The effect of temperature on the sensitivity of Daphnia magna to cyanobacteria is genus dependent.

PubMed

Hochmuth, Jennifer D; De Schamphelaere, Karel A C

2014-10-01

In the present study, the authors investigated the effects of 6 different genera of cyanobacteria on multiple endpoints of Daphnia magna in a 21-d life table experiment conducted at 3 different temperatures (15 °C, 19 °C, and 23 °C). The specific aims were to test if the effect of temperature on Daphnia's sensitivity to cyanobacteria differed among different cyanobacteria and if the rank order from most to least harmful cyanobacteria to Daphnia reproduction changed or remained the same across the studied temperature range. Overall, the authors observed a decrease in harmful effects on reproduction with increasing temperature for Microcystis, Nodularia, and Aphanizomenon, and an increase in harmful effects with increasing temperature for Anabaena and Oscillatoria. No effect of temperature was observed on Daphnia sensitivity to Cylindrospermopsis. Harmful effects of Microcystis and Nodularia on reproduction appear to be mirrored by a decrease in length. On the other hand, harmful effects of Anabaena, Aphanizomenon, and Oscillatoria on reproduction were correlated with a decrease in intrinsic rate of natural increase, which was matched by a later onset of reproduction in exposures to Oscillatoria. In addition, the results suggest that the cyanobacteria rank order of harmfulness may change with temperature. Higher temperatures may increase the sensitivity of D. magna to the presence of some cyanobacteria (Anabaena and Oscillatoria) in their diet, whereas the harmful effects of others (Microcystis, Nodularia, and Aphanizomenon) may be reduced by higher temperatures. © 2014 SETAC.

Skin blood flow and local temperature independently modify sweat rate during passive heat stress in humans.

PubMed

Wingo, Jonathan E; Low, David A; Keller, David M; Brothers, R Matthew; Shibasaki, Manabu; Crandall, Craig G

2010-11-01

Sweat rate (SR) is reduced in locally cooled skin, which may result from decreased temperature and/or parallel reductions in skin blood flow. The purpose of this study was to test the hypotheses that decreased skin blood flow and decreased local temperature each independently attenuate sweating. In protocols I and II, eight subjects rested supine while wearing a water-perfused suit for the control of whole body skin and internal temperatures. While 34°C water perfused the suit, four microdialysis membranes were placed in posterior forearm skin not covered by the suit to manipulate skin blood flow using vasoactive agents. Each site was instrumented for control of local temperature and measurement of local SR (capacitance hygrometry) and skin blood flow (laser-Doppler flowmetry). In protocol I, two sites received norepinephrine to reduce skin blood flow, while two sites received Ringer solution (control). All sites were maintained at 34°C. In protocol II, all sites received 28 mM sodium nitroprusside to equalize skin blood flow between sites before local cooling to 20°C (2 sites) or maintenance at 34°C (2 sites). In both protocols, individuals were then passively heated to increase core temperature ~1°C. Both decreased skin blood flow and decreased local temperature attenuated the slope of the SR to mean body temperature relationship (2.0 ± 1.2 vs. 1.0 ± 0.7 mg·cm(-2)·min(-1)·°C(-1) for the effect of decreased skin blood flow, P = 0.01; 1.2 ± 0.9 vs. 0.07 ± 0.05 mg·cm(-2)·min(-1)·°C(-1) for the effect of decreased local temperature, P = 0.02). Furthermore, local cooling delayed the onset of sweating (mean body temperature of 37.5 ± 0.4 vs. 37.6 ± 0.4°C, P = 0.03). These data demonstrate that local cooling attenuates sweating by independent effects of decreased skin blood flow and decreased local skin temperature.

Effect of storage and drying temperature on the gelation behavior and structural characteristics of sericin.

PubMed

Jo, Yoon Nam; Park, Byung-Dae; Um, In Chul

2015-11-01

Owing to unique properties, including the wound healing effect, sericin gel and films have attracted significant attention in the biomedical and cosmetic fields. The structural characteristics and properties of sericin gels and films are especially important owing to their effect on the performance of sericin in biomedical and cosmetic applications. In the present study, the effect of temperature on the gelation behavior, gel disruption, and sol-gel transition of sericin was examined using rheometry. In addition, the effect of the drying temperature on the structural characteristics of the sericin film was determined via Fourier transform infrared (FTIR) spectroscopy. The strength of the sericin gel increased and the gelation process was prolonged with decreasing storage temperatures. FTIR and differential scanning calorimetry (DSC) results also revealed that the crystallinity and the thermal decomposition temperature of the sericin film increased with decreasing drying temperature. The sericin gels were disrupted at a storage time of 40min when they were stored at temperatures higher than 50°C, and the corresponding gel strength decreased with increasing temperature. Furthermore, the thermo-reversible nature of gel-sol transition of sericin was confirmed by rheological and FTIR measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of temperature on size and development in three species of benthic copepod.

PubMed

Abdullahi, B A; Laybourn-Parry, Johanna

1985-09-01

The effect of temperature on the size and development times of three benthic cyclopoid copepods, Acanthocyclops viridis, A. vernalis and Macrocyclops albidus were investigated within the normal environmental temperature range (5°C-20°C). Adult weight decreased as temperature increased. All three species complete their development at 5°C and development times at all temperatures are presented as curvilinear logarithmic temperature functions. The duration of development decreases as temperature rises. The results are compared with those reported else-where for benthic and planktonic species and the ecological implications are discussed.

A time series study on the effects of cold temperature on road traffic injuries in Seoul, Korea.

PubMed

Lee, Won-Kyung; Lee, Hye-Ah; Hwang, Seung-sik; Kim, Ho; Lim, Youn-Hee; Hong, Yun-Chul; Ha, Eun-Hee; Park, Hyesook

2014-07-01

Although traffic accidents are associated with weather, the influence of temperature on injuries from traffic accidents has not been evaluated sufficiently. The objective of this study was to evaluate the effect of temperature, especially cold temperatures, on injuries from traffic accidents in Seoul, Korea. We also explored the relationship of temperature with different types of traffic accident. The daily frequencies of injuries from traffic accidents in Seoul were summarized from the integrated database established by the Korea Road Traffic Authority. Weather data included temperature, barometric pressure, rainfall, snow, and fog from May 2007 to December 2011. The qualitative relationship between daily mean temperature and injuries from traffic accidents was evaluated using a generalized additive model with Poisson distribution. Further analysis was performed using piecewise linear regression if graph the showed non-linearity with threshold. The incidence of injuries was 216 per 100,000 person-months in Seoul. The effect of temperature on injuries from traffic accidents was minimal during spring and summer. However, injuries showed a more striking relationship with temperature in winter than in other seasons. In winter, the number of injuries increased as the temperature decreased to <0°C. The injuries increased by 2.1% per 1°C decrease under the threshold of the daily average temperature -5.7°C, which is 10-fold greater than the effect of temperature above the threshold. Some groups were more susceptible to injuries, such as young and male drivers, according to the types of traffic accident when the temperature decreased to below the freezing temperature. The incidence of injuries increased sharply when the temperature decreased below freezing temperature in winter. Temperature can be effectively used to inform high risk of road traffic injuries, thus helping to prevent road traffic injuries. Copyright © 2014 Elsevier Inc. All rights reserved.

Combustion characteristics of fine- and micro-pulverized coal in the mixture of O{sub 2}/CO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiangyong Huang; Xiumin Jiang; Xiangxin Han

The effects of oxygen concentration, particle size, and heating rate on the coal combustion characteristics under an O{sub 2}/CO{sub 2} atmosphere were investigated. The results indicated that the oxygen concentration played the most important role. As the oxygen concentration increases, the ignition and burnout temperatures decrease and the comprehensive combustion property index S increases. Moreover, the improvement of the oxygen concentration intensified the effects of the other factors. The ignition mechanism changes from hetero-homogeneous type to homogeneous type as the oxygen concentration increases. The ignition and burnout temperatures decrease slightly as the mean particle size decreases, and the index Smore » increases measurably as the mean particle size decreases. The heating rate has different effects on the ignition temperature, burnout temperature, and index S at different oxygen concentrations. 19 refs., 9 figs., 2 tabs.« less

Effects of temperature at constant air dew point on leaf carboxylation efficiency and CO2 compensation point of different leaf types.

PubMed

Weber, J A; Tenhunen, J D; Lange, O L

1985-09-01

The effect of temperature on photosynthesis at constant water-vapor pressure in the air was investigated using two sclerophyll species, Arbutus unedo and Quercus suber, and one mesophytic species, Spinacia oleracea. Photosynthesis and transpiration were measured over a range of temperatures, 20-39° C. The external concentration of CO2 was varied from 340 μbar to near CO2 compensation. The initial slope (carboxylation efficiency, CE) of the photosynthetic response to intercellular CO2 concentration, the CO2 compensation point (Γ), and the extrapolated rate of CO2 released into CO2-free air (R i) were calculated. At an external CO2 concentration of 320-340 μbar CO2, photosynthesis decreased with temperature in all species. The effect of temperature on Γ was similar in all species. While CE in S. oleracea changed little with temperature, CE decreased by 50% in Q. suber as temperature increased from 25 to 34° C. Arbutus unedo also exhibited a decrease in CE at higher temperatures but not as marked as Q. suber. The absolut value of R i increased with temperature in S. oleracea, while changing little or decreasing in the sclerophylls. Variations in Γ and R i of the sclerophyll species are not consistent with greater increase of respiration with temperature in the light in these species compared with S. oleracea.

[Effects of climate change on flax development and yield in Guyuan of Ningxia, Northwest China].

PubMed

Li, Shu-Zhen; Sun, Lin-Li; Ma, Yu-Ping; Ma, Yu-Ping; Xu, Yu-Dong; E, You-Hao

2014-10-01

Based on variations of the annual mean temperature and precipitation analyzed using ob- servation data in Guyuan of Ningxia, the effects of climate change on the local flax developmental process and yield were investigated. The results showed that the annual mean temperature had an increasing trend (0.3 °C · (10 a)-1) and the annual precipitation had a decreasing trend (-20 mm · (10 a) -1) from 1957 to 2012. While the increasing trend of mean temperature during growing season of flax was more obviously than that of the annual temperature, the decreasing trend of precipitation during growing season was similar to that of annual precipitation. With temperature increasing and precipitation decreasing, the flax development rate was accelerated, resulting in the reduced growing period. Seedling stage was advanced 0.7 d with 1 °C increase in temperature during the period from sowing to seedling emergence. The duration from seedling emergence to two pairs of needles was shortened by 0.8 d with 1 °C increase in temperature and 0.1 d with 1 mm decrease in precipitation. Maturity stage was advanced 1.8 d with 1 °C increase in temperature and 0.1 d with 1 mm decrease in precipitation during the period from technical maturity to maturity. The flax development was accelerated because of temperature increasing and precipitation decreasing in the vegetative growth phase, which was one of the main causes of flax yield reduction year by year. Meanwhile, flower bud differentiation and pollination of flax were influenced by temperature increasing in the reproductive growth phase, which would affect the number of capsules and the seed setting rate per plant and lead to the decrease of flax yield. Therefore, adjusting plant structure and enlarging the planting area of late or middle-late variety were the important measures to reduce the effects of climate change on local flax production.

Temperature dependence of frequency response characteristics in organic field-effect transistors

NASA Astrophysics Data System (ADS)

Lu, Xubing; Minari, Takeo; Liu, Chuan; Kumatani, Akichika; Liu, J.-M.; Tsukagoshi, Kazuhito

2012-04-01

The frequency response characteristics of semiconductor devices play an essential role in the high-speed operation of electronic devices. We investigated the temperature dependence of dynamic characteristics in pentacene-based organic field-effect transistors and metal-insulator-semiconductor capacitors. As the temperature decreased, the capacitance-voltage characteristics showed large frequency dispersion and a negative shift in the flat-band voltage at high frequencies. The cutoff frequency shows Arrhenius-type temperature dependence with different activation energy values for various gate voltages. These phenomena demonstrate the effects of charge trapping on the frequency response characteristics, since decreased mobility prevents a fast charge response for alternating current signals at low temperatures.

Lauroyl-L-aspartate decreased food intake and body temperature in neonatal chicks.

PubMed

Erwan, E; Chowdhury, V S; Ito, K; Furuse, M

2013-11-15

We hypothesized that the effects of L- and D-amino acids might be influenced when conjugated with fatty acid. Thus, the effects of oral administration of lauroyl-L-aspartate (Lau-L-Asp) as well as lauroyl-D-aspartate (Lau-D-Asp) were examined. In Experiment 1, oral administration of both Lau-L-Asp and Lau-D-Asp decreased food intake while L- or D-Asp did not influence food intake. Interestingly, only Lau-L-Asp decreased body temperature. Experiment 2 was conducted to determine whether non-conjugated mixture of L-Asp plus lauric acid has same effects under ad libitum feeding conditions. Lau-L-Asp decreased food intake and body temperature, but L-Asp plus lauric acid did not show any effect studied. In Experiment 3, we found that Lau-L-Asp declined food intake as well as time-dependently suppressed the body temperature in fasted chicks. However, L-Asp plus lauric acid did not show any effect. These results suggest that Lau-L-Asp may exert anorexigenic and hypothermic actions in chicks. © 2013.

Effects of Strain Rate and Temperature on the Mechanical Properties of Medium Manganese Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, Radhakanta; Matlock, David K; Speer, John G

2016-11-16

The effects of temperature (-60 to 100 °C) and strain rate (0.002 to 0.2 s-1) on the properties of Al-alloyed 7 and 10 wt-% Mn steels containing 34.8 and 57.3 vol-% austenite respectively were evaluated by tensile tests in isothermal liquid baths. The tensile strengths of both medium Mn steels increased with a decrease in temperature owing to the decreased austenite stability with a decrease in temperature. At lower temperatures the strength of the 10MnAl steel was highest, a consequence of the higher strain hardening rate caused by more austenite transformation to martensite with deformation. The resulting properties are assessedmore » with a consideration of the effects of strain rate and deformation on adiabatic heating which was observed to be as high as 95o C.« less

Magnetocaloric effect and magnetic properties in SmFe1-xMnxO3 perovskite: Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Erchidi Elyacoubi, A. S.; Masrour, R.; Jabar, A.

2018-03-01

We have used Monte Carlo simulation to study the magnetocaloric effect on SmFe1-xMnxO3 perovskite. The temperature-dependent magnetization shows that the Néel temperature of the weak-ferromagnetic SmFeO3 decreases as Fe ions are substituted by Mn ions. A paramagnetic-to-weak-antiferromagnetic transition with decreasing the temperature is observed and the corresponding Néel temperature essentially decreases as the Mn content increases. The magnetocaloric effect shows two peaks related to magnetic behavior changes, at paramagnetic-like behavior TK(K) and at Néel temperature TN(K) of SmFe1-xMnxO3. The second phase transition is established. The magnetic entropy change is given for a several magnetic fields. We have also determined the relative cooling power for dilution x = 0.5 and for a several external magnetic fields. Finally, the magnetic hysteresis cycles have been obtained with different dilutions x and temperatures values.

[Effect of temperature on performance of microbial fuel cell using beer wastewater].

PubMed

Wang, Xin; Feng, Yu-Jie; Qu, You-Peng; Li, Dong-Mei; Li, He; Ren, Nan-Qi

2008-11-01

The effects of temperature on performance and biological community structure were investigated in air-cathode microbial fuel cells (MFCs) using beer wastewater amended with 50 mmol/L phosphate buffer solution (PBS). The maximum power density decreased from 483 mW/m2 to 435 mW/m2 when the temperature varied from 30 degrees C to 20 degrees C, meanwhile just a little decreasing on coulombic efficiency and the COD removal rate were observed. Decreasing of temperature resulted in effects both on cathode potential and anode potential, but cathode potential behaved much more sensitive to temperature. The half-saturation constants (Ks) obtained from the fit of Monod-type equation were 228 mg/L (30 degrees C) and 293 mg/L (20 degrees C) respectively. Denaturing gradient gel electrophoresis (DGGE) analysis indicated that operating temperature not only affected the predominant population of the anodic bacterial community, but also had a great impact on the diversity of the cathodic microbial population.

Memory effect versus exchange bias for maghemite nanoparticles

NASA Astrophysics Data System (ADS)

Nadeem, K.; Krenn, H.; Szabó, D. V.

2015-11-01

We studied the temperature dependence of memory and exchange bias effects and their dependence on each other in maghemite (γ-Fe2O3) nanoparticles by using magnetization studies. Memory effect in zero field cooled process in nanoparticles is a fingerprint of spin-glass behavior which can be due to i) surface disordered spins (surface spin-glass) and/or ii) randomly frozen and interacting nanoparticles core spins (super spin-glass). Temperature region (25-70 K) for measurements has been chosen just below the average blocking temperature (TB=75 K) of the nanoparticles. Memory effect (ME) shows a non-monotonous behavior with temperature. It shows a decreasing trend with decreasing temperature and nearly vanishes below 30 K. However it also decreased again near the blocking temperature of the nanoparticles e.g., 70 K. Exchange bias (EB) in these nanoparticles arises due to core/shell interface interactions. The EB increases sharply below 30 K due to increase in core/shell interactions, while ME starts vanishing below 30 K. We conclude that the core/shell interface interactions or EB have not enhanced the ME but may reduce it in these nanoparticles.

Diffusion-weighted magnetic resonance imaging reveals the effects of different cooling temperatures on the diffusion of water molecules and perfusion within human skeletal muscle.

PubMed

Yanagisawa, O; Fukubayashi, T

2010-11-01

To evaluate the effect of local cooling on the diffusion of water molecules and perfusion within muscle at different cooling temperatures. Magnetic resonance diffusion-weighted (DW) images of the leg (seven males) were obtained before and after 30 min cooling (0, 10, and 20°C), and after a 30 min recovery period. Two types of apparent diffusion coefficient (ADC; ADC1, reflecting both water diffusion and perfusion within muscle, and ADC2, approximating the true water diffusion coefficient) of the ankle dorsiflexors were calculated from DW images. T2-weighted images were also obtained to calculate T2 values of the ankle dorsiflexors. The skin temperature was measured before, during, and after cooling. Both ADC values significantly decreased after cooling under all cooling conditions; the rate of decrease depended on the cooling temperature used (ADC1: -36% at 0°C, -27.8% at 10°C, and -22.6% at 20°C; ADC2: -26% at 0°C, -21.1% at 10°C, and -14.6% at 20°C). These significant decreases were maintained during the recovery period. Conversely, the T2 value showed no significant changes. Under all cooling conditions, skin temperature significantly decreased during cooling; the rate of decrease depended on the cooling temperature used (-74.8% at 0°C, -51.1% at 10°C, and -26.8% at 20°C). Decreased skin temperatures were not restored to pre-cooling values during the recovery period under any cooling conditions. Local cooling decreased the water diffusion and perfusion within muscle with decreased skin temperature; the rates of decrease depended on the cooling temperature used. These decreases were maintained for 30 min after cooling. Copyright © 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Aging phenomena in poly(methyl methacrylate) thin films: Memory and rejuvenation effects

NASA Astrophysics Data System (ADS)

Fukao, K.; Sakamoto, A.

2005-04-01

The aging dynamics in thin films of poly(methyl methacrylate) (PMMA) have been investigated through dielectric measurements for different types of aging processes. The dielectric constant was found to decrease with increasing aging time at an aging temperature in many cases. An increase in the dielectric constant was also observed in the long-time region (⩾11h) near the glass transition temperature for thin films with thickness less than 26nm . In the constant-rate mode including a temporary stop at a temperature Ta , the memory of the aging at Ta was found to be kept and then to be recalled during the subsequent heating process. In the negative-temperature cycling process, a strong rejuvenation effect has been observed after a temperature shift from the initial temperature T1 to the second temperature T2 (=T1+ΔT) when ΔT≈-20K . Furthermore, a full memory effect has also been observed for the temperature shift from T2 to T1 . This suggests that the aging at T1 is totally independent of that at T2 for ΔT≈-20K . As ∣ΔT∣ decreases, the independence of the aging between the two temperatures was found to be weakened—i.e., the effective time, which is a measure of the contribution of the aging at T1 to that at T2 , is a decreasing function of ∣ΔT∣ in the negative region of ΔT . As the film thickness decreases from 514nmto26nm , the ∣ΔT∣ dependence of the effective time was found to become much stronger. The contribution of the aging at T2 to that at T1 disappears more rapidly with increasing ∣ΔT∣ in thin-film geometry than in the bulk state.

Temperature-dependent sorption of naphthalene, phenanthrene, and pyrene to low organic carbon aquifer sediments

USGS Publications Warehouse

Piatt, Joseph J.; Backhus, Debera A.; Capel, Paul D.; Eisenreich, Steven J.

1996-01-01

Sorption experiments were conducted with naphthalene, phenanthrene, and pyrene on low organic carbon sediments at 4 and 26 °C using batch and column techniques. Experimental controls ensured the absence of biologic and photolytic activity and colloid-free solution supernatants. Equilibrium distribution coefficients (Kd) increased 1.1−1.6 times with a decrease in temperature of 22 °C. Fraction instantaneous sorption (F) values did not change significantly with a decrease in temperature of 22 °C. Desorption rate constants (k2) decreased 1.2−2.6 times with a decrease in temperature of 22 °C. Times to equilibrium were at least 40 h. The magnitude of observed Kd and k2 values and the effect of temperature on Kd (e.g., low enthalpy of sorption) are consistent with sorbate partitioning between the aqueous phase and small amounts of organic matter (foc = 0.02%) on the sediments. The temperature dependence of Kd and k2 may be small as compared to the effects of heterogeneities in field-scale aquifer systems. Thus, thermal gradients may not be of major importance in most saturated subsurface regimes when predicting solute transport. However, aquifer remediation pump-and-treat times could be decreased because increased temperature decreases both retardation and tailing.

Effect of heat recovery from raw wastewater on nitrification and nitrogen removal in activated sludge plants.

PubMed

Wanner, Oskar; Panagiotidis, Vassileios; Clavadetscher, Peter; Siegrist, Hansruedi

2005-11-01

By recovery of heat from the raw wastewater in the sewer system, the influent temperature of a wastewater treatment plant (WWTP) is reduced. This can have a negative effect on nitrification in the WWTP, since this process strongly depends on temperature. The analysis of the temperature regime in the WWTP of Zurich, Switzerland, revealed that in the cold season, the effluent temperature is about 0.7 degrees C higher than the influent temperature and that nitrification is not affected by a decrease of the influent wastewater temperature lasting for a couple of hours only, but is significantly affected by a longer lasting temperature decrease. Three diagrams were developed with a steady-state model, from which the consequences of a permanent temperature decrease on the nitrification safety factor, aerobic sludge retention time and total nitrogen removal can be evaluated. Using simulations with a dynamic model, calibrated for the Zurich WWTP, a quantitative relationship between the wastewater temperature and the ammonium effluent concentration was established. This relationship can, in combination with measured effluent concentrations of an existing WWTP, be used to predict the increase of the ammonium effluent concentration in this plant resulting from a permanent decrease of the wastewater influent temperature.

Temperature shift experiments suggest that metabolic impairment and enhanced rates of photorespiration decrease organic acid levels in soybean leaflets exposed to supra-optimal growth temperatures

USDA-ARS?s Scientific Manuscript database

Citrate, malate, malonate, fumarate and succinate in soybean leaflets decreased 40 to 80% when plants were grown continuously in controlled environment chambers at 36/28 compared to 28/20 °C. Glycerate was not temperature responsive in this study. Temperature effects on the above mentioned organi...

The effects of thermal and high-CO2 stresses on the metabolism and surrounding microenvironment of the coral Galaxea fascicularis.

PubMed

Agostini, Sylvain; Fujimura, Hiroyuki; Higuchi, Tomihiko; Yuyama, Ikuko; Casareto, Beatriz E; Suzuki, Yoshimi; Nakano, Yoshikatsu

2013-08-01

The effects of elevated temperature and high pCO2 on the metabolism of Galaxea fascicularis were studied with oxygen and pH microsensors. Photosynthesis and respiration rates were evaluated from the oxygen fluxes from and to the coral polyps. High-temperature alone lowered both photosynthetic and respiration rates. High pCO2 alone did not significantly affect either photosynthesis or respiration rates. Under a combination of high-temperature and high-CO2, the photosynthetic rate increased to values close to those of the controls. The same pH in the diffusion boundary layer was observed under light in both (400 and 750 ppm) CO2 treatments, but decreased significantly in the dark as a result of increased CO2. The ATP contents decreased with increasing temperature. The effects of temperature on the metabolism of corals were stronger than the effects of increased CO2. The effects of acidification were minimal without combined temperature stress. However, acidification combined with higher temperature may affect coral metabolism due to the amplification of diel variations in the microenvironment surrounding the coral and the decrease in ATP contents. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Room-temperature annealing effects on the basal-plane resistivity of optimally doped YBa2Cu3O7-δ single crystals

NASA Astrophysics Data System (ADS)

Khadzhai, G. Ya.; Vovk, R. V.; Vovk, N. R.; Kamchatnaya, S. N.; Dobrovolskiy, O. V.

2018-02-01

We reveal that the temperature dependence of the basal-plane normal-state electrical resistance of optimally doped YBa2Cu3O7-δ single crystals can be with great accuracy approximated within the framework of the model of s-d electron-phonon scattering. This requires taking into account the fluctuation conductivity whose contribution exponentially increases with decreasing temperature and decreases with an increase of oxygen deficiency. Room-temperature annealing improves the sample and, thus, increases the superconducting transition temperature. The temperature of the 2D-3D crossover decreases during annealing.

Negative effect of nanoconfinement on water transport across nanotube membranes

NASA Astrophysics Data System (ADS)

Zhao, Kuiwen; Wu, Huiying; Han, Baosan

2017-10-01

Nanoconfinement environments are commonly considered advantageous for ultrafast water flow across nanotube membranes. This study illustrates that nanoconfinement has a negative effect on water transport across nanotube membranes based on molecular dynamics simulations. Although water viscosity and the friction coefficient evidently decrease because of nanoconfinement, water molecular flux and flow velocity across carbon nanotubes decrease sharply with the pore size of nanotubes. The enhancement of water flow across nanotubes induced by the decreased friction coefficient and water viscosity is markedly less prominent than the negative effect induced by the increased flow barrier as the nanotube size decreases. The decrease in water flow velocity with the pore size of nanotubes indicates that nanoconfinement is not essential for the ultrafast flow phenomenon. In addition, the relationship between flow velocity and water viscosity at different temperatures is investigated at different temperatures. The results indicate that flow velocity is inversely proportional to viscosity for nanotubes with a pore diameter above 1 nm, thereby indicating that viscosity is still an effective parameter for describing the effect of temperature on the fluid transport at the nanoscale.

The effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity

NASA Astrophysics Data System (ADS)

Owji, Erfan; Keshavarz, Alireza; Mokhtari, Hosein

2016-10-01

In this paper, the effects of temperature, hydrostatic pressure and size on optical gain for GaAs spherical quantum dot laser with hydrogen impurity are investigated. For this purpose, the effects of temperature, pressure and quantum dot size on the band gap energy, effective mass, and dielectric constant are studied. The eigenenergies and eigenstates for valence and conduction band are calculated by using Runge-Kutta numerical method. Results show that changes in the temperature, pressure and size lead to the alteration of the band gap energy and effective mass. Also, increasing the temperature redshifts the optical gain peak and at special temperature ranges lead to increasing or decreasing of it. Further, by reducing the size, temperature-dependent of optical gain is decreased. Additionally, enhancing of the hydrostatic pressure blueshifts the peak of optical gain, and its behavior as a function of pressure which depends on the size. Finally, increasing the radius rises the redshifts of the peak of optical gain.

Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate

ERIC Educational Resources Information Center

Science, 1971

1971-01-01

Mathematical models indicate increasing atmospheric carbon dioxide causes an increase in surface temperature at a decreasing rate, and the rate of temperature decrease caused by increasing aerosols increases with aerosol concentration. (AL)

Effects of temperature and copper pollution on soil community--extreme temperature events can lead to community extinction.

PubMed

Menezes-Oliveira, Vanessa B; Scott-Fordsmand, Janeck J; Soares, Amadeu M V M; Amorim, Monica J B

2013-12-01

Global warming affects ecosystems and species' diversity. The physiology of individual species is highly influenced by changes in temperature. The effects on species communities are less studied; they are virtually unknown when combining effects of pollution and temperature. To assess the effects of temperature and pollution in the soil community, a 2-factorial soil mesocosms multispecies experiment was performed. Three exposure periods (28 d, 61 d, and 84 d) and 4 temperatures (19 °C, 23 °C, 26 °C, and 29 °C) were tested, resembling the mean annual values for southern Europe countries and extreme events. The soil used was from a field site, clean, or spiked with Cu (100 mg Cu/kg). Results showed clear differences between 29 °C treatment and all other temperature treatments, with a decrease in overall abundance of organisms, further potentiated by the increase in exposure time. Folsomia candida was the most abundant species and Enchytraeus crypticus was the most sensitive to Cu toxicity. Differences in species optimum temperatures were adequately covered: 19 °C for Hypoaspis aculeifer or 26 °C for E. crypticus. The temperature effects were more pronounced the longer the exposure time. Feeding activity decreased with higher temperature and exposure time, following the decrease in invertebrate abundance, whereas for the same conditions the organic matter turnover increased. Hence, negative impacts on ecosystem services because of temperature increase can be expected by changes on soil function and as consequence of biodiversity loss. © 2013 SETAC.

Impacts of temperature and crowding on sex ratio, fecundity and Wolbachia infection intensity in the copepod, Mesocyclops thermocyclopoides.

PubMed

Wiwatanaratanabutr, Itsanun; Grandjean, Frederic

2016-11-01

Wolbachia are a group of intracellular bacteria that cause reproductive alterations in arthropods. Here, we describe the effects of two environmental factors (crowding and temperature) on phenotypic expression of feminization, the host's fecundity and Wolbachia infection intensity among life cycle stages in the naturally Wolbachia-infected copepod, Mesocyclops thermocyclopoides. The copepod was first found to be co-infected with Wolbachia A- and B-supergroups Wolbachia strains based on wsp primers. The relative Wolbachia infection intensity within individuals was determined using quantitative real-time PCR and was significantly higher in the B-supergroup than in the A-supergroup. Experimental results of temperature effect on bacterial density in each developmental stage revealed a significant decrease in Wolbachia infection intensity following exposure to high temperature (37°C) in both sexes and implied that Wolbachia might survive in room temperature (25°C) better than in high temperature. Experimental results of crowding effects on Wolbachia infection intensity suggested a negative correlation between copepod nauplii and Wolbachia infection intensity. No effect of rearing temperature on the sex ratio was reported although the fecundity was significantly decreased by high temperature. The results showed that Wolbachia infection intensity to be correlated with crowding conditions and was decreased following exposure of elevated temperature. Copyright © 2016 Elsevier Inc. All rights reserved.

Analysis of optimal design of low temperature economizer

NASA Astrophysics Data System (ADS)

Song, J. H.; Wang, S.

2017-11-01

This paper has studied the Off-design characteristic of low temperature economizer system based on thermodynamics analysis. Based on the data from one 1000 MW coal-fired unit, two modes of operation are contrasted and analyzed. One is to fix exhaust gas temperature and the other one is to take into account both of the average temperature difference and the exhaust gas temperature. Meanwhile, the cause of energy saving effect change is explored. Result shows that: in mode 1, the amount of decrease in coal consumption reduces from 1.11 g/kWh (under full load) to 0.54 g/kWh (under half load), and in mode 2, when the load decreases from 90% to 50%, the decrease in coal consumption reduces from 1.29 g/kWh to 0.84 g/kWh. From the result, under high load, the energy saving effect is superior, and under lower work load, energy saving effect declines rapidly when load is reduced. When load changes, the temperature difference of heat transfer, gas flow, the flue gas heat rejection and the waste heat recovery change. The energy saving effect corresponding changes result in that the energy saving effect under high load is superior and more stable. However, rational adjustment to the temperature of outlet gas can alleviate the decline of the energy saving effect under low load. The result provides theoretical analysis data for the optimal design and operation of low temperature economizer system of power plant.

Study on energy saving effect of IHX on vehicle air conditioning system

NASA Astrophysics Data System (ADS)

Li, Huguang; Tong, Lin; Xu, Ming; Wei, Wangrui; Zhao, Meng; Wang, Long

2018-02-01

In this paper, the performance of Internal Heat Exchanger (IHX) air conditioning system for R134a is investigated in bench test and vehicle test. Comparison for cooling capacity and energy consumption between IHX air conditioning system and traditional tube air conditioning system are conducted. The suction temperature and discharge temperature of compressor is also recorded. The results show that IHX air conditioning system has higher cooling capacity, the vent temperature decrease 2.3 °C in idle condition. But the suction temperature and discharge temperature of compressor increase 10°C. IHX air conditioning system has lower energy consumption than traditional tube air conditioning system. Under the experimental conditions in this paper, the application of IHX can significantly reduce the energy consumption of air conditioning system. At 25°C of environment temperature, AC system energy consumption decrease 14%, compressor energy consumption decrease 16%. At 37°C of environment temperature, AC system energy consumption decrease 16%, compressor energy consumption decrease 13%.

Effect of low sea water temperature on water balance in the Atlantic salmon, (Salmo salar L.).

PubMed

Lega, Y V; Chernitsky, A G; Belkovsky, N M

1992-08-01

The water balance in Atlantic salmon (Salmo salar L.) overwintering in sea water (34 ‰) was investigated. With a decrease of temperature from 5.6 to 1.0°C the drinking rate decreased from 13.9 to 5.7 ml/kg/day, and the absolute amount of water absorbed decreased from 8.9 to 5.0 ml/kg/day. A decrease in temperature led, however, to an increase in the proportion of water absorbed in the intestines from 60 to 96%. Blood serum osmolarity increased from 320 to 440 mosm/1 with decreasing temperature and there was a reduction in tissue water content from 75 to 69% The disturbance of water balance at low temperature may be one of the factors responsible for mortality of salmon overwintering in sea water.

Pion decay constant and the {rho}-meson mass at finite temperature in hidden local symmetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harada, M.; Shibata, A.

1997-06-01

We study the temperature dependence of the pion decay constant and {rho}-meson mass in the hidden local symmetry model at one loop. Using the standard imaginary time formalism, we include the thermal effect of the {rho} meson as well as that of the pion. We show that the pion gives a dominant contribution to the pion decay constant and the {rho}-meson contribution slightly decreases the critical temperature. The {rho}-meson pole mass increases as T{sup 4}/m{sub {rho}}{sup 2} at low temperature, dominated by the pion-loop effect. At high temperature, although the pion-loop effect decreases the {rho}-meson mass, the {rho}-loop contribution overcomesmore » the pion-loop contribution and the {rho}-meson mass increases with temperature. We also show that the conventional parameter a is stable as the temperature increases. {copyright} {ital 1997} {ital The American Physical Society}« less

Characteristics of maize biochar with different pyrolysis temperatures and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil.

PubMed

Wang, Xiubin; Zhou, Wei; Liang, Guoqing; Song, Dali; Zhang, Xiaoya

2015-12-15

In this study, the characteristics of maize biochar produced at different pyrolysis temperatures (300, 450 and 600°C) and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil were investigated. As pyrolysis temperature increased, ash content, pH, electrical conductivity, surface area, pore volume and aromatic carbon content of biochar increased while yield, ratios of oxygen:carbon and hydrogen: carbon and alkyl carbon content decreased. During incubation, SOC, total N, and ammonium-N contents increased in all biochar-amended treatments compared with the urea treatment; however, soil nitrate-N content first increased and then decreased with increasing pyrolysis temperature of the applied biochar. Extracellular enzyme activities associated with carbon transformation first increased and then decreased with biochars pyrolyzed at 450 and 600°C. Protease activity markedly increased with increased pyrolysis temperatures, whereas pyrolysis temperature had limited effect on soil urease activity. The results indicated that the responses of extracellular enzymes to biochar were dependent on the pyrolysis temperature, the enzyme itself and incubation time as well. Copyright © 2015. Published by Elsevier B.V.

Simultaneous effects of pressure and temperature on donor binding energy in Pöschl-Teller quantum well

NASA Astrophysics Data System (ADS)

Hakimyfard, Alireza; Barseghyan, M. G.; Duque, C. A.; Kirakosyan, A. A.

2009-12-01

In the frame of the variational method and the effective-mass approximation, the effects of hydrostatic pressure and temperature on the binding energy for donor impurities in the Pöschl-Teller quantum well are studied. The binding energy dependencies on the width of the quantum well, the hydrostatic pressure, the impurity position, the temperature, and the parameters of the confining potential are reported. The results show that the binding energy increases (decreases) with the increasing of the hydrostatic pressure (temperature). It is also found that, associated with the symmetry breaking in the Pöschl-Teller quantum well, and depending on the impurity position, the binding energy can increase or decrease.

Thermal conductivity of water-saturated rocks from the KTB pilot hole at temperatures of 25 to 300°C

USGS Publications Warehouse

Pribnow, D.; Williams, C.F.; Sass, J.H.; Keating, R.

1996-01-01

The conductivitites of selected gneiss (two) and amphibolite (one) core samples have been measured under conditions of elevated temperature and pressure with a needle-probe. Water-saturated thermal conductivity measurements spanning temperatures from 25 to 300??C and hydrostatic pressures of 0.1 and 34 MPa confirm the general decrease in conductivity with increasing temperature but deviate significantly from results reported from measurements on dry samples over the same temperature range. The thermal conductivity of water-saturated amphibolite decreases with temperature at a rate approximately 40% less than the rate for dry amphibolite, and the conductivity of water-saturated gneiss decreases at a rate approximately 20% less than the rate for dry gneiss. The available evidence points to thermal cracking as the primary cause of the more rapid decrease in dry thermal conductivity with temperature. The effects of thermal cracking were also observed in the water-saturated samples but resulted in a net decrease in room-temperature conductivity of less than 3%. These results highlight the importance of duplicating in-situ conditions when determining thermal conductivity for the deep crust.

Forest thinning and soil respiration in a ponderosa pine plantation in the Sierra Nevada.

PubMed

Tang, Jianwu; Qi, Ye; Xu, Ming; Misson, Laurent; Goldstein, Allen H

2005-01-01

Soil respiration is controlled by soil temperature, soil water, fine roots, microbial activity, and soil physical and chemical properties. Forest thinning changes soil temperature, soil water content, and root density and activity, and thus changes soil respiration. We measured soil respiration monthly and soil temperature and volumetric soil water continuously in a young ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) plantation in the Sierra Nevada Mountains in California from June 1998 to May 2000 (before a thinning that removed 30% of the biomass), and from May to December 2001 (after thinning). Thinning increased the spatial homogeneity of soil temperature and respiration. We conducted a multivariate analysis with two independent variables of soil temperature and water and a categorical variable representing the thinning event to simulate soil respiration and assess the effect of thinning. Thinning did not change the sensitivity of soil respiration to temperature or to water, but decreased total soil respiration by 13% at a given temperature and water content. This decrease in soil respiration was likely associated with the decrease in root density after thinning. With a model driven by continuous soil temperature and water time series, we estimated that total soil respiration was 948, 949 and 831 g C m(-2) year(-1) in the years 1999, 2000 and 2001, respectively. Although thinning reduced soil respiration at a given temperature and water content, because of natural climate variability and the thinning effect on soil temperature and water, actual cumulative soil respiration showed no clear trend following thinning. We conclude that the effect of forest thinning on soil respiration is the combined result of a decrease in root respiration, an increase in soil organic matter, and changes in soil temperature and water due to both thinning and interannual climate variability.

Hot Deformation and Dynamic Recrystallization Behavior of the Cu-Cr-Zr-Y Alloy

NASA Astrophysics Data System (ADS)

Zhang, Yi; Huili, Sun; Volinsky, Alex A.; Tian, Baohong; Chai, Zhe; Liu, Ping; Liu, Yong

2016-03-01

To study the workability and to optimize the hot deformation processing parameters of the Cu-Cr-Zr-Y alloy, the strain hardening effect and dynamic softening behavior of the Cu-Cr-Zr-Y alloy were investigated. The flow stress increases with the strain rate and stress decreases with deformation temperature. The critical conditions, including the critical strain and stress for the occurrence of dynamic recrystallization, were determined based on the alloy strain hardening rate. The critical stress related to the onset of dynamic recrystallization decreases with temperature. The evolution of DRX microstructure strongly depends on the deformation temperature and the strain rate. Dynamic recrystallization appears at high temperatures and low strain rates. The addition of Y can refine the grain and effectively accelerate dynamic recrystallization. Dislocation generation and multiplication are the main hot deformation mechanisms for the alloy. The deformation temperature increase and the strain rate decrease can promote dynamic recrystallization of the alloy.

Effects of heat treating PM Rene' 95 slightly below the gamma-prime solvus

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.

1977-01-01

An investigation was performed on As-HIP Rene' 95 to obtain additional information on the variation of the amount of gamma-prime with solutioning temperatures near the gamma-prime solvus temperature and the resulting effects on tensile and stress rupture strengths of As-HIP Rene' 95. The amount of gamma-prime phase was found to increase at a rate of about 0.5% per degree Celsius as the temperature decreased from the solvus temperature to about 50 C below the gamma-prime solvus temperature. The change in the amount of gamma-prime phase with decreasing solutioning temperature was observed to be primarily associated with decreasing solubilities of Al+Ti+Nb and increasing solubility of Cr in the gamma phase. For As-HIP Rene' 95 solutioned at either 1107 or 1135 C and subsequently water-quenched and double aged for 4 hours at 815 C followed by 24 hours at 650 C, the higher solution temperature resulted in significantly greater yield strengths at room temperature and 650 C as well as a greater room-temperature ultimate strength. Also, longer stress rupture lives at 650 C were associated with the higher solution temperature.

The Effect of Curing Temperature on the Properties of Cement Pastes Modified with TiO2 Nanoparticles

PubMed Central

Pimenta Teixeira, Karine; Perdigão Rocha, Isadora; De Sá Carneiro, Leticia; Flores, Jessica; Dauer, Edward A.; Ghahremaninezhad, Ali

2016-01-01

This paper investigates the effect of curing temperature on the hydration, microstructure, compressive strength, and transport of cement pastes modified with TiO2 nanoparticles. These characteristics of cement pastes were studied using non-evaporable water content measurement, X-ray diffraction (XRD), compressive strength test, electrical resistivity and porosity measurements, and scanning electron microscopy (SEM). It was shown that temperature enhanced the early hydration. The cement pastes cured at elevated temperatures generally showed an increase in compressive strength at an early age compared to the cement paste cured at room temperature, but the strength gain decreased at later ages. The electrical resistivity of the cement pastes cured at elevated temperatures was found to decrease more noticeably at late ages compared to that of the room temperature cured cement paste. SEM examination indicated that hydration product was more uniformly distributed in the microstructure of the cement paste cured at room temperature compared to the cement pastes cured at elevated temperatures. It was observed that high temperature curing decreased the compressive strength and electrical resistivity of the cement pastes at late ages in a more pronounced manner when higher levels of TiO2 nanoparticles were added. PMID:28774073

SPH investigation of the thermal effects on the fluid mixing in a microchannel with rotating stirrers

NASA Astrophysics Data System (ADS)

Shamsoddini, Rahim

2018-04-01

An incompressible smoothed particle hydrodynamics algorithm is proposed to model and investigate the thermal effect on the mixing rate of an active micromixer in which the rotating stirrers enhance the mixing rate. In liquids, mass diffusion increases with increasing temperature, while viscosity decreases; so, the local Schmidt number decreases considerably with increasing temperature. The present study investigates the effect of wall temperature on mixing rate with an improved SPH method. The robust SPH method used in the present work is equipped with a shifting algorithm and renormalization tensors. By introducing this new algorithm, the several mass, momentum, energy, and concentration equations are solved. The results, discussed for different temperature ratios, show that mixing rate increases significantly with increased temperature ratio.

Effect of Controlled Rolling and Cooling On Microstructure and Mechanical Properties of 30crmnti Wire Rod

NASA Astrophysics Data System (ADS)

Ruan, Shipeng; Dong, Qing; Zhang, Lei; Wang, Lijun

2017-09-01

The effect of controlled rolling and cooling on microstructure and mechanical properties of alloy structure steel 30CrMnTi wire rod with diameter 6.5mm was studied. The results show that the lower finish rolling temperature resulted in a decrease in tensile strength but an increase in elongation and reduction of area. When the finish rolling temperature decreases from 950°C to 850°C, the tensile strength value decreases from 750MPa to 660MPa, and the elongation increases from 21% to 30%, the reduction of area increases from 64% to 71%. The grain size also refines from 20μm to 9.9μm when the finish rolling temperature decreases from 950°C to 850°C. The decrease of tensile strength is due to the change of microstructure which evolved from more bainite to ferrite and pearlite.

The Effect of Heat Stress on Tomato Pollen Characteristics is Associated with Changes in Carbohydrate Concentration in the Developing Anthers

PubMed Central

PRESSMAN, ETAN; PEET, MARY M.; PHARR, D. MASON

2002-01-01

Continuous exposure of tomato ‘Trust’ to high temperatures (day/night temperatures of 32/26 °C) markedly reduced the number of pollen grains per flower and decreased viability. The effect of heat stress on pollen viability was associated with alterations in carbohydrate metabolism in various parts of the anther during its development. Under control, favourable temperature conditions (28/22 °C), starch accumulated in the pollen grains, where it reached a maximum value 3 d before anthesis; it then diminished towards anthesis. During anther development, the concentration of total soluble sugars gradually increased in the anther walls and in the pollen grains (but not in the locular fluid), reaching a maximum at anthesis. Continuous exposure of the plants to high temperatures (32/26 °C) prevented the transient increase in starch concentration and led to decreases in the concentrations of soluble sugars in the anther walls and the pollen grains. In the locular fluid, however, a higher soluble sugar concentration was detected under the high‐temperature regime throughout anther development. These results suggest that a major effect of heat stress on pollen development is a decrease in starch concentration 3 d before anthesis, which results in a decreased sugar concentration in the mature pollen grains. These events possibly contribute to the decreased pollen viability in tomato. PMID:12466104

Electrical characteristics and density of states of thin-film transistors based on sol-gel derived ZnO channel layers with different annealing temperatures

NASA Astrophysics Data System (ADS)

Wang, S.; Mirkhani, V.; Yapabandara, K.; Cheng, R.; Hernandez, G.; Khanal, M. P.; Sultan, M. S.; Uprety, S.; Shen, L.; Zou, S.; Xu, P.; Ellis, C. D.; Sellers, J. A.; Hamilton, M. C.; Niu, G.; Sk, M. H.; Park, M.

2018-04-01

We report on the fabrication and electrical characterization of bottom gate thin-film transistors (TFTs) based on a sol-gel derived ZnO channel layer. The effect of annealing of ZnO active channel layers on the electrical characteristics of the ZnO TFTs was systematically investigated. Photoluminescence (PL) spectra indicate that the crystal quality of the ZnO improves with increasing annealing temperature. Both the device turn-on voltage (Von) and threshold voltage (VT) shift to a positive voltage with increasing annealing temperature. As the annealing temperature is increased, both the subthreshold slope and the interfacial defect density (Dit) decrease. The field effect mobility (μFET) increases with annealing temperature, peaking at 800 °C and decreases upon further temperature increase. An improvement in transfer and output characteristics was observed with increasing annealing temperature. However, when the annealing temperature reaches 900 °C, the TFTs demonstrate a large degradation in both transfer and output characteristics, which is possibly produced by non-continuous coverage of the film. By using the temperature-dependent field effect measurements, the localized sub-gap density of states (DOSs) for ZnO TFTs with different annealing temperatures were determined. The DOSs for the subthreshold regime decrease with increasing annealing temperature from 600 °C to 800 °C and no substantial change was observed with further temperature increase to 900 °C.

Various anti-motion sickness drugs and core body temperature changes.

PubMed

Cheung, Bob; Nakashima, Ann M; Hofer, Kevin D

2011-04-01

Blood flow changes and inactivity associated with motion sickness appear to exacerbate the rate of core temperature decrease during subsequent body cooling. We investigated the effects of various classes of anti-motion sickness drugs on core temperature changes. There were 12 healthy male and female subjects (20-35 yr old) who were given selected classes of anti-motion sickness drugs prior to vestibular Coriolis cross coupling induced by graded yaw rotation and periodic pitch-forward head movements in the sagittal plane. All subjects were then immersed in water at 18 degrees C for a maximum of 90 min or until their core temperature reached 35 degrees C. Double-blind randomized trials were administered, including a placebo, a non-immersion control with no drug, and six anti-motion sickness drugs: meclizine, dimenhydrinate, chlorpheniramine, promethazine + dexamphetamine, promethazine + caffeine, and scopolamine + dexamphetamine. A 7-d washout period was observed between trials. Core temperature and the severity of sickness were monitored throughout each trial. A repeated measures design was performed on the severity of sickness and core temperature changes prior to motion provocation, immediately after the motion sickness end point, and throughout the period of cold-water immersion. The most effective anti-motion sickness drugs, promethazine + dexamphetamine (with a sickness score/duration of 0.65 +/- 0.17) and scopolamine + dexamphetamine (with a sickness score/duration of 0.79 +/- 0.17), significantly attenuated the decrease in core temperature. The effect of this attenuation was lower in less effective drugs. Our results suggest that the two most effective anti-motion sickness drugs are also the most effective in attenuating the rate of core temperature decrease.

Pyrolysis temperature influences ameliorating effects of biochars on acidic soil.

PubMed

Wan, Qing; Yuan, Jin-Hua; Xu, Ren-Kou; Li, Xing-Hui

2014-02-01

The biochars were prepared from straws of canola, corn, soybean, and peanut at different temperatures of 300, 500, and 700 °C by means of oxygen-limited pyrolysis.Amelioration effects of these biochars on an acidic Ultisol were investigated with incubation experiments, and application rate of biochars was 10 g/kg. The incorporation of these biochars induced the increase in soil pH, soil exchangeable base cations, base saturation, and cation exchange capacity and the decrease in soil exchangeable acidity and exchangeable Al. The ameliorating effects of biochars on acidic soil increased with increase in their pyrolysis temperature. The contribution of oxygen-containing functional groups on the biochars to their ameliorating effects on the acidic soil decreased with the rise in pyrolysis temperature, while the contribution from carbonates in the biochars changed oppositely. The incorporation of the biochars led to the decrease in soil reactive Al extracted by 0.5mol/L CuCl2, and the content of reactive Al was decreased with the increase in pyrolysis temperature of incorporated biochars. The biochars generated at 300 °C increased soil organically complexed Al due to ample quantity of oxygen-containing functional groups such as carboxylic and phenolic groups on the biochars, while the biochars generated at 500 and 700 °C accelerated the transformation of soil exchangeable Al to hydroxyl-Al polymers due to hydrolysis of Al at higher pH. Therefore, the crop straw-derived biochars can be used as amendments for acidic soils and the biochars generated at relatively high temperature have great ameliorating effects on the soils.

Electrical properties of granite with implications for the lower crust.

USGS Publications Warehouse

Olhoeft, G.R.

1981-01-01

The electrical properties of granite appear to be dominantly controlled by the amount of free water in the granite and by temperature. Minor contributions to the electrical properties are provided by hydrostatic and lithostatic pressure, structurally bound water, oxygen fugacity, and other parameters. The effect of sulphur fugacity may be important but is experimentally unconfirmed. In addition to changing the magnitude of electrical properties, the amount and chemistry of water in granite significantly changes the temperature dependence of the electrical properties. With increasing temperature, changes in water content retain large, but lessened, effects on electrical properties. Near room temperature, a monolayer of water will decrease the electrical resistivity by an order of magnitude. Several weight-percent water may decrease the electrical resistivity by as much as nine orders of magnitude and decrease the thermal activation energy by a factor of five. At elevated temperatures just below granitic melting, a few weight-percent water may still decrease the resistivity by as much as 3 orders of magnitude and the activation energy by a factor of two.-Author

The Effects of Temperature and CO2-induced Acidification on Skeletal Morphology of the Tropical Reef-building Coral Siderastrea siderea

NASA Astrophysics Data System (ADS)

Cobleigh, K.

2016-02-01

Coral reefs are threatened by increasing sea surface temperatures and decreasing surface seawater pH. Although numerous experimental studies have examined the effects of these global scale stressors on corals, few have quantified the effects of temperature and acidification on coral skeletal morphology. We conducted controlled laboratory experiments to investigate the effects of temperature (25, 28, 32°C) and CO2-induced ocean acidification (pCO2 = 324, 477, 604, 2553 µatm) on skeletal morphology of the highly resilient Caribbean reef-building coral Siderastrea siderea over a 95-day interval. Post-treatment S. siderea corallites from nearshore, backreef, and forereef colonies were imaged via stereo microscopy to evaluate impact of warming and acidification on corallite height and infilling. Both an increase and decrease in temperature relative to the control (i.e., near-present-day temperatures) resulted in increased corallite height but decreased skeletal infilling. In contrast, corals reared under the lowest (i.e., pre-industrial) and highest pCO2 treatments (i.e., extreme pCO2) exhibited both decreased corallite height and skeletal infilling relative to the control. We observed no difference in corallite height or infilling across reef zones, either within or across treatments. Interestingly, the warming projected for the end of the 21st century (32°C) resulted in increased corallite height and reduced corallite infilling. Acidification projected for the same interval (pCO2 = 604 µatm) also resulted in increased corallite height and decreased infilling. Collectively, our results suggest that these two global stressors will result in S. siderea corallites that are taller yet less infilled by the end of the 21st century. Changes in S. siderea arising from warming and acificiation may exacerbate observed declines in coral health across Caribbean reef systems.

Temperature Dependent Effects of Elevated CO2 on Shell Composition and Mechanical Properties of Hydroides elegans: Insights from a Multiple Stressor Experiment

PubMed Central

Chan, Vera B. S.; Thiyagarajan, Vengatesen; Lu, Xing Wen; Zhang, Tong; Shih, Kaimin

2013-01-01

The majority of marine benthic invertebrates protect themselves from predators by producing calcareous tubes or shells that have remarkable mechanical strength. An elevation of CO2 or a decrease in pH in the environment can reduce intracellular pH at the site of calcification and thus interfere with animal’s ability to accrete CaCO3. In nature, decreased pH in combination with stressors associated with climate change may result in the animal producing severely damaged and mechanically weak tubes. This study investigated how the interaction of environmental drivers affects production of calcareous tubes by the serpulid tubeworm, Hydroides elegans. In a factorial manipulative experiment, we analyzed the effects of pH (8.1 and 7.8), salinity (34 and 27‰), and temperature (23°C and 29°C) on the biomineral composition, ultrastructure and mechanical properties of the tubes. At an elevated temperature of 29°C, the tube calcite/aragonite ratio and Mg/Ca ratio were both increased, the Sr/Ca ratio was decreased, and the amorphous CaCO3 content was reduced. Notably, at elevated temperature with decreased pH and reduced salinity, the constructed tubes had a more compact ultrastructure with enhanced hardness and elasticity compared to decreased pH at ambient temperature. Thus, elevated temperature rescued the decreased pH-induced tube impairments. This indicates that tubeworms are likely to thrive in early subtropical summer climate. In the context of climate change, tubeworms could be resilient to the projected near-future decreased pH or salinity as long as surface seawater temperature rise at least by 4°C. PMID:24265732

Effect of Air Temperature and Relative Humidity at Various Fuel-Air Ratios on Exhaust Emissions on a Per-Mode Basis of an AVCO Lycoming 0-320 Diad Light Aircraft Engine: Volume 1: Results and Plotted Data

NASA Technical Reports Server (NTRS)

Skorobatckyi, M.; Cosgrove, D. V.; Meng, P. R.; Kempe, E. E., Jr.

1978-01-01

A carbureted four cylinder air cooled 0-320 DIAD Lycoming aircraft engine was tested to establish the effects of air temperature and humidity at various fuel-air ratios on the exhaust emissions on a per-mode basis. The test conditions include carburetor lean out at air temperatures of 50, 59, 80, and 100 F at relative humidities of 0, 30, 60, and 80 percent. Temperature humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased. Even at a fixed fuel air ratio, the HC emissions increase and the NOx emissions decrease at the higher values of air temperature and humidity.

Effect of air temperature and relative humidity at various fuel-air ratios on exhaust emissions on a per-mode basis of an Avco Lycoming 0-320 DIAD light aircraft engine. Volume 2: Individual data points

NASA Technical Reports Server (NTRS)

Skorobatckyi, M.; Cosgrove, D. V.; Meng, P. R.; Kempke, E. R.

1976-01-01

A carbureted four cylinder air cooled 0-320 DIAD Lycoming aircraft engine was tested to establish the effects of air temperature and humidity at various fuel-air ratios on the exhaust emissions on a per-mode basis. The test conditions included carburetor lean-out at air temperatures of 50, 59, 80, and 100 F at relative humidities of 0, 30, 60, and 80 percent. Temperature-humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased. Even at a fixed fuel-air ratio, the HC emissions increase and the NOx emissions decrease at the higher values of air temperature and humidity. Volume II contains the data taken at each of the individual test points.

Effect of temperature on the formation of creep substructure in sodium chloride single crystals

NASA Technical Reports Server (NTRS)

Raj, Sai V.; Pharr, George M.

1992-01-01

The effect of temperature on the substructure morphology and the cell and subgrain size was investigated experimentally in NaCl single crystals under creep in the temperature range 573-873 K. It is found that the effect of temperature on the cell and subgrain sizes is weak in comparison with the effect of stress. However, there was a qualitative change in the substructure morphology with temperature, with the cells and subgrains better defined at higher temperatures. The volume fraction of the cell boundaries decreased with increasing temperature, thereby indicating a refinement of the microstructure at higher temperatures.

Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

PubMed

Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

2015-07-03

The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study. Copyright © 2015 Elsevier B.V. All rights reserved.

Simulation of human thermoregulation during water immersion: application to an aircraft cabin water-spray system.

PubMed

Wolf, M B; Garner, R P

1997-01-01

A model was developed of transient changes in metabolic heat production and core temperature for humans subjected to cold conditions. It was modified to predict thermal effects of the upper parts of the body being sprayed with water from a system designed to reduce the smoke effects of an airplane fire. Temperature changes were computed at 25 body segments in response to water immersion, cold-air exposure, and windy conditions. Inputs to the temperature controller were: (a) temperature change signals from skin segments and (b) an integrated signal of the product of skin and head-core (hypothalamic) temperature changes. The controller stimulated changes in blood flow to skin and muscle and heat production by shivering. Two controller parameters were adjusted to obtain good predictions of temperature and heat-production experimental data in head-out, water-immersion (0 degree-28 degrees C) studies in humans. A water layer on the skin whose thickness decreased transiently due to evaporation was added to describe the effects of the water-spray system. Because the layer evaporated rapidly in a very cold and windy environment, its additional cooling effect over a 60-min exposure period was minimal. The largest additional decrease in rectal temperature due to the water layer was < 1 degree C, which was in normal conditions where total decreases were small.

Cleavage fracture in pearlitic eutectoid steel

NASA Astrophysics Data System (ADS)

Alexander, D. J.; Bernstein, I. M.

1989-11-01

The effect of microstructure on flow and fracture properties of fully pearlitic steel has been studied by independently varying the prior austenite grain size and the pearlite interlamellar spacing through appropriate heat treatments. The yield strength is independent of the prior austenite grain size but increases as the interlamellar spacing or the temperature decreases. The microstructural dependence can be explained by using a model which assumes that yielding is controlled by dislocation motion in the ferrite lamellae. The critical tensile stress for cleavage fracture is found to be independent of prior austenite grain size, increasing as the interlamellar spacing decreases. The cleavage fracture stress is independent of temperature for fine pearlite but increases as the temperature decreases for coarse pearlite. The associated fracture in blunt notch specimens initiates at inclusions beneath notch surface near the location of maximum tensile stress. From the size of such inclusions, the effective surface energy for cleavage fracture can be directly calculated and is found to be independent of temperature and prior austenite grain size but to increase as the interlamellar spacing decreases, from about 5 to 13 J/m2 for the range of microstructures and temperatures used in this study. Additional measurements of the effective surface energy and further theoretical analyses of the cleavage process are needed.

Effect of processing conditions on the quality characteristics of barley chips.

PubMed

Prakash, Jyoti; Naik, H R; Hussain, Syed Zameer; Singh, Baljit

2015-01-01

The aim of the present study was to study the effect of lime concentration, frying temperature and frying time on quality characteristics of barley chips. Effect of salt concentration and packaging material on the quality and stability of the product was also studied during 180 days of storage under ambient conditions. An increase in fat content of chips was observed with the increase in lime concentration, frying temperature and time, whereas a decreasing trend was observed in moisture content of chips. An increase in amylose content of chips was observed during frying. However, it was found that the amylopectin in chips decreased during frying as frying temperature and time was increased. An increase in colour difference (ΔE) and crispness was noted in chips during frying as frying temperature and time increased. With the increase in lime concentration (0.5 and 1.0 %) both ΔE and break force of chips was found decreased. The results further revealed that there was gradual decrease in fat (%) and amylopectin (%) during storage, whereas moisture (%) and amylose (%) increased during storage period. Organoleptic evaluation of the product revealed that scores of colour, texture, flavour and over all acceptability decrease during storage. However the treatment (salt 2 % and aluminium based laminate) recorded better score with respect to colour, flavour, texture and overall acceptability.

Effects of high ambient temperature on urea-nitrogen recycling in lactating dairy cows.

PubMed

Obitsu, Taketo; Kamiya, Mitsuru; Kamiya, Yuko; Tanaka, Masahito; Sugino, Toshihisa; Taniguchi, Kohzo

2011-08-01

Effects of exposure to hot environment on urea metabolism were studied in lactating Holstein cows. Four cows were fed ad libitum a total mixed ration and housed in a temperature-controlled chamber at constant moderate (18°C) or high (28°C) ambient temperatures in a cross-over design. Urea nitrogen (N) kinetics was measured by determining urea isotopomer in urine after single injection of [(15) N(2) ]urea into the jugular vein. Both dry matter intake and milk yield were decreased under high ambient temperature. Intakes of total N and digestible N were decreased under high ambient temperature but urinary urea-N excretion was increased. The ratio of urea-N production to digestible N was increased, whereas the proportion of gut urea-N entry to urea-N production tended to be decreased under high ambient temperature. Neither return to the ornithine cycle, anabolic use nor fecal excretion of urea-N recycled to the gut was affected by ambient temperature. Under high ambient temperature, renal clearance of plasma urea was not affected but the gut clearance was decreased. Increase of urea-N production and reduction of gut urea-N entry, in relative terms, were associated with increased urinary urea-N excretion of lactating dairy cows in higher thermal environments. 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

Effects of water temperature on the mortality of field-collected fish marked with fluorescent pigment

USGS Publications Warehouse

Holland Bartels, L. E.; Dewey, M.R.; Zigler, S.J.

1989-01-01

The cumulative effects of collection, handling, and marking with fluorescent pigment on the mortality of adult minnows, young-of-the-year centrarchids, and large centrarchids and percids was determined at five water temperatures (10-20.6 degree C) in field trials. There have been few field trials of this type. The mortality of centrarchids and percids was directly related to temperature and decreased noticeably when the temperature was below 19.5 degree C. The mortality of minnows decreased somewhat as river temperatures cooled but was always at least 50%. Variation was high in the temperature-related patterns of mortality in different taxa and sizes of fish. This variation complicates the accuracy and usefulness of pigment in marking field-collected fish for mark-recapture studies in warmwater systems.

Effect of alcohol on behavioral and autonomic thermoregulation in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, C.J.; Stead, A.G.

1986-01-01

Male, BALB/c mice were injected intraperitoneally with ethyl alcohol (ethanol) in dosages of 0, 0.03, 0.1, 0.3, 1.0, or 3.0 g/kg and then placed in a temperature gradient that permitted the measurement of preferred ambient temperature (Ta). The 3 g/kg dosage of ethanol resulted in a slight lowering of the preferred Ta during the first 30 min of placement in the gradient. However, there was no overall statistically significant effect of alcohol dosage on preferred Ta. In another experiment, BALB/c mice were treated with the aforementioned ethanol dosages while metabolic rate (MR), evaporative water loss (EWL), and colonic temperature weremore » measured 60 min post-injection at Ta's of 20, 30, and 35 C a dosage of 3 g/kg caused a significant decrease in MR, EWL, and colonic temperature. At a Ta of 30 C this same dosage caused significant reduction in colonic temperature, however; at Ta of 35 C ethanol had no effect on these parameters. In spite of the significant decrease in colonic temperature at a Ta of 30 C, which approximates the normal preferred Ta, the behavioral thermal preference was marginally affected. It is not clear whether or not ethanol injection results in a decrease in the set-point body temperature.« less

Fluid-electrolyte shifts and thermoregulation - Rest and work in heat with head cooling

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Van Beaumont, W.; Brock, P. J.; Montgomery, L. D.; Morse, J. T.; Shvartz, E.; Kravik, S.

1980-01-01

The effects of head cooling on thermoregulation and associated plasma fluid and electrolyte shifts during rest and submaximal exercise in the heat are investigated. Thermoregulatory responses and plasma volume were measured in four male subjects fitted with liquid-cooled neoprene headgear during 60 min of rest, 60 min of ergometer exercise at 45% maximal oxygen uptake and 30 min of recovery in the supine position at 40.1 C and 40% relative humidity. It is found that, compared to control responses, head cooling decreased thigh sweating and increased mean skin temperature at rest and attenuated increases in thigh sweating, heart rate, rectal temperature and ventilation during exercise. During recovery, cooling is observed to facilitate decreases in sweat rate, heart rate, rectal temperature and forearm blood flow and enhance the increase in average temperature. Cooling had no effect on plasma protein, osmotic or electrolyte shifts, and decreased plasma volume losses. The findings indicate the effectiveness of moderate head cooling for the improvement of human performance during exercise in heat.

Volatile organic compound emissions during hot-pressing of southern pine particleboard : panel size effects and trade-off between press time and temperature

Treesearch

Wenlong Wang; Douglas J. Gardner; Melissa G.D. Baumann

2002-01-01

In previous research, it was shown that decreasing either press temperature or press time generally resulted in decreased volatile organic compound (VOC) emissions during the hot-pressing of southern pine particleboard. However, because it is impossible to reduce both pressing time and temperature while maintaining panel physical and mechanical properties, this study...

Thermopower of CexR1-xB6 (R=La, Pr and Nd)

NASA Astrophysics Data System (ADS)

Kim, Moo‑Sung; Nakai, Yuki; Tou, Hideki; Sera, Masafumi; Iga, Fumitoshi; Takabatake, Toshiro; Kunii, Satoru

2006-06-01

The thermopower, S, of CexR1-xB6 (R=La, Pr, Nd) was investigated. S with a positive sign shows a typical behavior observed in the Ce Kondo system, an increase with decreasing temperature at high temperatures and a maximum at low temperatures. The S values of all the systems at high temperatures are roughly linearly dependent on the Ce concentration, indicating the conservation of the single-impurity character of the Kondo effect in a wide x range. However, the maximum value of S, Smax, and the temperature, Tmax, at which Smax is observed exhibit different x dependences between CexLa1-xB6 and CexR1-xB6 (R=Pr, Nd). In CexLa1-xB6, Tmax, which is ˜8 K in CeB6, decreases with decreasing x and converges to ˜1 K in a very dilute alloy and Smax shows an increase below x ˜ 0.1 after decreasing with decreasing x. In CexR1-xB6 (R=Pr, Nd), Tmax shows a weak x dependence but Smax shows a roughly linear decrease in x. These results are discussed from the standpoint of the chemical pressure effect and the Ce-Ce interaction. S in the long-range ordered phase shows very different behaviors between CexPr1-xB6 and CexNd1-xB6.

Effects of Elevated CO2 and Temperature on Yield and Fruit Quality of Strawberry (Fragaria × ananassa Duch.) at Two Levels of Nitrogen Application

PubMed Central

Sun, Peng; Mantri, Nitin; Lou, Heqiang; Hu, Ya; Sun, Dan; Zhu, Yueqing; Dong, Tingting; Lu, Hongfei

2012-01-01

We investigated if elevated CO2 could alleviate the negative effect of high temperature on fruit yield of strawberry (Fragaria × ananassa Duch. cv. Toyonoka) at different levels of nitrogen and also tested the combined effects of CO2, temperature and nitrogen on fruit quality of plants cultivated in controlled growth chambers. Results show that elevated CO2 and high temperature caused a further 12% and 35% decrease in fruit yield at low and high nitrogen, respectively. The fewer inflorescences and smaller umbel size during flower induction caused the reduction of fruit yield at elevated CO2 and high temperature. Interestingly, nitrogen application has no beneficial effect on fruit yield, and this may be because of decreased sucrose export to the shoot apical meristem at floral transition. Moreover, elevated CO2 increased the levels of dry matter-content, fructose, glucose, total sugar and sweetness index per dry matter, but decreased fruit nitrogen content, total antioxidant capacity and all antioxidant compounds per dry matter in strawberry fruit. The reduction of fruit nitrogen content and antioxidant activity was mainly caused by the dilution effect of accumulated non-structural carbohydrates sourced from the increased net photosynthetic rate at elevated CO2. Thus, the quality of strawberry fruit would increase because of the increased sweetness and the similar amount of fruit nitrogen content, antioxidant activity per fresh matter at elevated CO2. Overall, we found that elevated CO2 improved the production of strawberry (including yield and quality) at low temperature, but decreased it at high temperature. The dramatic fluctuation in strawberry yield between low and high temperature at elevated CO2 implies that more attention should be paid to the process of flower induction under climate change, especially in fruits that require winter chilling for reproductive growth. PMID:22911728

CYTOGENETIC AND MOLECULAR RESPONSES OF AMMONIUM SULPHATE APPLICATION FOR TOLERANCE TO EXTREME TEMPERATURES IN VICIA FABA L.

PubMed

Öney, S; Tabur, S; Tuna, M

2015-01-01

Effects of ammonium sulphate [(NH4)2SO4] on mitosis, cell cycle and chromosomes in Vicia faba L. seeds exposed to extreme temperatures were investigated using flowcytometric and cytogenetic analysis. Seeds germinated at high and low temperatures showed a signiicant decrease in mitotic index as compared to those of optimum temperature conditions. Application of 50 and 1000 µM (NH4)2SO4 were successful in alleviating the negative effects of low and high temperature on mitotic activity, respectively. 50 µM (NH4)2SO4 showed the most positive effect on cell cycle at the extreme temperatures. This concentration increased the cell division removing or decreasing the negative effects of temperature stress. Namely, the highest G2/M and S phase percentages under stress conditions were obtained with application of 50 µM (NH4)2SO4. Chromosomal aberrations were not observed in cells of seeds germinated in distilled water and also at any temperatures. However, the frequency of chromosomal aberrations increased significantly by increasing (NH4)2SO4 concentration. The highest aberration frequency in all temperature degree tested was found at 1000 µM (NH4)2SO4 concentration.

Simultaneous effects of temperature and pressure on the donor binding energy in a V-groove quantum wire

NASA Astrophysics Data System (ADS)

Khordad, R.

2010-03-01

The influence of temperature and pressure, simultaneously, on the binding energy of a hydrogenic donor impurity in a ridge GaAs/Ga 1- xAl xAs quantum wire is studied using a variational procedure within the effective mass approximation. The subband energy and the binding energy of the donor impurity in its ground state as a function of the wire bend width and impurity location at different temperatures and pressures are calculated. The results show that, when the temperature increases, the donor binding energy decreases for a constant applied pressure for all wire bend widths. Also, the binding energy increases by increasing the pressure for a constant temperature for all wire bend widths. In addition, when the temperature and pressure are applied simultaneously the binding energy decreases as the quantum wire bend width increases. On the whole, it is deduced that the temperature and pressure have important effects on the donor binding energy in a V-groove quantum wire.

Thermal management improvement of an air-cooled high-power lithium-ion battery by embedding metal foam

NASA Astrophysics Data System (ADS)

Mohammadian, Shahabeddin K.; Rassoulinejad-Mousavi, Seyed Moein; Zhang, Yuwen

2015-11-01

Effect of embedding aluminum porous metal foam inside the flow channels of an air-cooled Li-ion battery module was studied to improve its thermal management. Four different cases of metal foam insert were examined using three-dimensional transient numerical simulations. The effects of permeability and porosity of the porous medium as well as state of charge were investigated on the standard deviation of the temperature field and maximum temperature inside the battery in all four cases. Compared to the case of no porous insert, embedding aluminum metal foam in the air flow channel significantly improved the thermal management of Li-ion battery cell. The results also indicated that, decreasing the porosity of the porous structure decreases both standard deviation of the temperature field and maximum temperature inside the battery. Moreover, increasing the permeability of the metal foam drops the maximum temperature inside the battery while decreasing this property leads to improving the temperature uniformity. Our results suggested that, among the all studied cases, desirable temperature uniformity and maximum temperature were achieved when two-third and the entire air flow channel is filled with aluminum metal foam, respectively.

Effects of temperature on nitrous oxide (N2O) emission from intensive aquaculture system.

PubMed

Paudel, Shukra Raj; Choi, Ohkyung; Khanal, Samir Kumar; Chandran, Kartik; Kim, Sungpyo; Lee, Jae Woo

2015-06-15

This study examines the effects of temperature on nitrous oxide (N2O) emissions in a bench-scale intensive aquaculture system rearing Koi fish. The water temperature varied from 15 to 24 °C at interval of 3 °C. Both volumetric and specific rate for nitrification and denitrification declined as the temperature decreased. The concentrations of ammonia and nitrite, however, were lower than the inhibitory level for Koi fish regardless of temperature. The effects of temperature on N2O emissions were significant, with the emission rate and emission factor increasing from 1.11 to 1.82 mg N2O-N/d and 0.49 to 0.94 mg N2O-N/kg fish as the temperature decreased from 24 to 15 °C. A global map of N2O emission from aquaculture was established by using the N2O emission factor depending on temperature. This study demonstrates that N2O emission from aquaculture is strongly dependent on regional water temperatures as well as on fish production. Copyright © 2015 Elsevier B.V. All rights reserved.

Dissipative Dynamics of Enzymes

NASA Astrophysics Data System (ADS)

Ariyaratne, Amila; Wu, Chenhao; Tseng, Chiao-Yu; Zocchi, Giovanni

2014-11-01

We explore enzyme conformational dynamics at sub-Å resolution, specifically, temperature effects. The ensemble-averaged mechanical response of the folded enzyme is viscoelastic in the whole temperature range between the warm and cold denaturation transitions. The dissipation parameter γ of the viscoelastic description decreases by a factor of 2 as the temperature is raised from 10 to 45 °C ; the elastic parameter K shows a similar decrease. Thus, when probed dynamically, the enzyme softens for increasing temperature. Equilibrium mechanical experiments with the DNA spring (and a different enzyme) also show, qualitatively, a small softening for increasing temperature.

Dissipative Dynamics of Enzymes

NASA Astrophysics Data System (ADS)

Ariyaratne, Amila; Wu, Chenhao; Tseng, Chiao-Yu; Zocchi, Giovanni; Zocchi LabMolecular Biophysics Team

2015-03-01

We explore enzyme conformational dynamics at sub - Å resolution, specifically temperature effects. The ensemble averaged mechanical response of the folded enzyme is viscoelastic in the whole temperature range between the warm and cold denaturation transitions. The dissipation parameter γ of the viscoelastic description decreases by a factor 2 as the temperature is raised from 10 C to 45 C; the elastic parameter K shows a similar decrease. Thus when probed dynamically, the enzyme softens for increasing temperature. Equilibrium mechanical experiments with the DNA spring (and a different enzyme) also show, qualitatively, a small softening for increasing temperature.

