High Temperatures (high + temperature)

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of High Temperatures

  • very high temperature

  • Terms modified by High Temperatures

  • high temperature annealing
  • high temperature application
  • high temperature condition
  • high temperature treatment

  • Selected Abstracts


    Thermal Stability of W- xRe/TiC/SiC Systems,=,0, 5 and 25 at % Re) at High Temperature,

    ADVANCED ENGINEERING MATERIALS, Issue 5 2009
    Jerome Roger
    To ensure the integrity and sustainability of high-temperature applications, the development of protective materials is actually one of the major challenge in materials science. In our study, we examined the effect of a TiC film interlayered between W- xRe (x,=,0, 5 or 25 at % Re) and SiC. The protection given by TiC layer was considered in the 1573,1873,K temperature range and for TiC thicknesses up to about 100,,m. [source]


    X-linked QTL for knockdown resistance to high temperature in Drosophila melanogaster

    INSECT MOLECULAR BIOLOGY, Issue 4 2007
    F. M. Norry
    Abstract Knockdown Resistance to High Temperature (KRHT) is an adaptive trait of thermotolerance in insects. An interval mapping was performed on chromosome X of Drosophila melanogaster to search for quantitative trait loci (QTL) affecting KRHT. A backcross population was obtained from two lines that dramatically differ for KRHT. Microsatellites were used as markers. Composite interval mapping identified a large-effect QTL in the region of band 10 where putative candidate genes map. To further test for this QTL a set of recombinant (but non-inbred) lines was obtained from backcrosses between the parental lines used for the interval mapping. Recombinant line analysis confirmed that one QTL is targeted by band 10. We identify and discuss candidate loci contained within our QTL region. [source]


    Retaining Catalyst Performance at High Temperature: The Use of a Tetraphosphine Ligand in the Highly Regioselective Hydroformylation of Terminal Olefins

    ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2007
    Yongjun Yan
    Abstract A new tetraphosphine ligand has been developed and applied in the highly regioselective hydroformylation of terminal olefins. The ligand retains high performance at high temperature when compared with its bisphosphine analogue. [source]


    Experimental Investigation of Eclogite Rheology and Its Fabrics at High Temperature and Pressure

    JOURNAL OF METAMORPHIC GEOLOGY, Issue 2 2007
    J. ZHANG
    Abstract Eclogite plays an important role in mantle convection and geodynamics in subduction zones. An improved understanding of processes in the deeper levels of subduction zones and collision belts requires information on eclogite rheology. However, the deformation processes and associated fabrics in eclogite are not well understood. Incompatible views of deformation mechanism have been proposed for both garnet and omphacite. We present here deformation behaviour of eclogite at temperatures of 1027,1427 C, confining pressures of 2.5,3.5 GPa, and strain rates of 1 10,5 s,1 to 5 10,4 s,1. We obtained a power-law creep for the high temperature and pressure deformation of a ,dry' eclogite (50 vol.% garnet, 40% omphacite and 10% quartz) with A = 103.3 1.0, n = 3.5 0.4, ,E =403 30 KJ mol,1 and ,V = 27.2 cm3 mol,1. The two principal minerals of eclogite have greatly different strengths. Progressive increase of garnet results in a smooth increase in strength. Analysis by electron back-scattered diffraction shows that: (1) garnet displays pole figures with near random distributions of misorientation angle under both dry and wet conditions; (2) omphacite shows pronounced lattice preferred orientations (LPOs), suggesting a dominant dislocation creep mechanism. Further investigation into the water effects on eclogite show: (3) water content does not influence the style of omphacite fabric but increases slightly the fabric strength; (4) grain boundary processes dominate the deformation of garnet under high water fugacity or high shear-strain conditions, yielding a random LPO similar to that of non-deforming garnet, despite the strong shape preferred orientation (SPO) observed. {110} [001] slip may dominate the deformation of rutile. Quartz displays complicated and inconsistent LPOs in eclogite. These results are remarkably similar to observations from deformed eclogites in nature. [source]


