 300 K temperature range from 26.5 to 40.0 GHz

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Gordon, William L.; Heinen, Vernon O.; Ebihara, Ben T.; Bhasin, Kul B.

    1989-01-01

    A knowledge of the dielectric properties of microwave substrates at low temperatures is useful in the design of superconducting microwave circuits. Results are reported for a study of the complex permittivity of sapphire (Al2O3), magnesium oxide (MgO), silicon oxide (SiO2), lanthanum aluminate (LaAlO3), and zirconium oxide (ZrO2), in the 20 to 300 Kelvin temperature range, at frequencies from 26.5 to 40.0 GHz. The values of the real and imaginary parts of the complex permittivity were obtained from the scattering parameters, which were measured using a HP-8510 automatic network analyzer. For these measurements, the samples were mounted on the cold head of a helium gas closed cycle refrigerator, in a specially designed vacuum chamber. An arrangement of wave guides, with mica windows, was used to connect the cooling system to the network analyzer. A decrease in the value of the real part of the complex permittivity of these substrates, with decreasing temperature, was observed. For MgO and Al2O3, the decrease from room temperature to 20 K was of 7 and 15 percent, respectively. For LaAlO3, it decreased by 14 percent, for ZrO2 by 15 percent, and for SiO2 by 2 percent, in the above mentioned temperature range.

  1. Thermal degradation of concrete in the temperature range from ambient to 315{degree} C (600{degree} F). Revision 10/96

    SciTech Connect

    Kassir, M.K.; Bandyopadhyay, K.K.; Reich, M.

    1996-10-01

    This report is concerned with determining the effect of elevated temperatures on the behavior of concrete. Emphasis is placed on quantifying the degree of potential degradation of the physical properties of concrete in high-level waste storage tanks. The temperature elevation range of interest is from ambient to 315 C (600 F). The literature has been reviewed to examine the applicable experimental data and quantify the degradation in the concrete and reinforcing steel. Since many variables and test conditions control the results in the data base, upper and lower bounds of the degraded properties at temperatures applicable to the environments of the storage tanks are summarized and presented in explicit forms. For properties with large data bases, a normal logarithmic distribution of the data is assumed and a statistical analysis is carried out to find the mean and 84% values of the degraded property in the temperature range of interest. Such results are useful in assessing the effect of elevated temperatures on the structural behavior of the tanks. In addition, the results provide the technical basis for a parametric study that may be necessary to investigate the thermal aspects of the structural integrity of the tanks. 50 refs., 23 figs.

  2. An apparatus for simultaneous measurement of electrical conductivity and thermopower of thin films in the temperature range of 300-750 K

    SciTech Connect

    Ravichandran, J.; Kardel, J. T.; Scullin, M. L.; Bahk, J.-H.; Bowers, J. E.; Heijmerikx, H.; Majumdar, A.

    2011-01-15

    An automated apparatus capable of measuring the electrical conductivity and thermopower of thin films over a temperature range of 300-750 K is reported. A standard dc resistance measurement in van der Pauw geometry was used to evaluate the electrical conductivity, and the thermopower was measured using the differential method. The design of the instrument, the methods used for calibration, and the measurement procedure are described in detail. Given the lack of a standard National Institute of Standards and Technology (Gaithersburg, Md.) sample for high temperature thermopower calibration, the disclosed calibration procedure shall be useful for calibration of new instruments.

  3. An apparatus for simultaneous measurement of electrical conductivity and thermopower of thin films in the temperature range of 300-750 K.

    PubMed

    Ravichandran, J; Kardel, J T; Scullin, M L; Bahk, J-H; Heijmerikx, H; Bowers, J E; Majumdar, A

    2011-01-01

    An automated apparatus capable of measuring the electrical conductivity and thermopower of thin films over a temperature range of 300-750 K is reported. A standard dc resistance measurement in van der Pauw geometry was used to evaluate the electrical conductivity, and the thermopower was measured using the differential method. The design of the instrument, the methods used for calibration, and the measurement procedure are described in detail. Given the lack of a standard National Institute of Standards and Technology (Gaithersburg, Md.) sample for high temperature thermopower calibration, the disclosed calibration procedure shall be useful for calibration of new instruments.

  4. Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

    SciTech Connect

    Curry, J. J.; Henins, A.; Hardis, J. E.; Estupinan, E. G.; Lapatovich, W. P.; Shastri, S. D.

    2012-02-20

    Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

  5. Thermal expansion and phase changes of 16Kh12V2FTaR steel in temperature range from 20 to 1000 °C

    NASA Astrophysics Data System (ADS)

    Kozlovskii, Yu. M.; Stankus, S. V.; Yatsuk, O. S.; Agazhanov, A. Sh.; Komarov, S. G.; Anufriyev, I. S.

    2014-01-01

    The article presents the results of investigation of thermal expansion of 16Kh12V2FTaR steel in the temperature range 20-1000 °C. Measurements were carried out by dilatometric method with the error (1.5-2)×10-7 K-1. The temperature dependences of thermal coefficient of linear expansion of steel have been obtained in ferrite-martensite and ferrite-perlite states, and reference tables have been calculated. Influence of samples cooling rate on martensite phase formation is shown.

  6. Talc friction in the temperature range 25°–400 °C: relevance for fault-zone weakening

    USGS Publications Warehouse

    Moore, Diane E.; Lockner, David A.

    2008-01-01

    Talc has a temperature–pressure range of stability that extends from surficial to eclogite-facies conditions, making it of potential significance in a variety of faulting environments. Talc has been identified in exhumed subduction zone thrusts, in fault gouge collected from oceanic transform and detachment faults associated with rift systems, and recently in serpentinite from the central creeping section of the San Andreas fault. Typically, talc crystallized in the active fault zones as a result of the reaction of ultramafic rocks with silica-saturated hydrothermal fluids. This mode of formation of talc is a prime example of a fault-zone weakening process. Because of its velocity-strengthening behavior, talc may play a role in stabilizing slip at depth in subduction zones and in the creeping faults of central and northern California that are associated with ophiolitic rocks.

