scholarly journals Thermal Metamorphism on the Moon as Recorded by the Granulite Suite

2021 ◽  
pp. jgs2021-044
Author(s):  
John F. Pernet-Fisher ◽  
Katherine H. Joy
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Thermal Conditions ◽  
Heat Sources ◽  
The Moon ◽  
Lunar Crust ◽  
Content Type ◽  
Thermal Metamorphism ◽  
Lunar Meteorite ◽  
Supplementary Material

Thermally metamorphosed rocks on the Moon are an important, yet under-studied suite of lithologies that have been identified within the Apollo and lunar meteorite collections. These rocks, with granoblastic and poikilitic textures, are generally referred to as granulites. However, unlike their terrestrial counterparts which are the metamorphic products of both high temperatures and pressures, lunar granulites are thought to be the products of only high-temperature (> 1000 oC) thermal metamorphism that completely recrystallised their protoliths. We summarise the range of textures and chemical systematics reported from lunar granulites. These data enable constraints to be placed on the thermal conditions in the lunar crust required for high-temperature metamorphism to have taken place. Most studies indicate that impact melt sheets have the relevant thermal properties to sustain high temperatures over the time scales required to fully recrystallise surrounding crustal lithologies. However, the roles of alternative heat sources, such as magmatic intrusions into the crust, have not been extensively investigated and, as such, cannot be ruled out. Additionally, chemical data yields important insights into the protoliths of the granulite suite. By identifying protoliths, we greatly enhance our understanding of the range of lithologies that make up the primary lunar crust. In turn, this enables crustal formation models to be better constrained.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5623326

scholarly journals Insights into the Maturation of Pernisine, a Subtilisin-Like Protease from the Hyperthermophilic Archaeon Aeropyrum pernix

2020 ◽  
Vol 86 (17) ◽  
Author(s):  
Miha Bahun ◽  
Marko Šnajder ◽  
Dušan Turk ◽  
Nataša Poklar Ulrih
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Catalytic Domain ◽  
Industrial Applications ◽  
Binding Motif ◽  
Content Type ◽  
Hyperthermophilic Archaeon ◽  
Aeropyrum Pernix ◽  
Autocatalytic Process ◽  
Exceptional Stability

ABSTRACT Pernisine is a subtilisin-like protease that was originally identified in the hyperthermophilic archaeon Aeropyrum pernix, which lives in extreme marine environments. Pernisine shows exceptional stability and activity due to the high-temperature conditions experienced by A. pernix. Pernisine is of interest for industrial purposes, as it is one of the few proteases that has demonstrated prion-degrading activity. Like other extracellular subtilisins, pernisine is synthesized in its inactive pro-form (pro-pernisine), which needs to undergo maturation to become proteolytically active. The maturation processes of mesophilic subtilisins have been investigated in detail; however, less is known about the maturation of their thermophilic homologs, such as pernisine. Here, we show that the structure of pro-pernisine is disordered in the absence of Ca2+ ions. In contrast to the mesophilic subtilisins, pro-pernisine requires Ca2+ ions to adopt the conformation suitable for its subsequent maturation. In addition to several Ca2+-binding sites that have been conserved from the thermostable Tk-subtilisin, pernisine has an additional insertion sequence with a Ca2+-binding motif. We demonstrate the importance of this insertion for efficient folding and stabilization of pernisine during its maturation. Moreover, analysis of the pernisine propeptide explains the high-temperature requirement for pro-pernisine maturation. Of note, the propeptide inhibits the pernisine catalytic domain more potently at high temperatures. After dissociation, the propeptide is destabilized at high temperatures only, which leads to its degradation and finally to pernisine activation. Our data provide new insights into and understanding of the thermostable subtilisin autoactivation mechanism. IMPORTANCE Enzymes from thermophilic organisms are of particular importance for use in industrial applications, due to their exceptional stability and activity. Pernisine, from the hyperthermophilic archaeon Aeropyrum pernix, is a proteolytic enzyme that can degrade infective prion proteins and thus has a potential use for disinfection of prion-contaminated surfaces. Like other subtilisin-like proteases, pernisine needs to mature through an autocatalytic process to become an active protease. In the present study, we address the maturation of pernisine and show that the process is regulated specifically at high temperatures by the propeptide. Furthermore, we demonstrate the importance of a unique Ca2+-binding insertion for stabilization of mature pernisine. Our results provide a novel understanding of thermostable subtilisin autoactivation, which might advance the development of these enzymes for commercial use.