    ,-Gallium Oxide as Oxygen Gas Sensors at a High Temperature

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007
    Marilena Bartic
    Resistive oxygen sensors based on gallium oxide were fabricated in order to analyze their sensing performances (as sensitivity, response, and recovery time) in an oxygen atmosphere at 1000C. We prepared three types of sensors using a ,-Ga2O3 single crystal in a sandwich structure with Pt pad electrodes and ,-Ga2O3 polycrystalline thin films deposited by using both the sputtering technique and the chemical solution deposition method. For thin-film sensors, Pt interdigital electrodes were deposited on the surface of the films using the lift-off method. X-ray diffraction and atomic force microscopy investigations were performed to compare the structure and surface morphology of the samples. We achieved a response time of 10 s at 1000C, while the sensitivity was 1.03 for the single crystal and 1.35,1.45 for thin films. The sensing properties depend on the preparation condition of Ga2O3 devices. [source]


    Phase Transition and Failure at High Temperature of Bismuth-Layered Piezoelectric Ceramics

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006
    Liaoying Zheng
    High-temperature bismuth-layered piezoelectric ceramics (CaxSr1,x)Bi4Ti4O15 have been prepared by the conventional solid reaction method. Our results reveal that there is a "phase transition induced by the composition" taking place in the solid solution at around x=0.4. During transition, the crystal structure changes from orthorhombic to pseudo-tetragonal and then back to orthorhombic. Although all (CaxSr1,x)Bi4Ti4O15 (with any x value) undergo a second-order ferroelectric-to-ferroelectric phase transition at about 200C below their Curie temperature, only the ceramic with x=0.4 exhibits a failure in piezoelectric properties during the transition. It is suggested that, on the basis of the X-ray photoelectron spectroscopy results, this material failure is induced by the high concentration of oxygen vacancies in the material during the phase transition. [source]


    Instability of Statical Solutions of Steel 2D Frames in High Temperature

    PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008
    Jerzy Pil, niakArticle first published online: 25 FEB 200
    This work is intended as an attempt to stability analysis of static equations of flat steel frames in fire. High temperature during fire adversely affects on structural steel elements by activating irreversible processes (plasticity, creep). Rheological property can be described in simplified form by power term. Steel properties is represented by physical equations which contains three terms: linear (elasticity), nonlinear and rheological (related to creep). ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Stabilization of Taq DNA Polymerase at High Temperature by Protein Folding Pathways From a Hyperthermophilic Archaeon, Pyrococcus furiosus

    BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006
    Pongpan Laksanalamai
    Abstract Pyrococcus furiosus, a hyperthermophilic archaeon growing optimally at 100C, encodes three protein chaperones, a small heat shock protein (sHsp), a prefoldin (Pfd), and a chaperonin (Cpn). In this study, we report that the passive chaperones sHsp and Pfd from P. furiosus can boost the protein refolding activity of the ATP-dependent Cpn from the same hyperthermophile. The thermo-stability of Taq polymerase was significantly improved by combinations of P. furiosus chaperones, showing ongoing protein folding activity at elevated temperatures and during thermal cycling. Based on these results, we propose that the protein folding apparatus in the hyperthermophilic archaeon, P. furiosus can be utilized to enhance the durability and cost effectiveness of high temperature biocatalysts. 2005 Wiley Periodicals, Inc. [source]


    Cyclization at Very High Temperature.

    CHEMINFORM, Issue 34 2005
    N-Dialkyl Cinnamic Amides into Pyrrolidin-2-ones under FVT Conditions., Thermal Transformations of N-Alkyl
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]


    Preparation and Transport Properties of New Oxide Ion Conductors KNb1-xMgxO3-, by High Temperature and Pressure.