  7. Precipitation and winter temperature predict long-term range-scale abundance changes in Western North American birds.

    PubMed

    Illán, Javier Gutiérrez; Thomas, Chris D; Jones, Julia A; Wong, Weng-Keen; Shirley, Susan M; Betts, Matthew G

    2014-11-01

    Predicting biodiversity responses to climate change remains a difficult challenge, especially in climatically complex regions where precipitation is a limiting factor. Though statistical climatic envelope models are frequently used to project future scenarios for species distributions under climate change, these models are rarely tested using empirical data. We used long-term data on bird distributions and abundance covering five states in the western US and in the Canadian province of British Columbia to test the capacity of statistical models to predict temporal changes in bird populations over a 32-year period. Using boosted regression trees, we built presence-absence and abundance models that related the presence and abundance of 132 bird species to spatial variation in climatic conditions. Presence/absence models built using 1970-1974 data forecast the distributions of the majority of species in the later time period, 1998-2002 (mean AUC = 0.79 ± 0.01). Hindcast models performed equivalently (mean AUC = 0.82 ± 0.01). Correlations between observed and predicted abundances were also statistically significant for most species (forecast mean Spearman's ρ = 0.34 ± 0.02, hindcast = 0.39 ± 0.02). The most stringent test is to test predicted changes in geographic patterns through time. Observed changes in abundance patterns were significantly positively correlated with those predicted for 59% of species (mean Spearman's ρ = 0.28 ± 0.02, across all species). Three precipitation variables (for the wettest month, breeding season, and driest month) and minimum temperature of the coldest month were the most important predictors of bird distributions and abundances in this region, and hence of abundance changes through time. Our results suggest that models describing associations between climatic variables and abundance patterns can predict changes through time for some species, and that changes in precipitation and winter temperature appear to

  8. Precipitation and winter temperature predict long-term range-scale abundance changes in Western North American birds.

    PubMed

    Illán, Javier Gutiérrez; Thomas, Chris D; Jones, Julia A; Wong, Weng-Keen; Shirley, Susan M; Betts, Matthew G

    2014-11-01

    Predicting biodiversity responses to climate change remains a difficult challenge, especially in climatically complex regions where precipitation is a limiting factor. Though statistical climatic envelope models are frequently used to project future scenarios for species distributions under climate change, these models are rarely tested using empirical data. We used long-term data on bird distributions and abundance covering five states in the western US and in the Canadian province of British Columbia to test the capacity of statistical models to predict temporal changes in bird populations over a 32-year period. Using boosted regression trees, we built presence-absence and abundance models that related the presence and abundance of 132 bird species to spatial variation in climatic conditions. Presence/absence models built using 1970-1974 data forecast the distributions of the majority of species in the later time period, 1998-2002 (mean AUC = 0.79 ± 0.01). Hindcast models performed equivalently (mean AUC = 0.82 ± 0.01). Correlations between observed and predicted abundances were also statistically significant for most species (forecast mean Spearman's ρ = 0.34 ± 0.02, hindcast = 0.39 ± 0.02). The most stringent test is to test predicted changes in geographic patterns through time. Observed changes in abundance patterns were significantly positively correlated with those predicted for 59% of species (mean Spearman's ρ = 0.28 ± 0.02, across all species). Three precipitation variables (for the wettest month, breeding season, and driest month) and minimum temperature of the coldest month were the most important predictors of bird distributions and abundances in this region, and hence of abundance changes through time. Our results suggest that models describing associations between climatic variables and abundance patterns can predict changes through time for some species, and that changes in precipitation and winter temperature appear to

  9. Direct Electron Heating Observed by Fast Waves in ICRF Range on a Low-Density Low Temperature Tokamak ADITYA

    SciTech Connect

    Mishra, K.; Kulkarni, S.; Rathi, D.; Varia, A.; Jadav, H.; Parmar, K.; Kadia, B.; Joshi, R.; Srinivas, Y.; Singh, R.; Kumar, S.; Dani, S.; Gayatri, A.; Yogi, R.; Singh, M.; Joisa, Y.; Rao, C.; Kumar, S.; Jha, R.; Manchanda, R.

    2011-12-23

    Fast wave electron heating experiments are carried out on Aditya tokamak [R = 0.75 m, a = 0.25m,Bt = 0.75T,ne{approx}1-3E13/cc,Te{approx}250eV] with the help of indigenously developed 200 kW, 20-40 MHz RF heating system. Significant direct electron heating is observed by fast waves in hydrogen plasma with prompt rise in electron temperature with application of RF power and it increases linearly with RF power. A corresponding increase in plasma beta and hence increase in stored diamagnetic energy is also observed in presence of RF. We observe an improvement of energy confinement time from 2-4msec during ohmic heating phase to 3-6msec in RF heating phase. This improvement is within the ohmic confinement regime for the present experiments. The impurity radiation and electron density do not escalate significantly with RF power. The direct electron heating by fast wave in Aditya is also predicted by ion cyclotron resonance heating code TORIC.

  10. Kinetic investigation of the reactions of NCO radicals with alkanes in the temperature range 294 to 1,113 K

    SciTech Connect

    Schuck, A.; Volpp, H.R.; Wolfrum, J. . Physikalisch-Chemisches Inst.)

    1994-12-01

    Absolute rate coefficients for the reaction of NCO radicals with methane (k[sub 1]), ethane (k[sub 2]), and propane (k[sub 3]) were measured as a function of temperature in a heatable quartz reactor by means of the laser photolysis/laser-induced fluorescence (LP/LIF) pump-probe technique. NCO radicals were produced by the fast precursor reaction NH(a[sup 1] [Delta]) + HNCO [yields] NH[sub 2] + NCO, following the 193-nm photolysis of isocyanic acid. The measure rate coefficients can be described by the following expressions: k[sub 1](512 < T < 1,113 K) = 10[sup 12.99 [+-] 0.12] [times] exp(-34.0[+-]1.8 kJ/mol/RT) cm[sup 3]/mol s; k[sub 2](296 < T < 922 K) = 10[sup 8.21] [times] (T/298 K)[sup (6.89[+-]0.02)] [times] exp(12.2[+-]0.5 kJ/mol/RT)cm[sup 3]/mol s; and k[sub 3](300 < T < 849 K) = 10[sup 11.49] [times] (T/298 K)[sup (2.15[+-]0.02)] [times] exp(-1.8[+-]0.4 kJ/mol/RT)cm[sup 3]/mol s. A comparison with the corresponding reactions of CN, Cl, and OH radicals with alkanes suggests that all these title reactions also proceed predominantly via a hydrogen atom abstraction mechanism to form HNCO.

  11. Spectral emissivity modeling of steel 201 during the growth of oxidation film over the temperature range from 800 to 1100 K in air

    NASA Astrophysics Data System (ADS)

    Shi, Deheng; Zou, Fenghui; Wang, Shuai; Zhu, Zunlue; Sun, Jinfeng; Wang, Baokui

    2014-11-01

    This study explores the spectral emissivity modeling of steel 201 during the growth of oxidation film over the temperature range from 800 to 1100 K at 1.5 μm. The radiance coming from the specimen is received by an InGaAs photodiode detector. The specimen temperature is obtained by averaging the two platinum-rhodium thermocouples, which are tightly welded in the front surface of specimen near the measuring area viewed by the detector. The variation of spectral emissivity with the temperature is studied at a given heating time. The variation of spectral emissivity with the heating time is evaluated at a definite temperature. The strong oscillations of spectral emissivity are observed and discussed in detail, which originate from the interference effect between the radiation stemming from the oxidization film on the specimen surface and the radiation coming from the specimen surface. The measurement uncertainties of spectral emissivity contributed only by the surface oxidization are about 3.2-14.1%. At a given heating time, the variation of spectral emissivity with the temperature abides well by a simple analytic functional form. And at a definite temperature, the variation of spectral emissivity with the heating time can also be well reproduced by fitting except for the periodical oscillations.

