Conduction and Hall measurements ofBa2YCu3O6+δfilms at high temperatures: The role of oxygen

1988 ◽  
Vol 38 (4) ◽  
pp. 2828-2831 ◽  
Author(s):  
A. Davidson ◽  
P. Santhanam ◽  
A. Palevski ◽  
M. J. Brady
Keyword(s):  
High Temperatures ◽  
Hall Measurements

scholarly journals Molecular Dynamics of Chloroplast Membranes Isolated from Wild-Type Barley and a Brassinosteroid-Deficient Mutant Acclimated to Low and High Temperatures

Biomolecules ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Iwona Sadura ◽  
Dariusz Latowski ◽  
Jana Oklestkova ◽  
Damian Gruszka ◽  
Marek Chyc ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Temperature Stress ◽  
High Temperatures ◽  
Biological Membrane ◽  
Hydrophobic Core ◽  
Wild Type ◽  
Chloroplast Membranes ◽  
Paramagnetic Resonance ◽  
Photosynthetic Membranes

Plants have developed various acclimation strategies in order to counteract the negative effects of abiotic stresses (including temperature stress), and biological membranes are important elements in these strategies. Brassinosteroids (BR) are plant steroid hormones that regulate plant growth and development and modulate their reaction against many environmental stresses including temperature stress, but their role in modifying the properties of the biological membrane is poorly known. In this paper, we characterise the molecular dynamics of chloroplast membranes that had been isolated from wild-type and a BR-deficient barley mutant that had been acclimated to low and high temperatures in order to enrich the knowledge about the role of BR as regulators of the dynamics of the photosynthetic membranes. The molecular dynamics of the membranes was investigated using electron paramagnetic resonance (EPR) spectroscopy in both a hydrophilic and hydrophobic area of the membranes. The content of BR was determined, and other important membrane components that affect their molecular dynamics such as chlorophylls, carotenoids and fatty acids in these membranes were also determined. The chloroplast membranes of the BR-mutant had a higher degree of rigidification than the membranes of the wild type. In the hydrophilic area, the most visible differences were observed in plants that had been grown at 20 °C, whereas in the hydrophobic core, they were visible at both 20 and 5 °C. There were no differences in the molecular dynamics of the studied membranes in the chloroplast membranes that had been isolated from plants that had been grown at 27 °C. The role of BR in regulating the molecular dynamics of the photosynthetic membranes will be discussed against the background of an analysis of the photosynthetic pigments and fatty acid composition in the chloroplasts.

The role of acetic acid in FeCO3 scale deposition on CO2 corrosion of API X65 carbon steel under high temperatures

2021 ◽  
pp. 1-12
Author(s):  
Bernardo Augusto Farah Santos ◽  
Rhuan Costa Souza ◽  
Maria Eduarda Dias Serenario ◽  
Eugenio Pena Mendes Junior ◽  
Thiago Araujo Simões ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Carbon Steel ◽  
High Temperatures ◽  
Co2 Corrosion ◽  
Scale Deposition

Model thermodynamics and the role of free-carrier energy at high temperatures: Nitrogen and boron pairing in diamond

2009 ◽  
Vol 80 (5) ◽  
Author(s):  
R. M. MacLeod ◽  
S. W. Murray ◽  
J. P. Goss ◽  
P. R. Briddon ◽  
R. J. Eyre
Keyword(s):  
High Temperatures ◽  
Free Carrier ◽  
Carrier Energy

The Role of Leaf Epicuticular Wax in the Adaptation of Wheat ( Triticum aestivum L.) to High Temperatures and Moisture Deficit Conditions

Crop Science ◽  
2018 ◽  
Vol 58 (2) ◽  
pp. 679-689 ◽  
Author(s):  
Suheb Mohammed ◽  
Trevis D. Huggins ◽  
Francis Beecher ◽  
Chris Chick ◽  
Padma Sengodon ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
High Temperatures ◽  
Triticum Aestivum L ◽  
Epicuticular Wax ◽  
Moisture Deficit ◽  
Leaf Epicuticular Wax