Dissipative dynamics of enzymes.

PubMed

Ariyaratne, Amila; Wu, Chenhao; Tseng, Chiao-Yu; Zocchi, Giovanni

2014-11-07

We explore enzyme conformational dynamics at sub-Å resolution, specifically, temperature effects. The ensemble-averaged mechanical response of the folded enzyme is viscoelastic in the whole temperature range between the warm and cold denaturation transitions. The dissipation parameter γ of the viscoelastic description decreases by a factor of 2 as the temperature is raised from 10 to 45 °C; the elastic parameter K shows a similar decrease. Thus, when probed dynamically, the enzyme softens for increasing temperature. Equilibrium mechanical experiments with the DNA spring (and a different enzyme) also show, qualitatively, a small softening for increasing temperature.

Temperature-dependent residual shear strength characteristics of smectite-bearing landslide soils

NASA Astrophysics Data System (ADS)

Shibasaki, Tatsuya; Matsuura, Sumio; Hasegawa, Yoichi

2017-02-01

This paper presents experimental investigations regarding the effect of temperature on the residual strength of landslide soils at slow-to-moderate shearing velocities. We performed ring-shear tests on 23 soil samples at temperatures of 6-29°C. The test results show that the shear strength of smectite-rich soils decreased when temperatures were relatively low. These positive temperature effects (strength losses at lower temperatures) observed for smectite-bearing soils are typical under relatively slow shearing rates. In contrast, under relatively high shearing rates, strength was gained as temperature decreased. As rheological properties of smectite suspensions are sensitive to environmental factors, such as temperature, pH, and dissolved ions, we inferred that temperature-dependent residual strengths of smectitic soils are also attributed to their specific rheological properties. Visual and scanning electron microscope observations of Ca-bentonite suggest that slickensided shear surfaces at slow shearing rates are very shiny and smooth, whereas those at moderate shearing rates are not glossy and are slightly turbulent, indicating that platy smectite particles are strongly orientated at slow velocities. The positive temperature effect is probably due to temperature-dependent microfriction that is mobilized in the parallel directions of the sheet structure of hydrous smectite particles. On the contrary, the influence of microviscous resistance, which appears in the vertical directions of the lamination, is assumed to increase at faster velocities. Our results imply that if slip-surface soils contain high fractions of smectite, decreases in ground temperature can lead to lowered shear resistance of the slip surface and trigger slow landslide movement.

Effect of Ni Addition on Bainite Transformation and Properties in a 2000 MPa Grade Ultrahigh Strength Bainitic Steel

NASA Astrophysics Data System (ADS)

Tian, Junyu; Xu, Guang; Jiang, Zhengyi; Hu, Haijiang; Zhou, Mingxing

2018-05-01

The effects of Nickle (Ni) addition on bainitic transformation and property of ultrahigh strength bainitic steels are investigated by three austempering processes. The results indicate that Ni addition hinders the isothermal bainite transformation kinetics, and decreases the volume fraction of bainite due to the decrease of chemical driving force for nucleation and growth of bainite transformation. Moreover, the product of tensile strength and total elongation (PSE) of high carbon bainitic steels decreases with Ni addition at higher austempering temperatures (220 and 250 °C), while it shows no significant difference at lower austempering temperature (200 °C). For the same steel (Ni-free or Ni-added steel), the amounts of bainite and RA firstly increase and then decrease with the increase of the austempering temperature, resulting in the highest PSE in the sample austempered at temperature of 220 °C. In addition, the effects of austempering time on bainite amount and property of high carbon bainitic steels are also analyzed. It indicates that in a given transformation time range of 30 h, more volume of bainite and better mechanical property in high carbon bainitic steels can be obtained by increasing the isothermal transformation time.

Effects of Fuel Temperature on Injection Process and Combustion of Dimethyl Ether Engine.

PubMed

Guangxin, Gao; Zhulin, Yuan; Apeng, Zhou; Shenghua, Liu; Yanju, Wei

2013-12-01

To investigate the effects of fuel temperature on the injection process in the fuel-injection pipe and the combustion characteristics of compression ignition (CI) engine, tests on a four stroke, direct injection dimethyl ether (DME) engine were conducted. Experimental results show that as the fuel temperature increases from 20 to 40 °C, the sound speed is decreased by 12.2%, the peak line pressure at pump and nozzle sides are decreased by 7.2% and 5.6%, respectively. Meanwhile, the injection timing is retarded by 2.2 °CA and the injection duration is extended by 0.8 °CA. Accordingly, the ignition delay and the combustion duration are extended by 0.7 °CA and 4.0 °CA, respectively. The cylinder peak pressure is decreased by 5.4%. As a result, the effective thermal efficiency is decreased, especially for temperature above 40 °C. Before beginning an experiment, the fuel properties of DME, including the density, the bulk modulus, and the sound speed were calculated by "ThermoData." The calculated result of sound speed is consistent with the experimental results.

Effect of temperature rise and hydrostatic pressure on microbending loss and refractive index change in double-coated optical fiber

NASA Astrophysics Data System (ADS)

Seraji, Faramarz E.; Toutian, Golnoosh

This paper presents an analysis of the effect of temperature rise and hydrostatic pressure on microbending loss, refractive index change, and stress components of a double-coated optical fiber by considering coating material parameters such as Young's modulus and the Poisson ratio. It is shown that, when temperature rises, the microbending loss and refractive index changes would decrease with increase of thickness of primary coating layer and will increase after passing through a minima. Increase of thickness of secondary coating layer causes the microbending loss and refractive index changes to decrease. We have shown that the temperature rise affecting the fiber makes the microbending loss and refractive index decrease, linearly. At a particular temperature, the microbending loss takes negative values, due to tensile pressure applied on the fiber. The increase of Young's modulus and the Poisson ratio of primary coating would lower the microbending loss and refractive index change whereas in the secondary coating layer, the condition reverses.

Effect of Structural Parameters on the Combustion Performance of Platelet Engines

NASA Astrophysics Data System (ADS)

Liang, Yin; Liu, Weiqiang

2017-12-01

Numerical simulation was adopted to determine its flow and combustion characteristics by using gaseous methane and oxygen as the main propellants, the effects of nozzle space and expanding angle are examined for the single element splash platelet injector. Navier-Stokes (N-S) equations were solved for the gas-gas flow field with a reduced mechanism involving 9 species and 1 reaction. Results indicated that large corner recirculation zones are produced in the combustor head. This phenomenon consequently enhances mixing and stabilizes combustion, but non-uniformity in temperature contour is observed in the combustor head. Recirculation zone decreases as nozzle space increases, which induces the decrease of maximum temperature and high temperature regions, but it has little influence on the combustion efficiency and combustion length. The combustion length and maximum temperature decrease initially and then increase as expanding angle increases. Conversely, a D value of 2.4 mm and γ value of 60° are selected for the future works because of the shortest combustion length and minimum temperature of the injector faceplate.

In vitro and in vivo assessment of the effect of initial moisture content and drying temperature on the feeding value of maize grain.

PubMed

Huart, F; Malumba, P; Odjo, S; Al-Izzi, W; Béra, F; Beckers, Y

2018-06-11

1. This study assessed the impact of drying temperature (54, 90, and 130°C) and maize grain moisture content at harvest (36% and 29%) on in vitro digestibility, the growth performance and ileal digestibility of broiler chickens. 2. In contrast to the results from the in vitro digestibility, apparent ileal digestibility of starch and energy decreased when the drying temperature was raised from 54 to 130°C, and this effect was more pronounced in maize grain harvested at high initial moisture content (36%). Ileal protein digestibility of maize grain decreased significantly when dried at the intermediate temperature (90°C) and with a high harvest moisture content (36%). Drying temperature and initial moisture content did not significantly affect AMEn. 3. When maize was dried at 130°C, the particle sizes of flour recovered after standard milling procedures decreased significantly, which would influence animal growth performance and in vivo digestibility through animal feed selection.

Microstructures and Mechanical Properties of Inconel 718 Alloy at Ultralow Temperatures

NASA Astrophysics Data System (ADS)

Yao, C. G.; Lv, H. J.; Yi, D. Q.; Meng, S.; Xiao, L. R.; Wang, B.

2018-04-01

The microstructures and mechanical properties of powder metallurgy Inconel 718 alloy were investigated in the temperatures range between 25 and - 253 °C. Tensile strength increased with the decrease in temperature, while the ductility first increased and then decreased. There was no significant change in impact toughness. When the temperature was - 253 °C, a zigzag stress-strain curve was observed for the alloy, owing to the interaction of dislocation glide and twinning, which effectively maintained the relatively good ductility.

Microstructures and Mechanical Properties of Inconel 718 Alloy at Ultralow Temperatures

NASA Astrophysics Data System (ADS)

Yao, C. G.; Lv, H. J.; Yi, D. Q.; Meng, S.; Xiao, L. R.; Wang, B.

2018-05-01

The microstructures and mechanical properties of powder metallurgy Inconel 718 alloy were investigated in the temperatures range between 25 and - 253 °C. Tensile strength increased with the decrease in temperature, while the ductility first increased and then decreased. There was no significant change in impact toughness. When the temperature was - 253 °C, a zigzag stress-strain curve was observed for the alloy, owing to the interaction of dislocation glide and twinning, which effectively maintained the relatively good ductility.

Possible rainfall reduction through reduced surface temperatures due to overgrazing

NASA Technical Reports Server (NTRS)

Otterman, J.

1975-01-01

Surface temperature reduction in terrain denuded of vegetation (as by overgrazing) is postulated to decrease air convection, reducing cloudiness and rainfall probability during weak meteorological disturbances. By reducing land-sea daytime temperature differences, the surface temperature reduction decreases daytime circulation of thermally driven local winds. The described desertification mechanism, even when limited to arid regions, high albedo soils, and weak meteorological disturbances, can be an effective rainfall reducing process in many areas including most of the Mediterranean lands.

Thermal management optimization of an air-cooled Li-ion battery module using pin-fin heat sinks for hybrid electric vehicles

NASA Astrophysics Data System (ADS)

Mohammadian, Shahabeddin K.; Zhang, Yuwen

2015-01-01

Three dimensional transient thermal analysis of an air-cooled module that contains prismatic Li-ion cells next to a special kind of aluminum pin fin heat sink whose heights of pin fins increase linearly through the width of the channel in air flow direction was studied for thermal management of Lithium-ion battery pack. The effects of pin fins arrangements, discharge rates, inlet air flow velocities, and inlet air temperatures on the battery were investigated. The results showed that despite of heat sinks with uniform pin fin heights that increase the standard deviation of the temperature field, using this kind of pin fin heat sink compare to the heat sink without pin fins not only decreases the bulk temperature inside the battery, but also decreases the standard deviation of the temperature field inside the battery as well. Increasing the inlet air temperature leads to decreasing the standard deviation of the temperature field while increases the maximum temperature of the battery. Furthermore, increasing the inlet air velocity first increases the standard deviation of the temperature field till reaches to the maximum point, and after that decreases. Also, increasing the inlet air velocity leads to decrease in the maximum temperature of the battery.

Strengthening Mechanisms in Thermomechanically Processed NbTi-Microalloyed Steel

NASA Astrophysics Data System (ADS)

Kostryzhev, Andrii G.; Marenych, Olexandra O.; Killmore, Chris R.; Pereloma, Elena V.

2015-08-01

The effect of deformation temperature on microstructure and mechanical properties was investigated for thermomechanically processed NbTi-microalloyed steel with ferrite-pearlite microstructure. With a decrease in the finish deformation temperature at 1348 K to 1098 K (1075 °C to 825 °C) temperature range, the ambient temperature yield stress did not vary significantly, work hardening rate decreased, ultimate tensile strength decreased, and elongation to failure increased. These variations in mechanical properties were correlated to the variations in microstructural parameters (such as ferrite grain size, solid solution concentrations, precipitate number density and dislocation density). Calculations based on the measured microstructural parameters suggested the grain refinement, solid solution strengthening, precipitation strengthening, and work hardening contributed up to 32 pct, up to 48 pct, up to 25 pct, and less than 3 pct to the yield stress, respectively. With a decrease in the finish deformation temperature, both the grain size strengthening and solid solution strengthening increased, the precipitation strengthening decreased, and the work hardening contribution did not vary significantly.

Interaction between neuronal nitric oxide synthase signaling and temperature influences sarcoplasmic reticulum calcium leak: role of nitroso-redox balance.

PubMed

Dulce, Raul A; Mayo, Vera; Rangel, Erika B; Balkan, Wayne; Hare, Joshua M

2015-01-02

Although nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results because of inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here, we show that temperature significantly modulates NO effects. To test the hypothesis that temperature profoundly affects nitroso-redox equilibrium, thereby affecting sarcoplasmic reticulum (SR) calcium (Ca(2+)) leak. We measured SR Ca(2+) leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (neuronal nitric oxide synthase-deficient mice-1 [NOS1(-/-)]), and hyper S-nitrosoglutathione reductase-deficient (GSNOR(-/-)) mice. In WT cardiomyocytes, SR Ca(2+) leak increased because temperature decreased from 37°C to 23°C, whereas in NOS1(-/-) cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR(-/-) cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1(-/-) cardiomyocytes; reducing leak at 37°C but increasing it at subphysiological temperatures. Oxypurinol and Tempol diminished the leak in NOS1(-/-) cardiomyocytes. Cooling from 37°C to 23°C increased reactive oxygen species generation in WT but decreased it in NOS1(-/-) cardiomyocytes. Oxypurinol further reduced reactive oxygen species generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca(2+) content in NOS1(-/-) cells but had no effect in WT or GSNOR(-/-). Ca(2+) leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating reactive oxygen species production because temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and reactive oxygen species which in turn has a major effect on SR Ca(2+). © 2014 American Heart Association, Inc.

Molecular Modeling for Calculation of Mechanical Properties of Epoxies with Moisture Ingress

NASA Technical Reports Server (NTRS)

Clancy, Thomas C.; Frankland, Sarah J.; Hinkley, J. A.; Gates, T. S.

2009-01-01

Atomistic models of epoxy structures were built in order to assess the effect of crosslink degree, moisture content and temperature on the calculated properties of a typical representative generic epoxy. Each atomistic model had approximately 7000 atoms and was contained within a periodic boundary condition cell with edge lengths of about 4 nm. Four atomistic models were built with a range of crosslink degree and moisture content. Each of these structures was simulated at three temperatures: 300 K, 350 K, and 400 K. Elastic constants were calculated for these structures by monitoring the stress tensor as a function of applied strain deformations to the periodic boundary conditions. The mechanical properties showed reasonably consistent behavior with respect to these parameters. The moduli decreased with decreasing crosslink degree with increasing temperature. The moduli generally decreased with increasing moisture content, although this effect was not as consistent as that seen for temperature and crosslink degree.

Electrical conductivity of high-purity germanium crystals at low temperature

NASA Astrophysics Data System (ADS)

Yang, Gang; Kooi, Kyler; Wang, Guojian; Mei, Hao; Li, Yangyang; Mei, Dongming

2018-05-01

The temperature dependence of electrical conductivity of single-crystal and polycrystalline high-purity germanium (HPGe) samples has been investigated in the temperature range from 7 to 100 K. The conductivity versus inverse of temperature curves for three single-crystal samples consist of two distinct temperature ranges: a high-temperature range where the conductivity increases to a maximum with decreasing temperature, and a low-temperature range where the conductivity continues decreasing slowly with decreasing temperature. In contrast, the conductivity versus inverse of temperature curves for three polycrystalline samples, in addition to a high- and a low-temperature range where a similar conductive behavior is shown, have a medium-temperature range where the conductivity decreases dramatically with decreasing temperature. The turning point temperature ({Tm}) which corresponds to the maximum values of the conductivity on the conductivity versus inverse of temperature curves are higher for the polycrystalline samples than for the single-crystal samples. Additionally, the net carrier concentrations of all samples have been calculated based on measured conductivity in the whole measurement temperature range. The calculated results show that the ionized carrier concentration increases with increasing temperature due to thermal excitation, but it reaches saturation around 40 K for the single-crystal samples and 70 K for the polycrystalline samples. All these differences between the single-crystal samples and the polycrystalline samples could be attributed to trapping and scattering effects of the grain boundaries on the charge carriers. The relevant physical models have been proposed to explain these differences in the conductive behaviors between two kinds of samples.

Observed Decrease of North American Winter Temperature Variability

NASA Astrophysics Data System (ADS)

Rhines, A. N.; Tingley, M.; McKinnon, K. A.; Huybers, P. J.

2015-12-01

There is considerable interest in determining whether temperature variability has changed in recent decades. Model ensembles project that extratropical land temperature variance will detectably decrease by 2070. We use quantile regression of station observations to show that decreasing variability is already robustly detectable for North American winter during 1979--2014. Pointwise trends from GHCND stations are mapped into a continuous spatial field using thin-plate spline regression, resolving small-scales while providing uncertainties accounting for spatial covariance and varying station density. We find that variability of daily temperatures, as measured by the difference between the 95th and 5th percentiles, has decreased markedly in winter for both daily minima and maxima. Composites indicate that the reduced spread of winter temperatures primarily results from Arctic amplification decreasing the meridional temperature gradient. Greater observed warming in the 5th relative to the 95th percentile stems from asymmetric effects of advection during cold versus warm days; cold air advection is generally from northerly regions that have experienced greater warming than western or southwestern regions that are generally sourced during warm days.

Effect of modification of isotactic polypropylene by additives of polyamide 6/66 on structural characteristics of composites

NASA Astrophysics Data System (ADS)

Vorontsov, N. V.; Popov, A. A.; Margolin, A. L.

2017-12-01

Changes in the supramolecular structure of polymer composites based on isotactic polypropylene (PP) and polyamide 6/66 (PA) are studied depending on the PP : PA ratio. Temperatures and enthalpies of melting and crystallization of both PP and PA and their composites are determined depending on the composition of the mixtures. It was shown that the initial melting point of a composite does not change with increasing PA content in the blends. The crystallization temperature of the mixtures is shown to increase with the addition of PA and becomes much higher than the crystallization temperatures of both PP and PA. The observed effect can be due to a strong interaction between the PP and PA molecules, thus decreasing the molecular mobility and increasing the crystallization temperature. The crystallization and melting of PP-PA mixtures are found to proceed at the close temperatures, although the crystallization and melting temperatures of pure PP and pure PA differ widely. The melting and crystallization enthalpies decrease with increasing PA concentration in the mixtures, which indicates a decrease in the degree of crystallinity of the composite.

Internal cooling of a lithium-ion battery using electrolyte as coolant through microchannels embedded inside the electrodes

NASA Astrophysics Data System (ADS)

Mohammadian, Shahabeddin K.; He, Ya-Ling; Zhang, Yuwen

2015-10-01

Two and three dimensional transient thermal analysis of a prismatic Li-ion cell has been carried out to compare internal and external cooling methods for thermal management of Lithium Ion (Li-ion) battery packs. Water and liquid electrolyte have been utilized as coolants for external and internal cooling, respectively. The effects of the methods on decreasing the temperature inside the battery and also temperature uniformity were investigated. The results showed that at the same pumping power, using internal cooling not only decreases the bulk temperature inside the battery more than external cooling, but also decreases the standard deviation of the temperature field inside the battery significantly. Finally, using internal cooling decreases the intersection angle between the velocity vector and the temperature gradient which according to field synergy principle (FSP) causes to increase the convection heat transfer.

Temperature and Strain-Rate Effects on Low-Cycle Fatigue Behavior of Alloy 800H

NASA Technical Reports Server (NTRS)

Rao, K. Bhanu Sankara; Schiffers, H.; Schuster, H.; Halford, G. R.

1996-01-01

The effects of strain rate (4 x 10(exp -6) to 4 x 10(exp -3)/s) and temperature on the Low-Cycle Fatigue (LCF) behavior of alloy 800H have been evaluated in the range 750 C to 950 C. Total axial strain controlled LCF tests were conducted in air at a strain amplitude of +/- 0.30 pct. LCF life decreased with decreasing strain rate and increasing temperature. The cyclic stress response behavior showed a marked variation with temperature and strain rate. The time- and temperature- dependent processes which influence the cyclic stress response and life have been identified and their relative importance assessed. Dynamic strain aging, time-dependent deformation, precipitation of parallel platelets of M(23)C6 on grain boundaries and incoherent ledges of twins, and oxidation were found to operate depending on the test conditions. The largest effect on life was shown by oxidation processes.

Experimental and theoretical investigation of temperature effects on an interbedded betavoltaic employing epitaxial Si and bidirectional (63)Ni.

PubMed

Liu, Yunpeng; Tang, Xiaobin; Xu, Zhiheng; Hong, Liang; Chen, Da

2014-12-01

The performance of an interbedded betavoltaic employing epitaxial Si and bidirectional (63)Ni was measured and calculated at various temperatures. The experimental results indicate that the temperature dependence of the performance of interbedded betavoltaics is similar to that of monolayer betavoltaics: Voc and Pmax decrease approximately linearly with increasing temperature at low temperatures of 213.15-253.15K and decrease exponentially with increasing temperature at high temperatures of 253.15-333.15K. However, the calculation results indicate that the temperature dependences of Voc and Pmax are always linear at both high and low temperatures. Isc increases slightly with increasing temperature in both experiment and calculation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of Temperature and Strain Rate on Tensile Deformation Behavior of 9Cr-0.5Mo-1.8W-VNb Ferritic Heat-Resistant Steel

NASA Astrophysics Data System (ADS)

Guo, Xiaofeng; Weng, Xiaoxiang; Jiang, Yong; Gong, Jianming

2017-09-01

A series of uniaxial tensile tests were carried out at different strain rate and different temperatures to investigate the effects of temperature and strain rate on tensile deformation behavior of P92 steel. In the temperature range of 30-700 °C, the variations of flow stress, average work-hardening rate, tensile strength and ductility with temperature all show three temperature regimes. At intermediate temperature, the material exhibited the serrated flow behavior, the peak in flow stress, the maximum in average work-hardening rate, and the abnormal variations in tensile strength and ductility indicates the occurrence of DSA, whereas the sharp decrease in flow stress, average work-hardening rate as well as strength values, and the remarkable increase in ductility values with increasing temperature from 450 to 700 °C imply that dynamic recovery plays a dominant role in this regime. Additionally, for the temperature ranging from 550 to 650 °C, a significant decrease in flow stress values is observed with decreasing in strain rate. This phenomenon suggests the strain rate has a strong influence on flow stress. Based on the experimental results above, an Arrhenius-type constitutive equation is proposed to predict the flow stress.

Investigation of Relationship between QBO and Ionospheric Neutral Temperature

NASA Astrophysics Data System (ADS)

Saǧır, Selçuk; Atıcı, Ramazan; Özcan, Osman

2016-07-01

The relationship between Quasi Biennial Oscillation (QBO) measured at 10 hPa altitude and neutral temperature obtained from NRLMSIS-00 model for 90 km altitude of ionosphere is statistically investigated. For this study, multiple-regression model is used. To see effect on neutral temperature of QBO directions, Dummy variables are added to model established. In the results of performed analysis, it is observed that QBO is effected on neutral temperature of ionosphere. It is determined that 57% of variations at neutral temperature can be explainable by QBO. According to the established model, statistical explainable ratio was determined as 1% that it is the highest rate. Also, it is seen that an increase/a decrease of 1 meter per second at QBO give rise to an increase/a decrease of 0,07 K at neutral temperature.

Effect of temperature and nutrients on the growth and development of seedlings of an invasive plant.

PubMed

Skálová, Hana; Moravcová, Lenka; Dixon, Anthony F G; Kindlmann, P; Pyšek, Petr

2015-04-28

Plant species distributions are determined by the response of populations to regional climates; however, little is known about how alien plants that arrive in central Europe from climatically warmer regions cope with the temperature conditions at the early stage of population development. Ambrosia artemisiifolia (common ragweed) is an invasive annual plant causing considerable health and economic problems in Europe. Although climate-based models predict that the whole of the Czech Republic is climatically suitable for this species, it is confined to the warmest regions. To determine the factors possibly responsible for its restricted occurrence, we investigated the effects of temperature and nutrient availability on its seedlings. The plants were cultivated at one of seven temperature regimes ranging from 10 to 34 °C, combined with three nutrient levels. The data on the rate of leaf development were used to calculate the lower developmental threshold (LDT, the temperature, in °C, below which development ceases), the sum of effective temperatures (SET, the amount of heat needed to complete a developmental stage measured in degree days above LDT) and width of the thermal window. The rate of development decreased with decrease in temperature and nutrient supply. Besides this, the decrease in the availability of nutrients resulted in decreased LDT, increased SET and wider thermal window. The dependence of LDT and SET on the availability of nutrients contradicts the concept that thermal constants do not vary. Our results highlight temperature as the main determinant of common ragweed's distribution and identify nutrient availability as a factor that results in the realized niche being smaller than the fundamental niche; both of these need to be taken into account when predicting the future spread of A. artemisiifolia. Published by Oxford University Press on behalf of the Annals of Botany Company.

Influence of perfusate temperature on nasal potential difference.

PubMed

Bronsveld, Inez; Vermeulen, François; Sands, Dorotha; Leal, Teresinha; Leonard, Anissa; Melotti, Paola; Yaakov, Yasmin; de Nooijer, Roel; De Boeck, Kris; Sermet, Isabelle; Wilschanski, Michael; Middleton, Peter G

2013-08-01

Nasal potential difference (NPD) quantifies abnormal ion transport in cystic fibrosis. It has gained acceptance as an outcome measure for the investigation of new therapies. To quantify the effect of solution temperature on NPD, we first examined the effect of switching from room temperature (20-25°C) to warmed (32-37°C) solutions and vice versa during each perfusion step. Secondly, standard protocols were repeated at both temperatures in the same subjects. Changing solution temperature did not alter NPD during perfusion with Ringer's solution (<1 mV) (p>0.1). During perfusion with zero chloride solution, changing from room temperature to warmed solutions tended to decrease absolute NPD (i.e. it became less negative) by 0.9 mV (p>0.1); changing from warmed to room temperature increased NPD by 2.1 mV (p<0.05). During isoprenaline perfusion, changing from room temperature to warmed solutions increased NPD by 1.5 mV (p<0.01) and from warmed to room temperature decreased NPD by 1.4 mV (p<0.05). For full protocols at room temperature or warmed in the same subjects, mean values were similar (n = 24). During warmed perfusion, group results for total chloride response had a larger standard deviation. As this increased variability will probably decrease the power of trials, this study suggests that solutions at room temperature should be recommended for the measurement of NPD.

Temperature dependent electrical properties of rare-earth metal Er Schottky contact on p-type InP

NASA Astrophysics Data System (ADS)

Rao, L. Dasaradha; Reddy, N. Ramesha; Kumar, A. Ashok; Reddy, V. Rajagopal

2013-06-01

The current-voltage (I-V) characteristics of the Er/p-InP Schottky barrier diodes (SBDs) have been investigated in the temperature range of 300-400K in steps of 25K. The electrical parameters such as ideality factor (n) and zero-bias barrier height (Φbo) are found to be strongly temperature dependent. It is observed that ΦI-V decreases whereas n increases with decreasing temperature. The series resistance is also calculated from the forward I-V characteristics of Er/p-InP SBD and it is found to be strongly dependent on temperature. Further, the temperature dependence of energy distribution of interface state density (NSS) profiles is determined from the forward I-V measurements by taking into account the bias dependence of the effective barrier height and ideality factor. It is observed that the NSS values increase with a decrease in temperature.

Temperature-driven regime shifts in the dynamics of size-structured populations.

PubMed

Ohlberger, Jan; Edeline, Eric; Vøllestad, Leif Asbjørn; Stenseth, Nils C; Claessen, David

2011-02-01

Global warming impacts virtually all biota and ecosystems. Many of these impacts are mediated through direct effects of temperature on individual vital rates. Yet how this translates from the individual to the population level is still poorly understood, hampering the assessment of global warming impacts on population structure and dynamics. Here, we study the effects of temperature on intraspecific competition and cannibalism and the population dynamical consequences in a size-structured fish population. We use a physiologically structured consumer-resource model in which we explicitly model the temperature dependencies of the consumer vital rates and the resource population growth rate. Our model predicts that increased temperature decreases resource density despite higher resource growth rates, reflecting stronger intraspecific competition among consumers. At a critical temperature, the consumer population dynamics destabilize and shift from a stable equilibrium to competition-driven generation cycles that are dominated by recruits. As a consequence, maximum age decreases and the proportion of younger and smaller-sized fish increases. These model predictions support the hypothesis of decreasing mean body sizes due to increased temperatures. We conclude that in size-structured fish populations, global warming may increase competition, favor smaller size classes, and induce regime shifts that destabilize population and community dynamics.

Mammographic film-processor temperature, development time, and chemistry: effect on dose, contrast, and noise.

PubMed

Kimme-Smith, C; Rothschild, P A; Bassett, L W; Gold, R H; Moler, C

1989-01-01

Six different combinations of film-processor temperature (33.3 degrees C, 35 degrees C), development time (22 sec, 44 sec), and chemistry (Du Pont medium contrast developer [MCD] and Kodak rapid process [RP] developer) were each evaluated by separate analyses with Hurter and Driffield curves, test images of plastic step wedges, noise variance analysis, and phantom images; each combination also was evaluated clinically. Du Pont MCD chemistry produced greater contrast than did Kodak RP chemistry. A change in temperature from 33.3 degrees C (92 degrees F) to 35 degrees C (95 degrees F) had the least effect on dose and image contrast. Temperatures of 36.7 degrees C (98 degrees F) and 38.3 degrees C (101 degrees F) also were tested with extended processing. The speed increased for 36.7 degrees C but decreased at 38.3 degrees C. Base plus fog increased, but contrast decreased for these higher temperatures. Increasing development time had the greatest effect on decreasing the dose required for equivalent film darkening when imaging BR12 breast equivalent test objects; ion chamber measurements showed a 32% reduction in dose when the development time was increased from 22 to 44 sec. Although noise variance doubled in images processed with the extended development time, diagnostic capability was not compromised. Extending the processing time for mammographic films was an effective method of dose reduction, whereas varying the processing temperature and chemicals had less effect on contrast and dose.

Effects of temperature on consumer-resource interactions.

PubMed

Amarasekare, Priyanga

2015-05-01

Understanding how temperature variation influences the negative (e.g. self-limitation) and positive (e.g. saturating functional responses) feedback processes that characterize consumer-resource interactions is an important research priority. Previous work on this topic has yielded conflicting outcomes with some studies predicting that warming should increase consumer-resource oscillations and others predicting that warming should decrease consumer-resource oscillations. Here, I develop a consumer-resource model that both synthesizes previous findings in a common framework and yields novel insights about temperature effects on consumer-resource dynamics. I report three key findings. First, when the resource species' birth rate exhibits a unimodal temperature response, as demonstrated by a large number of empirical studies, the temperature range over which the consumer-resource interaction can persist is determined by the lower and upper temperature limits to the resource species' reproduction. This contrasts with the predictions of previous studies, which assume that the birth rate exhibits a monotonic temperature response, that consumer extinction is determined by temperature effects on consumer species' traits, rather than the resource species' traits. Secondly, the comparative analysis I have conducted shows that whether warming leads to an increase or decrease in consumer-resource oscillations depends on the manner in which temperature affects intraspecific competition. When the strength of self-limitation increases monotonically with temperature, warming causes a decrease in consumer-resource oscillations. However, if self-limitation is strongest at temperatures physiologically optimal for reproduction, a scenario previously unanalysed by theory but amply substantiated by empirical data, warming can cause an increase in consumer-resource oscillations. Thirdly, the model yields testable comparative predictions about consumer-resource dynamics under alternative hypotheses for how temperature affects competitive and resource acquisition traits. Importantly, it does so through empirically quantifiable metrics for predicting temperature effects on consumer viability and consumer-resource oscillations, which obviates the need for parameterizing complex dynamical models. Tests of these metrics with empirical data on a host-parasitoid interaction yield realistic estimates of temperature limits for consumer persistence and the propensity for consumer-resource oscillations, highlighting their utility in predicting temperature effects, particularly warming, on consumer-resource interactions in both natural and agricultural settings. © 2014 The Author. Journal of Animal Ecology © 2014 British Ecological Society.

Equivalent circuit model parameters of a high-power Li-ion battery: Thermal and state of charge effects

NASA Astrophysics Data System (ADS)

Gomez, Jamie; Nelson, Ruben; Kalu, Egwu E.; Weatherspoon, Mark H.; Zheng, Jim P.

2011-05-01

Equivalent circuit model (EMC) of a high-power Li-ion battery that accounts for both temperature and state of charge (SOC) effects known to influence battery performance is presented. Electrochemical impedance measurements of a commercial high power Li-ion battery obtained in the temperature range 20 to 50 °C at various SOC values was used to develop a simple EMC which was used in combination with a non-linear least squares fitting procedure that used thirteen parameters for the analysis of the Li-ion cell. The experimental results show that the solution and charge transfer resistances decreased with increase in cell operating temperature and decreasing SOC. On the other hand, the Warburg admittance increased with increasing temperature and decreasing SOC. The developed model correlations that are capable of being used in process control algorithms are presented for the observed impedance behavior with respect to temperature and SOC effects. The predicted model parameters for the impedance elements Rs, Rct and Y013 show low variance of 5% when compared to the experimental data and therefore indicates a good statistical agreement of correlation model to the actual experimental values.

Effect of calcination temperatures on microstructures and photocatalytic activity of tungsten trioxide hollow microspheres.

PubMed

Yu, Jiaguo; Qi, Lifang; Cheng, Bei; Zhao, Xiufeng

2008-12-30

Tungsten trioxide hollow microspheres were prepared by immersing SrWO4 microspheres in a concentrated HNO3 solution, and then calcined at different temperatures. The prepared tungsten oxide samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, differential thermal analysis-thermogravimetry, UV-visible spectrophotometry, scanning electron microscopy, N2 adsorption/desorption measurements. The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. It was found that with increasing calcination temperatures, the average crystallite size and average pore size increased, on the contrary, Brunauer-Emmett-Teller-specific surface areas decreased. However, pore volume and porosity increased firstly, and then decreased. Increasing calcination temperatures resulted in the changes of surface morphology of hollow microspheres. The un-calcined and 300 degrees C-calcined samples showed higher photocatalytic activity than other samples. At 400 degrees C, the photocatalytic activity decreased greatly due to the decrease of specific surface areas. At 500 degrees C, the photocatalytic activity of the samples increased again due to the junction effect of two phases.

The effects of ambient temperature on cerebrovascular mortality: an epidemiologic study in four climatic zones in China

PubMed Central

2014-01-01

Background Little evidence is available about the association between temperature and cerebrovascular mortality in China. This study aims to examine the effects of ambient temperature on cerebrovascular mortality in different climatic zones in China. Method We obtained daily data on weather conditions, air pollution and cerebrovascular deaths from five cities (Beijing, Tianjin, Shanghai, Wuhan, and Guangzhou) in China during 2004-2008. We examined city-specific associations between ambient temperature and the cerebrovascular mortality, while adjusting for season, long-term trends, day of the week, relative humidity and air pollution. We examined cold effects using a 1°C decrease in temperature below a city-specific threshold, and hot effects using a 1°C increase in temperature above a city-specific threshold. We used a meta-analysis to summarize the cold and hot effects across the five cities. Results Beijing and Tianjin (with low mean temperature) had lower thresholds than Shanghai, Wuhan and Guangzhou (with high mean temperature). In Beijing, Tianjin, Wuhan and Guangzhou cold effects were delayed, while in Shanghai there was no or short induction. Hot effects were acute in all five cities. The cold effects lasted longer than hot effects. The hot effects were followed by mortality displacement. The pooled relative risk associated with a 1°C decrease in temperature below thresholds (cold effect) was 1.037 (95% confidence interval (CI): 1.020, 1.053). The pooled relative risk associated with a 1°C increase in temperature above thresholds (hot effect) was 1.014 (95% CI: 0.979, 1.050). Conclusion Cold temperatures are significantly associated with cerebrovascular mortality in China, while hot effect is not significant. People in colder climate cities were sensitive to hot temperatures, while people in warmer climate cities were vulnerable to cold temperature. PMID:24690204

Investigation of the deformation mechanisms of core-shell rubber-modified epoxy at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Brown, Hayley Rebecca

The industrial demand for high strength-to-weight ratio materials is increasing due to the need for high performance components. Epoxy polymers, although often used in fiber-reinforced polymeric composites, have an inherent low toughness that further decreases with decreasing temperatures. Second-phase additives have been effective in increasing the toughness of epoxies at room temperature; however, the mechanisms at low temperatures are still not understood. In this study, the deformation mechanisms of a DGEBA epoxy modified with MX960 core-shell rubber (CSR) particles were investigated under quasi-static tensile and impact loads at room temperature (RT) and liquid nitrogen (LN 2) temperature. Overall, the CSR had little effect on the tensile properties at RT and LN2 temperature. The impact strength decreased from neat to 3 wt% but increased from neat to 5 wt% at RT and LN2 temperature, with a higher impact strength at RT at all CSR loadings. The CSR particles debonded in front of the crack tip, inducing voids into the matrix. It was found that an increase in shear deformation and void growth likely accounted for the higher impact strength at 5 wt% CSR loading at RT while the thermal stress fields due to the coefficient of thermal expansion mismatch between rubber and epoxy and an increase in secondary cracking is likely responsible for the higher impact strength at 5 wt% tested at LN2 temperature. While a large toughening effect was not seen in this study, the mechanisms analyzed herein will likely be of use for further material investigations at cryogenic temperatures.

Ocean acidification alleviates low-temperature effects on growth and photosynthesis of the red alga Neosiphonia harveyi (Rhodophyta).

PubMed

Olischläger, Mark; Wiencke, Christian

2013-12-01

This study aimed to examine interactive effects between ocean acidification and temperature on the photosynthetic and growth performance of Neosiphonia harveyi. N. harveyi was cultivated at 10 and 17.5 °C at present (~380 µatm), expected future (~800 µatm), and high (~1500 µatm) pCO2. Chlorophyll a fluorescence, net photosynthesis, and growth were measured. The state of the carbon-concentrating mechanism (CCM) was examined by pH-drift experiments (with algae cultivated at 10 °C only) using ethoxyzolamide, an inhibitor of external and internal carbonic anhydrases (exCA and intCA, respectively). Furthermore, the inhibitory effect of acetazolamide (an inhibitor of exCA) and Tris (an inhibitor of the acidification of the diffusive boundary layer) on net photosynthesis was measured at both temperatures. Temperature affected photosynthesis (in terms of photosynthetic efficiency, light saturation point, and net photosynthesis) and growth at present pCO2, but these effects decreased with increasing pCO2. The relevance of the CCM decreased at 10 °C. A pCO2 effect on the CCM could only be shown if intCA and exCA were inhibited. The experiments demonstrate for the first time interactions between ocean acidification and temperature on the performance of a non-calcifying macroalga and show that the effects of low temperature on photosynthesis can be alleviated by increasing pCO2. The findings indicate that the carbon acquisition mediated by exCA and acidification of the diffusive boundary layer decrease at low temperatures but are not affected by the cultivation level of pCO2, whereas the activity of intCA is affected by pCO2. Ecologically, the findings suggest that ocean acidification might affect the biogeographical distribution of N. harveyi.

Seasonal changes in the cardiovascular, respiratory and metabolic responses to temperature and hypoxia in the bullfrog Rana catesbeiana.

PubMed

Rocha, P L; Branco, L G

1998-03-01

We assessed seasonal variations in the effects of temperature on hypoxia-induced alterations in the bullfrog Rana catesbeiana by measuring the heart rate, arterial blood pressure, breathing frequency, metabolic rate, blood gas levels, acid-base status and plasma glucose concentration. Regardless of the season, decreased body temperature was accompanied by a reduction in heart and breathing frequencies. Lower temperatures caused a significant decrease in arterial blood pressure during all four seasons. Hypoxia-induced changes in breathing frequency were proportional to body temperature and were more pronounced during winter, less so during spring and autumn and even smaller during summer. Season had no effect on the relationship between hypoxia and heart rate. At any temperature tested, the rate of oxygen consumption had a tendency to be highest during summer and lowest during winter, but the difference was significant only at 35 degrees C. The PaO2 and pH values showed no significant change during the year, but PaCO2 was almost twice as high during winter than in summer and spring, indicating increased plasma bicarbonate levels. Lower temperatures were accompanied by decreased plasma glucose levels, and this effect was greater during summer and smaller during autumn. Hypoxia-induced hyperglycaemia was influenced by temperature and season. During autumn and winter, plasma glucose level remained elevated regardless of temperature, probably to avoid dehydration and/or freezing. In winter, the bullfrog may be exposed not only to low temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since at low body temperatures the set-points of most physiological responses to hypoxia are reduced, regardless of the season.

The effect of water injection on nitric oxide emissions of a gas turbine combustor burning ASTM Jet-A fuel

NASA Technical Reports Server (NTRS)

Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

1973-01-01

Tests were conducted to determine the effect of water injection on oxides of nitrogen (NOx) emissions of a full annular, ram induction gas turbine combustor burning ASTM Jet-A fuel. The combustor was operated at conditions simulating sea-level takeoff and cruise conditions. Water at ambient temperature was injected into the combustor primary zone at water-fuel ratios up to 2. At an inlet-air temperature of 589 K (600 F) water injection decreased the NOx emission index at a constant exponential rate: NOx = NOx (o) e to the -15 W/F power (where W/F is the water-fuel ratio and NOx(o) indicates the value with no injection). The effect of increasing combustor inlet-air temperature was to decrease the effect of the water injection. Other operating variables such as pressure and reference Mach number did not appear to significantly affect the percent reduction in NOx. Smoke emissions were found to decrease with increasing water injection.

Modelling of nectarine drying under near infrared - Vacuum conditions.

PubMed

Alaei, Behnam; Chayjan, Reza Amiri

2015-01-01

Drying of nectarine slices was performed to determine the thermal and physical properties in order to reduce product deterioration due to chemical reactions, facilitate storage and lower transportation costs. Because nectarine slices are sensitive to heat with long drying period, the selection of a suitable drying approach is a challenging task. Infrared-vacuum drying can be used as an appropriate method for susceptible materials with high moisture content such as nectarine slices. Modelling of nectarine slices drying was carried out in a thin layer near infraredvacuum conditions. Drying of the samples was implemented at the absolute pressures of 20, 40 and 60 kPa and drying temperatures of 50, 60 and 70°C. Drying behaviour of nectarine slices, as well as the effect of drying conditions on moisture loss trend, drying rate, effective diffusion coefficient, activation energy, shrinkage, colour and energy consumption of nectarine slices, dried in near infrared-vacuum dryer are discussed in this study. Six mathematical models were used to predict the moisture ratio of the samples in thin layer drying. The Midilli model had supremacy in prediction of nectarine slices drying behaviour. The maximum drying rates of the samples were between 0.014-0.047 gwater/gdry material·min. Effective moisture diffusivity of the samples was estimated in the ranges of 2.46·10-10 to 6.48·10-10 m2/s. Activation energy were computed between 31.28 and 35.23 kJ/mol. Minimum shrinkage (48.4%) and total colour difference (15.1) were achieved at temperature of 50°C and absolute pressure of 20 kPa. Energy consumption of the tests was estimated in the ranges of 0.129 to 0.247 kWh. Effective moisture diffusivity was increased with decrease of vacuum pressure and increase of drying temperature but effect of drying temperature on effective moisture diffusivity of nectarine slices was more than vacuum pressure. Activation energy was decreased with decrease in absolute pressure. Total colour difference and shrinkage of nectarine slices on near infrared-vacuum drying was decreased with decrease of vacuum pressure and decrease of drying temperature.

Interactive effects of ocean acidification and warming on coral reef associated epilithic algal communities under past, present-day and future ocean conditions

NASA Astrophysics Data System (ADS)

Vogel, N.; Cantin, N. E.; Strahl, J.; Kaniewska, P.; Bay, L.; Wild, C.; Uthicke, S.

2016-06-01

Epilithic algal communities play critical ecological roles on coral reefs, but their response to individual and interactive effects of ocean warming (OW) and ocean acidification (OA) is still largely unknown. We investigated growth, photosynthesis and calcification of early epilithic algal community assemblages exposed for 6 months to four temperature profiles (-1.1, ±0.0, +0.9, +1.6 °C) that were crossed with four carbon dioxide partial pressure (pCO2) levels (360, 440, 650, 940 µatm), under flow-through conditions and natural light regimes. Additionally, we compared the cover of heavily calcified crustose coralline algae (CCA) and lightly calcified red algae of the genus Peyssonnelia among treatments. Increase in cover of epilithic communities showed optima under moderately elevated temperatures and present pCO2, while cover strongly decreased under high temperatures and high-pCO2 conditions, particularly due to decreasing cover of CCA. Similarly, community calcification rates were strongly decreased at high pCO2 under both measured temperatures. While final cover of CCA decreased under high temperature and pCO2 (additive negative effects), cover of Peyssonnelia spp. increased at high compared to annual average and moderately elevated temperatures. Thus, cover of Peyssonnelia spp. increased in treatment combinations with less CCA, which was supported by a significant negative correlation between organism groups. The different susceptibility to stressors most likely derived from a different calcification intensity and/or mineral. Notably, growth of the epilithic communities and final cover of CCA were strongly decreased under reduced-pCO2 conditions compared to the present. Thus, CCA may have acclimatized from past to present-day pCO2 conditions, and changes in carbonate chemistry, regardless in which direction, negatively affect them. However, if epilithic organisms cannot further acclimatize to OW and OA, the interacting effects of both factors may change epilithic communities in the future, thereby likely leading to reduced reef stability and recovery.

Effects of the bond polarity on the structural and dynamical properties of silica-like liquids

NASA Astrophysics Data System (ADS)

Pafong Sanjon, E.; Drossel, B.; Vogel, M.

2018-03-01

Silica is a network-forming liquid that shares many properties with water due to its tetrahedral structure. It undergoes a transition from a fragile to a strong liquid as the temperature is decreased, which is accompanied by a structural change to lower density and higher tetrahedral order. In order to disentangle the effects of Coulomb and van der Waals interactions on the structure and dynamics of liquid silica, we modify the bond polarity by changing the partial charges assigned to each atom. Using molecular dynamics simulations, we show that density, tetrahedral order, and structural relaxation times decrease when reducing bond polarity. Moreover, we find that the density maximum and the fragile-to-strong transition move to lower temperatures until they eventually vanish when the partial charges are decreased below approximately 75% of their regular value. Irrespective of whether strong or fragile behavior exists, structural relaxation is governed by hopping motion at sufficiently low temperatures. As long as there is a strong regime, the energy barrier associated with strong dynamics decreases with decreasing partial charges, but the dependence on the bond polarity differs from that of the activation energy in the Arrhenius regime at high temperatures. We show that the fragile-to-strong transition is associated with structural changes occurring between the first and second coordination shells that lead to a decrease in density and an increase in tetrahedral order. In particular, independent of the value of the partial charges, the distribution of the local structures is the same at this dynamic crossover, but we find no evidence that the effect occurs upon crossing the Widom line. In the fragile regime at intermediate temperatures, the relaxation times are well described by a previously proposed model which decomposes the apparent activation energy into a constant single-particle contribution and a temperature-dependent collective contribution. However, our results for silica-like melts do not obey several common relations of the model parameters reported for molecular glass formers.

Effects of Soil Temperature and Moisture on Soil Respiration on the Tibetan Plateau

PubMed Central

Chang, Xiaofeng; Wang, Shiping; Xu, Burenbayin; Luo, Caiyun; Zhang, Zhenhua; Wang, Qi; Rui, Yichao; Cui, Xiaoying

2016-01-01

Understanding of effects of soil temperature and soil moisture on soil respiration (Rs) under future warming is critical to reduce uncertainty in predictions of feedbacks to atmospheric CO2 concentrations from grassland soil carbon. Intact cores with roots taken from a full factorial, 5-year alpine meadow warming and grazing experiment in the field were incubated at three different temperatures (i.e. 5, 15 and 25°C) with two soil moistures (i.e. 30 and 60% water holding capacity (WHC)) in our study. Another experiment of glucose-induced respiration (GIR) with 4 h of incubation was conducted to determine substrate limitation. Our results showed that high temperature increased Rs and low soil moisture limited the response of Rs to temperature only at high incubation temperature (i.e. 25°C). Temperature sensitivity (Q10) did not significantly decrease over the incubation period, suggesting that substrate depletion did not limit Rs. Meanwhile, the carbon availability index (CAI) was higher at 5°C compared with 15 and 25°C incubation, but GIR increased with increasing temperature. Therefore, our findings suggest that warming-induced decrease in Rs in the field over time may result from a decrease in soil moisture rather than from soil substrate depletion, because warming increased root biomass in the alpine meadow. PMID:27798671

Increased Air Temperature during Simulated Autumn Conditions Impairs Photosynthetic Electron Transport between Photosystem II and Photosystem I1[OA

PubMed Central

Busch, Florian; Hüner, Norman P.A.; Ensminger, Ingo

2008-01-01

Changes in temperature and daylength trigger physiological and seasonal developmental processes that enable evergreen trees of the boreal forest to withstand severe winter conditions. Climate change is expected to increase the autumn air temperature in the northern latitudes, while the natural decreasing photoperiod remains unaffected. As shown previously, an increase in autumn air temperature inhibits CO2 assimilation, with a concomitant increased capacity for zeaxanthin-independent dissipation of energy exceeding the photochemical capacity in Pinus banksiana. In this study, we tested our previous model of antenna quenching and tested a limitation in intersystem electron transport in plants exposed to elevated autumn air temperatures. Using a factorial design, we dissected the effects of temperature and photoperiod on the function as well as the stoichiometry of the major components of the photosynthetic electron transport chain in P. banksiana. Natural summer conditions (16-h photoperiod/22°C) and late autumn conditions (8-h photoperiod/7°C) were compared with a treatment of autumn photoperiod with increased air temperature (SD/HT: 8-h photoperiod/22°C) and a treatment with summer photoperiod and autumn temperature (16-h photoperiod/7°C). Exposure to SD/HT resulted in an inhibition of the effective quantum yield associated with a decreased photosystem II/photosystem I stoichiometry coupled with decreased levels of Rubisco. Our data indicate that a greater capacity to keep the primary electron donor of photosystem I (P700) oxidized in plants exposed to SD/HT compared with the summer control may be attributed to a reduced rate of electron transport from the cytochrome b6f complex to photosystem I. Photoprotection under increased autumn air temperature conditions appears to be consistent with zeaxanthin-independent antenna quenching through light-harvesting complex II aggregation and a decreased efficiency in energy transfer from the antenna to the photosystem II core. We suggest that models that predict the effect of climate change on the productivity of boreal forests must take into account the interactive effects of photoperiod and elevated temperatures. PMID:18375598

Increased air temperature during simulated autumn conditions impairs photosynthetic electron transport between photosystem II and photosystem I.

PubMed

Busch, Florian; Hüner, Norman P A; Ensminger, Ingo

2008-05-01

Changes in temperature and daylength trigger physiological and seasonal developmental processes that enable evergreen trees of the boreal forest to withstand severe winter conditions. Climate change is expected to increase the autumn air temperature in the northern latitudes, while the natural decreasing photoperiod remains unaffected. As shown previously, an increase in autumn air temperature inhibits CO2 assimilation, with a concomitant increased capacity for zeaxanthin-independent dissipation of energy exceeding the photochemical capacity in Pinus banksiana. In this study, we tested our previous model of antenna quenching and tested a limitation in intersystem electron transport in plants exposed to elevated autumn air temperatures. Using a factorial design, we dissected the effects of temperature and photoperiod on the function as well as the stoichiometry of the major components of the photosynthetic electron transport chain in P. banksiana. Natural summer conditions (16-h photoperiod/22 degrees C) and late autumn conditions (8-h photoperiod/7 degrees C) were compared with a treatment of autumn photoperiod with increased air temperature (SD/HT: 8-h photoperiod/22 degrees C) and a treatment with summer photoperiod and autumn temperature (16-h photoperiod/7 degrees C). Exposure to SD/HT resulted in an inhibition of the effective quantum yield associated with a decreased photosystem II/photosystem I stoichiometry coupled with decreased levels of Rubisco. Our data indicate that a greater capacity to keep the primary electron donor of photosystem I (P700) oxidized in plants exposed to SD/HT compared with the summer control may be attributed to a reduced rate of electron transport from the cytochrome b6f complex to photosystem I. Photoprotection under increased autumn air temperature conditions appears to be consistent with zeaxanthin-independent antenna quenching through light-harvesting complex II aggregation and a decreased efficiency in energy transfer from the antenna to the photosystem II core. We suggest that models that predict the effect of climate change on the productivity of boreal forests must take into account the interactive effects of photoperiod and elevated temperatures.

Effects of temperature and pressure on thermodynamic properties of Cd0.50 Zn0.50 Se alloy

NASA Astrophysics Data System (ADS)

Aarifeen, Najm ul; Afaq, A.

2017-09-01

Thermodynamic properties of \\text{C}{{\\text{d}}0.50} \\text{Z}{{\\text{n}}0.50} Se alloy are studied using quasi harmonic model for pressure range 0-10 GPa and temperature range 0-1000 K. The structural optimization is obtained by self consistent field calculations and full-potential linear muffin-tin orbital method with GGA+U as an exchange correlation functional where U=2.3427 eV is the hubbard potential. The effects of temperature and pressure on the bulk modulus, Helmholtz free energy, internal energy, entropy, Debye temperature, Grüneisen parameter, thermal expansion coefficient and heat capacities of the material are observed and discussed. The bulk modulus, Helmholtz free energy and Debye temperature are found to decrease with increasing temperature while there is an increasing behavior when the pressure rises. Whereas internal energy has increasing trend with rises in temperature and it almost remains insensitive to pressure. The entropy of the system increases (decreases) with a rise of pressure (temperature).

The effect of temperature on cell growth and astaxanthin accumulation of Haematococcus pluvialis during a light-dark cyclic cultivation.

PubMed

Wan, Minxi; Zhang, Jingkui; Hou, Dongmei; Fan, Jianhua; Li, Yuanguang; Huang, Jianke; Wang, Jun

2014-09-01

Haematococcus pluvialis is the best source of natural astaxanthin known as "the king of antioxidants". The mass outdoor culture is the most workable strategy for astaxanthin production, but the effects of daytime and night temperatures on the biomass concentration and astaxanthin content of H. pluvialis have received little attention. This study indicated that, raising the daytime or night temperature could stimulate night accumulation of astaxanthin until temperature up to 28°C; the night biomass loss increased firstly and then decreased along with the daytime temperature reducing; decreasing the night temperature can lessen night biomass loss; the daytime temperature of 28°C and the night temperature below 28°C were optimal for achieving high biomass and astaxanthin content. Subsequently, the outdoor culture strategy has been improved and can increase the net biomass and astaxanthin productivities by 5 and 2.9-fold as compared to the former strategy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Milk pH as a function of CO2 concentration, temperature, and pressure in a heat exchanger.

PubMed

Ma, Y; Barbano, D M

2003-12-01

Raw skim milk, with or without added CO2, was heated, held, and cooled in a small pilot-scale tubular heat exchanger (372 ml/min). The experiment was replicated twice, and, for each replication, milk was first carbonated at 0 to 1 degree C to contain 0 (control), 600, 1200, 1800, and 2400 ppm added CO2 using a continuous carbonation unit. After storage at 0 to 1 degree C, portions of milk at each CO2 concentration were heated to 40, 56, 72, and 80 degrees C, held at the desired temperature for 30 s (except 80 degrees C, holding 20 s) and cooled to 0 to 1 degree C. At each temperature, five pressures were applied: 69, 138, 207, 276, and 345 kPa. Pressure was controlled with a needle valve at the heat exchanger exit. Both the pressure gauge and pH probe were inline at the end of the holding section. Milk pH during heating depended on CO2 concentration, temperature, and pressure. During heating of milk without added CO2, pH decreased linearly as a function of increasing temperature but was independent of pressure. In general, the pH of milk with added CO2 decreased with increasing CO2 concentration and pressure. For milk with added CO2, at a fixed CO2 concentration, the effect of pressure on pH decrease was greater at a higher temperature. At a fixed temperature, the effect of pressure on pH decrease was greater for milk with a higher CO2 concentration. Thermal death of bacteria during pasteurization of milk without added CO2 is probably due not only to temperature but also to the decrease in pH that occurs during the process. Increasing milk CO2 concentration and pressure decreases the milk pH even further during heating and may further enhance the microbial killing power of pasteurization.

Reduction effect of surface temperature of baked bricks with different pore shapes during absorption-evaporation test

NASA Astrophysics Data System (ADS)

Oguchi, Chiaki T.; Shinozuka, Katsumi

2017-04-01

To study the effect of decreasing in surface temperature of baked bricks with various pore shapes, the present study performed several experiments such as water absorbance test and heating test. For the preparation of experimental specimens, bricks with artificial spherical pores, artificial linear pores and non-additional artificial pores were made. The bricks were examined their properties of bulk density, Equotip hardness and absorbing properties by putting in the water. Wet bricks were also put in the incubator set at 50 °C, and monitored the increasing of surface temperature of each brick. Brick with linear pores shows higher water absorption rate in a short time than those with spherical pores. They evaporated moisture faster than those with a spherical pores. They kept the temperature by 11.7 °C lower than the setting temperature, whereas the bricks with a spherical pores kept the temperature by 10.5 °C . Bricks with linear pores has about 10% higher effectiveness of decreasing in surface temperature than those with spheroidal pores.

Small angle neutron scattering analyses and high temperature mechanical properties of nano-structured oxide dispersion strengthened steels produced via cryomilling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jeoung Han; Byun, Thak Sang; Shin, Eunjoo

2015-08-17

Three oxide dispersion-strengthened (ODS) steels are produced in order to investigate the effect of the mechanical alloying (MA) temperature on the microstructural evolution and high temperature mechanical properties. The microstructural evolution with different MA conditions is examined using small angle neutron scattering. As the MA temperature decreases, the density of the nanoclusters below 10 nm increases and their mean diameter decreases. A low temperature during MA leads to a high strength in the compression tests performed at 500 *C; however, this effect disappears in testing at 900 *C. The milling process at *70 *C exhibits excellent high fracture toughness, whichmore » is better than the benchmark material 14YWT-SM10. However, the *150 *C milling process results in significantly worse fracture toughness properties. The reasons for this strong temperature dependency are discussed.« less

Interaction Between Neuronal NOS Signaling and Temperature Influences SR Ca2+ Leak:Role of Nitroso-Redox Balance

PubMed Central

Dulce, Raul A.; Mayo, Vera; Rangel, Erika B.; Balkan, Wayne; Hare, Joshua M.

2014-01-01

Rationale While nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results due to inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here we show that temperature significantly modulates NO effects. Objective Test the hypothesis that temperature profoundly impacts nitroso-redox equilibrium, thereby affecting sarcomeric reticulum (SR) Ca2+ leak. Methods and Results We measured SR Ca2+ leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (NOS1−/−), and hyper S-nitrosylation (GSNOR−/−) mice. In WT cardiomyocytes, SR Ca2+ leak increased as temperature decreased from 37°C to 23°C, whereas, in NOS1−/ −cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR−/ − cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1−/− cardiomyocytes; reducing leak at 37°C but increasing it at sub-physiologic temperatures. Oxypurinol and Tempol diminished the leak in NOS1−/ − cardiomyocytes. Cooling from 37° to 23°C increased ROS generation in WT but decreased it in NOS1−/− cardiomyocytes. Oxypurinol further reduced ROS generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca2+ content in NOS1−/− cells but had no effect in WT or GSNOR−/−. Conclusions Ca2+ leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating ROS production as temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and ROS which in turn has a major impact on SR Ca2+. PMID:25326127

Effect of annealing on structural, optical and electrical properties of SILAR synthesized CuO thin film

NASA Astrophysics Data System (ADS)

Das, M. R.; Mukherjee, A.; Mitra, P.

2017-05-01

Nano crystalline CuO thin films were synthesize on glass substrate using SILAR technique. The structural, optical and electrical properties of the films were carried out for as deposited as well as for films post annealed in the temperature range 300 - 500° C. The X-ray diffraction pattern shows all the films are polycrystalline in nature with monoclinic phase. The crystallite size increase and lattice strain decreases with increase of annealing temperature indicating high quality of the films for annealed films. The value of band gap decreases with increases of annealing temperature of the film. The effect of annealing temperature on ionic conductivity and activation energy to electrical conduction process are discussed.

Effects of open-air temperature on air temperature inside biological safety cabinet.

PubMed

Umemura, Masayuki; Shigeno, Katsuro; Yamamura, Keiko; Osada, Takashi; Soda, Midori; Yamada, Kiyofumi; Ando, Yuichi; Wakiya, Yoshifumi

2011-02-14

In Japan, biological safety cabinets (BSCs) are normally used by medical staff while handling antineoplastic agents. We have also set up a class II B2 BSC at the Division of Chemotherapy for Outpatients. The air temperature inside this BSC, however, decreases in winter. We assumed that this decrease is caused by the intake of open-air. Therefore, we investigated the effects of low open-air temperature on the BSC temperature and the time of admixtures of antineoplastic agents. The studies were conducted from January 1 to March 31, 2008. The outdoor air temperature was measured in the shade near the intake nozzle of the BSC and was compared with the BSC temperature. The correlation between the outdoor air temperature and the BSC temperature, the dissolution time of cyclophosphamide (CPA) and gemcitabine (GEM), and accurate weight measurement of epirubicin (EPI) solution were investigated for low and normal BSC temperatures. The BSC temperature was correlated with the open-air temperature for open-air temperatures of 5-20°C (p < 0.0001). The dissolution of CPA and GEM at these temperatures was significantly delayed as compared to that at 25°C (p < 0.01 and p < 0.0001, respectively). The weight measurement of EPI solution using a syringe method lacks accuracy because of its high coefficient of viscosity at low temperatures (p < 0.01). These results suggest that the BSC temperature decreases below room temperature in winter when air is drawn from outdoors. We showed that the BSC temperature affects the dissolution rate of antineoplastic agents. Further, we suggested that the BSC temperature drop might delay the affair of the admixtures of antineoplastic agents and increase the waiting time of outpatients for chemotherapy.

Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study

PubMed Central

Meng, Xiankai; Zhou, Jianzhong; Huang, Shu; Su, Chun; Sheng, Jie

2017-01-01

The laser shock wave (LSW) generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations. PMID:28772433

Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study.

PubMed

Meng, Xiankai; Zhou, Jianzhong; Huang, Shu; Su, Chun; Sheng, Jie

2017-01-18

The laser shock wave (LSW) generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations.

Fishing and bottom water temperature as drivers of change in maximum shell length in Atlantic surfclams (Spisula solidissima)

NASA Astrophysics Data System (ADS)

Munroe, D. M.; Narváez, D. A.; Hennen, D.; Jacobson, L.; Mann, R.; Hofmann, E. E.; Powell, E. N.; Klinck, J. M.

2016-03-01

Maximum shell length of Atlantic surfclams (Spisula solidissima) on the Middle Atlantic Bight (MAB) continental shelf, obtained from federal fishery survey data from 1982-present, has decreased by 15-20 mm. Two potential causes of this decreasing trend, fishery removal of large animals and stress due to warming bottom temperatures, were investigated using an individual-based model for post-settlement surfclams and a fifty-year hindcast of bottom water temperatures on the MAB. Simulations showed that fishing and/or warming bottom water temperature can cause decreases in maximum surfclam shell length (body size) equivalent to those observed in the fished stock. Independently, either localized fishing rates of 20% or sustained bottom temperatures that are 2 °C warmer than average conditions generate the observed decrease in maximum shell length. However, these independent conditions represent extremes and are not sustained in the MAB. The combined effects of fishing and warmer temperatures can generate simulated length decreases that are similar to observed decreases. Interannual variability in bottom water temperatures can also generate fluctuations in simulated shell length of up to 20 mm over a period of 10-15 years. If the change in maximum size is not genotypic, simulations also suggest that shell size composition of surfclam populations can recover if conditions change; however, that recovery could take a decade to become evident.

Low temperature stress on the hematological parameters and HSP gene expression in the turbot Scophthalmus maximus

NASA Astrophysics Data System (ADS)

Ji, Liqin; Jiang, Keyong; Liu, Mei; Wang, Baojie; Han, Longjiang; Zhang, Mingming; Wang, Lei

2016-05-01

To study the effect of low temperature stress on hematological parameters and HSP gene expression in the turbot ( Scophthalmus maximus), water temperature was lowered rapidly from 18 to 1°C. During the cooling process, three individuals were removed from culture tanks at 18, 13, 8, 5, 3, and 1°C. Blood samples and tissues were taken from each individual, hematological indices and HSP gene expression in tissues were measured. The red blood cell count, white blood cell count, and hemoglobin concentration decreased significantly ( P < 0.05) as temperature decreased. Enzyme activities of plasma alanine transaminase and creatine kinase increased as temperature decreased, whereas aspartic transaminase and γ-glutamyl transpeptidase activities displayed no obvious changes above 1°C and lactate dehydrogenase activity increased first and then decreased. Blood urea nitrogen and uric acid levels were highest at 8°C, and creatinine concentration was highest at 3°C. The concentrations of plasma cortisol, cholesterol, and triglyceride all increased significantly ( P < 0.05) as temperature decreased. The serum glucose concentration increased first and then decreased to the initial level. The HSP70 mRNA expression showed various patterns in different tissues, whereas HSP90 mRNA expression showed the same tendency in all tissues. Overall, these results indicate that temperature decreases in the range of 8 to 5°C may induce a stress response in S. maximus and that temperature should be kept above 8°C in the aquaculture setting to avoid damage to the fish.

The effect of mass loading on the temperature of a flowing plasma. [in vicinity of Io

NASA Technical Reports Server (NTRS)

Linker, Jon A.; Kivelson, Margaret G.; Walker, Raymond J.

1989-01-01

How the addition of ions at rest (mass loading) affects the temperature of a flowing plasma in a MHD approximation is investigated, using analytic theory and time dependent, three-dimensional MHD simulations of plasma flow past Io. The MHD equations show that the temperature can increase or decrease relative to the background, depending on the local sonic Mach number M(S), of the flow. For flows with M(S) of greater than sq rt 9/5 (when gamma = 5/3), mass loading increases the plasma temperature. However, the simulations show a nonlinear response to the addition of mass. If the mass loading rate is large enough, the temperature increase may be smaller than expected, or the temperature may actually decrease, because a large mass loading rate slows the flow and decreases the thermal energy of the newly created plasma.

Temperature effects on stocks and stability of a phytoplankton-zooplankton model and the dependence on light and nutrients

USGS Publications Warehouse

Norberg, J.; DeAngelis, D.L.

1997-01-01

A model of a closed phytoplankton—zooplankton ecosystem was analyzed for effects of temperature on stocks and stability and the dependence of these effects on light and total nutrient concentration of the system. An analysis of the steady state equations showed that the effect of temperature on zooplankton and POM biomass was levelled when primary production is nutrient limited. Temperature increase had a generally negative effect on all biomasses at high nutrient levels due to increased maintenance costs. Nutrient limitation of net primary production is the main factor governing the effect of stocks and flows as well as the stability of the system. All components of the system, except for phytoplankton biomass, are proportional to net production and thus to the net effect of light on photosynthesis. However, temperature determines the slope of that relationship. The resilience of the system was measured by calculating the eigenvalues of the steady state. Under oligotrophic conditions, the system can be stable, but an increase in temperature can cause instability or a decrease in resilience. This conclusion is discussed in the face of recent models that take spatial heterogeneity into account and display far more stable behavior, in better agreement to empirical data. Using simulations, we found that the amplitude of fluctuations of the herbivore stock increases with temperature while the mean biomass and minimum values decrease in comparison with steady state predictions

Effects of chronic exposure to cadmium and temperature, alone or combined, on the threespine stickleback (Gasterosteus aculeatus): Interest of digestive enzymes as biomarkers.

PubMed

Hani, Younes Mohamed Ismail; Turies, Cyril; Palluel, Olivier; Delahaut, Laurence; Gaillet, Véronique; Bado-Nilles, Anne; Porcher, Jean-Marc; Geffard, Alain; Dedourge-Geffard, Odile

2018-06-01

The development of predictive, sensitive and reliable biomarkers is of crucial importance for aquatic biomonitoring to assess the effects of chemical substances on aquatic organisms, especially when it comes to combined effects with other stressors (e.g. temperature). The first purpose of the present study was to evaluate the single and combined effects of 90 days of exposure to an environmental cadmium concentration (0.5 μg L -1 ) and two water temperatures (16 and 21 °C) on different parameters. These parameters are involved in (i) the antioxidant system (superoxide dismutase activity -SOD- and total glutathione levels -GSH-), (ii) the energy metabolism, i.e. energy reserves (glycogen, lipids, proteins) and digestive enzymes (trypsin, amylase, intestinal alkaline phosphatase -IAP-), and (iii) biometric parameters (weight, length, Fulton's condition factor, and the gonadosomatic index -GSI-) of threespine stickleback (Gasterosteus aculeatus). The second purpose was to determine the interest of the three digestive enzymes as biomarkers in comparison with the other parameters. The higher temperature (21 °C) impacted the anti-oxidant and energy reserve parameters. In liver, GSH levels increased on day 60, while SOD decreased on days 15 and 90, with a significant decrease of protein and lipid energy reserves on day 90. In muscle, the higher temperature decreased SOD activity only on day 90. G. aculeatus biometric parameters were also impacted by the higher temperature, which limited stickleback growth after 90 days of exposure. In female sticklebacks, the GSI peaked on day 60 and decreased sharply on day 90, while the highest values were reached at day 90 in the control groups, suggesting impaired reproduction in sticklebacks raised at 21 °C. These results suggest that 21 °C is an upper-limit temperature for long-term physiological processes in sticklebacks. In contrast, very low-concentration cadmium exposure had no effect on classical biomarkers (energy reserves, antioxidant parameters, biometric parameters). However, digestive enzymes showed an interesting sensitivity to cadmium, which was emphasized by high temperature. The activity of the three digestive enzymes decreased significantly on day 90 when sticklebacks were exposed to cadmium alone, while the decrease was stronger and was recorded earlier (from day 15) when they were exposed to the cadmium-temperature combination. Compared to conventional measurements, digestive enzymes responded rapidly. This could be an important advantage for them to be used as early warning tools to reflect the health status of organisms, particularly for trypsin and IAP activities. Copyright © 2018 Elsevier B.V. All rights reserved.

Study of Ti 4+ substitution in ZrW 2O 8 negative thermal expansion materials

NASA Astrophysics Data System (ADS)

De Buysser, Klaartje; Van Driessche, Isabel; Putte, Bart Vande; Schaubroeck, Joseph; Hoste, Serge

2007-08-01

Powder XRD-analysis and thermo-mechanical analysis on sintered TiO 2-WO 3-ZrO 2 mixtures revealed the formation of Zr 1-xTi xW 2O 8 solid solutions. A noticeable decrease in unit cell parameter ' a' and in the order-disorder transition temperature could be seen in the case of Zr 1-xTi xW 2O 8 solid solutions. Studies performed on other ZrW 2O 8 solid solutions have attributed an increase in phase transition temperature to a decrease in free lattice volume, whereas a decrease in phase transition temperature was suggested to be due to the presence of a more disordered state. Our studies indicate that the phase transition temperature in our materials is strongly influenced by the bond dissociation energy of the substituting ion-oxygen bond. A decrease in bond strength may compensate for the effect of a decrease in lattice free volume, lowering the phase transition temperature as the degree of substitution by Ti 4+ increases. This hypothesis is proved by differential scanning calorimetry.

Dissolution and aggregation of Cu nanoparticles in culture media: effects of incubation temperature and particles size

NASA Astrophysics Data System (ADS)

Li, Lingxiangyu; Fernández-Cruz, María Luisa; Connolly, Mona; Schuster, Michael; Navas, José María

2015-01-01

Here, the effects of incubation temperature and particle size on the dissolution and aggregation behavior of copper nanoparticles (CuNPs) in culture media were investigated over 96 h, equivalent to the time period for acute cell toxicity tests. Three CuNPs with the nominal sizes of 25, 50, and 100 nm and one type of micro-sized particles (MPs, 500 nm) were examined in culture media used for human and fish hepatoma cell lines acute tests. A large decrease in sizes of CuNPs in the culture media was observed in the first 24 h incubation, and subsequently the sizes of CuNPs changed slightly over the following 72 h. Moreover, the decreasing rate in size was significantly dependent on the incubation temperature; the higher the incubation temperature, the larger the decreasing rate in size. In addition to that, we also found that the release of copper ions depended on the incubation temperature. Moreover, the dissolution rate of Cu particles increased very fast in the first 24 h, with a slight increase over the following 72 h.

Effect of pyrolysis temperature on the chemical oxidation stability of bamboo biochar.

PubMed

Chen, Dengyu; Yu, Xinzhi; Song, Chao; Pang, Xiaoli; Huang, Jing; Li, Yanjun

2016-10-01

Biochar produced by biomass pyrolysis has the advantage of carbon sequestration. However, some of the carbon atoms in biochar are not very stable. In this study, the effect of pyrolysis temperature on the chemical oxidation stability of bamboo biochar was investigated using the atomic ratios of H/C and O/C, Fourier transform infrared spectroscopy, and potassium dichromate (K2Cr2O7) oxidation spectrophotometric method. The results show that the carbon yield and ratios of H/C and O/C decreased from 71.72%, 0.71, and 0.32 to 38.48%, 0.22, and 0.06, respectively, as the temperature was increased from 300°C to 700°C. Moreover, the main oxygen-containing functional groups gradually decreased, while the degree of aromatization increased accordingly. The biochar showed a better stability at a higher pyrolysis temperature. The proportion of carbon loss, i.e., the amount of oxidized carbon with respect to the total carbon of the biochar, decreased from 16.52% to 6.69% with increasing temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Defect-induced change of temperature-dependent elastic constants in BCC iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, N.; Setyawan, W.; Zhang, S. H.

2017-07-01

The effects of radiation-induced defects (randomly distributed vacancies, voids, and interstitial dislocation loops) on temperature-dependent elastic constants, C11, C12, and C44 in BCC iron, are studied with molecular dynamics method. The elastic constants are found to decrease with increasing temperatures for all cases containing different defects. The presence of vacancies, voids, or interstitial loops further decreases the elastic constants. For a given number of point defects, the randomly distributed vacancies show the strongest effect compared to voids or interstitial loops. All these results are expected to provide useful information to combine with experimental results for further understanding of radiation damage.

The effect of spray-drying parameters on the flavor of nonfat dry milk and milk protein concentrate 70.