  12. Validation of a rotational coherent anti-Stokes Raman spectroscopy model for carbon dioxide using high-resolution detection in the temperature range 294-1143 K

    NASA Astrophysics Data System (ADS)

    Vestin, Fredrik; Nilsson, Kristin; Bengtsson, Per-Erik

    2008-04-01

    Experiments were performed in the temperature range of 294-1143 K in pure CO2 using high-resolution rotational coherent anti-Stokes Raman spectroscopy (CARS), in the dual-broadband approach. Experimental single-shot spectra were recorded with high spectral resolution using a single-mode Nd:YAG laser and a relay imaging lens system on the exit of a 1 m spectrometer. A theoretical rotational CARS model for CO2 was developed for evaluation of the experimental spectra. The evaluated mean temperatures of the recorded single-shot dual-broadband rotational coherent anti-Stokes Raman spectroscopy (DB-RCARS) spectra using this model showed good agreement with thermocouple temperatures, and the relative standard deviation of evaluated single-shot temperatures was generally 2-3%. Simultaneous thermometry and relative CO2/N2-concentration measurements were demonstrated in the product gas of premixed laminar CO/air flames at atmospheric pressure. Although the model proved to be accurate for thermometry up to 1143 K, limitations were observed at flame temperatures where temperatures were overestimated and relative CO2/N2 concentrations were underestimated. Potential sources for these discrepancies are discussed.

  13. Operation of a New Half-Bridge Gate Driver for Enhancement - Mode GaN FETs, Type LM5113, Over a Wide Temperature Range

    NASA Technical Reports Server (NTRS)

    Patterson, Richard; Hammoud, Ahmad

    2011-01-01

    A new commercial-off-the-shelf (COTS) gate driver designed to drive both the high-side and the low-side enhancement-mode GaN FETs, National Semiconductor's type LM5113, was evaluated for operation at temperatures beyond its recommended specified limits of -40 C to +125 C. The effects of limited thermal cycling under the extended test temperature, which ranged from -194 C to +150 C, on the operation of this chip as well as restart capability at the extreme cryogenic and hot temperatures were also investigated. The driver circuit was able to maintain good operation throughout the entire test regime between -194 C and +150 C without undergoing any major changes in its outputs signals and characteristics. The limited thermal cycling performed on the device also had no effect on its performance, and the driver chip was able to successfully restart at each of the extreme temperatures of -194 C and +150 C. The plastic packaging of this device was also not affected by either the short extreme temperature exposure or the limited thermal cycling. These preliminary results indicate that this new commercial-off-the-shelf (COTS) halfbridge eGaN FET driver integrated circuit has the potential for use in space exploration missions under extreme temperature environments. Further testing is planned under long-term cycling to assess the reliability of these parts and to determine their suitability for extended use in the harsh environments of space.

  14. Giant elastocaloric effect covering wide temperature range in columnar-grained Cu71.5Al17.5Mn11 shape memory alloy

    NASA Astrophysics Data System (ADS)

    Xu, Sheng; Huang, Hai-You; Xie, Jianxin; Takekawa, Shouhei; Xu, Xiao; Omori, Toshihiro; Kainuma, Ryosuke

    2016-10-01

    The elastocaloric effect in a columnar-grained Cu71.5Al17.5Mn11 shape memory alloy fabricated by directional solidification was investigated. A large entropy change of 25.0 J/kg K generated by the reversible martensitic transformation was demonstrated. The adiabatic temperature change of 12-13 K was directly measured, covering a wide temperature range of more than 100 K. The low applied stress with a specific elastocaloric ability of 100.8 K/GPa was identified and the potentially attainable operational temperature window as wide as more than 215 K was also discussed. The outstanding elastocaloric refrigeration capability, together with the low applying stress and uniform phase transformation, makes the columnar-grained Cu-Al-Mn shape memory alloy a promising material for solid-state refrigeration.

  15. On the low-temperature behavior of the critical specific heat capacity of an anharmonic crystal with long-range interaction

    NASA Astrophysics Data System (ADS)

    Pisanova, Ekaterina S.; Krushkov, Angel Y.

    2016-03-01

    An exactly solvable lattice model describing structural phase transitions in an anharmonic crystal with long-range interaction (decreasing at large distances r as r-d-σ, where d is the space dimensionality and 0 < σ ≤ 2) is considered near to its zero-temperature critical point. The low-temperature behavior of the bulk specific heat capacity at the lower classical critical dimension (d = σ) is studied in different regions of the (T, λ)-phase diagram, where T is the temperature and λ is a parameter which switches on quantum fluctuations. From the results obtained one can see that when T → 0+ the specific heat capacity tends to zero in a different way in the regions: (a) renormalized classical region - as T raised to the second power and (b) quantum disordered region - exponentially.

  16. Application of the methane saturated dispersion resonance near 2.36 μm over the temperature range of 77-300 K for optical frequency standards

    NASA Astrophysics Data System (ADS)

    Tarabrin, Mikhail K.; Lazarev, Vladimir A.; Karasik, Valeriy E.; Kireev, Alexey N.; Korostelin, Yuri V.; Shelkovnikov, Alexander S.; Tuyrikov, Dmitry A.; Kozlovsky, Vladimir I.; Podmar'kov, Yuri P.; Frolov, Mikhail P.; Gubin, Mikhail A.

    2016-07-01

    New spectroscopic knowledge of the ν1 +ν4 R(2) E line of methane over the temperature range 77-300 K is reported. Theoretical calculations of the absorption coefficient and the amplitudes of saturated dispersion resonances at 4234 cm-1 were derived. The theoretical dependence on the temperature of the amplitudes of the saturated dispersion resonances was obtained. A novel setup based on a Cr2+ : ZnSe laser was used for Doppler-free spectroscopy of methane. The amplitudes of the saturated dispersion resonances of the ν1 +ν4 R(2) E line of methane were measured experimentally at different temperatures. A comparison with theoretical dependence supports the reliability of the experiment. The obtained results are of immediate interest in applications demanding laser frequency stabilization.

  17. Broad temperature range of cubic blue phase present in simple binary mixture systems containing rodlike Schiff base mesogens with tolane moiety.