Physiological and morphological effects of climate change

2019 ◽  
pp. 120-133 ◽  
Author(s):  
Andrew E. McKechnie
Keyword(s):  
Climate Change ◽  
Body Mass ◽  
High Temperatures ◽  
Arid Zone ◽  
Future Research ◽  
Long Term Effects ◽  
Adaptation To Climate Change ◽  
Heat Events

The direct impacts of higher temperatures on birds are manifested over timescales ranging from minutes and hours to years and decades. Over short timescales, acute exposure to high temperatures can lead to hyperthermia or dehydration, which among arid-zone species occasionally causes catastrophic mortality events. Over intermediate timescales of days to weeks, high temperatures can have chronic sub-lethal effects via body mass loss or reduced nestling growth rates, negatively affecting sev eral fitness components. Long-term effects of warming manifested over years to decades involve declining body mass or changes in appendage size. Key directions for future research include elucidating the role of phenotypic plasticity and epigenetic processes in avian adaptation to climate change, examining the role of stress pathways in mediating responses to heat events, and understanding the consequences of higher temperatures for species that traverse hot regions while migrating.

The role of calcium diffusion on high temperature SO2 uptake by volcanic glasses

2020 ◽  
Author(s):  
Ana S. Casas ◽  
Fabian B. Wadsworth ◽  
Paul M. Ayris ◽  
Pierre Delmelle ◽  
Jérémie Vasseur ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Volcanic Glass ◽  
Explosive Eruptions ◽  
Preferential Formation ◽  
Fe Content ◽  
Potentiometric Titration Method ◽  
Sulfate Salts ◽  
Surficial Deposits

<p>Glass-SO₂ reactions occurring at high temperatures in (terrestrial and extraterrestrial) volcanic environments have received increasing attention in the past years (e.g., Renggli and King 2018; Casas et al. 2019; Renggli et al. 2019), based on both natural and experimental observations. Laboratory studies carried out at high temperatures (>200 °C) demonstrate that volcanic glass in the presence of SO₂ reacts to form surficial sulfate-bearing minerals (e.g., Ayris et al. 2013; Delmelle et al. 2018), mostly calcium sulfate salts (CaSO₄). Thus, high temperature glass-SO₂ interaction acts as a sink for the magmatic S released during explosive volcanic activity, potentially impacting the S budget of large explosive eruptions. Here, we present the results of new experiments aimed at assessing the influence of the glass Ca content on SO<sub>2</sub> uptake in the temperature range of 600-800 °C. We exposed haplogranitic glasses to SO₂ for diverse time exposures (5-30 minutes). Rhyolitic composition was chosen due to the ubiquity of Si-rich magmas in large explosive eruptions (Cioni et al. 2000).</p><p>The experimental glasses were synthesized with an initial HPG8 composition (see Holtz et al. 1992), doped with 1 and 2 wt.% CaO. Furthermore, the role of Fe was tested by doping the glasses with 0, 0.1, 1, 1.5, 2 and 2.5 wt.% FeO and equilibrating them at 1500 °C. Leachates of post-treated glasses were analyzed by ion chromatography in order to determine SO<sub>2</sub>-uptake and the nature of the sulfate-bearing minerals formed by solid-gas reactions. The bulk redox state of iron (Fe³⁺/Fe<sub>total</sub>), was obtained by the K₂Cr₂O₇ potentiometric titration method. Our results show a strong correlation between the amount of Ca in the glasses and the formation of CaSO₄ surficial deposits (i.e. SO₂ uptake), i.e. the HPG8 + 2 wt.% CaO treated samples produced up to 40 % more CaSO₄ than the samples containing 1 wt.% CaO. Higher Fe content in the glass also enhanced formation of CaSO₄. In contrast, the absence of Fe oxide resulted in preferential formation of Na₂SO₄ and K₂SO₄, when compared to the Fe-bearing specimens. Our experiments confirm that high temperature SO₂ uptake by glass is strongly dependent on the Ca content and temperature, with the optimal reaction temperatures being ≥600 °C. Increasing the amount of FeO in the glasses seems to enhance SO<sub>2</sub> uptake, although this effect appears to be different for Ca than for Na or K, pointing out a more complex influence of redox dynamics on cation diffusion.</p><p> </p>

scholarly journals Role of HtrA in the Virulence and Competence of Streptococcus pneumoniae