High temperature mechanical properties of steel bars available in Pakistan

2018 ◽  
Vol 9 (3) ◽  
pp. 203-221 ◽  
Author(s):  
Muhammad Masood Rafi ◽  
Abdul Basit Dahar ◽  
Tariq Aziz
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Ambient Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Experimental Testing ◽  
Local Market ◽  
Content Type ◽  
Yield Plateau ◽  
Steel Bars

Purpose The purpose of this paper is to present the results of experimental testing of steel rebars at elevated temperatures. Three types of bars available in the local market in Pakistan were used. These data are not available in Pakistan. Design/methodology/approach Three types of bars were used, which included cold-twisted ribbed (CTR), hot-rolled deformed (HRD) and thermo-mechanically treated (TMT) bars. The diameter of the bar of each type was 16 mm. The bars were heated in an electrical furnace at temperatures which were varied from 100°C to 900°C in increment of 100°C. Bars of each type were also tested at ambient temperature as control specimens. The change of strength, strain and modulus of elasticity of the bars at high temperatures were determined. Findings The mechanical properties of the bars were nearly unaffected by the temperatures up to 200°C. CTR bars did not show yield plateau and strain hardening both at ambient and high temperatures. The high temperature yield strength and elastic modulus for all the three types of bars were similar at all temperatures. The yield plateau of both the HRD and TMT bars disappeared at temperatures greater than 300°C. The ultimate strength at high temperature of the HRD and TMT bars was also similar. The behaviours of the HRD and TMT bars changed to brittle beyond 400°C as compared to their behaviours at ambient temperature. The CTR bars exhibited ductile characteristics at failure at all the exposure temperatures relative to their behaviour at ambient temperature. Research limitations/implications The parameters of the paper included the rebar type and heating temperature and the effects of temperature on strength and stiffness properties of the steel bars. Practical implications Building fire incidents have increased in Pakistan. As reinforced concrete (RC) buildings exist in the country in significant numbers, the data related to elevated temperature properties of steel is required. These data are not available in Pakistan presently. The presented paper aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members. Originality/value The presented paper is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of steel reinforcing bars available in Pakistan.

High-transconductance silicon carbide nanowire-based field-effect transistor (SiC-NWFET) for high-temperature applications

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Habeeb Mousa ◽  
Kasif Teker
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Field Effect Transistor ◽  
High Electron ◽  
Si Substrate ◽  
Content Type ◽  
Nitrogen Doped ◽  
Sic Nanowires ◽  
Effect Transistor ◽  
High Transconductance

Purpose The purpose of this study is to present a systematic investigation of the effect of high temperatures on transport characteristics of nitrogen-doped silicon carbide nanowire-based field-effect transistor (SiC-NWFET). The 3C-SiC nanowires can endure high-temperature environments due to their wide bandgap, high thermal conductivity and outstanding physical and chemical properties. Design/methodology/approach The metal-organic chemical vapor deposition process was used to synthesize in-situ nitrogen-doped SiC nanowires on SiO2/Si substrate. To fabricate the proposed SiC-NWFET device, the dielectrophoresis method was used to integrate the grown nanowires on the surface of pre-patterned electrodes onto the SiO2 layer on a highly doped Si substrate. The transport properties of the fabricated device were evaluated at various temperatures ranging from 25°C to 350°C. Findings The SiC-NWFET device demonstrated an increase in conductance (from 0.43 mS to 1.2 mS) after applying a temperature of 150°C, and then a decrease in conductance (from 1.2 mS to 0.3 mS) with increasing the temperature to 350°C. The increase in conductance can be attributed to the thermionic emission and tunneling mechanisms, while the decrease can be attributed to the phonon scattering. Additionally, the device revealed high electron and hole mobilities, as well as very low resistivity values at both room temperature and high temperatures. Originality/value High-temperature transport properties (above 300°C) of 3C-SiC nanowires have not been reported yet. The SiC-NWFET demonstrates a high transconductance, high electron and hole mobilities, very low resistivity, as well as good stability at high temperatures. Therefore, this study could offer solutions not only for high-power but also for low-power circuit and sensing applications in high-temperature environments (∼350°C).

scholarly journals Scenario-based hazard analysis of extreme high-temperatures experienced between 1959 and 2014 in Hulunbuir, China

2019 ◽  
Vol 11 (1) ◽  
pp. 2-17
Author(s):  
Chunlan Li ◽  
Jun Wang ◽  
Min Liu ◽  
Desalegn Yayeh Ayal ◽  
Qian Gong ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Mitigation Strategies ◽  
Significant Feature ◽  
Environmental Damage ◽  
Fluctuation Analysis ◽  
Research Attention ◽  
Content Type ◽  
Extreme High Temperature ◽  
High Hazard