    PubMed

    Huang, Chiung-Cheng; Chen, Yu-Hao; Chen, Sheng-Yen; Sun, Yi-Zeng; Wu, Zong-Ye; Yu, Mei-Ching; Chen, Bo-Hao; Hsu, I-Jui; Wu, Lai-Chin; Lee, Jey-Jau

    2016-03-28

    Four simple rodlike Schiff base mesogens with tolane moiety were synthesized and applied to stabilize cubic blue phases (BPs) in simple binary mixture systems for the first time. When the chiral additive or was added into a chiral salicylaldimine-based compound, the temperature range of the cubic BP could be extended by more than 20 °C. However, when the chiral Schiff base mesogen was blended with chiral dopant possessing opposite handedness, , BPs could not be observed. Interestingly, the widest temperature range of the cubic BPs (∼35 °C) could be induced by adding the rodlike chiral dopant or into the rodlike racemic Schiff base mesogen with hydroxyl group. On the basis of our experimental results and molecular modeling, the appearance and temperature range of the BPs are affected by the dipole moment and the biaxiality of the molecular geometry. Accordingly, we demonstrated that the hydroxyl group and the methyl branch in this type of Schiff base mesogen play an important role in the stabilization of BPs.

  18. Characterization and potential of three temperature ranges for hydrogen fermentation of cellulose by means of activity test and 16s rRNA sequence analysis.

    PubMed

    Gadow, Samir I; Jiang, Hongyu; Li, Yu-You

    2016-06-01

    A series of standardized activity experiments were performed to characterize three different temperature ranges of hydrogen fermentation from different carbon sources. 16S rRNA sequences analysis showed that the bacteria were close to Enterobacter genus in the mesophilic mixed culture (MMC) and Thermoanaerobacterium genus in the thermophilic and hyper-thermophilic mixed cultures (TMC and HMC). The MMC was able to utilize the glucose and cellulose to produce methane gas within a temperature range between 25 and 45 °C and hydrogen gas from 35 to 60°C. While, the TMC and HMC produced only hydrogen gas at all temperature ranges and the highest activity of 521.4mlH2/gVSSd was obtained by TMC. The thermodynamic analysis showed that more energy is consumed by hydrogen production from cellulose than from glucose. The experimental results could help to improve the economic feasibility of cellulosic biomass energy using three-phase technology to produce hythane.

  19. The response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress

    NASA Astrophysics Data System (ADS)

    Holmquist, T. J.; Bradley, J.; Dwivedi, A.; Casem, D.

    2016-05-01

    This article presents the response of polymethyl methacrylate (PMMA) subjected to large strains, high strain rates, high pressures, a range in temperatures, and variations in the intermediate principal stress. Laboratory data from the literature, and new test data provided here, are used in the evaluation. The new data include uniaxial stress compression tests (at various strain rates and temperatures) and uniaxial stress tension tests (at low strain rates and ambient temperatures). The compression tests include experiments at ˙ɛ = 13,000 s-1, significantly extending the range of known strain rate data. The observed behavior of PMMA includes the following: it is brittle in compression at high rates, and brittle in tension at all rates; strength is dependent on the pressure, strain, strain rate, temperature, and the intermediate principal stress; the shear modulus increases as the pressure increases; and it is highly compressible. Also presented are novel, high velocity impact tests (using high-speed imaging) that provide insight into the initiation and evolution of damage. Lastly, computational constitutive models for pressure, strength, and failure are presented that provide responses that are in good agreement with the laboratory data. The models are used to compute several ballistic impact events for which experimental data are available.

  20. Magnetic susceptibility of (Bi{sub 2-x}Sb{sub x})Te{sub 3} (0 < x < 1) alloys in the temperature range 2 to 50 K

    SciTech Connect

    Stepanov, N. P.; Nalivkin, V. U.; Potapov, G. A.

    2012-01-15

    The superconducting quantum interferometer device with Josephson junctions (SQUID magnetometer) is used to study the temperature dependences of the magnetic susceptibility of (Bi{sub 2-x}Sb{sub x})Te{sub 3} (0 < x < 1) alloy crystals in the temperature range 2 to 50 K, at the magnetic field vector H orientations H perpendiular C{sub 3} and H Up-Tack C{sub 3} with respect to the crystal trigonal axis C{sub 3}. It is found that the magnetic susceptibility of the ion core of the samples under study is {chi}{sup G} = -0.35 Multiplication-Sign 10{sup -6} cm{sup 3}/g, the contribution of lattice defects to magnetic susceptibility can be disregarded, and the contribution of free carriers is of a diamagnetic nature in the entire studied temperature range. It is shown that the contribution of free carriers to the resulting magnetic susceptibility and its anisotropy can be described within the Pauli and Landau-Peierls approach. In calculating the magnetic susceptibility, taking into account the constant concentration of free carriers in the state of pronounced degeneracy, it is found that the temperature dependence of the anisotropic effective masses varies with crystal chemical composition. This is possibly associated with the complex structure of the valence band and its variation as the Sb{sub 2}Te{sub 3} content in the alloy increases.

  1. Study of the dielectric properties of weathered granite, basalt and quartzite by means of broadband dielectric spectroscopy over a wide range of frequency and temperature.

    NASA Astrophysics Data System (ADS)

    Araujo, Steven; Delbreilh, Laurent; Antoine, Raphael; Dargent, Eric; Fauchard, Cyrille

    2016-04-01

    Broadband Dielectric Spectroscopy (BDS) allows the measurement of the complex impedance of various materials over a wide range of frequency (0.1 Hz to 2 MHz) and temperature (-150 to 400°C). Other properties can be assessed from this measurement such as permittivity and conductivity. In this study, the BDS is presented to figure out the complex behaviour of several rock parameters as a function of the temperature and frequency. Indeed, multiple processes might occur such as interfacial polarization, AC and DC conductivity. The measurements of a weathered granite, basalt and quartzite were performed. The activation energy associated to each process involved during the measurement can be calculated by following the relaxation time as a function of the temperature, taking into account the Havriliak-Négami model. The principle of the technique and the whole study is presented here and several hypothesis are advanced to explain the dielectric behaviour of rocks. Finally, as the range of frequency and temperature of the BDS method is common to several electromagnetic and electrical techniques applied in subsurface geophysics, some perspectives are proposed to better understand geophysical measurements in hydrothermal systems.

  2. Influence of CO molecular impurity on the structural and thermodynamic properties of fullerite C60, in a broad range of sorption temperatures

    NASA Astrophysics Data System (ADS)

    Meleshko, V. V.; Legchenkova, I. V.; Stetsenko, Y. E.; Prokhvatilov, A. I.

    2016-02-01

    An x-ray diffraction study of how sorption of CO gas at a pressure of 30 atm in the temperature range of 150-600 °C influences the structural characteristics of polycrystalline and single crystal fullerite C60. The sorption kinetics are studied by constructing a dependence of the lattice parameter on the time it takes for fullerite to be saturated by CO molecules. At temperatures Tsorb > 300 °C there is an observed dissociation of carbon monoxide, accompanied by the precipitation of carbon powder and the chemical interaction of atomic oxygen with C60 and CO molecules, and possibly with the carbon condensate. These processes have a strong influence on the structural characteristics of fullerite, thus creating, in part, a nonmonotonic dependence of the parameter and lattice matrix volume on the impurity saturation temperature. The concentrations of solid solutions C60(CO)x poly- and single crystal samples are determined in the physisorption range for two modes (150 and 250 °C). It is found that the CO impurity has a linear effect on the lattice parameter and the temperature of the orientational transition of fullerite C60.