PubMed

Park, Curtis W; Stout, Mark A; Drake, MaryAnne

2016-12-01

Unit operations during production influence the sensory properties of nonfat dry milk (NFDM) and milk protein concentrate (MPC). Off-flavors in dried dairy ingredients decrease consumer acceptance of ingredient applications. Previous work has shown that spray-drying parameters affect physical and sensory properties of whole milk powder and whey protein concentrate. The objective of this study was to determine the effect of inlet temperature and feed solids concentration on the flavor of NFDM and MPC 70% (MPC70). Condensed skim milk (50% solids) and condensed liquid MPC70 (32% solids) were produced using pilot-scale dairy processing equipment. The condensed products were then spray dried at either 160, 210, or 260°C inlet temperature and 30, 40, or 50% total solids for NFDM and 12, 22, or 32% for MPC70 in a randomized order. The entire experiment was replicated 3 times. Flavor of the NFDM and MPC70 was evaluated by sensory and instrumental volatile compound analyses. Surface free fat, particle size, and furosine were also analyzed. Both main effects (30, 40, and 50% solids and 160, 210, and 260°C inlet temperature) and interactions between solids concentration and inlet temperature were investigated. Interactions were not significant. In general, results were consistent for NFDM and MPC70. Increasing inlet temperature and feed solids concentration increased sweet aromatic flavor and decreased cardboard flavor and associated lipid oxidation products. Increases in furosine with increased inlet temperature and solids concentration indicated increased Maillard reactions during drying. Particle size increased and surface free fat decreased with increasing inlet temperature and solids concentration. These results demonstrate that increasing inlet temperatures and solids concentration during spray drying decrease off-flavor intensities in NFDM and MPC70 even though the heat treatment is greater compared with low temperature and low solids. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Vertical profiles reveal impact of ozone and temperature on carbon assimilation of Betula pendula and Populus tremula.

PubMed

Mäenpää, Maarit; Riikonen, Johanna; Kontunen-Soppela, Sari; Rousi, Matti; Oksanen, Elina

2011-08-01

Rising temperature and tropospheric ozone (O(3)) concentrations are likely to affect carbon assimilation processes and thus the carbon sink strength of trees. In this study, we investigated the joint action of elevated ozone and temperature on silver birch (Betula pendula) and European aspen (Populus tremula) saplings in field conditions by combining free-air ozone exposure (1.2 × ambient) and infrared heaters (ambient +1.2 °C). At leaf level measurements, elevated ozone decreased leaf net photosynthesis (P(n)), while the response to elevated temperature was dependent on leaf position within the foliage. This indicates that leaf position has to be taken into account when leaf level data are collected and applied. The ozone effect on P(n) was partly compensated for at elevated temperature, showing an interactive effect of the treatments. In addition, the ratio of photosynthesis to stomatal conductance (P(n)/g(s) ratio) was decreased by ozone, which suggests decreasing water use efficiency. At the plant level, the increasing leaf area at elevated temperature resulted in a considerable increase in photosynthesis and growth in both species.

Developmental Effects of Ocean Acidification Conditions and Elevated Temperature on Homarus Americanus Larvae

NASA Astrophysics Data System (ADS)

Mcveigh, H.; Waller, J. D.

2016-02-01

The Gulf of Maine is experiencing a rapid warming in sea surface temperature and a marked decrease in pH. This study aimed to quantify the impact of elevated temperature and acidification on the larval development of the iconic American lobster (Homarus americanus). Experimental conditions were reflective of current and IPCC predicted levels of temperature and pCO2 to be reached by the end of the century. Larvae were measured for growth (carapace length), development time, and survivorship over the larval duration. Treatments of elevated temperatures experienced decreased development time across the larval stages of H. americanus. Consequently mortality increased at a significantly higher rate under elevated temperature. An increase in larval mortality may decrease recruitment to the commercial fishery, thus impacting the most valuable single species in the state of Maine. Furthermore, experimental pCO2 treatments yielded a significantly decreased development time between larval stages II and III, yet did not have a significant impact on carapace length or mortality. This study indicates that warmer temperatures may have a greater influence than decreased pH on larval development and survival. Determining how this species may respond to changing climactic conditions will better inform the sustainability efforts of such a critical marine fishery.

A moderate decrease in temperature induces COR15a expression through the CBF signaling cascade and enhances freezing tolerance.

PubMed

Wang, Yi; Hua, Jian

2009-10-01

Temperature has a profound effect on plant growth and development. However, the molecular mechanisms underlying this regulation are not well understood. In particular, how moderate temperature variations are perceived and transduced inside the plant cells remains obscure. In this study, we analyzed transcriptional responses to a moderate decrease in temperature (cooling) in Arabidopsis thaliana. The cooling response involves a weaker and more transient induction of cold-induced genes, such as COR15a, than cold response. This induction probably accounts for the increase in freezing tolerance by cooling acclimation. Cooling also induces some defense response genes, and their induction, but not that of COR15a, requires the salicylic acid signaling pathway. Analysis of the regulation of COR15a reveals that cooling induction is mediated through the same C repeat/dehydration-responsive (CRT/DRE) element as cold induction. Furthermore, we identified a role for CBF1 and CBF4 in transducing signals of moderate decreases in temperature. It appears that variants of the CBF signaling cascade are utilized in cold and cooling responses, and a moderate decrease in temperature may invoke an adaptive response to prepare plants to cope with a more drastic decrease in temperature.

Effects of Environmental Temperature and Dietary Fat Content on The Performance and Heat Production and Substrate Oxidation in Growing Pigs.

PubMed

Han, Rui; Jiang, Hailong; Che, Dongsheng; Bao, Nan; Xiang, Dong; Liu, Feifei; Yang, Huaming; Ban, Zhibin; Qin, Guixin

2017-01-01

This study aimed to evaluate the effect of temperature and dietary fat level on growth performance, heat production, nutrient oxidation and nitrogen balance in growing pigs. Thirty-two pigs (Duroc × Landrace × Large White) with initial weight of 25±1.91 kg were assigned to treatments in 2×4 factorial design. All pigs were fed with two isoenergetic and isoproteic diets of different fat levels (low fat level: 3.68% fat of dry matter (DM) and high fat level: 8.39% fat of DM) under four environmental temperatures (23, 18, 13 and 8 ºC). Heat production (HP) and nutrient oxidation were calculated from gas exchange via measurement with respiration chambers. The results showed that there was no interaction effect on growth performance by the temperature and dietary fat level. The average daily feed intake (ADFI) was lower (P < 0.001), the average daily gain (ADG) was higher (P < 0.001) and feed utilization was more efficient at 23 ºC than 13 and 8 ºC (P < 0.001). Dietary fat had no effect on growth performance and feed utilization at the four different temperatures. A significant interaction (P < 0.001) between temperature and dietary fat level on oxidation of carbohydrate (OXCHO) and fat (OXF) was observed. HP, OXF and OXCHO were significantly increased (P < 0.001) as environment temperatures decreased. Increasing dietary fat generated an increase in the OXF and decrease in the OXCHO (P < 0.001). No significant difference was observed in protein oxidation (OXP) of two factors. The intakes of nitrogen, nitrogen excretion in feces (FN) and urine (UN) by the pigs kept in 8 ºC environment were highest. Nitrogen digestibility decreased as environmental temperature decreased, with the most efficient gains obtained at 23 ºC. However, nitrogen retention was not influenced by environmental temperature. Dietary fat level did not affect nitrogen balance. No significant interaction between temperature and dietary fat level was observed for nitrogen balance. These results indicated that the rate of growth and nutrition utilization in pigs fed ad libitum are influenced by the environmental temperatures in which they are maintained, and the oxidation of nutrition utilization of the pig to different environmental temperatures is altered by the dietary fat supplementation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Effects of increased levels of atmospheric CO2 and high temperatures on rice growth and quality

PubMed Central

Waqas, Muhammad Ahmed; Wang, Song-he; Xiong, Xiang-yang; Wan, Yun-fan

2017-01-01

The increased atmospheric temperatures resulting from the increased concentration of atmospheric carbon dioxide (CO2) have had a profound influence on global rice production. China serves as an important area for producing and consuming rice. Therefore, exploring the effects of the simultaneously rising levels of atmospheric CO2 and temperatures on rice growth and quality in the future is very important. The present study was designed to measure the most important aspects of variation for rice-related physiological, ecological and quality indices in different growing periods under a simultaneous increase of CO2 and temperature, through simulation experiments in climate-controlled growth chambers, with southern rice as the study object. The results indicated that the ecological indices, rice phenology, and leaf area would decrease under a simultaneous increase of CO2 and temperature. For the physiological indices, Malondialdehyde (MDA) levels increased significantly in the seedling period. However, it showed the trend of increase and subsequent decrease in the heading and filling periods. In addition, the decomposition of soluble protein (SP) and soluble sugar (SS) accelerated in filling period. The rice quality index of the Head Rice Rate showed the decreasing trend and subsequent increase, but the Chalky Rice Rate and Protein Content indices gradually decreased while the Gel Consistency gradually increased. PMID:29145420

The effect of ephedrine on intraoperative hypothermia

PubMed Central

Jo, Youn Yi; Kim, Ji Young; Kim, Joon-Sik; Kwon, Youngjun

2011-01-01

Background Prevention of intraoperative hypothermia has become a standard of operative care. Since ephedrine has a thermogenic effect and it is frequently used to treat hypotension during anesthesia, this study was designed to determine the effect of ephedrine on intraoperative hypothermia of patients who are undergoing spine surgery. Methods Twenty-four patients were randomly divided to receive an ephedrine (the ephedrine group, n = 12) or normal saline (the control group, n = 12) infusion for 2 h. The esophageal temperature (the core temperature), the index finger temperature (the peripheral temperature) and the hemodynamic variables such as the mean blood pressure and heart rate were measured every 15 minutes after the intubation. Results At the end of the study period, the esophageal temperature and hemodynamic variables were significantly decreased in the control group, whereas those in the ephedrine group were stably maintained. The index finger temperature was significantly lower in the ephedrine group compared to that in the control group, suggesting the prevention of core-to-peripheral redistribution of the heat as the cause of temperature maintenance. Conclusions An intraoperative infusion of ephedrine minimized the decrease of the core temperature and it stably maintained the hemodynamic variables during spine surgery with the patient under general anesthesia. PMID:21602974

Effectiveness of Different Urban Heat Island Mitigation Methods and Their Regional Impacts

NASA Astrophysics Data System (ADS)

Zhang, N.

2017-12-01

Cool roofs and green roofs are two popular methods to mitigate urban heat island and improve urban climate. The effectiveness of different urban heat island mitigation strategies in the summer of 2013 in the Yangtze River Delta, China is investigated using the WRF (Weather Research and Forecasting) model coupled with a physically based urban canopy model. The modifications to the roof surface changed the urban surface radiation balance and then modified the local surface energy budget. Both cool roofs and green roofs led to lower surface skin temperature and near-surface air temperature. Increasing the roof albedo to 0.5 caused a similar effectiveness as covering 25% of urban roofs with vegetation; increasing roof albedo to 0.7 caused a similar near-surface air temperature decrease as 75% green roof coverage. The near-surface relative humidity increased in both cool roof and green roof experiments because of the combination of the impacts of increases in specific humidity and decreases in air temperature. The regional impacts of cool roofs and green roofs were evaluated using the regional effect index. The regional effect could be found in both near-surface air temperature and surface specific/relative humidity when the percentage of roofs covered with high albedo materials or green roofs reached a higher fraction (greater than 50%). The changes in the vertical profiles of temperature cause a more stable atmospheric boundary layer over the urban area; at the same time, the crossover phenomena occurred above the boundary layer due to the decrease in vertical wind speed.

Temperature dependence of O2 consumption; opposite effects of leptin and etomoxir on respiratory quotient in mice.

PubMed

Högberg, Helena; Engblom, Lars; Ekdahl, Asa; Lidell, Veronica; Walum, Erik; Alberts, Peteris

2006-04-01

The aims were to compare the temperature dependence of the metabolic rate in young ob/ob mice with that in mature ob/ob and db/db mice and to examine the effect on the metabolic substrate preference of leptin and etomoxir in ob/ob, C57BL/6J (wild-type), and db/db mice. In vivo oxygen consumption and carbon dioxide production were continuously measured by indirect calorimetry, and body temperature and total locomotor activity were measured by an implanted transponder. Leptin, etomoxir, or vehicle was administered intraperitoneally. The temperature dependence of the metabolic rate of mature ob/ob and db/db mice were similar to that in wild-type mice. In young 6-week-old ob/ob mice, the metabolic rate was almost doubled at 15 degrees C. Leptin (2 x 3 mg/kg) decreased the respiratory quotient (RQ) and carbon dioxide production but did not alter oxygen consumption, body temperature, or locomotor activity in ob/ob and C57BL/6J mice and had no effect in the db/db mice. Etomoxir (2 x 30 mg/kg) enhanced RQ and decreased oxygen consumption, carbon dioxide production, and body temperature in ob/ob, C57BL/6J, and db/db mice. Total locomotor activity was reduced in ob/ob and C57BL/6J mice. In young ob/ob mice, the temperature sensitivity was enhanced compared with mature mice. Leptin and etomoxir had opposite effects on metabolic substrate preference. Leptin and lowered environmental temperature increased the relative fat oxidation as indicated by decreased RQ, possibly through activation of the sympathetic nervous system.

Riparian forest as a management tool for moderating future thermal conditions of lowland temperate streams

NASA Astrophysics Data System (ADS)

Kristensen, P. B.; Kristensen, E. A.; Riis, T.; Baisner, A. J.; Larsen, S. E.; Verdonschot, P. F. M.; Baattrup-Pedersen, A.

2013-05-01

Predictions of the future climate infer that stream water temperatures may increase in temperate lowland areas and that streams without riparian forest will be particularly prone to elevated stream water temperature. Planting of riparian forest is a potential mitigation measure to reduce water temperatures for the benefit of stream organisms. However, no studies have yet determined the length of a forested reach required to obtain a significant temperature decrease. To investigate this we measured the temperature in five small Danish lowland streams from June 2010 to July 2011, all showing a sharp transition between an upstream open reach and a downstream forested reach. In all stream reaches we also measured canopy cover and a range of physical variables characterizing the streams reaches. This allowed us to analyse differences in mean daily temperature and amplitude per month among forested and open sections as well as to study annual temperature regimes and the influence of physical conditions on temperature changes. Stream water temperature in the open reaches was affected by heating, and in July we observed an increase in temperature over the entire length of the investigated reaches, reaching temperatures higher than the incipient lethal limit for brown trout. Along the forest reaches a significant decrease in July temperatures was recorded immediately (100 m) when the stream moved into the forested area. In three of our study streams the temperature continued to decrease the longer the stream entered into the forested reach, and the temperature decline did not reach a plateau. The temperature increases along the open reaches were accompanied by stronger daily temperature variation; however, when the streams entered into the forest, the range in daily variation decreased. Multiple regression analysis of the combined effects on stream water temperature of canopy cover, Width/Depth ratio, discharge, current velocity and water temperature revealed that canopy cover and Width/Depth were the two variables responsible for the reduced temperature observed when the streams enter the forest. In consequence, we conclude that even relatively short stretches (100-500 m) of forest alongside streams may combat the negative effects of heating of stream water and that forest planting can be a useful mitigation measure.

Investigation of microstructural changes in polyetherether-ketone films at cryogenic temperatures by positron lifetime spectroscopy

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Eftekhari, Abe; St.clair, Terry L.; Sprinkle, Danny R.

1991-01-01

Microstructural changes in Polyetherether-ketone (PEEK) films were investigated in the temperature ranges of 23 to -196 C, using Positron Lifetime Spectroscopy (PLS) technique. It was determined that the total free volume decreases by about 46 percent in amorphous PEEK samples and about 36 percent in semicrystalline PEEK samples when they are cooled down from room temperature to liquid nitrogen (LN2) temperature. If this trend in reduction in free volume with decreasing temperature continues, as expected, it is surmised that PEEK will be able to withstand cooling down to liquid hydrogen (LH2) temperature without any detrimental effect on its diffusivity for liquid hydrogen.

Friction Durability of Extremely Thin Diamond-Like Carbon Films at High Temperature

PubMed Central

Miyake, Shojiro; Suzuki, Shota; Miyake, Masatoshi

2017-01-01

To clarify the friction durability, both during and after the high-temperature heating of nanometer-thick diamond-like carbon (DLC) films, deposited using filtered cathodic vacuum arc (FCVA) and plasma chemical vapor deposition (P-CVD) methods, the dependence of the friction coefficient on the load and sliding cycles of the DLC films, were evaluated. Cluster-I consisted of a low friction area in which the DLC film was effective, while cluster-II consisted of a high friction area in which the lubricating effect of the DLC film was lost. The friction durability of the films was evaluated by statistical cluster analysis. Extremely thin FCVA-DLC films exhibited an excellent wear resistance at room temperature, but their friction durability was decreased at high temperatures. In contrast, the durability of the P-CVD-DLC films was increased at high temperatures when compared with that observed at room temperature. This inverse dependence on temperature corresponded to the nano-friction results obtained by atomic force microscopy. The decrease in the friction durability of the FCVA-DLC films at high temperatures, was caused by a complex effect of temperature and friction. The tribochemical reaction produced by the P-CVD-DLC films reduced their friction coefficient, increasing their durability at high temperatures. PMID:28772520

Friction Durability of Extremely Thin Diamond-Like Carbon Films at High Temperature.

PubMed

Miyake, Shojiro; Suzuki, Shota; Miyake, Masatoshi

2017-02-10

To clarify the friction durability, both during and after the high-temperature heating of nanometer-thick diamond-like carbon (DLC) films, deposited using filtered cathodic vacuum arc (FCVA) and plasma chemical vapor deposition (P-CVD) methods, the dependence of the friction coefficient on the load and sliding cycles of the DLC films, were evaluated. Cluster-I consisted of a low friction area in which the DLC film was effective, while cluster-II consisted of a high friction area in which the lubricating effect of the DLC film was lost. The friction durability of the films was evaluated by statistical cluster analysis. Extremely thin FCVA-DLC films exhibited an excellent wear resistance at room temperature, but their friction durability was decreased at high temperatures. In contrast, the durability of the P-CVD-DLC films was increased at high temperatures when compared with that observed at room temperature. This inverse dependence on temperature corresponded to the nano-friction results obtained by atomic force microscopy. The decrease in the friction durability of the FCVA-DLC films at high temperatures, was caused by a complex effect of temperature and friction. The tribochemical reaction produced by the P-CVD-DLC films reduced their friction coefficient, increasing their durability at high temperatures.

Effect of sintering on optical, structural and photoluminescence properties of ZnO thin films prepared by sol-gel process.

PubMed

Vishwas, M; Narasimha Rao, K; Arjuna Gowda, K V; Chakradhar, R P S

2010-09-15

Zinc oxide (ZnO) thin films have been deposited on glass substrates via sol-gel technique using zinc acetate dihydrate as precursor by spin coating of the sol at 2000 rpm. Effects of annealing temperature on optical, structural and photo luminescence properties of the deposited ZnO films have been investigated. The phase transition from amorphous to polycrystalline hexagonal wurtzite structure was observed at an annealing temperature of 400 degrees C. An average transmittance of 87% in the visible region has been obtained at room temperature. The optical transmittance has slightly increased with increase of annealing temperature. The band gap energy was estimated by Tauc's method and found to be 3.22 eV at room temperature. The optical band gap energy has decreased with increasing annealing temperature. The photoluminescence (PL) intensity increased with annealing temperature up to 200 degrees C and decreased at 300 degrees C. Copyright 2010 Elsevier B.V. All rights reserved.

Improved electrical properties after post annealing of Ba0.7Sr0.3TiO3 thin films for MIM capacitor applications

NASA Astrophysics Data System (ADS)

Rouahi, A.; Kahouli, A.; Sylvestre, A.; Jomni, F.; Defaÿ, E.; Yangui, B.

2012-11-01

Dielectric measurements have been performed on ion beam sputtering (IBS) barium strontium titanate Ba0.7Sr0.3TiO3 thin films at annealing temperatures 470 and 700 °C using impedance spectroscopy. The effect of the annealing temperature upon the electrical properties of the films is also investigated using capacitance-voltage techniques. Increasing annealing temperature suggested the increases of density and grain size, whereas the density of the trapped oxygen vacancy may be decreasing with increasing annealing temperature. The barrier height ( E a) of the oxygen vacancy decreases with increasing annealing temperature. The C- V characteristics were investigated in relation to the annealing temperature to identify the anomalous capacitance in the MIM configuration films. Among all measurement temperatures, it was observed that the data fit well by the "LGD" model. The interfacial effect and its dependence of morphology structure have been studied, and the results are discussed.

The effect of temperature, gradient, and load carriage on oxygen consumption, posture, and gait characteristics.

PubMed

Hinde, Katrina; Lloyd, Ray; Low, Chris; Cooke, Carlton

2017-03-01

The purpose of this experiment was to evaluate the effect of load carriage in a range of temperatures to establish the interaction between cold exposure, the magnitude of change from unloaded to loaded walking and gradient. Eleven participants (19-27 years) provided written informed consent before performing six randomly ordered walking trials in six temperatures (20, 10, 5, 0, -5, and -10 °C). Trials involved two unloaded walking bouts before and after loaded walking (18.2 kg) at 4 km · h -1 , on 0 and 10% gradients in 4 min bouts. The change in absolute oxygen consumption (V̇O 2 ) from the first unloaded bout to loaded walking was similar across all six temperatures. When repeating the second unloaded bout, V̇O 2 at both -5 and -10 °C was greater compared to the first. At -10 °C, V̇O 2 was increased from 1.60 ± 0.30 to 1.89 ± 0.51 L · min -1 . Regardless of temperature, gradient had a greater effect on V̇O 2 and heart rate (HR) than backpack load. HR was unaffected by temperature. Stride length (SL) decreased with decreasing temperature, but trunk forward lean was greater during cold exposure. Decreased ambient temperature did not influence the magnitude of change in V̇O 2 from unloaded to loaded walking. However, in cold temperatures, V̇O 2 was significantly higher than in warm conditions. The increased V̇O 2 in colder temperatures at the same exercise intensity is predicted to ultimately lead to earlier onset of fatigue and cessation of exercise. These results highlight the need to consider both appropriate clothing and fitness during cold exposure.

Effects of elevated temperature postharvest on color aspect, physiochemical characteristics, and aroma components of pineapple fruits.

PubMed

Liu, Chuanhe; Liu, Yan

2014-12-01

In this work, 2 separate experiments were performed to describe the influence of elevated temperature treatments postharvest on the color, physiochemical characteristics and aroma components of pineapple fruits during low-temperature seasons. The L* (lightness) values of the skin and pulp of pineapple fruits were decreased. The a* (greenness-redness) and b* (blueness-yellowness) values of the skin and pulp were all markedly increased. The elevated temperature significantly increased the contents of total soluble solids (TSS) and slightly affected contents of vitamin C (nonsignificant). Titratable acidity (TA) of pineapple fruits were notably decreased, whereas the values of TSS/TA of pineapple fruits were significantly increased. The firmness of the pineapple fruits decreased and more esters and alkenes were identified. The total relative contents of esters were increased, and the total relative contents of alkenes were decreased. © 2014 Institute of Food Technologists®

Genetic variation for farrowing rate in pigs in response to change in photoperiod and ambient temperature.

PubMed

Sevillano, C A; Mulder, H A; Rashidi, H; Mathur, P K; Knol, E F

2016-08-01

Seasonal infertility is often observed as anestrus and a lower conception rate resulting in a reduced farrowing rate (FR) during late summer and early autumn. This is often regarded as an effect of heat stress; however, we observed a reduction in the FR of sows even after correcting for ambient temperature in our data. Therefore, we added change in photoperiod in the analysis of FR considering its effect on sow fertility. Change in photoperiod was modeled using the cosine of the day of first insemination within a year. On an average, the FR decreased by 2% during early autumn with decreasing daily photoperiod compared with early summer with almost no change in daily photoperiod. It declined 0.2% per degree Celsius of ambient temperature above 19.2°C. This result is a step forward in disentangling the 2 environmental components responsible for seasonal infertility. Our next aim was to estimate the magnitude of genetic variation in FR in response to change in photoperiod and ambient temperature to explore opportunities for selecting pigs to have a constant FR throughout the year. We used reaction norm models to estimate additive genetic variation in response to change in photoperiod and ambient temperature. The results revealed a larger genetic variation at stressful environments when daily photoperiod decreased and ambient temperatures increased above 19.2°C compared with neutral environments. Genetic correlations between stressful environments and nonstressful environments ranged from 0.90 (±0.03) to 0.46 (±0.13) depending on the severity of the stress, indicating changes in expression of FR depending on the environment. The genetic correlation between responses of pigs to changes in photoperiod and to those in ambient temperature were positive, indicating that pigs tolerant to decreasing daily photoperiod are also tolerant to high ambient temperatures. Therefore, selection for tolerance to decreasing daily photoperiod should also increase tolerance to high ambient temperatures or vice versa.

Behaviour of aqueous sulfamethizole solution and temperature effects in cold plasma oxidation treatment.

PubMed

Sokolov, Alexander; Louhi-Kultanen, Marjatta

2018-06-07

The increase in volume and variety of pharmaceuticals found in natural water bodies has become an increasingly serious environmental problem. The implementation of cold plasma technology, specifically gas-phase pulsed corona discharge (PCD), for sulfamethizole abatement was studied in the present work. It was observed that sulfamethizole is easily oxidized by PCD. The flow rate and pH of the solution have no significant effect on the oxidation. Treatment at low pulse repetition frequency is preferable from the energy efficiency point of view but is more time-consuming. The maximum energy efficiency was around 120 g/kWh at half-life and around 50 g/kWh at the end of the treatment. Increasing the solution temperature from room temperature to 50 °C led to a significant reaction retardation of the process and decrease in energy efficiency. The pseudo-first order reaction rate constant (k 1 ) grows with increase in pulse repetition frequency and does not depend on pH. By contrast, decreasing frequency leads to a reduction of the second order reaction rate constant (k 2 ). At elevated temperature of 50 °C, the k 1 , k 2 values decrease 2 and 2.9 times at 50 pps and 500 pps respectively. Lower temperature of 10 °C had no effect on oxidation efficiency compared with room temperature.

Effect of interfacial disorder on exchange anisotropy in nickel manganese/nickel epitaxial bilayers

NASA Astrophysics Data System (ADS)

Lund, Michael Shane

In this thesis, the influence of interdiffusion on the structural and magnetic properties of epitaxial Ni1-xMnx/Ni bilayers has been examined. Structural characterization shows (111) oriented epitaxial layers with a 35A interdiffused layer at the Ni47Mn 53/Ni interface. This interdiffused layer is a result of the annealing step (250 C anneal for 16 hours) that is typically needed to transform NiMn into the required antiferromagnetic (AF) phase. A comparison of polarized neutron reflectometry measurements at 300 K and at 10 K show two major features as the temperature is decreased; (i) The ferromagnetic (F) moment of the sample appears to decrease with decreasing temperature, and (ii) The F layer is effectively thinner at low temperatures, i.e. the magnetic interface between the F and underlying non-F layer has a temperature dependent location. These unexpected results are confirmed by measurements of the temperature dependence of the magnetization after cooling in a demagnetized state, then applying an external field while measuring the magnetization. The magnetization decreases with decreasing temperature, consistent with a decrease in the effective F layer thickness. The effective "motion" of the magnetic interface is explained by the increasing dominance of the AF exchange interactions in the interdiffused region as the temperature is lowered. This model is further supported by the existence of memory effects and glassy behavior, which are both consistent with competing AF and F interactions in the interdiffused region. Furthermore, this interdiffusion at the AF/F interface provides a unique opportunity to assess, in a single sample, the effect of uniaxial vs. biaxial anisotropy on phenomena such as training and reversal asymmetry. As predicted by recent theory it is shown that the existence of a strong training effect, and an accompanying reversal asymmetry, can be directly correlated with the presence of biaxial exchange induced anisotropy. Finally, the dependence of exchange bias on x in Ni1-xMnx/Ni bilayers has been studied. It is found that bilayers with x ˜ 0.58 have a maximum exchange coupling and that the maximum exchange bias is achieved with just a 2 hour anneal at 250 C. This is striking and suggests that the as-deposited Ni 1-xMnx is in the AF phase. Additionally, inverted unannealed bilayers exhibit exchange bias, providing clear evidence for spontaneous magnetic ordering of Ni1-xMnx layer. This is an important find since annealing results in interdiffusion at the AF/F interface, and a subsequent reduction in the exchange bias field, it would be technologically desirable to omit this step entirely.

The stress relaxation of cement clinkers under high temperature

NASA Astrophysics Data System (ADS)

Wang, Xiufang; Bao, Yiwang; Liu, Xiaogen; Qiu, Yan

2015-12-01

The energy consumption of crushing is directly affected by the mechanical properties of cement materials. This research provides a theoretical proof for the mechanism of the stress relaxation of cement clinkers under high temperature. Compression stress relaxation under various high temperatures is discussed using a specially developed load cell, which can measure stress and displacement under high temperatures inside an autoclave. The cell shows that stress relaxation dramatically increases and that the remaining stress rapidly decreases with an increase in temperature. Mechanical experiments are conducted under various temperatures during the cooling process to study the changes in the grinding resistance of the cement clinker with temperature. The effects of high temperature on the load-displacement curve, compressive strength, and elastic modulus of cement clinkers are systematically studied. Results show that the hardening phenomenon of the clinker becomes apparent with a decrease in temperature and that post-peak behaviors manifest characteristics of the transformation from plasticity to brittleness. The elastic modulus and compressive strength of cement clinkers increase with a decrease in temperature. The elastic modulus increases greatly when the temperature is lower than 1000 °C. The compressive strength of clinkers increases by 73.4% when the temperature drops from 1100 to 800 °C.

Temperature and energy effects on secondary electron emission from SiC ceramics induced by Xe17+ ions.

PubMed

Zeng, Lixia; Zhou, Xianming; Cheng, Rui; Wang, Xing; Ren, Jieru; Lei, Yu; Ma, Lidong; Zhao, Yongtao; Zhang, Xiaoan; Xu, Zhongfeng

2017-07-25

Secondary electron emission yield from the surface of SiC ceramics induced by Xe 17+ ions has been measured as a function of target temperature and incident energy. In the temperature range of 463-659 K, the total yield gradually decreases with increasing target temperature. The decrease is about 57% for 3.2 MeV Xe 17+ impact, and about 62% for 4.0 MeV Xe 17+ impact, which is much larger than the decrease observed previously for ion impact at low charged states. The yield dependence on the temperature is discussed in terms of work function, because both kinetic electron emission and potential electron emission are influenced by work function. In addition, our experimental data show that the total electron yield gradually increases with the kinetic energy of projectile, when the target is at a constant temperature higher than room temperature. This result can be explained by electronic stopping power which plays an important role in kinetic electron emission.

Coral Uptake of Inorganic Phosphorus and Nitrogen Negatively Affected by Simultaneous Changes in Temperature and pH

PubMed Central

Godinot, Claire; Houlbrèque, Fanny

2011-01-01

The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i) at three pHT conditions (8.1, 7.8, and 7.5) and normal temperature (26°C), ii) at three temperature conditions (26°, 29°C, and 33°C) and normal pHT (8.1), and iii) at three pHT conditions (8.1, 7.8, and 7.5) and elevated temperature (33°C). After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pHT 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C) alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C) and low pHT (7.5) resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pHT = 8.1). These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification. PMID:21949839

Climate variability decreases species richness and community stability in a temperate grassland.

PubMed

Zhang, Yunhai; Loreau, Michel; He, Nianpeng; Wang, Junbang; Pan, Qingmin; Bai, Yongfei; Han, Xingguo

2018-06-26

Climate change involves modifications in both the mean and the variability of temperature and precipitation. According to global warming projections, both the magnitude and the frequency of extreme weather events are increasing, thereby increasing climate variability. The previous studies have reported that climate warming tends to decrease biodiversity and the temporal stability of community primary productivity (i.e., community stability), but the effects of the variability of temperature and precipitation on biodiversity, community stability, and their relationship have not been clearly explored. We used a long-term (from 1982 to 2014) field data set from a temperate grassland in northern China to explore the effects of the variability of mean temperature and total precipitation on species richness, community stability, and their relationship. Results showed that species richness promoted community stability through increases in asynchronous dynamics across species (i.e., species asynchrony). Both species richness and species asynchrony were positively associated with the residuals of community stability after controlling for its dependence on the variability of mean temperature and total precipitation. Furthermore, the variability of mean temperature reduced species richness, while the variability of total precipitation decreased species asynchrony and community stability. Overall, the present study revealed that species richness and species asynchrony promoted community stability, but increased climate variability may erode these positive effects and thereby threaten community stability.

Combustion and NOx emissions in deep-air-staging combustion of char in a circulating fluidized bed

NASA Astrophysics Data System (ADS)

Gong, Zhiqiang; Wang, Zhentong; Wang, Lei; Du, Aixun

2017-10-01

Combustion and NOx emissions in deep-air-staging (with higher level secondary air (SA) injection) combustion of char have been investigated in a CFB test rig. A good fluidized condition and uniform temperature distribution can be achieved with injection of higher level SA. NOx emission decreases with injection of higher level SA and the reduction effect is more obvious at higher temperature. NOx emission decreases with combustion temperature increasing for char combustion.

Complex interactive effects of ripening degree, malaxation duration and temperature on Oblica cv. virgin olive oil phenols, volatiles and sensory quality.

PubMed

Lukić, Igor; Žanetić, Mirella; Jukić Špika, Maja; Lukić, Marina; Koprivnjak, Olivera; Brkić Bubola, Karolina

2017-10-01

The interactive effects of ripening degree, malaxation duration and temperature on Oblica cv. (Olea europaea L.) virgin olive oil phenols, volatiles, and sensory quality were investigated. Olives were picked at three ripening degrees with International Olive Council indices of 0.68, 2.48 and 4.10, and processed by malaxation at 22 and 30°C, and at both temperatures for 30 and 60min. Ripening exhibited the strongest effect, and malaxation duration the weakest. Phenols were generally found to decrease during ripening; however 3,4-DHPEA-EDA and p-HPEA-EDA increased. Similar behaviour was observed for (E)-2-hexenal. Higher malaxation temperature induced an increase in particular important phenols and C6 alcohols, while C6 aldehydes mostly decreased. Interactions between the factors were established, mostly between ripening degree and malaxation temperature: the effect of the latter was most pronounced for ripe olives, especially for 3,4-DHPEA-EDA, p-HPEA-EDA and C6 volatiles. Sensory attributes were generally in agreement with the chemical composition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of growth temperature and winter duration on leaf phenology of a spring ephemeral (Gagea lutea) and a summergreen forb (Maianthemum dilatatum).

PubMed

Yoshie, Fumio

2008-09-01

Effects of growth temperature and winter duration on leaf longevity were compared between a spring ephemeral, Gagea lutea, and a forest summergreen forb, Maianthemum dilatatum. The plants were grown at day/night temperatures of 25/20 degrees C and 15/10 degrees C after a chilling treatment for variable periods at 2 degrees C. The temperature regime of 25/20 degrees C was much higher than the mean air temperatures for both species in their native habitats. Warm temperature of 25/20 degrees C and/or long chilling treatment shortened leaf longevity in G. lutea, but not in M. dilatatum. The response of G. lutea was consistent with that reported for other spring ephemerals. Air temperature increases as the vegetative season progresses. The decrease in leaf longevity in G. lutea under warm temperature condition ensures leaf senescence in summer, an unfavorable season for its growth. This also implies that early leaf senescence could occur in years with early summers. Warm spring temperatures have been shown to accelerate the leafing-out of forest trees. The decrease in leaf longevity due to warm temperature helps synchronize the period of leaf senescence roughly with the time of the forest canopy leaf-out. Prolonged winter due to late snowmelt has been shown to shorten the vegetative period for spring ephemerals. The decrease in leaf longevity due to long chilling treatment would correspond with this shortened vegetative period.

[Study of the effect of heat source separation distance on plasma physical properties in laser-pulsed GMAW hybrid welding based on spectral diagnosis technique].

PubMed

Liao, Wei; Hua, Xue-Ming; Zhang, Wang; Li, Fang

2014-05-01

In the present paper, the authors calculated the plasma's peak electron temperatures under different heat source separation distance in laser- pulse GMAW hybrid welding based on Boltzmann spectrometry. Plasma's peak electron densities under the corresponding conditions were also calculated by using the Stark width of the plasma spectrum. Combined with high-speed photography, the effect of heat source separation distance on electron temperature and electron density was studied. The results show that with the increase in heat source separation distance, the electron temperatures and electron densities of laser plasma did not changed significantly. However, the electron temperatures of are plasma decreased, and the electron densities of are plasma first increased and then decreased.

Experimental evaluation of a TF30-P-3 turbofan engine in an altitude facility: Effect of steady-state temperature distortion

NASA Technical Reports Server (NTRS)

Braithwaite, W. M.

1973-01-01

The effects of circumferential distortion of the total temperature entering 25, 50, and 75 percent of the inlet circumferential annulus of a turbofan engine were determined. Complete compressor stall resulted from distortions of from 14 to 20 percent of the face averaged temperature. Increasing the temperature level in one sector resulted in that sector moving toward stall by decreasing the equivalent rotor speeds while the pressure ratio remained approximately constant. Stall originated as a rotating zone in the low-pressure compressor which resulted as a terminal stall in the high-pressure compressor. Decreasing the Reynolds number index to 0.25 from 0.5 reduced the required distortion for stall by 50 percent for the conditions investigated.

Hall effect in high- Tc Y 1Ba 2Cu 3O 7-δ superconductor

NASA Astrophysics Data System (ADS)

Vezzoli, G. C.; Burke, T.; Moon, B. M.; Lalevic, B.; Safari, A.; Sundar, H. G. K.; Bonometti, R.; Alexander, C.; Rau, C.; Waters, K.

1989-04-01

We have performed point-by-point and continuous Hall effect experiments as a function of temperature in polycrystalline Y 1Ba 2Cu 3O 7-δ. We have shown that the positive Hall constant shows an abrupt increase upon decreasing temperature at a value just above Tc. This temperature corresponds to where the resistance versus temperature data deviates from linearity. At very high fields of 6.8 and 15 T we observe a subsequent decrease in RH. We interpret these data as supportive of a contribution toward the superconductivity mechanism arising from internal excitions or change transfer excitations such that the bound exciton concentration increases near Tc at the expense of positive carries which are reflected in both bound and free holes.

Effect of elevated temperature on soil hydrothermal regimes and growth of wheat crop.

PubMed

Pramanik, P; Chakrabarti, Bidisha; Bhatia, Arti; Singh, S D; Maity, A; Aggarwal, P; Krishnan, P

2018-03-14

An attempt has been made to study the effect of elevated temperature on soil hydrothermal regimes and winter wheat growth under simulated warming in temperature gradient tunnel (TGT). Results showed that bulk density (BDs) of 0, 0.9, and 2.5 °C were significantly different whereas BDs of 2.8 and 3.5 °C were not significantly different. Water filled pore space (WFPS) was maximum at 3.5 °C temperature rise and varied between 43.80 and 98.55%. Soil surface temperature (ST) at different dates of sowing increased with rise in sensor temperature and highest ST was observed at S5 sensors (3.5 °C temperature rise). Temperature and its difference were high for the top soil, and were stable for the deep soil. Photosynthesis rate (μmol CO 2 m -2  s -1 ) of wheat was lower at higher temperature in different growth stages of wheat. In wheat, stomatal conductance declined from 0.67 to 0.44 mol m -2  s -1 with temperature rise. Stomatal conductance decreased with increase in soil temperature and gravimetric soil moisture content (SWC). In TGT, 0 °C temperature rise showed highest root weight density (RWD) (5.95 mg cm -3 ); whereas, 2.8 and 3.5 °C showed lowest RWD (4.90 mg cm -3 ). Harvest index was maximum (0.37) with 0 °C temperature rise, and it decreased with increase in temperature, which indicated that both grain and shoot biomass decreased with increase in temperature. Intensive studies are needed to quantify the soil hydrothermal regimes inside TGT along with the crop growth parameters.

Effects of vacuum rapid thermal annealing on the electrical characteristics of amorphous indium gallium zinc oxide thin films

NASA Astrophysics Data System (ADS)

Lee, Hyun-Woo; Cho, Won-Ju

2018-01-01

We investigated the effects of vacuum rapid thermal annealing (RTA) on the electrical characteristics of amorphous indium gallium zinc oxide (a-IGZO) thin films. The a-IGZO films deposited by radiofrequency sputtering were subjected to vacuum annealing under various temperature and pressure conditions with the RTA system. The carrier concentration was evaluated by Hall measurement; the electron concentration of the a-IGZO film increased and the resistivity decreased as the RTA temperature increased under vacuum conditions. In a-IGZO thin-film transistors (TFTs) with a bottom-gate top-contact structure, the threshold voltage decreased and the leakage current increased as the vacuum RTA temperature increased. As the annealing pressure decreased, the threshold voltage decreased, and the leakage current increased. X-ray photoelectron spectroscopy indicated changes in the lattice oxygen and oxygen vacancies of the a-IGZO films after vacuum RTA. At higher annealing temperatures, the lattice oxygen decreased and oxygen vacancies increased, which suggests that oxygen was diffused out in a reduced pressure atmosphere. The formation of oxygen vacancies increased the electron concentration, which consequently increased the conductivity of the a-IGZO films and reduced the threshold voltage of the TFTs. The results showed that the oxygen vacancies and electron concentrations of the a-IGZO thin films changed with the vacuum RTA conditions and that high-temperature RTA treatment at low pressure converted the IGZO thin film to a conductor.

Theoretical and experimental study on reabsorption effect and temperature characteristic of a quasi-three-level 946nm Nd:YAG laser

NASA Astrophysics Data System (ADS)

Huang, Jing; Wan, Yuan; Chen, Weibiao

2015-02-01

The influence of temperature and incident pump power on reabsorption loss is theoretically discussed. Temperature characteristic and reabsorption loss rate of a diode-pumped quasi-three-level 946 nm Nd:YAG laser are investigated. Reabsorption effect has a significant impact on laser performance. The results indicate that reabsorption loss increases as the working temperature rises and decreases with the increased incident pump power.

Effect of the Aging Temperature of Steel on the Parameters of Fatigue Resistance and Microstrain

NASA Astrophysics Data System (ADS)

Myl'nikov, V. V.; Romanov, A. D.; Shetulov, D. I.; Khlybov, A. A.

2016-07-01

The interrelation of the parameters of microplastic strain, the slope of the left-hand branch of the fatigue curve, and the fatigue limit of a maraging steel is studied. The growth in the microplastic strain is shown to match the growth in the fatigue limit and the decrease in the slope of the left-hand branch of the fatigue curve. The strength of the steel decreases with decrease in the temperature of post-quenching aging.

Effects of pressure, cold and gloves on hand skin temperature and manual performance of divers.

PubMed

Zander, Joanna; Morrison, James

2008-09-01

Cold water immersion and protective gloves are associated with decreased manual performance. Although neoprene gloves slow hand cooling, there is little information on whether they provide sufficient protection when diving in cold water. Nine divers wearing three-fingered neoprene gloves and dry suits were immersed in water at 25 and 4 degrees C, at depths of 0.4 msw (101 kPa altitude adjusted) and 40 msw (497 kPa) in a hyperbaric chamber. Skin temperatures were measured at the fingers, hand, forearm, chest and head. Grip strength, tactile sensitivity and manual dexterity were measured at three time intervals. There was an exponential decay in finger and back of hand skin temperatures with exposure time in 4 degrees C water. Finger and back of hand skin temperatures were lower at 40 msw than at 0.4 msw (P < 0.05). There was no effect of pressure or temperature on grip strength. Tactile sensitivity decreased linearly with finger skin temperature at both pressures. Manual dexterity was not affected by finger skin temperature at 0.4 msw, but decreased with fall in finger skin temperature at 40 msw. Results show that neoprene gloves do not provide adequate thermal protection in 4 degrees C water and that impairment of manual performance is dependent on the type of task, depth and exposure time.

Piezoresistive silicon pressure sensors in cryogenic environment

NASA Technical Reports Server (NTRS)

Kahng, Seun K.; Chapman, John J.

1989-01-01

This paper presents data on low-temperature measurements of silicon pressure sensors. It was found that both the piezoresistance coefficients and the charge-carrier mobility increase with decreasing temperature. For lightly doped semiconductor materials, the density of free charge carriers decreases with temperature and can freeze out eventually. However, the effect of carrier freeze-out can be minimized by increasing the impurity content to higher levels, at which the temperature dependency of piezoresistance coefficients is reduced. An impurity density of 1 x 10 to the 19th/cu cm was found to be optimal for cryogenic applications of pressure sensor dies.

Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps

NASA Technical Reports Server (NTRS)

Al-Maaitah, Ayman A.; Nayfeh, Ali, H.; Ragab, Saad A.

1989-01-01

The effect of wall cooling on the two-dimensional linear stability of subsonic flows over two-dimensional surface imperfections is investigated. Results are presented for flows over smooth humps and backward-facing steps with Mach numbers up to 0.8. The results show that, whereas cooling decreases the viscous instability, it increases the shear-layer instability and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80 pct and 60 pct of the adiabatic wall temperature, respectively. Increasing the Mach number decreases the effectiveness of cooling slightly and reduces the optimum wall temperature.

Effects of hydrothermal treatment on the pyrolysis behavior of Chinese fan palm.

PubMed

Yao, Zhongliang; Ma, Xiaoqian

2018-01-01

The effect of hydrothermal treatment (HTT) on Chinese fan palm pyrolysis was investigated. It indicated that HTT could effectively remove a large portion of alkali/alkaline earth metals and disrupt the chemical structure to a certain extent. HTT delayed the initial decomposition temperature but accelerated the pyrolysis process completely. HTT also increased the relative contents of both sugars and hydrocarbons in pyrolysis. At 210°C, HTT had the most significant promotion effect on the sugars formation with the relative content of 30.58%. While, The relative content of phenols, acids, furans, aldehydes, esters and CO 2 decreased more or less after HTT. With increasing pyrolysis temperature, the relative content of most groups of chemicals except hydrocarbons decreased. Response contours were analyzed to find the optimal reaction conditions for generating acids, phenols, sugars and hydrocarbons, respectively. The results indicated both pyrolysis temperature and HTT temperature had distinct influence on relative contents of products. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of synthesis methods with different annealing temperatures on micro structure, cations distribution and magnetic properties of nano-nickel ferrite

NASA Astrophysics Data System (ADS)

El-Sayed, Karimat; Mohamed, Mohamed Bakr; Hamdy, Sh.; Ata-Allah, S. S.

2017-02-01

Nano-crystalline NiFe2O4 was synthesized by citrate and sol-gel methods at different annealing temperatures and the results were compared with a bulk sample prepared by ceramic method. The effect of methods of preparation and different annealing temperatures on the crystallize size, strain, bond lengths, bond angles, cations distribution and degree of inversions were investigated by X-ray powder diffraction, high resolution transmission electron microscope, Mössbauer effect spectrometer and vibrating sample magnetometer. The cations distributions were determined at both octahedral and tetrahedral sites using both Mössbauer effect spectroscopy and a modified Bertaut method using Rietveld method. The Mössbauer effect spectra showed a regular decrease in the hyperfine field with decreasing particle size. Saturation magnetization and coercivity are found to be affected by the particle size and the cations distribution.

Crossover of Microscopic Dynamics in Metallic Supercooled Liquid Observed by NMR

NASA Astrophysics Data System (ADS)

Wu, Yue; Li, Lilong

2004-03-01

Nuclear magnetic resonance (NMR) is used to characterize local atomic motions in the glassy and supercooled liquid states of the bulk metallic glass system Pd_43Ni_10Cu_27P_20. It is shown that NMR is very effective in detecting local motions such as vibrations in metallic systems. The temperature dependence of the Knight shift reveals that certain local atomic motion decreases rapidly below a crossover temperature T_c. Above Tc as well as below the glass transition temperature Tg the mean-squared amplitude of local motions is shown to depend linearly on the temperature. The observed rapid decrease below Tc cannot be explained by heterogeneity effects. It reveals that qualitative changes of microscopic properties in the supercooled liquid take place at temperatures significantly above T_g. The observed phenomenon can be explained in terms of a rapid disappearance of certain local motions below Tc as suggested by the mode-coupling theory.

Effect of different temperature-time combinations on lipid and protein oxidation of sous-vide cooked lamb loins.

PubMed

Roldan, Mar; Antequera, Teresa; Armenteros, Monica; Ruiz, Jorge

2014-04-15

Forty-five lamb loins were subjected to sous-vide cooking at different combinations of temperature (60, 70 and 80 °C) and time (6, 12 and 24 h) to assess the effect on the oxidative stability of lipids and proteins. Heating induced both lipid and protein oxidation in lamb loins. Higher cooking temperature-time combinations increased conjugated dienes and decreased thiobarbituric reactive substances (TBARS) values and hexanal. Total protein carbonyls increased throughout time at all cooking temperatures considered, while α-aminoadipic (AAS) and γ-glutamic semialdehydes (GGS) increased when cooking at 60 °C but not at 80 °C. Links between the decrease in secondary compounds from lipid oxidation due to cooking at higher temperatures and for longer times with the increased levels of 3-methylbutanal and greater differences between total protein carbonyls and AAS plus GGS were hypothesised. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of a compact freeze vacuum drying for jelly fish (Schypomedusae)

NASA Astrophysics Data System (ADS)

Alhamid, M. Idrus; Yulianto, M.; Nasruddin

2012-06-01

A new design of a freeze vacuum drying with internal cooling and heater from condenser's heat loss was built and tested. The dryer was used to dry jelly fish (schypomedusae), to study the effect of drying parameters such as the temperature within the drying chamber on mass losses (evaporation) during the freezing stage and the moisture ratio at the end of the drying process. The midili thin layer mathematical drying model was used to estimate and predict the moisture ratio curve based on different drying chamber temperatures. This experiment shows that decreasing the drying chamber temperature with constant pressure results in less mass loss during the freezing stage Drying time was reduced with an increase in drying temperature. Decreasing the drying chamber temperature results in lower pressure saturation of the material has no effect of drying chamber pressure on mass transfer.

Temperature Effects and Compensation-Control Methods

PubMed Central

Xia, Dunzhu; Chen, Shuling; Wang, Shourong; Li, Hongsheng

2009-01-01

In the analysis of the effects of temperature on the performance of microgyroscopes, it is found that the resonant frequency of the microgyroscope decreases linearly as the temperature increases, and the quality factor changes drastically at low temperatures. Moreover, the zero bias changes greatly with temperature variations. To reduce the temperature effects on the microgyroscope, temperature compensation-control methods are proposed. In the first place, a BP (Back Propagation) neural network and polynomial fitting are utilized for building the temperature model of the microgyroscope. Considering the simplicity and real-time requirements, piecewise polynomial fitting is applied in the temperature compensation system. Then, an integral-separated PID (Proportion Integration Differentiation) control algorithm is adopted in the temperature control system, which can stabilize the temperature inside the microgyrocope in pursuing its optimal performance. Experimental results reveal that the combination of microgyroscope temperature compensation and control methods is both realizable and effective in a miniaturized microgyroscope prototype. PMID:22408509

Differential effects of dopamine and opioid receptor blockade on motivated Coca-Cola drinking behavior and associated changes in brain, skin and muscle temperatures

PubMed Central

Kiyatkin, Eugene A.

2010-01-01

Although pharmacological blockade of both dopamine (DA) and opiate receptors has an inhibiting effect on appetitive motivated behaviors, it is still unclear which physiological mechanisms affected by these treatments underlie the behavioral deficit. To clarify this issue, we examined how pharmacological blockade of either DA (SCH23390 + eticlopride at 0.2 mg/kg each) or opioid receptors (naloxone 1 mg/kg) affects motor activity and temperature fluctuations in the nucleus acumens (NAcc), temporal muscle, and facial skin associated with motivated Coca-Cola drinking behavior in rats. In drug-free conditions, presentation of a cup containing 5 ml of Coca-Cola induced locomotor activation and rapid NAcc temperature increases, which both transiently decreased during drinking, and phasically increased again after the cup was emptied. Muscle temperatures followed this pattern, but increases were weaker and more delayed than those in the NAcc. Skin temperature rapidly dropped after cup presentation, remained at low levels during consumption, and slowly restored during post-consumption behavioral activation. By itself, DA receptor blockade induced robust decrease in spontaneous locomotion, moderate increases in brain and muscle temperatures, and a relative increase in skin temperatures, suggesting metabolic activation coupled with adynamia. Following this treatment (∼180 min), motor activation to cup presentation and Coca-Cola consumption were absent, but rats showed NAcc and muscle temperature increases following cup presentation comparable to control. Therefore, DA receptor blockade does not affect significantly central and peripheral autonomic responses to appetitive stimuli, but eliminates their behavior-activating effects, thus disrupting appetitive behavior and blocking consumption. Naloxone alone slightly decreased brain and muscle temperatures and increased skin temperatures, pointing at the enhanced heat loss and possible minor inhibition of basal metabolic activity. This treatment (∼60 min) had minimal effects on the latencies of drinking, but increased its total duration, with licking interrupted by pauses and retreats. This behavioral attenuation was coupled with weaker than in control locomotor activation and diminished temperature fluctuations in each recording location. Therefore, attenuation of normal behavioral and physiological responses to appetitive stimuli appears to underlie modest inhibiting effects of opiate receptor blockade on motivated behavior and consumption. PMID:20167257

Temperature effect on betavoltaic microbatteries based on Si and GaAs under 63Ni and 147Pm irradiation

NASA Astrophysics Data System (ADS)

Wang, Hao; Tang, Xiao-bin; Liu, Yun-Peng; Xu, Zhi-Heng; Liu, Min; Chen, Da

2015-09-01

The effect of temperature on the output performance of four different types of betavoltaic microbatteries was investigated experimental and theoretical. Si and GaAs were selected as the energy conversion devices in four types of betavoltaic microbatteries, and 63Ni and 147Pm were used as beta sources. Current density-voltage curves were determined at a temperature range of 213.15-333.15 K. A simplified method was used to calculate the theoretical parameters of the betavoltaic microbatteries considering the energy loss of beta particles for self-absorption of radioactive source, the electron backscatter effect of different types of semiconductor materials, and the absorption of dead layer. Both the experimental and theoretical results show that the short-circuit current density increases slightly and the open-circuit voltage (VOC) decreases evidently with the increase in temperature. Different combinations of energy conversion devices and beta sources cause different effects of temperature on the microbatteries. In the approximately linear range, the VOC sensitivities caused by temperature for 63Ni-Si, 63Ni-GaAs, 147Pm-Si, and 147Pm-GaAs betavoltaic microbatteries were -2.57, -5.30, -2.53, and -4.90 mV/K respectively. Both theoretical and experimental energy conversion efficiency decreased evidently with the increase in temperature.

Temperature Dependence of Field-Effect Mobility in Organic Thin-Film Transistors: Similarity to Inorganic Transistors.

PubMed

Okada, Jun; Nagase, Takashi; Kobayashi, Takashi; Naito, Hiroyoshi

2016-04-01

Carrier transport in solution-processed organic thin-film transistors (OTFTs) based on dioctylbenzothienobenzothiophene (C8-BTBT) has been investigated in a wide temperature range from 296 to 10 K. The field-effect mobility shows thermally activated behavior whose activation energy becomes smaller with decreasing temperature. The temperature dependence of field-effect mobility found in C8-BTBT is similar to that of others materials: organic semiconducting polymers, amorphous oxide semiconductors and hydrogenated amorphous silicon. These results indicate that hopping transport between isoenergetic localized states becomes dominated in a low temperature regime in these materials.

Effect of water injection on nitric oxide emissions of a gas turbine combustor burning natural gas fuel

NASA Technical Reports Server (NTRS)

Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

1973-01-01

The effect of direct water injection on the exhaust gas emissions of a turbojet combustor burning natural gas fuel was investigated. The results are compared with the results from similar tests using ASTM Jet-A fuel. Increasing water injection decreased the emissions of oxides of nitrogen (NOX) and increased the emissions of carbon monoxide and unburned hydrocarbons. The greatest percentage decrease in NOX with increasing water injection was at the lowest inlet-air temperature tested. The effect of increasing inlet-air temperature was to decrease the effect of the water injection. The reduction in NOX due to water injection was almost identical to the results obtained with Jet-A fuel. However, the emission indices of unburned hydrocarbons, carbon monoxide, and percentage nitric oxide in NOX were not.

Effects of outside air temperature on the preparation of antineoplastic drug solutions in biological safety cabinets.

PubMed

Umemura, Masayuki; Itoh, Akio; Ando, Yuichi; Yamada, Kiyofumi; Wakiya, Yoshifumi; Nabeshima, Toshitaka

2015-08-01

In Japan, biological safety cabinets are commonly used by medical staff to prepare antineoplastic agents. At the Division of Chemotherapy for Outpatients, Nagoya University Hospital, a class II B2 biological safety cabinet is used. The temperature inside this biological safety cabinet decreases in winter. In this study, we investigated the effect of low outside air temperature on the biological safety cabinet temperature, time required to admix antineoplastic agents, and accuracy of epirubicin weight measurement. Studies were conducted from 1 January to 31 March 2008 (winter). The outside air temperature near the biological safety cabinet intake nozzle was compared with the biological safety cabinet temperature. The correlation between the outside air temperature and the biological safety cabinet temperature, time for cyclophosphamide and gemcitabine solubilization, and accuracy of epirubicin weight measurement were investigated at low and high biological safety cabinet temperatures. The biological safety cabinet temperature correlated with the outside air temperature of 5-20℃ (p < 0.0001). Compared to cyclophosphamide and gemcitabine solubilization in the biological safety cabinet at 25℃, solubilization at 10℃ was significantly delayed (p < 0.01 and p < 0.0001, respectively). Measurement of epirubicin weight by using a syringe lacked accuracy because of epirubicin's high viscosity at low temperatures (p < 0.01). These results suggest that the biological safety cabinet temperature decreases when cool winter air is drawn into the biological safety cabinet, affecting the solubilization of antineoplastic agents. We suggest that a decrease in biological safety cabinet temperature may increase the time required to admix antineoplastic agents, thereby increasing the time for which outpatients must wait for chemotherapy. © The Author(s) 2014.

Laboratory investigation of the factors impact on bubble size, pore blocking and enhanced oil recovery with aqueous Colloidal Gas Aphron.

PubMed

Shi, Shenglong; Wang, Yefei; Li, Zhongpeng; Chen, Qingguo; Zhao, Zenghao

Colloidal Gas Aphron as a mobility control in enhanced oil recovery is becoming attractive; it is also designed to block porous media with micro-bubbles. In this paper, the effects of surfactant concentration, polymer concentration, temperature and salinity on the bubble size of the Colloidal Gas Aphron were studied. Effects of injection rates, Colloidal Gas Aphron fluid composition, heterogeneity of reservoir on the resistance to the flow of Colloidal Gas Aphron fluid through porous media were investigated. Effects of Colloidal Gas Aphron fluid composition and temperature on residual oil recovery were also studied. The results showed that bubble growth rate decreased with increasing surfactant concentration, polymer concentration, and decreasing temperature, while it decreased and then increased slightly with increasing salinity. The obvious increase of injection pressure was observed as more Colloidal Gas Aphron fluid was injected, indicating that Colloidal Gas Aphron could block the pore media effectively. The effectiveness of the best blend obtained through homogeneous sandpack flood tests was modestly improved in the heterogeneous sandpack. The tertiary oil recovery increased 26.8 % by Colloidal Gas Aphron fluid as compared to 20.3 % by XG solution when chemical solution of 1 PV was injected into the sandpack. The maximum injected pressure of Colloidal Gas Aphron fluid was about three times that of the XG solution. As the temperature increased, the Colloidal Gas Aphron fluid became less stable; the maximum injection pressure and tertiary oil recovery of Colloidal Gas Aphron fluid decreased.

Temperature and population density effects on locomotor activity of Musca domestica (Diptera: Muscidae).

PubMed

Schou, T M; Faurby, S; Kjærsgaard, A; Pertoldi, C; Loeschcke, V; Hald, B; Bahrndorff, S

2013-12-01

The behavior of ectotherm organisms is affected by both abiotic and biotic factors. However, a limited number of studies have investigated the synergistic effects on behavioral traits. This study examined the effect of temperature and density on locomotor activity of Musca domestica (L.). Locomotor activity was measured for both sexes and at four densities (with mixed sexes) during a full light and dark (L:D) cycle at temperatures ranging from 10 to 40°C. Locomotor activity during daytime increased with temperature at all densities until reaching 30°C and then decreased. High-density treatments significantly reduced the locomotor activity per fly, except at 15°C. For both sexes, daytime activity also increased with temperature until reaching 30 and 35°C for males and females, respectively, and thereafter decreased. Furthermore, males showed a significantly higher and more predictable locomotor activity than females. During nighttime, locomotor activity was considerably lower for all treatments. Altogether the results of the current study show that there is a significant interaction of temperature and density on daytime locomotor activity of M. domestica and that houseflies are likely to show significant changes in locomotor activity with change in temperature.

Melatonin induces opposite effects on order and dynamics of anionic DPPG model membranes

NASA Astrophysics Data System (ADS)

Sahin, Ipek; Severcan, Feride; Kazancı, Nadide

2007-05-01

The temperature and concentration induced effects of melatonin on anionic dipalmitoyl phosphatidylglycerol (DPPG) multilamellar liposomes (MLVs) were investigated by using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The results show that melatonin does not perturb the phase transition profile, while a decrease in the main transition temperature ( Tm) is noticed at high melatonin concentrations (15, 24 and 30 mol %). Low concentrations of melatonin (3, 6 and 9 mol %) decrease the frequency of the CH 2 stretching mode, implying an ordering effect, whilst high concentrations of melatonin disorders system both in the gel and liquid crystalline phases. Furthermore, at low and high concentrations, melatonin also causes opposite effect on membrane dynamics. The bandwidth of the CH 2 stretching modes decreases at low concentrations, implying a decrease in the dynamics, while increasing it at high concentrations. Furthermore, it causes significant decrease in the frequency of the C dbnd O stretching and PO2- antisymmetric double bond stretching bands of DPPG for all concentrations both in the gel and liquid crystalline phases, which indicates strong hydrogen bonding around these functional groups.

Short-term effects of air temperature on plasma metabolite concentrations in patients undergoing cardiac catheterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hampel, Regina, E-mail: regina.hampel@helmholtz-mu

Background: Epidemiological studies have shown associations between air temperature and cardiovascular health outcomes. Metabolic dysregulation might also play a role in the development of cardiovascular disease. Objectives: To investigate short-term temperature effects on metabolites related to cardiovascular disease. Methods: Concentrations of 45 acylcarnitines, 15 amino acids, ketone bodies and total free fatty acids were available in 2869 participants from the CATHeterization GENetics cohort recruited at the Duke University Cardiac Catheterization Clinic (Durham, NC) between 2001 and 2007. Ten metabolites were selected based on quality criteria and cluster analysis. Daily averages of meteorological variables were obtained from the North American Regionalmore » Reanalysis project. Immediate, lagged, and cumulative temperature effects on metabolite concentrations were analyzed using (piecewise) linear regression models. Results: Linear temperature effects were found for glycine, C16-OH:C14:1-DC, and aspartic acid/asparagine. A 5 °C increase in temperature was associated with a 1.8% [95%-confidence interval: 0.3%; 3.3%] increase in glycine (5-day average), a 3.2% [0.1%; 6.3%] increase in C16-OH:C14:1-DC (lag of four days), and a −1.4% [−2.4%; −0.3%] decrease in aspartic acid/asparagine (lag of two days). Non-linear temperature effects were observed for alanine and total ketone bodies with breakpoint of 4 °C and 20 °C, respectively. Both a 5 °C decrease in temperature on colder days (<4 °C)and a 5 °C increase in temperature on warmer days (≥4 °C) were associated with a four day delayed increase in alanine by 6.6% [11.7; 1.8%] and 1.9% [0.3%; 3.4%], respectively. For ketone bodies we found immediate (0-day lag) increases of 4.2% [−0.5%; 9.1%] and 12.3% [0.1%; 26.0%] associated with 5 °C decreases on colder (<20 °C) days and 5 °C increases on warmer days (≥20 °C), respectively. Conclusions: We observed multiple effects of air temperature on metabolites several of which are reported to be involved in cardiovascular disease. Our findings might help to understand the link between air temperature and cardiovascular disease. - Highlights: • Certain metabolites are assumed to be novel biomarkers for cardiovascular disease. • First study investigating associations between air temperature and metabolites. • Short-term effects of temperature on amino acids, ketone bodies and acylcarnitines. • Our findings may help to understand the link between temperature and cardiovascular disease.« less

Effect of Ti4+ doping on magnetic properties of charge ordered Bi0.3Ca0.7MnO3

NASA Astrophysics Data System (ADS)

Yadav, Kamlesh; Singh, M. P.; Razavi, F. S.; Varma, G. D.

2017-07-01

The effect of Ti doping in Bi0.3Ca0.7Mn1-x Ti x O3 (where x  =  0.0, 0.015, 0.03, 0.05, 0.08, 0.12 and 0.16) on structural, magnetic and transport properties have been studied. The charge-ordering temperature (T CO) decreases gradually with increasing Ti doping content, and finally disappears completely for x  =  0.12. The Neel temperature (T N) also decreases with increasing Ti doping content. A transition to a cluster glass like state is observed at T  ⩽  T N. The zero field cooled/field cooled (ZFC/FC) magnetization decreases at high temperature (T  >  200 K) with increasing Ti content, whereas an opposite trend is observed at low temperature (T  <  200 K). Small exchange bias effect is also observed for x  =  0.08 at 10 K. The resistivity increases with increasing Ti doping content. The disorder induced by Ti doping on the Mn site plays a key role in explaining the observed magnetic and electrical properties.

The Effect of MHD on Free Convection with Periodic Temperature and Concentration in the Presence of Thermal Radiation and Chemical Reaction

NASA Astrophysics Data System (ADS)

Zigta, B.; Koya, P. R.

2017-12-01

This paper studies the effect of magneto hydrodynamics on unsteady free convection between a pair of infinite vertical Couette plates. The temperature of the plates and concentration between the plates vary with time. Convection between the plates is considered in the presence of thermal radiation and chemical reaction. The solution is obtained using perturbation techniques. These techniques are used to transform nonlinear coupled partial differential equations to a system of ordinary differential equations. The resulting equations are solved analytically. The solution is expressed in terms of power series with some small parameter. The effect of various parameters, viz., velocity, temperature and concentration, has been discussed. Mat lab code simulation study is carried out to support the theoretical results. The result shows that as the thermal radiation parameter R increases, the temperature decreases near the moving porous plate while it approaches to a zero in the region close to the boundary layer of the stationary plate. Moreover, as the modified Grashof number, i.e., based on concentration difference, increases, the velocity of the fluid flow increases hence the concentration decreases. An increase in both the chemical reaction parameter and Schmidt number results in decreased concentration.

[Microclimate and comfortable degree of Shanghai urban open spaces in summer].

PubMed

Cao, Dan; Zhou, Li-chen; Mao, Yi-wei; Li, Yin; Liu, Yi-ning; Wang, Tian-hou

2008-08-01

Based on the observation data of air temperature, relative humidity, wind speed, and solar radiation from May to August 2006, the regulation effects of five types of open spaces (square, fountain, grassplot, corridor, and woodland) in Shanghai urban districts on the microclimate were analyzed, and discomfort index (DI) was introduced to evaluate the effects of these five types of open spaces on human body' s comfortable degree. The results showed that there existed definite differences in the air temperature and relative humidity among the open spaces, with the mean temperature decreased in the order of square > grassplot > fountain > corridor > woodland, and the mean relative humidity decreased in the order of woodland > corridor > fountain > grassplot > square. The area of the square, the wind speed and direction near the fountain, the grass species on the grass-plot, the width and tree coverage of the corridor, and the tree coverage and canopy height of the woodland had significant correlations with the microclimate parameters of corresponding open spaces. Comparing with other three types of open spaces, woodland and corridor had better regulation effects on the microclimate via shading, decreasing air temperature, and increasing relative humidity.

Emissions of an AVCO Lycoming 0-320-DIAD air cooled light aircraft engine as a function of fuel-air ratio, timing, and air temperature and humidity

NASA Technical Reports Server (NTRS)

Meng, P. R.; Skorobatckyi, M.; Cosgrove, D. V.; Kempke, E. E., Jr.

1976-01-01

A carbureted aircraft engine was operated over a range of test conditions to establish the exhaust levels over the EPA seven-mode emissions cycle. Baseline (full rich production limit) exhaust emissions at an induction air temperature of 59 F and near zero relative humidity were 90 percent of the EPA standard for HC, 35 percent for NOx, and 161 percent for CO. Changes in ignition timing around the standard 25 deg BTDC from 30 deg BTDC to 20 deg BTDC had little effect on the exhaust emissions. Retarding the timing to 15 deg BTDC increased both the HC and CO emissions and decreased NOx emissions. HC and CO emissions decreased as the carburetor was leaned out, while NOx emissions increased. The EPA emission standards were marginally achieved at two leanout conditions. Variations in the quantity of cooling air flow over the engine had no effect on exhaust emissions. Temperature-humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emissions decreased.

Effects of Vacancy Cluster Defects on Electrical and Thermodynamic Properties of Silicon Crystals

PubMed Central

Huang, Pei-Hsing; Lu, Chi-Ming

2014-01-01

A first-principle plane-wave pseudopotential method based on the density function theory (DFT) was employed to investigate the effects of vacancy cluster (VC) defects on the band structure and thermoelectric properties of silicon (Si) crystals. Simulation results showed that various VC defects changed the energy band and localized electron density distribution of Si crystals and caused the band gap to decrease with increasing VC size. The results can be ascribed to the formation of a defect level produced by the dangling bonds, floating bonds, or high-strain atoms surrounding the VC defects. The appearance of imaginary frequencies in the phonon spectrum of defective Si crystals indicates that the defect-region structure is dynamically unstable and demonstrates phase changes. The phonon dispersion relation and phonon density of state were also investigated using density functional perturbation theory. The obtained Debye temperature (θ D) for a perfect Si crystal had a minimum value of 448 K at T = 42 K and a maximum value of 671 K at the high-temperature limit, which is consistent with the experimental results reported by Flubacher. Moreover, the Debye temperature decreased with increases in the VC size. VC defects had minimal effects on the heat capacity (C v) value when temperatures were below 150 K. As the temperature was higher than 150 K, the heat capacity gradually increased with increasing temperature until it achieved a constant value of 11.8 cal/cell·K. The heat capacity significantly decreased as the VC size increased. For a 2 × 2 × 2 superlattice Si crystal containing a hexagonal ring VC (HRVC10), the heat capacity decreased by approximately 17%. PMID:24526923

Temperature-sensitive release of prostaglandin E₂ and diminished energy requirements in synovial tissue with postoperative cryotherapy: a prospective randomized study after knee arthroscopy.

PubMed

Stålman, Anders; Berglund, Lukas; Dungnerc, Elisabeth; Arner, Peter; Felländer-Tsai, Li

2011-11-02

Local external cooling of the surgical field after joint surgery is intended to enhance recovery and to facilitate the use of outpatient surgery by reducing pain and improving mobility. We hypothesized that the effects of postoperative cooling and compression after knee arthroscopy would be reflected in changes in the concentrations of metabolic and inflammatory markers in the synovial membrane. Forty otherwise healthy patients who were to undergo knee arthroscopy were included in the study, and half were randomized to receive postoperative cooling and compression. Microdialysis of the synovial membrane was performed postoperatively, and the concentrations of prostaglandin E₂ (PGE₂), glucose, lactate, glycerol, and glutamate as well as the ethanol exchange ratio (which indicates blood flow) were measured. The temperature of the knee was monitored, and postoperative pain was assessed by the patient with use of a visual analog scale, a numeric rating scale, and the need for rescue medication. Application of the cooling and compression device after knee arthroscopy significantly lowered the temperature in the operatively treated knee (as measured on the skin, within the joint capsule, and intra-articularly). The cooling and compression appeared to decrease inflammation, as indicated by a temperature-sensitive decrease in the PGE₂ concentration. The hypothermia also decreased the metabolic rate of the synovial tissue and thus decreased energy requirements, as shown by the stability of the lactate concentration over time despite the decreased blood flow that was indicated by the increasing ethanol exchange ratio. No effect of the compression and cooling on postoperative pain was detected. Local cryotherapy and compression after knee arthroscopy significantly lowered the temperature in the knee postoperatively, and the synovial PGE₂ concentration was correlated with the temperature. Since PGE₂ is a marker of pain and inflammation, the postoperative local cooling and compression appeared to have a positive anti-inflammatory effect.

Brownian motion and thermophoresis effects on Peristaltic slip flow of a MHD nanofluid in a symmetric/asymmetric channel

NASA Astrophysics Data System (ADS)

Sucharitha, G.; Sreenadh, S.; Lakshminarayana, P.; Sushma, K.

2017-11-01

The slip and heat transfer effects on MHD peristaltic transport of a nanofluid in a non-uniform symmetric/asymmetric channel have studied under the assumptions of elongated wave length and negligible Reynolds number. From the simplified governing equations, the closed form solutions for velocity, stream function, temperature and concentrations are obtained. Also dual solutions are discussed for symmetric and asymmetric channel cases. The effects of important physical parameters are explained graphically. The slip parameter decreases the fluid velocity in middle of the channel whereas it increases the velocity at the channel walls. Temperature and concentration are decreasing and increasing functions of radiation parameter respectively. Moreover, velocity, temperature and concentrations are high in symmetric channel when compared with asymmetric channel.

Temperature Effects of Electric Field on the First Excited State of Strong Coupling Polaron in a CsI Quantum Pseudodot

NASA Astrophysics Data System (ADS)

Sun, Yong; Ding, Zhao-Hua; Xiao, Jing-Lin

2017-03-01

Employing variational method of Pekar type (VMPT), this paper investigates the first-excited state energy (FESE), excitation energy and transition frequency of the strongly-coupled polaron in the CsI quantum pseudodot (QPD) with electric field. The temperature effects on the strong-coupling polaron in electric field are calculated by using the quantum statistical theory (QST). The results from the present investigation show that the FESE, excitation energy and transition frequency increase (decrease) firstly and then at lower (higher) temperature regions. They are decreasing functions of the electric field strength. Supported by the National Natural Science Foundation of China under Grant No. 11464033

Far-field brainstem responses evoked by vestibular and auditory stimuli exhibit increases in interpeak latency as brain temperature is decreased

NASA Technical Reports Server (NTRS)

Hoffman, L. F.; Horowitz, J. M.

1984-01-01

The effect of decreasing of brain temperature on the brainstem auditory evoked response (BAER) in rats was investigated. Voltage pulses, applied to a piezoelectric crystal attached to the skull, were used to evoke stimuli in the auditory system by means of bone-conducted vibrations. The responses were recorded at 37 C and 34 C brain temperatures. The peaks of the BAER recorded at 34 C were delayed in comparison with the peaks from the 37 C wave, and the later peaks were more delayed than the earlier peaks. These results indicate that an increase in the interpeak latency occurs as the brain temperature is decreased. Preliminary experiments, in which responses to brief angular acceleration were used to measure the brainstem vestibular evoked response (BVER), have also indicated increases in the interpeak latency in response to the lowering of brain temperature.

Biofeedback-assisted relaxation training to decrease test anxiety in nursing students.