2004 ◽  
Vol 72 (6) ◽  
pp. 3584-3591 ◽  
Author(s):  
Yasser Musa Ibrahim ◽  
Alison R. Kerr ◽  
Jackie McCluskey ◽  
Tim J. Mitchell
Keyword(s):  
Oxidative Stress ◽  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Mouse Models ◽  
High Temperatures ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Wild Type ◽  
Major Virulence Factor

ABSTRACT HtrA is a major virulence factor of Streptococcus pneumoniae (the pneumococcus). Deletion of the gene for HtrA from strain D39 of the pneumococcus completely abolished its virulence in mouse models of pneumonia and bacteremia, while the virulence of a second strain (TIGR4) was dramatically reduced. HtrA-negative mutants induced much less inflammation in the lungs during pneumonia than the wild type. HtrA is involved in the ability of the pneumococcus to grow at high temperatures, to resist oxidative stress, and to undergo genetic transformation. The expression and cellular location of several known virulence factors of the pneumococcus were not affected by the lack of HtrA.

VORTICES IN HIGH-TEMPERATURE STRING THEORY

1989 ◽  
Vol 04 (11) ◽  
pp. 1063-1067 ◽  
Author(s):  
G. CHAPLINE ◽  
F.R. KLINKHAMER
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
High Temperature ◽  
String Theory ◽  
High Temperatures ◽  
World Sheet ◽  
Genus Zero ◽  
Mass Gap ◽  
The World

We discuss the role of XY-like vortices on the world-sheet for the free energy of strings at high temperatures. There is a Kosterlitz-Thouless phase transition at the Hagedorn temperature, above which the vortices contribute to the free energy in genus zero and generate a mass gap. We speculate that high-temperature “string” theory could be essentially discrete.

The Role of the Haemocytes in the Growth and Moulting of an Insect, Rhodnius Prolixus (Hemiptera)

1955 ◽  
Vol 32 (4) ◽  
pp. 649-663
Author(s):  
V. B. WIGGLESWORTH
Keyword(s):  
High Temperatures ◽  
Blood Cells ◽  
Trypan Blue ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Crystalline Material ◽  
The Other ◽  
Full Activity ◽  
Other Hand

Moulting in Rhodnius is greatly delayed by the injection of trypan blue, indian ink or iron saccharate, which are taken up by the phagocytic blood cells (amoebocytes). This delay occurs only when the injections are made during the first 3 days after feeding, not on the fourth day or later. On the fourth day after feeding the amoebocytes become filled with secretory vacuoles which restrict the uptake of indian ink or iron saccharate. When the amoebocytes are blocked by such injections within a day after feeding, the secretory activity of the thoracic gland is greatly reduced. This is proved histologically and experimentally. On the other hand, moulting induced by implantation of a fully active thoracic gland is not delayed by blocking the haemocytes. It is therefore concluded that some substance secreted by the haemocytes is necessary for the full activity of the thoracic glands. The crystalline hormone isolated by Butenandt & Karlson from the silkworm will induce moulting in the decapitated Rhodnius larva and in the isolated abdomen. Its action is not inhibited or delayed by the injection of indian ink or iron saccharate. This supports the conclusion that it is the product of the thoracic gland. Sublethal high temperatures will inhibit moulting in Rhodnius even when it is provided with abundant hormone by injection of the crystalline material or by joining in parabiosis with a moulting larva.

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