  3. A new method to calculate the threshold temperature of a perfect blackbody to protect cornea and lens in the range of 780-3,000 nm.

    PubMed

    Madjidi, Faramarz; Mohammadi, Jamshid

    2015-01-01

    Exposure to IR-A and IR-B radiation, in the wavelength region of 780 nm to 3,000 nm, may lead to the development of cataractogenesis. Estimation of the exposure levels is the first step in controlling adverse health effects. In the present study, the irradiance of a hot blackbody emitter is replaced by its temperature in the exposure limit values for cornea and lens in the range of 780-3,000 nm. This paper explains the development and implementation of a computer code to predict a temperature, defined as Threshold Temperature, which satisfies the exposure limits already proposed by the ICNIRP. To this end, first an infinite series was created for the calculation of spectral radiance by integration with Planck's law. For calculation of irradiance, the initial terms of this infinite series were selected, and integration was performed in the wavelength region of 780 nm to 3,000 nm. Finally, using a computer code, an unknown source temperature that can emit the same irradiance was found. Exposure duration, source area, and observer distance from the hot source were entered as input data in this proposed code. Consequently, it is possible only by measurement of a Planckian emitter temperature and taking into account the distance from source and exposure time for an observer to decide whether the exposure to IR radiation in the range of 780 to 3,000 nm is permissible or not. It seems that the substitution of irradiance by the source temperature is an easier and more convenient way for hygienists to evaluate IR exposures. PMID:25437515

  4. Operating a triple stack microchannel plate-phosphor assembly for single particle counting in the 12-300 K temperature range.

    PubMed

    Rosén, Stefan; Schmidt, Henning T; Reinhed, Peter; Fischer, Daniel; Thomas, Richard D; Cederquist, Henrik; Liljeby, Leif; Bagge, Lars; Leontein, Sven; Blom, Mikael

    2007-11-01

    An assembly consisting of a stack of three microchannel plates (MCPs) and a phosphor screen anode has been operated over the temperature range from 300 to 12 K. We report on measurements at 6.4 kHz (using an alpha source) and with dark counts only (15 Hz). Without any particle source, the MCP bias current decreased by a factor of 2.1 x 10(3) when the temperature was lowered from 300 to 12 K. Using the alpha source, and a photomultiplier tube (PMT) to monitor the phosphor screen anode, we first observed an increase in the decay time of the phosphor from 12 to 45 mus when the temperature was decreased from 300 to 100 K while the decay time then decreased and reached a value of 5 mus at 12 K. The pulse height distribution from the PMT was measured between 300 and 12 K and shows a spectrum typical for a MCP phosphor setup at 300 K and 12 K but is strongly degraded for intermediate temperatures. We conclude that the present MCP-phosphor detector assembly is well suited for position-sensitive particle counting operation at temperatures down to at least 12 K even for count rates beyond 6 kHz. This result is crucial and an important part of ongoing developments of new instrumentation for investigations of, e.g., interactions involving complex molecular ions with internal quantum state control.

  5. Relationship between peak spatial-averaged specific absorption rate and peak temperature elevation in human head in frequency range of 1-30 GHz

    NASA Astrophysics Data System (ADS)

    Morimoto, Ryota; Laakso, Ilkka; De Santis, Valerio; Hirata, Akimasa

    2016-07-01

    This study investigates the relationship between the peak temperature elevation and the peak specific absorption rate (SAR) averaged over 10 g of tissue in human head models in the frequency range of 1-30 GHz. As a wave source, a half-wave dipole antenna resonant at the respective frequencies is located in the proximity of the pinna. The bioheat equation is used to evaluate the temperature elevation by employing the SAR, which is computed by electromagnetic analysis, as a heat source. The computed SAR is post-processed by calculating the peak spatial-averaged SAR with six averaging algorithms that consider different descriptions provided in international guidelines and standards, e.g. the number of tissues allowed in the averaging volume, different averaging shapes, and the consideration of the pinna. The computational results show that the SAR averaging algorithms excluding the pinna are essential when correlating the peak temperature elevation in the head excluding the pinna. In the averaging scheme considering an arbitrary shape, for better correlation, multiple tissues should be included in the averaging volume rather than a single tissue. For frequencies higher than 3-4 GHz, the correlation for peak temperature elevation in the head excluding the pinna is modest for the different algorithms. The 95th percentile value of the heating factor as well as the mean and median values derived here would be helpful for estimating the possible temperature elevation in the head.

  6. Relationship between peak spatial-averaged specific absorption rate and peak temperature elevation in human head in frequency range of 1–30 GHz

    NASA Astrophysics Data System (ADS)

    Morimoto, Ryota; Laakso, Ilkka; De Santis, Valerio; Hirata, Akimasa

    2016-07-01

    This study investigates the relationship between the peak temperature elevation and the peak specific absorption rate (SAR) averaged over 10 g of tissue in human head models in the frequency range of 1–30 GHz. As a wave source, a half-wave dipole antenna resonant at the respective frequencies is located in the proximity of the pinna. The bioheat equation is used to evaluate the temperature elevation by employing the SAR, which is computed by electromagnetic analysis, as a heat source. The computed SAR is post-processed by calculating the peak spatial-averaged SAR with six averaging algorithms that consider different descriptions provided in international guidelines and standards, e.g. the number of tissues allowed in the averaging volume, different averaging shapes, and the consideration of the pinna. The computational results show that the SAR averaging algorithms excluding the pinna are essential when correlating the peak temperature elevation in the head excluding the pinna. In the averaging scheme considering an arbitrary shape, for better correlation, multiple tissues should be included in the averaging volume rather than a single tissue. For frequencies higher than 3–4 GHz, the correlation for peak temperature elevation in the head excluding the pinna is modest for the different algorithms. The 95th percentile value of the heating factor as well as the mean and median values derived here would be helpful for estimating the possible temperature elevation in the head.

  7. The effect of a diet containing grasshoppers and access to free-range on carcase and meat physicochemical and sensory characteristics in broilers.