PubMed

Prato, Catherine A; Yucha, Carolyn B

2013-01-01

Nursing students experiencing debilitating test anxiety may be unable to demonstrate their knowledge and have potential for poor academic performance. A biofeedback-assisted relaxation training program was created to reduce test anxiety. Anxiety was measured using Spielberger's Test Anxiety Inventory and monitoring peripheral skin temperature, pulse, and respiration rates during the training. Participants were introduced to diaphragmatic breathing, progressive muscle relaxation, and autogenic training. Statistically significant changes occurred in respiratory rates and skin temperatures during the diaphragmatic breathing session; respiratory rates and peripheral skin temperatures during progressive muscle relaxation session; respiratory and pulse rates, and peripheral skin temperatures during the autogenic sessions. No statistically significant difference was noted between the first and second TAI. Subjective test anxiety scores of the students did not decrease by the end of training. Autogenic training session was most effective in showing a statistically significant change in decreased respiratory and pulse rates and increased peripheral skin temperature.

Temperature and pressure dependent thermodynamic behavior of 2H-CuInO2

NASA Astrophysics Data System (ADS)

Bhamu, K. C.

2018-05-01

Density functional theory and quasi-harmonic Debye model has been used to study the thermodynamic properties of 2H-CuInO2. At the optimized structural parameters, pressure (0 to 80 GPa) dependent variation in the various thermodynamic properties, i.e. unit cell volume (V), bulk modulus (B), specific heat (Cv), Debye temperature (θD), Grüneisen parameter (γ) and thermal expansion coefficient (α) are calculated for various temperature values. The results predict that the pressure has significant effect on unit cell volume and bulk modulus while the temperature shows negligible effect on both parameters. With increasing temperature thermal expansion coefficient increase while with increasing pressure it decreases. The specific heat remains close to zero for ambient pressure and temperature values and it increases with increasing temperature. It is observed that the pressure has high impact on Debye temperature and Grüneisen parameter instead of temperature. Debye temperature and Grüneisen parameter both remains almost constant for the temperature range (0-300K) while Grüneisen parameter decrease with increasing pressure at constant temperature and Debye temperature increases rapidly with increasing pressure. An increase in Debye temperature with respect to pressure shows that the thermal vibration frequency changes rapidly.

Effect of water temperature and population density on the population dynamics of Schistosoma mansoni intermediate host snails.

PubMed

McCreesh, Nicky; Arinaitwe, Moses; Arineitwe, Wilber; Tukahebwa, Edridah M; Booth, Mark

2014-11-12

Mathematical models can be used to identify areas at risk of increased or new schistosomiasis transmission as a result of climate change. The results of these models can be very different when parameterised to different species of host snail, which have varying temperature preferences. Currently, the experimental data needed by these models are available for only a few species of snail. The choice of density-dependent functions can also affect model results, but the effects of increasing densities on Biomphalaria populations have only previously been investigated in artificial aquariums. Laboratory experiments were conducted to estimate Biomphalaria sudanica mortality, fecundity and growth rates at ten different constant water temperatures, ranging from 13-32°C. Snail cages were used to determine the effects of snail densities on B. sudanica and B. stanleyi mortality and fecundity rates in semi-natural conditions in Lake Albert. B. sudanica survival and fecundity were highest at 20°C and 22°C respectively. Growth in shell diameter was estimated to be highest at 23°C in small and medium sized snails, but the relationship between temperature and growth was not clear. The fecundity of both B. sudanica and B. stanleyi decreased by 72-75% with a four-fold increase in population density. Increasing densities four-fold also doubled B. stanleyi mortality rates, but had no effect on the survival of B. sudanica. The optimum temperature for fecundity was lower for B. sudanica than for previously studied species of Biomphalaria. In contrast to other Biomphalaria species, B. sudanica have a distinct peak temperature for survival, as opposed to a plateau of highly suitable temperatures. For both B. stanleyi and B. sudanica, fecundity decreased with increasing population densities. This means that snail populations may experience large fluctuations in numbers, even in the absence of any external factors such as seasonal temperature changes. Survival also decreased with increasing density for B. stanleyi, in contrast to B. sudanica and other studied Biomphalaria species where only fecundity has been shown to decrease.

Influence of temperature on patch residence time in parasitoids: physiological and behavioural mechanisms

NASA Astrophysics Data System (ADS)

Moiroux, Joffrey; Abram, Paul K.; Louâpre, Philippe; Barrette, Maryse; Brodeur, Jacques; Boivin, Guy

2016-04-01

Patch time allocation has received much attention in the context of optimal foraging theory, including the effect of environmental variables. We investigated the direct role of temperature on patch time allocation by parasitoids through physiological and behavioural mechanisms and its indirect role via changes in sex allocation and behavioural defences of the hosts. We compared the influence of foraging temperature on patch residence time between an egg parasitoid, Trichogramma euproctidis, and an aphid parasitoid, Aphidius ervi. The latter attacks hosts that are able to actively defend themselves, and may thus indirectly influence patch time allocation of the parasitoid. Patch residence time decreased with an increase in temperature in both species. The increased activity levels with warming, as evidenced by the increase in walking speed, partially explained these variations, but other mechanisms were involved. In T. euproctidis, the ability to externally discriminate parasitised hosts decreased at low temperature, resulting in a longer patch residence time. Changes in sex allocation with temperature did not explain changes in patch time allocation in this species. For A. ervi, we observed that aphids frequently escaped at intermediate temperature and defended themselves aggressively at high temperature, but displayed few defence mechanisms at low temperature. These defensive behaviours resulted in a decreased patch residence time for the parasitoid and partly explained the fact that A. ervi remained for a shorter time at the intermediate and high temperatures than at the lowest temperature. Our results suggest that global warming may affect host-parasitoid interactions through complex mechanisms including both direct and indirect effects on parasitoid patch time allocation.

Lung function association with outdoor temperature and relative humidity and its interaction with air pollution in the elderly.

PubMed

Lepeule, Johanna; Litonjua, Augusto A; Gasparrini, Antonio; Koutrakis, Petros; Sparrow, David; Vokonas, Pantel S; Schwartz, Joel

2018-04-21

While the effects of weather variability on cardio-respiratory mortality are well described, research examining the effects on morbidity, especially for vulnerable populations, is warranted. We investigated the associations between lung function and outdoor temperature (T in Celsius degrees (°C)) and relative humidity (RH), in a cohort of elderly men, the Normative Aging Study. Our study included 1103 participants whose forced vital capacity (FVC), forced expiratory volume in one second (FEV 1 ), and weather exposures were assessed one to five times during the period 1995-2011 (i.e. 3162 observations). Temperature and relative humidity were measured at one location 4 h to 7 days before lung function tests. We used linear mixed-effects models to examine the associations with outdoor T and RH. A 5-degree increase in the 3-day moving average T was associated with a significant 0.7% decrease (95%CI: -1.24, -0.20) in FVC and a 5% increase in the 7-day moving average RH was associated with a significant 0.2% decrease (95%CI: -0.40, -0.02) in FVC and FEV 1 . The associations with T were greater when combined with higher exposures of black carbon with a 1.6% decrease (95%CI -2.2; -0.9) in FVC and a 1% decrease (95%CI -1.7; -0.4) in FEV 1 . The relationships between T and RH and lung function were linear. No synergistic effect of T and RH was found. Heat and lung function are two predictors of mortality. Our findings suggest that increases in temperature and relative humidity are related to decreases in lung function, and such observations might be amplified by high black carbon levels. Copyright © 2018 Elsevier Inc. All rights reserved.

Minimum daily core body temperature in western grey kangaroos decreases as summer advances: a seasonal pattern, or a direct response to water, heat or energy supply?

PubMed

Maloney, Shane K; Fuller, Andrea; Meyer, Leith C R; Kamerman, Peter R; Mitchell, Graham; Mitchell, Duncan

2011-06-01

Using implanted temperature loggers, we measured core body temperature in nine western grey kangaroos every 5 min for 24 to 98 days in spring and summer. Body temperature was highest at night and decreased rapidly early in the morning, reaching a nadir at 10:00 h, after ambient temperature and solar radiation had begun to increase. On hotter days, the minimum morning body temperature was lower than on cooler days, decreasing from a mean of 36.2°C in the spring to 34.0°C in the summer. This effect correlated better with the time of the year than with proximate thermal stressors, suggesting that either season itself or some factor correlated with season, such as food availability, caused the change. Water saving has been proposed as a selective advantage of heterothermy in other large mammals, but in kangaroos the water savings would have been small and not required in a reserve with permanent standing water. We calculate that the lower core temperature could provide energy savings of nearly 7%. It is likely that the heterothermy that we observed on hot days results either from decreased energy intake during the dry season or from a seasonal pattern entrained in the kangaroos that presumably has been selected for because of decreased energy availability during the dry season.

Effect of a pharmacologically induced decrease in core temperature in rats resuscitated from cardiac arrest

EPA Science Inventory

Targeted temperature management is recommended to reduce brain damage after resuscitation from cardiac arrest in humans although the optimal target temperature remains controversial. 1 4 The American Heart Association (AHA) and the International Liaison Committee on Resuscitation...

Hot under the collar: The impact of heat on game play.

PubMed

Young, Michael E; McCoy, Anthony W; Hutson, John P; Schlabach, Meredith; Eckels, Steven

2017-03-01

High temperatures have been documented to affect behavior in a variety of ways depending on the nature of the task. We extended this prior research by examining the effects of dynamically changing temperature on various aspects of performance in a video game task. In the span of approximately an hour, temperature was gradually increased, stayed constant for a period of time, and gradually decreased to baseline. The gaming task was a variation on one used to assess impulsivity in participants thus allowing the possibility of assessing the effects of temperature on impulsive choice. Rather than heat increasing impulsivity and thus decreasing wait times, participants showed increases in wait times as temperature increased which either suggests that participants were becoming more self-controlled under heat or that the documented negative impact of heat on motor functioning was dominating their performance. Importantly, the participant's sensitivity to the changing task requirements was not affected by changes in temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

Short communication: calf body temperature following chemical disbudding with sedation: effects of milk allowance and supplemental heat.

PubMed

Vasseur, E; Rushen, J; de Passillé, A M

2014-01-01

The use of caustic paste combined with a sedative is one of the least painful methods for disbudding. It is recommended to disbud at as early as 5d of age. However, the sedative xylazine reportedly causes a decrease in core temperature. Furthermore, young calves do not thermoregulate efficiently. We investigated the effects of disbudding calves at 5d of age using caustic paste and xylazine sedation on body temperature, activity, and milk intake of 46 individually housed 5-d-old calves in a 2×2 factorial design, with milk fed at 4.5L/d (low-fed calves) versus 9L/d (high-fed calves), with or without a heat lamp. Body temperature, calf activity (standing time), and barn temperature were monitored continuously using automatic data loggers on the day of, before the day of, and the day after disbudding. All calves were injected intramuscularly with 0.25mL of 2mg/mL xylazine 20min before disbudding (dose: 0.12±0.003mL/kg of BW). We found that the body temperature of 5-d-old calves decreased immediately after the injection of the sedative xylazine. The body temperature of calves decreased 0.9±0.09°C and it took 3.8±0.32h to climb back to the preinjection body temperature. Calves that were fed the lower amount of milk, received a higher dose of xylazine (mL/kg BW), or were disbudded in a colder environment were more affected by body temperature variations (lower and longest decrease in body temperature and higher magnitude). Calf activity recovery followed the pattern of body temperature recovery. Milk allowance and supplemental heat did not help enhance recovery during the 6h following the procedure. The disbudding procedure did not affect milk intake but calves with less body temperature decrease or kept in a warmer environment drank more milk following disbudding. Low-fed calves were overall more affected by the procedure than high-fed calves during the disbudding day and the following day (greater decrease in body temperature and drank less in the colder environment). Providing a high-milk diet is a suitable option to help mitigate calf discomfort due to the disbudding procedure, whereas using a heat lamp does not seem to help, at least in a mildly cold winter. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The effect of temperature changes on electrical performance of the betavoltaic cell.

PubMed

Wang, Guanquan; Hu, Rui; Wei, Hongyuan; Zhang, Huaming; Yang, Yuqing; Xiong, Xiaoling; Liu, Guoping; Luo, Shunzhong

2010-12-01

There is a significant relationship between temperature and electrical performance of a betavoltaic cell. Two silicon diodes used as energy conversion devices of betavoltaic cells were irradiated by Ni-63, and the relationships between the temperature and the electrical performance such as V(oc), I(sc), and P(max) were examined. I(sc) increased very little as temperature increased but V(oc) decreased considerably. The changing values of V(oc) were -3.1 and -3.0 mV/K, respectively, in the temperature range 233.15-333.15 K. As a result of this, P(max) and eta also decreased markedly. Copyright 2010 Elsevier Ltd. All rights reserved.

Effect of pyrolysis temperature and air flow on toxicity of gases from a polycarbonate polymer

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Brick, V. E.; Brauer, D. P.

1978-01-01

A polycarbonate polymer was evaluated for toxicity of pyrolysis gases generated at various temperatures without forced air flow and with 1 L/min air flow, using the toxicity screening test method developed at the University of San Francisco. Time to various animal responses decreased with increasing pyrolysis temperature over the range from 500 C to 800 C. There appeared to be no significant toxic effects at 400 C and lower temperatures.

Influence of Nose Shape and L/D Ratio on Projectile Penetration in Frozen Soil

DTIC Science & Technology

1980-04-01

unexpected when soil properties are considered. Decreasing temperature below -10%C by 100 or 150 has little effect on the constitutive properties of... Effect ....... ............ ............. 10 L/D Influence .......................... .10 Target Temperature Effects ...10. Effect of L/D ratio and mass on flat nose pro- jectile penetration (the solid lines are least square curve fits to the data

The effect of highly activated hopping process on the physical properties of Co-Zn-La ferrite

NASA Astrophysics Data System (ADS)

Ahmed, M. A.; EL-Sayed, M. M.; EL-Desoky, M. M.

2010-01-01

Samples of Co 1-xZn xLa yFe 2-yO 4, 0.1≤ x≤0.9, y=0.25, were prepared using standard ceramic technique. X-ray investigations were carried out in order to assure the formation of the samples in single spinel phase. The dielectric constant ε´ was measured at different temperatures as the function of frequencies ranging from 100 kHz to 3 MHz for the investigated samples. The dielectric constant ε´ increases with temperature up to transition temperature T(ε´) and decreases with frequency. ε´ decreases also with increasing Zn content. Tε´ increases continuously with Zn content depending on frequency. The magnetic susceptibility for the prepared samples was measured using Faraday's method at different temperatures as the function of the magnetic field intensity. The magnetic parameters were calculated from the magnetic susceptibility data, in the temperature range 300-800 K at three different magnetic field intensities of 720, 1070 and 1380 Oe. The data show a decrease in the magnetic susceptibility till it reaches the Curie temperature TC. It is noted that the effective magnetic moment ( μeff.) gives the same trend as that of TC with Zn content.

Observations of the temperature dependent response of ozone to NOx reductions in the Sacramento, CA urban plume

NASA Astrophysics Data System (ADS)

Lafranchi, B. W.; Goldstein, A. H.; Cohen, R. C.

2011-07-01

Observations of NOx in the Sacramento, CA region show that mixing ratios decreased by 30 % between 2001 and 2008. Here we use an observation-based method to quantify net ozone (O3) production rates in the outflow from the Sacramento metropolitan region and examine the O3 decrease resulting from reductions in NOx emissions. This observational method does not rely on assumptions about detailed chemistry of ozone production, rather it is an independent means to verify and test these assumptions. We use an instantaneous steady-state model as well as a detailed 1-D plume model to aid in interpretation of the ozone production inferred from observations. In agreement with the models, the observations show that early in the plume, the NOx dependence for Ox (Ox = O3 + NO2) production is strongly coupled with temperature, suggesting that temperature-dependent biogenic VOC emissions and other temperature-related effects can drive Ox production between NOx-limited and NOx-suppressed regimes. As a result, NOx reductions were found to be most effective at higher temperatures over the 7 year period. We show that violations of the California 1-h O3 standard (90 ppb) in the region have been decreasing linearly with decreases in NOx (at a given temperature) and predict that reductions of NOx concentrations (and presumably emissions) by an additional 30 % (relative to 2007 levels) will eliminate violations of the state 1 h standard in the region. If current trends continue, a 30 % decrease in NOx is expected by 2012, and an end to violations of the 1 h standard in the Sacramento region appears to be imminent.

Unsteady Convection Flow and Heat Transfer over a Vertical Stretching Surface

PubMed Central

Cai, Wenli; Su, Ning; Liu, Xiangdong

2014-01-01

This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient. PMID:25264737

Effects of annealing temperature on structure and magnetic properties of CoAl0.2Fe1.8O4/SiO2 nanocomposites

NASA Astrophysics Data System (ADS)

Wang, L.; Li, J.; Liu, M.; Zhang, Y. M.; Lu, J. B.; Li, H. B.

2012-12-01

CoAl0.2Fe1.8O4/SiO2 nanocomposites were prepared by sol-gel method. The effects of annealing temperature on the structure and magnetic properties of the samples were studied by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer and Mössbauer spectroscopy. The results show that the CoAl0.2Fe1.8O4 in the samples exhibits a spinel structure after being annealed. As annealing temperature increases from 800 to 1200 °C, the average grain size of CoAl0.2Fe1.8O4 in the nanocomposites increases from 5 to 41 nm while the lattice constant decreases from 0.8397 to 0.8391 nm, the saturation magnetization increases from 21.96 to 41.53 emu/g. Coercivity reaches a maximum of 1082 Oe for the sample annealed at 1100 °C, and thereafter decreases with further increasing annealing temperature. Mössbauer spectra show that the isomer shift decreases, hyperfine field increases and the samples transfer from mixed state of superparamagnetic and magnetic order to the completely magnetic order with annealing temperature increasing from 800 to 1200 °C.

Unsteady convection flow and heat transfer over a vertical stretching surface.

PubMed

Cai, Wenli; Su, Ning; Liu, Xiangdong

2014-01-01

This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient.

Sensitivity of surface temperature and atmospheric temperature to perturbations in the stratospheric concentration of ozone and nitrogen dioxide

NASA Technical Reports Server (NTRS)

Ramanathan, V.; Callis, L. B.; Boughner, R. E.

1976-01-01

A radiative-convective model is proposed for estimating the sensitivity of the atmospheric radiative heating rates and atmospheric and surface temperatures to perturbations in the concentration of O3 and NO2 in the stratosphere. Contribution to radiative energy transfer within the atmosphere from H2O, CO2, O3, and NO2 is considered. It is found that the net solar radiation absorbed by the earth-atmosphere system decreases with a reduction in O3; if the reduction of O3 is accompanied by an increase in NO2, there is a compensating effect due to solar absorption by NO2. The surface temperature and atmospheric temperature decrease with decreasing stratospheric O3. Another major conclusion is the strong sensitivity of surface temperature to the vertical distribution of O3 within the atmosphere. The results should be considered as reflecting the sensitivity of the proposed model rather than the sensitivity of the actual earth-atmosphere system.

Effects of tip-substrate gap, deposition temperature, holding time, and pull-off velocity on dip-pen lithography investigated using molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Wu, Cheng-Da; Fang, Te-Hua; Lin, Jen-Fin

2012-05-01

The process parameters in the dip-pen nanolithography process, including tip-substrate gap, deposition temperature, holding time, and pull-off velocity are evaluated in terms of the mechanism of molecular transference, alkanethiol meniscus characteristic, surface adsorbed energy, and pattern formation using molecular dynamics simulations. The simulation results clearly show that the optimum deposition occurs at a smaller tip-substrate gap, a slower pull-off velocity, a higher temperature, and a longer holding time. The pattern area increases with decreasing tip-substrate gap and increasing deposition temperature and holding time. With an increase in deposition temperature, the molecular transfer ability significantly increases. Pattern height is a function of meniscus length. When the pull-off velocity is decreased, the pattern height increases. The height of the neck in meniscus decreases and the neck width increases with holding time. Meniscus size increases with increasing deposition temperature and holding time.

Annealing Effects on the Normal-State Resistive Properties of Underdoped Cuprates

NASA Astrophysics Data System (ADS)

Vovk, R. V.; Khadzhai, G. Ya.; Nazyrov, Z. F.; Kamchatnaya, S. N.; Feher, A.; Dobrovolskiy, O. V.

2018-05-01

The influence of room-temperature annealing on the parameters of the basal-plane electrical resistance of underdoped YBa_2Cu_3O_{7-δ } and HoBa_2Cu_3O_{7-δ } single crystals in the normal and superconducting states is investigated. The form of the derivatives dρ (T)/dT makes it possible to determine the onset temperature of the fluctuation conductivity and indicates a nonuniform distribution of the labile oxygen. Annealing has been revealed to lead to a monotonic decrease in the oxygen deficiency, that primarily manifests itself as a decrease in the residual resistance, an increase of T_c, and a decrease in the Debye temperature.

Canopy storage capacity and wettability of leaves and needles: The effect of water temperature changes

NASA Astrophysics Data System (ADS)

Klamerus-Iwan, Anna; Błońska, Ewa

2018-04-01

The canopy storage capacity (S) is a major component of the surface water balance. We analysed the relationship between the tree canopy water storage capacity and leaf wettability under changing simulated rainfall temperature. We estimated the effect of the rain temperature change on the canopy storage capacity and contact angle of leave and needle surfaces based on two scenarios. Six dominant forest trees were analysed: English oak (Quercus roburL.), common beech (Fagus sylvatica L.), small-leaved lime (Tilia cordata Mill), silver fir (Abies alba), Scots pine (Pinus sylvestris L.),and Norway spruce (Picea abies L.). Twigs of these species were collected from Krynica Zdrój, that is, the Experimental Forestry unit of the University of Agriculture in Cracow (southern Poland). Experimental analyses (simulations of precipitation) were performed in a laboratory under controlled conditions. The canopy storage capacity and leaf wettability classification were determined at 12 water temperatures and a practical calculator to compute changes of S and contact angles of droplets was developed. Among all species, an increase of the rainfall temperature by 0.7 °C decreases the contact angle between leave and needle surfaces by 2.41° and increases the canopy storage capacity by 0.74 g g-1; an increase of the rain temperature by 2.7 °C decreases the contact angle by 9.29° and increases the canopy storage capacity by 2.85 g g-1. A decreased contact angle between a water droplet and leaf surface indicates increased wettability. Thus, our results show that an increased temperature increases the leaf wettability in all examined species. The comparison of different species implies that the water temperature has the strongest effect on spruce and the weakest effect on oak. These data indicate that the rainfall temperature influences the canopy storage capacity.

Confinement effects on glass transition temperature, transition breadth, and expansivity: comparison of ellipsometry and fluorescence measurements on polystyrene films.

PubMed

Kim, S; Hewlett, S A; Roth, C B; Torkelson, J M

2009-09-01

Using ellipsometry, we characterized the nanoconfinement effect on the glass transition temperature (T (g)of supported polystyrene (PS) films employing two methods: the intersection of fits to the temperature (Tdependences of rubbery- and glassy-state thicknesses, and the transition mid-point between rubbery- and glassy-state expansivities. The results demonstrate a strong effect of thickness: T(g) (bulk) - T(g)(23 nm) = 10 degrees C. The T -range needed for accurate measurement increases significantly with decreasing thickness, an effect that arises from the broadening of the transition with confinement and a region below T (g) where expansivity slowly decreases with decreasing T . As determined from expansivities, the T (g) breadth triples in going from bulk films to a 21-nm-thick film; this broadening of the transition may be a more dramatic effect of confinement than the T (g) reduction itself. In contrast, there is little effect of confinement on the rubbery- and glassy-state expansivities. Compared with ellipsometry, T (g) 's from fluorescence agree well in bulk films but yield lower values in nanoconfined films: T (g)(bulk) - T (g)(23 nm) = 15( degrees ) C via fluorescence. This small difference in the T (g) confinement effect reflects differences in how fluorescence and ellipsometry report "average T (g) " with confinement. With decreasing nanoscale thickness, fluorescence may slightly overweight the contribution of the free-surface layer while ellipsometry may evenly weight or underweight its contribution.

Confinement effects on glass transition temperature, transition breadth, and expansivity: Comparison of ellipsometry and fluorescence measurements on polystyrene films

NASA Astrophysics Data System (ADS)

Kim, S.; Hewlett, S. A.; Roth, C. B.; Torkelson, J. M.

2009-09-01

Using ellipsometry, we characterized the nanoconfinement effect on the glass transition temperature (T gof supported polystyrene (PS) films employing two methods: the intersection of fits to the temperature (Tdependences of rubbery- and glassy-state thicknesses, and the transition mid-point between rubbery- and glassy-state expansivities. The results demonstrate a strong effect of thickness: ensuremath Tg(bulk)-Tg(23{ nm})= 10 circ C. The T -range needed for accurate measurement increases significantly with decreasing thickness, an effect that arises from the broadening of the transition with confinement and a region below T g where expansivity slowly decreases with decreasing T . As determined from expansivities, the T g breadth triples in going from bulk films to a 21-nm-thick film; this broadening of the transition may be a more dramatic effect of confinement than the T g reduction itself. In contrast, there is little effect of confinement on the rubbery- and glassy-state expansivities. Compared with ellipsometry, T g ’s from fluorescence agree well in bulk films but yield lower values in nanoconfined films: T g(bulk) - T g(23 nm) = 15° C via fluorescence. This small difference in the T g confinement effect reflects differences in how fluorescence and ellipsometry report “average T g ” with confinement. With decreasing nanoscale thickness, fluorescence may slightly overweight the contribution of the free-surface layer while ellipsometry may evenly weight or underweight its contribution. in here

3D-modelling of the thermal circumstances of a lake under artificial aeration

NASA Astrophysics Data System (ADS)

Tian, Xiaoqing; Pan, Huachen; Köngäs, Petrina; Horppila, Jukka

2017-12-01

A 3D-model was developed to study the effects of hypolimnetic aeration on the temperature profile of a thermally stratified Lake Vesijärvi (southern Finland). Aeration was conducted by pumping epilimnetic water through the thermocline to the hypolimnion without breaking the thermal stratification. The model used time transient equation based on Navier-Stokes equation. The model was fitted to the vertical temperature distribution and environmental parameters (wind, air temperature, and solar radiation) before the onset of aeration, and the model was used to predict the vertical temperature distribution 3 and 15 days after the onset of aeration (1 August and 22 August). The difference between the modelled and observed temperature was on average 0.6 °C. The average percentage model error was 4.0% on 1 August and 3.7% on 22 August. In the epilimnion, model accuracy depended on the difference between the observed temperature and boundary conditions. In the hypolimnion, the model residual decreased with increasing depth. On 1 August, the model predicted a homogenous temperature profile in the hypolimnion, while the observed temperature decreased moderately from the thermocline to the bottom. This was because the effect of sediment was not included in the model. On 22 August, the modelled and observed temperatures near the bottom were identical demonstrating that the heat transfer by the aerator masked the effect of sediment and that exclusion of sediment heat from the model does not cause considerable error unless very short-term effects of aeration are studied. In all, the model successfully described the effects of the aerator on the lake's temperature profile. The results confirmed the validity of the applied computational fluid dynamic in artificial aeration; based on the simulated results, the effect of aeration can be predicted.

Effects of a neonicotinoid pesticide on thermoregulation of African honey bees (Apis mellifera scutellata).

PubMed

Tosi, Simone; Démares, Fabien J; Nicolson, Susan W; Medrzycki, Piotr; Pirk, Christian W W; Human, Hannelie

Thiamethoxam is a widely used neonicotinoid pesticide that, as agonist of the nicotinic acetylcholine receptors, has been shown to elicit a variety of sublethal effects in honey bees. However, information concerning neonicotinoid effects on honey bee thermoregulation is lacking. Thermoregulation is an essential ability for the honey bee that guarantees the success of foraging and many in-hive tasks, especially brood rearing. We tested the effects of acute exposure to thiamethoxam (0.2, 1, 2ng/bee) on the thorax temperatures of foragers exposed to low (22°C) and high (33°C) temperature environments. Thiamethoxam significantly altered honey bee thorax temperature at all doses tested; the effects elicited varied depending on the environmental temperature and pesticide dose to which individuals were exposed. When bees were exposed to the high temperature environment, the high dose of thiamethoxam increased their thorax temperature 1-2h after exposure. When bees were exposed to the low temperature, the higher doses of the neonicotinoid reduced bee thorax temperatures 60-90min after treatment. In both experiments, the neonicotinoid decreased the temperature of bees the day following the exposure. After a cold shock (5min at 4°C), the two higher doses elicited a decrease of the thorax temperature, while the lower dose caused an increase, compared to the control. These alterations in thermoregulation caused by thiamethoxam may affect bee foraging activity and a variety of in-hive tasks, likely leading to negative consequences at the colony level. Our results shed light on sublethal effect of pesticides which our bees have to deal with. Copyright © 2016 Elsevier Ltd. All rights reserved.

The association between ambient temperature and children's lung function in Baotou, China

NASA Astrophysics Data System (ADS)

Li, Shanshan; Guo, Yuming; Williams, Gail; Baker, Peter; Ye, Xiaofang; Madaniyazi, Lina; Kim, Dae-Seon; Pan, Xiaochuan

2015-07-01

The objective of this study is to examine the association between ambient temperature and children's lung function in Baotou, China. We recruited 315 children (8-12 years) from Baotou, China in the spring of 2004, 2005, and 2006. They performed three successive forced expiratory measurements three times daily (morning, noon, and evening) for about 5 weeks. The highest peak expiratory flow (PEF) was recorded for each session. Daily data on ambient temperature, relative humidity, and air pollution were monitored during the same period. Mixed models with a distributed lag structure were used to examine the effects of temperature on lung function while adjusting for individual characteristics and environmental factors. Low temperatures were significantly associated with decreases in PEF. The effects lasted for lag 0-2 days. For all participants, the cumulative effect estimates (lag 0-2 days) were -1.44 (-1.93, -0.94) L/min, -1.39 (-1.92, -0.86) L/min, -1.40 (-1.97, -0.82) L/min, and -1.28 (-1.69, -0.88) L/min for morning, noon, evening, and daily mean PEF, respectively, associated with 1 °C decrease in daily mean temperature. Generally, the effects of temperature were slightly stronger in boys than in girls for noon, evening, and daily mean PEF, while the effects were stronger in girls for morning PEF. PM2.5 had joint effects with temperature on children's PEF. Higher PM2.5 increased the impacts of low temperature. Low ambient temperatures are associated with lower lung function in children in Baotou, China. Preventive health policies will be required for protecting children from the cold weather.

A novel method for computing effective diffusivity: Application to helium implanted α-Fe thin films

NASA Astrophysics Data System (ADS)

Dunn, Aaron; Agudo-Merida, Laura; Martin-Bragado, Ignacio; McPhie, Mathieu; Cherkaoui, Mohammed; Capolungo, Laurent

2014-05-01

The effective diffusivity of helium in thin iron films is quantified using spatially resolved stochastic cluster dynamics and object kinetic Monte Carlo simulations. The roles of total displacement dose (in DPA), damage rate, helium to DPA ratio, layer thickness, and damage type (cascade damage vs Frenkel pair implantation) on effective He diffusivity are investigated. Helium diffusivity is found to decrease with increasing total damage and decreasing damage rate. Arrhenius plots show strongly increased helium diffusivity at high temperatures, high total implantation, and low implantation rates due to decreased vacancy and vacancy cluster concentrations. At low temperatures, effective diffusivity is weakly dependent on foil thickness while at high temperatures, narrower foils prevent defect accumulation by releasing all defects at the free surfaces. Helium to DPA ratio is not shown to strongly change helium diffusivity in the range of irradiation conditions simulated. Frenkel pair implantation is shown to cause higher effective diffusivity and more complex diffusion mechanisms than cascade implantation. The results of these simulations indicate that the differences in damage rates between implantation experiments and fission or fusion environments may result in differences in the final microstructure.

Microplastics have a more profound impact than elevated temperatures on the predatory performance, digestion and energy metabolism of an Amazonian cichlid.

PubMed

Wen, Bin; Zhang, Nan; Jin, Shi-Rong; Chen, Zai-Zhong; Gao, Jian-Zhong; Liu, Ying; Liu, Han-Peng; Xu, Zhe

2018-02-01

Knowledge on the impacts of microplastics (MPs) pollution on freshwater environments and biota remains limited. Meanwhile, freshwater ecosystems have been threatened by elevated temperatures caused by climate change. To date, no information exists on how MPs-especially under elevated temperature conditions-affect predatory performance, digestive processes and metabolic pathways in freshwater organisms. Here, we examined MPs, elevated temperature and their combined effects on juveniles (0+ group) of an Amazonian cichlid, the discus fish (Symphysodon aequifasciatus). For 30 days, fish were exposed to ambient or elevated temperatures (i.e., 28 or 31 °C) in the absence or presence of MPs (i.e., 0 or 200 μg/L). The following metrics were quantified: MPs accumulation; predatory performance; and biomarkers involved in neurotransmission, digestion and energy production. The results showed that survival rate and body length were not affected by MPs, elevated temperatures or their combination. Elevated temperatures resulted in an increase in MP concentrations in fish bodies. Exposure to MPs decreased the post-exposure predatory performance (PEPP) at ambient temperatures but not at elevated temperatures. Elevated temperatures, however, had no effect on the PEPP but antagonistically interacted with MPs, leading to similar predatory performances under present and future conditions. Acetylcholinesterase (AChE) activity was only affected by MPs and decreased in the presence of MPs, indicating adverse effects in nervous and neuromuscular function and, thus, potentially in predatory performance. Trypsin activity was only influenced by MPs and decreased during exposure to MPs. Elevated temperatures or MPs alone increased the amylase activity but interacted antagonistically. Lipase activity was not influenced by either of the two stressors. In contrast, alkaline phosphatase (ALP) activity was affected by MPs or elevated temperatures alone and decreased with both stressors. Such results indicate deficits in the digestive capabilities of early-stage S. aequifasciatus under elevated temperature conditions and especially during exposure to MPs. Electron transport system (ETS) activity was not influenced by either of the two stressors. Both elevated temperatures and MPs alone increased LDH activity; however, the interaction between the two stressors cancelled activity but was still higher than activity in present conditions. Citrate synthase (CS) activity decreased with elevated temperature but increased during exposure to MPs. Cytochrome c oxidase (COX) activity was only influenced by MPs and increased in the presence of MPs. Thus, S. aequifasciatus juveniles exposed to elevated temperatures and MPs not only relied on anaerobic glycolysis for energy production but also depended on aerobic metabolism in the presence of MPs. Overall, these findings suggested that MPs showed a greater impact than elevated temperatures on the predatory performance, digestion and energy production of S. aequifasciatus. Nevertheless, juvenile survival and growth were minimally impacted, and thus, S. aequifasciatus could cope with near-future temperature increases and MP exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of ocean warming and acidification on fertilization in the Antarctic echinoid Sterechinus neumayeri across a range of sperm concentrations.

PubMed

Ho, M A; Price, C; King, C K; Virtue, P; Byrne, M

2013-09-01

The gametes of marine invertebrates are being spawned into an ocean that is simultaneously warming and decreasing in pH. Predicting the potential for interactive effects of these stressors on fertilization is difficult, especially for stenothermal polar invertebrates adapted to fertilization in cold, viscous water and, when decreased sperm availability may be an additional stressor. The impact of increased temperature (2-4 °C above ambient) and decreased pH (0.2-0.4 pH units below ambient) on fertilization in the Antarctic echinoid Sterechinus neumayeri across a range of sperm concentrations was investigated in cross-factorial experiments in context with near future ocean change projections. The high temperature treatment (+4 °C) was also used to assess thermal tolerance. Gametes from multiple males and females in replicate experiments were used to reflect the multiple spawner scenario in nature. For fertilization at low sperm density we tested three hypotheses, 1) increased temperature enhances fertilization success, 2) low pH reduces fertilization and, 3) due to the cold stenothermal physiology of S. neumayeri, temperature would be the more significant stressor. Temperature and sperm levels had a significant effect on fertilization, but decreased pH did not affect fertilization. Warming enhanced fertilization at the lowest sperm concentration tested likely through stimulation of sperm motility and reduced water viscosity. Our results indicate that fertilization in S. neumayeri, even at low sperm levels potentially found in nature, is resilient to near-future ocean warming and acidification. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of cold compress application on tissue temperature in healthy dogs.

PubMed

Millard, Ralph P; Towle-Millard, Heather A; Rankin, David C; Roush, James K

2013-03-01

To measure the effect of cold compress application on tissue temperature in healthy dogs. 10 healthy mixed-breed dogs. Dogs were sedated with hydromorphone (0.1 mg/kg, IV) and diazepam (0.25 mg/kg, IV). Three 24-gauge thermocouple needles were inserted to a depth of 0.5 (superficial), 1.0 (middle), and 1.5 (deep) cm into a shaved, lumbar, epaxial region to measure tissue temperature. Cold (-16.8°C) compresses were applied with gravity dependence for periods of 5, 10, and 20 minutes. Tissue temperature was recorded before compress application and at intervals for up to 80 minutes after application. Control data were collected while dogs received identical sedation but with no cold compress. Mean temperature associated with 5 minutes of application at the superficial depth was significantly decreased, compared with control temperatures. Application for 10 and 20 minutes significantly reduced the temperature at all depths, compared with controls and 5 minutes of application. Twenty minutes of application significantly decreased temperature at only the middle depth, compared with 10 minutes of application. With this method of cold treatment, increasing application time from 10 to 20 minutes caused a further significant temperature change at only the middle tissue depth; however, for maximal cooling, the minimum time of application should be 20 minutes. Possible changes in tissue temperature and adverse effects of application > 20 minutes require further evaluation.

Effect of test temperature and strain rate on the tensile properties of high-strength, high-conductivity copper alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinkle, S.J.; Eatherly, W.S.

1997-04-01

The unirradiated tensile properties of wrought GlidCop AL25 (ITER grade zero, IGO) solutionized and aged CuCrZr, and cold-worked and aged and solutionized and aged Hycon 3HP{trademark} CuNiBe have been measured over the temperature range of 20-500{degrees}C at strain rates between 4 x 10{sup {minus}4} s{sup {minus}1} and 0.06 s{sup {minus}1}. The measured room temperature electrical conductivity ranged from 64 to 90% IACS for the different alloys. All of the alloys were relatively insensitive to strain rate at room temperature, but the strain rate sensitivity of GlidCop Al25 increased significantly with increasing temperature. The CuNiBe alloys exhibited the best combination ofmore » high strength and high conductivity at room temperature. The strength of CuNiBe decreased slowly with increasing temperature. However, the ductility of CuNiBe decreased rapidly with increasing temperature due to localized deformation near grain boundaries, making these alloy heats unsuitable for typical structural applications above 300{degrees}C. The strength and uniform elongation of GlidCop Al25 decreased significantly with increasing temperature at a strain rate of 1 x 10{sup {minus}3} s{sup {minus}1}, whereas the total elongation was independent of test temperature. The strength and ductility of CuCrZr decreased slowly with increasing temperature.« less

Associations between air temperature and cardio-respiratory mortality in the urban area of Beijing, China: a time-series analysis.

PubMed

Liu, Liqun; Breitner, Susanne; Pan, Xiaochuan; Franck, Ulrich; Leitte, Arne Marian; Wiedensohler, Alfred; von Klot, Stephanie; Wichmann, H-Erich; Peters, Annette; Schneider, Alexandra

2011-05-25

Associations between air temperature and mortality have been consistently observed in Europe and the United States; however, there is a lack of studies for Asian countries. Our study investigated the association between air temperature and cardio-respiratory mortality in the urban area of Beijing, China. Death counts for cardiovascular and respiratory diseases for adult residents (≥15 years), meteorological parameters and concentrations of particulate air pollution were obtained from January 2003 to August 2005. The effects of two-day and 15-day average temperatures were estimated by Poisson regression models, controlling for time trend, relative humidity and other confounders if necessary. Effects were explored for warm (April to September) and cold periods (October to March) separately. The lagged effects of daily temperature were investigated by polynomial distributed lag (PDL) models. We observed a J-shaped exposure-response function only for 15-day average temperature and respiratory mortality in the warm period, with 21.3°C as the threshold temperature. All other exposure-response functions could be considered as linear. In the warm period, a 5°C increase of two-day average temperature was associated with a RR of 1.098 (95% confidence interval (95%CI): 1.057-1.140) for cardiovascular and 1.134 (95%CI: 1.050-1.224) for respiratory mortality; a 5°C decrease of 15-day average temperature was associated with a RR of 1.040 (95%CI: 0.990-1.093) for cardiovascular mortality. In the cold period, a 5°C increase of two-day average temperature was associated with a RR of 1.149 (95%CI: 1.078-1.224) for respiratory mortality; a 5°C decrease of 15-day average temperature was associated with a RR of 1.057 (95%CI: 1.022-1.094) for cardiovascular mortality. The effects remained robust after considering particles as additional confounders. Both increases and decreases in air temperature are associated with an increased risk of cardiovascular mortality. The effects of heat were immediate while the ones of cold became predominant with longer time lags. Increases in air temperature are also associated with an immediate increased risk of respiratory mortality.

Associations between air temperature and cardio-respiratory mortality in the urban area of Beijing, China: a time-series analysis

PubMed Central

2011-01-01

Background Associations between air temperature and mortality have been consistently observed in Europe and the United States; however, there is a lack of studies for Asian countries. Our study investigated the association between air temperature and cardio-respiratory mortality in the urban area of Beijing, China. Methods Death counts for cardiovascular and respiratory diseases for adult residents (≥15 years), meteorological parameters and concentrations of particulate air pollution were obtained from January 2003 to August 2005. The effects of two-day and 15-day average temperatures were estimated by Poisson regression models, controlling for time trend, relative humidity and other confounders if necessary. Effects were explored for warm (April to September) and cold periods (October to March) separately. The lagged effects of daily temperature were investigated by polynomial distributed lag (PDL) models. Results We observed a J-shaped exposure-response function only for 15-day average temperature and respiratory mortality in the warm period, with 21.3°C as the threshold temperature. All other exposure-response functions could be considered as linear. In the warm period, a 5°C increase of two-day average temperature was associated with a RR of 1.098 (95% confidence interval (95%CI): 1.057-1.140) for cardiovascular and 1.134 (95%CI: 1.050-1.224) for respiratory mortality; a 5°C decrease of 15-day average temperature was associated with a RR of 1.040 (95%CI: 0.990-1.093) for cardiovascular mortality. In the cold period, a 5°C increase of two-day average temperature was associated with a RR of 1.149 (95%CI: 1.078-1.224) for respiratory mortality; a 5°C decrease of 15-day average temperature was associated with a RR of 1.057 (95%CI: 1.022-1.094) for cardiovascular mortality. The effects remained robust after considering particles as additional confounders. Conclusions Both increases and decreases in air temperature are associated with an increased risk of cardiovascular mortality. The effects of heat were immediate while the ones of cold became predominant with longer time lags. Increases in air temperature are also associated with an immediate increased risk of respiratory mortality. PMID:21612647

Decrease of body temperature after aglepristone treatment in bitches.

PubMed

Corrada, Y; García, P; de la Sota, P E; Huzman, M; Landoni, M F; Gobello, C

2005-07-01

Body temperature responses and the timing of abortions were evaluated in pregnant bitches with the anti-progestin aglepristone. Fifteen purebred and crossbred, 25-45 days pregnant, were included in this study and seven untreated bitches at the same stage of pregnancy served as controls. Treated bitches were administered two applications of aglepristone (10 mg/kg SC) 24 h apart for pregnancy termination. Pregnancy termination was confirmed by ultrasonographic assessment. Body temperature was rectally measured three times a day for 6 days beginning 24 h before treatment or pregnancy diagnosis in the treated and control bitches, respectively. Additionally, serum progesterone concentrations were assessed at time points during the study in the treated bitches. Pregnancy was terminated in 14 treated bitches in a mean+/-S.E.M. of 4.3+/-0.7 days after treatment. Control bitches remained pregnant. In the treated bitches, but not in the controls, body temperature significantly decreased 24 h after the beginning of the treatments (P < 0.01) and then gradually returned to pre-treatment values. Correlation between the day of mean minimum body temperature and the day of pregnancy termination was low (0.07; > 0.05). Progesterone did not show significant change throughout the study. Body temperature does not seem to be a suitable variable to clinically monitor the aborting effect of aglepristone. Decrease of body temperature after aglepristone treatment could represent further evidence of its hypothalamic effects.

Effects of Pouring Temperature and Electromagnetic Stirring on Porosity and Mechanical Properties of A357 Aluminum Alloy Rheo-Diecasting

NASA Astrophysics Data System (ADS)

Guo, An; Zhao, Junwen; Xu, Chao; Li, Hu; Han, Jing; Zhang, Xu

2018-05-01

Semisolid slurry of A357 aluminum alloy was prepared using a temperature-controllable electromagnetic stirrer and rheo-diecast at different temperatures. The effects of pouring temperature and electromagnetic stirring (EMS) on the porosity in rheo-diecast samples, as well as the relation between porosity and mechanical properties, were investigated. The results show that pouring temperature and EMS had minor influences on rheo-diecast microstructure but marked influence on the porosity. With decreasing slurry pouring temperature, the porosity decreased first and then increased, whereas the maximum pore ratio (ratio of shape factor to diameter of the largest pore) increased first and then decreased. The maximum pore ratio determines the level of tensile strength and elongation, and higher mechanical properties can be obtained with smaller and rounder pores in samples. The mechanical properties of the rheo-diecast samples increased linearly with increasing maximum pore ratio. The maximum pore ratio was 1.43 µm-1, and the minimum porosity level was 0.37% under EMS condition for the rheo-diecast samples obtained at a pouring temperature of 608 °C. With this porosity condition, the maximum tensile strength and elongation were achieved at 274 MPa and 4.9%, respectively. It was also revealed that EMS improves mechanical properties by reduction in porosity and an increase in maximum pore ratio.

Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of soybean (Glycine max) at elevated [CO₂] and temperatures under fully open air field conditions.

PubMed

Rosenthal, David M; Ruiz-Vera, Ursula M; Siebers, Matthew H; Gray, Sharon B; Bernacchi, Carl J; Ort, Donald R

2014-09-01

The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on (1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the maximum carboxylation capacity of Rubisco (Vc,max) and the maximum potential linear electron flux through photosystem II (Jmax), (2) the associated responses of leaf structural and chemical properties related to A, as well as (3) the stomatal limitation (l) imposed on A, for soybean over two growing seasons in a conventionally managed agricultural field in Illinois, USA. Acclimation to elevated [CO2] was consistent over two growing seasons with respect to Vc,max and Jmax. However, elevated temperature significantly decreased Jmax contributing to lower photosynthetic stimulation by elevated CO2. Large seasonal differences in precipitation altered soil moisture availability modulating the complex effects of elevated temperature and CO2 on biochemical and structural properties related to A. Elevated temperature also reduced the benefit of elevated [CO2] by eliminating decreases in stomatal limitation at elevated [CO2]. These results highlight the critical importance of considering multiple environmental factors (i.e. temperature, moisture, [CO2]) when trying to predict plant productivity in the context of climate change. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Pleiotropic effects of temperature-regulated 2-OH-lauroytransferase (PA0011) on Pseudomonas aeruginosa antibiotic resistance, virulence and type III secretion system.

PubMed

Wang, Bobo; Li, Bo; Liang, Ying; Li, Jing; Gao, Lang; Chen, Lin; Duan, Kangmin; Shen, Lixin

2016-02-01

Pseudomonas aeruginosa is an important human pathogen which adapts to changing environment, such as temperature variations and entering host by regulating their gene expression. Here, we report that gene PA0011 in P. aeruginosa PAO1, which encodes a 2-OH-lauroytransferase participating in lipid A biosynthesis, is involved in carbapenem resistance and virulence in a temperature-regulated manner in PAO1. The expression of PA0011 was higher at an environment temperature (21 °C) than that at a body temperature (37 °C). The inactivation of PA0011 rendered increased antibiotic susceptibility and decreased virulence both in vivo and in vitro. The impaired integrity and the decreased stability of the outer membrane were the cause of the increased susceptibility of PAO1(Δ0011) to carbapenem and many other common antibiotics. The reduced endotoxic activity of lipopolysaccharide (LPS) contributed to the decreased virulence both at 21 °C and 37 °C in PAO1 (Δ0011). In addition, we have found that PA0011 repressed the expression of TTSS virulence factors both at transcriptional and translational levels, similar to the effect of O antigen of LPS but unlike any effect of its homologue reported in other bacteria. The effect of PA0011 on resistance to many antibiotics including carbapenem and virulence in P. aeruginosa makes it a target for novel antimicrobial therapies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Process Parameters on Catalytic Incineration of Solvent Emissions

PubMed Central

Ojala, Satu; Lassi, Ulla; Perämäki, Paavo; Keiski, Riitta L.

2008-01-01

Catalytic oxidation is a feasible and affordable technology for solvent emission abatement. However, finding optimal operation conditions is important, since they are strongly dependent on the application area of VOC incineration. This paper presents the results of the laboratory experiments concerning four most central parameters, that is, effects of concentration, gas hourly space velocity (GHSV), temperature, and moisture on the oxidation of n-butyl acetate. Both fresh and industrially aged commercial Pt/Al2O3 catalysts were tested to determine optimal process conditions and the significance order and level of selected parameters. The effects of these parameters were evaluated by computer-aided statistical experimental design. According to the results, GHSV was the most dominant parameter in the oxidation of n-butyl acetate. Decreasing GHSV and increasing temperature increased the conversion of n-butyl acetate. The interaction effect of GHSV and temperature was more significant than the effect of concentration. Both of these affected the reaction by increasing the conversion of n-butyl acetate. Moisture had only a minor decreasing effect on the conversion, but it also decreased slightly the formation of by products. Ageing did not change the significance order of the above-mentioned parameters, however, the effects of individual parameters increased slightly as a function of ageing. PMID:18584032

Temporal changes in climatic variables and their impact on crop yields in southwestern China

NASA Astrophysics Data System (ADS)

Liu, Hong-Bin; Gou, Yu; Wang, Hong-Ye; Li, Hong-Mei; Wu, Wei

2014-08-01

Knowledge of variability in climatic variables changes and its impact on crop yields is important for farmers and policy makers, especially in southwestern China where rainfed agriculture is dominant. In the current study, six climatic parameters (mean temperature, rainfall, relative humidity, sunshine hours, temperature difference, and rainy days) and aggregated yields of three main crops (rice: Oryza sativa L., oilseed rape: Brassica napus L., and tobacco: Nicotiana tabacum L.) during 1985-2010 were collected and analyzed for Chongqing—a large agricultural municipality of China. Climatic variables changes were detected by Mann-Kendall test. Increased mean temperature and temperature difference and decreased relative humidity were found in annual and oilseed rape growth time series ( P < 0.05). Increased sunshine hours were observed during the oilseed rape growth period ( P < 0.05). Rainy days decreased slightly in annual and oilseed rape growth time series ( P < 0.10). Correlation analysis showed that yields of all three crops could benefit from changes in climatic variables in this region. Yield of rice increased with rainfall ( P < 0.10). Yield of oilseed rape increased with mean temperature and temperature difference but decreased with relative humidity ( P < 0.01). Tobacco yield increased with mean temperature ( P < 0.05). Path analysis provided additional information about the importance and contribution paths of climatic variables to crop yields. Temperature difference and sunshine hours had higher direct and indirect effects via other climatic variables on yields of rice and tobacco. Mean temperature, relative humidity, rainy days, and temperature difference had higher direct and indirect effects via others on yield of oilseed rape.

Temporal changes in climatic variables and their impact on crop yields in southwestern China.

PubMed

Liu, Hong-Bin; Gou, Yu; Wang, Hong-Ye; Li, Hong-Mei; Wu, Wei

2014-08-01

Knowledge of variability in climatic variables changes and its impact on crop yields is important for farmers and policy makers, especially in southwestern China where rainfed agriculture is dominant. In the current study, six climatic parameters (mean temperature, rainfall, relative humidity, sunshine hours, temperature difference, and rainy days) and aggregated yields of three main crops (rice: Oryza sativa L., oilseed rape: Brassica napus L., and tobacco: Nicotiana tabacum L.) during 1985-2010 were collected and analyzed for Chongqing-a large agricultural municipality of China. Climatic variables changes were detected by Mann-Kendall test. Increased mean temperature and temperature difference and decreased relative humidity were found in annual and oilseed rape growth time series (P<0.05). Increased sunshine hours were observed during the oilseed rape growth period (P<0.05). Rainy days decreased slightly in annual and oilseed rape growth time series (P<0.10). Correlation analysis showed that yields of all three crops could benefit from changes in climatic variables in this region. Yield of rice increased with rainfall (P<0.10). Yield of oilseed rape increased with mean temperature and temperature difference but decreased with relative humidity (P<0.01). Tobacco yield increased with mean temperature (P<0.05). Path analysis provided additional information about the importance and contribution paths of climatic variables to crop yields. Temperature difference and sunshine hours had higher direct and indirect effects via other climatic variables on yields of rice and tobacco. Mean temperature, relative humidity, rainy days, and temperature difference had higher direct and indirect effects via others on yield of oilseed rape.

Effect of temperature on removal of trace organic chemicals in managed aquifer recharge systems.

PubMed

Alidina, Mazahirali; Shewchuk, Justin; Drewes, Jörg E

2015-03-01

This study was undertaken to investigate whether changes in temperature experienced in MAR systems affect attenuation of trace organic chemicals (TOrCs). A set of laboratory-scale soil columns were placed in a temperature-controlled environmental chamber and operated at five different temperature set-points (30, 20, 10, 8 and 4°C) covering the range of typical groundwater temperatures in cold, moderate and arid climate regions. Removal of bulk organic carbon both in the infiltration zone as well as during deeper infiltration was independent of temperature. Of the 22 TOrCs investigated, only six chemicals exhibited changes in attenuation as a function of temperature. Attenuation of four of the compounds (diclofenac, gemfibrozil, ketoprofen and naproxen) decreased as the temperature was reduced from 30°C to 4°C, likely due to decreased microbial activity at lower temperatures. As the temperature was decreased, however, attenuation of oxybenzone and trimethoprim were noted to increase. This increased attenuation was likely due to more efficient sorption at lower temperatures, though possible changes in the microbial composition as the temperature decreased may also have contributed to this change. Changes in rate constants of attenuation (ka) for the biotransformed TOrCs with temperature suggested the existence of a critical temperature at 10°C for three of the four TOrCs, where significant changes to rates of attenuation occurred. Results from this study indicated that for most TOrCs, changes in temperature do not impact their attenuation. Thus, seasonal changes in temperature are not considered to be a major concern for attenuation of most TOrCs in MAR systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interaction Effects of Temperature and Ozone on Lung Function and Markers of Systemic Inflammation, Coagulation, and Fibrinolysis: A Crossover Study of Healthy Young Volunteers

PubMed Central

Kahle, Juliette J.; Neas, Lucas M.; Devlin, Robert B.; Case, Martin W.; Schmitt, Michael T.; Madden, Michael C.

2014-01-01

Background: Trends in climate suggest that extreme weather events such as heat waves will become more common. High levels of the gaseous pollutant ozone are associated with elevated temperatures. Ozone has been associated with respiratory diseases as well as cardiovascular morbidity and mortality and can reduce lung function and alter systemic markers of fibrinolysis. The interaction between ozone and temperature is unclear. Methods: Sixteen healthy volunteers were exposed in a randomized crossover study to 0.3 ppm ozone and clean air for 2 hr at moderate (22°C) temperature and again at an elevated temperature (32.5°C). In each case lung function was performed and blood taken before and immediately after exposure and the next morning. Results: Ozone exposure at 22°C resulted in a decrease in markers of fibrinolysis the next day. There was a 51.8% net decrease in PAI-1 (plasminogen activator inhibitor-1), a 12.1% net decrease in plasminogen, and a 17.8% net increase in D-dimer. These significantly differed from the response at 32.5°C, where there was a 44.9% (p = 0.002) and a 27.9% (p = 0.001) increase in PAI-1 and plasminogen, respectively, and a 12.5% (p = 0.042) decrease in D-dimer. In contrast, decrements in lung function following ozone exposure were comparable at both moderate and elevated temperatures (forced expiratory volume in 1 sec, –12.4% vs. –7.5%, p > 0.05). No changes in systemic markers of inflammation were observed for either temperature. Conclusion: Ozone-induced systemic but not respiratory effects varied according to temperature. Our study suggests that at moderate temperature ozone may activate the fibrinolytic pathway, while at elevated temperature ozone may impair it. These findings provide a biological basis for the interaction between temperature and ozone on mortality observed in some epidemiologic studies. Citation: Kahle JJ, Neas LM, Devlin RB, Case MW, Schmitt MT, Madden MC, Diaz-Sanchez D. 2015. Interaction effects of temperature and ozone on lung function and markers of systemic inflammation, coagulation, and fibrinolysis: a crossover study of healthy young volunteers. Environ Health Perspect 123:310–316; http://dx.doi.org/10.1289/ehp.1307986 PMID:25514459

Differential Proteomic Analysis Reveals the Effect of Calcium on Malus baccata Borkh. Leaves under Temperature Stress.

PubMed

Li, Lijie; Su, Hong; Ma, Huaiyu; Lyu, Deguo

2017-08-11

In the cool apple-producing areas of northern China, air temperature during early spring changes in a rapid and dramatic manner, which affects the growth and development of apple trees at the early stage of the growing season. Previous studies have shown that the treatment of calcium can increase the cold tolerance of Malus baccata Borkh., a widely-used rootstock apple tree in northern China. To better understand the physiological function of calcium in the response of M. baccata to temperature stress, we analyzed the effect of calcium treatment (2% CaCl₂) on M. baccata leaves under temperature stress. Physiological analysis showed that temperature stress aggravated membrane lipid peroxidation, reduced chlorophyll content and induced photo-inhibition in leaves, whereas these indicators of stress injuries were alleviated by the application of calcium. An isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics approach was used in this study. Among the 2114 proteins that were detected in M. baccata leaves, 41, 25, and 34 proteins were differentially regulated by the increasing, decreasing, and changing temperature treatments, respectively. Calcium treatment induced 9 and 15 proteins after increasing and decreasing temperature, respectively, in comparison with non-treated plants. These calcium-responsive proteins were mainly related to catalytic activity, binding, and structural molecule activity. Hierarchical cluster analysis indicated that the changes in abundance of the proteins under increasing temperature and changing temperature treatments were similar, and the changes in protein abundance under decreasing temperature and increasing temperature with calcium treatment were similar. The findings of this study will allow a better understanding of the mechanisms underlying the role of calcium in M. baccata leaves under temperature stress.

Differential Proteomic Analysis Reveals the Effect of Calcium on Malus baccata Borkh. Leaves under Temperature Stress

PubMed Central

Li, Lijie; Su, Hong; Ma, Huaiyu; Lyu, Deguo

2017-01-01

In the cool apple-producing areas of northern China, air temperature during early spring changes in a rapid and dramatic manner, which affects the growth and development of apple trees at the early stage of the growing season. Previous studies have shown that the treatment of calcium can increase the cold tolerance of Malus baccata Borkh., a widely-used rootstock apple tree in northern China. To better understand the physiological function of calcium in the response of M. baccata to temperature stress, we analyzed the effect of calcium treatment (2% CaCl2) on M. baccata leaves under temperature stress. Physiological analysis showed that temperature stress aggravated membrane lipid peroxidation, reduced chlorophyll content and induced photo-inhibition in leaves, whereas these indicators of stress injuries were alleviated by the application of calcium. An isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics approach was used in this study. Among the 2114 proteins that were detected in M. baccata leaves, 41, 25, and 34 proteins were differentially regulated by the increasing, decreasing, and changing temperature treatments, respectively. Calcium treatment induced 9 and 15 proteins after increasing and decreasing temperature, respectively, in comparison with non-treated plants. These calcium-responsive proteins were mainly related to catalytic activity, binding, and structural molecule activity. Hierarchical cluster analysis indicated that the changes in abundance of the proteins under increasing temperature and changing temperature treatments were similar, and the changes in protein abundance under decreasing temperature and increasing temperature with calcium treatment were similar. The findings of this study will allow a better understanding of the mechanisms underlying the role of calcium in M. baccata leaves under temperature stress. PMID:28800123

Anther response to high-temperature stress during development and pollen thermotolerance heterosis as revealed by pollen tube growth and in vitro pollen vigor analysis in upland cotton.

PubMed

Song, Guicheng; Wang, Miaomiao; Zeng, Bin; Zhang, Jing; Jiang, Chenliang; Hu, Qirui; Geng, Guangtao; Tang, Canming

2015-05-01

Pollen tube growth in styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the adverse effect of high temperatures during square development. High-temperature stress during flowering influences the square development of upland cotton (Gossypium hirsutum L.) and cotton yield. Although it is well known that square development is sensitive to high temperature, high-temperature sensitive stages of square development and the effects of high temperature on pollen tube growth in the styles are unknown. The effect of high temperature on anther development corresponding to pollen vigor is unknown during anther development. The objectives of this study were to identify the stages of square development that are sensitive to high temperatures (37/30 and 40/34 °C), to determine whether the abnormal development of squares influenced by high temperature is responsible for the variation in the in vitro germination percent of pollen grains at anthesis, to identify the effect of high temperature on pollen germination in the styles, and to determine pollen thermotolerance heterosis. Our results show that the stages from the sporogenous cell to tetrad stage (square length <6.0 mm) were the most sensitive to high temperature, and the corresponding pollen viability at anthesis was consistent with the changes in the square development stage. Pollen tube growth in the styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the effect of high temperature during square development. The thermotolerance of hybrid F1 pollen showed heterosis, and pollen viability could be used as a criterion for screening for high-temperature tolerance cultivars. These results can be used in breeding to develop new cotton cultivars that can withstand high-temperature conditions, particularly in a future warmer climate.

Effect on orange juice of batch pasteurization in an improved pilot-scale microwave oven.

PubMed

Cinquanta, L; Albanese, D; Cuccurullo, G; Di Matteo, M

2010-01-01

The effects on orange juice batch pasteurization in an improved pilot-scale microwave (MW) oven was evaluated by monitoring pectin methyl-esterase (PME) activity, color, carotenoid compounds and vitamin C content. Trials were performed on stirred orange juice heated at different temperatures (60, 70, 75, and 85 degrees C) during batch process. MW pilot plant allowed real-time temperature control of samples using proportional integrative derivative (PID) techniques based on the infrared thermography temperature read-out. The inactivation of heat sensitive fraction of PME, that verifies orange juice pasteurization, showed a z-value of 22.1 degrees C. Carotenoid content, responsible for sensorial and nutritional quality in fresh juices, decreased by about 13% after MW pasteurization at 70 degrees C for 1 min. Total of 7 carotenoid compounds were quantified during MW heating: zeaxanthin and beta-carotene content decreased by about 26%, while no differences (P < 0.05) were found for beta-cryptoxanthin in the same trial. A slight decrease in vitamin C content was monitored after MW heating. Results showed that MW heating with a fine temperature control could result in promising stabilization treatments.

The effect of monomolecular surface films on the microwave brightness temperature of the sea surface

NASA Technical Reports Server (NTRS)

Alpers, W.; Blume, H.-J. C.; Garrett, W. D.; Huehnerfuss, H.

1982-01-01

It is pointed out that monomolecular surface films of biological origin are often encountered on the ocean surface, especially in coastal regions. The thicknesses of the monomolecular films are of the order of 3 x 10 to the -9th m. Huehnerfuss et al. (1978, 1981) have shown that monomolecular surface films damp surface waves quite strongly in the centimeter to decimeter wavelength regime. Other effects caused by films are related to the reduction of the gas exchange at the air-sea interface and the decrease of the wind stress. The present investigation is concerned with experiments which reveal an unexpectedly large response of the microwave brightness temperature to a monomolecular oleyl alcohol slick at 1.43 GHz. Brightness temperature is a function of the complex dielectric constant of thy upper layer of the ocean. During six overflights over an ocean area covered with an artificial monomolecular alcohol film, a large decrease of the brightness temperature at the L-band was measured, while at the S-band almost no decrease was observed.

Low temperature effects on nitrification and nitrifier community structure in V-ASP for decentralized wastewater treatment and its improvement by bio-augmentation.

PubMed

Yuan, Jiajia; Dong, Wenyi; Sun, Feiyun; Zhao, Ke

2018-03-01

The vegetation-activated sludge process (V-ASP) has been proved to be an environment-friendly decentralized wastewater treatment system with extra esthetic function and less footprint. However, the effects of low temperature on the treatment performance of V-ASP and related improvement methods are rarely investigated, up to now. In this work, the effect of low temperature on nitrification in V-ASP was comprehensively investigated from overall nitrification performance, substrate utilization kinetics, functional enzymatic activities, and microbial community structure shift by comparison with conventional ASP. Bio-augmentation methods in terms of single-time nitrifier-enriched biomass dosage were employed to improve nitrification efficiency in bench- and full-scale systems. The experiment results demonstrated that the NH 4 + -N removal efficiency in V-ASP system decreased when the operational temperature decreased from 30 to 15 °C, and the decreasing extent was rather smaller compared to ASP, as well as ammonium and nitrite oxidation rates and enzymatic activities, which indicated the V-ASP system possesses high resistance to low temperature. With direct dosage of 1.6 mg nitrifier/gSS sludge, the nitrification efficiency in V-ASP was enhanced dramatically from below 50% to above 90%, implying that bio-augmentation was effective for V-ASP whose enzymatic activities and microbial communities were both also improved. The feasibility and effectiveness of bio-augmentation was further confirmed in a full-scale V-ASP system after a long-term experiment which is instructive for the practical application.

Simulating the impacts of chronic ozone exposure on plant conductance and photosynthesis, and on the regional hydroclimate using WRF/Chem

NASA Astrophysics Data System (ADS)

Li, Jialun; Mahalov, Alex; Hyde, Peter

2016-11-01

The Noah-Multiparameterization land surface model in the Weather Research and Forecasting (WRF) with Chemistry (WRF/Chem) is modified to include the effects of chronic ozone exposure (COE) on plant conductance and photosynthesis (PCP) found from field experiments. Based on the modified WRF/Chem, the effects of COE on regional hydroclimate have been investigated over the continental United States. Our results indicate that the model with/without modification in its current configuration can reproduce the rainfall and temperature patterns of the observations and reanalysis data, although it underestimates rainfall in the central Great Plains and overestimates it in the eastern coast states. The experimental tests on the effects of COE include setting different thresholds of ambient ozone concentrations ([O3]) and using different linear regressions to quantify PCP against the COE. Compared with the WRF/Chem control run (i.e., without considering the effects of COE), the modified model at different experiment setups improves the simulated estimates of rainfall and temperatures in Texas and regions to the immediate north. The simulations in June, July and August of 2007-2012 show that surface [O3] decrease latent heat fluxes (LH) by 10-27 W m-2, increase surface air temperatures (T 2) by 0.6 °C-2.0 °C, decrease rainfall by 0.9-1.4 mm d-1, and decrease runoff by 0.1-0.17 mm d-1 in Texas and surrounding areas, all of which highly depends on the precise experiment setup, especially the [O3] threshold. The mechanism producing these results is that COE decreases the LH and increases sensible heat fluxes, which in turn increases the Bowen ratios and air temperatures. This lowering of the LH also results in the decrease of convective potential and finally decreases convective rainfall. Employing this modified WRF/Chem model in any high [O3] region can improve the understanding of the interactions of vegetation, meteorology, chemistry/emissions, and crop productivity.

A new thermal model for bone drilling with applications to orthopaedic surgery.

PubMed

Lee, JuEun; Rabin, Yoed; Ozdoganlar, O Burak

2011-12-01

This paper presents a new thermal model for bone drilling with applications to orthopaedic surgery. The new model combines a unique heat-balance equation for the system of the drill bit and the chip stream, an ordinary heat diffusion equation for the bone, and heat generation at the drill tip, arising from the cutting process and friction. Modeling of the drill bit-chip stream system assumes an axial temperature distribution and a lumped heat capacity effect in the transverse cross-section. The new model is solved numerically using a tailor-made finite-difference scheme for the drill bit-chip stream system, coupled with a classic finite-difference method for the bone. The theoretical investigation addresses the significance of heat transfer between the drill bit and the bone, heat convection from the drill bit to the surroundings, and the effect of the initial temperature of the drill bit on the developing thermal field. Using the new model, a parametric study on the effects of machining conditions and drill-bit geometries on the resulting temperature field in the bone and the drill bit is presented. Results of this study indicate that: (1) the maximum temperature in the bone decreases with increased chip flow; (2) the transient temperature distribution is strongly influenced by the initial temperature; (3) the continued cooling (irrigation) of the drill bit reduces the maximum temperature even when the tip is distant from the cooled portion of the drill bit; and (4) the maximum temperature increases with increasing spindle speed, increasing feed rate, decreasing drill-bit diameter, increasing point angle, and decreasing helix angle. The model is expected to be useful in determination of optimum drilling conditions and drill-bit geometries. Copyright © 2011. Published by Elsevier Ltd.

Role of SiO2 coating in multiferroic CoCr2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Kamran, M.; Ullah, Asmat; Mehmood, Y.; Nadeem, K.; Krenn, H.

2017-02-01

Effect of silica (SiO2) coating concentration on structural and magnetic properties of multiferroic cobalt chromite (CoCr2O4) nanoparticles have been studied. The nanoparticles with average crystallite size in the range 19 to 28 nm were synthesised by sol-gel method. X-ray diffraction (XRD) analysis has verified the composition of single-phase cubic normal spinel structure of CoCr2O4 nanoparticles. The average crystallite size and cell parameter decreased with increasing SiO2 concentration. TEM image revealed that the shape of nanoparticles was non-spherical. Zero field cooled/field cooled (ZFC/FC) curves revealed that nanoparticles underwent a transition from paramagnetic (PM) state to collinear short-range ferrimagnetic (FiM) state, and this PM-FiM transition temperature decreased from 101 to 95 K with increasing SiO2 concentration or decreasing crystallite size. A conical spin state at Ts = 27 K was also observed for all the samples which decreased with decreasing average crystallite size. Low temperature lock-in transition was also observed in these nanoparticles at 12 K for uncoated nanoparticles which slightly shifted towards low temperature with decreasing average crystallite size. Saturation magnetization (Ms) showed decreasing trend with increasing SiO2 concentration, which was due to decrease in average crystallite size of nanoparticles and enhanced surface disorder in smaller nanoparticles. The temperature dependent AC-susceptibility also showed the decrease in the transition temperature (Tc), broadening of the Tc peak and decrease in magnetization with increasing SiO2 concentration or decreasing average crystallite size. In summary, the concentration of SiO2 has significantly affected the structural and magnetic properties of CoCr2O4 nanoparticles.

Effects of seawater flow rate and evaporation temperature on performance of Sherbet type ice making machine

NASA Astrophysics Data System (ADS)

Son, C. H.; Yoon, J. I.; Choi, K. H.; Lee, H. K.; Lee, K. S.; Moon, C. G.; Seol, S. H.

2018-01-01

This study analyzes performance of the sherbet type ice making machine using seawater with respect to seawater volumetric flow rate, evaporation temperature, cooling water inlet and seawater inlet temperature as variables. Cooling water inlet and seawater inlet temperature are set considering average temperature of South Korea and the equator regions. Volumetric flow rate of seawater range is 0.75-1.75 LPM in this experiment. The results obtained from the experiment are as follows. As the seawater volumetric flow rate increases, or seawater inlet temperature increases, evaporation capacity tends to increase. At the point of seawater inlet temperature of 27°C and volumetric flow rate of 1.0LPM, evaporation capacity is over 2kW. On the other hand, results of COP change tendency are different from that of evaporation capacity. It appears to increase until volumetric flow rate of 1.0LPM, and decrease gradually from volumetric flow rate of 1.5LPM. This is due to the increase of compressor work to keep the evaporation pressure in accordance with the temperature of heat source. As the evaporation temperature decreases from -8 to -15°C, the evaporation capacity increases, but the COP decreases.

Magnetic and transport properties of amorphous Ce-Al alloy

NASA Astrophysics Data System (ADS)

Amakai, Yusuke; Murayama, Shigeyuki; Momono, Naoki; Takano, Hideaki; Kuwai, Tomohiko

2018-05-01

Amorphous (a-)Ce50Al50 has been prepared by DC high-rate sputter method. The structure of the obtained sample has been confirmed to have an amorphous structure because there are no Bragg peaks in the X-ray diffraction measurement and have a clear exothermic peak by the differential scanning calorimetry measurement. We have measured the resistivity ρ, magnetic susceptibility χ, specific heat Cp and thermoelectric power S for a-Ce50Al50. The temperature dependence of ρ exhibits a small temperature dependence less than 10% in the whole temperature region. χ follows a Curie-Weiss behavior in the high-temperature region of T>90 K. The effective paramagnetic moment peff, estimated from C is 2.18 μB/Ce-atom. The low-temperature Cp/T increases rapidly with decreasing temperature and tends to a saturation. S(T) exhibits negative values in a wide temperature region. A minimum of S appear at around 60 K, and S decreases linearly with decreasing temperature down to 10 K. The low-temperature S is almost 0 μV/K down to 2 K. From these results, we have pointed out that present a-Ce50Al50 would be an incoherent Kondo material.

Temperature modulates the response of the thermophilous sea urchin Arbacia lixula early life stages to CO2-driven acidification.

PubMed

Gianguzza, Paola; Visconti, Giulia; Gianguzza, Fabrizio; Vizzini, Salvatrice; Sarà, Gianluca; Dupont, Sam

2014-02-01

The increasing abundances of the thermophilous black sea urchin Arbacia lixula in the Mediterranean Sea are attributed to the Western Mediterranean warming. However, few data are available on the potential impact of this warming on A. lixula in combination with other global stressors such as ocean acidification. The aim of this study is to investigate the interactive effects of increased temperature and of decreased pH on fertilization and early development of A. lixula. This was tested using a fully crossed design with four temperatures (20, 24, 26 and 27 °C) and two pH levels (pHNBS 8.2 and 7.9). Temperature and pH had no significant effect on fertilization and larval survival (2d) for temperature <27 °C. At 27 °C, the fertilization success was very low (<1%) and all larvae died within 2d. Both temperature and pH had effects on the developmental dynamics. Temperature appeared to modulate the impact of decreasing pH on the % of larvae reaching the pluteus stage leading to a positive effect (faster growth compared to pH 8.2) of low pH at 20 °C, a neutral effect at 24 °C and a negative effect (slower growth) at 26 °C. These results highlight the importance of considering a range of temperatures covering today and the future environmental variability in any experiment aiming at studying the impact of ocean acidification. Copyright © 2013 Elsevier Ltd. All rights reserved.