    CHEMINFORM, Issue 20 2003
    Liping Li
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]


    Nanosized Glass Frit as an Adhesion Promoter for Ink-Jet Printed Conductive Patterns on Glass Substrates Annealed at High Temperatures,

    ADVANCED FUNCTIONAL MATERIALS, Issue 19 2008
    Daehwan Jang
    Abstract Ink-jet printed metal nanoparticle films have been shown to anneal at high temperatures (above 500,C) to highly conductive metal films on glass or ceramic substrates, but they suffer from cracking and inadequate substrate adhesion. Here, we report printable conductive materials, with added nanosized glass frit that can be annealed at 500,C to form a crack-free dense microstructure that adheres well to glass substrates. This overcomes the previous challenges while still retaining the desired high film conductivity. Controlling the particle characteristics and dispersion behavior plays an important role in successfully incorporating the glass frit into the conductive inks. [source]


    Heating of ,-Lactoglobulin A Solution in a Closed System at High Temperatures

    JOURNAL OF FOOD SCIENCE, Issue 5 2001
    S. Photchanachai
    ABSTRACT ,-Lactoglobulin A solution at pH 6.4 was heated to 180 C at the rate of 6 C/min. By differential scanning calorimetry two independent endothermic peaks were observed. The first peak appeared below 100 C is corresponded to the thermal denaturation of protein. This conformational change led to the aggregation and polymerization of molecules through disulfide linkage, particularly observed above 100 C. The second endothermic peak appeared around 150 C, which was brought by the decomposition of molecules as judged from electrophoresis. Up to 100 C the viscosity of ,-lactoglobulin A solution increased by heating, while the viscosity was reduced beyond 113 C, due to change in the size of aggregate and decomposition of ,-lactoglobulin A molecules. [source]


    Oxygen Transport in Silica at High Temperatures: Implications of Oxidation Kinetics

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2001
    C. Eric Ramberg
    The apparent change in activation energy describing the parabolic rate constant for the passive oxidation of SiC is examined. New data are combined with reevaluated previous results to determine the influences of crystallinity, impurity contamination, and multiple flux mechanisms. The results suggest that the high-temperature transition from interstitial-dominant to network-dominant oxygen transport is a property of amorphous SiO2 scales and does not exist for cristobalite. Highly crystalline scales do not show this transition. Agreement among various studies also suggests that, for high-purity SiO2 scales, there is no difference between the rates of interstitial oxygen transport in amorphous SiO2 and in ,-cristobalite. [source]


    Solubility of Magnesia in Polycrystalline Alumina at High Temperatures

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2001
    C. Greskovich
    High-purity Al2O3 compacts were doped with 0,350 ppm (by weight) of MgO using a liquid immersion technique and equilibrated at temperatures between 1700 and 2000C under hydrogen. The solubility limits of MgO in Al2O3 at temperatures of 1720 and 1880C were very low, ,75 and 175 ppm, respectively. Variation of MgO solubility with temperature could be represented by the equation, ln Mg/Al = 3.80,2.63 104/T. The small MgO solubilities were understood by the high enthalpy (326 kJ/mol) of solution. The results of this study suggested that previous investigations on sintering and grain-growth mechanisms in MgO-doped Al2O3 were probably not done in single-phase Al2O3 solid solutions. However, the conclusions on sintering and grain-growth mechanisms in prior research work in MgO-doped A2O3 may be correct. The effects of SiO2 impurity and grain size on MgO solubility are discussed. Previous grain-growth experiments in MgO-doped Al2O3 are described that demonstrate the clearest evidence for grain-boundary mobility controlled by a solid-solution mechanism. [source]


    Kinetic Evidence for the Influence of Subsurface Oxygen on Palladium Surfaces Towards CO Oxidation at High Temperatures