    PubMed

    Sun, T; Long, R J; Liu, Z Y

    2013-01-01

    1. Research was conducted to evaluate the impact of a diet containing grasshoppers on the carcase, physicochemical and sensory characteristics in a free-range, grassland-based broiler production system. 2. A total of 80, 28-d-old male broilers were reared on grassland containing a large population of grasshoppers (treatment PB). Control birds were reared intensively on a maize-soybean diet (treatment CB). At 91 d of age, 24 birds from each treatment were slaughtered to evaluate carcase, meat and sensory characteristics. 3. Treatment PB produced birds with significantly lower live weights, breast, wing, thigh and drum weights, and higher dressing percentage and breast percentage of carcase, compared with CB. Treatment PB produced breast meat with significantly higher redness values, shear force and protein content, and lower pH values, cooking loss, moisture and fat content compared with CB. Sensory panel results for breast and thigh meats showed no treatment effect on colour and juiciness, but significantly higher scores for chewiness, flavour, aroma and overall appreciation, and lower scores for tenderness from treatment PB compared with CB. 4. Rearing chickens on rangeland may provide an alternative way to produce poultry meat which is considered superior by modern consumers.

  8. GREENER AND RAPID ACCESS TO BIO-ACTIVE HETEROCYCLES: ROOM TEMPERATURE SYNTHESIS OF PYRAZOLES AND DIAZEPINES IN AQUEOUS MEDIUM

    EPA Science Inventory

    An expeditious room temperature synthesis of pyrazoles and diazepines by condensation of hydrazines/hydrazides and diamines with various 1,3-diketones is described. This greener protocol was catalyzed by polystyrene supported sulfonic acid (PSSA) and proceeded efficiently in wate...

  9. Northern range expansion of European populations of the wasp spider Argiope bruennichi is associated with global warming-correlated genetic admixture and population-specific temperature adaptations.

    PubMed

    Krehenwinkel, Henrik; Tautz, Diethard

    2013-04-01

    Poleward range expansions are observed for an increasing number of species, which may be an effect of global warming during the past decades. However, it is still not clear in how far these expansions reflect simple geographical shifts of species ranges, or whether new genetic adaptations play a role as well. Here, we analyse the expansion of the wasp spider Argiope bruennichi into Northern Europe during the last century. We have used a range-wide sampling of contemporary populations and historical specimens from museums to trace the phylogeography and genetic changes associated with the range shift. Based on the analysis of mitochondrial, microsatellite and SNP markers, we observe a higher level of genetic diversity in the expanding populations, apparently due to admixture of formerly isolated lineages. Using reciprocal transplant experiments for testing overwintering tolerance, as well as temperature preference and tolerance tests in the laboratory, we find that the invading spiders have possibly shifted their temperature niche. This may be a key adaptation for survival in Northern latitudes. The museum samples allow a reconstruction of the invasion's genetic history. A first, small-scale range shift started around 1930, in parallel with the onset of global warming. A more massive invasion of Northern Europe associated with genetic admixture and morphological changes occurred in later decades. We suggest that the latter range expansion into far Northern latitudes may be a consequence of the admixture that provided the genetic material for adaptations to new environmental regimes. Hence, global warming could have facilitated the initial admixture of populations and this resulted in genetic lineages with new habitat preferences.

  10. Analysis of model-calculated soil moisture over the United States (1931-1993) and applications to long-range temperature forecasts

    SciTech Connect

    Huang, J.; Dool, H.M. van den; Georgakakos, K.P.

    1996-06-01

    A long time series of monthly soil data during the period of 1931-1993 over the entire U.S. continent has been created with a one-layer soil moisture model. The model is based on the water budget in the soil and uses monthly temperature and monthly precipitation as input. The data are for 344 U.S. climate divisions during the period of 1931-1993. The maIn goals of this paper are (1) to improve our understanding of soil moisture and its effects on the atmosphere and (2) to apply the calculated soil moisture toward long-range temperature forecasts. In this study, the model parameters are estimated using observed precipitation, temperature, and runoff in Oklahoma (1960-1989) and applied to the entire United States. The comparison with the 8-yr (1984-1991) observed soil moisture in Illinois indicates that the model gives a reasonable simulation of soil moisture with both climatology and interannual variability. The analyses of the calculated soil moisture show that the climatological soil moisture is high in the east and low in the west (except the West Coast), which is determined by the climatological precipitation amounts. The annual cycle of soil moisture, however, is determined largely by evaporation. Authors found that generally in the U.S. evaporation anomalies are much smaller in magnitude than precipitation anomalies. Furthermore, observed and calculated soil moisture anomalies have a broad frequency distribution but not the strongly bimodal distribution indicative of water recycling. Compared to antecedent precipitation, soil moisture is a better predictor for future monthly temperature. Soil moisture can provide extra skill in predicting temperature in large areas of interior continent in summer, particularly at longer leads. The predictive skill of soil moisture is even higher when the predictand is daily maximum temperature instead of daily mean temperature. 31 refs., 10 figs.

  11. Factors Affecting Date of Implantation, Parturition, and Den Entry Estimated from Activity and Body Temperature in Free-Ranging Brown Bears

    PubMed Central

    Friebe, Andrea; Evans, Alina L.; Arnemo, Jon M.; Blanc, Stéphane; Brunberg, Sven; Fleissner, Günther; Swenson, Jon E.; Zedrosser, Andreas

    2014-01-01

    Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. We compared mean daily body temperature and activity levels of pregnant and nonpregnant females during preimplantation, gestation, and lactation. Additionally we tested whether age, litter size, primiparity, environmental conditions, and the start of hibernation influence the timing of parturition. The mean date of implantation was 1 December (SD = 12), the mean date of parturition was 26 January (SD = 12), and the mean duration of the gestation period was 56 days (SD = 2). The body temperature of pregnant females was higher during the gestation and lactation periods than that of nonpregnant bears. The body temperature of pregnant females decreased during the gestation period. Activity recordings were also used to determine the date of parturition. The parturition dates calculated with activity and body temperature data did not differ significantly and were the same in 50% of the females. Older females started hibernation earlier. The start of hibernation was earlier during years with favorable environmental conditions. Dates of parturition were later during years with good environmental conditions which was unexpected. We suggest that free-ranging pregnant brown bears in areas with high levels of human activities at the beginning of the denning period, as in our study area, might prioritize investing energy in early denning than in early parturition during years with favorable environmental conditions, as a strategy to prevent disturbances caused by human. PMID:24988486

  12. Seasonal microbial and nutrient responses during a 5-year reduction in the daily temperature range of soil in a Chihuahuan Desert ecosystem.