Daily average temperature and mortality among the elderly: a meta-analysis and systematic review of epidemiological evidence

NASA Astrophysics Data System (ADS)

Yu, Weiwei; Mengersen, Kerrie; Wang, Xiaoyu; Ye, Xiaofang; Guo, Yuming; Pan, Xiaochuan; Tong, Shilu

2012-07-01

The impact of climate change on the health of vulnerable groups such as the elderly has been of increasing concern. However, to date there has been no meta-analysis of current literature relating to the effects of temperature fluctuations upon mortality amongst the elderly. We synthesised risk estimates of the overall impact of daily mean temperature on elderly mortality across different continents. A comprehensive literature search was conducted using MEDLINE and PubMed to identify papers published up to December 2010. Selection criteria including suitable temperature indicators, endpoints, study-designs and identification of threshold were used. A two-stage Bayesian hierarchical model was performed to summarise the percent increase in mortality with a 1°C temperature increase (or decrease) with 95% confidence intervals in hot (or cold) days, with lagged effects also measured. Fifteen studies met the eligibility criteria and almost 13 million elderly deaths were included in this meta-analysis. In total, there was a 2-5% increase for a 1°C increment during hot temperature intervals, and a 1-2 % increase in all-cause mortality for a 1°C decrease during cold temperature intervals. Lags of up to 9 days in exposure to cold temperature intervals were substantially associated with all-cause mortality, but no substantial lagged effects were observed for hot intervals. Thus, both hot and cold temperatures substantially increased mortality among the elderly, but the magnitude of heat-related effects seemed to be larger than that of cold effects within a global context.

Cosmic rays and other rpace phenomena influenced on the Earth's climate

NASA Astrophysics Data System (ADS)

Lev, Dorman

2016-07-01

We consider effects of cosmic rays (CR) and some other space phenomena on the Earth's climate change. It is well known that the system of internal and external factors formatting the Earth's climate is very unstable: decreasing of planetary average annual temperature leads to an increase of planetary snow surface, and decreasing of the total annual solar energy input into the system decreases the planetary temperature even more. And inverse: increasing planetary temperature leads to an decrease of snow surface, and increasing of the total solar energy input into the system increases the planetary temperature even more. From this follows that even energetically small factors acted long time in one direction may have a big influence on climate change. In our opinion, the most important of these factors are CR (mostly through its influence on planetary cloudiness) and space dust (SD) through their influence on the flux of solar irradiation and on formation of clouds (these actions are in one direction). It is important that CR and SD influenced on global climate change in the same direction. Increasing of CR planetary intensity leads to increasing of formation clouds (especially low clouds on altitudes smaller than 3 km), increasing annual average of raining and decreasing of annual average planetary temperature. Increasing of SD decreases of solar irradiation and increases cloudiness what leads also to decreasing of annual average planetary temperature. Moreover, interactions of CR particles with dust granules decreases their dimensions what increased effectiveness of their actions on clouds. We consider data great variations of planetary temperature much before the beginning of the Earth's technological civilization (mostly caused by moving of the solar system around our Galaxy centre and collisions with molecular-dust clouds). We consider in details not only situation during the last hundred years, but also situation in the last one thousand years (and especially situation during Maunder minimum of solar activity), during many thousand and many millions years. It is shown that very big changes in climate were caused also by some rarely phenomena as impacts of asteroids and nearby supernova explosions with great influence on biosphere. We discuss also the problem on forecasting of global climate change what is especially important for saving present civilization from great climate catastrophes.

Potential changes in bacterial metabolism associated with increased water temperature and nutrient inputs in tropical humic lagoons.

PubMed

Scofield, Vinicius; Jacques, Saulo M S; Guimarães, Jean R D; Farjalla, Vinicius F

2015-01-01

Temperature and nutrient concentrations regulate aquatic bacterial metabolism. However, few studies have focused on the effect of the interaction between these factors on bacterial processes, and none have been performed in tropical aquatic ecosystems. We analyzed the main and interactive effects of changes in water temperature and N and P concentrations on bacterioplankton production (BP), bacterioplankton respiration (BR) and bacterial growth efficiency (BGE) in tropical coastal lagoons. We used a factorial design with three levels of water temperature (25, 30, and 35°C) and four levels of N and/or P additions (Control, N, P, and NP additions) in five tropical humic lagoons. When data for all lagoons were pooled together, a weak interaction was observed between the increase in water temperature and the addition of nutrients. Water temperature alone had the greatest impact on bacterial metabolism by increasing BR, decreasing BP, and decreasing BGE. An increase of 1°C lead to an increase of ~4% in BR, a decrease of ~0.9% in BP, and a decrease of ~4% in BGE. When data were analyzed separately, lagoons responded differently to nutrient additions depending on Dissolved Organic Carbon (DOC) concentration. Lagoons with lowest DOC concentrations showed the strongest responses to nutrient additions: BP increased in response to N, P, and their interaction, BR increased in response to N and the interaction between N and P, and BGE was negatively affected, mainly by the interaction between N and P additions. Lagoons with the highest DOC concentrations showed almost no significant relationship with nutrient additions. Taken together, these results show that different environmental drivers impact bacterial processes at different scales. Changes of bacterial metabolism related to the increase of water temperature are consistent between lagoons, therefore their consequences can be predicted at a regional scale, while the effect of nutrient inputs is specific to different lagoons but seems to be related to the DOC concentration.

Potential changes in bacterial metabolism associated with increased water temperature and nutrient inputs in tropical humic lagoons

PubMed Central

Scofield, Vinicius; Jacques, Saulo M. S.; Guimarães, Jean R. D.; Farjalla, Vinicius F.

2015-01-01

Temperature and nutrient concentrations regulate aquatic bacterial metabolism. However, few studies have focused on the effect of the interaction between these factors on bacterial processes, and none have been performed in tropical aquatic ecosystems. We analyzed the main and interactive effects of changes in water temperature and N and P concentrations on bacterioplankton production (BP), bacterioplankton respiration (BR) and bacterial growth efficiency (BGE) in tropical coastal lagoons. We used a factorial design with three levels of water temperature (25, 30, and 35°C) and four levels of N and/or P additions (Control, N, P, and NP additions) in five tropical humic lagoons. When data for all lagoons were pooled together, a weak interaction was observed between the increase in water temperature and the addition of nutrients. Water temperature alone had the greatest impact on bacterial metabolism by increasing BR, decreasing BP, and decreasing BGE. An increase of 1°C lead to an increase of ~4% in BR, a decrease of ~0.9% in BP, and a decrease of ~4% in BGE. When data were analyzed separately, lagoons responded differently to nutrient additions depending on Dissolved Organic Carbon (DOC) concentration. Lagoons with lowest DOC concentrations showed the strongest responses to nutrient additions: BP increased in response to N, P, and their interaction, BR increased in response to N and the interaction between N and P, and BGE was negatively affected, mainly by the interaction between N and P additions. Lagoons with the highest DOC concentrations showed almost no significant relationship with nutrient additions. Taken together, these results show that different environmental drivers impact bacterial processes at different scales. Changes of bacterial metabolism related to the increase of water temperature are consistent between lagoons, therefore their consequences can be predicted at a regional scale, while the effect of nutrient inputs is specific to different lagoons but seems to be related to the DOC concentration. PMID:25926827

Respiratory properties of blood and arterial blood gases in the tegu lizard: effects of temperature and hypercapnia.

PubMed

Wood, S C; Glass, M L; Andersen, N A; Heisler, N

1987-01-01

The effects of body temperature and hypercapnia (7% inspired CO2) on arterial blood gases, plasma pH, and the characteristics of the blood oxygen dissociation curve were determined in Tegu lizards (Tupinambis nigropunctatus). Arterial pH fell from 7.59 to 7.50 when body temperature was increased from 25 to 35 degrees C. The pH/temperature coefficient (delta pH/delta t = -0.009 U/degrees C) was half of that predicted on the basis of 'constant relative alkalinity' and the alphastat hypothesis. The fall in plasma pH resulted from a decrease in plasma [HCO3-], and a rise in plasma Pco2. The O2 affinity of Tegu blood, expressed by the partial pressure at half saturation (P50), decreased with temperature in vitro from 42.3 to 49.6 torr at pH 7.4. The apparent enthalpy (delta H = -3.1 kcal/mol) is about 1/4 of that of human blood. In vivo, the arterial blood oxygen saturation decreased from 89% at 25 degrees to 82% at 35 degrees C. Arterial Po2 increased from 61 to 71 torr as expected from the right-shift of the oxygen dissociation curve. During environmental hypercapnia (7% CO2, 21% O2, 72% N2 inspired concentrations), arterial pH decreased to 7.28. Arterial O2 saturation remained constant and arterial Po2 increased from 61 to 85 torr due to the right-shift of the oxygen dissociation curve. The comparatively small effect of changes in temperature on the oxygen affinity of Tegu blood (directly according to the delta H value, and indirectly via changes in blood pH) results in a relatively small right shift of the oxygen dissociation curve, and accordingly in relatively high arterial and tissue Po2 values also at higher temperatures.

Effect of the solution temperature in a singlet-oxygen generator on the formation of active medium in an ejector oxygen - iodine laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagidullin, M V; Nikolaev, V D; Svistun, M I

2002-02-28

The influence of the solution temperature in a singlet-oxygen generator on the formation of the active medium in the ejector oxygen - iodine laser is investigated. The following parameters of the active medium at the solution temperature -20{sup 0}C are obtained: the gain is 7.2 x 10{sup -3} cm{sup -1}, the Mach number is M=2, the temperature is 205 K, and the static pressure is 9.3 mmHg. As the solution temperature is increased to -4{sup 0}C, the gain decreases to 5 x 10{sup 3} cm{sup -1}, the Mach number decreases to 1.78, while the temperature and the static pressure increasemore » to 241 K and 10.7 mmHg, respectively. As the solution temperature increases from -20 to -4{sup 0}C, the losses in O{sub 2}({sup 1}{Delta}) increase by less than 20%, while the dissociation efficiency of molecular iodine decreases by less than 21%. (lasers, active media)« less

Performance and Reliability of Solid Tantalum Capacitors at Cryogenic Conditions

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander

2006-01-01

Performance of different types of solid tantalum capacitors was evaluated at room and low temperatures, down to 15 K. The effect of temperature on frequency dependencies of capacitance, effective series resistances (ESR), leakage currents, and breakdown voltages has been investigated and analyzed. To assess thermo-mechanical robustness of the parts, several groups of loose capacitors and those soldered on FR4 boards were subjected to multiple (up to 500) temperature cycles between room temperature and 77 K. Experiments and mathematical modeling have shown that degradation in tantalum capacitors at low temperatures is mostly due to increasing resistance of the manganese cathode layer, resulting in substantial decrease of the roll-off frequency. Absorption currents follow a power law, I approximately t(sup -m), with the exponent m varying from 0.8 to 1.1. These currents do not change significantly at cryogenic conditions and the value of the exponent remains the same down to 15 K. Variations of leakage currents with voltage can be described by Pool-Frenkel and Schottky mechanisms of conductivity, with the Schottky mechanism prevailing at cryogenic conditions. Breakdown voltages of tantalum capacitors increase and the probability of scintillations decreases at cryogenic temperatures. However, breakdown voltages measured during surge current testing decrease at liquid nitrogen (LN) compared to room-temperature conditions. Results of temperature cycling suggest that tantalum capacitors are capable of withstanding multiple exposures to cryogenic conditions, but the probability of failures varies for different part types.

The effect of various sintering temperature on used refractory towards its physical properties

NASA Astrophysics Data System (ADS)

Sudibyo; Wulandari, Y. R.; Amin, M.; Azhar

2018-01-01

The used magnesia refractory from the kiln of cement industry was successfully recycled to new refractory using Kaolin as an adhesive. In this work, the temperatures of sintering were varied from 1000°C to 1500°C. The result shows that the increment temperature effects in sintering process will enhance refractory physical properties such as bulk density, cold crushing strength or pressure strength and thermal conductivity. Meanwhile, the porosity was decreased as the increase of the sintering temperature.

Response of water temperatures and stratification to changing climate in three lakes with different morphometry

NASA Astrophysics Data System (ADS)

Magee, Madeline R.; Wu, Chin H.

2017-12-01

Water temperatures and stratification are important drivers for ecological and water quality processes within lake systems, and changes in these with increases in air temperature and changes to wind speeds may have significant ecological consequences. To properly manage these systems under changing climate, it is important to understand the effects of increasing air temperatures and wind speed changes in lakes of different depths and surface areas. In this study, we simulate three lakes that vary in depth and surface area to elucidate the effects of the observed increasing air temperatures and decreasing wind speeds on lake thermal variables (water temperature, stratification dates, strength of stratification, and surface heat fluxes) over a century (1911-2014). For all three lakes, simulations showed that epilimnetic temperatures increased, hypolimnetic temperatures decreased, the length of the stratified season increased due to earlier stratification onset and later fall overturn, stability increased, and longwave and sensible heat fluxes at the surface increased. Overall, lake depth influences the presence of stratification, Schmidt stability, and differences in surface heat flux, while lake surface area influences differences in hypolimnion temperature, hypolimnetic heating, variability of Schmidt stability, and stratification onset and fall overturn dates. Larger surface area lakes have greater wind mixing due to increased surface momentum. Climate perturbations indicate that our larger study lakes have more variability in temperature and stratification variables than the smaller lakes, and this variability increases with larger wind speeds. For all study lakes, Pearson correlations and climate perturbation scenarios indicate that wind speed has a large effect on temperature and stratification variables, sometimes greater than changes in air temperature, and wind can act to either amplify or mitigate the effect of warmer air temperatures on lake thermal structure depending on the direction of local wind speed changes.

Chiral crossover transition in a finite volume

NASA Astrophysics Data System (ADS)

Shi, Chao; Jia, Wenbao; Sun, An; Zhang, Liping; Zong, Hongshi

2018-02-01

Finite volume effects on the chiral crossover transition of strong interactions at finite temperature are studied by solving the quark gap equation within a cubic volume of finite size L. With the anti-periodic boundary condition, our calculation shows the chiral quark condensate, which characterizes the strength of dynamical chiral symmetry breaking, decreases as L decreases below 2.5 fm. We further study the finite volume effects on the pseudo-transition temperature {T}{{c}} of the crossover, showing a significant decrease in {T}{{c}} as L decreases below 3 fm. Supported by National Natural Science Foundation of China (11475085, 11535005, 11690030, 51405027), the Fundamental Research Funds for the Central Universities (020414380074), China Postdoctoral Science Foundation (2016M591808) and Open Research Foundation of State Key Lab. of Digital Manufacturing Equipment & Technology in Huazhong University of Science & Technology (DMETKF2015015)

Simulated responses of terrestrial aridity to black carbon and sulfate aerosols

NASA Astrophysics Data System (ADS)

Lin, L.; Gettelman, A.; Xu, Y.; Fu, Q.

2016-01-01

Aridity index (AI), defined as the ratio of precipitation to potential evapotranspiration (PET), is a measure of the dryness of terrestrial climate. Global climate models generally project future decreases of AI (drying) associated with global warming scenarios driven by increasing greenhouse gas and declining aerosols. Given their different effects in the climate system, scattering and absorbing aerosols may affect AI differently. Here we explore the terrestrial aridity responses to anthropogenic black carbon (BC) and sulfate (SO4) aerosols with Community Earth System Model simulations. Positive BC radiative forcing decreases precipitation averaged over global land at a rate of 0.9%/°C of global mean surface temperature increase (moderate drying), while BC radiative forcing increases PET by 1.0%/°C (also drying). BC leads to a global decrease of 1.9%/°C in AI (drying). SO4 forcing is negative and causes precipitation a decrease at a rate of 6.7%/°C cooling (strong drying). PET also decreases in response to SO4 aerosol cooling by 6.3%/°C cooling (contributing to moistening). Thus, SO4 cooling leads to a small decrease in AI (drying) by 0.4%/°C cooling. Despite the opposite effects on global mean temperature, BC and SO4 both contribute to the twentieth century drying (AI decrease). Sensitivity test indicates that surface temperature and surface available energy changes dominate BC- and SO4-induced PET changes.

Effects of melatonin and green-wavelength LED light on the physiological stress and immunity of goldfish, Carassius auratus, exposed to high water temperature.

PubMed

Jung, Seo Jin; Kim, Na Na; Choi, Young Jae; Choi, Ji Yong; Choi, Young-Ung; Heo, Youn Seong; Choi, Cheol Young

2016-10-01

This study investigated the effects of increasing water temperature (22-30 °C) on the physiological stress response and immunity of goldfish, Carassius auratus, and the ability of green light-emitting diode (LED) irradiation or melatonin injections to mitigate this temperature-induced stress. To evaluate the effects of either green-wavelength LED light or melatonin on stress in goldfish, we measured plasma triiodothyronine (T3), thyroxine (T4), and thyroid hormone receptor (TR) mRNA expression; plasma cortisol and glucose; and immunoglobulin M (IgM) and lysozyme mRNA expression. The thyroid hormone activities, TR mRNA expression, and plasma cortisol and glucose were higher in goldfish exposed to high-temperature water, but were lower after exposure to melatonin or green-wavelength LED light. Lysozyme mRNA expression and plasma IgM activity and protein expression were lower after exposure to high water temperatures and higher after melatonin or green-wavelength LED light treatments. Therefore, high water temperature induced stress and decreased immunity; however, green-wavelength LED light and melatonin treatments mitigated the effects of stress and enhanced immunity. The benefits of melatonin decreased with time, whereas those of green-wavelength LED treatment did not.

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

PubMed Central

Mantzouki, Evanthia; Fastner, Jutta; de Senerpont Domis, Lisette; Wilk-Woźniak, Elżbieta; Koreivienė, Judita; Verstijnen, Yvon; Krztoń, Wojciech; Walusiak, Edward; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova, Ksenija; Vitonytė, Irma; Budzyńska, Agnieszka; Szeląg-Wasielewska, Elżbieta; Domek, Piotr; Messyasz, Beata; Pełechata, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; García-Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero-Ribes, Jordi; Duque, David Parreño; Karakaya, Nusret; Häggqvist, Kerstin; Beklioğlu, Meryem; Filiz, Nur; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Panou, Manthos; Fakioglu, Özden; Avagianos, Christos; Çelik, Kemal; Yilmaz, Mete; Marcé, Rafael; Buck, Moritz; Colom-Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Raposeiro, Pedro M.; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Feldmann, Tõnu; Panksep, Kristel; Tuvikene, Lea; Gagala, Ilona; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Boscaini, Adriano; Cerasino, Leonardo; Richardson, Jessica; Visser, Petra M.; Verspagen, Jolanda M. H.; Karan, Tünay; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Köker, Latife; Albay, Meriç; Maronić, Dubravka Špoljarić; Stević, Filip; Pfeiffer, Tanja Žuna; Fonvielle, Jeremy; Rothhaupt, Karl-Otto; Hansson, Lars-Anders; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Koçer, Mehmet Ali Turan; Alp, Mehmet Tahir; Remec-Rekar, Spela; Elersek, Tina; Hiskia, Anastasia; Haande, Sigrid; Skjelbred, Birger; Madrecka, Beata; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Edwards, Christine; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Aleksovski, Boris; Krstić, Svetislav; Vucelić, Itana Bokan; Nawrocka, Lidia; Salmi, Pauliina; Machado-Vieira, Danielle; de Oliveira, Alinne Gurjão; Delgado-Martín, Jordi; García, David; Cereijo, Jose Luís; Trapote, Mari Carmen; Obrador, Biel; Grabowska, Magdalena; Chmura, Damian; Úbeda, Bárbara; Warming, Trine Perlt; Kobos, Justyna; Mazur-Marzec, Hanna; Arvola, Lauri; Alcaraz-Párraga, Pablo; Toporowska, Magdalena; Pawlik-Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Moreno-Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes-Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez-Pérez, Estela; Carballeira, Rafael; Picazo, Antonio; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kostrzewska-Szlakowska, Iwona; Jasser, Iwona; Žutinić, Petar; Udovič, Marija Gligora; Plenković-Moraj, Anđelka; Frąk, Magdalena; Bańkowska-Sobczak, Agnieszka; Wasilewicz, Michał; Özkan, Korhan; Kangro, Kersti; Ibelings, Bas W.

2018-01-01

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. PMID:29652856

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins.

PubMed

Mantzouki, Evanthia; Lürling, Miquel; Fastner, Jutta; de Senerpont Domis, Lisette; Wilk-Woźniak, Elżbieta; Koreivienė, Judita; Seelen, Laura; Teurlincx, Sven; Verstijnen, Yvon; Krztoń, Wojciech; Walusiak, Edward; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova, Ksenija; Vitonytė, Irma; Cillero-Castro, Carmen; Budzyńska, Agnieszka; Goldyn, Ryszard; Kozak, Anna; Rosińska, Joanna; Szeląg-Wasielewska, Elżbieta; Domek, Piotr; Jakubowska-Krepska, Natalia; Kwasizur, Kinga; Messyasz, Beata; Pełechaty, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; García-Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero-Ribes, Jordi; Duque, David Parreño; Fernández-Morán, Elísabeth; Karakaya, Nusret; Häggqvist, Kerstin; Demir, Nilsun; Beklioğlu, Meryem; Filiz, Nur; Levi, Eti E.; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Özhan, Koray; Gkelis, Spyros; Panou, Manthos; Fakioglu, Özden; Avagianos, Christos; Kaloudis, Triantafyllos; Çelik, Kemal; Yilmaz, Mete; Marcé, Rafael; Catalán, Nuria; Bravo, Andrea G.; Buck, Moritz; Colom-Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Raposeiro, Pedro M.; Gonçalves, Vítor; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Feldmann, Tõnu; Laas, Alo; Panksep, Kristel; Tuvikene, Lea; Gagala, Ilona; Mankiewicz-Boczek, Joana; Yağcı, Meral Apaydın; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Obertegger, Ulrike; Boscaini, Adriano; Flaim, Giovanna; Salmaso, Nico; Cerasino, Leonardo; Richardson, Jessica; Visser, Petra M.; Verspagen, Jolanda M. H.; Karan, Tünay; Soylu, Elif Neyran; Maraşlıoğlu, Faruk; Napiórkowska-Krzebietke, Agnieszka; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Antão-Geraldes, Ana M.; Vasconcelos, Vitor; Morais, João; Vale, Micaela; Köker, Latife; Akçaalan, Reyhan; Albay, Meriç; Špoljarić Maronić, Dubravka; Stević, Filip; Žuna Pfeiffer, Tanja; Fonvielle, Jeremy; Straile, Dietmar; Rothhaupt, Karl-Otto; Hansson, Lars-Anders; Urrutia-Cordero, Pablo; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Koçer, Mehmet Ali Turan; Alp, Mehmet Tahir; Remec-Rekar, Spela; Elersek, Tina; Triantis, Theodoros; Zervou, Sevasti-Kiriaki; Hiskia, Anastasia; Haande, Sigrid; Skjelbred, Birger; Madrecka, Beata; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Edwards, Christine; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Aleksovski, Boris; Krstić, Svetislav; Vucelić, Itana Bokan; Nawrocka, Lidia; Salmi, Pauliina; Machado-Vieira, Danielle; de Oliveira, Alinne Gurjão; Delgado-Martín, Jordi; García, David; Cereijo, Jose Luís; Gomà, Joan; Trapote, Mari Carmen; Vegas-Vilarrúbia, Teresa; Obrador, Biel; Grabowska, Magdalena; Karpowicz, Maciej; Chmura, Damian; Úbeda, Bárbara; Gálvez, José Ángel; Özen, Arda; Christoffersen, Kirsten Seestern; Warming, Trine Perlt; Kobos, Justyna; Mazur-Marzec, Hanna; Pérez-Martínez, Carmen; Ramos-Rodríguez, Eloísa; Arvola, Lauri; Alcaraz-Párraga, Pablo; Toporowska, Magdalena; Pawlik-Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Leira, Manel; Hernández, Armand; Moreno-Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes-Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez-Pérez, Estela; Carballeira, Rafael; Camacho, Antonio; Picazo, Antonio; Rochera, Carlos; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Soria, Juan Miguel; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kruk, Marek; Kostrzewska-Szlakowska, Iwona; Jasser, Iwona; Žutinić, Petar; Gligora Udovič, Marija; Plenković-Moraj, Anđelka; Frąk, Magdalena; Bańkowska-Sobczak, Agnieszka; Wasilewicz, Michał; Özkan, Korhan; Maliaka, Valentini; Kangro, Kersti; Grossart, Hans-Peter; Paerl, Hans W.; Carey, Cayelan C.; Ibelings, Bas W.

2018-04-13

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.

Metabolomic Analysis Using Ultra-Performance Liquid Chromatography-Quadrupole-Time of Flight Mass Spectrometry (UPLC-Q-TOF MS) Uncovers the Effects of Light Intensity and Temperature under Shading Treatments on the Metabolites in Tea

PubMed Central

Ma, Lifeng; Yi, Xiaoyun; Ruan, Jianyun

2014-01-01

To investigate the effect of light intensity and temperature on the biosynthesis and accumulation of quality-related metabolites, field grown tea plants were shaded by Black Net and Nano-insulating Film (with additional 2–4°C cooling effect) with un-shaded plants as a control. Young shoots were subjected to UPLC-Q-TOF MS followed by multivariate statistical analysis. Most flavonoid metabolites (mainly flavan-3-ols, flavonols and their glycosides) decreased significantly in the shading treatments, while the contents of chlorophyll, β-carotene, neoxanthin and free amino acids, caffeine, benzoic acid derivatives and phenylpropanoids increased. Comparison between two shading treatments indicated that the lower temperature under Nano shading decreased flavonols and their glycosides but increased accumulation of flavan-3-ols and proanthocyanidins. The comparison also showed a greater effect of temperature on galloylation of catechins than light intensity. Taken together, there might be competition for substrates between the up- and down-stream branches of the phenylpropanoid/flavonoid pathway, which was influenced by light intensity and temperature. PMID:25390340

Metabolomic analysis using ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF MS) uncovers the effects of light intensity and temperature under shading treatments on the metabolites in tea.

PubMed

Zhang, Qunfeng; Shi, Yuanzhi; Ma, Lifeng; Yi, Xiaoyun; Ruan, Jianyun

2014-01-01

To investigate the effect of light intensity and temperature on the biosynthesis and accumulation of quality-related metabolites, field grown tea plants were shaded by Black Net and Nano-insulating Film (with additional 2-4°C cooling effect) with un-shaded plants as a control. Young shoots were subjected to UPLC-Q-TOF MS followed by multivariate statistical analysis. Most flavonoid metabolites (mainly flavan-3-ols, flavonols and their glycosides) decreased significantly in the shading treatments, while the contents of chlorophyll, β-carotene, neoxanthin and free amino acids, caffeine, benzoic acid derivatives and phenylpropanoids increased. Comparison between two shading treatments indicated that the lower temperature under Nano shading decreased flavonols and their glycosides but increased accumulation of flavan-3-ols and proanthocyanidins. The comparison also showed a greater effect of temperature on galloylation of catechins than light intensity. Taken together, there might be competition for substrates between the up- and down-stream branches of the phenylpropanoid/flavonoid pathway, which was influenced by light intensity and temperature.

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...

Rheological Behavior, Granule Size Distribution and Differential Scanning Calorimetry of Cross-Linked Banana (Musa paradisiaca) Starch.

NASA Astrophysics Data System (ADS)

Núñez-Santiago, María C.; Maristany-Cáceres, Amira J.; Suárez, Francisco J. García; Bello-Pérez, Arturo

2008-07-01

Rheological behavior at 60 °C, granule size distribution and Differential Scanning Calorimetry (DSC) tests were employed to study the effect of diverse reaction conditions: adipic acid concentration, pH and temperature during cross-linking of banana (Musa paradisiaca) starch. These properties were determined in native banana starch pastes for the purpose of comparison. Rheological behavior from pastes of cross-linked starch at 60 °C did not show hysteresis, probably due the cross-linkage of starch that avoided disruption of granules, elsewhere, native starch showed hysteresis in a thixotropic loop. All pastes exhibited non-Newtonian shear thinning behavior. In all cases, size distribution showed a decrease in the median diameter in cross-linked starches. This condition produces a decrease in swelling capacity of cross-linked starch. The median diameter decreased with an increase of acid adipic concentration; however, an increase of pH and Temperature produced an increase in this variable. Finally, an increase in gelatinization temperature and entalphy (ΔH) were observed as an effect of cross-linkage. An increase in acid adipic concentration produced an increase in Tonset and a decrease in ΔH. pH and temperature. The cross-linked of banana starch produced granules more resistant during the pasting procedure.

Investigation of phase transitions in LiK 1- x(NH 4) xSO 4 mixed crystal

NASA Astrophysics Data System (ADS)

Freire, P. T. C.; Paraguassu, W.; Silva, A. P.; Pilla, O.; Teixeira, A. M. R.; Sasaki, J. M.; Mendes Filho, J.; Guedes, I.; Melo, F. E. A.

1999-02-01

We present Raman scattering results on LiK 1- x(NH 4) xSO 4 mixed crystal for temperatures between 100 and 300 K. We observed that in this temperature range the crystal undergoes two different phase transitions, which we call Bansal and Tomaszewski phase transitions. The introduction of ammonium ions in the potassium sites increases the C 66→C 3v4 (Bansal) phase transition temperature and decreases the Tomaszewski phase transition temperature. Finally, the most impressive effect of the presence of ammonium impurity in the LiKSO 4 structure is the decrease in the temperature hysteresis of Bansal phase transition and the almost complete destruction of hysteresis in the Tomaszewski phase transition, leading to a high temperature range of stability of the trigonal phase.

Effect of post cure time and temperature on the properties of two phenolic-fiber composites

NASA Technical Reports Server (NTRS)

Lucy, M. H.; Price, H. L.

1975-01-01

Some effects of post-cure time and temperature on the physicomechanical properties of a phenolic-asbestos and a phenolic-glass composite are studied. The molding and post-curing procedures are discussed along with physical and mechanical test results. It is found that the specific gravity of the panels tested decreased slightly but the hardness always increased with post cure, and that the mechanical properties had different patterns of response to increasing post-cure time and temperature. For tensile properties, strength decreased, modulus increased, and elongation at break exhibited little change. In general, the phenolic-asbestos showed more positive response to post cure than did the phenolic-glass. Mold venting is found to impart better properties to the composites concerned.

Solar Eclipse Effect on Shelter Air Temperature

NASA Technical Reports Server (NTRS)

Segal, M.; Turner, R. W.; Prusa, J.; Bitzer, R. J.; Finley, S. V.

1996-01-01

Decreases in shelter temperature during eclipse events were quantified on the basis of observations, numerical model simulations, and complementary conceptual evaluations. Observations for the annular eclipse on 10 May 1994 over the United States are presented, and these provide insights into the temporal and spatial changes in the shelter temperature. The observations indicated near-surface temperature drops of as much as 6 C. Numerical model simulations for this eclipse event, which provide a complementary evaluation of the spatial and temporal patterns of the temperature drops, predict similar decreases. Interrelationships between the temperature drop, degree of solar irradiance reduction, and timing of the peak eclipse are also evaluated for late spring, summer, and winter sun conditions. These simulations suggest that for total eclipses the drops in shelter temperature in midlatitudes can be as high as 7 C for a spring morning eclipse.

Low Temperature Mechanical Testing of Carbon-Fiber/Epoxy-Resin Composite Materials

NASA Technical Reports Server (NTRS)

Nettles, Alan T.; Biss, Emily J.

1996-01-01

The use of cryogenic fuels (liquid oxygen and liquid hydrogen) in current space transportation vehicles, in combination with the proposed use of composite materials in such applications, requires an understanding of how such materials behave at cryogenic temperatures. In this investigation, tensile intralaminar shear tests were performed at room, dry ice, and liquid nitrogen temperatures to evaluate the effect of temperature on the mechanical response of the IM7/8551-7 carbon-fiber/epoxy-resin system. Quasi-isotropic lay-ups were also tested to represent a more realistic lay-up. It was found that the matrix became both increasingly resistant to microcracking and stiffer with decreasing temperature. A marginal increase in matrix shear strength with decreasing temperature was also observed. Temperature did not appear to affect the integrity of the fiber-matrix bond.

Photomicrographic Investigation of Spontaneous Freezing Temperatures of Supercooled Water Droplets

NASA Technical Reports Server (NTRS)

Dorsch, R. G.; Hacker, P. T.

1950-01-01

A photomicrographic technique for investigating eupercooled. water droplets has been devised and. used. to determine the spontaneous freezing temperatures of eupercooled. water droplets of the size ordinarily found. in the atmosphere. The freezing temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous freezing temperature decreased with decrease in the size of the droplets. The effect of size on the spontaneous freezing temperature was particularly marked below 60 microns. Frequency-distribution curves of the spontaneous freezing temperatures observed for droplets of a given size were obtained. Although no droplet froze at a temperature above 20 0 F, all droplets melted at 32 F. Results obtained with a copper support did not differ essentially from those obtained with a platinum surface.

Effects of the thermal discharge from an offshore power plant on plankton and macrobenthic communities in subtropical China.

PubMed

Lin, Jie; Zou, Xinqing; Huang, Faming

2018-06-01

The ecological impact of thermal discharge has become an important issue in the field of marine and environmental protection. We focused on the effects of thermal discharge on seawater temperature and biological communities based on data from before (2006) and after (2013-2014) the construction of a power plant. The thermal discharge induced stratification, which resulted in changes in the vertical hydrodynamic conditions. Stratification combined with elevated temperatures significantly affected the phytoplankton abundance and community structure. Elevated seawater temperatures decreased the chlorophyll-a concentrations by 34% and 63%, at the surface and bottom, respectively. The elevated seawater temperature at the bottom might not be high enough to significantly affect the macrobenthos, but significantly affected the phytoplankton and zooplankton communities. Because these communities serve as food for the macrobenthic community, their changes resulted in growth of the macrobenthos. Furthermore, this effect induced macrobenthic community succession, resulting in decreased species diversity and increased dominance. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrical transport properties in Fe-Cr nanocluster-assembled granular films

NASA Astrophysics Data System (ADS)

Wang, Xiong-Zhi; Wang, Lai-Sen; Zhang, Qin-Fu; Liu, Xiang; Xie, Jia; Su, A.-Mei; Zheng, Hong-Fei; Peng, Dong-Liang

2017-09-01

The Fe100-xCrx nanocluster-assembled granular films with Cr atomic fraction (x) ranging from 0 to 100 were fabricated by using a plasma-gas-condensation cluster deposition system. The TEM characterization revealed that the uniform Fe clusters were coated with a Cr layer to form a Fe-Cr core-shell structure. Then, the as-prepared Fe100-xCrx nanoclusters were randomly assembled into a granular film in vacuum environments with increasing the deposition time. Because of the competition between interfacial resistance and shunting effect of Cr layer, the room temperature resistivity of the Fe100-xCrx nanocluster-assembled granular films first increased and then decreased with increasing the Cr atomic fraction (x), and revealed a maximum of 2 × 104 μΩ cm at x = 26 at.%. The temperature-dependent longitudinal resistivity (ρxx), magnetoresistance (MR) effect and anomalous Hall effect (AHE) of these Fe100-xCrx nanocluster-assembled granular films were also studied systematically. As the x increased from 0 to 100, the ρxx of all samples firstly decreased and then increased with increasing the measuring temperature. The dependence of ρxx on temperature could be well addressed by a mechanism incorporated for the fluctuation-induced-tunneling (FIT) conduction process and temperature-dependent scattering effect. It was found that the anomalous Hall effect (AHE) had no legible scaling relation in Fe100-xCrx nanocluster-assembled granular films. However, after deducting the contribution of tunneling effect, the scaling relation was unambiguous. Additionally, the Fe100-xCrx nanocluster-assembled granular films revealed a small negative magnetoresistance (MR), which decreased with the increase of x. The detailed physical mechanism of the electrical transport properties in these Fe100-xCrx nanocluster-assembled granular films was also studied.

The acute effects of outdoor temperature on blood pressure in a panel of elderly hypertensive patients

NASA Astrophysics Data System (ADS)

Chen, Renjie; Lu, Jianxiong; Yu, Qun; Peng, Li; Yang, Dandan; Wang, Cuicui; Kan, Haidong

2015-12-01

Higher level of blood pressure (BP) in winter than in summer has been observed, but the association between temperature and BP and its potential modifiers with adjustment of individual confounders and time trends was rarely explored. We aimed to investigate the association between outdoor temperature and BP and its potential modification factors in a longitudinal panel study in Shanghai, China. From January 2011 to December 2012, we scheduled 54 follow-ups for BP measurements per subject via home visit every other week for 50 elderly hypertensive patients. We applied linear mixed-effect models to analyze the association between temperature and BP after controlling for individual characteristics, antihypertensive medication, comorbidities, and time trends. We evaluated the potential effect modifiers by stratification analyses. For a 1 °C decrease in the average temperature on concurrent day and previous day, systolic BP increased by 0.19 mmHg (95 % confidence interval = 0.06, 0.31) and diastolic BP increased by 0.12 mmHg (95 % confidence interval = 0.03, 0.21). The effect of temperature on BP was stronger among those with older age, female sex, low socioeconomic status, and obese physique. The effect was weak and even null for those taking the angiotensin receptor blockers, angiotensin-converting enzyme inhibitor, or its combination with calcium antagonists. Further, the effect was almost restricted within those having chronic comorbidities. Our results demonstrated that an acute decrease in outdoor temperature was significantly associated with a rise in BP among elderly hypertensive patients, in Shanghai, China. Individual characteristics, antihypertensive medications, and comorbidities may modify this effect.

Effect of incubation temperature on the self-assembly of regenerated silk fibroin: a study using AFM.

PubMed

Zhong, Jian; Liu, Xunwei; Wei, Daixu; Yan, Juan; Wang, Ping; Sun, Gang; He, Dannong

2015-05-01

Understanding effect of temperature on the molecular self-assembly process will be helpful to unravel the structure-function relationship of biomolecule and to provide important information for the bottom-up approach to nanotechnology. In this work, the effect of incubation temperature on the secondary structures and morphological structures of regenerated silk fibroin (RSF) was systematically studied using atomic force microscopy and Fourier Transform infrared spectroscopy. The effect of incubation temperature on RSF self-assembly was dependent on RSF concentration. For the RSF solution with relatively low concentrations (15 μg/mL and 60 μg/mL), the increase of the incubation temperature mainly accelerated the formation and aggregation of antiparallel β-sheet protofibrils and decreased the formation of random coil protofilaments/globule-like molecules. For the RSF solution with relatively high concentrations (300 μg/mL and 1.5mg/mL), the increase of the incubation temperature mainly accelerated the formation and aggregation of antiparallel β-sheet RSF features (protofibrils and globule-like features) and decreased the formation of random coil bead-like features. This work implies that the morphology and conformation of biomacromolecules could be tuned by controlling the incubation temperature. Further, it will be beneficial to basic understanding of the nanoscale structure formation in different silk-based biomaterials. Copyright © 2015 Elsevier B.V. All rights reserved.

Heat release effects in a turbulent, reacting shear layer

NASA Astrophysics Data System (ADS)

Hermanson, James Carl

The effects of heat release were studied in a planar, gaseous reacting mixing layer formed between free streams containing hydrogen and fluorine in inert diluents. Sufficiently high concentrations of reactants were employed to produce adiabatic flame temperature rises of up to 940 K (1240 K absolute). The Reynolds number at the measuring station, based on velocity difference, 1% temperature thickness and cold kinematic viscosity was approximately 6x10^4. The temperature field was measured with cold wire resistance thermometers and thermocouples. Flow visualization was accomplished by schlieren spark and motion picture photography. Mean velocity information was extracted from mean pitot probe dynamic pressure measurements.Though the displacement thickness of the layer, for zero streamwise pressure gradient, increased with increasing heat release, the actual growth rate of the layer did not increase, but instead decreased slightly. The overall entrainment into the layer was seen to be substantially reduced as a consequence of heat release. Calculations showed that the decrease in layer growth rate can be accounted for by a corresponding reduction in turbulent shear stress.The mean temperature rise profiles, normalized by the adiabatic flame temperature rise, were not greatly changed in shape by heat release. A small decrease in normalized mean temperature rise with heat release was observed. Large scale coherent structures were observed to persist at all levels of heat release in this investigation. The mean structure spacing decreased with increasing temperature. This decrease exceeded the rate of layer growth rate reduction, and suggests that the mechanisms of vortex amalgamation were, to some extent, inhibited by heat release.Imposition of a favorable pressure gradient resulted in additional thinning of the layer, and caused a slight increase in the mixing and amount of chemical product formation. The change in layer growth rate can be shown to be related to a change in free stream velocity ratio induced by pressure gradient.

Effects of temperature and photoperiod on postponing bermudagrass (Cynodon dactylon [L.] Pers.) turf dormancy.

PubMed

Esmaili, Somayeh; Salehi, Hassan

2012-06-15

Growth chamber and field experiments were carried out to determine the effects of extended photoperiod under low and freezing temperatures on bermudagrass turf dormancy at Bajgah, in the southern part of Iran. The experiment in the growth chamber was conducted with four temperature regimes (15, 7.5, 0 and -7.5°C) and three light durations (8, 12 and 16h) in a completely randomized design with four replications. The field study was conducted in two consecutive years (2008-2009) with three light durations (8, 12 and 16h) in months with natural short day length and arranged in a randomized complete blocks design with three replications. Results in both experiments showed that decreasing temperature and photoperiod decreased verdure fresh and dry weight, shoot height, tiller density, leaf area and chlorophyll and relative water contents (RWC). However, rooting depth and fresh weight of roots increased in the growth chamber. Decreasing the temperature and light duration increased electrolyte leakage and proline content. Reducing sugars increased with decreasing temperature and declined with lowering light duration in both shoots and roots. Starch content of both shoots and roots showed an adverse trend compared to reducing sugars; starch content increased in both shoots and roots in all treatments by shortening the photoperiod. Practically, the problem of bermudagrass turf's dormancy could be solved via increasing the photoperiod in months with short day lengths. This treatment would be efficient and useful for turfgrass managers to apply in landscapes and stadiums. Copyright © 2012 Elsevier GmbH. All rights reserved.

Sensitivity of Photosynthesis in a C4 Plant, Maize, to Heat Stress

PubMed Central

Crafts-Brandner, Steven J.; Salvucci, Michael E.

2002-01-01

Our objective was to determine the sensitivity of components of the photosynthetic apparatus of maize (Zea mays), a C4 plant, to high temperature stress. Net photosynthesis (Pn) was inhibited at leaf temperatures above 38°C, and the inhibition was much more severe when the temperature was increased rapidly rather than gradually. Transpiration rate increased progressively with leaf temperature, indicating that inhibition was not associated with stomatal closure. Nonphotochemical fluorescence quenching (qN) increased at leaf temperatures above 30°C, indicating increased thylakoid energization even at temperatures that did not inhibit Pn. Compared with CO2 assimilation, the maximum quantum yield of photosystem II (Fv/Fm) was relatively insensitive to leaf temperatures up to 45°C. The activation state of phosphoenolpyruvate carboxylase decreased marginally at leaf temperatures above 40°C, and the activity of pyruvate phosphate dikinase was insensitive to temperature up to 45°C. The activation state of Rubisco decreased at temperatures exceeding 32.5°C, with nearly complete inactivation at 45°C. Levels of 3-phosphoglyceric acid and ribulose-1,5-bisphosphate decreased and increased, respectively, as leaf temperature increased, consistent with the decrease in Rubisco activation. When leaf temperature was increased gradually, Rubisco activation acclimated in a similar manner as Pn, and acclimation was associated with the expression of a new activase polypeptide. Rates of Pn calculated solely from the kinetics of Rubisco were remarkably similar to measured rates if the calculation included adjustment for temperature effects on Rubisco activation. We conclude that inactivation of Rubisco was the primary constraint on the rate of Pn of maize leaves as leaf temperature increased above 30°C. PMID:12177490

Effect of temperature and air velocity on drying kinetics, antioxidant capacity, total phenolic content, colour, texture and microstructure of apple (var. Granny Smith) slices.

PubMed

Vega-Gálvez, Antonio; Ah-Hen, Kong; Chacana, Marcelo; Vergara, Judith; Martínez-Monzó, Javier; García-Segovia, Purificación; Lemus-Mondaca, Roberto; Di Scala, Karina

2012-05-01

The aim of this work was to study the effect of temperature and air velocity on the drying kinetics and quality attributes of apple (var. Granny Smith) slices during drying. Experiments were conducted at 40, 60 and 80°C, as well as at air velocities of 0.5, 1.0 and 1.5ms(-1). Effective moisture diffusivity increased with temperature and air velocity, reaching a value of 15.30×10(-9)m(2)s(-1) at maximum temperature and air velocity under study. The rehydration ratio changed with varying both air velocity and temperature indicating tissue damage due to processing. The colour difference, ΔE, showed the best results at 80°C. The DPPH-radical scavenging activity at 40°C and 0.5ms(-1) showed the highest antioxidant activity, closest to that of the fresh sample. Although ΔE decreased with temperature, antioxidant activity barely varied and even increased at high air velocities, revealing an antioxidant capacity of the browning products. The total phenolics decreased with temperature, but at high air velocity retardation of thermal degradation was observed. Firmness was also determined and explained using glass transition concept and microstructure analysis. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of salinity, pH and temperature on the re-establishment of bioluminescence and copper or SDS toxicity in the marine dinoflagellate Pyrocystis lunula using bioluminescence as an endpoint

USGS Publications Warehouse

Craig, J.M.; Klerks, P.L.; Heimann, K.; Waits, J.L.

2003-01-01

Pyrocystis lunula is a unicellular, marine, photoautotrophic, bioluminescent dinoflagellate. This organism is used in the Lumitox ?? bioassay with inhibition of bioluminescence re-establishment as the endpoint. Experiments determined if acute changes in pH, salinity, or temperature had an effect on the organisms' ability to re-establish bioluminescence, or on the bioassay's potential to detect sodium dodecyl sulfate (SDS) and copper toxicity. The re-establishment of bioluminescence itself was not very sensitive to changes in pH within the pH 6-10 range, though reducing pH from 8 to levels below 6 decreased this capacity. Increasing the pH had little effect on Cu or SDS toxicity, but decreasing the pH below 7 virtually eliminated the toxicity of either compound in the bioassay. Lowering the salinity from 33 to 27??? or less resulted in a substantial decrease in re-establishment of bioluminescence, while increasing the salinity to 43 or 48 ??? resulted in a small decline. Salinity had little influence on the bioassay's quantification of Cu toxicity, while the data showed a weak negative relationship between SDS toxicity and salinity. Re-establishment of bioluminescence showed a direct dependence on temperature, but only at 10??C did temperature have an obvious effect on the toxicity of Cu in this bioassay. ?? 2003 Elsevier Science Ltd. All rights reserved.

Beneficial effects of footbaths in controlling spasticity after stroke

NASA Astrophysics Data System (ADS)

Matsumoto, Shuji; Shimodozono, Megumi; Etoh, Seiji; Shimozono, Yurika; Tanaka, Nobuyuki; Kawahira, Kazumi

2010-07-01

Footbaths are considered to provide beneficial thermal therapy for post-stroke patients with spasticity, but their anti-spastic effects have not been investigated comprehensively. The present study aimed to evaluate alterations in motor-neuron excitability using F-wave parameters in post-stroke patients with spastic hemiplegia. Subjects’ legs below the knee joint were immersed in water at 41°C and F-wave recordings were made over the abductor hallucis muscle before, immediately after, and 30 min after thermal treatment. Antidromic stimulation was performed on the tibial nerve at the ankle. Measurements included F-wave amplitude, F-wave/M-response ratio, changes in modified Ashworth scale (MAS), body temperature and surface-skin temperature. The mean values of both F-wave parameters were higher on the affected side before footbath treatment. In post-stroke patients, the mean values of F-wave parameters were significantly reduced after footbath treatment ( P < 0.01). The anti-spastic effects of footbath treatment were indicated by decreased F-wave parameters, in parallel with decreases in MAS. Body temperature was significantly increased both immediately after, and 30 min following footbath treatment in both groups, which appeared to play an important role in decreased spasticity. Surface-skin temperature increased immediately after footbath treatment in both groups and returned to baseline 30 min later. These findings demonstrate that the use of footbaths is an effective nonpharmacological anti-spastic treatment that might facilitate stroke rehabilitation.

Ionization competition effects on population distribution and radiative opacity of mixture plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yongjun; Gao, Cheng; Tian, Qinyun

2015-11-15

Ionization competition arising from the electronic shell structures of various atomic species in the mixture plasmas was investigated, taking SiO{sub 2} as an example. Using a detailed-level-accounting approximation, we studied the competition effects on the charge state population distribution and spectrally resolved and Planck and Rosseland mean radiative opacities of mixture plasmas. A set of coupled equations for ionization equilibria that include all components of the mixture plasmas are solved to determine the population distributions. For a given plasma density, competition effects are found at three distinct temperature ranges, corresponding to the ionization of M-, L-, and K-shell electrons ofmore » Si. Taking the effects into account, the spectrally resolved and Planck and Rosseland mean opacities are systematically investigated over a wide range of plasma densities and temperatures. For a given mass density, the Rosseland mean decreases monotonically with plasma temperature, whereas Planck mean does not. Although the overall trend is a decrease, the Planck mean increases over a finite intermediate temperature regime. A comparison with the available experimental and theoretical results is made.« less

Climate and land cover effects on the temperature of Puget Sound streams: Assessment of Climate and Land Use Impacts on Stream Temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Qian; Sun, Ning; Yearsley, John

We apply an integrated hydrology-stream temperature modeling system, DHSVM-RBM, to examine the response of the temperature of the major streams draining to Puget Sound to land cover and climate change. We first show that the model construct is able to reconstruct observed historic streamflow and stream temperature variations at a range of time scales. We then explore the relative effect of projected future climate and land cover change, including riparian vegetation, on streamflow and stream temperature. Streamflow in summer is likely to decrease as the climate warms especially in snowmelt-dominated and transient river basins despite increased streamflow in their lowermore » reaches associated with urbanization. Changes in streamflow also result from changes in land cover, and changes in stream shading result from changes in riparian vegetation, both of which influence stream temperature. However, we find that the effect of riparian vegetation changes on stream temperature is much greater than land cover change over the entire basin especially during summer low flow periods. Furthermore, while future projected precipitation change will have relatively modest effects on stream temperature, projected future air temperature increases will result in substantial increases in stream temperature especially in summer. These summer stream temperature increases will be associated both with increasing air temperature, and projected decreases in low flows. We find that restoration of riparian vegetation could mitigate much of the projected summer stream temperature increases. We also explore the contribution of riverine thermal loadings to the heat balance of Puget Sound, and find that the riverine contribution is greatest in winter, when streams account for up to 1/8 of total thermal inputs (averaged from December through February), with larger effects in some sub-basins. We project that the riverine impact on thermal inputs to Puget Sound will become greater with both urbanization and climate change in winter but become smaller in summer due to climate change.« less

NiMnGa/Si Shape Memory Bimorph Nanoactuation

NASA Astrophysics Data System (ADS)

Lambrecht, Franziska; Lay, Christian; Aseguinolaza, Iván R.; Chernenko, Volodymyr; Kohl, Manfred

2016-12-01

The size dependences of thermal bimorph and shape memory effect of nanoscale shape memory alloy (SMA)/Si bimorph actuators are investigated in situ in a scanning electron microscope and by finite element simulations. By combining silicon nanomachining and magnetron sputtering, freestanding NiMnGa/Si bimorph cantilever structures with film/substrate thickness of 200/250 nm and decreasing lateral dimensions are fabricated. Electrical resistance and mechanical beam bending tests upon direct Joule heating demonstrate martensitic phase transformation and reversible thermal bimorph effect, respectively. Corresponding characteristics are strongly affected by the large temperature gradient in the order of 50 K/µm forming along the nano bimorph cantilever upon electro-thermal actuation, which, in addition, depends on the size-dependent heat conductivity in the Si nano layer. Furthermore, the martensitic transformation temperatures show a size-dependent decrease by about 40 K for decreasing lateral dimensions down to 200 nm. The effects of heating temperature and stress distribution on the nanoactuation performance are analyzed by finite element simulations revealing thickness ratio of SMA/Si of 90/250 nm to achieve an optimum SME. Differential thermal expansion and thermo-elastic effects are discriminated by comparative measurements and simulations on Ni/Si bimorph reference actuators.

Nutrient enrichment modifies temperature-biodiversity relationships in large-scale field experiments

PubMed Central

Wang, Jianjun; Pan, Feiyan; Soininen, Janne; Heino, Jani; Shen, Ji

2016-01-01

Climate effects and human impacts, that is, nutrient enrichment, simultaneously drive spatial biodiversity patterns. However, there is little consensus about their independent effects on biodiversity. Here we manipulate nutrient enrichment in aquatic microcosms in subtropical and subarctic regions (China and Norway, respectively) to show clear segregation of bacterial species along temperature gradients, and decreasing alpha and gamma diversity toward higher nutrients. The temperature dependence of species richness is greatest at extreme nutrient levels, whereas the nutrient dependence of species richness is strongest at intermediate temperatures. For species turnover rates, temperature effects are strongest at intermediate and two extreme ends of nutrient gradients in subtropical and subarctic regions, respectively. Species turnover rates caused by nutrients do not increase toward higher temperatures. These findings illustrate direct effects of temperature and nutrients on biodiversity, and indirect effects via primary productivity, thus providing insights into how nutrient enrichment could alter biodiversity under future climate scenarios. PMID:28000677

Nutrient enrichment modifies temperature-biodiversity relationships in large-scale field experiments.

PubMed

Wang, Jianjun; Pan, Feiyan; Soininen, Janne; Heino, Jani; Shen, Ji

2016-12-21

Climate effects and human impacts, that is, nutrient enrichment, simultaneously drive spatial biodiversity patterns. However, there is little consensus about their independent effects on biodiversity. Here we manipulate nutrient enrichment in aquatic microcosms in subtropical and subarctic regions (China and Norway, respectively) to show clear segregation of bacterial species along temperature gradients, and decreasing alpha and gamma diversity toward higher nutrients. The temperature dependence of species richness is greatest at extreme nutrient levels, whereas the nutrient dependence of species richness is strongest at intermediate temperatures. For species turnover rates, temperature effects are strongest at intermediate and two extreme ends of nutrient gradients in subtropical and subarctic regions, respectively. Species turnover rates caused by nutrients do not increase toward higher temperatures. These findings illustrate direct effects of temperature and nutrients on biodiversity, and indirect effects via primary productivity, thus providing insights into how nutrient enrichment could alter biodiversity under future climate scenarios.

Nutrient enrichment modifies temperature-biodiversity relationships in large-scale field experiments

NASA Astrophysics Data System (ADS)

Wang, Jianjun; Pan, Feiyan; Soininen, Janne; Heino, Jani; Shen, Ji

2016-12-01

Climate effects and human impacts, that is, nutrient enrichment, simultaneously drive spatial biodiversity patterns. However, there is little consensus about their independent effects on biodiversity. Here we manipulate nutrient enrichment in aquatic microcosms in subtropical and subarctic regions (China and Norway, respectively) to show clear segregation of bacterial species along temperature gradients, and decreasing alpha and gamma diversity toward higher nutrients. The temperature dependence of species richness is greatest at extreme nutrient levels, whereas the nutrient dependence of species richness is strongest at intermediate temperatures. For species turnover rates, temperature effects are strongest at intermediate and two extreme ends of nutrient gradients in subtropical and subarctic regions, respectively. Species turnover rates caused by nutrients do not increase toward higher temperatures. These findings illustrate direct effects of temperature and nutrients on biodiversity, and indirect effects via primary productivity, thus providing insights into how nutrient enrichment could alter biodiversity under future climate scenarios.

The effects of temperature treatment on photosynthesis of pitch pine from northern and southern latitudes

Treesearch

F. Thomas Ledig; Joseph G. Clark; Allen P. Drew

1977-01-01

Pitch pine (Pinus rigida Mill.) seedlings were grown at constant temperatures of either 21 C or 29 C. Photosynthetic temperature and light response curves were determined after 59, 107, and 153 days. Rates of Co2 uptake decreased with age, and the response to changes in light and temperature became less pronounced. Growth...

Decreased precision contributes to the hypoxic thermoregulatory response in lizards.

PubMed

Cadena, Viviana; Tattersall, Glenn J

2009-01-01

The decrease in body temperature (T(b)) observed in most vertebrate classes in response to hypoxia has been attributed to a regulated decrease in set-point, protecting organs against tissue death due to oxygen depletion. Hypoxia, however, imparts particular challenges to metabolic function which may, in turn, affect thermoregulation. In ectotherms, where thermoregulation is mainly behavioural, stressors that influence the propensity to move and respond to temperature gradients are expected to have an impact on thermoregulatory control. Using low oxygen as a potent stressor, we evaluated the variability and level of thermoregulation of inland bearded dragons. To examine the source of thermoregulatory variability, we studied their behaviour in an electronically controlled temperature-choice shuttle box, a constant temperature dual-choice shuttle box, and a linear thermal gradient. A significant increase in the size of the T(b) range was observed at the lowest oxygen concentration (4% O(2)), reflecting a decrease in thermoregulatory precision in the temperature-choice shuttle box. This was also accompanied by a drop of approximately 2-4 degrees C in T(b), the drop being greatest in situations where T(b) must be actively defended. Situations that force the lizards to continually choose temperatures, rather than passively remain at a given temperature, lead to an increase in the variability in the manifested T(b), which is further exaggerated in hypoxia. This study reveals that a decrease in thermoregulatory precision caused by a diminished propensity to move or effect appropriate thermoregulatory responses may be a contributing component in the lowering of selected body temperatures observed in many hypoxic ectotherms.

Cold Blooded: Evaluating Brain Temperature by MRI During Surface Cooling of Human Subjects.

PubMed

Curran, Eric J; Wolfson, Daniel L; Watts, Richard; Freeman, Kalev

2017-10-01

Targeted temperature management (TTM) confers neurological and survival benefits for post-cardiac arrest patients with return of spontaneous circulation (ROSC) who remain comatose. Specialized equipment for induction of hypothermia is not available in the prehospital setting, and there are no reliable methods for emergency medical services personnel to initiate TTM. We hypothesized that the application of surface cooling elements to the neck will decrease brain temperature and act as initiators of TTM. Magnetic resonance (MR) spectroscopy was used to evaluate the effect of a carotid surface cooling element on brain temperature in healthy adults. Six individuals completed this study. We measured a temperature drop of 0.69 ± 0.38 °C (95% CI) in the cortex of the brain following the application of the cooling element. Application of a room temperature element also caused a measurable decrease in brain temperature of 0.66 ± 0.41 °C (95% CI) which may be attributable to baroreceptor activation. The application of surface cooling elements to the neck decreased brain temperature and may serve as a method to initiate TTM in the prehospital setting.

A novel approach to determine the effect of irrigation on temperature and failure of Ni-Ti endodontic rotary files

PubMed Central

Mousavi, Sayed Ali; Kargar-Dehnavi, Vida; Mousavi, Sayed Amir

2012-01-01

Background: Nickel-titanium (Ni-Ti) rotary instrument files are important devices in Endodontics in root canal preparation. Ni-Ti file breakage is a critical and problematic issue and irrigation techniques were applied to decrease risk of file failure root. The aim of the present study was to compare the temperature gradient change of different irrigation solutions with Ni-Ti rotary instrument system during root canal preparation and also to define their effects on the file failure. Materials and Methods: A novel computerized instrumentation was utilized and thirty standard (ProFile #25/.04) files were divided into three groups and subjected to a filing in the root canal test. Changes in temperature on teeth under constant instrumental conditions with custom-designed computerized experimental apparatus were measured by using a temperature sensor bonded to the apical hole. A rotary instrument for canal preparation in three series of solution was used and the changes in temperature after each solution were compared. Finally, the file failure results were mentored according to each step of test. Comparisons were performed between group status clinically by using ANOVA (t) test, once the sample showed up normal and differences of P<0.01 were considered significant. All data collected were computerized and analyzed for frequency, distribution, and statistical description. Results: There was a decrease in the temperature of the instruments, which were immersed in 5% NaOCl, when compared with the water group (P<0.01). There was also a decrease in the temperature of the instruments immersed in water, when compared with the no solution group (P<0.01). Test results showed that sodium hypochlorite, water, or air of root canals does alter the properties of gradual temperature change and contributes to the failure of the instruments. Conclusion: By immersing the file in 5% NaOCl, the temperature gradient decreased and instrument failure was reduced. PMID:23087732

Effects of elevated water temperature on physiological responses in adult freshwater mussels

USGS Publications Warehouse

Ganser, Alissa M.; Newton, Teresa J.; Haro, Roger J.

2015-01-01

These data suggest that elevated temperatures can alter metabolic rates in native mussels and may decrease the amount of energy that is available for key biological processes, such as survival, growth and reproduction.

Transport, Optical, and Magnetic Properties of the Conducting Halide Perovskite CH 3NH 3SnI 3

NASA Astrophysics Data System (ADS)

Mitzi, D. B.; Feild, C. A.; Schlesinger, Z.; Laibowitz, R. B.

1995-01-01

A low-temperature ( T ≤ 100°C) solution technique is described for the preparation of polycrystalline and single crystal samples of the conducting halide perovskite, CH 3NH 3SnI 3. Transport, Hall effect, magnetic, and optical properties are examined over the temperature range 1.8-300 K, confirming that this unusual conducting halide perovskite is a low carrier density p-type metal with a Hall hole density, 1/ RHe ≃ 2 × 10 19 cm -3. The resistivity of pressed pellet samples decreases with decreasing temperature with resistivity ratio ρ(300 K)/ρ(2 K) ≃ 3 and room temperature resistivity ρ(300 K) ≃ 7 mΩ-cm. A free-carrier infrared reflectivity spectrum with a plasma edge observed at approximately 1600 cm -1 further attests to the metallic nature of this compound and suggests a small optical effective mass, m* ≃ 0.2.

Magnetic and magnetocaloric properties of Ni-Mn-Cr-Sn Heusler alloys under the effects of hydrostatic pressure

NASA Astrophysics Data System (ADS)

Pandey, Sudip; Us Saleheen, Ahmad; Quetz, Abdiel; Chen, Jing-Han; Aryal, Anil; Dubenko, Igor; Stadler, Shane; Ali, Naushad

2018-05-01

The magnetic, thermal, and magnetocaloric properties of Ni45Mn43CrSn11 Heusler alloy have been investigated using differential scanning calorimetry and magnetization with hydrostatic pressure measurements. A shift in the martensitic transition temperature (TM) to higher temperatures was observed with the application of pressure. The application of pressure stabilizes the martensitic state and demonstrated that pressure can be a parameter used to control and tune the martensitic transition temperature (the temperature where the largest magnetocaloric effect is observed). The magnetic entropy change significantly decreases from 33 J/kg K to 16 J/kg K under the application of a hydrostatic pressure of 0.95 GPa. The critical field of the direct metamagnetic transition increases, whereas the initial susceptibility (dM/dH) in the low magnetic field region drastically decreases with increasing pressure. The relevant parameters that affect the magnetocaloric properties are discussed.

Investigation of Temperature Ratio Effect on the Low-Frequency Acoustic Spectra of Heated Jets

NASA Astrophysics Data System (ADS)

Karam, Sofia

Jet noise remains one of the most important problems in the aviation industry, and its reduction is sought in the context of both commercial and military aircraft. In this thesis, an investigation of the jet noise is conducted in terms of the effect of temperature and Mach number on low frequency acoustic spectra. A low-order model derived from the generalized acoustic analogy method via a low-frequency asymptotic approach is utilized, where the mean flow and pertinent statistical quantities are obtained from RANS simulations. The study involves a combination of seven acoustic Mach numbers ranging from 0.3 to 1.5 and five temperature ratios (TR) ranging from 1 to 3. The model is calibrated with existing experimental measurements of a Mach 0.9 and TR = 1 jet. The results show that the sound pressure level increases with the increase in Mach number, and decreases with the decrease in temperature ratios.

Effect of Vacuum Frying on Changes in Quality Attributes of Jackfruit (Artocarpus heterophyllus) Bulb Slices.

PubMed

Maity, Tanushree; Bawa, A S; Raju, P S

2014-01-01

The effect of frying temperatures and durations on the quality of vacuum fried jackfruit (JF) chips was evaluated. Moisture content and breaking force of JF chips decreased with increase in frying temperature and time during vacuum frying whereas the oil content increased. The frying time for JF chips was found to be 30, 25, and 20 minutes at 80, 90, and 100°C, respectively. JF chips fried at higher temperature resulted in maximum shrinkage (48%). The lightness in terms of hunter L (*) value decreased significantly (P < 0.05) during frying. Sensory evaluation showed maximum acceptability for JF chips fried at 90°C for 25 min. Frying under vacuum at lower temperatures was found to retain bioactive compounds such as total phenolics, total flavonoids, and total carotenoids in JF chips. Almost 90% of carotenoids were lost from the samples after 30 min of frying at 100°C.

Hall effect of copper nitride thin films

NASA Astrophysics Data System (ADS)

Yue, G. H.; Liu, J. Z.; Li, M.; Yuan, X. M.; Yan, P. X.; Liu, J. L.

2005-08-01

The Hall effect of copper nitride (Cu3N) thin films was investigated in our work. Cu3N films were deposited on glass substrates by radio-frequency (RF) magnetron sputtering at different temperatures using pure copper as the sputtering target. The Hall coefficients of the films are demonstrated to be dependent on the deposition gas flow rate and the measuring temperature. Both the Hall coefficient and resistance of the Cu3N films increase with the nitrogen gas flow rate at room temperature, while the Hall mobility and the carrier density of the films decrease. As the temperature changed from 100 K to 300 K, the Hall coefficient and the resistivity of the films decreased, while the carrier density increased and Hall mobility shows no great change. The energy band gap of the Cu3N films deduced from the curve of the common logarithm of the Hall coefficient against 1/T is 1.17-1.31 eV.

Annealing effects on electron-beam evaporated Al 2O 3 films

NASA Astrophysics Data System (ADS)

Shuzhen, Shang; Lei, Chen; Haihong, Hou; Kui, Yi; Zhengxiu, Fan; Jianda, Shao

2005-04-01

The effects of post-deposited annealing on structure and optical properties of electron-beam evaporated Al 2O 3 single layers were investigated. The films were annealed in air for 1.5 h at different temperatures from 250 to 400 °C. The optical constants and cut-off wavelength were deduced. Microstructure of the samples was characterized by X-ray diffraction (XRD). Profile and surface roughness measurement instrument was used to determine the rms surface roughness. It was found that the cut-off wavelength shifted to short wavelength as the annealing temperature increased and the total optical loss decreased. The film structure remained amorphous even after annealing at 400 °C temperature and the samples annealed at higher temperature had the higher rms surface roughness. The decreasing total optical loss with annealing temperature was attributed to the reduction of absorption owing to oxidation of the film by annealing. Guidance to reduce the optical loss of excimer laser mirrors was given.

Structural Investigation of Cesium Lead Halide Perovskites for High-Efficiency Quantum Dot Light-Emitting Diodes.

PubMed

Le, Quyet Van; Kim, Jong Beom; Kim, Soo Young; Lee, Byeongdu; Lee, Dong Ryeol

2017-09-07

We have investigated the effect of reaction temperature of hot-injection method on the structural properties of CsPbX 3 (X: Br, I, Cl) perovskite nanocrystals (NCs) using small- and wide-angle X-ray scattering. It is confirmed that the size of the NCs decreased as the reaction temperature decreased, resulting in stronger quantum confinement. The cubic-phase perovskite NCs formed despite the fact that the reaction temperatures increased from 140 to 180 °C; however, monodispersive NC cubes that are required for densely packing self-assembly film were formed only at lower temperatures. From the X-ray scattering measurements, the spin-coated film from more monodispersive perovskite nanocubes synthesized at lower temperatures resulted in more preferred orientation. This dense-packing perovskite film with preferred orientation yielded efficient light-emitting diode (LED) performance. Thus the dense-packing structure of NC assemblies formed after spin-coating should be considered for high-efficient LEDs based on perovskite quantum dots in addition to quantum confinement effect of the quantum dots.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le, Quyet Van; Kim, Jong Beom; Kim, Soo Young

We have investigated the effect of reaction temperature of hot-injection method on the structural properties of CsPbX3 (X: Br, I, Cl) perovskite nanocrystals (NCs) using the small- and wide-angle X-ray scattering. It is confirmed that the size of the NCs decreased as the reaction temperature decreased, resulting stronger quantum confinement. The cubic-phase perovskite NCs were formed despite the reaction temperatures increased from 140 to 180 °C. However, monodispersive NC cubes which are required for densely packing self-assembly film were only formed at lower temperatures. From the X-ray scattering measurements, the spin-coated film from more monodispersive perovskite nanocubes synthesized at lowermore » temperatures resulted in more preferred orientation. This dense-packing perovskite film with preferred orientation yielded efficient light-emitting diode (LED) performance. Thus, the dense-packing structure of NC assemblies formed after spin-coating should be considered for high-efficient LEDs based on perovskite quantum dots in addition to quantum confinement effect of the quantum dots.« less

Ultrasound effects on the degradation kinetics, structure, and antioxidant activity of sea cucumber fucoidan.

PubMed

Guo, Xin; Ye, Xingqian; Sun, Yujing; Wu, Dan; Wu, Nian; Hu, Yaqin; Chen, Shiguo

2014-02-05

The effects of ultrasound on the molecular weight, structure, and antioxidant potential of a fucoidan found in Isostichopus badionotus were investigated. The results showed the molecular weight (Mw) of fucoidan decreased obviously after ultrasound treatment. Higher ultrasonic intensity, lower temperature, and lower fucoidan concentrations led to a more effective sonochemical effect. The kinetic model for fucoidan degradation fitted to 1/M(wt)-1/M(w0) = kt at the tested temperature. The optimized degradation conditions by response surface methodology (RSM) were temperature, 12 °C, and intensity, 508 W/cm². Structural analysis by FTIR and NMR indicated the fucoidan kept the linear tetrasaccharide repeating units as the original polysaccharides after the ultrasound treatment, with only slight destruction of the middle nonsulfated fucose units. Antioxidant activity assay showed the antioxidant activity was slightly improved by the ultrasound treatment. The results suggested that ultrasound treatment is an effective approach to decrease the M(w) of fucoidan with only minor structural destruction.

Heated wire humidification circuit attenuates the decrease of core temperature during general anesthesia in patients undergoing arthroscopic hip surgery.

PubMed

Park, Sooyong; Yoon, Seok-Hwa; Youn, Ann Misun; Song, Seung Hyun; Hwang, Ja Gyung

2017-12-01

Intraoperative hypothermia is common in patients undergoing general anesthesia during arthroscopic hip surgery. In the present study, we assessed the effect of heating and humidifying the airway with a heated wire humidification circuit (HHC) to attenuate the decrease of core temperature and prevent hypothermia in patients undergoing arthroscopic hip surgery under general anesthesia. Fifty-six patients scheduled for arthroscopic hip surgery were randomly assigned to either a control group using a breathing circuit connected with a heat and moisture exchanger (HME) (n = 28) or an HHC group using a heated wire humidification circuit (n = 28). The decrease in core temperature was measured from anesthetic induction and every 15 minutes thereafter using an esophageal stethoscope. Decrease in core temperature from anesthetic induction to 120 minutes after induction was lower in the HHC group (-0.60 ± 0.27℃) compared to the control group (-0.86 ± 0.29℃) (P = 0.001). However, there was no statistically significant difference in the incidence of intraoperative hypothermia or the incidence of shivering in the postanesthetic care unit. The use of HHC may be considered as a method to attenuate intraoperative decrease in core temperature during arthroscopic hip surgery performed under general anesthesia and exceeding 2 hours in duration.

Differential effects of dopamine and opioid receptor blockade on motivated Coca-Cola drinking behavior and associated changes in brain, skin and muscle temperatures.

PubMed

Kiyatkin, E A

2010-05-05

Although pharmacological blockade of both dopamine (DA) and opiate receptors has an inhibiting effect on appetitive motivated behaviors, it is still unclear which physiological mechanisms affected by these treatments underlie the behavioral deficit. To clarify this issue, we examined how pharmacological blockade of either DA (SCH23390+eticlopride at 0.2 mg/kg each) or opioid receptors (naloxone 1 mg/kg) affects motor activity and temperature fluctuations in the nucleus accumbens (NAcc), temporal muscle, and facial skin associated with motivated Coca-Cola drinking behavior in rats. In drug-free conditions, presentation of a cup containing 5 ml of Coca-Cola induced locomotor activation and rapid NAcc temperature increases, which both transiently decreased during drinking, and phasically increased again after the cup was emptied. Muscle temperatures followed this pattern, but increases were weaker and more delayed than those in the NAcc. Skin temperature rapidly dropped after cup presentation, remained at low levels during consumption, and slowly restored during post-consumption behavioral activation. By itself, DA receptor blockade induced robust decrease in spontaneous locomotion, moderate increases in brain and muscle temperatures, and a relative increase in skin temperatures, suggesting metabolic activation coupled with adynamia. Following this treatment (approximately 180 min), motor activation to cup presentation and Coca-Cola consumption were absent, but rats showed NAcc and muscle temperature increases following cup presentation comparable to control. Therefore, DA receptor blockade does not affect significantly central and peripheral autonomic responses to appetitive stimuli, but eliminates their behavior-activating effects, thus disrupting appetitive behavior and blocking consumption. Naloxone alone slightly decreased brain and muscle temperatures and increased skin temperatures, pointing at the enhanced heat loss and possible minor inhibition of basal metabolic activity. This treatment (approximately 60 min) had minimal effects on the latencies of drinking, but increased its total duration, with licking interrupted by pauses and retreats. This behavioral attenuation was coupled with weaker than in control locomotor activation and diminished temperature fluctuations in each recording location. Therefore, attenuation of normal behavioral and physiological responses to appetitive stimuli appears to underlie modest inhibiting effects of opiate receptor blockade on motivated behavior and consumption. (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Silica-promoted Diels-Alder reactions in carbon dioxide from gaseous to supercritical conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinstein, R.D.; Renslo, A.R.; Danheiser, R.L.

1999-04-15

Amorphous fumed silica (SiO{sub 2}) was shown to increase yields and selectivities of several Diels-Alder reactions in gaseous and supercritical CO{sub 2}. Pressure effects on the Diels-Alder reaction were explored using methyl vinyl ketone and penta-1,3-diene at 80 C. The selectivity of the reaction was not affected by pressure/density. As pressure was increased, the yield decreased. At the reaction temperature, adsorption isotherms at various pressures were obtained for the reactants and the Diels-Alder adduct. As expected when pressure is increased, the ratio of the amount of reactants adsorbed to the amount of reactants in the fluid phase decreases, thus causingmore » the yield to decrease. The Langmuir adsorption model fit the adsorption data. The Langmuir equilibrium partitioning constants all decreased with increasing pressure. The effect of temperature on adsorption was experimentally determined and traditional heats of adsorption were calculated. However, since supercritical CO{sub 2} is a highly compressible fluid, it is logical to examine the effect of temperature at constant density. In this case, entropies of adsorption were obtained. The thermodynamic properties that influence the real enthalpy and entropy of adsorption were derived. Methods of doping the silica and improving yields and selectivities were also explored.« less

Effect of water temperature on diuresis-natriuresis: AVP, ANP, and urodilatin during immersion in men

NASA Technical Reports Server (NTRS)

Nakamitsu, S.; Sagawa, S.; Miki, K.; Wada, F.; Nagaya, K.; Keil, L. C.; Drummer, C.; Gerzer, R.; Greenleaf, J. E.; Hong, S. K.