    CHEMISTRY - AN ASIAN JOURNAL, Issue 1 2009
    Chinnakonda
    Abstract Transient state kinetics of the catalytic oxidation of CO with O2 on Pd-surfaces has been measured under isothermal conditions by using a molecular beam approach. Systematic studies were carried out as a function of reaction temperature and CO+O2 composition. With sufficient kinetic evidence, we have demonstrated the positive influence of subsurface oxygen towards CO-adsorption and oxidation to CO2 at high temperatures (600,900,K) on Pd-surfaces, and the likely electronic nature of the surface changes with oxygen in the subsurface. These studies also provide a direct proof for CO-adsorption with a significantly reactive sticking coefficient at high temperatures on Pd-surfaces exhibiting a significant subsurface O-coverage. [source]


    Bimodal life cycle of the burying beetle Nicrophorus quadripunctatus in relation to its summer reproductive diapause

    ECOLOGICAL ENTOMOLOGY, Issue 2 2002
    Tomoyosi Nisimura
    Abstract 1. Under natural conditions in Kyoto, Japan, the reproductive activities of Nicrophorus quadripunctatus Kraatz (Coleoptera: Silphidae) decreased in summer and the species showed a bimodal life cycle. 2. In the laboratory, most adult pairs raised at 20 C under a LD 12:12 h regime reproduced when provided with a piece of chicken. In adults raised at 20 C under a LD 16:8 h regime, however, both reproductive behaviour and ovarian development were reduced. It is concluded that these adults entered a reproductive summer diapause. 3. High temperature (25 C) also suppressed the reproductive behaviour even under a favourable LD 12:12 h regime. In the field, therefore, adults reduce their reproductive activity in summer because of diapause induced by long-day photoperiods and direct inhibition of reproduction by high temperatures. 4. When the temperature was changed from 20 C to 25 C immediately after hatching of larvae, they reached the wandering stage in 95% of adult pairs. When the temperature was changed from 20 C to 25 C immediately after oviposition, however, no larvae hatched in 85% of pairs. Egg mortality was significantly higher at 25 C than at 20 and 22.5 C; no eggs hatched at 27.5 C. The physiological mechanisms for reducing reproduction probably prevent the beetles from inefficient oviposition in summer. [source]


    Climatic effects on the breeding phenology and reproductive success of an arctic-nesting goose species

    GLOBAL CHANGE BIOLOGY, Issue 9 2008
    MARIE-HLNE DICKEY
    Abstract Climate warming is pronounced in the Arctic and migratory birds are expected to be among the most affected species. We examined the effects of local and regional climatic variations on the breeding phenology and reproductive success of greater snow geese (Chen caerulescens atlantica), a migratory species nesting in the Canadian Arctic. We used a long-term dataset based on the monitoring of 5447 nests and the measurements of 19 234 goslings over 16 years (1989,2004) on Bylot Island. About 50% of variation in the reproductive phenology of individuals was explained by spring climatic factors. High mean temperatures and, to a lesser extent, low snow cover in spring were associated with an increase in nest density and early egg-laying and hatching dates. High temperature in spring and high early summer rainfall were positively related to nesting success. These effects may result from a reduction in egg predation rate when the density of nesting geese is high and when increased water availability allows females to stay close to their nest during incubation recesses. Summer brood loss and production of young at the end of the summer increased when values of the summer Arctic Oscillation (AO) index were either very positive (low temperatures) or very negative (high temperatures), indicating that these components of the breeding success were most influenced by the regional summer climate. Gosling mass and size near fledging were reduced in years with high spring temperatures. This effect is likely due to a reduced availability of high quality food in years with early spring, either due to food depletion resulting from high brood density or a mismatch between hatching date of goslings and the timing of the peak of plant quality. Our analysis suggests that climate warming should advance the reproductive phenology of geese, but that high spring temperatures and extreme values of the summer AO index may decrease their reproductive success up to fledging. [source]