    PubMed

    van Gestel, Natasja C; Dhungana, Nirmala; Tissue, David T; Zak, John C

    2016-01-01

    High daily temperature range of soil (DTRsoil) negatively affects soil microbial biomass and activity, but its interaction with seasonal soil moisture in regulating ecosystem function remains unclear. For our 5-year field study in the Chihuahuan Desert, we suspended shade cloth 15 cm above the soil surface to reduce daytime temperature and increase nighttime soil temperature compared to unshaded plots, thereby reducing DTRsoil (by 5 ºC at 0.2 cm depth) without altering mean temperatures. Microbial biomass production was primarily regulated by seasonal precipitation with the magnitude of the response dependent on DTRsoil. Reduced DTRsoil more consistently increased microbial biomass nitrogen (MBN; +38%) than microbial biomass carbon (MBC) with treatment responses being similar in spring and summer. Soil respiration depended primarily on soil moisture with responses to reduced DTRsoil evident only in wetter summer soils (+53%) and not in dry spring soils. Reduced DTRsoil had no effect on concentrations of dissolved organic C, soil organic matter (SOM), nor soil inorganic N (extractable NO3 (-)-N + NH4 (+)-N). Higher MBN without changes in soil inorganic N suggests faster N cycling rates or alternate sources of N. If N cycling rates increased without a change to external N inputs (atmospheric N deposition or N fixation), then productivity in this desert system, which is N-poor and low in SOM, could be negatively impacted with continued decreases in daily temperature range. Thus, the future N balance in arid ecosystems, under conditions of lower DTR, seems linked to future precipitation regimes through N deposition and regulation of soil heat load dynamics.

  13. Seasonal microbial and nutrient responses during a 5-year reduction in the daily temperature range of soil in a Chihuahuan Desert ecosystem.

    PubMed

    van Gestel, Natasja C; Dhungana, Nirmala; Tissue, David T; Zak, John C

    2016-01-01

    High daily temperature range of soil (DTRsoil) negatively affects soil microbial biomass and activity, but its interaction with seasonal soil moisture in regulating ecosystem function remains unclear. For our 5-year field study in the Chihuahuan Desert, we suspended shade cloth 15 cm above the soil surface to reduce daytime temperature and increase nighttime soil temperature compared to unshaded plots, thereby reducing DTRsoil (by 5 ºC at 0.2 cm depth) without altering mean temperatures. Microbial biomass production was primarily regulated by seasonal precipitation with the magnitude of the response dependent on DTRsoil. Reduced DTRsoil more consistently increased microbial biomass nitrogen (MBN; +38%) than microbial biomass carbon (MBC) with treatment responses being similar in spring and summer. Soil respiration depended primarily on soil moisture with responses to reduced DTRsoil evident only in wetter summer soils (+53%) and not in dry spring soils. Reduced DTRsoil had no effect on concentrations of dissolved organic C, soil organic matter (SOM), nor soil inorganic N (extractable NO3 (-)-N + NH4 (+)-N). Higher MBN without changes in soil inorganic N suggests faster N cycling rates or alternate sources of N. If N cycling rates increased without a change to external N inputs (atmospheric N deposition or N fixation), then productivity in this desert system, which is N-poor and low in SOM, could be negatively impacted with continued decreases in daily temperature range. Thus, the future N balance in arid ecosystems, under conditions of lower DTR, seems linked to future precipitation regimes through N deposition and regulation of soil heat load dynamics. PMID:26391383

  14. Factors affecting date of implantation, parturition, and den entry estimated from activity and body temperature in free-ranging brown bears.

    PubMed

    Friebe, Andrea; Evans, Alina L; Arnemo, Jon M; Blanc, Stéphane; Brunberg, Sven; Fleissner, Günther; Swenson, Jon E; Zedrosser, Andreas

    2014-01-01

    Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. We compared mean daily body temperature and activity levels of pregnant and nonpregnant females during preimplantation, gestation, and lactation. Additionally we tested whether age, litter size, primiparity, environmental conditions, and the start of hibernation influence the timing of parturition. The mean date of implantation was 1 December (SD = 12), the mean date of parturition was 26 January (SD = 12), and the mean duration of the gestation period was 56 days (SD = 2). The body temperature of pregnant females was higher during the gestation and lactation periods than that of nonpregnant bears. The body temperature of pregnant females decreased during the gestation period. Activity recordings were also used to determine the date of parturition. The parturition dates calculated with activity and body temperature data did not differ significantly and were the same in 50% of the females. Older females started hibernation earlier. The start of hibernation was earlier during years with favorable environmental conditions. Dates of parturition were later during years with good environmental conditions which was unexpected. We suggest that free-ranging pregnant brown bears in areas with high levels of human activities at the beginning of the denning period, as in our study area, might prioritize investing energy in early denning than in early parturition during years with favorable environmental conditions, as a strategy to prevent disturbances caused by human.

  15. Analysis of Model-Calculated Soil Moisture over the United States (1931-1993) and Applications to Long-Range Temperature Forecasts.

    NASA Astrophysics Data System (ADS)

    Huang, Jin; van den Dool, Huug M.; Georgarakos, Konstantine P.

    1996-06-01

    A long time series of monthly soil moisture data during the period of 1931-1993 over the entire U.S. continent has been created with a one-layer soil moisture model. The model is based on the water budget in the soil and uses monthly temperature and monthly precipitation as input. The data are for 344 U.S. climate divisions during the period of 1931-1993. The main goals of this paper are 1) to improve our understanding of soil moisture and its effects on the atmosphere and 2) to apply the calculated soil moisture toward long-range temperature forecasts.In this study, the model parameters are estimated using observed precipitation, temperature, and runoff in Oklahoma (1960-1989) and applied to the entire United States. The comparison with the 8-yr (1984-1991) observed soil moisture in Illinois indicates that the model gives a reasonable simulation of soil moisture with both climatology and interannual variability.The analyses of the calculated soil moisture show that the climatological soil moisture is high in the east and low in the west (except the West Coast), which is determined by the climatological precipitation amounts. The annual cycle of soil moisture, however, is determined largely by evaporation. Anomalies in soil moisture are driven by precipitation anomalies, but their timescales are to first order determined by both climatological temperature (through evaporation) and climatological precipitation. The soil moisture anomaly persistence is higher where normal temperature and precipitation are low, which is the case in the west in summer. The spatial scale of soil moisture anomalies has been analyzed and found to be larger than that of precipitation but smaller than that of temperature.Authors found that generally in the U.S. evaporation anomalies are much smaller in magnitude than precipitation anomalies. Furthermore, observed and calculated soil moisture anomalies have a broad frequency distribution but not the strongly bimodal distribution indicative

  16. Effects of increase in temperature and open water on transmigration and access to health care by the Nenets reindeer herders in northern Russia

    PubMed Central

    Amstislavski, Philippe; Zubov, Leonid; Chen, Herman; Ceccato, Pietro; Pekel, Jean-Francois; Weedon, Jeremy