1994-01-01

Effects of water temperature on diuresis, natriuresis, and associated endocrine responses during head-out immersion were studied in eight men during four 5-h experimental conditions: air control at 28 C and immersion at 34.5 C (thermoneutral (Tnt)), 36 C (above Tnt (aTnt)), and 32 C (below Tnt (bTnt). Esophageal temperature decreased by approximately 0.4 C in bTnt and increased by approximately 0.5 C in aTnt. Cardiac output increased by approximately 80% in aTnt and approximately 40% in bTnt while thoracic impedance, an index of central blood pooling, decreased by 7.5 ohms in bTnt (NS vs. Tnt) and 8.8 ohms in aTnt. Total peripheral resistance decreased at all temperatures (50% in aTnt, 20% in bTnt). Urine flow and Na(+) excretion increased by sixfold in bTnt and Tnt but by only threefold in aTnt. Creatinine clearance was unchanged while osmolal clearance (but not free water clearance) increased two-fold with all immersions. Plasma atrial natriuretic peptide (ANP), urinary urodilatin, and urinary guanosine 3',5'-cyclic monophosphate increased while plasma renin activity, aldosterone, and arginine vasopressin (AVP) decreased similarly at all temperatures. bTnt did not potentiate diuresis by selective attenuation of AVP. The overall natriuretic response exhibited a higher correlation with urodilatin than with ANP. Because diuresis and natriuresis were significantly attenuated in aTnt where central blood pooling was greater, we conclude that mechanisms other than the atrial stretch receptor reflex, i.e., urodilatin and effective arterial blood volume, may play more predominant roles in the mechanism of immersion-induced diuresis and natriuresis.

Food restriction attenuates oxidative stress in brown adipose tissue of striped hamsters acclimated to a warm temperature.

PubMed

Zhang, Ji-Ying; Zhao, Xiao-Ya; Wang, Gui-Ying; Wang, Chun-Ming; Zhao, Zhi-Jun

2016-05-01

It has been suggested that the up-regulation of uncoupling proteins (UCPs) decreases reactive oxygen species (ROS) production, in which case there should be a negative relationship between UCPs expression and ROS levels. In this study, the effects of temperature and food restriction on ROS levels and metabolic rate, UCP1 mRNA expression and antioxidant levels were examined in the brown adipose tissue (BAT) of the striped hamsters (Cricetulus barabensis). The metabolic rate and food intake of hamsters which had been restricted to 80% of ad libitum food intake, and acclimated to a warm temperature (30°C), decreased significantly compared to a control group. Hydrogen peroxide (H2O2) levels were 42.9% lower in food restricted hamsters than in the control. Malonadialdehyde (MDA) levels of hamsters acclimated to 30°C that were fed ad libitum were significantly higher than those of the control group, but 60.1% lower than hamsters that had been acclimated to the same temperature but subject to food restriction. There were significantly positive correlations between H2O2 and, MDA levels, catalase activity, and total antioxidant capacity. Cytochrome c oxidase activity and UCP1 mRNA expression significantly decreased in food restricted hamsters compared to the control. These results suggest that warmer temperatures increase oxidative stress in BAT by causing the down-regulation of UCP1 expression and decreased antioxidant activity, but food restriction may attenuate the effects. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dexamethasone decreases the incidence of shivering after cardiac surgery: a randomized, double-blind, placebo-controlled study.

PubMed

Yared, J P; Starr, N J; Hoffmann-Hogg, L; Bashour, C A; Insler, S R; O'Connor, M; Piedmonte, M; Cosgrove, D M

1998-10-01

Shivering after cardiac surgery is common, and may be a result of intraoperative hypothermia. Another possible etiology is fever and chills secondary to activation of the inflammatory response and release of cytokines by cardiopulmonary bypass. Dexamethasone decreases the gradient between core and skin temperature and modifies the inflammatory response. The goal of this study was to determine whether dexamethasone can reduce the incidence of shivering. Two hundred thirty-six patients scheduled for elective coronary and/or valvular surgery were randomly assigned to receive either dexamethasone 0.6 mg/kg or placebo after the induction of anesthesia. All patients received standard monitoring and anesthetic management. After arrival in the intensive care unit (ICU), nurses unaware of the treatment groups recorded visible shivering, as well as skin and pulmonary artery temperatures. Analysis of shivering rates was performed by using chi2 tests and logistic regression analysis. Compared with placebo, dexamethasone decreased the incidence of shivering (33.0% vs 13.1%; P = 0.001). It was an independent predictor of reduced incidence of shivering and was also associated with a higher skin temperature on ICU admission and a lower central temperature in the early postoperative period. Dexamethasone is effective in decreasing the incidence of shivering. The effectiveness of dexamethasone is independent of temperature and duration of cardiopulmonary bypass. Shivering after cardiac surgery may be part of the febrile response that occurs after release of cytokines during cardiopulmonary bypass.

High temperature fiber sensor using the interference effect within a suspended core microstructured optical fiber

NASA Astrophysics Data System (ADS)

Nguyen, Linh V.; Warren-Smith, Stephen C.; Ebendorff-Heidepriem, Heike; Monro, Tanya M.

2016-04-01

We report a high temperature fiber sensor based on the multimode interference effect within a suspended core microstructured optical fiber (SCF). By splicing a short section of SCF with a lead-in single-mode fiber (SMF), the sensor head was formed. A complex interference pattern was obtained in the reflection spectrum as the result of the multiple excited modes in the SCF. The complexity of the interference indicates that there are more than two dominantly excited modes in the SCF, as resolved by Fast Fourier Transform (FFT) analysis of the interference. The proposed sensor was subjected to temperature variation from 20°C to 1100°C. The fringe of the filtered spectrum red-shifted linearly with respect to temperature varying between 20°C and 1100°C, with similar temperature sensitivity for increasing and decreasing temperature. Phase monitoring was used for an extended temperature experiment (80 hours) in which the sensor was subjected to several different temperature variation conditions namely (i) step-wise increase/decrease with 100°C steps between 20°C and 1100°C, (ii) dwelling overnight at 400°C, (iii) free fall from 1100°C to 132°C, and (iv) continuous increase of temperature from 132°C to 1100°C. Our approach serves as a simple and cost-effective alternative to the better-known high temperature fiber sensors such as the fiber Bragg grating (FBG) in sapphire fibers or regenerated FBG in photosensitive optical fibers.

Theoretical predications of the effects of temperature on simulated adaptive processes in human motor nerve axons at 20°C-42°C.

PubMed

Stephanova, D I; Daskalova, M

2014-09-01

The effects of temperature on conducting and accommodative processes in the myelinated human motor nerve fiber were previously studied by us in the range of 20°C-42°C. To complete the cycle of our studies on adaptive processes in the fiber, the temperature effects on strength-duration time constant, rheobasic current and recovery cycle are investigated. The computations use our temperature dependent multi-layered model of the fiber and the temperature is increased from 20°C to 42°C. The results show that these excitability parameters are more sensitive to the hypothermia (≤ 25°C) and are most sensitive to the hyperthermia (≥ 40°C), especially at 42°C, than at temperatures in the range of 28°C-37°C. With the increase of temperature from 20°C to 42°C, the strength-duration time constant decreases ~ 8.8 times, while it decreases ~ 2.7% per °C in the range of 28°C-37°C. Conversely, the rheobasic current increases ~ 4.4 times from 20°C to 42°C, while it increases ~ 2.3% per °C in the range of 28°C-37°C. The behavior of relative refractory period and axonal superexcitability in a 100 ms recovery cycle is complex with the increase of temperature. The axonal superexcitability decreases with the increase of temperature during hypothermia. However, it increases rapidly with the increase of temperature during hyperthermia, especially at 42°C and a block of each applied third testing stimulus is obtained. The superexcitability period is followed by a late subexcitability period when the temperatures are in the physiological range of 32°C-37°C. The present results are essential for the interpretation of mechanisms of excitability parameter changes obtained here and measured in healthy subjects with symptoms of cooling, warming and fever, which can result from alterations in body temperature. Our present and previous results confirm that 42°C is the highest critical temperature for healthy subjects.

Transport, motility, biofilm forming potential and survival of Bacillus subtilis exposed to cold temperature and freeze-thaw.

PubMed

Asadishad, Bahareh; Olsson, Adam L J; Dusane, Devendra H; Ghoshal, Subhasis; Tufenkji, Nathalie

2014-07-01

In cold climate regions, microorganisms in upper layers of soil are subject to low temperatures and repeated freeze-thaw (FT) conditions during the winter. We studied the effects of cold temperature and FT cycles on the viability and survival strategies (namely motility and biofilm formation) of the common soil bacterium and model pathogen Bacillus subtilis. We also examined the effect of FT on the transport behavior of B. subtilis at two solution ionic strengths (IS: 10 and 100 mM) in quartz sand packed columns. Finally, to study the mechanical properties of the bacteria-surface bond, a quartz crystal microbalance with dissipation monitoring (QCM-D) was used to monitor changes in bond stiffness when B. subtilis attached to a quartz substrate (model sand surface) under different environmental conditions. We observed that increasing the number of FT cycles decreased bacterial viability and that B. subtilis survived for longer time periods in higher IS solution. FT treatment decreased bacterial swimming motility and the transcription of flagellin encoding genes. Although FT exposure had no significant effect on the bacterial growth rate, it substantially decreased B. subtilis biofilm formation and correspondingly decreased the transcription of matrix production genes in higher IS solution. As demonstrated with QCM-D, the bond stiffness between B. subtilis and the quartz surface decreased after FT. Moreover, column transport studies showed higher bacterial retention onto sand grains after exposure to FT. This investigation demonstrates how temperature variations around the freezing point in upper layers of soil can influence key bacterial properties and behavior, including survival and subsequent transport. Copyright © 2014 Elsevier Ltd. All rights reserved.

Warm Ambient Temperature Decreases Food Intake in a Simulated Office Setting: A Pilot Randomized Controlled Trial.

PubMed

Bernhard, Molly C; Li, Peng; Allison, David B; Gohlke, Julia M

2015-01-01

We hypothesized that exposure to temperatures above the thermoneutral zone (TNZ) would decrease food intake in young adults in a sedentary office environment over a 2-h period. Participants wearing standardized clothing were randomized to perform routine office work in the TNZ, considered control (19-20°C), or above the TNZ considered warmer (26-27°C) using a parallel-group design (n = 11 and 9, respectively). Thermal images of the inner canthus of their eye and middle finger nail bed, representing proxies of core and peripheral temperatures, respectively, were taken at baseline, first, and second hour during this lunchtime study. Heat dissipation was estimated using peripheral temperature. General linear models were built to examine the effects of thermal treatment on caloric intake and potential mediation by heat dissipation. Researchers conducted the trial registered as NCT02386891 at Clinicaltrials.gov during April to May 2014. During the 2-h stay in different ambient temperatures, the participants in the control conditions ate 99.5 kcal more than those in the warmer conditions; however, the difference was not statistically significant. Female participants ate about 350 kcal less than the male participants (p = 0.024) in both groups and there was no significant association between caloric intake and participant's body mass index (BMI). After controlling for thermal treatment, gender and BMI, the participant's peripheral temperature was significantly associated with caloric intake (p = 0.002), suggesting a mediating effect. Specifically, for every 1°C increase in peripheral temperature suggesting increased heat dissipation, participants ate 85.9 kcal less food. This pilot study provided preliminary evidence of effects of thermal environment on food intake. It suggests that decreased food intake in the experimental (warmer) environment is potentially mediated through thermoregulatory mechanisms.

The combined influence of sub-optimal temperature and salinity on the in vitro viability of Perkinsus marinus, a protistan parasite of the eastern oyster Crassostrea virginica

USGS Publications Warehouse

La Peyre, M.K.; Casas, S.M.; Gayle, W.; La Peyre, Jerome F.

2010-01-01

Perkinsus marinus is a major cause of mortality in eastern oysters along the Gulf of Mexico and Atlantic coasts. It is also well documented that temperature and salinity are the primary environmental factors affecting P. marinus viability and proliferation. However, little is known about the effects of combined sub-optimal temperatures and salinities on P. marinus viability. This in vitro study examined those effects by acclimating P. marinus at three salinities (7, 15, 25. ppt) to 10 ??C to represent the lowest temperatures generally reached in the Gulf of Mexico, and to 2 ??C to represent the lowest temperatures reached along the mid-Atlantic coasts and by measuring changes in cell viability and density on days 1, 30, 60 and 90 following acclimation. Cell viability and density were also measured in 7. ppt cultures acclimated to each temperature and then transferred to 3.5. ppt. The largest decreases in cell viability occurred only with combined low temperature and salinity, indicating that there is clearly a synergistic effect. The largest decreases in cell viability occurred only with both low temperature and salinity after 30. days (3.5. ppt, 2 ??C: 0% viability), 60. days (3.5. ppt, 10 ??C: 0% viability) and 90. days (7. ppt, 2 ??C: 0.6 ?? 0.7%; 7. ppt, 10 ??C: 0.2 ?? 0.2%). ?? 2010 .

Color changes kinetics during deep fat frying of carrot slice

NASA Astrophysics Data System (ADS)

Salehi, Fakhreddin

2018-05-01

Heat and mass transfer phenomena take place during frying cause physicochemical changes, which affect the colour and surface of the fried products. The effect of frying temperature on the colour changes and heat transfer during deep fat frying of carrot has been investigated. The colour scale parameters redness (a*), yellowness (b*) and lightness (L*), and color change intensity (ΔE) were used to estimate colour changes during frying as a function of oil temperature. L* value of fried carrot decreased during frying. The redness of fried carrot decreased during the early stages of frying, while it increased afterwards (become more red). A first-order kinetic equation was used for each one of the three colour parameters, in which the rate constant is a function of oil temperatures. The results showed that oil temperature has a significant effect on the colour parameters. Different kinetic models were used to fit the experimental data and the results revealed that the quadratic model was the most suitable to describe the color change intensity (ΔE) (R > 0.96). Center temperature of carrot slice increased with increase in oil temperature and time during frying.

Roles of Urban Tree Canopy and Buildings in Urban Heat Island Effects: Parameterization and Preliminary Results

NASA Technical Reports Server (NTRS)

Loughner, Christopher P.; Allen, Dale J.; Zhang, Da-Lin; Pickering, Kenneth E.; Dickerson, Russell R.; Landry, Laura

2012-01-01

Urban heat island (UHI) effects can strengthen heat waves and air pollution episodes. In this study, the dampening impact of urban trees on the UHI during an extreme heat wave in the Washington, D.C., and Baltimore, Maryland, metropolitan area is examined by incorporating trees, soil, and grass into the coupled Weather Research and Forecasting model and an urban canopy model (WRF-UCM). By parameterizing the effects of these natural surfaces alongside roadways and buildings, the modified WRF-UCM is used to investigate how urban trees, soil, and grass dampen the UHI. The modified model was run with 50% tree cover over urban roads and a 10% decrease in the width of urban streets to make space for soil and grass alongside the roads and buildings. Results show that, averaged over all urban areas, the added vegetation decreases surface air temperature in urban street canyons by 4.1 K and road-surface and building-wall temperatures by 15.4 and 8.9 K, respectively, as a result of tree shading and evapotranspiration. These temperature changes propagate downwind and alter the temperature gradient associated with the Chesapeake Bay breeze and, therefore, alter the strength of the bay breeze. The impact of building height on the UHI shows that decreasing commercial building heights by 8 m and residential building heights by 2.5 m results in up to 0.4-K higher daytime surface and near-surface air temperatures because of less building shading and up to 1.2-K lower nighttime temperatures because of less longwave radiative trapping in urban street canyons.

The effect of temperature on basal tension and thyroarytenoid muscle contraction in an isolated rat glottis model.

PubMed

Wang, Hsing-Won; Chu, Yueng-Hsiang; Chao, Pin-Zhir; Lee, Fei-Peng

2014-10-01

The pitch of voice is closely related to the vocal fold tension, which is the end result of coordinated movement of the intralaryngeal muscles, and especially the thyroarytenoid muscle. It is known that vocal quality may be affected by surrounding temperature; however, the effect of temperature on vocal fold tension is mostly unknown. Thus, the aim of this study was to evaluate the effect of temperature on isolated rat glottis and thyroarytenoid muscle contraction induced by electrical field stimulation. In vitro isometric tension of the glottis ring from 30 Sprague-Dawley rats was continuously recorded by the tissue bath method. Electrical field stimulation was applied to the glottis ring with two wire electrodes placed parallel to the glottis and connected to a direct-current stimulator. The tension changes of the rat glottis rings that were either untreated or treated with electrical field stimulation were recorded continuously at temperatures from 37 to 7 °C or from 7 to 37 °C. Warming from 7 to 37 °C increased the basal tension of the glottis rings and decreased the electrical field stimulation-induced glottis ring contraction, which was chiefly due to thyroarytenoid muscle contraction. In comparison, cooling from 37 to 7 °C decreased the basal tension and enhanced glottis ring contraction by electrical field stimulation. We concluded that warming increased the basal tension of the glottis in vitro and decreased the amplitude of electrical field stimulation-induced thyroarytenoid muscle contraction. Thus, vocal pitch and the fine tuning of vocal fold tension might be affected by temperature in vivo.

Deformation Behavior and Microstructure Evolution of As-Cast 42CrMo Alloy in Isothermal and Non-isothermal Compression

NASA Astrophysics Data System (ADS)

Qin, Fangcheng; Li, Yongtang; Qi, Huiping; Lv, Zhenhua

2016-11-01

The isothermal and non-isothermal multi-pass compression tests of centrifugal casting 42CrMo steel were conducted on a Gleeble-3500 thermal simulation machine. The effects of compression passes and finishing temperatures on deformation behavior and microstructure evolution were investigated. It is found that the microstructure is homogeneous with equiaxed grains, and the flow stress does not show significant change with the increase in passes, while the peak softening coefficient increases first and then decreases during inter-pass. Moreover, the dominant mechanisms of controlled temperature and accumulated static recrystallization for grain refinement and its homogeneous distribution are found after 5 passes deformation. As the finishing temperature increases, the flow stress decreases gradually, but the dynamic recrystallization accelerates and softening effect increases, resulting in the larger grain size and homogeneous microstructure. The microhardness decreases sharply because the sufficient softening occurs in microstructure. When the finishing temperature is 890 °C, the carbide particles are precipitated in the vicinity of the grain boundaries, thus inhibiting the dislocation motion. Thus, the higher finishing temperature (≥970 °C) for centrifugal casting 42CrMo alloy should be avoided in non-isothermal multi-pass deformation, which is beneficial to grain refinement and properties improvement.

The effect of humidified heated breathing circuit on core body temperature in perioperative hypothermia during thyroid surgery.

PubMed

Park, Hue Jung; Moon, Ho Sik; Moon, Se Ho; Do Jeong, Hyeon; Jeon, Young Jae; Do Han, Keung; Koh, Hyun Jung

2017-01-01

Purpose: During general anesthesia, human body easily reaches a hypothermic state, which is mainly caused by heat redistribution. Most studies suggested that humidified heated breathing circuits (HHBC) have little influence on maintenance of the core temperature during early phase of anesthesia. This study was aimed at examining heat preservation effect with HHBC in case of undergoing surgery with less exposure of surgical fields and short surgical duration. Methods: Patients aged 19 to 70 yr - old, ASA-PS I or II who were scheduled for elective thyroidectomy were assigned and divided to the group using HHBC (G1) and the group using conventional circuit (G2) by random allocation. During operation, core, skin, and room temperatures were measured every 5minutes by specific thermometer. Results: G1 was decreased by a lesser extent than G2 in core temperature, apparently higher at 30 and 60 minutes after induction. Skin and room temperatures showed no differences between the two groups (p>0.05). Consequently, we confirmed HHBC efficiently prevented a decrease in core temperature during early period in small operation which has difficulty in preparing warming devices or environments were not usually considered. Conclusions: This study showed that HHBC influences heat redistribution in early period of operation and can lessen the magnitude of the decrease in core body temperature. Therefore, it can be applied efficiently for other active warming devices in mild hypothermia.

Combined effects of temperature and avermectins on life history and stress response of the western flower thrips, Frankliniella occidentalis.

PubMed

Li, Hong-Bo; Zheng, Yu-Tao; Sun, Dan-Dan; Wang, Jian-Jun; Du, Yu-Zhou

2014-01-01

Temperature and pesticide are two important factors that affect survival, reproduction and other physiological processes of insects. To determine interactions of elevated temperature and avermectins treatment on the western flower thrips, Frankliniella occidentalis, newly emerged adults were exposed to combinations of three temperatures (21, 26 and 33 °C) and two avermectins concentrations (0, 45 ppm), and survival rate, reproduction, longevity, antioxidant enzymes activities and heat shock proteins (hsps) induction were analyzed. The results showed that the survival, longevity and reproduction of F. occidentalis decreased with increased temperature and avermectins treatment. While elevated temperature and avermectins treatment significantly decreased activity of SOD, activities of POD and GST significantly increased after exposure to elevated temperature, avermectins or their combination. Elevated temperature had no effect on activity of CAT, but it was obviously improved by the combination of temperature and avermectins treatment. Expression analysis of hsps showed that four heat shock proteins (hsp90, hsc702, hsp60 and hop) were up-regulated by the induction of elevated temperature with small fold changes. After treatment with avermectins, expression levels of hsp90, hsc701, hsc702 and hop were significantly up-regulated with increased temperature and higher than those of their respective control at higher temperature. Surprisingly, expression level of hps60 was down-regulated with increased temperature, but the expression level at 21 or 26 °C remained higher than that of control. Overall, our studies suggest that elevated temperature enhance toxicity of avermectins and their combination induced acute oxidative damage to F. occidentalis. Therefore, consideration of temperature in evaluating avermectins toxicity is necessary to make accurate prediction of its effect on F. occidentalis and other insects. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of Austenitising Temperature on Mechanical Properties of Nanostructured Bainitic Steel.

PubMed

Zhao, Jing; Li, Jiemin; Ji, Honghong; Wang, Tiansheng

2017-07-28

Nanostructured bainite was obtained in high-carbon Si-Al-rich steel by low-temperature (220-260 °C) isothermal transformation after austenitisation at different temperatures (900 °C, 1000 °C, and 1150 °C). Improved strength-ductility-toughness balance was achieved in the nanostructured bainitic steel austenitised at low temperatures (900 °C and 1000 °C). Increasing the austenitising temperature not only coarsened prior austenite grains and bainite packets, but also increased the size and fraction of blocky retained austenite. High austenitising temperature (1150 °C) remarkably decreased ductility and impact toughness, but had a small effect on strength and hardness.

Effect of Austenitising Temperature on Mechanical Properties of Nanostructured Bainitic Steel

PubMed Central

Zhao, Jing; Li, Jiemin; Ji, Honghong

2017-01-01

Nanostructured bainite was obtained in high-carbon Si-Al-rich steel by low-temperature (220–260 °C) isothermal transformation after austenitisation at different temperatures (900 °C, 1000 °C, and 1150 °C). Improved strength-ductility-toughness balance was achieved in the nanostructured bainitic steel austenitised at low temperatures (900 °C and 1000 °C). Increasing the austenitising temperature not only coarsened prior austenite grains and bainite packets, but also increased the size and fraction of blocky retained austenite. High austenitising temperature (1150 °C) remarkably decreased ductility and impact toughness, but had a small effect on strength and hardness. PMID:28773233

The effect of 60-h sleep deprivation on cardiovascular regulation and body temperature.

PubMed

Vaara, Jani; Kyröläinen, Heikki; Koivu, Mikko; Tulppo, Mikko; Finni, Taija

2009-02-01

This study examined cardiovascular regulation and body temperature (BT) during 60 h of sleep deprivation in 20 young healthy cadets. Heart rate variability was measured during an active orthostatic test (AOT). Measurements were performed each day in the morning and evening after 2, 14, 26, 38, 50 and 60 h of sleep deprivation. In AOT, in the sitting and standing positions, heart rate decreased (P < 0.001), while high frequency and low frequency power increased (P < 0.05-0.001) during sleep deprivation. Body temperature also decreased (P < 0.001), but no changes were detected in blood pressure. In conclusion, the accumulation of 60 h of sleep loss resulted in increased vagal outflow, as evidenced by decreased heart rate. In addition, BT decreased during sleep deprivation. Thus, sleep deprivation causes alterations in autonomic regulation of the heart, and in thermoregulation.

Rheology of water and ammonia-water ices

NASA Technical Reports Server (NTRS)

Goldsby, D. L.; Kohlstedt, D. L.; Durham, W. B.

1993-01-01

Creep experiments on fine-grained water and ammonia-water ices have been performed at one atmosphere and high confining pressure in order to develop constitutive relationships necessary to model tectonic processes and interpret surface features of icy moons of the outer solar system. The present series of experiments explores the effects of temperature, strain rate, grain size, and melt fraction on creep strength. In general, creep strength decreases with increasing temperature, decreasing strain rate, and increasing melt fraction. A transition from dislocation creep to diffusion creep occurs at finer grain sizes, higher temperatures, and lower strain rates.

Effect of artificial gravity on thermoregulation, respiratory metabolism and intermediary metabolism of animals

NASA Technical Reports Server (NTRS)

Oyama, J.

1973-01-01

Metabolic alterations in animals exposed to radial acceleration are reported. Temperatures in acutely stressed animals dropped profoundly in correlation with decreased food consumption. Repeated exposure of the acutely stressed animal caused a decrease in hypothermic response whereas deceleration or reduction of G load did not significantly change body temperatures. Adrenal corticosteroids affected significantly the animal's recovery rate. No changes occured in body temperature patterns of chronically centrifuged animals after full adaptation; their respiratory rate increased very significantly in terms of CO2 output as did their glucose uptake by muscle tissues and their insulin responsiveness or sensitivity.

Low-temperature magnetotransport of the narrow-gap semiconductor FeSb2

NASA Astrophysics Data System (ADS)

Takahashi, H.; Okazaki, R.; Yasui, Y.; Terasaki, I.

2011-11-01

We present a study of the magnetoresistance and Hall effect in the narrow-gap semiconductor FeSb2 at low temperatures. Both the electrical and Hall resistivities show unusual magnetic field dependence in the low-temperature range where a large Seebeck coefficient was observed. By applying a two-carrier model, we find that the carrier concentration decreases from 1 down to 10-4 ppm/unit cell and the mobility increases from 2000 to 28 000 cm2/Vs with decreasing temperature from 30 down to 4 K. At lower temperatures, the magnetoresistive behavior drastically changes and a negative magnetoresistance is observed at 3 K. These low-temperature behaviors are reminiscent of the low-temperature magnetotransport observed in doped semiconductors such as As-doped Ge, which is well described by a weak-localization picture. We argue a detailed electronic structure in FeSb2 inferred from our observations.

Effects of sintering temperature on electrical properties of sheep enamel hydroxyapatite

NASA Astrophysics Data System (ADS)

Dumludag, F.; Gunduz, O.; Kılıc, O.; Kılıc, B.; Ekren, N.; Kalkandelen, C.; Oktar, F. N.

2017-12-01

Bioceramics, especially calcium phosphate based bioceramics, whose examples are hydroxyapatite, and calcium phosphate powders have been widely used in the biomedical engineering applications. Hydroxyapatite (HA) is one of the most promising biomaterials, which are derived from natural sources, chemical method, animal like dental enamel and corals. The influence of sintering temperature on the electrical properties (i.e. DC conductivity, AC conductivity) of samples of sintered sheep enamel (SSSE) was studied in air and in vacuum ambient at room temperature. The sheep enamel were sintered at varying temperatures between 1000°C and 1300°C. DC conductivity results revealed that while dc conductivity of the SSSE decreases with increasing the sintering temperature in air ambient the values increased with increasing the sintering temperature in vacuum ambient. AC conductivity measurements were performed in the frequency range of 40 Hz - 105 Hz. The results showed that ac conductivity values decrease with increasing the sintering temperature.

Effect of Si-doping on InAs nanowire transport and morphology

NASA Astrophysics Data System (ADS)

Wirths, S.; Weis, K.; Winden, A.; Sladek, K.; Volk, C.; Alagha, S.; Weirich, T. E.; von der Ahe, M.; Hardtdegen, H.; Lüth, H.; Demarina, N.; Grützmacher, D.; Schäpers, Th.

2011-09-01

The effect of Si-doping on the morphology, structure, and transport properties of nanowires was investigated. The nanowires were deposited by selective-area metal organic vapor phase epitaxy in an N2 ambient. It is observed that doping systematically affects the nanowire morphology but not the structure of the nanowires. However, the transport properties of the wires are greatly affected. Room-temperature four-terminal measurements show that with an increasing dopant supply the conductivity monotonously increases. For the highest doping level the conductivity is higher by a factor of 25 compared to only intrinsically doped reference nanowires. By means of back-gate field-effect transistor measurements it was confirmed that the doping results in an increased carrier concentration. Temperature dependent resistance measurements reveal, for lower doping concentrations, a thermally activated semiconductor-type increase of the conductivity. In contrast, the nanowires with the highest doping concentration show a metal-type decrease of the resistivity with decreasing temperature.

Effect of solvent on crystallization behavior of xylitol

NASA Astrophysics Data System (ADS)

Hao, Hongxun; Hou, Baohong; Wang, Jing-Kang; Lin, Guangyu

2006-04-01

Effect of organic solvents content on crystallization behavior of xylitol was studied. Solubility and crystallization kinetics of xylitol in methanol-water system were experimentally determined. It was found that the solubility of xylitol at various methanol content all increases with increase of temperature. But it decreases when increasing methanol content at constant temperature. Based on the theory of population balance, the nucleation and growth rates of xylitol in methanol-water mixed solvents were calculated by moments method. From a series of experimental population density data of xylitol gotten from a batch-operated crystallizer, parameters of crystal nucleation and growth rate equations at different methanol content were got by the method of nonlinear least-squares. By analyzing, it was found that the content of methanol had an apparent effect on nucleation and growth rate of xylitol. At constant temperature, the nucleation and growth rate of xylitol all decrease with increase of methanol content.

Influence of salinity and temperature on acute toxicity of cadmium to Mysidopsis bahia molenock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voyer, R.A.; Modica, G.

1990-01-01

Acute toxicity tests were conducted to compare estimates of toxicity, as modified by salinity and temperature, based on response surface techniques with those derived using conventional test methods, and to compare effect of a single episodic exposure to cadmium as a function of salinity with that of continuous exposure. Regression analysis indicated that mortality following continuous 96-hr exposure is related to linear and quadratic effects of salinity and cadmium at 20 C, and to the linear and quadratic effects of cadmium only at 25C. LC50s decreased with increases in temperature and decreases in salinity. Based on the regression model developed,more » 96-hr LC50s ranged from 15.5 to 28.0 micro Cd/L at 10 and 30% salinities, respectively, at 25C; and from 47 to 85 microgram Cd/L at these salinities at 20C.« less

Utilization of solar energy in sewage sludge composting: fertilizer effect and application.

PubMed

Chen, Yiqun; Yu, Fang; Liang, Shengwen; Wang, Zongping; Liu, Zizheng; Xiong, Ya

2014-11-01

Three reactors, ordinary, greenhouse, and solar, were constructed and tested to compare their impacts on the composting of municipal sewage sludge. Greenhouse and solar reactors were designed to evaluate the use of solar energy in sludge composting, including their effects on temperature and compost quality. After 40 days of composting, it was found that the solar reactor could provide more stable heat for the composting process. The average temperature of the solar reactor was higher than that of the other two systems, and only the solar reactor could maintain the temperature above 55°C for more than 3 days. Composting with the solar reactor resulted in 31.3% decrease in the total organic carbon, increased the germination index to 91%, decreased the total nitrogen loss, and produced a good effect on pot experiments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of water temperature on perchlorate toxicity to the thyroid and reproductive system of Oryzias latipes.

PubMed

Lee, Sangwoo; Ji, Kyunghee; Choi, Kyungho

2014-10-01

Water temperature is expected to increase in many parts of the world due to global climate change. The change in water temperature may affect ecosystems through alterations of the chemical properties or by affecting the susceptibility of organisms. Perchlorate can disrupt thyroid function of an organism by inhibiting iodide uptake. In the present study, the effect of water temperature on perchlorate toxicity was evaluated using Japanese medaka (Oryzias latipes). Pairs of adult medaka fish were exposed to a sublethal concentration of sodium perchlorate (100mg/L) and a control, at a 'low' (26°C), 'medium' (29°C) or 'high' water temperature (33°C) for seven days. The effects of the water temperature on reproduction, thyroid hormones and cortisol concentrations were determined. Transcription of several genes related to thyroid function and stress were also investigated. Significant down-regulation of thyroid hormone receptor alpha (THR-α) and beta (THR-β) transcripts and up-regulation of deiodinase 2 (DIO2) transcripts were observed in the fish exposed to perchlorate. Thyroxine (T4) concentrations were decreased, while triiodothyronine (T3) levels remained constant following exposure to perchlorate, and this effect became more pronounced under the high water temperature conditions (33°C). Up-regulation of the DIO2 gene may explain these observations. The total number of spawned eggs decreased slightly as the water temperature increased, and this reduction became significant when fish were exposed to perchlorate. Our observations indicate that exposure to perchlorate could affect thyroid function and overall reproductive fitness, and these effects could be aggravated under high water temperatures. Copyright © 2014 Elsevier Inc. All rights reserved.

Biochemical and physiological responses of Carcinus maenas to temperature and the fungicide azoxystrobin.

PubMed

Rodrigues, Elsa Teresa; Moreno, António; Mendes, Tito; Palmeira, Carlos; Pardal, Miguel Ângelo

2015-08-01

Research on the effects of thermal stress is currently pertinent as climate change is expected to cause more severe climate-driven events. Carcinus maenas, a recognised estuarine model organism, was selected to test temperature-dependence of azoxystrobin toxicity, a widely applied fungicide. Crabs' responses were assessed after a 10-d acclimation at different temperatures (5°C, 22°C, and 27°C) of which the last 72h were of exposure to an environmental concentration of azoxystrobin. SOD and GST activities, mitochondrial oxygen consumption rates and protein content, as well as the Coupling Index were determined. The hypothesis proposed that extreme temperatures (5°C and 27°C) and azoxystrobin would affect crabs' responses. Results showed statistically significant different effects of SOD and all oxygen rates measured promoted by temperature, and that neither 30.3μgL(-1) of azoxystrobin nor the combined effect were crab-responsive. Protein content at 5°C was statistically higher when compared with the control temperature (22°C). The Coupling Index revealed both a slight and a drastic decrease of this index promoted by 5°C and 27°C, respectively. Regarding azoxystrobin effects, at 22°C, this index only decreased slightly. However, at extreme temperatures it fell 47% at 5°C and slightly increased at 27°C. Results provided evidence that crabs' responses to cope with low temperatures were more effective than their responses to cope with high temperatures, which are expected in future climate projections. Moreover, crabs are capable of handling environmental concentrations of azoxystrobin. However, the Coupling Index showed that combined stress factors unbalance crabs' natural capability to handle a single stressor. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Effect of Temperature on Reflectance of Materials Space Weathered by Laser Irradiation: Implications for Increased Albedo Measured by LOLA

NASA Astrophysics Data System (ADS)

Corley, L. M.; Gillis-Davis, J.; Lucey, P. G.; Trang, D.

2016-12-01

Space weathering significantly changes the optical properties of airless planetary bodies, resulting in decreased albedo, spectral reddening, and subdued absorption bands. These optical changes are caused by the presence of submicroscopic iron (SMFe) in agglutinates and patina glass, which is observed in lunar soils returned by the Apollo and Luna missions. Micrometeorite impacts and solar wind irradiation are key processes that produce SMFe. The Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter measured a trend of increased albedo at 1064 nm with decreasing temperature and a spike in 1064-nm albedo in permanently shadowed regions (PSRs). Although the LOLA albedo increase could be due to the presence of ice, increased reflectance is also consistent with reduced space weathering. It is currently unknown how temperature influences the production of SMFe and the resulting spectral effects. Low temperatures of polar regions and PSRs (as low as 50K) may affect the volume of impact melt/vaporization produced and the subsequent development of SMFe. To test this hypothesis we compare visible to near-infrared (VNIR) reflectance spectra of materials laser space weathered at low temperature and room temperature. Olivine irradiated at 88K is brighter at 1064 nm and exhibits less reddening than olivine irradiated at 295K. Radiative transfer modeling provided abundance estimates for SMFe. Based on these estimates, olivine irradiated at 88K contains 65-70% the abundance of SMFe of olivine irradiated at 295K. Laser weathering of a highlands analog at 85K results in reduced reddening but does not yield a statistically significant increased brightness at 1064 nm with lower temperature. Hence, our results show that laser weathering at low temperatures produces a measurable effect in VNIR spectra for olivine and less so for a plagioclase dominated soil. We attribute this mineral dependent observation to a decrease in the production of SMFe, and we will confirm this hypothesis with transmission electron microscopy. The 5% greater reflectance at 1064 nm for the 88K sample of olivine is consistent with the observed anticorrelation trend between temperature and LOLA albedo. Thus, reduced space weathering may contribute to the trend of increased albedo with decreasing temperature measured by LOLA.

Effect of temperature on In_{{\\varvec{x}}} Ga_{1-{{\\varvec{x}}}} As/GaAs quantum dots

NASA Astrophysics Data System (ADS)

Borji, Mahdi Ahmadi; Reyahi, Ali; Rajaei, Esfandiar; Ghahremani, Mohsen

2017-08-01

In this paper, the strain, band-edge, and energy levels of pyramidal In_x Ga_{1-x} As/GaAs quantum dots are investigated by 1-band effective mass approach. It is shown that while temperature has no remarkable effect on the strain tensor, the band gap lowers and the radiation wavelength elongates by increasing temperature. Also, band gap and energy do not linearly decrease by temperature rise. Our results appear to agree with former researches. This can be used in designing laser devices and sensors when applied in different working temperatures. Furthermore, when the device works for a long time, self-heating occurs which changes the characteristics of the output.

Effect of decreasing temperature on the strobilation of Aurelia sp.1

NASA Astrophysics Data System (ADS)

Shi, Yan; Yu, Zhigang; Zhen, Yu; Wang, Guoshan; Wang, Xungong; Mi, Tiezhu

2018-03-01

The worldwide proliferation of marine jellyfish has become a crucial ecological and social issue, and as a cosmopolitan species, Aurelia spp. have received increasing scientific attentions. In the present study, the responses of strobilation in Aurelia sp.1 to decreasing temperature were illuminated through the expression levels of the retinoid x receptor (RxR) gene and the gene encoding a secreted protein, CL390. We observed that a higher final temperature decreased the strobilation prophase and strobilation interphase periods, and the growth rate of the strobilae ratio increased with increasing CL390 gene expression. The ratio of strobilae at 12°C was highest, and the strobilae showed the higher releasing ratios at both 12°C and 16°C compared with those at 4°C and 8°C. Furthermore, more ephyrae were released at the higher final temperature. Additionally, up-regulation and down-regulation of the CL390 gene were observed in response to the four decreasing temperatures. Although the four CL390 gene transcript levels increased more significantly than the transcript levels of the RxR gene, similar trends were observed in both genes.

Effects of Temperature on Bacterial Communities and Metabolites during Fermentation of Myeolchi-Aekjeot, a Traditional Korean Fermented Anchovy Sauce.

PubMed

Jung, Ji Young; Lee, Hyo Jung; Chun, Byung Hee; Jeon, Che Ok

2016-01-01

Myeolchi-aekjeot (MA) in Korea is produced outdoors without temperature controls, which is a major obstacle to produce commercial MA products with uniform quality. To investigate the effects of temperature on MA fermentation, pH, bacterial abundance and community, and metabolites were monitored during fermentation at 15°C, 20°C, 25°C, and 30°C. Initial pH values were approximately 6.0, and pH values increased after approximately 42 days, with faster increases at higher temperatures. Bacterial abundances increased rapidly in all MA samples after quick initial decreases during early fermentation and then they again steadily decreased after reaching their maxima, which were significantly greater at higher temperatures. Bacterial community analysis revealed that Proteobacteria and Tenericutes were predominant in all initial MA samples, but they were rapidly displaced by Firmicutes as fermentation progressed. Photobacterium and Mycoplasma belonging to Proteobacteria and Tenericutes, respectively, which may include potentially pathogenic strains, were dominant in initial MA, but decreased with the growth of Chromohalobacter, which occurred faster at higher temperatures--they were dominant until 273 and 100 days at 15°C and 20°C, respectively, but not detected after 30 days at 25°C and 30°C. Chromohalobacter also decreased with the appearance of subsequent genera belonging to Firmicutes in all MA samples. Tetragenococcus, halophilic lactic acid bacteria, appeared predominantly at 20°C, 25°C, and 30°C; they were most abundant at 30°C, but not detected at 15°C. Alkalibacillus and Lentibacillus appeared as dominant genera with the decrease of Tetragenococcus at 25°C and 30°C, but only Lentibacillus was dominant at 15°C and 20°C. Metabolite analysis showed that amino acids related to tastes were major metabolites and their concentrations were relatively higher at high temperatures. This study suggests that high temperatures (approximately 30°C) may be appropriate in MA fermentation, in the light of faster disappearance of potentially pathogenic genera, higher amino acids, growth of Tetragenococcus, and faster fermentation.

Temperature and strain rate dependent behavior of polymer separator for Li-ion batteries

DOE PAGES

Kalnaus, Sergiy; Wang, Yanli; Li, Jianlin; ...

2018-03-07

Safe performance of advanced Li-ion batteries relies on integrity of the separator membrane which prevents contact between electrodes of opposite polarity. Current work provides detailed study of mechanical behavior of such membrane. Temperature and strain rate sensitivity of the triple-layer polypropylene (PP)/polyethylene (PE)/polypropylene (PP) porous separator for Li-ion batteries was studied experimentally under controlled temperatures of up to 120° (393 K), and strain rates (from 1∙10-4s-1 to 0.1s-1). Digital image correlation was used to study strain localization in separator under load. The results show significant dependence of mechanical properties on temperature, with the yield stress decreasing by 30% and elasticmore » modulus decreasing by a factor of two when the temperature is increased from 20 °C to 50 °C. The strain rate strengthening also decreased with higher temperatures while the temperature softening remained independent of the applied strain rate. Application of temperature creates long lasting changes in mechanical behavior of separator as was revealed by performing experiments after the annealing. Such delayed effect of temperature application appears to have directional dependence. The results demonstrate complex behavior of polymer separator which needs to be considered in proper safety assessments of Li-ion batteries.« less

Temperature and strain rate dependent behavior of polymer separator for Li-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalnaus, Sergiy; Wang, Yanli; Li, Jianlin

Safe performance of advanced Li-ion batteries relies on integrity of the separator membrane which prevents contact between electrodes of opposite polarity. Current work provides detailed study of mechanical behavior of such membrane. Temperature and strain rate sensitivity of the triple-layer polypropylene (PP)/polyethylene (PE)/polypropylene (PP) porous separator for Li-ion batteries was studied experimentally under controlled temperatures of up to 120° (393 K), and strain rates (from 1∙10-4s-1 to 0.1s-1). Digital image correlation was used to study strain localization in separator under load. The results show significant dependence of mechanical properties on temperature, with the yield stress decreasing by 30% and elasticmore » modulus decreasing by a factor of two when the temperature is increased from 20 °C to 50 °C. The strain rate strengthening also decreased with higher temperatures while the temperature softening remained independent of the applied strain rate. Application of temperature creates long lasting changes in mechanical behavior of separator as was revealed by performing experiments after the annealing. Such delayed effect of temperature application appears to have directional dependence. The results demonstrate complex behavior of polymer separator which needs to be considered in proper safety assessments of Li-ion batteries.« less

High-Performing, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants

NASA Technical Reports Server (NTRS)

Joshi, Prakash

2015-01-01

Long-duration space exploration will require spacecraft systems that can operate effectively over several years with minimal or no maintenance. Aerospace lubricants are key components of spacecraft systems. Physical Sciences Inc., has synthesized and characterized novel ionic liquids for use in aerospace lubricants that contribute to decreased viscosity, friction, and wear in aerospace systems. The resulting formulations offer low vapor pressure and outgassing properties and thermal stability up to 250 C. They are effective for use at temperatures as low as -70 C and provide long-term operational stability in aerospace systems. In Phase II, the company scaled several new ionic liquids and evaluated a novel formulation in a NASA testbed. The resulting lubricant compounds will offer lower volatility, decreased corrosion, and better tribological characteristics than standard liquid lubricants, particularly at lower temperatures.

Dietary tyrosine benefits cognitive and psychomotor performance during body cooling.

PubMed

O'Brien, Catherine; Mahoney, Caroline; Tharion, William J; Sils, Ingrid V; Castellani, John W

2007-02-28

Supplemental tyrosine is effective at limiting cold-induced decreases in working memory, presumably by augmenting brain catecholamine levels, since tyrosine is a precursor for catecholamine synthesis. The effectiveness of tyrosine for preventing cold-induced decreases in physical performance has not been examined. This study evaluated the effect of tyrosine supplementation on cognitive, psychomotor, and physical performance following a cold water immersion protocol that lowered body core temperature. Fifteen subjects completed a control trial (CON) in warm (35 degrees C) water and two cold water trials, each spaced a week apart. Subjects ingested an energy bar during each trial; on one cold trial (TYR) the bar contained tyrosine (300 mg/kg body weight), and on the other cold trial (PLB) and on CON the bar contained no tyrosine. Following each water immersion, subjects completed a battery of performance tasks in a cold air (10 degrees C) chamber. Core temperature was lower (p=0.0001) on PLB and TYR (both 35.5+/-0.6 degrees C) than CON (37.1+/-0.3 degrees C). On PLB, performance on a Match-to-Sample task decreased 18% (p=0.02) and marksmanship performance decreased 14% (p=0.002), compared to CON, but there was no difference between TYR and CON. Step test performance decreased by 11% (p=0.0001) on both cold trials, compared to CON. These data support previous findings that dietary tyrosine supplementation is effective for mitigating cold-induced cognitive performance such as working memory, even with reduced core temperature, and extends those findings to include the psychomotor task of marksmanship.

Synergistic effect of non-covalent interaction in colloidal nematic liquid crystal doped with magnetic functionalized single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Dalir, Nima; Javadian, Soheila

2018-03-01

Single-walled carbon nanotubes (SWCNTs), CNT@Fe3O4, and Fe3O4 nanocomposites were doped to eutectic uniaxial nematic liquid crystal (NLC's) (E5CN7) to improve physiochemical properties such as phase transition temperature, activation energy (Ea), dielectric anisotropy, and electro-optical properties. The thermal study of nematic phase shows a decrease in the nematic to isotropic phase transition temperature as CNT is doped. However, higher doping concentration of CNTs leads to the further increase in transition temperature. The anchoring effect or π-π interaction plays a key role in N-I phase transition. The functionalization of SWCNTs with Fe3O4 diminishes the CNT aggregation while the magnetic susceptibility is increased. The functionalized CNT doping to NLC's decrease significantly the phase transition temperature compared to doping of non-functionalized CNTs. Attractive interaction between guest and host molecules by magnetic and geometry effect increased the enthalpy and entropy of phase transition in the SWCNT@Fe3O4 sample compared to non-functionalized CNT doped system. Also, the Ea values are decreased as SWCNT@Fe3O4 is doped to pure E5CN7. The difference of N-I phase transition temperature was observed in Fe3O4 and CNT@Fe3O4 compared to SWCNT doped systems. Finally, dielectric anisotropy was increased in the doped system compared to pure NLC.

Effect of annealing temperature and dopant concentration on the thermoluminescence sensitivity in LiF:Mg,Cu,Ag material.

PubMed

Yahyaabadi, Akram; Torkzadeh, Falamarz; Rezaei Ochbelagh, Dariush; Hosseini Pooya, Seyed Mahdi

2018-04-24

LiF:Mg,Cu,Ag is a new dosimetry material that is similar to LiF:Mg,Cu,P in terms of dosimetric properties. The effect of the annealing temperature in the range of 200 to 350°C on the thermoluminescence (TL) sensitivity and the glow curve structure of this material at different concentrations of silver (Ag) was investigated. It has been demonstrated that the optimum values of the annealing temperature and the Ag concentration are 240°C and 0.1 mol% for better sensitivity, respectively. The TL intensity decreases at annealing temperatures lower than 240°C or higher than 240°C, reaching a minimum at 300°C and then again increases for various Ag concentrations. It was observed that the glow curve structure altered and the area under the low temperature peak as well as the area under the main dosimetric peak decreased with increasing annealing temperature. The position of the main dosimetric peak moved in the direction of higher temperatures, but at 320 and 350°C annealing temperatures, it shifted to lower temperatures. It was also observed that the TL sensitivity could partially be recovered by a combined annealing procedure. Copyright © 2018 John Wiley & Sons, Ltd.

Effects of temperature on biological activity of permafrost microorganisms.

PubMed

Kalyonova, L F; Novikova, M A; Subbotin, A M; Bazhin, A S

2015-04-01

The number and viability of microorganism specimens Bacillus spp. isolated from permafrost soil remained unchanged after incubation at temperatures of -16-37°C. Experiments on F1 CBA/Black-6 mice showed that incubation of bacteria at -5°C for 72 h promotes a decrease in their toxicity and an increase in their immunostimulating effect.

Salinity effect on the maximal growth temperature of some bacteria isolated from marine enviroments.

PubMed

Stanley, S O; Morita, R Y

1968-01-01

Salinity of the growth medium was found to have a marked effect on the maximal growth temperature of four bacteria isolated from marine sources. Vibrio marinus MP-1 had a maximal growth temperature of 21.2 C at a salinity of 35% and a maximal growth temperature of 10.5 C at a salinity of 7%, the lowest salinity at which it would grow. This effect was shown to be due to the presence of various cations in the medium. The order of effectiveness of cations in restoring the normal maximal growth temperature, when added to dilute seawater, was Na(+) > Li(+) > Mg(++) > K(+) > Rb(+) > NH(4) (+). The anions tested, with the exception of SO(4)=, had no marked effect on the maximal growth temperature response. In a completely defined medium, the highest maximal growth temperature was 20.0 C at 0.40 m NaCl. A decrease in the maximal growth temperature was observed at both low and high concentrations of NaCl.

Thermodynamics Analysis of Binary Plant Generating Power from Low-Temperature Geothermal Resource

NASA Astrophysics Data System (ADS)

Maksuwan, A.

2018-05-01

The purpose in this research was to predict tendency of increase Carnot efficiency of the binary plant generating power from low-temperature geothermal resource. Low-temperature geothermal resources or less, are usually exploited by means of binary-type energy conversion systems. The maximum efficiency is analyzed for electricity production of the binary plant generating power from low-temperature geothermal resource becomes important. By using model of the heat exchanger equivalent to a power plant together with the calculation of the combined heat and power (CHP) generation. The CHP was solved in detail with appropriate boundary originating an idea from the effect of temperature of source fluid inlet-outlet and cooling fluid supply. The Carnot efficiency from the CHP calculation was compared between condition of increase temperature of source fluid inlet-outlet and decrease temperature of cooling fluid supply. Result in this research show that the Carnot efficiency for binary plant generating power from low-temperature geothermal resource has tendency increase by decrease temperature of cooling fluid supply.

Simulated responses of terrestrial aridity to black carbon and sulfate aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, L.; Gettelman, A.; Xu, Y.

Aridity index (AI), defined as the ratio of precipitation to potential evapotranspiration (PET), is a measure of the dryness of terrestrial climate. Global climate models generally project future decreases of AI (drying) associated with global warming scenarios driven by increasing greenhouse gas and declining aerosols. Given their different effects in the climate system, scattering and absorbing aerosols may affect AI differently. In this work, we explore the terrestrial aridity responses to anthropogenic black carbon (BC) and sulfate (SO 4) aerosols with Community Earth System Model simulations. Positive BC radiative forcing decreases precipitation averaged over global land at a rate ofmore » 0.9%/°C of global mean surface temperature increase (moderate drying), while BC radiative forcing increases PET by 1.0%/°C (also drying). BC leads to a global decrease of 1.9%/°C in AI (drying). SO 4 forcing is negative and causes precipitation a decrease at a rate of 6.7%/°C cooling (strong drying). PET also decreases in response to SO 4 aerosol cooling by 6.3%/°C cooling (contributing to moistening). Thus, SO 4 cooling leads to a small decrease in AI (drying) by 0.4%/°C cooling. Despite the opposite effects on global mean temperature, BC and SO 4 both contribute to the twentieth century drying (AI decrease). Sensitivity test indicates that surface temperature and surface available energy changes dominate BC- and SO 4-induced PET changes.« less

Simulated responses of terrestrial aridity to black carbon and sulfate aerosols

DOE PAGES

Lin, L.; Gettelman, A.; Xu, Y.; ...

2016-01-27

Aridity index (AI), defined as the ratio of precipitation to potential evapotranspiration (PET), is a measure of the dryness of terrestrial climate. Global climate models generally project future decreases of AI (drying) associated with global warming scenarios driven by increasing greenhouse gas and declining aerosols. Given their different effects in the climate system, scattering and absorbing aerosols may affect AI differently. In this work, we explore the terrestrial aridity responses to anthropogenic black carbon (BC) and sulfate (SO 4) aerosols with Community Earth System Model simulations. Positive BC radiative forcing decreases precipitation averaged over global land at a rate ofmore » 0.9%/°C of global mean surface temperature increase (moderate drying), while BC radiative forcing increases PET by 1.0%/°C (also drying). BC leads to a global decrease of 1.9%/°C in AI (drying). SO 4 forcing is negative and causes precipitation a decrease at a rate of 6.7%/°C cooling (strong drying). PET also decreases in response to SO 4 aerosol cooling by 6.3%/°C cooling (contributing to moistening). Thus, SO 4 cooling leads to a small decrease in AI (drying) by 0.4%/°C cooling. Despite the opposite effects on global mean temperature, BC and SO 4 both contribute to the twentieth century drying (AI decrease). Sensitivity test indicates that surface temperature and surface available energy changes dominate BC- and SO 4-induced PET changes.« less

Simulated responses of terrestrial aridity to black carbon and sulfate aerosols: LIN: SIMULATED RESPONSES ARIDITY

DOE PAGES

Lin, L.; Gettelman, A.; Xu, Y.; ...

2016-01-27

Aridity index (AI), defined as the ratio of precipitation to potential evapotranspiration (PET), is a measure of the dryness of terrestrial climate. Global climate models generally project future decreases of AI (drying) associated with global warming scenarios driven by increasing greenhouse gas and declining aerosols. Given their different effects in the climate system, scattering and absorbing aerosols may affect AI differently. Here we explore the terrestrial aridity responses to anthropogenic black carbon (BC) and sulfate (SO4) aerosols with Community Earth System Model simulations. Positive BC radiative forcing decreases precipitation averaged over global land at a rate of 0.9%/°C of globalmore » mean surface temperature increase (moderate drying), while BC radiative forcing increases PET by 1.0%/°C (also drying). BC leads to a global decrease of 1.9%/°C in AI (drying). SO4 forcing is negative and causes precipitation a decrease at a rate of 6.7%/°C cooling (strong drying). PET also decreases in response to SO4 aerosol cooling by 6.3%/°C cooling (contributing to moistening). Thus, SO4 cooling leads to a small decrease in AI (drying) by 0.4%/°C cooling. Despite the opposite effects on global mean temperature, BC and SO4 both contribute to the twentieth century drying (AI decrease). Sensitivity test indicates that surface temperature and surface available energy changes dominate BC- and SO4-induced PET changes.« less

Periodical low eggshell temperatures during incubation and post hatch dietary arginine supplementation: Effects on performance and cold tolerance acquisition in broilers.

PubMed

Afsarian, O; Shahir, M H; Akhlaghi, A; Lotfolahian, H; Hoseini, A; Lourens, A

2016-10-01

An experiment was conducted to evaluate the effects of a periodically low eggshell temperature exposure during incubation and dietary supplementation of arginine on performance, ascites incidence, and cold tolerance acquisition in broilers. A total of 2,400 hatching eggs were randomly assigned to 2 treatment groups (16 replicates of 75 eggs per treatment). The eggs were incubated at a constant eggshell temperature (EST) of 37.8ºC throughout the incubation period (CON) or were periodically exposed to 15°C for one hour on days 11, 13, 15, and 17 of incubation and the EST was measured (periodical low EST; PLE). After hatching, 240 one-day-old male broiler chicks from both treatment groups were reared for 42 d with or without dietary arginine supplementation in a completely randomized design with a 2 × 2 factorial arrangement. In order to induce ascites, all chicks were exposed to a 15°C room temperature from 14 d onwards. Results showed that second grade chicks and yolk sac weight were decreased, and final body weight was increased in the PLE group. Ascites mortality rate was decreased only in the PLE group and dietary arginine supplementation had no apparent effect. In the PLE group, the packed cell volume (PCV) percentage and red blood cell (RBC) count were decreased. In conclusion, the results showed that the PLE treatment during incubation was associated with improved hatchability, chick quality, and productive performance of broilers and decreased ascites incidence during post hatch cold exposure. Dietary arginine supplementation had no beneficial effects in cold exposed broilers. © 2016 Poultry Science Association Inc.

Study on Collapse Mechanism of Steel Frame Structure under High Temperature and Blast Loading

NASA Astrophysics Data System (ADS)

Baoxin, Qi; Yan, Shi; Bi, Jialiang

2018-03-01

Numerical simulation analysis for collapsing process and mechanism of steel frame structures under the combined effects of fire and explosion is performed in this paper. First of all, a new steel constitutive model considering fire (high temperature softening effect) and blast (strain rate effect) is established. On the basis of the traditional Johnson-Cook model and the Perzyna model, the relationship between strain and scaled distance as well as the EOUROCODE3 standard heating curve taking into account the temperature effect parameters is introduced, and a modified Johnson-Cook constitutive model is established. Then, the influence of considering the scaled distance is introduced in order to more effectively describe the destruction and collapse phenomena of steel frame structures. Some conclusions are obtained based on the numerical analysis that the destruction will be serious and even progressively collapse with decreasing of the temperature of the steel column for the same scaled distance under the combined effects of fire and blast; the damage will be serious with decreasing of the scaled distance of the steel column under the same temperature under the combined effects of fire and blast; in the case of the combined effects of fire and blast happening in the side-spans, the partial progressive collapse occurs as the scaled distance is less than or equal to 1.28; six kinds of damages which are no damage, minor damage, moderate damage, severe damage, critical collapse, and progressive collapse.

The effects of temperature on optical properties of InGaN/GaN multiple quantum well light-emitting diodes

NASA Astrophysics Data System (ADS)

Li, Yi; Zhu, Youhua; Huang, Jing; Deng, Honghai; Wang, Meiyu; Yin, HaiHong

2017-02-01

The effects of temperature on the optical properties of InGaN/GaN quantum well (QW) light-emitting diodes have been investigated by using the six-by-six K-P method taking into account the temperature dependence of band gaps, lattice constants, and elastic constants. The numerical results indicate that the increase of temperature leads to the decrease of the spontaneous emission rate at the same injection current density due to the redistribution of carrier density and the increase of the non-radiative recombination rate. The product of Fermi-Dirac distribution functions of electron fc n and hole ( 1 - fv U m ) for the transitions between the three lowest conduction subbands (c1-c3) and the top six valence subbands (v1-v6) is larger at the lower temperature, which indicates that there are more electron-hole pairs distributed on the energy levels. It should be noted that the optical matrix elements of the inter-band transitions slightly increase at the higher temperature. In addition, the internal quantum efficiency of the InGaN/GaN QW structure is evidently decreased with increasing temperature.

Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu

NASA Astrophysics Data System (ADS)

Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin

2017-06-01

The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

Long-Term Cr Poisoning Effect on LSCF-GDC Composite Cathodes Sintered at Different Temperatures

DOE PAGES

Xiong, Chunyan; Taillon, Joshua A.; Pellegrinelli, Christopher; ...

2016-07-19

Here, the impact of sintering temperature on Cr-poisoning of solid oxide fuel cell (SOFC) cathodes was systematically studied. La 0.6Sr 0.4Fe 0.8Co 0.2O 3-δ - Ce 0.9Gd 0.1O 2-δ symmetric cells were aged at 750°C in synthetic air with the presence of Crofer 22 APU, a common high temperature interconnect, over 200 hours and electrochemical impedance spectroscopy (EIS) was used to determine the degradation process. Both the ohmic resistance (R Ω) and polarization resistance (R P) of LSCF-GDC cells, extracted from EIS spectra, for different sintering temperatures increase as a function of aging time. Furthermore, the Cr-related degradation rate increasesmore » with decreased cathode sintering temperature. The polarization resistance of cathode sintered at lower temperature (950°C) increases dramatically while aging with the presence of Cr and also significantly decreases the oxygen partial pressure dependence after aging. The degradation rate shows a positive correlation to the concentration of Cr. The results indicate that decreased sintering temperature increases the total surface area, leading to more available sites for Sr-Cr-O nucleation and thus greater Cr degradation.« less

In situ temperature relationships of biochemical and stomatal controls of photosynthesis in four lowland tropical tree species.

PubMed

Slot, Martijn; Winter, Klaus

2017-12-01

Net photosynthetic carbon uptake of Panamanian lowland tropical forest species is typically optimal at 30-32 °C. The processes responsible for the decrease in photosynthesis at higher temperatures are not fully understood for tropical trees. We determined temperature responses of maximum rates of RuBP-carboxylation (V CMax ) and RuBP-regeneration (J Max ), stomatal conductance (G s ), and respiration in the light (R Light ) in situ for 4 lowland tropical tree species in Panama. G s had the lowest temperature optimum (T Opt ), similar to that of net photosynthesis, and photosynthesis became increasingly limited by stomatal conductance as temperature increased. J Max peaked at 34-37 °C and V CMax ~2 °C above that, except in the late-successional species Calophyllum longifolium, in which both peaked at ~33 °C. R Light significantly increased with increasing temperature, but simulations with a photosynthesis model indicated that this had only a small effect on net photosynthesis. We found no evidence for Rubisco-activase limitation of photosynthesis. T Opt of V CMax and J Max fell within the observed in situ leaf temperature range, but our study nonetheless suggests that net photosynthesis of tropical trees is more strongly influenced by the indirect effects of high temperature-for example, through elevated vapour pressure deficit and resulting decreases in stomatal conductance-than by direct temperature effects on photosynthetic biochemistry and respiration. © 2017 John Wiley & Sons Ltd.

Influence of nanotube length and density on the plasmonic terahertz response of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Karlsen, P.; Shuba, M. V.; Beckerleg, C.; Yuko, D. I.; Kuzhir, P. P.; Maksimenko, S. A.; Ksenevich, V.; Viet, Ho; Nasibulin, A. G.; Tenne, R.; Hendry, E.

2018-01-01

We measure the conductivity spectra of thin films comprising bundled single-walled carbon nanotubes (CNTs) of different average lengths in the frequency range 0.3-1000 THz and temperature interval 10-530 K. The observed temperature-induced changes in the terahertz conductivity spectra are shown to depend strongly on the average CNT length, with a conductivity around 1 THz that increases/decreases as the temperature increases for short/long tubes. This behaviour originates from the temperature dependence of the electron scattering rate, which we obtain from Drude fits of the measured conductivity in the range 0.3-2 THz for 10 μm length CNTs. This increasing scattering rate with temperature results in a subsequent broadening of the observed THz conductivity peak at higher temperatures and a shift to lower frequencies for increasing CNT length. Finally, we show that the change in conductivity with temperature depends not only on tube length, but also varies with tube density. We record the effective conductivities of composite films comprising mixtures of WS2 nanotubes and CNTs versus CNT density for frequencies in the range 0.3-1 THz, finding that the conductivity increases/decreases for low/high density films as the temperature increases. This effect arises due to the density dependence of the effective length of conducting pathways in the composite films, which again leads to a shift and temperature dependent broadening of the THz conductivity peak.

A-thermal elastic behavior of silicate glasses.

PubMed

Rabia, Mohammed Kamel; Degioanni, Simon; Martinet, Christine; Le Brusq, Jacques; Champagnon, Bernard; Vouagner, Dominique

2016-02-24

Depending on the composition of silicate glasses, their elastic moduli can increase or decrease as function of the temperature. Studying the Brillouin frequency shift of these glasses versus temperature allows the a-thermal composition corresponding to an intermediate glass to be determined. In an intermediate glass, the elastic moduli are independent of the temperature over a large temperature range. For sodium alumino-silicate glasses, the a-thermal composition is close to the albite glass (NaAlSi3O8). The structural origin of this property is studied by in situ high temperature Raman scattering. The structure of the intermediate albite glass and of silica are compared at different temperatures between room temperature and 600 °C. When the temperature increases, it is shown that the high frequency shift of the main band at 440 cm(-1) in silica is a consequence of the cristobalite-like alpha-beta transformation of 6-membered rings. This effect is stronger in silica than bond elongation (anharmonic effects). As a consequence, the elastic moduli of silica increase as the temperature increases. In the albite glass, the substitution of 25% of Si(4+) ions by Al(3+) and Na(+) ions decreases the proportion of SiO2 6-membered rings responsible for the silica anomaly. The effects of the silica anomaly balance the anharmonicity in albite glass and give rise to an intermediate a-thermal glass. Different networks, formers or modifiers, can be added to produce different a-thermal glasses with useful mechanical or chemical properties.

Research on EHN additive on the diesel engine combustion characteristics in plateau environment

NASA Astrophysics Data System (ADS)

Sun, Zhixin; Li, Ruoting; Wang, Xiancheng; Hu, Chuan

2017-03-01

Aiming at the combustion deterioration problem of diesel engine in plateau environment, a bench test was carried out for the effects of EHN additive on combustion characteristics of the diesel engine with intake pressure of 0.68 kPa. Test results showed that with the full load working condition of 1 400 r/min: Cylinder pressure and pressure uprising rate decreased with EHN additive added in, mechanical load on the engine could be relieved; peak value of the heat release rate decreased and its occurrence advanced, ignition delay and combustion duration were shortened; cylinder temperature and exhaust gas temperature declined, thermal load on the engine could be relieved, output torque increased while specific oil consumption decreased, and effective thermal efficiency of diesel engine increased.

Hydraulic performance of Compacted Clay Liners (CCLs) under combined temperature and leachate exposures.

PubMed

Aldaeef, A A; Rayhani, M T

2014-12-01

Experimental investigations were carried out to investigate the effect of thermo-chemical exposures on the hydraulic performance of Compacted Clay Liners (CCLs) in landfills. Hydraulic conductivity of most CCL specimens was increased by two to three times their initial values when exposed to 55 °C for 75 days. CCL specimens also experienced increases in their hydraulic conductivities when exposed to leachate at room temperature. This behaviour could be due to the decrease in viscosity when the permeant was changed from tap water to leachate. However, as the leachate exposure time exceeded the first 15 days, hydraulic conductivity readings decreased to as much as one order of magnitude after 75 days of leachate permeation at room temperature. The gradual decrease in the CCLs hydraulic conductivities was most likely due to chemical precipitation and clogging of pore voids within the soils which seemed to reduce the effective pore volume. The rate of hydraulic conductivity reduction due to leachate permeation was slower at higher temperatures, which was attributed to the lower permeant viscosity and lower clogging occurrence. The observed hydraulic behaviours were correlated to the physical, mineral, and chemical properties of the CCLs and described below. Copyright © 2014 Elsevier Ltd. All rights reserved.

CENTRIFUGAL SEPARATORS

DOEpatents

Skarstrom, C.

1959-03-10

A centrifugal separator is described for separating gaseous mixtures where the temperature gradients both longitudinally and radially of the centrifuge may be controlled effectively to produce a maximum separation of the process gases flowing through. Tbe invention provides for the balancing of increases and decreases in temperature in various zones of the centrifuge chamber as the result of compression and expansions respectively, of process gases and may be employed effectively both to neutralize harmful temperature gradients and to utilize beneficial temperaturc gradients within the centrifuge.

Temperature measurements during high flux ion beam irradiations

DOE PAGES

Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; ...

2016-02-16

A systematic study of the ion beam heating effect was performed in a temperature range of –170 to 900 °C using a 10 MeV Au 3+ ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 × 10 12 cm –2 s –1. Different geometric configurations of beam, sample, thermocouple positioning, and sample holder were compared to understand the heat/charge transport mechanisms responsible for the observed temperature increase. The beam heating exhibited a strong dependence on the background (initial) sample temperature with the largest temperature increases occurring at cryogenic temperatures and decreasing with increasing temperature. Comparisonmore » with numerical calculations suggests that the observed heating effect is, in reality, a predominantly electronic effect and the true temperature rise is small. Furthermore, a simple model was developed to explain this electronic effect in terms of an electrostatic potential that forms during ion irradiation. Such an artificial beam heating effect is potentially problematic in thermostated ion irradiation and ion beamanalysis apparatus, as the operation of temperature feedback systems can be significantly distorted by this effect.« less

Wnt Signaling in Prostate Cancer Bone Metastases

DTIC Science & Technology

2016-11-01

of this study was to evaluate the effect of 14-day decreased food consumption on growth plate with histomorphometric analysis in rats. Experimental...directly in higher single doses. Impact statement: The effect of decreased food consumption should be taken into consideration when evaluating...similarly effective in reducing mortality in older calves (11-21days of age), with severe diarrhea (fecal score= 4), without hyperthermia ( temperature .0

The control effect of histamine on body temperature and respiratory function in IgE-dependent systemic anaphylaxis.

PubMed

Makabe-Kobayashi, Yoko; Hori, Yoshio; Adachi, Tetsuya; Ishigaki-Suzuki, Satsuki; Kikuchi, Yoshihiro; Kagaya, Yutaka; Shirato, Kunio; Nagy, András; Ujike, Azusa; Takai, Toshiyuki; Watanabe, Takehiko; Ohtsu, Hiroshi

2002-08-01

The systemic anaphylaxis reaction comprises various symptoms, including hypotension, changes in respiration pattern, and hypothermia. To elucidate the role of histamine in each of these symptoms, we induced the passive systemic anaphylaxis reaction in histidine decarboxylase gene knockout (HDC [-/-]) mice, which lack histamine. HDC(-/-) mice were generated by knocking out the HDC gene, which codes for the unique histamine-synthesizing enzyme. Twenty-four hours after the injection of IgE, HDC(+/+) and HDC(-/-) mice were injected with allergen and body temperature, blood pressure, and respiratory function were monitored in each mouse. Blood pressure dropped in both the HDC(-/-) mice and the HDC(+/+) mice. In contrast, respiratory frequency dropped and the expiratory respiration time was elongated only in the HDC(+/+) mice. Body temperature was decreased in the HDC(+/+) mice and was practically unchanged in the HDC(-/-) mice. Histamine receptor antagonists blocked the body temperature drop in the HDC(+/+) mice. Intravenous histamine induced similar patterns of body temperature decrease in the HDC(+/+) mice and the HDC(-/-) mice. Mast cell-deficient W/W (v) mice did not show the decrease in body temperature; this suggests that the histamine that contributed to the decrease in body temperature was derived from mast cells. According to the results of this investigation, in the passive systemic anaphylaxis reaction, respiratory frequency, expiratory time, and body temperature are shown to be controlled by the activity of histamine, but its contribution to blood pressure is negligible.

Increased water deficit decreases Douglas fir growth throughout western US forests.

PubMed

Restaino, Christina M; Peterson, David L; Littell, Jeremy

2016-08-23

Changes in tree growth rates can affect tree mortality and forest feedbacks to the global carbon cycle. As air temperature increases, evaporative demand also increases, increasing effective drought in forest ecosystems. Using a spatially comprehensive network of Douglas fir (Pseudotsuga menziesii) chronologies from 122 locations that represent distinct climate environments in the western United States, we show that increased temperature decreases growth via vapor pressure deficit (VPD) across all latitudes. Using an ensemble of global circulation models, we project an increase in both the mean VPD associated with the lowest growth extremes and the probability of exceeding these VPD values. As temperature continues to increase in future decades, we can expect deficit-related stress to increase and consequently Douglas fir growth to decrease throughout its US range.

Increased water deficit decreases Douglas fir growth throughout western US forests

USGS Publications Warehouse

Restaino, Christina M; Peterson, David L.; Littell, Jeremy

2016-01-01

Changes in tree growth rates can affect tree mortality and forest feedbacks to the global carbon cycle. As air temperature increases, evaporative demand also increases, increasing effective drought in forest ecosystems. Using a spatially comprehensive network of Douglas-fir (Pseudotsuga menziesii) chronologies from 122 locations that experience distinctly different climate in the western United States, we show that increased temperature decreases growth via vapor pressure deficit (VPD) across all latitudes. Under an ensemble of global circulation models, we project an increase in both the mean VPD associated with the lowest growth extremes and the probability of exceeding these VPD values. As temperature continues to increase in future decades, we can expect deficit-related stress to increase and consequently Douglas-fir growth to decrease throughout its US range.

Increased water deficit decreases Douglas fir growth throughout western US forests

PubMed Central

Restaino, Christina M.; Peterson, David L.; Littell, Jeremy

2016-01-01

Changes in tree growth rates can affect tree mortality and forest feedbacks to the global carbon cycle. As air temperature increases, evaporative demand also increases, increasing effective drought in forest ecosystems. Using a spatially comprehensive network of Douglas fir (Pseudotsuga menziesii) chronologies from 122 locations that represent distinct climate environments in the western United States, we show that increased temperature decreases growth via vapor pressure deficit (VPD) across all latitudes. Using an ensemble of global circulation models, we project an increase in both the mean VPD associated with the lowest growth extremes and the probability of exceeding these VPD values. As temperature continues to increase in future decades, we can expect deficit-related stress to increase and consequently Douglas fir growth to decrease throughout its US range. PMID:27503880

Early events in plant hypersensitive response leaves revealed by IR thermography

NASA Astrophysics Data System (ADS)

Boccara, Martine; Boue, Christine; De Paepe, Rosine; Boccara, Albert C.

2001-10-01

Infrared thermography is used to reveal the establishment of Erwinia amylovora harpin-induced hypersensitive response (HR) in Nicotiana sylvestris leaves. We observed a decrease in temperature (1-2 degree(s)C) in the harpin infiltrated zone, correlated with an increase in stomatal opening, strongly suggesting that the temperature decrease is due to higher transpiration rate. IRT experiments were conducted in a laboratory environment and could be widely applied for genotype screening and monitoring drug effects.

Effects of nisin on growth of bacteria attached to meat.