    Haematological toxicity of drugs used in psychiatry,

    HUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue S1 2008
    Robert J. Flanagan
    Abstract Almost all classes of psychotropic agents have been reported to cause blood dyscrasias. Mechanisms include direct toxic effects upon the bone marrow, the formation of antibodies against haematopoietic precursors or involve peripheral destruction of cells. Agranulocytosis is probably the most important drug-related blood dyscrasia. The mortality from drug-induced agranulocytosis is 5,10% in Western countries. The manifestations of agranulocytosis are secondary to infection. Aggressive treatment with intravenous broad-spectrum antimicrobials and bone marrow stimulants may be required. Of drugs encountered in psychiatry, antipsychotics including clozapine (risk of agranulocytosis approximately 0.8%, predominantly in the first year of treatment) and phenothiazines (chlorpromazine agranulocytosis risk approximately 0.13%), and antiepileptics (notably carbamazepine, neutropenia risk approximately 0.5%) are the most common causes of drug-related neutropenia/agranulocytosis. Drugs known to cause neutropenia should not be used concomitantly with other drugs known to cause this problem. High temperature and other indicators of possible infection should be looked for routinely during treatment. Clozapine is well known as a drug that can cause blood dyscrasias, but olanzapine and other atypicals may also cause similar problems. In addition to genetic factors, there are likely to be dose-related and immunological components to these phenomena. Important lessons have been learnt from the haematological monitoring that is necessary with clozapine and the monitoring has been very successful in preventing deaths related to clozapine-induced agranulocytosis. Continuing research into the mechanisms of drug-induced neutropenia and agranulocytosis may serve to further enhance the safe use not only of clozapine, but also of other agents. Copyright 2007 John Wiley & Sons, Ltd. [source]


    Synthesis of Large-Area Graphene Layers on Poly-Nickel Substrate by Chemical Vapor Deposition: Wrinkle Formation

    ADVANCED MATERIALS, Issue 22 2009
    Seung Jin Chae
    Large-area, few-layer graphene is grown on a poly-nickel substrate using optimized CVD conditions. High temperature, short growth time, and an optimal gas mixing ratio (C2H2/H2,=,2/45) are found to be necessary to synthesize highly crystalline few-layer grapheme, which may find applications in electronic devices. The wrinkles that are observed under all growth conditions are proposed to be formed by two processes. [source]


    Response of Oryzacystatin I Transformed Tobacco Plants to Drought, Heat and Light Stress

    JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2010
    K. Demirevska
    Abstract Transformed tobacco plants expressing a rice cysteine proteinase inhibitor (OC-I) and non-transformed plants were grown in a controlled environment and subjected to various stresses. Two-month-old transformed and non-transformed plants were exposed for 5 days to drought conditions by withholding watering. High temperature (40 C) was applied additionally at day 6th for 5 h either individually or in combination with drought. All stress treatments were applied under low (150 ,mol m,2 s,1 PPFD) and high light intensity (HL) of 1000 ,mol m,2 s,1 PPFD to determine if OC-I expression might provide protection under combination of stresses usually existing in nature. Drought stress led to diminution in leaf relative water content, photosynthesis inhibition, decrease in chlorophyll content and accumulation of malondialdehyde and proline. Heat stress alone did not affect the plants significantly, but intensified the effect of drought stress. HL intensity further increased the proline content. OC-I transformed plants grown under low light intensity had significantly higher total superoxide dismutase and guaiacol peroxidase activities as well as their isoforms than non-transformed control plants under non-stress and stress conditions. Catalase activity was not highly affected by OC-I expression. Results indicate that OC-I expression in tobacco plants provides protection of the antioxidative enzymes superoxide dismutase and guaiacol peroxidise under both non-stress and stress conditions. [source]


    Climate change may account for the decline in British ring ouzels Turdus torquatus