    2013-01-01

    Background The indigenous Nenets reindeer herders in northern Russia annually migrate several hundred kilometers between summer and winter pastures. In the warming climate, ice-rich permafrost and glaciers are being significantly reduced and will eventually disappear from parts of the Arctic. The emergent changes in hydrological cycles have already led to substantial increases in open water that stays unfrozen for longer periods of time. This environmental change has been reported to compromise the nomadic Nenets’ traditional way of life because the presence of new water in the tundra reduces the Nenets’ ability to travel by foot, sled, or motor vehicle from the summer transitory tundra campsites in order to access healthcare centers in villages. New water can also impede their access to family and community at other herder camps and in the villages. Although regional and global models predicting hydrologic changes due to climate changes exist, the spatial resolution of these models is too coarse for studying how increases in open water affect health and livelihoods. To anticipate the full health impact of hydrologic changes, the current gap between globally forecasted scenarios and locally forecasted hydrologic scenarios needs to be bridged. Objectives We studied the effects of the autumn temperature anomalies and increases in open water on health care access and transmigration of reindeer herders on the Kanin Peninsula. Design Correlational and time series analyses were completed. Methods The study population consisted of 370 full-time, nomadic reindeer herders. We utilized clinical visit records, studied surface temperature anomalies during autumn migrations, and used remotely sensed imagery to detect water bodies. Spearman correlation was used to measure the relationship between temperature anomalies and the annual arrival of the herders at the Nes clinic for preventive and primary care. Piecewise regression was used to model change in mean autumnal

  17. First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50-700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Rey, M.; Delahaye, T.; Nikitin, A. V.; Tyuterev, Vl. G.

    2016-10-01

    We present the construction of complete and comprehensive ethylene line lists for the temperatures 50-700 K based on accurate ab initio potential and dipole moment surfaces and extensive first-principle calculations. Three lists spanning the [0-6400] cm-1 infrared region were built at T = 80, 160, and 296 K, and two lists in the range [0-5200] cm-1 were built at 500 and 700 K. For each of these five temperatures, we considered possible convergence problems to ensure reliable opacity calculations. Our final list at 700 K was computed up to J = 71 and contains almost 60 million lines for intensities I > 5 × 10-27 cm/molecule. Comparisons with experimental spectra carried out in this study showed that for the most active infrared bands, the accuracy of band centers in our theoretical lists is better on average than 0.3 cm-1, and the integrated absorbance errors in the intervals relevant for spectral analyses are about 1-3%. These lists can be applied to simulations of absorption and emission spectra, radiative and non-LTE processes, and opacity calculations for planetary and astrophysical applications. The lists are freely accessible through the TheoReTS information system at http://theorets.univ-reims.fr and http://theorets.tsu.ru

  18. Absolute rate constant and O(3P) yield for the O(1D)+N2O reaction in the temperature range 227 K to 719 K

    NASA Astrophysics Data System (ADS)

    Vranckx, S.; Peeters, J.; Carl, S. A.

    2008-10-01

    The absolute rate constant for the reaction that is the major source of stratospheric NOx, O(1D)+N2O → products, has been determined in the temperature range 227 K to 719 K, and, in the temperature range 248 K to 600 K, the fraction of the reaction that yields O(3P). Both the rate constants and product yields were determined using a recently-developed chemiluminescence technique for monitoring O(1D) that allows for higher precision determinations for both rate constants, and, particularly, O(3P) yields, than do other methods. We found the rate constant, kR1, to be essentially independent of temperature between 400 K and 227 K, having a value of (1.37±0.11)×10-10 cm3 s-1, and for temperatures greater than 450 K a marked decrease in rate constant was observed, with a rate constant of only (0.94±0.11)×10-10 cm3 s-1 at 719 K. The rate constants determined over the 227 K 400 K range show very low scatter and are significantly greater, by 20% at room temperature and 15% at 227 K, than the current recommended values. The fraction of O(3P) produced in this reaction was determined to be 0.002±0.002 at 250 K rising steadily to 0.010±0.004 at 600 K, thus the channel producing O(3P) can be entirely neglected in atmospheric kinetic modeling calculations. A further result of this study is an expression of the relative quantum yields as a function of temperature for the chemiluminescence reactions (kCL1)C2H + O(1D) → CH(A) + CO and (kCL2)C2H + O(3P) → CH(A) + CO, both followed by CH(A) → CH(X) + hν, as kCL1(T)/kCL2(T)=(32.8T-3050)/(6.29T+398).

  19. Absolute rate constant and O(3P) yield for the O(1D)+N2O reaction in the temperature range 227 K to 719 K

    NASA Astrophysics Data System (ADS)

    Vranckx, S.; Peeters, J.; Carl, S. A.

    2008-05-01

    We have determined, in the temperature range 227 K to 719 K, the absolute rate constant for the reaction O(1D)+N2O → products and, in the temperature range 248 K to 600 K, the fraction of the reaction that yields O(3P). Both the rate constants and product yields were determined using a recently-developed chemiluminescence technique for monitoring O(1D) that allows for higher precision determinations for both rate constants, and, particularly, O(3P) yields, than do other methods. We found the rate constant, kR1, to be essentially independent of temperature between 400 K and 227 K, having a value of (1.37±0.09)×10-10 cm3 s-1. For temperatures greater than 450 K a marked decrease in value was observed, with a rate constant of only (0.94±0.11)×10-10 cm3 s-1 at 719 K. The rate constants determined over the 227 K-400 K range show very low scatter and are significantly greater, by 20% at room temperature and by 15% at 227 K, than the current recommended values. The fraction of O(3P) produced in this reaction was determined to be 0.002±0.002 at 250 K rising steadily to 0.010±0.004 at 600 K, thus the channel producing O(3P) can be entirely neglected in atmospheric kinetic modeling calculations. A further result of this study is an expression of the relative quantum yields as a function of temperature for the chemiluminescence reactions (kCL1) C2H+O(1D) → CH(A)+CO and (kCL2) C2H+O(3P) → CH(A)+CO, both followed by CH(A) → CH(X)+hν, as kCL1(T)/kCL2(T)=(32.8T-3050)/(6.29T+398).

  20. Characteristics of individual reactions of the cardiovascular system of healthy people to changes in meteorological factors in a wide temperature range

    NASA Astrophysics Data System (ADS)

    Zenchenko, T. A.; Skavulyak, A. N.; Khorseva, N. I.; Breus, T. K.

    2013-12-01

    Based on the results of 4-year observations of daily variations in blood pressure (BP) and heart rate (HR) in seven healthy volunteers, two distinct types of reaction of physiological indicators (PIs) to changes in meteorological parameters (first and foremost, atmospheric temperature T atm) are revealed. The first type is a monotonic (but nonuniform with respect to speed) decrease in systolic BP with increasing temperature, which is most pronounced for T atm < -5°C and T atm > 15°C, with a weaker reaction of diastolic BP and no reaction of HR (in four volunteers). The second type is a two-phase nonmonotonic dependence of BP indicators on T atm, which coincides with the first type in the range T atm < -5°C and is characterized by a positive correlation of BP and HR indicators with T atm for T atm > -5°C (in two volunteers). The physiological mechanisms that can provide the observed compensatory-adaptive reactions of healthy individuals to atmospheric factors in different temperature ranges are analyzed in detail. It has been shown that the revealed regularities can explain the results obtained by the authors in earlier studies.