PubMed Central

Chung, K T; Dickson, J S; Crouse, J D

1989-01-01

Nisin had an inhibitory effect on gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, and Streptococcus lactis) but did not have an inhibitory effect on gram-negative bacteria (Serratia marcescens, Salmonella typhimurium, and Pseudomonas aeruginosa) attached to meat. Nisin delayed bacterial growth on meats which were artificially inoculated with L. monocytogenes or Staphylococcus aureus for at least 1 day at room temperature. If the incubation temperature was 5 degrees C, growth of L. monocytogenes was delayed for more than 2 weeks, and growth of Staphylococcus aureus did not occur. We also found that the extractable activity of nisin decreased rapidly when the meats were incubated at ambient temperatures and that this decrease was inversely related to the observed inhibitory effect. These findings disclosed that nisin delays the growth of some gram-positive bacteria attached to meat. However, nisin alone may not be sufficient to prevent meat spoilage because of the presence of gram-negative and other nisin-resistant gram-positive bacteria. PMID:2764559

MHD Flow and Heat Transfer of a Generalized Burgers’ Fluid due to a Periodic Oscillating and Periodic Heating Plate

NASA Astrophysics Data System (ADS)

Bai, Yu; Jiang, Yue-Hua; Zhang, Yan; Zhao, Hao-Jie

2017-10-01

This paper investigates the MHD flow and heat transfer of the incompressible generalized Burgers’ fluid due to a periodic oscillating plate with the effects of the second order slip and periodic heating plate. The momentum equation is formulated with multi-term fractional derivatives, and by means of viscous dissipation, the fractional derivative is considered in the energy equation. A finite difference scheme is established based on the G1-algorithm, whose convergence is confirmed by the comparison with the analytical solution in an example. Meanwhile the numerical solutions of velocity, temperature and shear stress are obtained. The effects of involved parameters on velocity and temperature fields are presented graphically and analyzed in detail. Increasing the fractional derivative parameter α, the velocity and temperature have a decreasing trend, while the influences of fractional derivative parameter β on the velocity and temperature behave conversely. Increasing the absolute value of the first order slip parameter and the second order slip parameter both cause a decrease of velocity. Furthermore, with the decreasing of the magnetic parameter, the shear stress decreases. Supported by the National Natural Science Foundations of China under Grant Nos. 21576023, 51406008, the National Key Research Program of China under Grant Nos. 2016YFC0700601, 2016YFC0700603 and the BUCEA Post Graduate Innovation Project (PG2017032)

Whole Body Vibration at Different Exposure Frequencies: Infrared Thermography and Physiological Effects

PubMed Central

Sonza, Anelise; Robinson, Caroline C.; Achaval, Matilde; Zaro, Milton A.

2015-01-01

The aim of this study was to investigate the effects of whole body vibration (WBV) on physiological parameters, cutaneous temperature, tactile sensitivity, and balance. Twenty-four healthy adults (25.3 ± 2.6 years) participated in four WBV sessions. They spent 15 minutes on a vibration platform in the vertical mode at four different frequencies (31, 35, 40, and 44 Hz) with 1 mm of amplitude. All variables were measured before and after WBV exposure. Pressure sensation in five anatomical regions and both feet was determined using Von Frey monofilaments. Postural sway was measured using a force plate. Cutaneous temperature was obtained with an infrared camera. WBV influences the discharge of the skin touch-pressure receptors, decreasing sensitivity at all measured frequencies and foot regions (P ≤ 0.05). Regarding balance, no differences were found after 20 minutes of WBV at frequencies of 31 and 35 Hz. At 40 and 44 Hz, participants showed higher anterior-posterior center of pressure (COP) velocity and length. The cutaneous temperature of the lower limbs decreased during and 10 minutes after WBV. WBV decreases touch-pressure sensitivity at all measured frequencies 10 min after exposure. This may be related to the impaired balance at higher frequencies since these variables have a role in maintaining postural stability. Vasoconstriction might explain the decreased lower limb temperature. PMID:25664338

Temperature-dependent solubility transition of Na₂SO₄ in water and the effect of NaCl therein: solution structures and salt water dynamics.

PubMed

Bharmoria, Pankaj; Gehlot, Praveen Singh; Gupta, Hariom; Kumar, Arvind

2014-11-06

Dual, aqueous solubility behavior of Na2SO4 as a function of temperatures is still a natural enigma lying unresolved in the literature. The solubility of Na2SO4 increases up to 32.38 °C and decreases slightly thereafter at higher temperatures. We have thrown light on this phenomenon by analyzing the Na2SO4-water clusters (growth and stability) detected from temperature-dependent dynamic light scattering experiments, solution compressibility changes derived from the density and speed of sound measurements, and water structural changes/Na2SO4 (ion pair)-water interactions observed from the FT-IR and 2D DOSY (1)H NMR spectroscopic investigations. It has been observed that Na2SO4-water clusters grow with an increase in Na2SO4 concentration (until the solubility transition temperature) and then start decreasing afterward. An unusual decrease in cluster size and solution compressibility has been observed with the rise in temperature for the Na2SO4 saturated solutions below the solubility transition temperature, whereas an inverse pattern is followed thereafter. DOSY experiments have indicated different types of water cluster species in saturated solutions at different temperatures with varying self-diffusion coefficients. The effect of NaCl (5-15 wt %) on the solubility behavior of Na2SO4 at different temperatures has also been examined. The studies are important from both fundamental and industrial application points of view, for example, toward the clean separation of NaCl and Na2SO4 from the effluent streams of textile and tannery industries.

Thermoregulation of dancing bees: thoracic temperature of pollen and nectar foragers in relation to profitability of foraging and colony need.

PubMed

Stabentheiner, A

2001-04-01

The thorax surface temperature of dancing honeybees (Apis mellifera carnica) recruiting nestmates to natural sources of nectar and pollen around Graz (Austria) was measured by real-time infrared thermography without touching them or disturbing social interactions. Thorax temperature during dancing was quite variable (31.4-43 degrees C). In the course of a foraging season it varied considerably and was always lower than in bees foraging from a highly profitable food source (2 molar sucrose 120 m from the hive). It averaged 38.0 degrees C (SD=2.24, n=224 dances) in the nectar foragers and 37.4 degrees C (SD=1.64, n=171) in the pollen foragers, resembling that of dancers foraging 0.5 molar sucrose from feeders with unlimited flow. Hive air temperature accounted only for about 3-8% of total variation. Foraging distance modulated dancing temperature in a way that, according to the decrease of the profitability of foraging with distance, maximum temperatures decreased and, in accordance with the increase of the dancing threshold with distance, minumum temperatures increased with distance, this way providing new support for the hypothesis that the dancing temperature is modulated by the profitability of foraging and the dancing and foraging motivation of the bees. Dancing temperature of both nectar and pollen dancers correlated with several parameters of the hive status, increasing with the amount of brood and decreasing with the amount of honey and pollen. These correlations are discussed with respect to literature reports on a colony's need for pollen and nectar, in particular the effect of brood and the amount of pollen on pollen foraging, and the effect of honey stores and demand for nectar on nectar foraging.

[Effects of temperature regime on low-light tolerance of Cucumis sativus seedling leaves in their photosynthesis].

PubMed

Li, Wei; Sui, Xiao-lei; Zhang, Zhen-xian

2008-12-01

In a phytotron, the effects of three temperature regimes (day/night 25 degrees C/18 degrees C, optimal temperature; 15 degrees C/9 degrees C, suboptimal temperature; and 9 degrees C/7 degrees C, low temperature) on the low-light (75-85 micromol x m(-2) x s(-1)) tolerance of two Cucumis sativus cultivars (shade-susceptible Jinyan 2 and shade-tolerant Deltastar) seedling leaves in their photosynthesis were studied. The results showed that under low light, the SPAD, net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), actual photochemical efficiency of PS II in the light (phi(PS II)), and photochemical quenching of chlorophyll fluorescence (q(p)) of cucumber leaves decreased, with the decrement getting more with decreasing temperature, while the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities were in adverse. During the recovery process after low-light stress relieved, the parameters of gas exchange and chlorophyll fluorescence of the leaves recovered gradually, and the recovery of some gas exchange parameters lagged to that of chlorophyll fluorescence parameters. Under low light, the lower the temperature, the more damage the photosynthesis apparatus suffered, and the lesser tolerance to low light the cucumber leaves had in their photosynthesis. During the low temperature and low light treatment period, the decrease of Pn, phi(PS II), and q(p) was more obvious for Jinyan 2 than for Deltastar; and during the relief period, the recovery of these parameters was slower for Jinyan 2 than for Deltastar. It was indicated that Jinyan 2 had weaker tolerance to low temperature and/or low light in its photosynthesis than Deltastar.

Forecasting the zeolite-containing catalyst activity in catalytic cracking technology taking into account the feedstock composition

NASA Astrophysics Data System (ADS)

Ivashkina, Elena; Nazarova, Galina; Shafran, Tatyana; Stebeneva, Valeriya

2017-08-01

The effect of the feedstock composition and the process conditions on the current catalyst activity in catalytic cracking technology using a mathematical model is performed in this research. The mathematical model takes into account the catalyst deactivation by coke for primary and secondary cracking reactions. The investigation results have shown that the feedstock has significant effect on the yield and the content of coke on the catalyst. Thus, the relative catalyst activity is significantly reduced by 7.5-10.7 %. With increasing the catalytic cracking temperature due to the catalyst flow temperature rising, the coke content and the yield per feedstock increase and the catalyst activity decreases by 5.3-7.7%. Rising the process temperature together with the catalyst circulation ratio contributes to increase of the coke yield per feedstock in the catalytic cracking and decrease of the coke content on the catalyst. It is connected with the catalyst flow rising to the riser and the contact time decreasing in the reaction zone. Also, the catalyst activity decreases in the range of 3.8-5.5% relatively to the regenerated catalyst activity (83 %).

Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter.

PubMed

Parnian, Parham; Zamir, Seyed Morteza; Shojaosadati, Seyed Abbas

2017-05-01

To study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (K L a) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. K L a values increased from 54 to 70 h -1 at 30°C and from 60 to 90 h -1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5-32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas-liquid partition coefficient and K L a increased with increasing temperature; however the effect on gas-liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs' performance.

Effect of heat shock and recovery temperature on variability of single cell lag time of Cronobacter turicensis.

PubMed

Xu, Y Zh; Métris, A; Stasinopoulos, D M; Forsythe, S J; Sutherland, J P

2015-02-01

The effect of heat stress and subsequent recovery temperature on the individual cellular lag of Cronobacter turicensis was analysed using optical density measurements. Low numbers of cells were obtained through serial dilution and the time to reach an optical density of 0.035 was determined. Assuming the lag of a single cell follows a shifted Gamma distribution with a fixed shape parameter, the effect of recovery temperature on the individual lag of untreated and sublethally heat treated cells of Cr. turicensis were modelled. It was found that the shift parameter (Tshift) increased asymptotically as the temperature decreased while the logarithm of the scale parameter (θ) decreased linearly with recovery temperature. To test the validity of the model in food, growth of low numbers of untreated and heat treated Cr. turicensis in artificially contaminated infant first milk was measured experimentally and compared with predictions obtained by Monte Carlo simulations. Although the model for untreated cells slightly underestimated the actual growth in first milk at low temperatures, the model for heat treated cells was in agreement with the data derived from the challenge tests and provides a basis for reliable quantitative microbiological risk assessments for Cronobacter spp. in infant milk. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of increasing temperature and, CO2 on quality of litter, shredders, and microorganisms in Amazonian aquatic systems

PubMed Central

Rezende, Renan de Souza; Gonçalves Júnior, José Francisco; Lopes, Aline; Piedade, Maria Teresa Fernandez; Cavalcante, Heloide de Lima; Hamada, Neusa

2017-01-01

Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams. PMID:29190723

Characteristics of 0.8- and 0.2-microns gate length In(x)Ga(1-x) As/In(0.52)Al(0.48)As/InP (0.53 less than or equal to x less than or equal to 0.70) modulation-doped field-effect transistors at cryogenic temperatures

NASA Technical Reports Server (NTRS)

Lai, Richard; Bhattacharya, Pallab K.; Yang, David; Brock, Timothy L.; Alterovitz, Samuel A.; Downey, Alan N.

1993-01-01

The performance characteristics of InP-based In(x)Ga(1-x)As/In(0.52)Al(0.48)As (0.53 is less than or equal to x is less than or equal to 0.70) pseudomorphic modulation-doped field-effect transistors (MODFET's) as a function of strain in the channel, gate, length, and temperature were investigated analytically and experimentally. The strain in the channel was varied by varying the In composition x. The temperature was varied in the range of 40-300 K and the devices have gate lengths L(sub g) of 0.8 and 0.2 microns. Analysis of the device was done using a one-dimensional self consistent solution of the Poisson and Schroedinger equations in the channel, a two-dimensional Poisson solver to obtain the channel electric field, and a Monte Carlo simulation to estimate the carrier transit times in the channel. An increase in the value of the cutoff frequency is predicted for an increase in In composition, a decrease in temperature, and a decrease in gate length. The improvements seen with decreasing temperature, decreasing gate length, and increased In composition were smaller than those predicted by analysis. The experimental results on pseudomorphic InGaAs/InAlAs MODFET's showed that there is a 15-30 percent improvement in cutoff frequency in both the 0.8- and 0.2-micron gate length devices when the temperature is lowered from 300 to 40 K.

Effects of temperature, strain rate, and vacancies on tensile and fatigue behaviors of silicon-based nanotubes

NASA Astrophysics Data System (ADS)

Jeng, Yeau-Ren; Tsai, Ping-Chi; Fang, Te-Hua

2005-02-01

This paper adopts the Tersoff-Brenner many-body potential function to perform molecular dynamics simulations of the tensile and fatigue behaviors of hypothetical silicon-based tubular nanostructures at various temperatures, strain rates, and vacancy percentages. The tensile test results indicate that with a predicted Young’s modulus of approximately 60GPa , silicon nanotubes (SiNTs) are significantly less stiff than conventional carbon nanotubes. It is observed that the presence of hydrogen has a significant influence on the tensile strength of SiNTs . Additionally, the present results indicate that the tensile strength clearly decreases with increasing temperature and with decreasing strain rate. Moreover, it is shown that the majority of the mechanical properties considered in the present study decrease with an increasing vacancy percentage. Regarding the fatigue tests, this study uses a standard theoretical model to derive curves of amplitude stress versus number of cycles for the current nanotubes. The results demonstrate that the fatigue limit of SiNTs increases with a decreasing vacancy percentage and with increasing temperature.

Adaptive latitudinal variation in Common Blackbird Turdus merula nest characteristics

PubMed Central

Mainwaring, Mark C; Deeming, D Charles; Jones, Chris I; Hartley, Ian R

2014-01-01

Nest construction is taxonomically widespread, yet our understanding of adaptive intraspecific variation in nest design remains poor. Nest characteristics are expected to vary adaptively in response to predictable variation in spring temperatures over large spatial scales, yet such variation in nest design remains largely overlooked, particularly amongst open-cup-nesting birds. Here, we systematically examined the effects of latitudinal variation in spring temperatures and precipitation on the morphology, volume, composition, and insulatory properties of open-cup-nesting Common Blackbirds’ Turdus merula nests to test the hypothesis that birds living in cooler environments at more northerly latitudes would build better insulated nests than conspecifics living in warmer environments at more southerly latitudes. As spring temperatures increased with decreasing latitude, the external diameter of nests decreased. However, as nest wall thickness also decreased, there was no variation in the diameter of the internal nest cups. Only the mass of dry grasses within nests decreased with warmer temperatures at lower latitudes. The insulatory properties of nests declined with warmer temperatures at lower latitudes and nests containing greater amounts of dry grasses had higher insulatory properties. The insulatory properties of nests decreased with warmer temperatures at lower latitudes, via changes in morphology (wall thickness) and composition (dry grasses). Meanwhile, spring precipitation did not vary with latitude, and none of the nest characteristics varied with spring precipitation. This suggests that Common Blackbirds nesting at higher latitudes were building nests with thicker walls in order to counteract the cooler temperatures. We have provided evidence that the nest construction behavior of open-cup-nesting birds systematically varies in response to large-scale spatial variation in spring temperatures. PMID:24683466

Adaptive latitudinal variation in Common Blackbird Turdus merula nest characteristics.

PubMed

Mainwaring, Mark C; Deeming, D Charles; Jones, Chris I; Hartley, Ian R

2014-03-01

Nest construction is taxonomically widespread, yet our understanding of adaptive intraspecific variation in nest design remains poor. Nest characteristics are expected to vary adaptively in response to predictable variation in spring temperatures over large spatial scales, yet such variation in nest design remains largely overlooked, particularly amongst open-cup-nesting birds. Here, we systematically examined the effects of latitudinal variation in spring temperatures and precipitation on the morphology, volume, composition, and insulatory properties of open-cup-nesting Common Blackbirds' Turdus merula nests to test the hypothesis that birds living in cooler environments at more northerly latitudes would build better insulated nests than conspecifics living in warmer environments at more southerly latitudes. As spring temperatures increased with decreasing latitude, the external diameter of nests decreased. However, as nest wall thickness also decreased, there was no variation in the diameter of the internal nest cups. Only the mass of dry grasses within nests decreased with warmer temperatures at lower latitudes. The insulatory properties of nests declined with warmer temperatures at lower latitudes and nests containing greater amounts of dry grasses had higher insulatory properties. The insulatory properties of nests decreased with warmer temperatures at lower latitudes, via changes in morphology (wall thickness) and composition (dry grasses). Meanwhile, spring precipitation did not vary with latitude, and none of the nest characteristics varied with spring precipitation. This suggests that Common Blackbirds nesting at higher latitudes were building nests with thicker walls in order to counteract the cooler temperatures. We have provided evidence that the nest construction behavior of open-cup-nesting birds systematically varies in response to large-scale spatial variation in spring temperatures.

Synergistic effects of sour taste and low temperature in suppressing the bitterness of Aminoleban® EN.

PubMed

Haraguchi, Tamami; Yoshida, Miyako; Hazekawa, Mai; Uchida, Takahiro

2011-01-01

Aminoleban® EN, a nutritional product for patients with liver failure, contains three branched-chain amino acids (BCAAs): L-leucine, L-isoleucine, and L-valine. As BCAAs are extremely bitter, Aminoleban® EN has a low palatability, which is a major cause of patient noncompliance. Nutrients for liver failure often need to be taken for long periods, and poor medication compliance can cause serious problems, such as encephalopathy. Therefore it is important to suppress the bitter taste of Aminoleban® EN and thereby improve patient compliance. There are already six different flavoured powders (coffee, green-tea, apple, fruit, plum and pineapple) which can be added to Aminoleban® EN to reduce its unpleasant taste and smell, but it is possible that other factors, such as temperature, may also improve the palatability of Aminoleban® EN. In this study, flavours alone significantly decreased the bitterness intensity of Aminoleban® EN. It was thought that the sweetness and sourness of the flavoured powder would be the main factors involved in decreasing the bitterness. However, low temperature (0-5 °C) decreased the bitterness intensity of Aminoleban® EN, with or without the flavoured powders, compared with normal room temperature (25-30 °C). The sourness intensity of flavoured powders was not decreased at low temperatures, but the sweetness intensity of some flavoured powders did decrease. These results suggest that sourness can be tasted even at low temperatures. As not only the addition of flavoured powders but also low temperatures can reduce the bitterness of Aminioleban® EN, the combination of a sour-flavoured powder and a low temperature will improve the palatability of Aminoleban® EN the most.

Effects of ingested crude and dispersed crude oil on thermoregulation in ducks (Anas platyrhynchos)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenssen, B.M.

1989-02-01

Thermoregulatory effects of ingested doses of Statfjord A crude oil and of this oil mixed with the dispersant Finasol OSR-5 were studied in adult domestic ducks (Anas platyrhynchos) exposed to ambient temperatures of +16 degrees C and -17 degrees C. The data show that ingestion of both the crude and the oil-dispersant mixture resulted in an increased body temperature during exposure to the low ambient temperature (-17 degrees C). Neither contaminant had any effect on body temperature during exposure to +16 degrees C. Ingestion of the contaminants had no effect on metabolic heat production at either ambient temperature. The breastmore » skin temperature of the ducks in both contaminated groups was significantly decreased when the ducks were exposed to the low ambient temperature. This indicates that the increase in body temperature observed in the contaminated ducks at the low ambient temperature is due to an increase in peripheral vasoconstriction.« less

Effect of annealing temperature on the properties of copper oxide films prepared by dip coating technique

NASA Astrophysics Data System (ADS)

Raship, N. A.; Sahdan, M. Z.; Adriyanto, F.; Nurfazliana, M. F.; Bakri, A. S.

2017-01-01

Copper oxide films were grown on silicon substrates by sol-gel dip coating method. In order to study the effects of annealing temperature on the properties of copper oxide films, the temperature was varied from 200 °C to 450 °C. In the process of dip coating, the substrate is withdrawn from the precursor solution with uniform velocity to obtain a uniform coating before undergoing an annealing process to make the copper oxide film polycrystalline. The physical properties of the copper oxide films were measured by an X-ray diffraction (XRD), a field emission scanning electron microscope (FESEM), an atomic force microscopy (AFM) and a four point probe instrument. From the XRD results, we found that pure cuprite (Cu2O) phase can be obtained by annealing the films annealed at 200 °C. Films annealed at 300 °C had a combination phase which consists of tenorite (CuO) and cuprite (Cu2O) phase while pure tenorite (CuO) phase can be obtained at 450 °C annealing temperature. The surface microstructure showed that the grains size is increased whereas the surface roughness is increased and then decreases by increasing in annealing temperature. The films showed that the resistivity decreased with increasing annealing temperature. Consequently, it was observed that annealing temperature has strong effects on the structural, morphological and electrical properties of copper oxide films.

Effects of Thermal Status on Markers of Blood Coagulation During Simulated Hemorrhage

DTIC Science & Technology

2017-06-01

analogous to the effects of salt consumption on blood pressure where individuals are often defined as “salt-sensitive” or “salt-insensitive” (40). For...Ventilatory parameters ( ventilation , tidal volume and breathing rate) were measured (body temperature and pressure saturated) using an automated gas...method of cooling rapidly decreases the mean skin temperature with little initial effect on Tcore (see Results). Experimental protocol 2 This

Physiologic Responses Produced by Active and Passive Personal Cooling Vests

NASA Technical Reports Server (NTRS)

Ku, Yu-Tsuan E.; Lee, Hank C.; Montgomery, Leslie D.; Luna, Bernadette

2000-01-01

Personal thermoregulatory systems which provide chest cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objectives of this study were to document and compare the subjects' response to three cooling vests in their recommended configurations. The Life Enhancement Tech (LET) lightweight active cooling vest with cap, the MicroClimate Systems Change of Phase garment (MCS), and the Steele Vest were each used to cool the chest regions of 12 male and 8 female Healthy subjects (21 to 69 yr.) in this study. The subjects, seated in an upright position at normal room temperature (approx. 22 C), were tested for 60 min. with one of the cooling garments. The LET active garment had an initial coolant fluid inlet temperature of 60 F, and was ramped down to 50 F. Oral, right and left ear canal temperatures were logged manually every 5 min. Arm, leg, chest and rectal temperatures; heart rate; and respiration were recorded continuously on a U.F.I., Inc. Biolog ambulatory monitor. For men, all three vests had similar, significant cooling effects. Decreases in the average rectal temperature, oral temperature, and ear canal temperatures were approximately 0.2 C, 0.2 C and 0.1 C, respectively. In contrast to the men, the female subjects wearing the MCS and Steel vests had similar cooling responses in which the core temperature remained elevated and oral and ear canal temperatures did not drop. The LET active garment cooled most of the female subjects in this study; rectal, oral and ear temperature decreased about 0.2 C, 0.3 C and 0.3 C, respectively. These results show that the garment configurations tested do not elicit a similar thermal response in all subjects. A gender difference is evident. The LET active garment configuration was most effective in decreasing temperatures of the female subjects; the MCS vest was least effective. For male subjects, the three vests appear to be more nearly equivalent. The active garment system under study included a cooling cap, which may account for some of the difference in response.

Effect of long-term caloric restriction on oxygen consumption and body temperature in two different strains of mice

PubMed Central

Ferguson, Melissa; Sohal, Barbara H.; Forster, Michael J.; Sohal, Rajindar S.

2007-01-01

The hypothesis, that a decrease in metabolic rate mediates the life span prolonging effect of caloric restriction (CR), was tested using two strains of mice, one of which, C57BL/6, exhibits life span extension as a result of CR, while the other, DBA/2, shows little or no effect. Comparisons of the rate of resting oxygen consumption and body temperature were made between the strains after they were fed ad libitum (AL) or maintained under 40% CR, from 4 to 16 months of age. Ad libitum-fed mice of the two strains weighed the same when young and consumed similar amounts of food throughout the experiment; however, the C57BL/6 mice weighed 25% more than DBA/2 mice at 15 months of age. The rate of oxygen consumption was normalized as per gram body weight, lean body mass or organ weight as well as per animal. The body temperature and the rate of oxygen consumption, expressed according to all of the four criteria, were decreased in the DBA/2 mice following CR. The C57BL/6 mice also showed a CR-related decrease in body temperature and in the rate of oxygen consumption per animal and when normalized according to lean body mass or organ weight. The results of this study indicate that CR indeed lowers the rate of metabolism; however, this effect by CR does not necessarily entail the prolongation of the life span of mice. PMID:17822741

Effect of long-term caloric restriction on oxygen consumption and body temperature in two different strains of mice.

PubMed

Ferguson, Melissa; Sohal, Barbara H; Forster, Michael J; Sohal, Rajindar S

2007-10-01

The hypothesis, that a decrease in metabolic rate mediates the life span prolonging effect of caloric restriction (CR), was tested using two strains of mice, one of which, C57BL/6, exhibits life span extension as a result of CR, while the other, DBA/2, shows little or no effect. Comparisons of the rate of resting oxygen consumption and body temperature were made between the strains after they were fed ad libitum (AL) or maintained under 40% CR, from 4 to 16 months of age. Ad libitum-fed mice of the two strains weighed the same when young and consumed similar amounts of food throughout the experiment; however, the C57BL/6 mice weighed 25% more than DBA/2 mice at 15 months of age. The rate of oxygen consumption was normalized as per gram body weight, lean body mass or organ weight as well as per animal. The body temperature and the rate of oxygen consumption, expressed according to all of the four criteria, were decreased in the DBA/2 mice following CR. The C57BL/6 mice also showed a CR-related decrease in body temperature and in the rate of oxygen consumption per animal and when normalized according to lean body mass or organ weight. The results of this study indicate that CR indeed lowers the rate of metabolism; however, this effect by CR does not necessarily entail the prolongation of the life span of mice.

Effects of Cooling Conditions on Tensile and Charpy Impact Properties of API X80 Linepipe Steels

NASA Astrophysics Data System (ADS)

Han, Seung Youb; Shin, Sang Yong; Lee, Sunghak; Kim, Nack J.; Bae, Jin-Ho; Kim, Kisoo

2010-02-01

In this study, four API X80 linepipe steel specimens were fabricated by varying the cooling rate and finish cooling temperature, and their microstructures and crystallographic orientations were analyzed to investigate the effects of the cooling conditions on the tensile and Charpy impact properties. All the specimens consisted of acicular ferrite (AF), granular bainite (GB), and martensite-austenite (MA) constituents. The volume fraction of MA increased with an increasing cooling rate, and the volume fraction and size of MA tended to decrease with an increasing finish cooling temperature. According to the crystallographic orientation analysis data, the effective grain size and unit crack path decreased as fine ACs having a large amount of high-angle grain boundaries were homogeneously formed, thereby leading to the improvement in the Charpy impact properties. The specimen fabricated with the higher cooling rate and lower finish cooling temperature had the highest upper-shelf energy (USE) and the lowest energy transition temperature (ETT), because it contained a large amount of MA homogeneously distributed inside fine AFs, while its tensile properties remained excellent.

High temperature monotonic and cyclic deformation in a directionally solidified nickel-base superalloy

NASA Technical Reports Server (NTRS)

Huron, Eric S.

1986-01-01

Directionally solidified (DS) MAR-M246+Hf was tested in tension and fatigue, at temperatures from 20 C to 1093 C. Tests were performed on (001) oriented specimens at strain rates of 50 % and 0.5 % per minute. In tension, the yield strength was constant up to 704 C, above which the strength dropped off rapidly. A strong dependence of strength on strain rate was seen at the higher temperatures. The deformation mode was observed to change from heterogeneous to homogeneous with increasing temperature. Low Cycle Fatigue tests were done using a fully reversed waveform and total strain control. For a given plastic strain range, lives increased with increasing temperature. For a given temperature strain rate had a strong effect on life. At 704 C, decreasing strain rates decreased life, while at the higher temperatures, decreasing strain rates increased life, for a given plastic strain range. These results could be explained through considerations of the deformation modes and stress levels. At the higher temperatures, marked coarsening caused beneficial stress reductions, but oxidation limited the life. The longitudinal grain boundaries were found to influence slip behavior. The degree of secondary slip adjacent to the boundaries was found to be related to the degree of misorientation between the grains.

Effects of Solid Solution Strengthening Elements Mo, Re, Ru, and W on Transition Temperatures in Nickel-Based Superalloys with High γ'-Volume Fraction: Comparison of Experiment and CALPHAD Calculations

NASA Astrophysics Data System (ADS)

Ritter, Nils C.; Sowa, Roman; Schauer, Jan C.; Gruber, Daniel; Goehler, Thomas; Rettig, Ralf; Povoden-Karadeniz, Erwin; Koerner, Carolin; Singer, Robert F.

2018-06-01

We prepared 41 different superalloy compositions by an arc melting, casting, and heat treatment process. Alloy solid solution strengthening elements were added in graded amounts, and we measured the solidus, liquidus, and γ'-solvus temperatures of the samples by DSC. The γ'-phase fraction increased as the W, Mo, and Re contents were increased, and W showed the most pronounced effect. Ru decreased the γ'-phase fraction. Melting temperatures (i.e., solidus and liquidus) were increased by addition of Re, W, and Ru (the effect increased in that order). Addition of Mo decreased the melting temperature. W was effective as a strengthening element because it acted as a solid solution strengthener and increased the fraction of fine γ'-precipitates, thus improving precipitation strengthening. Experimentally determined values were compared with calculated values based on the CALPHAD software tools Thermo-Calc (databases: TTNI8 and TCNI6) and MatCalc (database ME-NI). The ME-NI database, which was specially adapted to the present investigation, showed good agreement. TTNI8 also showed good results. The TCNI6 database is suitable for computational design of complex nickel-based superalloys. However, a large deviation remained between the experiment results and calculations based on this database. It also erroneously predicted γ'-phase separations and failed to describe the Ru-effect on transition temperatures.

Heated wire humidification circuit attenuates the decrease of core temperature during general anesthesia in patients undergoing arthroscopic hip surgery

PubMed Central

Park, Sooyong; Song, Seung Hyun; Hwang, Ja Gyung

2017-01-01

Background Intraoperative hypothermia is common in patients undergoing general anesthesia during arthroscopic hip surgery. In the present study, we assessed the effect of heating and humidifying the airway with a heated wire humidification circuit (HHC) to attenuate the decrease of core temperature and prevent hypothermia in patients undergoing arthroscopic hip surgery under general anesthesia. Methods Fifty-six patients scheduled for arthroscopic hip surgery were randomly assigned to either a control group using a breathing circuit connected with a heat and moisture exchanger (HME) (n = 28) or an HHC group using a heated wire humidification circuit (n = 28). The decrease in core temperature was measured from anesthetic induction and every 15 minutes thereafter using an esophageal stethoscope. Results Decrease in core temperature from anesthetic induction to 120 minutes after induction was lower in the HHC group (–0.60 ± 0.27℃) compared to the control group (–0.86 ± 0.29℃) (P = 0.001). However, there was no statistically significant difference in the incidence of intraoperative hypothermia or the incidence of shivering in the postanesthetic care unit. Conclusions The use of HHC may be considered as a method to attenuate intraoperative decrease in core temperature during arthroscopic hip surgery performed under general anesthesia and exceeding 2 hours in duration. PMID:29225745

Temperature dependence of single-event burnout in n-channel power MOSFET's

NASA Astrophysics Data System (ADS)

Johnson, G. H.; Schrimpf, R. D.; Galloway, K. F.; Koga, R.

1994-03-01

The temperature dependence of single-event burnout (SEB) in n-channel power metal-oxide-semiconductor field effect transistors (MOSFET's) is investigated experimentally and analytically. Experimental data are presented which indicate that the SEB susceptibility of the power MOSFET decreases with increasing temperature. A previously reported analytical model that describes the SEB mechanism is updated to include temperature variations. This model is shown to agree with the experimental trends.

Effect of resistant starch and aging conditions on the physicochemical properties of frozen soy yogurt.

PubMed

Rezaei, Rahil; Khomeiri, Morteza; Kashaninejad, Mahdi; Mazaheri-Tehrani, Mostafa; Aalami, Mehran

2015-12-01

The present study investigated the effects of resistant starch concentration (0, 1, 2 %), aging time (2, 13, 24 h) and aging temperature (2, 4, 6 °C) on the physicochemical properties of frozen soy yogurt. The results showed that resistant starch increased viscosity because of its water binding properties. Resistant starch also increased foam stability, fat destabilization, and hardness, but it decreased overrun and meltdown rate. Viscosity, hardness and fat destabilization increased as aging time increased. An increase in aging temperature decreased viscosity, overrun, hardness and fat destabilization of frozen yoghurt, but increased the meltdown rate.

Effects of the substitution of gallium with boron on the physical and mechanical properties of Ni-Mn-Ga shape memory alloys

NASA Astrophysics Data System (ADS)

Aydogdu, Yildirim; Turabi, Ali Sadi; Kok, Mediha; Aydogdu, Ayse; Tobe, Hirobumi; Karaca, Haluk Ersin

2014-12-01

The effects of the substitution of gallium with boron on the physical, mechanical and magnetic shape memory properties of Ni51Mn28.5Ga20.5- xBx (at.%) ( x = 0, 1, 2, 3) polycrystalline alloys are investigated. It has been found that transformation temperatures are decreasing while hardness is increasing with boron addition. B-doping of NiMnGa alloys results in the formation of a second phase that increases its ductility and strength in compression. Moreover, saturation magnetization of austenite is decreasing, while Curie temperature of austenite is increasing with B-doping.

The effects of feeding on the swimming performance and metabolic response of juvenile southern catfish, Silurus meridionalis, acclimated at different temperatures.

PubMed

Pang, Xu; Cao, Zhen-Dong; Peng, Jiang-Lan; Fu, Shi-Jian

2010-02-01

To test whether the effects of feeding on swimming performance vary with acclimation temperature in juvenile southern catfish (Silurus meridionalis), we investigated the specific dynamic action (SDA) and swimming performance of fasting and feeding fish at acclimation temperatures of 15, 21, 27, and 33 degrees C. Feeding had no effect on the critical swimming speeding (U(crit)) of fish acclimated at 15 degrees C (p=0.66), whereas it elicited a 12.04, 18.70, and 20.98% decrease in U(crit) for fish acclimated at 21, 27 and 33 degrees C, respectively (p<0.05). Both the maximal postprandial oxygen consumption rate (VO2peak) and the active metabolic rate (VO2active, maximal aerobic sustainable metabolic rate of fasting fish) increased significantly with temperature (p<0.05). The postprandial maximum oxygen consumption rates during swimming (VO2max) were higher than the VO2active of fasting fish at all temperature groups (p<0.05). The VO2max increased with increasing temperature, but the relative residual metabolic scope (VO2max-VO2peak) during swimming decreased with increasing in temperature. The present study showed that the impairment of postprandial swimming performance increased with increasing temperature due to the unparalleled changes in the catfish's central cardio-respiratory, peripheral digestive and locomotory capacities. The different metabolic strategies of juvenile southern catfish at different temperatures may relate to changes in oxygen demand, imbalances in ion fluxes and dissolved oxygen levels with changes in temperature. 2009 Elsevier Inc. All rights reserved.

The effect of temperature on amount and structure of motor variability during 2-minute maximum voluntary contraction.

PubMed

Brazaitis, Marius; Skurvydas, Albertas; Pukėnas, Kazimieras; Daniuseviciūtė, Laura; Mickevicienė, Dalia; Solianik, Rima

2012-11-01

In this study, we questioned whether local cooling of muscle or heating involving core and muscle temperatures are the main indicators for force variability. Ten volunteers performed a 2-min maximum voluntary contraction (MVC) of the knee extensors under control (CON) conditions after passive heating (HT) and cooling (CL) of the lower body. HT increased muscle and rectal temperatures, whereas CL lowered muscle temperature but did not affect rectal temperature. During 2-min MVC, peak force decreased to a lower level in HT compared with CON and CL experiments. Greater central fatigue was found in the HT experiment, and there was less in the CL experiment than in the CON experiment. Increased core and muscle temperature increased physiological tremor and the amount and structural complexity of force variability of the exercising muscles, whereas local muscle cooling decreased all force variability variables measured. Copyright © 2012 Wiley Periodicals, Inc.

Reentrant Resistive Behavior and Dimensional Crossover in Disordered Superconducting TiN Films.

PubMed

Postolova, Svetlana V; Mironov, Alexey Yu; Baklanov, Mikhail R; Vinokur, Valerii M; Baturina, Tatyana I

2017-05-11

A reentrant temperature dependence of the normal state resistance often referred to as the N-shaped temperature dependence, is omnipresent in disordered superconductors - ranging from high-temperature cuprates to ultrathin superconducting films - that experience superconductor-to-insulator transition. Yet, despite the ubiquity of this phenomenon its origin still remains a subject of debate. Here we investigate strongly disordered superconducting TiN films and demonstrate universality of the reentrant behavior. We offer a quantitative description of the N-shaped resistance curve. We show that upon cooling down the resistance first decreases linearly with temperature and then passes through the minimum that marks the 3D-2D crossover in the system. In the 2D temperature range the resistance first grows with decreasing temperature due to quantum contributions and eventually drops to zero as the system falls into a superconducting state. Our findings demonstrate the prime importance of disorder in dimensional crossover effects.

The effects of soak temperature on sugar maple seed germination

Treesearch

Carol A. Janerette

1978-01-01

The temperature at which sugar maple seeds were soaked before stratification significantly influenced their germination. Maximal germination was obtained when seeds were soaked at 4?C, but if seeds were soaked at 25?C, germination decreased and the stratification requirement increased.

Effects of Storage Duration and Temperature on the Chemical Composition, Microorganism Density, and In vitro Rumen Fermentation of Wet Brewers Grains

PubMed Central

Wang, B.; Luo, Y.; Myung, K. H.; Liu, J. X.

2014-01-01

This study aimed to investigate the effects of storage duration and temperature on the characteristics of wet brewers grains (WBG) as feeds for ruminant animals. Four storage temperatures (5°C, 15°C, 25°C, and 35°C) and four durations (0, 1, 2, and 3 d) were arranged in a 4×4 factorial design. Surface spoilage, chemical composition and microorganism density were analyzed. An in vitro gas test was also conducted to determine the pH, ammonia-nitrogen and volatile fatty acid (VFA) concentrations after 24 h incubation. Surface spoilage was apparent at higher temperatures such as 25°C and 35°C. Nutrients contents decreased concomitantly with prolonged storage times (p<0.01) and increasing temperatures (p<0.01). The amount of yeast and mold increased (p<0.05) with increasing storage times and temperatures. As storage temperature increased, gas production, in vitro disappearance of organic matter, pH, ammonia nitrogen and total VFA from the WBG in the rumen decreased (p<0.01). Our results indicate that lower storage temperature promotes longer beneficial use period. However, when storage temperature exceeds 35°C, WBG should be used within a day to prevent impairment of rumen fermentation in the subtropics such as Southeast China, where the temperature is typically above 35°C during summer. PMID:25050021

The Shubnikov-de Haas effect and thermoelectric properties of Tl-doped Sb{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulbachinskii, V. A., E-mail: kulb@mig.phys.msu.ru; Kudryashov, A. A.; Kytin, V. G.

2015-06-15

The influence of doping with Tl on the Shubnikov-de Haas effect at T = 4.2 K in magnetic fields up to 38 T in p-Sb{sub 2−x}Tl{sub x}Te{sub 3} (x = 0, 0.005, 0.015, and 0.05) and n-Bi{sub 2−x}Tl{sub x}Se{sub 3} (x = 0, 0.01, 0.02, 0.04, and 0.06) single crystals is investigated. Extreme cross-sections of the Fermi surface in both materials decrease upon doping with Tl: the hole concentration decreases in Sb{sub 2−x}Tl{sub x}Te{sub 3} due to the donor effect of Tl and the electron concentration in n-Bi{sub 2−x}Tl{sub x}Se{sub 3} decreases due to the acceptor effect of Tl. Themore » temperature dependences of the Seebeck coefficient, electrical conductivity, thermal conductivity, and dimensionless thermoelectric figure of merit in a temperature range of 77–300 K are measured. The thermal conductivity and electrical conductivity decrease upon doping with Tl both in p-Sb{sub 2−x}Tl{sub x}Te{sub 3} and in n-Bi{sub 2−x}Tl{sub x}Se{sub 3}. The Seebeck coefficient increases in all compositions upon an increase in doping over the entire measured temperature range. The thermoelectric figure of merit increases upon doping with Tl.« less

Acute Effects of Tai Chi Training on Cognitive and Cardiovascular Responses in Late Middle-Aged Adults: A Pilot Study.

PubMed

Cheung, Tiffany C Y; Liu, Karen P Y; Wong, Janet Y H; Bae, Young-Hyeon; Hui, Stanley Sai-Chuen; Tsang, William W N; Cheng, Yoyo T Y; Fong, Shirley S M

2018-01-01

This study explored the immediate effects of Tai Chi (TC) training on attention and meditation, perceived stress level, heart rate, oxygen saturation level in blood, and palmar skin temperature in late middle-aged adults. Twenty TC practitioners and 20 nonpractitioners volunteered to join the study. After baseline measurements were taken, the TC group performed TC for 10 minutes while their cognitive states and cardiovascular responses were concurrently monitored. The control group rested for the same duration in a standing position. Both groups were then reassessed. The participants' attention and meditation levels were measured using electroencephalography; stress levels were measured using Perceived Stress Scale; heart rate and blood oxygenation were measured using an oximeter; and palmar skin temperature was measured using an infrared thermometer. Attention level tended to increase during TC and dropped immediately thereafter ( p < 0.001). Perceived stress level decreased from baseline to posttest in exclusively the TC group ( p = 0.005). Heart rate increased during TC ( p < 0.001) and decreased thereafter ( p = 0.001). No significant group, time, or group-by-time interaction effects were found in the meditation level, palmar skin temperature, and blood oxygenation outcomes. While a 10-minute TC training could temporarily improve attention and decrease perceived stress levels, it could not improve meditation, palmar skin temperature, or blood oxygenation among late middle-aged adults.

Acute Effects of Tai Chi Training on Cognitive and Cardiovascular Responses in Late Middle-Aged Adults: A Pilot Study

PubMed Central

Cheung, Tiffany C. Y.; Bae, Young-Hyeon; Hui, Stanley Sai-Chuen; Cheng, Yoyo T. Y.

2018-01-01

This study explored the immediate effects of Tai Chi (TC) training on attention and meditation, perceived stress level, heart rate, oxygen saturation level in blood, and palmar skin temperature in late middle-aged adults. Twenty TC practitioners and 20 nonpractitioners volunteered to join the study. After baseline measurements were taken, the TC group performed TC for 10 minutes while their cognitive states and cardiovascular responses were concurrently monitored. The control group rested for the same duration in a standing position. Both groups were then reassessed. The participants' attention and meditation levels were measured using electroencephalography; stress levels were measured using Perceived Stress Scale; heart rate and blood oxygenation were measured using an oximeter; and palmar skin temperature was measured using an infrared thermometer. Attention level tended to increase during TC and dropped immediately thereafter (p < 0.001). Perceived stress level decreased from baseline to posttest in exclusively the TC group (p = 0.005). Heart rate increased during TC (p < 0.001) and decreased thereafter (p = 0.001). No significant group, time, or group-by-time interaction effects were found in the meditation level, palmar skin temperature, and blood oxygenation outcomes. While a 10-minute TC training could temporarily improve attention and decrease perceived stress levels, it could not improve meditation, palmar skin temperature, or blood oxygenation among late middle-aged adults. PMID:29636784

Effects of peripheral cold application on core body temperature and haemodynamic parameters in febrile patients.

PubMed

Asgar Pour, Hossein; Yavuz, Meryem

2014-04-01

This study designed to assess the effects of peripheral cold application (PCA) on core body temperature and haemodynamic parameters in febrile patients. This study was an experimental, repeated-measures performed in the neurosurgical intensive-care unit. The research sample included all patients with fever in postoperative period. PCA was performed for 20 min. During fever, systolic blood pressure, mean arterial blood pressure and arterial oxygen saturation (O2 Sat) decreased by 5.07 ± 7.89 mm Hg, 0.191 ± 6.00 mm Hg and 0.742% ± 0.97%, respectively, whereas the pulse rate and diastolic blood pressure increased by 8.528 ± 4.42 beats/ min and 1.842 ± 6.9 mmHg, respectively. Immediately after PCA, core body temperature and pulse rate decreased by 0.3°C, 3.3 beats/min, respectively, whereas systolic, diastolic, mean arterial blood pressure and O2 Sat increased by, 1.40 mm Hg, 1.87 mm Hg, 0.98 mmHg and 0.27%, respectively. Thirty minutes after the end of PCA, core body temperature, diastolic, mean arterial blood pressure and pulse rate decreased by 0.57°C, 0.34 mm Hg, 0.60 mm Hg and 4.5 beats/min, respectively, whereas systolic blood pressure and O2 Sat increased by 0.98 mm Hg and 0.04%, respectively. The present results showed that PCA increases systolic, diastolic, mean arterial blood pressure and O2 Sat, and decreases core body temperature and pulse rate. © 2013 Wiley Publishing Asia Pty Ltd.

Truncated disks - advective tori solutions around BHs. I. The effects of conduction and enhanced Coulomb coupling

NASA Astrophysics Data System (ADS)

Hujeirat, A.; Camenzind, M.

2000-10-01

We present the first 2D quasi-stationary radiative hydrodynamical calculations of accretion flows onto BHs taking into account cooling via Bremsstrahlung, Compton, Synchrotron and conduction. The effect of enhanced Coulomb coupling is investigated also. Based on the numerical results obtained, we find that two-temperature (2T) accretion flows are best suited to describe hard states, and one-temperature (1T) in the soft states, with transition possibly depending on the accretion rate. In the 2T case, the ion-conduction enlarges the disk-truncation-radius from 5 to 9 Schwarzschild radii (RS). The ion-pressure powers outflows, hence substantially decreasing the accretion rate with decreasing radius. The spectrum is partially modified BB with hard photons emitted from the inner region and showing a cutoff at 100 keV. In the 1T case, conduction decreases the truncation radius from 7 to 5 RS and lowers the maximum gas temperature. The outflows are weaker, the spectrum is pre-dominantly modified BB and the emitted photons from the inner region are much harder (up to 175 keV). In both cases, the unsaturated Comptonization region coincides with the transition region between the disk and the advective torus. When gradually enhancing the Coulomb coupling, we find that the ion-temperature Ti decreases and the electron temperature Te increases, asymptotically converging to 1T flows. However, once the dissipated energy goes into heating the ions, ion-electron thermal decoupling is inevitable within the last stable orbit (RMS) even when the Coulomb interaction is enhanced by an additional two orders of magnitude.

Annealing temperature dependence of magnetoimpedance effect in electrodeposited [Ni80fe20/Cu]3 multilayers

NASA Astrophysics Data System (ADS)

Maulana, Frendi; Eko Prastyo, W.; Nuryani; Purnama, B.

2017-11-01

We have conducted an experiment of magnetoimpedance with a variation of annealing temperature of [Ni80Fe20/Cu)]3 multilayers. The multilayer is electrodeposited on Cu-PCB substrate. Magnetoimpedance effect is impedance measure on account of external magnetic field. The found MI (magnetoimpedance) ratio is 7,63 % (without annealing) and 4,75 % (using annealing) of 100 ºC. We find that MI ratio depends on to annealing temperature and current frequence. MI ratio decreases due to rising temperature and identified increase due to the frequency. The highest MI ratio is on a sample without annealing temperature and measurement at 100 kHz frequence.

Effect of production microclimate on female thermal state with increased temperature and air humidity

NASA Technical Reports Server (NTRS)

Machablishvili, O. G.

1980-01-01

The thermal state of women during the effect of high air temperature and relative humidity with a varying degree of physical loads was studied. Parameters for air temperature, relative humidity, and air movement were established. It was established that in women the thermo-regulatory stress occurs at lower air temperatures and with lower physical loads than in men. The accumulation of heat in women was revealed with lower air temperature than in men. It is concluded that to preserve the normal physiological state of the female organism it is necessary to create more favorable microclimate conditions and decrease the physical loads.

Cannabidiol prevents infarction via the non-CB1 cannabinoid receptor mechanism.

PubMed

Hayakawa, Kazuhide; Mishima, Kenichi; Abe, Kohji; Hasebe, Nobuyoshi; Takamatsu, Fumie; Yasuda, Hiromi; Ikeda, Tomoaki; Inui, Keiichiro; Egashira, Nobuaki; Iwasaki, Katsunori; Fujiwara, Michihiro

2004-10-25

Cannabidiol, a non-psychoactive constituent of cannabis, has been reported as a neuroprotectant. Cannabidiol and Delta(9)-tetrahydrocannabinol, the primary psychoactive constituent of cannabis, significantly decreased the infarct volume at 4 h in the mouse middle cerebral artery occlusion model. The neuroprotective effects of Delta(9)-tetrahydrocannabinol but not cannabidiol were inhibited by SR141716, a cannabinoid CB1 receptor antagonist, and were abolished by warming of the animals to the levels observed in the controls. Delta(9)-Tetrahydrocannabinol significantly decreased the rectal temperature, and the hypothermic effect was inhibited by SR141716. These results surely show that the neuroprotective effect of Delta(9)-tetrahydrocannabinol are via a CB1 receptor and temperature-dependent mechanisms whereas the neuroprotective effects of cannabidiol are independent of CB1 blockade and of hypothermia.

The salinity effect in a mixed layer ocean model

NASA Technical Reports Server (NTRS)

Miller, J. R.

1976-01-01

A model of the thermally mixed layer in the upper ocean as developed by Kraus and Turner and extended by Denman is further extended to investigate the effects of salinity. In the tropical and subtropical Atlantic Ocean rapid increases in salinity occur at the bottom of a uniformly mixed surface layer. The most significant effects produced by the inclusion of salinity are the reduction of the deepening rate and the corresponding change in the heating characteristics of the mixed layer. If the net surface heating is positive, but small, salinity effects must be included to determine whether the mixed layer temperature will increase or decrease. Precipitation over tropical oceans leads to the development of a shallow stable layer accompanied by a decrease in the temperature and salinity at the sea surface.

Influence of pH, Salt and Temperature on Pressure Inactivation of Hepatitis A virus

USDA-ARS?s Scientific Manuscript database

The effects of pH (3-7), NaCl (0-6%), and temperature on pressure inactivation of hepatitis A virus (HAV) were determined. The HAV samples were treated at 400 MPa for 1 min at 5, 20, and 50C. Decreasing solution pH enhanced pressure inactivation of HAV. This enhanced inactivation effect was most e...

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

NASA Astrophysics Data System (ADS)

Kim, Jayeun; Kim, Ho

2017-03-01

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.

Utilization of potatoes for life support systems. II - The effects of temperature under 24-h and 12-h photoperiods

NASA Technical Reports Server (NTRS)

Wheeler, Raymond M.; Steffen, Kenneth L.; Tibbitts, Theodore W.; Palta, Jiwan P.

1986-01-01

The effects of temperature and the photoperiod length on the growth and tuberization of Norland potatoes were investigated for two photoperiods, 12-h and 24-hr at 400 micromol/sq m per sec PPF, and at temperatures of 12, 16, 20, 24, and 28 C. It was found that stem length increased with increasing temperature under both photoperiods. The highest tuber yield was obtained at 16 C under the 24-hr photoperiod and at 20 C under the 12-hr photoperiod (i.e., increasing the photoperiod from 12 to 24 hrs effectively decreases the optimal temperature for tuber formation). Little or no tuber formation occurred at 28 C under either photoperiod.

The Path of Carbon in Photosynthesis XII. Some Temperature Effects

DOE R&D Accomplishments Database

Ouellet, C.

1951-06-25

The photosynthetic assimilation of radioactive carbon dioxide for two-minute periods by Scenedesmus has bee studied at temperatures ranging from 25? to 44? C. All labeled intermediates cease to be formed at about 45? C. With rising temperature, the radioactivity reaching the sugar phosphate reservoirs decreases regularly while there is a sharp maximum in sucrose at 37? C. and a less pronounced one in malic and aspartic acids about 40? C. A tentative interpretation of these effects is offered.

Arginine vasopressin antagonizes the effects of prostaglandin E2 on the spontaneous activity of warm-sensitive and temperature-insensitive neurons in the medial preoptic area in rats.

PubMed

Xu, Jian-Hui; Hou, Xiao-Yu; Tang, Yu; Luo, Rong; Zhang, Jie; Liu, Chang; Yang, Yong-Lu

2018-01-01

Arginine vasopressin (AVP) plays an important role in thermoregulation and antipyresis. We have demonstrated that AVP could change the spontaneous activity of thermosensitive and temperature insensitive neurons in the preoptic area. However, whether AVP influences the effects of prostaglandin E 2 (PGE 2 ) on the spontaneous activity of neurons in the medial preoptic area (MPO) remains unclear. Our experiment showed that PGE 2 decreased the spontaneous activity of warm-sensitive neurons, and increased that of low-slope temperature-insensitive neurons in the MPO. AVP attenuated the inhibitory effect of PGE 2 on warm-sensitive neurons, and reversed the excitatory effect of PGE 2 on low-slope temperature-insensitive neurons, demonstrating that AVP antagonized the effects of PGE 2 on the spontaneous activity of these neurons. The effect of AVP was suppressed by an AVP V 1a receptor antagonist, suggesting that V 1a receptor mediated the action of AVP. We also demonstrated that AVP attenuated the PGE 2 -induced decrease in the prepotential's rate of rise in warm-sensitive neurons and the PGE 2 -induced increase in that in low-slope temperature-insensitive neurons through the V 1a receptor. Together, these data indicated that AVP antagonized the PGE 2 -induced change in the spontaneous activity of warm-sensitive and low-slope temperature-insensitive neurons in the MPO partly by reducing the PGE 2 -induced change in the prepotential of these neurons in a V 1a receptor-dependent manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of packaging and storage temperature on the survival of Listeria monocytogenes inoculated postprocessing on sliced salami.

PubMed

Gounadaki, Antonia S; Skandamis, Panagiotis N; Drosinos, Eleftherios H; Nychas, George-John E

2007-10-01

The survival of postprocess Listeria monocytogenes contamination on sliced salami, stored under the temperatures associated with retail and domestic storage, was investigated. Sliced salami was inoculated with low and high concentrations of L. monocytogenes before being packaged under vacuum or air. Survival of L. monocytogenes was determined after storage of sausages for 45 or 90 days for low or high sample inocula, respectively, at 5, 15, and 25 degrees C. All survival curves of L. monocytogenes were characterized by an initial rapid inactivation within the first days of storage, followed by a second, slower inactivation phase or "tailing." Greater reduction of L. monocytogenes was observed at the high storage temperature (25 degrees C), followed by ambient (15 degrees C) and chill (5 degrees C) storage conditions. Moreover, vacuum packaging resulted in a slower destruction of L. monocytogenes than air packaging, and this effect increased as storage temperature decreased. Although L. monocytogenes numbers decreased to undetectable levels by the end of the storage period, the time (in days) needed for this reduction and for the total elimination of the pathogen decreased with high temperature, aerobic storage, and high inoculum. Results of this study clearly indicated that the kinetics of L. monocytogenes were highly dependent on the interaction of factors such as storage temperature, packaging conditions, and initial level of contamination (inoculum). These results may contribute to the exposure assessment of quantitative microbial risk assessment and to the establishment of storage-packaging recommendations of fermented sausages.

Comparative study on the sedative effects of morphine, methadone, butorphanol or tramadol, in combination with acepromazine, in dogs.

PubMed

Monteiro, Eduardo Raposo; Junior, Adolfo Rodrigues; Assis, Hemir Martins Quirilos; Campagnol, Daniela; Quitzan, Juliany Gomes

2009-01-01

To compare the effects of morphine (MOR), methadone (MET), butorphanol (BUT) and tramadol (TRA), in combination with acepromazine, on sedation, cardiorespiratory variables, body temperature and incidence of emesis in dogs. Prospective randomized, blinded, experimental trial. Six adult mixed-breed male dogs weighing 12.0 +/- 4.3 kg. Dogs received intravenous administration (IV) of acepromazine (0.05 mg kg(-1)) and 15 minutes later, one of four opioids was randomly administered IV in a cross-over design, with at least 1-week intervals. Dogs then received MOR 0.5 mg kg(-1); MET 0.5 mg kg(-1); BUT 0.15 mg kg(-1); or TRA 2.0 mg kg(-1). Indirect systolic arterial pressure (SAP), heart rate (HR), respiratory rate (f(R)), rectal temperature, pedal withdrawal reflex and sedation were evaluated at regular intervals for 90 minutes. Acepromazine administration decreased SAP, HR and temperature and produced mild sedation. All opioids further decreased temperature and MOR, BUT and TRA were associated with further decreases in HR. Tramadol decreased SAP whereas BUT decreased f(R) compared with values before opioid administration. Retching was observed in five of six dogs and vomiting occurred in one dog in MOR, but not in any dog in the remaining treatments. Sedation scores were greater in MET followed by MOR and BUT. Tramadol was associated with minor changes in sedation produced by acepromazine alone. When used with acepromazine, MET appears to provide better sedation than MOR, BUT and TRA. If vomiting is to be avoided, MET, BUT and TRA may be better options than MOR.

Possibility of Exciton Mediated Superconductivity in Nano-Sized Sn/Si Core-Shell Clusters: A Process Technology towards Heterogeneous Material in Nano-Scale

NASA Astrophysics Data System (ADS)

Kurokawa, Yuichiro; Hihara, Takehiko; Ichinose, Ikuo; Sumiyama, Kenji

2012-07-01

We have produced Sn/Si core-shell cluster assemblies by a plasma-gas-condensation cluster beam deposition apparatus. For the sample with Si content = 12 at. %, the temperature dependence of electrical resistivity exhibits a metallic behavior above 10 K and the onset of superconducting transition below 6.1 K. With decreasing temperature, the thermomagnetic curve for the sample with Si content = 8 at. % begins to decrease steadily toward negative value below 7.7 K, indicating the Meissner effect. An increase in the transition temperature, TC is attributable to exciton-type superconductivity.

Expansion of effective wet bulb globe temperature for vapor impermeable protective clothing.

PubMed

Sakoi, Tomonori; Mochida, Tohru; Kurazumi, Yoshihito; Sawada, Shin-Ichi; Horiba, Yosuke; Kuwabara, Kohei

2018-01-01

The wet bulb globe temperature (WBGT) is an effective measure for risk screening to prevent heat dISOrders. However, a heat risk evaluation by WBGT requires adjustments depending on the clothing. In this study, we proposed a new effective WBGT (WBGT eff * ) for general vapor permeable clothing ensembles and vapor impermeable protective clothing that is applicable to occupants engaged in moderate intensity work with a metabolic heat production value of around 174W/m 2 . WBGT eff * enables the conversion of heat stress into the scale experienced by the occupant dressed in the basic clothing ensemble (work clothes) based on the heat balances for a human body. We confirmed that WBGT eff * was effective for expressing the critical thermal environments for the prescriptive zones for occupants wearing vapor impermeable protective clothing. Based on WBGT eff * , we succeeded in clarifying how the weights for natural wet bulb, globe, and air temperatures and the intercept changed depending on clothing properties and the surrounding environmental factors when heat stress is expressed by the weighted sum of natural wet bulb, globe, and air temperatures and the intercept. The weight of environmental temperatures (globe and air temperatures) for WBGT eff * for vapor impermeable protective clothing increased compared with that for general vapor permeable clothing, whereas that of the natural wet bulb temperature decreased. For WBGT eff * in outdoor conditions with a solar load, the weighting ratio of globe temperature increased and that of air temperature decreased with air velocity. Approximation equations of WBGT eff * were proposed for both general vapor permeable clothing ensembles and for vapor impermeable protective clothing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Laboratory measurement of the millimeter wave properties of liquid sulfuric acid (H2SO4). [study of microwave emission from Venus

NASA Technical Reports Server (NTRS)

Fahd, Antoine K.; Steffes, Paul G.

1991-01-01

The methodology and the results of laboratory measurements of the millimeter wave properties of liquid sulfuric acid are presented. Measurements conducted at 30-40 and 90-100 GHz are reported, using different concentrations of liquid H2SO4. The measured data are used to compute the expected opacity of H2SO4 condensates and their effects on the millimeter wave emission from Venus. The cloud condensate is found to have an effect on the emission from Venus. The calculated decrease in brightness temperature is well below the observed decrease in brightness temperature found by de Pater et al. (1991). It is suggested that other constituents such as gaseous H2SO4 also affect the observed variation in the brightness temperature.

Hyperbaric gaseous cryotherapy: effects on skin temperature and systemic vasoconstriction.

PubMed

Mourot, Laurent; Cluzeau, Christian; Regnard, Jacques

2007-10-01

To compare skin-surface cooling caused by the application of an ice bag (15min) and the projection of carbon dioxide microcristals (2min) under high pressure (75 bar) and low temperature (-78 degrees C), a modality called hyperbaric gaseous cryotherapy. Randomized controlled trial with repeated measure. Laboratory experiment. Twelve healthy male subjects (mean +/- standard deviation, 22.9+/-1.8y). Ice bag and hyperbaric gaseous cryotherapy were randomly applied on the skin of the nondominant hand. Skin temperature of the cooled (dorsal and palmar sides) and contralateral (dorsal side) hands were continuously measured with thermistor surface-contact probes before, during, and after (30min) cooling. Hyperbaric gaseous cryotherapy projection induced a large decrease (P<.05) of the dorsal skin temperature of the cooled hand (from 32.5 degrees +/-0.5 degrees C to 7.3 degrees +/-0.8 degrees C) and a significant decrease of the skin temperature of the palmar side and of the contralateral hand. The skin temperature of the dorsal side of the cooled hand was decreased with an ice bag (from 32.5 degrees +/-0.6 degrees C to 13.9 degrees +/-0.7 degrees C, P<.05). However, the lowest temperature was significantly higher than during hyperbaric gaseous cryotherapy, and no significant changes in the other skin temperatures were observed. Rewarming was equal after the 2 modalities, highlighting a more rapid increase of the skin temperature after hyperbaric gaseous cryotherapy. Hyperbaric gaseous cryotherapy projection decreased the skin temperature of the cooled and contralateral hand, suggesting a systemic skin vasoconstriction response. On the other hand, the vascular responses triggered by ice pack cooling appeared limited and localized to the cooled area.

Variation of the external quantum efficiency with temperature and current density in red, blue, and deep ultraviolet light-emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Jun Hyuk; Lee, Jong Won; Kim, Dong Yeong

The temperature-dependent external quantum efficiencies (EQEs) were investigated for a 620 nm AlGaInP red light-emitting diodes (LEDs), a 450 nm GaInN blue LED, and a 285 nm AlGaN deep-ultraviolet (DUV) LED. We observed distinct differences in the variation of the EQE with temperature and current density for the three types of LEDs. Whereas the EQE of the AlGaInP red LED increases as temperature decreases below room temperature, the EQEs of GaInN blue and AlGaN DUV LEDs decrease for the same change in temperature in a low-current density regime. The free carrier concentration, as determined from the dopant ionization energy, shows a strong material-system-specificmore » dependence, leading to different degrees of asymmetry in carrier concentration for the three types of LEDs. We attribute the EQE variation of the red, blue, and DUV LEDs to the different degrees of asymmetry in carrier concentration, which can be exacerbated at cryogenic temperatures. As for the EQE variation with temperature in a high-current density regime, the efficiency droop for the AlGaInP red and GaInN blue LEDs becomes more apparent as temperature decreases, due to the deterioration of the asymmetry in carrier concentration. However, the EQE of the AlGaN DUV LED initially decreases, then reaches an EQE minimum point, and then increases again due to the field-ionization of acceptors by the Poole-Frenkel effect. The results elucidate that carrier transport phenomena allow for the understanding of the droop phenomenon across different material systems, temperatures, and current densities.« less

Crystallization Behavior of Poly(ethylene oxide) in Vertically Aligned Carbon Nanotube Array.

PubMed

Sheng, Jiadong; Zhou, Shenglin; Yang, Zhaohui; Zhang, Xiaohua

2018-03-27

We investigate the effect of the presence of vertically aligned multiwalled carbon nanotubes (CNTs) on the orientation of poly(ethylene oxide) (PEO) lamellae and PEO crystallinity. The high alignment of carbon nanotubes acting as templates probably governs the orientation of PEO lamellae. This templating effect might result in the lamella planes of PEO crystals oriented along a direction parallel to the long axis of the nanotubes. The presence of aligned carbon nanotubes also gives rise to the decreases in PEO crystallinity, crystallization temperature, and melting temperature due to the perturbation of carbon nanotubes to the crystallization of PEO. These effects have significant implications for controlling the orientation of PEO lamellae and decreasing the crystallinity of PEO and thickness of PEO lamellae, which have significant impacts on ion transport in PEO/CNT composite and the capacitive performance of PEO/CNT composite. Both the decreased PEO crystallinity and the orientation of PEO lamellae along the long axes of vertically aligned CNTs give rise to the decrease in the charge transfer resistance, which is associated with the improvements in the ion transport and capacitive performance of PEO/CNT composite.

[Effects of low temperature on dormancy breaking and growth after planting in bulbs of Tulipa edulis].

PubMed

Yang, Ying; Zhu, Zai-Biao; Guo, Qiao-Sheng; Miao, Yuan-Yuan; Ma, Hong-Liang; Yang, Xiao-Hua

2015-01-01

The effect of low temperature storage on dormancy breaking, sprouting and growth after planting of Tulipa edulis was studied. The results showed that starch content and activity of amylases significantly decreased during 10 weeks of cold storage, soluble protein content raised at first then decreased, and the peak appeared at the 6th week. However, total soluble sugar content which in- creased slowly at first than rose sharply and reducing sugar content increased during the storage duration. The bulbs with cold storage treatment rooted in the 6th week, which was about 2 weeks earlier than room temperature storage, but there were less new roots in the late period of storage. After stored at a low temperature, bud lengths were longer than that with room temperature treatment. Cold storage treatment could promote earlier emergence, shorten germination time, prolong growth period and improve the yield of bulb, but rarely affect the emergence rate. It was not beneficial to flowering and fruiting. The results indicated that 6-8 weeks of cold storage was deemed to be the key period of dormancy breaking preliminary.

Recent changes in solar irradiance and infrared irradiance related with air temperature and cloudiness at the King Sejong Station, Antarctica

NASA Astrophysics Data System (ADS)

Jung, Y.; Kim, J.; Cho, H.; Lee, B.

2006-12-01

The polar region play a critical role in the surface energy balance and the climate system of the Earth. The important question in the region is that what is the role of the Antarctic atmospheric heat sink of global climate. Thus, this study shows the trends of global solar irradiance, infrared irradiance, air temperature and cloudiness measured at the King Sejong station, Antarctica, during the period of 1996-2004 and determines their relationship and variability of the surface energy balance. Annual average of solar radiation and cloudiness is 81.8 Wm-2 and 6.8 oktas and their trends show the decrease of -0.24 Wm-2yr-1(-0.30 %yr-1) and 0.02 oktas yr-1(0.30 %yr-1). The change of solar irradiance is directly related to change of cloudiness and decrease of solar irradiance presents radiative cooling at the surface. Monthly mean infrared irradiance, air temperature and specific humidity shows the decrease of -2.11 Wm^{- 2}yr-1(-0.75 %yr-1), -0.07 'Cyr-1(-5.15 %yr-1) and -0.044 gkg-1yr-1(-1.42 %yr-1), respectively. Annual average of the infrared irradiance is 279.9 Wm-2 and correlated with the air temperature, specific humidity and cloudiness. A multiple regression model for estimation of the infrared irradiance using the components has been developed. Effects of the components on the infrared irradiance changes show 52 %, 19 % and 10 % for air temperature, specific humidity and cloudiness, respectively. Among the components, air temperature has a great influence on infrared irradiance. Despite the increase of cloudiness, the decrease in the infrared irradiance is due to the decrease of air temperature and specific humidity which have a cooling effect. Therefore, the net radiation of the surface energy balance shows radiative cooling of negative 11-24 Wm^{- 2} during winter and radiative warming of positive 32-83 Wm-2 during the summer. Thus, the amount of shortage and surplus at the surface is mostly balanced by turbulent flux of sensible and latent heat.

Effects of Temperature on Bacterial Communities and Metabolites during Fermentation of Myeolchi-Aekjeot, a Traditional Korean Fermented Anchovy Sauce

PubMed Central

Chun, Byung Hee; Jeon, Che Ok

2016-01-01

Myeolchi-aekjeot (MA) in Korea is produced outdoors without temperature controls, which is a major obstacle to produce commercial MA products with uniform quality. To investigate the effects of temperature on MA fermentation, pH, bacterial abundance and community, and metabolites were monitored during fermentation at 15°C, 20°C, 25°C, and 30°C. Initial pH values were approximately 6.0, and pH values increased after approximately 42 days, with faster increases at higher temperatures. Bacterial abundances increased rapidly in all MA samples after quick initial decreases during early fermentation and then they again steadily decreased after reaching their maxima, which were significantly greater at higher temperatures. Bacterial community analysis revealed that Proteobacteria and Tenericutes were predominant in all initial MA samples, but they were rapidly displaced by Firmicutes as fermentation progressed. Photobacterium and Mycoplasma belonging to Proteobacteria and Tenericutes, respectively, which may include potentially pathogenic strains, were dominant in initial MA, but decreased with the growth of Chromohalobacter, which occurred faster at higher temperatures––they were dominant until 273 and 100 days at 15°C and 20°C, respectively, but not detected after 30 days at 25°C and 30°C. Chromohalobacter also decreased with the appearance of subsequent genera belonging to Firmicutes in all MA samples. Tetragenococcus, halophilic lactic acid bacteria, appeared predominantly at 20°C, 25°C, and 30°C; they were most abundant at 30°C, but not detected at 15°C. Alkalibacillus and Lentibacillus appeared as dominant genera with the decrease of Tetragenococcus at 25°C and 30°C, but only Lentibacillus was dominant at 15°C and 20°C. Metabolite analysis showed that amino acids related to tastes were major metabolites and their concentrations were relatively higher at high temperatures. This study suggests that high temperatures (approximately 30°C) may be appropriate in MA fermentation, in the light of faster disappearance of potentially pathogenic genera, higher amino acids, growth of Tetragenococcus, and faster fermentation. PMID:26977596

Are global warming and ocean acidification conspiring against marine ectotherms? A meta-analysis of the respiratory effects of elevated temperature, high CO2 and their interaction.

PubMed

Lefevre, Sjannie

2016-01-01

With the occurrence of global change, research aimed at estimating the performance of marine ectotherms in a warmer and acidified future has intensified. The concept of oxygen- and capacity-limited thermal tolerance, which is inspired by the Fry paradigm of a bell-shaped increase-optimum-decrease-type response of aerobic scope to increasing temperature, but also includes proposed negative and synergistic effects of elevated CO2 levels, has been suggested as a unifying framework. The objectives of this meta-analysis were to assess the following: (i) the generality of a bell-shaped relationship between absolute aerobic scope (AAS) and temperature; (ii) to what extent elevated CO2 affects resting oxygen uptake MO2rest and AAS; and (iii) whether there is an interaction between elevated temperature and CO2. The behavioural effects of CO2 are also briefly discussed. In 31 out of 73 data sets (both acutely exposed and acclimated), AAS increased and remained above 90% of the maximum, whereas a clear thermal optimum was observed in the remaining 42 data sets. Carbon dioxide caused a significant rise in MO2rest in only 18 out of 125 data sets, and a decrease in 25, whereas it caused a decrease in AAS in four out of 18 data sets and an increase in two. The analysis did not reveal clear evidence for an overall correlation with temperature, CO2 regime or duration of CO2 treatment. When CO2 had an effect, additive rather than synergistic interactions with temperature were most common and, interestingly, they even interacted antagonistically on MO2rest and AAS. The behavioural effects of CO2 could complicate experimental determination of respiratory performance. Overall, this meta-analysis reveals heterogeneity in the responses to elevated temperature and CO2 that is not in accordance with the idea of a single unifying principle and which cannot be ignored in attempts to model and predict the impacts of global warming and ocean acidification on marine ectotherms.

Are global warming and ocean acidification conspiring against marine ectotherms? A meta-analysis of the respiratory effects of elevated temperature, high CO2 and their interaction

PubMed Central

Lefevre, Sjannie

2016-01-01

Abstract With the occurrence of global change, research aimed at estimating the performance of marine ectotherms in a warmer and acidified future has intensified. The concept of oxygen- and capacity-limited thermal tolerance, which is inspired by the Fry paradigm of a bell-shaped increase–optimum–decrease-type response of aerobic scope to increasing temperature, but also includes proposed negative and synergistic effects of elevated CO2 levels, has been suggested as a unifying framework. The objectives of this meta-analysis were to assess the following: (i) the generality of a bell-shaped relationship between absolute aerobic scope (AAS) and temperature; (ii) to what extent elevated CO2 affects resting oxygen uptake MO2rest and AAS; and (iii) whether there is an interaction between elevated temperature and CO2. The behavioural effects of CO2 are also briefly discussed. In 31 out of 73 data sets (both acutely exposed and acclimated), AAS increased and remained above 90% of the maximum, whereas a clear thermal optimum was observed in the remaining 42 data sets. Carbon dioxide caused a significant rise in MO2rest in only 18 out of 125 data sets, and a decrease in 25, whereas it caused a decrease in AAS in four out of 18 data sets and an increase in two. The analysis did not reveal clear evidence for an overall correlation with temperature, CO2 regime or duration of CO2 treatment. When CO2 had an effect, additive rather than synergistic interactions with temperature were most common and, interestingly, they even interacted antagonistically on MO2rest and AAS. The behavioural effects of CO2 could complicate experimental determination of respiratory performance. Overall, this meta-analysis reveals heterogeneity in the responses to elevated temperature and CO2 that is not in accordance with the idea of a single unifying principle and which cannot be ignored in attempts to model and predict the impacts of global warming and ocean acidification on marine ectotherms. PMID:27382472

Monoterpene and sesquiterpene emissions from Quercus coccifera exhibit interacting responses to light and temperature

NASA Astrophysics Data System (ADS)

Staudt, M.; Lhoutellier, L.

2011-09-01

Light and temperature are known to be the most important environmental factors controlling biogenic volatile organic compound (BVOC) emissions from plants, but little is known about their interdependencies especially for BVOCs other than isoprene. We studied light responses at different temperatures and temperature responses at different light levels of foliar BVOC emissions, photosynthesis and chlorophyll fluorescence on Quercus coccifera, an evergreen oak widespread in Mediterranean shrublands. More than 50 BVOCs were detected in the emissions from Q. coccifera leaves most of them being isoprenoids plus a few green leaf volatiles (GLVs). Under standard conditions non-oxygenated monoterpenes (MT-hc) accounted for about 90% of the total BVOC release (mean ± SD: 738 ± 378 ng m-2 projected leaf area s-1 or 13.1 ± 6.9 μg g-1 leaf dry weight h-1) and oxygenated monoterpenes (MT-ox) and sesquiterpenes (SQTs) accounted for the rest in about equal proportions. Except GLVs, emissions of all BVOCs responded positively to light and temperature. The light responses of MT and SQT emissions resembled that of CO2-assimilation and were little influenced by the assay temperature: at high assay temperature, MT-hc emissions saturated at lower light levels than at standard assay temperature and tended even to decrease in the highest light range. The emission responses to temperature showed mostly Arrhenius-type response curves, whose shapes in the high temperature range were clearly affected by the assay light level and were markedly different between isoprenoid classes: at non-saturating light, all isoprenoids showed a similar temperature optimum (~43 °C), but, at higher temperatures, MT-hc emissions decreased faster than MT-ox and SQT emissions. At saturating light, MT-hc emissions peaked around 37 °C and rapidly dropped at higher temperatures, whereas MT-ox and SQT emissions strongly increased between 40 and 50 °C accompanied by a burst of GLVs. In all experiments, decreases of MT-hc emissions under high temperatures were correlated with decreases in CO2-assimilation and/or photosynthetic electron transport. We conclude that light and temperature can have interactive short-term effects on the quantity and quality of BVOC emissions from Q. coccifera through substrate limitations of MT biosynthesis occurring at temperatures supraoptimal for photosynthetic processes that are exacerbated by oxidative stress and membrane damages. Such interactive effects are likely to occur frequently during hot and dry summers and simulations made in this work showed that they may have important consequences for emission predictions.