    JOURNAL OF ANIMAL ECOLOGY, Issue 3 2006
    COLIN M. BEALE
    Summary 1Climate change is already affecting biodiversity, but the number of species for which reliable models relate weather and climate to demographic parameters is low. 2We modelled the effect of temperature and rainfall on the breeding success and territory occupancy of ring ouzels Turdus torquatus (L.) in northern Britain, using data from a range of study areas, including one where there was a long-term decline in ring ouzel abundance. 3Timing of breeding was significantly related to meteorological variables affecting birds in the early spring, though there was no evidence that laying dates had advanced. Breeding success was not significantly related to weather variables; instead, over 90% of annual variation in this parameter could be explained by density dependence. 4Annual change in territory occupancy was linked to rainfall and temperature the preceding summer, after the main breeding season and to rainfall in the wintering grounds 24 months previously, coincident with the period of juniper Juniperus sp. (L.) flowering. High temperature in late summer, intermediate levels of late summer rainfall, and high spring rainfall in Morocco 24 months previously all had negative impacts on territory occupancy the following year. 5All three weather variables have changed over recent decades, with a significant increase in summer temperature, a significant decrease in summer rainfall, and a nonsignificant decline in Moroccan spring rainfall. A model based on these trends alone predicted an annual decline in occupancy of 36% (compared with an observed decline of 12%), and suggested that increased summer temperatures may underlie declines in the British ring ouzel population. 6Changes in summer temperature after the main breeding period could affect the survival rates of adult and/or juvenile birds. An improved understanding of the post-breeding ecology of ring ouzels is required to elucidate the mechanisms and causes of this relationship. Such knowledge might allow management aimed at buffering the impacts of climate change on ring ouzels. [source]


    The effects of thermal effluent exposure on the gametogenesis of female fish

    JOURNAL OF FISH BIOLOGY, Issue 1 2000
    D. Luk
    High temperature in Swedish and Lithuanian thermal effluent areas influenced gametogenesis of female perch Perca fluviatilis, roach Rutilus rutilus and pike Esox lucius negatively, indicating reduced reproductive capacity. Oocyte atresia started during vitellogenesis in autumn, and was often followed by asynchronous egg cell development. Among other anomalies, multi-nucleus oocytes and hermaphroditism were observed. No significant impact was seen in silver bream Blicca bjoerkna. Ruffe Gymnocephalus cernuus reacted by a tendency to produce an additional mature oocyte generation during the spawning period. Ovaries in roach from coastal areas were often infected by a microsporidian parasite Pleistophora mirandellae, causing severe damage to the gonad. Parasites were also detected in pike, but neither in perch nor in lake populations of roach. Fish living in open coastal environments did not avoid impact by moving out of the heated areas. There seems to be a conflict in some temperate fish between temperature preference behaviour and safeguarding normal reproduction. [source]


    Large Enhancement in Conductivity of Polyaniline Films by Cold Stretching

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 10 2010
    Hong-Mei Xiao
    Abstract The hot-stretching method has been well accepted for enhancing the electrical conductivity of conducting polymer films. High temperature is the prerequisite to soften the polymer to highly align and elongate the polymeric molecular chains. In this study, the cold-stretching method is proposed for the first time to enhance the conductivity of conducting polymeric films. Polyaniline (PANI) films are stretched at room temperature to different strain levels. It is observed that the applied strain has significant effects on the morphology, molecular chain structure, crystallinity, and crosslinking of the PANI films. As a result, the conductivity of PANI films is effectively increased by the cold-stretching process. Particularly, a maximum conductivity with an 18.4-fold increase in the direction parallel to the stretched direction is obtained when the elastic limit strain is applied. Compared to hot stretching, cold stretching is unique due to the extremely low dimensional change and very high efficiency achieved. [source]


    Bipolaris sorokiniana, a cereal pathogen of global concern: cytological and molecular approaches towards better control,

    MOLECULAR PLANT PATHOLOGY, Issue 4 2002
    Jagdish Kumar
    Summary Bipolaris sorokiniana (teleomorph Cochliobolus sativus ) is the causal agent of common root rot, leaf spot disease, seedling blight, head blight, and black point of wheat and barley. The fungus is one of the most serious foliar disease constraints for both crops in warmer growing areas and causes significant yield losses. High temperature and high relative humidity favour the outbreak of the disease, in particular in South Asia's intensive ,irrigated wheat,rice' production systems. In this article, we review the taxonomy and worldwide distribution, as well as strategies to counteract the disease as an emerging threat to cereal production systems. We also review the current understanding of the cytological and molecular aspects of the interaction of the fungus with its cereal hosts, which makes B. sorokiniana a model organism for studying plant defence responses to hemibiotrophic pathogens. The contrasting roles of cell death and H 2O2 generation in plant defence during biotrophic and necrotrophic fungal growth phases are discussed. [source]


    High temperature causes masculinization of genetically female medaka by elevation of cortisol

    MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2010
    Yuki Hayashi
    In poikilothermic vertebrates, sex determination is sometimes influenced by environmental factors such as temperature. However, little is known about the molecular mechanisms underlying environmental sex determination. The medaka (Oryzias latipes) is a teleost fish with an XX/XY sex determination system. Recently, it was reported that XX medaka can be sex-reversed into phenotypic males by high water temperature (HT; 32,34C) treatment during the sex differentiation period. Here we report that cortisol caused female-to-male sex reversal and that metyrapone (an inhibitor of cortisol synthesis) inhibited HT-induced masculinization of XX medaka. HT treatment caused elevation of whole-body levels of cortisol, while metyrapone suppressed the elevation by HT treatment during sexual differentiation. Moreover, cortisol and 33C treatments inhibited female-type proliferation of germ cells as well as expression of follicle-stimulating hormone receptor (fshr) mRNA in XX medaka during sexual differentiation. These results strongly suggest that HT induces masculinization of XX medaka by elevation of cortisol level, which, in turn, causes suppression of germ cell proliferation and of fshr mRNA expression. Mol. Reprod. Dev. 77: 679,686, 2010. 2010 Wiley-Liss, Inc. [source]


    High temperature causes arrest of cell cycle in G2 phase in BmN cells derived from the silkworm, Bombyx mori

    PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2007
    TAKASHI KIUCHI
    Abstract The influence of temperature on the insect cell line, BmN, derived from the silkworm, Bombyx mori is investigated. These cells proliferate at an accelerated pace as the temperature increases from 22 to 30 C, but the growth rate slows at 34 C, and proliferation stops at 38 C. At high temperatures, abnormal cellular morphology is observed. Cells treated at 38 C have cytoplasmic bilateral protrusions and they gradually aggregate and float in the medium. BmN cells without proliferation at 38 C are viable but have reduced DNA synthesis. At high temperatures, the cell cycle of BmN cells halts at the G2 phase. After heat treatment of the larvae, an accumulation of larval haemocytes with high DNA content is found, which suggests that the cell cycle arrest at G2 also occurs in the silkworm at high temperatures. [source]


    Genotypic and temperature effects on wheat grain yield and quality in a hot irrigated environment

    PLANT BREEDING, Issue 4 2006
    I. S. A. Tahir
    Abstract High temperature influences both grain yield and end-use quality of wheat. The objectives of this study were to evaluate the performance of selected wheat genotypes under heat stress and to examine the effects of high temperatures during grain filling on grain yield and end-use quality parameters. Fifteen bread wheat genotypes in 2000/2001 and 18 genotypes in 2002/2003 were evaluated under the optimum and late-sowing conditions of the irrigated hot environment of the Gezira Research Farm, Wad Medani, Sudan. The genotypes comprised released varieties and elite lines from the Sudanese wheat improvement programme. Data collected included grain yield, grain weight and grain end-use quality including protein content, protein composition, SDS sedimentation values (SDSS) and gluten strength as determined by mixograph analyses. High temperatures significantly decreased grain yield by decreasing grain weight. Although genotypes exhibited variation in magnitude of response, results indicated that high temperature during grain filling increased both soluble and insoluble protein contents, SDSS, mixograph peak height (MPH) and the descending slope at 2 min past peak (MDS). In contrast, mixograph peak time (MPT) and the curve width at 2 min past peak (MCW) were significantly decreased. Flour protein correlated positively with SDSS, MPH and MDS and negatively with MCW. MPT correlated negatively with MDS and positively with MCW. Results indicate that high temperature increased both soluble and insoluble protein contents, SDSS and MPH, and hence the gluten strength, but decreased flour mixing time and tolerance and hence the dough elasticity. Variation observed among genotypes suggests that grain end-use quality could be improved under high temperature conditions utilizing the available variability; however, it might require evaluation under various growing conditions. [source]