Monoterpene and sesquiterpene emissions from Quercus coccifera exhibit interacting responses to light and temperature

NASA Astrophysics Data System (ADS)

Staudt, M.; Lhoutellier, L.

2011-06-01

Light and temperature are known to be the most important environmental factors controlling biogenic volatile organic compound (BVOC) emissions from plants, but little is known about their interdependencies especially for BVOCs other than isoprene. We studied light responses at different temperatures and temperature responses at different light levels of foliar BVOC emissions, photosynthesis and chlorophyll fluorescence on Quercus coccifera, an evergreen oak widespread in Mediterranean shrublands. More than 50 BVOCs were detected in the emissions from Q. coccifera leaves most of them being isoprenoids plus a few green leaf volatiles (GLVs). Under standard conditions non-oxygenated monoterpenes (MT-hc) accounted for about 90 % of the total BVOC release (mean ± SD: 738 ± 378 ng m-2 projected leaf area s-1 or 13.1 ± 6.9 μg g-1 leaf dry weight h-1) and oxygenated monoterpenes (MT-ox) and sesquiterpenes (SQTs) accounted for the rest in about equal proportions. Except GLVs, emissions of all BVOCs responded positively to light and temperature. The light responses of MT and SQT emissions resembled that of CO2-assimilation and were little influenced by the assay temperature: at high assay temperature, MT-hc emissions saturated at lower light levels than at standard assay temperature and tended even to decrease in the highest light range. The emission responses to temperature showed mostly Arrhenius-type response curves, whose shapes in the high temperature range were clearly affected by the assay light level and were markedly different between isoprenoid classes: at non-saturating light, all isoprenoids showed a similar temperature optimum (~43 °C), but, at higher temperatures, MT-hc emissions decreased faster than MT-ox and SQT emissions. At saturating light, MT-hc emissions peaked already around 37 °C and rapidly dropped at higher temperatures, whereas MT-ox and SQT emissions strongly increased between 40 and 50 °C accompanied by a burst of GLVs. In all experiments, decreases of MT-hc emissions under high temperatures were correlated with decreases in CO2-assimilation and/or photosynthetic electron transport. We conclude that light and temperature can have interactive short-term effects on the quantity and quality of BVOC emissions from Q. coccifera through substrate limitations of MT biosynthesis occurring at temperatures supraoptimal for photosynthetic processes that are exacerbated by oxidative stress and membrane damages. Such interactive effects are likely to occur frequently during hot and dry summers and simulations made in this work showed that they may have important consequences for emission predictions.

Effect of sintering temperature on the microstructure and properties of foamed glass-ceramics prepared from high-titanium blast furnace slag and waste glass

NASA Astrophysics Data System (ADS)

Chen, Chang-hong; Feng, Ke-qin; Zhou, Yu; Zhou, Hong-ling

2017-08-01

Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature (900-1060°C) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060°C. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength (16.64 MPa) among the investigated samples and a relatively low bulk density (0.83 g/cm3), were attained in the case of the foamed glass-ceramics sintered at 1000°C.

Effect of marination in gravy on the radio frequency and microwave processing properties of beef.

PubMed

Basaran-Akgul, Nese; Rasco, Barbara A

2015-02-01

Dielectric properties (the dielectric constant (ε') and the dielectric loss factor (ε″)) and the penetration depth of raw eye of round beef Semitendinosus muscle, raw beef marinated in gravy, raw beef cooked in gravy, and gravy alone were determined as a function of the temperature (20-130 °C) and frequency (27-1,800 MHz). Both ε' and ε″ values increased as the temperature increased at low frequencies (27 and 40 MHz). At high frequencies (915 and 1,800 MHz), ε' showed a 50 % decrease while ε″ increased nearly three fold with increasing temperature in the range from 20 to 130 °C. ε' increased gradually while ε″ increased five fold when the temperature increased from 20 to 130 °C. Both ε' and ε″ of all samples decreased with increase in frequency. Marinating the beef in gravy dramatically increased the ε″ values, particularly at the lower frequencies. Power penetration depth of all samples decreased with increase temperature and frequency. These results are expected to provide useful data for modeling dielectric heating processes of marinated muscle food.

Protracted effects of chronic stress on serotonin-dependent thermoregulation.

PubMed

Natarajan, Reka; Northrop, Nicole A; Yamamoto, Bryan K

2015-01-01

Chronic stress is known to affect serotonin (5HT) neurotransmission in the brain and to alter body temperature. The body temperature is controlled in part, by the medial preoptic area (mPOA) of the hypothalamus. To investigate the effect of chronic stress on 5HT and how it affects body temperature regulation, we examined whether exposure to a chronic unpredictable stress (CUS) paradigm produces long-term alterations in thermoregulatory function of the mPOA through decreased 5HT neurotransmission. Adult male Sprague-Dawley rats underwent 21 d of CUS. Four days after the last stress exposure, basal body temperature in the home cage and body temperature in a cold room maintained at 10 °C were recorded. The CUS rats had significantly higher subcutaneous basal body temperature at 13:00 h compared to unstressed (NoStress) rats. Whereas the NoStress rats were able to significantly elevate body temperature from basal levels at 30 and 60 min of exposure to the cold room, the CUS rats showed a hypothermic response to the cold. Treatment during CUS with metyrapone, a corticosterone synthesis inhibitor, blocked stress-induced decrease in body temperature in response to the cold challenge. CUS also decreased 5HT transporter protein immunoreactivity in the mPOA and 5HT2A/C agonist injection into the mPOA after CUS exposure caused stressed rats to exhibit a sensitized hyperthermic response to cold. These results indicate that the CUS induced changes to the 5HTergic system alter mPOA function in thermoregulation. These findings help us to explain the mechanisms underlying chronic stress-induced disorders such as chronic fatigue syndrome wherein long lasting thermoregulatory deficits are observed.

Protracted effects of chronic stress on serotonin dependent thermoregulation

PubMed Central

Natarajan, Reka; Northrop, Nicole A.; Yamamoto, Bryan K.

2016-01-01

Chronic stress is known to affect serotonin (5HT) neurotransmission in the brain and to alter body temperature. Body temperature is controlled in part, by the medial preoptic area of the hypothalamus (mPOA). To investigate the effect of chronic stress on 5HT and how it affects body temperature regulation, we examined whether exposure to a chronic unpredictable stress paradigm (CUS) produces long-term alterations in thermoregulatory function of the mPOA through decreased 5HT neurotransmission. Adult male Sprague-Dawley rats underwent 21 days of CUS. Four days after last stress exposure, basal body temperature in the home cage and body temperature in a cold room maintained at 10°C were recorded. CUS rats had significantly higher subcutaneous basal body temperature at 13:00 h compared to unstressed (NoStress) rats. Whereas the NoStress rats were able to significantly elevate body temperature from basal levels at 30 and 60 min of exposure to the cold room, the CUS rats showed a hypothermic response to the cold. Treatment during CUS with metyrapone, a corticosterone synthesis inhibitor, blocked stress-induced decrease in body temperature in response to the cold challenge. CUS also decreased 5HT transporter protein immunoreactivity in the mPOA and 5HT2A/C agonist injection into the mPOA after CUS exposure caused stressed rats to exhibit a sensitized hyperthermic response to cold. These results indicate that CUS induced changes to the 5HTergic system alters mPOA function in thermoregulation. These findings help explain mechanisms underlying chronic stress induced disorders such as chronic fatigue syndrome wherein long lasting thermoregulatory deficits are observed. PMID:26414686

Effect of selected water temperatures used in Mycoplasma gallisepticum vaccine reconstitution on titer at selected time intervals.

PubMed

Branton, S L; Leigh, S A; Roush, W B; Purswell, J L; Olanrewaju, H A; Collier, S D

2008-06-01

Numerous methods are currently used throughout the poultry industry for the administration of vaccines. Each utilizes water for vaccine reconstitution and/or administration, including two of the three commercially available live Mycoplasma gallisepticum (MG) vaccines. Selected water temperatures were used to reconstitute and/or dilute the three commercially available live MG vaccines. Water temperatures included 4 C, 22 C (room temperature), and 32 C, and titer (color change units) was recorded at four time intervals, at point of reconstitution (time 0), 15, 30, and 60 min postreconstitution of the vaccines (time periods 15, 30, and 60, respectively). Results for F strain MG (FMG) vaccine showed significant decreases in titer from time 0 to time 15 for the 22 C and 32 C water temperatures but no significant decrease for any time period for FMG reconstituted with 4 C water. For 6/85 strain MG no significant difference in titer was noted for any of four time periods within any of the three water temperatures. For ts-11 strain MG a significant decrease was observed in titer at each of the four postdilution time periods when diluted with 32 C water. There was no significant decrease in titer at any time period for ts-11 MG vaccine when diluted with either 4 C or 22 C water.

Sudden collapse of vacuoles in Saintpaulia sp. palisade cells induced by a rapid temperature decrease.

PubMed

Kadohama, Noriaki; Goh, Tatsuaki; Ohnishi, Miwa; Fukaki, Hidehiro; Mimura, Tetsuro; Suzuki, Yoshihiro

2013-01-01

It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. 'Iceberg') and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury.

Sudden Collapse of Vacuoles in Saintpaulia sp. Palisade Cells Induced by a Rapid Temperature Decrease

PubMed Central

Kadohama, Noriaki; Goh, Tatsuaki; Ohnishi, Miwa; Fukaki, Hidehiro; Mimura, Tetsuro; Suzuki, Yoshihiro

2013-01-01

It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. ‘Iceberg’) and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury. PMID:23451194

Impacts of Low-Flow and Stream-Temperature Changes on Endangered Atlantic Salmon - Current Research

USGS Publications Warehouse

Dudley, Robert W.; Hodgkins, Glenn A.; Letcher, Benjamin H.

2008-01-01

Recent climate studies in New England and the northeastern United States have shown evidence of physical changes over time, including trends toward earlier snowmelt runoff, decreasing river ice, and increasing spring water temperatures. A U.S. Geological Survey (USGS) study funded by the National Global Warming and Wildlife Science Center will be investigating changes in summer low streamflows and stream temperatures and the potential effects of those changes on endangered Atlantic salmon populations. The study also will evaluate management options that would be most likely to mitigate the effects of any changes in streamflow and temperature.

Decreased photosynthetic rate under high temperature in wheat is due to lipid desaturation, oxidation, acylation, and damage of organelles.

PubMed

Djanaguiraman, M; Boyle, D L; Welti, R; Jagadish, S V K; Prasad, P V V

2018-04-05

High temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d. Compared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system. Taken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.

The effects of temperature and aeration on the corrosion of A508III low alloy steel in boric acid solutions at 25-95 °C

NASA Astrophysics Data System (ADS)

Xiao, Qian; Lu, Zhanpeng; Chen, Junjie; Yao, Meiyi; Chen, Zhen; Ejaz, Ahsan

2016-11-01

The effects of temperature, solution composition and dissolved oxygen on the corrosion rate and electrochemical behavior of an A508III low alloy steel in boric acid solution with lithium hydroxide at 25-95 °C are investigated. In aerated solutions, increasing the boric acid concentration increases the corrosion rate and the anodic current density. The corrosion rate in deaerated solutions increases with increasing temperature. A corrosion rate peak value is found at approximately 75 °C in aerated solutions. Increasing temperature increases the oxygen diffusion coefficient, decreases the dissolved oxygen concentration, accelerates the hydrogen evolution reaction, and accelerates both the active dissolution and the film forming reactions. Increasing dissolved oxygen concentration does not significantly affect the corrosion rate at 50 and 60 °C, increases the corrosion rate at 70 and 80 °C, and decreases the corrosion rate at 87.5 and 95 °C in a high concentration boric acid solution with lithium hydroxide.

Effect of pre-dehydration treatment on the in vitro digestibility of starch in cookie.

PubMed

Kawai, Kiyoshi; Kawai, Haruna; Tomoda, Yuka; Matsusaki, Keiko; Hagura, Yoshio

2012-12-01

In order to understand the effect of pre-dehydration on the in vitro digestibility of cookie starch, cookie dough samples were dehydrated by vacuum treatment, and melting temperature (T(m)) of the crystalline amylopectin in the dough, internal temperature and water content of the dough during baking, and non-hydrolysed starch content of the obtained cookies were investigated. The T(m) of crystalline amylopectin increased with decreased water content of the dough, and the result was described as a T(m)-curve. The internal temperature of non-dehydrated dough surpassed the T(m)-curve during baking. Pre-dehydrated dough, on the other hand, always indicated a lower internal temperature than the T(m)-curve. The non-hydrolysed starch content obtained under a given condition increased significantly with a decrease in the initial water content of cookies. This will be because the melting of crystalline amylopectin was prevented, at least partially, during baking. Copyright © 2012 Elsevier Ltd. All rights reserved.

Increased Expression of Escherichia coli Polynucleotide Phosphorylase at Low Temperatures Is Linked to a Decrease in the Efficiency of Autocontrol

PubMed Central

Mathy, N.; Jarrige, A.-C.; Robert-Le Meur, M.; Portier, C.

2001-01-01

Polynucleotide phosphorylase (PNPase) synthesis is translationally autocontrolled via an RNase III-dependent mechanism, which results in a tight correlation between protein level and messenger stability. In cells grown at 18°C, the amount of PNPase is twice that found in cells grown at 30°C. To investigate whether this effect was transcriptional or posttranscriptional, the expression of a set of pnp-lacZ transcriptional and translational fusions was analyzed in cells grown at different temperatures. In the absence of PNPase, there was no increase in pnp-lacZ expression, indicating that the increase in pnp expression occurs at a posttranscriptional level. Other experiments clearly show that increased pnp expression at low temperature is only observed under conditions in which the autocontrol mechanism of PNPase is functional. At low temperature, the destabilizing effect of PNPase on its own mRNA is less efficient, leading to a decrease in repression and an increase in the expression level. PMID:11395447

Increased expression of Escherichia coli polynucleotide phosphorylase at low temperatures is linked to a decrease in the efficiency of autocontrol.

PubMed

Mathy, N; Jarrige, A C; Robert-Le Meur, M; Portier, C

2001-07-01

Polynucleotide phosphorylase (PNPase) synthesis is translationally autocontrolled via an RNase III-dependent mechanism, which results in a tight correlation between protein level and messenger stability. In cells grown at 18 degrees C, the amount of PNPase is twice that found in cells grown at 30 degrees C. To investigate whether this effect was transcriptional or posttranscriptional, the expression of a set of pnp-lacZ transcriptional and translational fusions was analyzed in cells grown at different temperatures. In the absence of PNPase, there was no increase in pnp-lacZ expression, indicating that the increase in pnp expression occurs at a posttranscriptional level. Other experiments clearly show that increased pnp expression at low temperature is only observed under conditions in which the autocontrol mechanism of PNPase is functional. At low temperature, the destabilizing effect of PNPase on its own mRNA is less efficient, leading to a decrease in repression and an increase in the expression level.

Effect of Vacuum Frying on Changes in Quality Attributes of Jackfruit (Artocarpus heterophyllus) Bulb Slices

PubMed Central

Bawa, A. S.; Raju, P. S.

2014-01-01

The effect of frying temperatures and durations on the quality of vacuum fried jackfruit (JF) chips was evaluated. Moisture content and breaking force of JF chips decreased with increase in frying temperature and time during vacuum frying whereas the oil content increased. The frying time for JF chips was found to be 30, 25, and 20 minutes at 80, 90, and 100°C, respectively. JF chips fried at higher temperature resulted in maximum shrinkage (48%). The lightness in terms of hunter L * value decreased significantly (P < 0.05) during frying. Sensory evaluation showed maximum acceptability for JF chips fried at 90°C for 25 min. Frying under vacuum at lower temperatures was found to retain bioactive compounds such as total phenolics, total flavonoids, and total carotenoids in JF chips. Almost 90% of carotenoids were lost from the samples after 30 min of frying at 100°C. PMID:26904648

Changes in leaf epicuticular wax load and its effect on leaf temperature and physiological traits in wheat cultivars (Triticum aestivum L.) exposed to high temperatures during anthesis

USDA-ARS?s Scientific Manuscript database

The physiological functions of epicuticular wax (EW) include reflectance of irradiation and the reduction of water loss. When a plant experiences stressful conditions, most notably, high irradiance and temperature, damage to the photosynthetic apparatus can occur and is signaled by a decrease in the...

Thermal study of the Missouri River in North Dakota using infrared imagery

USGS Publications Warehouse

Crosby, Orlo A.

1971-01-01

The study indicates a marked decrease in water temperature in the Missouri River prior to early fall and a moderate increase in temperature in late fall because of the Lake Sakakawea impoundment. At the present time, thermal additions generated by the powerplants have little effect on the temperature regimen of the Missouri River at high rates of river discharge.

Douglas-fir displays a range of growth responses to ...

EPA Pesticide Factsheets

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 using time series intervention analysis of intra-annual tree-ring width data collected at nine forest stands in western Oregon, USA. The effects of temperature and SNC were similar in importance on tree growth at all sites. Previous-year DPD during the annual drought period was a key factor limiting growth regionally. Winter temperature was more important at high elevation cool sites, whereas summer temperature was more important at warm and dry sites. Growth rate increased with summer temperature to an optimum (Topt) then decreased at higher temperatures. At drier sites, temperature and water affected growth interactively such that Topt decreased with decreasing summer soil moisture. With climate change, growth rates increased at high elevation sites and declined at mid-elevation inland sites since ~1990. Growth response to climate is masked by SNC regionally. We conclude that as temperature rises and precipitation patterns shift towards wetter winters and drier summers, Douglas-fir will experience greater temperature and water stress and an increase in severity of SNC. By the end of the 21st century, climate models predict hotter, drier summers and warmer, wetter winters in the Pac

Elevated temperature and CO(2) concentration effects on xylem anatomy of Scots pine.

PubMed

Kilpeläinen, Antti; Gerendiain, Ane Zubizarreta; Luostarinen, Katri; Peltola, Heli; Kellomäki, Seppo

2007-09-01

We studied the effects of elevated temperature and carbon dioxide concentration ([CO(2)]) alone and together on wood anatomy of 20-year-old Scots pine (Pinus sylvestris L.) trees. The study was conducted in 16 closed chambers, providing a factorial combination of two temperature regimes and two CO(2) concentrations (ambient and elevated), with four trees in each treatment. The climate scenario included a doubling of [CO(2)] and a corresponding increase of 2-6 degrees C in temperature at the site depending on the season. Anatomical characteristics analyzed were annual earlywood, latewood and ring widths, intra-ring wood densities (earlywood, latewood and mean wood density), tracheid width, length, wall thickness, lumen diameter, wall thickness:lumen diameter ratio and mass per unit length (coarseness), and numbers of rays, resin canals and tracheids per xylem cross-sectional area. Elevated [CO(2)] increased ring width in four of six treatment years; earlywood width increased in the first two years and latewood width in the third year. Tracheid walls in both the earlywood and latewood tended to become thicker over the 6-year treatment period when temperature or [CO(2)] was elevated alone, whereas in the combined treatment they tended to become thinner relative to the tracheids of trees grown under ambient conditions. Latewood tracheid lumen diameters were larger in all the treatments relative to ambient conditions over the 6-year period, whereas lumen diameters in earlywood increased only in response to elevated [CO(2)] and were 3-6% smaller in the treatments with elevated temperature than in ambient conditions. Tracheid width, length and coarseness were greater in trees grown in elevated than in ambient temperature. The number of resin canals per mm(2) decreased in the elevated [CO(2)] treatment and increased in the elevated temperature treatments relative to ambient conditions. The treatments decreased the number of rays and tracheids per mm(2) of cross-sectional area, the greatest decrease occurring in the elevated [CO(2)] treatment. It seemed that xylem anatomy was affected more by elevated temperature than by elevated [CO(2)] and that the effects of temperature were confined to the earlywood.

Evidence of Aerosol's Influence on Climate from Beijing Olympics

NASA Astrophysics Data System (ADS)

Chen, S.; Fu, Q.; Huang, J.; Ge, J.; Su, J.

2009-12-01

Air pollution is a difficult problem during the process of industrialization in most developing countries. In China, the main air pollutants are inhaled aerosol particles. Because of the extremely high loading and rapid development, Beijing became a heavily polluted city, with a population of more than 16 million. The 2008 Olympic Summer Games provided a unique opportunity for the study of climate effects of aerosols due to many measurements taken to fight pollution caused by industrialization and economic growth.Surface temperature is the most intuitive meteorological factor and easy to get. Therefore, aerosol’s radiative effects on regional climate can be known by studying the relationship between aerosols and surface temperature in Beijing city in August 2008. However, many factors can affect the surface temperature and cloud is considered as a very important meteorological element in radiation balance. In order to remove the impact of clouds on surface temperature, here the ground temperature in clear sky days (when cloud cover is less than 2) are selected. Aerosol data from the MODerate resolution Imaging Spectroradiometer (MODIS) onboard the Earth Observing System (EOS) Aqua shows that aerosol concentration decreased significantly in the area of Olympic venues in August 2008. Meanwhile, the ground-based observation data shows the surface temperature during the day (14LT) and night (02LT) in August 2008 is higher and lower than the mean temperature in August from 2002 to 2008, respectively. It is discovered that the distribution of satellite-retrieved aerosol optical Depth (AOD) in the whole area of Beijing in August of 2003 and 2004 is similar to that in 2008. We chosen four meteorological stations to analyze surface temperature and found that the diurnal changes of surface temperature are consistent with that in August of 2003, 2004 and 2008. Meanwhile, the decrease of AOD in the area of Olympic venues in August 2008 leads to the increase of precipitation, and furthermore produces more water vapor content with previous years. The effect of water vapor increase an asymmetric departure from the normal during the day and night and make the increase of daily temperature range caused by the decrease of aerosol concentration is not obvious in Beijing Olympic venues in August 2008.

Preparation of high-strength Al-Mg-Si-Cu-Fe alloy via heat treatment and rolling

NASA Astrophysics Data System (ADS)

Liu, Chong-yu; Yu, Peng-fei; Wang, Xiao-ying; Ma, Ming-zhen; Liu, Ri-ping

2014-07-01

An Al-Mg-Si-Cu-Fe alloy was solid-solution treated at 560°C for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180°C. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420°C, and then increased; the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180°C rolling water-quenched alloy were also improved by the presence of β″ phase. Above 420°C, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.

Temperature dependence of water-water and ion-water correlations in bulk water and electrolyte solutions probed by femtosecond elastic second harmonic scattering

NASA Astrophysics Data System (ADS)

Chen, Yixing; Dupertuis, Nathan; Okur, Halil I.; Roke, Sylvie

2018-06-01

The temperature dependence of the femtosecond elastic second harmonic scattering (fs-ESHS) response of bulk light and heavy water and their electrolyte solutions is presented. We observe clear temperature dependent changes in the hydrogen (H)-bond network of water that show a decrease in the orientational order of water with increasing temperature. Although D2O has a more structured H-bond network (giving rise to more fs-ESHS intensity), the relative temperature dependence is larger in H2O. The changes are interpreted in terms of the symmetry of H-bonds and are indicators of nuclear quantum effects. Increasing the temperature in electrolyte solutions decreases the influence of the total electrostatic field from ions on the water-water correlations, as expected from Debye-Hückel theory, since the Debye length becomes longer. The effects are, however, 1.9 times (6.3 times) larger than those predicted for H2O (D2O). Since fs-ESHS responses can be computed from known molecular coordinates, our observations provide a unique opportunity to refine quantum mechanical models of water.

Investigations on Heat Treatment of a High-Speed Steel Roll

NASA Astrophysics Data System (ADS)

Fu, Hanguang; Qu, Yinhu; Xing, Jiandong; Zhi, Xiaohui; Jiang, Zhiqiang; Li, Mingwei; Zhang, Yi

2008-08-01

High-carbon high-speed steels (HSS) are very abrasion-resistant materials primarily due to their high hardness MC-type carbide and high hardness martensitic matrix. The effects of quenching and tempering treatment on the microstructure, mechanical properties, and abrasion resistance of centrifugal casting high-carbon HSS roll were studied. Different microstructures and mechanical properties were obtained after the quenching and tempering temperatures of HSS roll were changed. With air-cooling and sodium silicate solution cooling, when the austenitizing temperature reaches 1273 K, the metallic matrix all transforms into the martensite. Afterwards, the eutectic carbides dissolve into the metallic matrix and their continuous network distribution changes into the broken network. The second hardening temperature of high-carbon HSS roll is around 793 K. No significant changes in tensile strength and elongation percentage are observed unless the tempering temperature is beyond 753 K. The tensile strength increases obviously and the elongation percentage decreases slightly beyond 753 K. However, the tensile strength decreases and the elongation percentage increases when the tempering temperature exceeds 813 K. When the tempering temperature excels 773 K, the impact toughness has a slight decrease. Tempering at 793-813 K, high-carbon HSS roll presents excellent abrasion resistance.

Effect of concentration and temperature on the rheological behavior of collagen solution.

PubMed

Lai, Guoli; Li, Yang; Li, Guoying

2008-04-01

Dynamic viscoelastic properties of collagen solutions with concentrations of 0.5-1.5% (w/w) were characterized by means of oscillatory rheometry at temperatures ranging from 20 to 32.5 degrees C. All collagen solutions showed a shear-thinning flow behavior. The complex viscosity exhibited an exponential increase and the loss tangent decreased with the increase of collagen concentration (C(COL)) when the C(COL)> or =0.75%. Both storage modulus (G') and loss modulus (G'') increased with the increase of frequency and concentration, but decreased with the increase of temperature and behaved without regularity at 32.5 degrees C. The relaxation times decreased with the increase of temperature for 1.0% collagen solution. According to a three-zone model, dynamic modulus of collagen solutions showed terminal-zone and plateau-zone behavior when C(COL) was no more than 1.25% or the stated temperature was no more than 30 degrees C. The concentrated solution (1.5%) behaved being entirely in plateau zone. An application of the time-temperature superposition (TTS) allowed the construction of master curve and an Arrhenius-type TTS principle was used to yield the activation energy of 161.4 kJ mol(-1).

Ghrelin-induced hypothermia: A Physiological basis but no clinical risk

PubMed Central

Wiedmer, Petra; Strasser, Florian; Horvath, Tamas L.; Blum, David; DiMarchi, Richard; Lutz, Thomas; Schürmann, Annette; Joost, Hans-Georg; Tschöp, Matthias H.; Tong, Jenny

2011-01-01

Ghrelin increases food intake and decreases energy expenditure, promoting a positive energy balance. We observed a single case of serious hypothermia during sustained ghrelin treatment in a male subject, suggesting that ghrelin may play a role in the regulation of body temperature. We therefore investigated the effect of ghrelin treatment on body temperature in rodents and humans under controlled conditions. Intriguingly, we could demonstrate ghrelin binding in axon terminals of the medial preoptic area of the hypothalamus located in the vicinity of cold-sensitive neurons. This localization of ghrelin receptors provides a potential anatomical basis for the regulation of body temperature by ghrelin. However, our follow-up studies also indicated that neither a chronic i.c.v. application of ghrelin in rats, nor a single s.c. injection under cold exposure in mice resulted in a relevant decrease in body core temperature. In addition, a four-hour intravenous ghrelin infusion did not decrease body surface temperature in healthy humans. We concluded that while there is a theoretical molecular basis for ghrelin to modify body temperature in mammals, its magnitude is irrelevant under physiologic circumstances. Hypothermia is not likely to represent a serious risk associated with this agent and pathway. PMID:21513721

Infrared drying of strawberry.

PubMed

Adak, Nafiye; Heybeli, Nursel; Ertekin, Can

2017-03-15

The effects of different drying conditions, such as infrared power, drying air temperature and velocity, on quality of strawberry were evaluated. Drying time decreased with increased infrared power, air temperature and velocity. An increase in power from 100W to 300W, temperature from 60 to 80°C and velocity from 1.0m.s -1 to 2.0m.s -1 decreased fruit color quality index. For total phenol and anthocyanin content, 300W, 60°C, and 1.0m.s -1 were superior to the other experimental conditions. The drying processes increased N, P and K and decreased Ca, Mg, Fe, Mn, Zn and Cu contents. The optimal conditions to preserve nutrients in infrared drying of strawberry were 200W, 100°C and 1.5m.s -1 . Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantifying the effects of wildfire on changes in soil properties by surface burning of soils from the Boulder Creek Critical Zone Observatory

USGS Publications Warehouse

Wieting, Celeste; Ebel, Brian A.; Singha, Kamini

2017-01-01

Study regionThis study used intact soil cores collected at the Boulder Creek Critical Zone Observatory near Boulder, Colorado, USA to explore fire impacts on soil properties.Study focusThree soil scenarios were considered: unburned control soils, and low- and high-temperature burned soils. We explored simulated fire impacts on field-saturated hydraulic conductivity, dry bulk density, total organic carbon, and infiltration processes during rainfall simulations.New hydrological insights for the regionSoils burned to high temperatures became more homogeneous with depth with respect to total organic carbon and bulk density, suggesting reductions in near-surface porosity. Organic matter decreased significantly with increasing soil temperature. Tension infiltration experiments suggested a decrease in infiltration rates from unburned to low-temperature burned soils, and an increase in infiltration rates in high-temperature burned soils. Non-parametric statistical tests showed that field-saturated hydraulic conductivity similarly decreased from unburned to low-temperature burned soils, and then increased with high-temperature burned soils. We interpret these changes result from the combustion of surface and near-surface organic materials, enabling water to infiltrate directly into soil instead of being stored in the litter and duff layer at the surface. Together, these results indicate that fire-induced changes in soil properties from low temperatures were not as drastic as high temperatures, but that reductions in surface soil water repellency in high temperatures may increase infiltration relative to low temperatures.

Reactive oxygen species scavenger N-acetyl cysteine reduces methamphetamine-induced hyperthermia without affecting motor activity in mice

PubMed Central

Sanchez-Alavez, Manuel; Bortell, Nikki; Galmozzi, Andrea; Conti, Bruno; Marcondes, Maria Cecilia G.

2014-01-01

Hyperthermia is a potentially lethal side effect of Methamphetamine (Meth) abuse, which involves the participation of peripheral thermogenic sites such as the Brown Adipose Tissue (BAT). In a previous study we found that the anti-oxidant N-acetyl cysteine (NAC) can prevent the high increase in temperature in a mouse model of Meth-hyperthermia. Here, we have further explored the ability of NAC to modulate Meth-induced hyperthermia in correlation with changes in BAT. We found that NAC treatment in controls causes hypothermia, and, when administered prior or upon the onset of Meth-induced hyperthermia, can ameliorate the temperature increase and preserve mitochondrial numbers and integrity, without affecting locomotor activity. This was different from Dantrolene, which decreased motor activity without affecting temperature. The effects of NAC were seen in spite of its inability to recover the decrease of mitochondrial superoxide induced in BAT by Meth. In addition, NAC did not prevent the Meth-induced decrease of BAT glutathione. Treatment with S-adenosyl-L-methionine, which improves glutathione activity, had an effect in ameliorating Meth-induced hyperthermia, but also modulated motor activity. This suggests a role for the remaining glutathione for controlling temperature. However, the mechanism by which NAC operates is independent of glutathione levels in BAT and specific to temperature. Our results show that, in spite of the absence of a clear mechanism of action, NAC is a pharmacological tool to examine the dissociation between Meth-induced hyperthermia and motor activity, and a drug of potential utility in treating the hyperthermia associated with Meth-abuse. PMID:26346736

Correlation of Coronal Plasma Properties and Solar Magnetic Field in a Decaying Active Region

NASA Technical Reports Server (NTRS)

Ko, Yuan-Kuen; Young, Peter R.; Muglach, Karin; Warren, Harry P.; Ugarte-Urra, Ignacio

2016-01-01

We present the analysis of a decaying active region observed by the EUV Imaging Spectrometer on Hinode during 2009 December 7-11. We investigated the temporal evolution of its structure exhibited by plasma at temperatures from 300,000 to 2.8 million degrees, and derived the electron density, differential emission measure, effective electron temperature, and elemental abundance ratios of Si/S and Fe/S (as a measure of the First Ionization Potential (FIP) Effect). We compared these coronal properties to the temporal evolution of the photospheric magnetic field strength obtained from the Solar and Heliospheric Observatory Michelson Doppler Imager magnetograms. We find that, while these coronal properties all decreased with time during this decay phase, the largest change was at plasma above 1.5 million degrees. The photospheric magnetic field strength also decreased with time but mainly for field strengths lower than about 70 Gauss. The effective electron temperature and the FIP bias seem to reach a basal state (at 1.5 x 10(exp 6) K and 1.5, respectively) into the quiet Sun when the mean photospheric magnetic field (excluding all areas <10 G) weakened to below 35 G, while the electron density continued to decrease with the weakening field. These physical properties are all positively correlated with each other and the correlation is the strongest in the high-temperature plasma. Such correlation properties should be considered in the quest for our understanding of how the corona is heated. The variations in the elemental abundance should especially be considered together with the electron temperature and density.

[Effects of water stress and temperature on gas exchange and chlorophyll fluorescence of Sinocalycanthus chinensis leaves].

PubMed

Ke, Shi-sheng; Jin, Ze-xin

2008-01-01

Sinocalycanthus chinensis is an endangered species in Sinocalycanthus, and only distributed in Zhejiang Province of China. This paper studied the photosynthetic responses of 2-year-old pot-cultured S. chinensis to different levels of water stress and temperature. The results indicated that under mild and moderate water stress, the net photosynthetic rate (Pn) of S. chinensis leaves was decreased to 92.3% and 74.3% of the control, respectively, which was mainly attributed to stomatal limitation; and under severe water stress, the Pn was decreased to 44.4% of the control, which might be mainly linked to non-stomatal limitation. The appropriate temperature for S. chinensis photosynthesis was from 20 degrees C to 28 degrees C. At 39 degrees C, the Pn, water use efficiency (WUE), and maximal photochemistry efficiency (Fv/Fm) were decreased significantly, while the dark respiration rate (Rd) and transpiration rate (Tr) were enhanced significantly. With increasing water stress and temperature, some photosynthetic parameters including light saturation point (LSP), apparent quantum yield (AQY) and maximal CO2 assimilation rate (Pmax) decreased to certain extents, while light compensation point (LCP) increased, suggesting that both severe water stress and higher temperature were the important environmental factors affecting the survival of S. chinensis.

Effect of irrigation fluid temperature on body temperature during arthroscopic elbow surgery in dogs.

PubMed

Thompson, K R; MacFarlane, P D

2013-01-01

This prospective randomised clinical trial evaluated the effect of warmed irrigation fluid on body temperature in anaesthetised dogs undergoing arthroscopic elbow surgery. Nineteen dogs undergoing elbow arthroscopy were included in the study and were randomly allocated to one of two groups. Group RT received irrigation fluid at room temperature (RT) while dogs in group W received warmed (W) irrigation fluid (36°C). A standardised patient management and anaesthetic protocol was used and body temperature was measured at four time points; (T1) pre-anaesthetic examination, (T2) arrival into theatre, (T3) end of surgery and (T4) arrival into recovery. There was no significant difference in body temperature at any time point between the groups. The mean overall decrease in body temperature between pre-anaesthetic examination (T1) and return to the recovery suite (T4) was significant in both groups, with a fall of 1.06±0.58°C (p<0.001) in group RT and 1.53±0.76°C (p<0.001) group W. There was no significant difference between the groups. At the end of surgery (T3) 4/19 (21.1%) of dogs were hypothermic (<37°C). The addition of warmed irrigation fluids to a temperature management protocol in dogs undergoing elbow arthroscopy during general anaesthesia did not lead to decreased temperature losses.

Effect of irrigation fluid temperature on body temperature during arthroscopic elbow surgery in dogs

PubMed Central

Thompson, K.R.; MacFarlane, P.D.

2013-01-01

This prospective randomised clinical trial evaluated the effect of warmed irrigation fluid on body temperature in anaesthetised dogs undergoing arthroscopic elbow surgery. Nineteen dogs undergoing elbow arthroscopy were included in the study and were randomly allocated to one of two groups. Group RT received irrigation fluid at room temperature (RT) while dogs in group W received warmed (W) irrigation fluid (36°C). A standardised patient management and anaesthetic protocol was used and body temperature was measured at four time points; (T1) pre-anaesthetic examination, (T2) arrival into theatre, (T3) end of surgery and (T4) arrival into recovery. There was no significant difference in body temperature at any time point between the groups. The mean overall decrease in body temperature between pre-anaesthetic examination (T1) and return to the recovery suite (T4) was significant in both groups, with a fall of 1.06±0.58°C (p<0.001) in group RT and 1.53±0.76°C (p<0.001) group W. There was no significant difference between the groups. At the end of surgery (T3) 4/19 (21.1%) of dogs were hypothermic (<37°C). The addition of warmed irrigation fluids to a temperature management protocol in dogs undergoing elbow arthroscopy during general anaesthesia did not lead to decreased temperature losses. PMID:26623323

Circulatory failure during severe hyperthermia in dog.

PubMed

Miki, K; Morimoto, T; Nose, H; Itoh, T; Yamada, S

1983-01-01

The effect of acute hyperthermia on circulatory function was studied in 6 mongrel dogs. At a core temperature of about 40 degrees C, central venous pressure and stroke volume were maintained at almost normal level. Cardiac output significantly increased (26 ml/(kg . min)) while systemic vascular resistance significantly decreased (1.2 mmHg . sec/ml). In addition, significant decrease in vascular compliance by 40% was observed. When body temperature was raised further (severe hyperthermia), an abrupt fall of arterial pressure was observed at the rectal temperature of about 41-42 degrees C. Concomitant decreases in central venous pressure (3 mmHg), stroke volume (2.1 ml/beat) and cardiac output (29 ml/(kg . min)) were observed while heart rate increased (48 beats/min). These results suggest that the decrease in cardiac output during severe hyperthermia is due to the fall of central venous pressure, and the fall was attributed to the increase in unstressed vascular volume of systemic circulation due to the heat-induced cutaneous vasodilation. The observed decrease in systemic vascular compliance is considered to have a significant role in the maintenance of central venous pressure under hyperthermia.

Effect of ambient temperature and relative humidity on interfacial temperature during early stages of drop evaporation.

PubMed

Fukatani, Yuki; Orejon, Daniel; Kita, Yutaku; Takata, Yasuyuki; Kim, Jungho; Sefiane, Khellil

2016-04-01

Understanding drop evaporation mechanisms is important for many industrial, biological, and other applications. Drops of organic solvents undergoing evaporation have been found to display distinct thermal patterns, which in turn depend on the physical properties of the liquid, the substrate, and ambient conditions. These patterns have been reported previously to be bulk patterns from the solid-liquid to the liquid-gas drop interface. In the present work the effect of ambient temperature and humidity during the first stage of evaporation, i.e., pinned contact line, is studied paying special attention to the thermal information retrieved at the liquid-gas interface through IR thermography. This is coupled with drop profile monitoring to experimentally investigate the effect of ambient temperature and relative humidity on the drop interfacial thermal patterns and the evaporation rate. Results indicate that self-generated thermal patterns are enhanced by an increase in ambient temperature and/or a decrease in humidity. The more active thermal patterns observed at high ambient temperatures are explained in light of a greater temperature difference generated between the apex and the edge of the drop due to greater evaporative cooling. On the other hand, the presence of water humidity in the atmosphere is found to decrease the temperature difference along the drop interface due to the heat of adsorption, absorption and/or that of condensation of water onto the ethanol drops. The control, i.e., enhancement or suppression, of these thermal patterns at the drop interface by means of ambient temperature and relative humidity is quantified and reported.

Temperature and food quantity effects on the harpacticoid copepod Nitocra spinipes: Combining in vivo bioassays with population modeling

PubMed Central

Bui, Thuy T.; Lundström Belleza, Elin; Brinkmann, Markus; Hollert, Henner; Breitholtz, Magnus

2017-01-01

The harpacticoid copepod Nitocra spinipes has become a popular model species for toxicity testing over the past few decades. However, the combined influence of temperature and food shortage, two climate change-related stressors, has never been assessed in this species. Consequently, effects of three temperatures (15, 20 and 25°C) and six food regimes (between 0 and 5 × 105 algal cells/mL) on the life cycle of N. spinipes were examined in this study. Similarly to other copepod species, development times and brood sizes decreased with rising temperatures. Mortality was lowest in the 20°C temperature setup, indicating a close-by temperature optimum for this species. Decreasing food concentrations led to increased development times, higher mortality and a reduction in brood size. A sex ratio shift toward more females per male was observed for increasing temperatures, while no significant relationship with food concentration was found. Temperature and food functions for each endpoint were integrated into an existing individual-based population model for N. spinipes which in the future may serve as an extrapolation tool in environmental risk assessment. The model was able to accurately reproduce the experimental data in subsequent verification simulations. We suggest that temperature, food shortage, and potentially other climate change-related stressors should be considered in environmental risk assessment of chemicals to account for non-optimal exposure conditions that may occur in the field. Furthermore, we advocate combining in vivo bioassays with population modeling as a cost effective higher tier approach to assess such considerations. PMID:28334000

Room temperature spin valve effect in NiFe/WS2/Co junctions

PubMed Central

Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Siddique, Salma; Khan, Muhammad Farooq; Ramay, Shahid Mahmood

2016-01-01

The two-dimensional (2D) layered electronic materials of transition metal dichalcogenides (TMDCs) have been recently proposed as an emerging canddiate for spintronic applications. Here, we report the exfoliated single layer WS2-intelayer based spin valve effect in NiFe/WS2/Co junction from room temperature to 4.2 K. The ratio of relative magnetoresistance in spin valve effect increases from 0.18% at room temperature to 0.47% at 4.2 K. We observed that the junction resistance decreases monotonically as temperature is lowered. These results revealed that semiconducting WS2 thin film works as a metallic conducting interlayer between NiFe and Co electrodes. PMID:26868638

Room temperature spin valve effect in NiFe/WS₂/Co junctions.

PubMed

Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Siddique, Salma; Khan, Muhammad Farooq; Ramay, Shahid Mahmood

2016-02-12

The two-dimensional (2D) layered electronic materials of transition metal dichalcogenides (TMDCs) have been recently proposed as an emerging canddiate for spintronic applications. Here, we report the exfoliated single layer WS2-intelayer based spin valve effect in NiFe/WS2/Co junction from room temperature to 4.2 K. The ratio of relative magnetoresistance in spin valve effect increases from 0.18% at room temperature to 0.47% at 4.2 K. We observed that the junction resistance decreases monotonically as temperature is lowered. These results revealed that semiconducting WS2 thin film works as a metallic conducting interlayer between NiFe and Co electrodes.

The effects of temperature, organic matter and time-dependency on rheological properties of dry anaerobic digested swine manure.

PubMed

Liu, Gang-Jin; Liu, Yi; Wang, Zhi-Yong; Lei, Yun-Hui; Chen, Zi-Ai; Deng, Liang-Wei

2015-04-01

An efficient way to avoid the pollution of swine wastewater is the application of dry anaerobic digestion, which needs rheological parameter for stirring and pipe designing. The rheological properties of this kind of sludge have been studied for many decades, yet their effects only solid concentration has been investigated widely. In this paper, the influences of temperature, organic and time-dependency on the efficiency of anaerobic digested swine manure were studied. The viscosity decreased with temperature arranged from 10 to 60 °C which caused increase in protein from 7.18 to 8.49 g/kg. 60 °C can make the digested swine manure with TS from 16.6% to 21.5% reach to the same rheology state. The added peptone decreased the viscosity because of its function of water-reducing admixture and air entraining mixture. Time-dependent experiment showed the decrease of shear stress over time. The first and the second yield stress of dry anaerobic digested swine manure were evaluated through time-dependent model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Performance benefits from pulsed laser heating in heat assisted magnetic recording

NASA Astrophysics Data System (ADS)

Xu, B. X.; Cen, Z. H.; Goh, J. H.; Li, J. M.; Toh, Y. T.; Zhang, J.; Ye, K. D.; Quan, C. G.

2014-05-01

Smaller cross track thermal spot size and larger down track thermal gradient are desired for increasing the density of heat assisted magnetic recording. Both parameters are affected significantly by the thermal energy accumulation and diffusion in the recording media. Pulsed laser heating is one of the ways to reduce the thermal diffusion. In this paper, we describe the benefits from the pulsed laser heating such as the dependences of the cross track thermal width, down track thermal gradient, the required laser pulse/average powers, and the transducer temperature rise on the laser pulse width at different media thermal properties. The results indicate that as the pulse width decreases, the thermal width decreases, the thermal gradient increases, the required pulse power increases and the average power decreases. For shorter pulse heating, the effects of the medium thermal properties on the thermal performances become weaker. This can greatly relax the required thermal properties of the media. The results also show that the pulsed laser heating can effectively reduce the transducer temperature rise and allow the transducer to reach its "dynamically" stable temperature more quickly.

Intra-operative fluid warming in elective caesarean section: a blinded randomised controlled trial.

PubMed

Woolnough, M; Allam, J; Hemingway, C; Cox, M; Yentis, S M

2009-10-01

We assessed the effect of warming intravenous fluids during elective caesarean section under combined spinal-epidural anaesthesia in a blinded, randomised controlled trial. Seventy-five women having elective caesarean section were randomly assigned to receive all intravenous fluids at room temperature, or heated in a cabinet set at 45 degrees C or via a Hotline fluid warmer (Smiths Medical International Ltd, Watford, Herts, UK). After 10 mL/kg crystalloid preload, combined spinal-epidural anaesthesia was performed. Core and ambient temperatures, thermal comfort and shivering were measured every 15 min thereafter. The primary outcome was the temperature at 60 min. Temperature decreased in all groups. Although the temperature decrease at 60 min was similar in the heated cabinet and Hotline groups, the room temperature group exhibited a greater decrease [difference 0.4 degrees C (95% CI 0.2-0.6 degrees C); P=0.015]. More women felt cold in the room temperature group (8: 32%) than in the heated cabinet set (3: 12%) and Hotline (1: 4%) groups (P=0.02), but the incidence of shivering was similar: 11 (44%), 9 (36%) and 7 (28%) respectively. Apgar scores and neonatal cord gases were similar. Warming intravenous fluids mitigates the decrease in maternal temperature during elective caesarean section under combined spinal-epidural anaesthesia and improves thermal comfort, but does not affect shivering. Intravenous fluids should be warmed routinely in elective caesarean section, especially for cases of expected long duration, but the use of pre-warmed fluids is as efficient and cheaper than using a Hotline fluid warmer.

Spatio-temporal Trends of Climate Variability in North Carolina

NASA Astrophysics Data System (ADS)

Sayemuzzaman, Mohammad

Climatic trends in spatial and temporal variability of maximum temperature (Tmax), minimum temperature (Tmin), mean temperature (Tmean) and precipitation were evaluated for 249 ground-based stations in North Carolina for 1950-2009. The Mann-Kendall (MK), the Theil-Sen Approach (TSA) and the Sequential Mann-Kendall (SQMK) tests were applied to quantify the significance of trend, magnitude of trend and the trend shift, respectively. The lag-1 serial correlation and double mass curve techniques were used to address the data independency and homogeneity. The pre-whitening technique was used to eliminate the effect of auto correlation of the data series. The difference between minimum and maximum temperatures, and so the diurnal temperature range (DTR), at some stations was found to be decreasing on both an annual and a seasonal basis, with an overall increasing trend in the mean temperature. For precipitation, a statewide increasing trend in fall (highest in November) and decreasing trend in winter (highest in February) were detected. No pronounced increasing/decreasing trends were detected in annual, spring, and summer precipitation time series. Trend analysis on a spatial scale (for three physiographic regions: mountain, piedmont and coastal) revealed mixed results. Coastal zone exhibited increasing mean temperature (warming) trend as compared to other locations whereas mountain zone showed decreasing trend (cooling). Three main moisture components (precipitation, total cloud cover, and soil moisture) and the two major atmospheric circulation modes (North Atlantic Oscillation and Southern Oscillation) were used for correlative analysis purposes with the temperature (specifically with DTR) and precipitation trends. It appears that the moisture components are associated with DTR more than the circulation modes in North Carolina.

Effects of cold and hot temperature on dehydration: a mechanism of cardiovascular burden.

PubMed

Lim, Youn-Hee; Park, Min-Seon; Kim, Yoonhee; Kim, Ho; Hong, Yun-Chul

2015-08-01

The association between temperature (cold or heat) and cardiovascular mortality has been well documented. However, few studies have investigated the underlying mechanism of the cold or heat effect. The main goal of this study was to examine the effect of temperature on dehydration markers and to explain the pathophysiological disturbances caused by changes of temperature. We investigated the relationship between outdoor temperature and dehydration markers (blood urea nitrogen (BUN)/creatinine ratio, urine specific gravity, plasma tonicity and haematocrit) in 43,549 adults from Seoul, South Korea, during 1995-2008. We used piece-wise linear regression to find the flexion point of apparent temperature and estimate the effects below or above the apparent temperature. Levels of dehydration markers decreased linearly with an increase in the apparent temperature until a point between 22 and 27 °C, which was regarded as the flexion point of apparent temperature, and then increased with apparent temperature. Because the associations between temperature and cardiovascular mortality are known to be U-shaped, our findings suggest that temperature-related changes in hydration status underlie the increased cardiovascular mortality and morbidity during high- or low-temperature conditions.

Effect of temperature on the orthodontic clinical applications of niti closed-coil springs

PubMed Central

Espinar-Escalona, Eduardo; Llamas-Carreras, José M.; Barrera-Mora, José M.; Abalos-Lasbrucci, Camilo

2013-01-01

NiTi spring coils were used to obtain large deformation under a constant force. The device consists on a NiTi coil spring, superelastic at body temperature, in order to have a stress plateau during the austenitic retransformation during the unloading. The temperature variations induced changes in the spring force. Objectives: The aim of this study is to investigate the effect of the temperature variations in the spring forces and corrosion behaviour simulating the ingestion hot/cold drinks and food. Study Design: The springs were subjected to a tensile force using universal testing machine MTS-Adamel (100 N load cell). All tests were performed in artificial saliva maintained at different temperatures. The corrosion tests were performed according to the ISO-standard 10993-15:2000. Results: The increase in temperature of 18oC induced an increase in the spring force of 30%. However, when the temperature returns to 37oC the distraction force recovers near the initial level. After cooling down the spring to 15oC, the force decreased by 46%. This investigation show as the temperature increase, the corrosion potential shifts towards negative values and the corrosion density is rising. Conclusions: The changes of the temperatures do not modify the superelastic behaviour of the NiTi closed-coil springs. The corrosion potential of NiTi in artificial saliva is decreasing by the rise of the temperatures. Key words:Superelasticity, NiTi, springs, orthodontic, coils, recovery, temperature. PMID:23722142

The Effect of Insertion Technique on Temperatures for Standard and Self-Drilling External Fixation Pins.

PubMed

Manoogian, Sarah; Lee, Adam K; Widmaier, James C

2017-08-01

No studies have assessed the effects of parameters associated with insertion temperature in modern self-drilling external fixation pins. The current study assessed how varying the presence of irrigation, insertion speed, and force impacted the insertion temperatures of 2 types of standard and self-drilling external fixation half pins. Seventy tests were conducted with 10 trials for 4 conditions on self-drilling pins, and 3 conditions for standard pins. Each test used a thermocouple inside the pin to measure temperature rise during insertion. Adding irrigation to the standard pin insertion significantly lowered the maximum temperature (P <0.001). Lowering the applied force for the standard pin did not have a significant change in temperature rise. Applying irrigation during the self-drilling pin tests dropped average rise in temperature from 151.3 ± 21.6°C to 124.1 ± 15.3°C (P = 0.005). When the self-drilling pin insertion was decreased considerably from 360 to 60 rpm, the temperature decreased significantly from 151.3 ± 21.6°C to 109.6 ± 14.0°C (P <0.001). When the force applied increased significantly, the corresponding self-drilling pin temperature increase was not significant. The standard pin had lower peak temperatures than the self-drilling pin for all conditions. Moreover, slowing down the insertion speed and adding irrigation helped mitigate the temperature increase of both pin types during insertion.

Physiological acclimation of the green tidal alga Ulva prolifera to a fast-changing environment.

PubMed

Wu, Hailong; Gao, Guang; Zhong, Zhihai; Li, Xinshu; Xu, Juntian

2018-06-01

To aid early warning and prevent the outbreak of green tides in the Yellow Sea, both the growth and photosynthetic performance of Ulva prolifera were studied after culture in different temperatures (18, 22, and 26 °C) and light intensities (44, 160, and 280 μmol m -2 ·s -1 ). Furthermore, their instantaneous net photosynthetic performance (INPP) was studied to determine the resulting environmental acclimation. The relative growth rates of U. prolifera significantly decreased in response to increasing temperature, while they increased with increasing light intensity. Culture at higher light intensities significantly increased INPP, while higher temperatures decreased the INPP. Culture at lower temperatures lowered INPP, while increased growth temperature increased the effect. These results suggest that high temperatures during the cold season inhibited U. prolifera growth. However, low temperatures during the warm season increase biomass and may cause a large-scale green tide. These results help to understand the correlation between U. prolifera blooms and extreme weather. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of temperature on the ground state of a strongly-coupling magnetic polaron and mean phonon number in RbCl quantum pseudodot

NASA Astrophysics Data System (ADS)

Sun, Yong; Ding, Zhao-Hua; Xiao, Jing-Lin

2016-07-01

On the condition of strong electron-LO phonon coupling in a RbCl quantum pseudodot (QPD), the ground state energy and the mean number of phonons are calculated by using the Pekar variational method and quantum statistical theory. The variations of the ground state energy and the mean number with respect to the temperature and the cyclotron frequency of the magnetic field are studied in detail. We find that the absolute value of the ground state energy increases (decreases) with increasing temperature when the temperature is in the lower (higher) temperature region, and that the mean number increases with increasing temperature. The absolute value of the ground state energy is a decreasing function of the cyclotron frequency of the magnetic field whereas the mean number is an increasing function of it. We find two ways to tune the ground state energy and the mean number: controlling the temperature and controlling the cyclotron frequency of the magnetic field.

Effects of environmental temperature on the dynamics of ichthyophoniasis in Juvenile Pacific Herring (Clupea pallasii)

USGS Publications Warehouse

Gregg, J.L.; Vollenweider, Johanna J.; Grady, C.A.; Heintz, R.A.; Hershberger, P.K.

2011-01-01

The effects of temperature and infection by Ichthyophonus were examined in juvenile Pacific herring (Clupea pallasii) maintained under simulated overwinter fasting conditions. In addition to defining parameters for a herring bioenergetics model (discussed in Vollenweider et al. this issue), these experiments provided new insights into factors influencing the infectivity and virulence of the parasite Ichthyophonus. In groups of fish with established disease, temperature variation had little effect on disease outcome. Ichthyophonus mortality outpaced that resulting from starvation alone. In newly infected fish, temperature variation significantly changed the mortality patterns related to disease. Both elevated and lowered temperatures suppressed disease-related mortality relative to ambient treatments. When parasite exposure dose decreased, an inverse relationship between infection prevalence and temperature was detected. These findings suggest interplay between temperature optima for parasite growth and host immune function and have implications for our understanding of how Ichthyophonus infections are established in wild fish populations.

The effects of fasting on swimming performance in juvenile qingbo (Spinibarbus sinensis) at two temperatures.

PubMed

Pang, Xu; Yuan, Xing-Zhong; Cao, Zhen-Dong; Fu, Shi-Jian

2014-05-01

We measured the following variables to investigate the effects of fasting and temperature on swimming performance in juvenile qingbo (Spinibarbus sinensis): the critical swimming speed (Ucrit), resting metabolic rate (ṀO2rest) and active metabolic rate (ṀO2active) of fish fasting for 0 (control), 1, 2 and 4 weeks at low and high acclimation temperatures (15 and 25°C). Both fasting treatment and temperature acclimation had significant effects on all parameters measured (P<0.05). Fasting at the higher temperature had a negative effect on all measured parameters after 1 week (P<0.05). However, when acclimated to the lower temperature, fasting had a negative effect on Ucrit until week 2 and on (ṀO2rest), (ṀO2active) and metabolic scope (MS, (ṀO2active)-(ṀO2rest)) until week 4 (P<0.05). The values of all parameters at the lower temperature were significantly lower than those at the higher temperature in the identical fasting period groups except for (ṀO2rest) of the fish that fasted for 2 weeks. The relationship between fasting time (T) and Ucrit was described as Ucrit(15)=-0.302T(2)-0.800T+35.877 (r=0.781, n=32, P<0.001) and Ucrit(25)=0.471T(2)-3.781T+50.097 (r=0.766, n=32, P<0.001) at 15 and 25°C, respectively. The swimming performance showed less decrease in the early stage of fasting but more decrease in the later stage at the low temperature compared to the high temperature, which might be related to thermal acclimation time, resting metabolism, respiratory capacity, energy stores, enzyme activity in muscle tissue and energy substrate utilization changes with fasting between low and high temperatures. The divergent response of the swimming performance to fasting in qingbo at different temperatures might be an adaptive strategy to seasonal temperature and food resource variation in their habitat. Copyright © 2014. Published by Elsevier Ltd.

Increased benefit of alteplase in patients with ischemic stroke and a high body temperature.

PubMed

de Ridder, Inger; den Hertog, Heleen; van Gemert, Maarten; Dippel, Diederik; van der Worp, Bart

2013-01-01

In observational studies, a high body temperature has been associated with unfavorable outcome. In in vitro studies, the fibrinolytic activity of alteplase decreased 5% per degree Celsius reduction in temperature. The modifying effect of body temperature on treatment with alteplase in patients with acute ischemic stroke is unclear. We assessed the influence of baseline body temperature on the effect of alteplase on functional outcome in patients with acute ischemic stroke, included in the Paracetamol (Acetaminophen) in Stroke (PAIS) trial. PAIS was a randomized, double-blind clinical trial to assess the effect of high-dose paracetamol on functional outcome in patients with acute stroke. For this study, we selected all patients with ischemic stroke and randomization within 6 h of symptom onset. We estimated the effect of treatment with alteplase on the modified Rankin Scale score at 3 months with ordinal logistic regression, stratified by baseline body temperature. We made adjustments for confounding factors and expressed associations as adjusted odds ratios (aOR) with 95% confidence intervals (CI). We also tested for interaction between treatment with alteplase and body temperature. We included 647 of the 1,400 patients in PAIS in our study. Treatment with alteplase was associated with improved functional outcome at 3 months (aOR 1.51, 95% CI 1.09-2.08). In the 286 patients (44%) with a baseline body temperature of 37.0°C or higher, alteplase was associated with a larger effect (aOR 2.13, 95% CI 1.28-3.45) than in patients with a temperature below 37.0°C (aOR 1.11, 95% CI 0.71-1.69). A test for interaction between body temperature and alteplase did not reach statistical significance (p = 0.18). Patients with ischemic stroke and a high body temperature may have a larger benefit of treatment with alteplase than patients with lower body temperatures. These findings are in line with those from in vitro studies, in which lowering temperature decreased the fibrinolytic activity of the enzyme alteplase. This interaction should be explored further in randomized clinical trials of thrombolytic therapy or modification of body temperature. Trials of therapeutic hypothermia should be controlled for treatment with thrombolytics, and trials of thrombolytic treatment should consider body temperature as a potential effect modifier. Copyright © 2013 S. Karger AG, Basel.

Combined effects of temperature acclimation and cadmium exposure on mitochondrial function in eastern oysters Crassostrea virginica gmelin (Bivalvia: Ostreidae).

PubMed

Cherkasov, Anton S; Ringwood, Amy H; Sokolova, Inna M

2006-09-01

Cadmium and temperature have strong impacts on the metabolic physiology of aquatic organisms. To analyze the combined impact of these two stressors on aerobic capacity, effects of Cd exposure (50 microg/L) on mitochondrial function were studied in oysters (Crassostrea virginica) acclimated to 12 and 20 degrees C in winter and to 20 and 28 degrees C in fall. Cadmium exposure had different effects on mitochondrial bioenergetics of oysters depending on the acclimation temperature. In oysters acclimated to 12 degrees C, Cd exposure resulted in elevated intrinsic rates of mitochondrial oxidation, whereas at 28 degrees C, a rapid and pronounced decrease of mitochondrial oxidative capacity was found in Cd-exposed oysters. At the intermediate acclimation temperature (20 degrees C), effects of Cd exposure on intrinsic rates of mitochondrial oxidation were negligible. Degree of coupling significantly decreased in mitochondria from 28 degrees C-acclimated oysters but not in that from 12 degrees C- or 20 degrees C-acclimated oysters. Acclimation at elevated temperatures also increased sensitivity of oyster mitochondria to extramitochondrial Cd. Variation in mitochondrial membrane potential explained 41% of the observed variation in mitochondrial adenosine triphosphate synthesis and proton leak between different acclimation groups of oysters. Temperature-dependent sensitivity of metabolic physiology to Cd has significant implications for toxicity testing and for extrapolation of laboratory studies to field populations of aquatic poikilotherms, indicating the importance of taking into account the thermal regime of the environment.

A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate.

PubMed

Ikäheimo, Tiina M; Jaakkola, Kari; Jokelainen, Jari; Saukkoriipi, Annika; Roivainen, Merja; Juvonen, Raija; Vainio, Olli; Jaakkola, Jouni J K

2016-09-02

Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was -9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m³. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00-1.15)) and maximal (OR 1.08 (1.01-1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03-1.40)) and maximal decrease (OR 1.13 (CI 0.96-1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m³ decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00-1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects.

A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate

PubMed Central

Ikäheimo, Tiina M.; Jaakkola, Kari; Jokelainen, Jari; Saukkoriipi, Annika; Roivainen, Merja; Juvonen, Raija; Vainio, Olli; Jaakkola, Jouni J.K.

2016-01-01

Both temperature and humidity may independently or jointly contribute to the risk of human rhinovirus (HRV) infections, either through altered survival and spread of viruses in the environment or due to changes in host susceptibility. This study examined the relationship between short-term variations in temperature and humidity and the risk of HRV infections in a subarctic climate. We conducted a case-crossover study among conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training and identified 147 HRV cases by real-time PCR. An average temperature, a decline in daily ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods (a week prior and after the onset) were obtained. The average daily temperature preceding HRV infections was −9.9 ± 4.9 °C and the average AH was 2.2 ± 0.9 g/m3. An average (odds ratios (OR) 1.07 (95% confidence interval (CI) 1.00–1.15)) and maximal (OR 1.08 (1.01–1.17)) change in temperature increased the risk of HRV infections by 8% per 1 °C decrease. An average (OR 1.20 (CI 1.03–1.40)) and maximal decrease (OR 1.13 (CI 0.96–1.34)) in AH increased the risk of HRV infection by 13% and 20% per 0.5 g/m3 decrease. A higher average temperature during the three preceding days was positively associated with HRV infections (OR 1.07 (CI 1.00–1.15)). A decrease rather than low temperature and humidity per se during the preceding few days increases the risk of HRV infections in a cold climate. The information is applicable to populations residing in cold climates for appropriate personal protection and prevention of adverse health effects. PMID:27598190

High-Temperature Isothermal Capacitance Transient Spectroscopy Study on Inductively Coupled Plasma Etching Damage for p-GaN Surfaces

NASA Astrophysics Data System (ADS)

Aoki, Toshichika; Wakayama, Hisashi; Kaneda, Naoki; Mishima, Tomoyoshi; Nomoto, Kazuki; Shiojima, Kenji

2013-11-01

The effects of the inductively coupled plasma (ICP) etching damage on the electrical characteristics of low-Mg-doped p-GaN Schottky contacts were evaluated by high-temperature isothermal capacitance transient spectroscopy. A large single peak for an acceptor-type surface state was dominantly detected for as-grown samples. The energy level and state density were obtained to be 1.18 eV above the valence band, which is close to a Ga vacancy (VGa), and 1.5×1013 cm-2, respectively. It was speculated that a small portion of Ga atoms were missing from the surface, and a high VGa density was observed in a few surface layers. The peak intensity decreased by 60% upon annealing at 800 °C, and further decrease was found by ICP etching. This decrease is consistent with the suppression of the memory effect in current-voltage characteristics. Upon annealing and ICP etching, since the VGa structure might be disordered, the peak intensity decreased.

Center-to-limb variation of intensity and polarization in continuum spectra of FGK stars for spherical atmospheres

NASA Astrophysics Data System (ADS)

Kostogryz, N. M.; Milic, I.; Berdyugina, S. V.; Hauschildt, P. H.

2016-02-01

Aims: One of the necessary parameters needed for the interpretation of the light curves of transiting exoplanets or eclipsing binary stars (as well as interferometric measurements of a star or microlensing events) is how the intensity and polarization of light changes from the center to the limb of a star. Scattering and absorption processes in the stellar atmosphere affect both the center-to-limb variation of intensity (CLVI) and polarization (CLVP). In this paper, we present a study of the CLVI and CLVP in continuum spectra, taking into consideration the different contributions of scattering and absorption opacity for a variety of spectral type stars with spherical atmospheres. Methods: We solve the radiative transfer equation for polarized light in the presence of a continuum scattering, taking into consideration the spherical model of a stellar atmosphere. To cross-check our results, we developed two independent codes that are based on Feautrier and short characteristics methods, respectively, Results: We calculate the center-to-limb variation of intensity (CLVI) and polarization (CLVP) in continuum for the Phoenix grid of spherical stellar model atmospheres for a range of effective temperatures (4000-7000 K), gravities (log g = 1.0-5.5), and wavelengths (4000-7000 Å), which are tabulated and available at the CDS. In addition, we present several tests of our codes and compare our calculations for the solar atmosphere with published photometric and polarimetric measurements. We also show that our two codes provide similar results in all considered cases. Conclusions: For sub-giant and dwarf stars (log g = 3.0-4.5), the lower gravity and lower effective temperature of a star lead to higher limb polarization of the star. For giant and supergiant stars (log g = 1.0-2.5), the highest effective temperature yields the largest polarization. By decreasing the effective temperature of a star down to 4500-5500 K (depending on log g), the limb polarization decreases and reaches a local minimum. It increases again with a corresponding decrease in temperature down to 4000 K. For the most compact dwarf stars (log g = 5.0-5.5), the limb polarization degree shows a maximum for models with effective temperatures in the range 4200-4600 K (depending on log g) and decreases toward higher and lower temperatures. The intensity and polarization profiles are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A87

Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of Soybean (Glycine max) at elevated [CO2] and temperatures under fully open air field conditions

USDA-ARS?s Scientific Manuscript database

The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on 1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the ma...

The heat is on: room temperature affects laboratory equipment--an observational study.

PubMed

Butler, Julia M; Johnson, Jane E; Boone, William R

2013-10-01

To evaluate the effect of ambient room temperature on equipment typically used in in vitro fertilization (IVF). We set the control temperature of the room to 20 °C (+/-0.3) and used CIMScan probes to record temperatures of the following equipment: six microscope heating stages, four incubators, five slide warmers and three heating blocks. We then increased the room temperature to 26 °C (+/-0.3) or decreased it to 17 °C (+/-0.3) and monitored the same equipment again. We wanted to determine what role, if any, changing room temperature has on equipment temperature fluctuation. There was a direct relationship between room temperature and equipment temperature stability. When room temperature increased or decreased, equipment temperature reacted in a corresponding manner. Statistical differences between equipment were found when the room temperature changed. What is also noteworthy is that temperature of equipment responded within 5 min to a change in room temperature. Clearly, it is necessary to be aware of the affect of room temperature on equipment when performing assisted reproductive procedures. Room and equipment temperatures should be monitored faithfully and adjusted as frequently as needed, so that consistent culture conditions can be maintained. If more stringent temperature control can be achieved, human assisted reproduction success rates may improve.

Effects of Genotype and Growth Temperature on the Contents of Tannin, Phytate and In Vitro Iron Availability of Sorghum Grains

PubMed Central

Wu, Gangcheng; Johnson, Stuart K.; Bornman, Janet F.; Bennett, Sarita J.; Singh, Vijaya; Simic, Azra; Fang, Zhongxiang

2016-01-01

Background It has been predicted that the global temperature will rise in the future, which means crops including sorghum will likely be grown under higher temperatures, and consequently may affect the nutritional properties. Methods The effects of two growth temperatures (OT, day/night 32/21°C; HT 38/21°C) on tannin, phytate, mineral, and in vitro iron availability of raw and cooked grains (as porridge) of six sorghum genotypes were investigated. Results Tannin content significantly decreased across all sorghum genotypes under high growth temperature (P ≤0.05), while the phytate and mineral contents maintained the same level, increased or decreased significantly, depending on the genotype. The in vitro iron availability in most sorghum genotypes was also significantly reduced under high temperature, except for Ai4, which showed a pronounced increase (P ≤0.05). The cooking process significantly reduced tannin content in all sorghum genotypes (P ≤0.05), while the phytate content and in vitro iron availability were not significantly affected. Conclusions This research provides some new information on sorghum grain nutritional properties when grown under predicted future higher temperatures, which could be important for humans where sorghum grains are consumed as staple food. PMID:26859483

Fuels Performance | Transportation Research | NREL

Science.gov Websites

Chemistry. (2014) Saturated Monoglyceride Effects on Low-Temperature Performance of Biodiesel Blends. G.M more energy-efficient vehicles on the road to displace oil consumption, decrease greenhouse gas . (2013) Ignition Quality Tester (IQT) Investigation of the Negative Temperature Coefficient Region of

Effect of alternating day and night temperature on short day-induced bud set and subsequent bud burst in long days in Norway spruce

PubMed Central

Olsen, Jorunn E.; Lee, YeonKyeong; Junttila, Olavi

2014-01-01

Young seedlings of the conifer Norway spruce exhibit short day (SD)-induced cessation of apical growth and bud set. Although different, constant temperatures under SD are known to modulate timing of bud set and depth of dormancy with development of deeper dormancy under higher compared to lower temperature, systematic studies of effects of alternating day (DT) and night temperatures (NT) are limited. To shed light on this, seedlings of different provenances of Norway spruce were exposed to a wide range of DT-NT combinations during bud development, followed by transfer to forcing conditions of long days (LD) and 18°C, directly or after different periods of chilling. Although no specific effect of alternating DT/NT was found, the results demonstrate that the effects of DT under SD on bud set and subsequent bud break are significantly modified by NT in a complex way. The effects on bud break persisted after chilling. Since time to bud set correlated with the daily mean temperature under SD at DTs of 18 and 21°C, but not a DT of 15°C, time to bud set apparently also depend on the specific DT, implying that the effect of NT depends on the actual DT. Although higher temperature under SD generally results in later bud break after transfer to forcing conditions, the fastest bud flush was observed at intermediate NTs. This might be due to a bud break-hastening chilling effect of intermediate compared to higher temperatures, and delayed bud development to a stage where bud burst can occur, under lower temperatures. Also, time to bud burst in un-chilled seedlings decreased with increasing SD-duration, suggesting that bud development must reach a certain stage before the processes leading to bud burst are initiated. The present results also indicate that low temperature during bud development had a larger effect on the most southern compared to the most northern provenance studied. Decreasing time to bud burst was observed with increasing northern latitude of origin in un-chilled as well as chilled plants. In conclusion, being a highly temperature-dependent process, bud development is strongly delayed by low temperature, and the effects of DT is significantly modified by NT in a complex manner. PMID:25538722

Permeability of acetic acid across gel and liquid-crystalline lipid bilayers conforms to free-surface-area theory.

PubMed Central

Xiang, T X; Anderson, B D

1997-01-01

Solubility-diffusion theory, which treats the lipid bilayer membrane as a bulk lipid solvent into which permeants must partition and diffuse across, fails to account for the effects of lipid bilayer chain order on the permeability coefficient of any given permeant. This study addresses the scaling factor that must be applied to predictions from solubility-diffusion theory to correct for chain ordering. The effects of bilayer chemical composition, temperature, and phase structure on the permeability coefficient (Pm) of acetic acid were investigated in large unilamellar vesicles by a combined method of NMR line broadening and dynamic light scattering. Permeability values were obtained in distearoylphosphatidylcholine, dipalmitoylphosphatidylcholine, dimyristoylphosphatidylcholine, and dilauroylphosphatidylcholine bilayers, and their mixtures with cholesterol, at various temperatures both above and below the gel-->liquid-crystalline phase transition temperatures (Tm). A new scaling factor, the permeability decrement f, is introduced to account for the decrease in permeability coefficient from that predicted by solubility-diffusion theory owing to chain ordering in lipid bilayers. Values of f were obtained by division of the observed Pm by the permeability coefficient predicted from a bulk solubility-diffusion model. In liquid-crystalline phases, a strong correlation (r = 0.94) between f and the normalized surface density sigma was obtained: in f = 5.3 - 10.6 sigma. Activation energies (Ea) for the permeability of acetic acid decreased with decreasing phospholipid chain length and correlated with the sensitivity of chain ordering to temperature, [symbol: see text] sigma/[symbol: see text](1/T), as chain length was varied. Pm values decreased abruptly at temperatures below the main phase transition temperatures in pure dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine bilayers (30-60-fold) and below the pretransition in dipalmitoylphosphatidylcholine bilayers (8-fold), and the linear relationship between in f and sigma established for liquid-crystalline bilayers was no longer followed. However, in both gel and liquid-crystalline phases in f was found to exhibit an inverse correlation with free surface area (in f = -0.31 - 29.1/af, where af is the average free area (in square angstroms) per lipid molecule). Thus, the lipid bilayer permeability of acetic acid can be predicted from the relevant chain-packing properties in the bilayer (free surface area), regardless of whether chain ordering is varied by changes in temperature, lipid chain length, cholesterol concentration, or bilayer phase structure, provided that temperature effects on permeant dehydration and diffusion and the chain-length effects on bilayer barrier thickness are properly taken into account. PMID:8994607

Evaluating linear response in active systems with no perturbing field: Application to the calculation of an effective temperature

NASA Astrophysics Data System (ADS)

Szamel, Grzegorz

We present a method for the evaluation of time-dependent linear response functions for systems of active particles propelled by a persistent (colored) noise from unperturbed simulations. The method is inspired by the Malliavin weights sampling method proposed earlier for systems of (passive) Brownian particles. We illustrate our method by evaluating a linear response function for a single active particle in an external harmonic potential. As an application, we calculate the time-dependent mobility function and an effective temperature, defined through the Einstein relation between the self-diffusion and mobility coefficients, for a system of active particles interacting via a screened-Coulomb potential. We find that this effective temperature decreases with increasing persistence time of the self-propulsion. Initially, for not too large persistence times, it changes rather slowly, but then it decreases markedly when the persistence length of the self-propelled motion becomes comparable with the particle size. Supported by NSF and ERC.