    Instability of Statical Solutions of Steel 2D Frames in High Temperature

    PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008
    Jerzy Pil, niakArticle first published online: 25 FEB 200
    This work is intended as an attempt to stability analysis of static equations of flat steel frames in fire. High temperature during fire adversely affects on structural steel elements by activating irreversible processes (plasticity, creep). Rheological property can be described in simplified form by power term. Steel properties is represented by physical equations which contains three terms: linear (elasticity), nonlinear and rheological (related to creep). ( 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    High temperature does not alter fatigability in intact mouse skeletal muscle fibres

    THE JOURNAL OF PHYSIOLOGY, Issue 19 2009
    Nicolas Place
    Intense activation of skeletal muscle results in fatigue development, which involves impaired function of the muscle cells resulting in weaker and slower contractions. Intense muscle activity also results in increased heat production and muscle temperature may rise by up to ,6C. Hyperthermia is associated with impaired exercise performance in vivo and recent studies have shown contractile dysfunction and premature fatigue development in easily fatigued muscle fibres stimulated at high temperatures and these defects were attributed to oxidative stress. Here we studied whether fatigue-resistant soleus fibres stimulated at increased temperature show premature fatigue development and whether increasing the level of oxidative stress accelerates fatigue development. Intact single fibres or small bundles of soleus fibres were fatigued by 600 ms tetani given at 2 s intervals at 37C and 43C, which is the highest temperature the muscle would experience in vivo. Tetanic force in the unfatigued state was not significantly different at the two temperatures. With 100 fatiguing tetani, force decreased by ,15% at both temperatures; the free cytosolic [Ca2+] (assessed with indo-1) showed a similar ,10% decrease at both temperatures. The oxidative stress during fatigue at 43C was increased by application of 10 ,m hydrogen peroxide or tert-butyl hydroperoxide and this did not cause premature fatigue development. In summary, fatigue-resistant muscle fibres do not display impaired contractility and fatigue resistance at the highest temperature that mammals, including humans, would experience in vivo. Thus, intrinsic defects in fatigue-resistant muscle fibres cannot explain the decreased physical performance at high temperatures. [source]


    The synergetic effect of plasma and catalyst on simultaneous removal of SO2 and NOx

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010
    Jun Han
    Abstract For the requirements of nitric oxide(NOx) and sulfur dioxide(SO2) removal in coal-fired power plant, a new nonthermal plasma system combined with catalyst was developed. Moreover, the effect of parameters such as temperature, atmosphere, residence time and additives (NH3 and methanol) on NOx (NO and NO2) and SO2 conversion rate was also experimentally evaluated. The results indicated that the new system could greatly promote the NOx conversion rate. As for SO2, the new system only had a slight influence. High temperature suppressed the NO oxidization and slightly promoted the SO2 oxidation. The long residence time was beneficial to the NOx and SO2 oxidization. In the absence of water, the additive of NH3 can improve NO, NOx and SO2 oxidization rate due to the reactions between NH3 and NOx or SO2. Contrary to NH3, methanol had a negative effect on NOx and SO2 oxidization. Copyright 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]