Purpose Extreme high temperatures are a significant feature of global climate change and have become more frequent and intense in recent years. These pose a significant threat to both human health and economic activity, and thus are receiving increasing research attention. Understanding the hazards posed by extreme high temperatures are important for selecting intervention measures targeted at reducing socioeconomic and environmental damage. Design/methodology/approach In this study, detrended fluctuation analysis is used to identify extreme high-temperature events, based on homogenized daily minimum and maximum temperatures from nine meteorological stations in a major grassland region, Hulunbuir, China, over the past 56 years. Findings Compared with the commonly used functions, Weibull distribution has been selected to simulate extreme high-temperature scenarios. It has been found that there was an increasing trend of extreme high temperature, and in addition, the probability of its indices increased significantly, with regional differences. The extreme high temperatures in four return periods exhibited an extreme low hazard in the central region of Hulunbuir, and increased from the center to the periphery. With the increased length of the return period, the area of high hazard and extreme high hazard increased. Topography and anomalous atmospheric circulation patterns may be the main factors influencing the occurrence of extreme high temperatures. Originality/value These results may contribute to a better insight in the hazard of extreme high temperatures, and facilitate the development of appropriate adaptation and mitigation strategies to cope with the adverse effects.

Performance Analysis of a Cascading Adsorption Cycle Powered by High-Temperature Heat Sources for Low-Temperature Cooling in Hot Climates

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Dalila Abbaz ◽  
Abla Chaker ◽  
Mahmoud Bourouis
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Thermal Conditions ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Heat Sources ◽  
Adsorption Refrigeration ◽  
Temperature Heat ◽  
Adsorption Cycle

Abstract Cascade adsorption refrigeration technology using high-temperature driving heat is a very promising option for low-temperature cooling applications due to the large temperature difference between the heat source and the cold distributed. The present work carried out a feasibility and parametric study in order to analyze the functioning of a cascading adsorption cycle using the working pair zeolite/ammonia in beds operating at high temperatures and activated carbon/ammonia in those operating at low temperatures. At the nominal thermal conditions, namely, heating, condensing, and evaporating temperatures of 280 °C, 35 °C, and (−5) °C, respectively, the coefficient of performance (COP) and the specific refrigerating capacity (SCP) of the cycle were 0.53 and 67.1 W/kg. When the driving temperature is varied from 260 °C to 320 °C, the COP increases by 57% and the SCP by 36%. The performance of the cascading adsorption cycle at negative evaporating temperatures is very satisfactory.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

NICROFER 5520 Co

Alloy Digest ◽  
1995 ◽  
Vol 44 (3) ◽  
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Temperatures ◽  
Heat Treating ◽  
High Temperature Corrosion ◽  
Creep Properties ◽  
Nickel Chromium ◽  
Temperature Performance

Abstract NICROFER 5520 Co is a nickel-chromium-cobalt-molybdenum alloy with excellent strength and creep properties up to high temperatures. Due to its balanced chemical composition the alloy shows outstanding resistance to high temperature corrosion in the form of oxidation and carburization. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ni-480. Producer or source: VDM Technologies Corporation.

CARLSON ALLOY C601

Alloy Digest ◽  
1994 ◽  
Vol 43 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
High Temperatures ◽  
Stress Corrosion Cracking ◽  
Heat Treating ◽  
Resistance To Stress ◽  
Extended Exposure ◽  
Sulfur Containing

Abstract Carlson Alloy C601 is characterized by high tensile, yield and creep-rupture strengths for high temperature service. The alloy is not embrittled by extended exposure to high temperatures and has excellent resistance to stress-corrosion cracking, to carburizing, nitriding and sulfur containing environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, and joining. Filing Code: Ni-458. Producer or source: G.O. Carlson Inc.

INCOTHERM TD

Alloy Digest ◽  
2005 ◽  
Vol 54 (11) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Rare Earths ◽  
Temperature Performance

Abstract Incotherm TD is a thermocouple-sheathing alloy with elements of silicon and rare earths to enhance oxidation resistance at high temperatures. This datasheet provides information on composition, physical properties, and tensile properties as well as deformation. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-628. Producer or source: Special Metals Corporation.

HASTELLOY ALLOY X

Alloy Digest ◽  
1954 ◽  
Vol 3 (12) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Heat Treating ◽  
Operating Conditions ◽  
Molybdenum Alloy ◽  
High Temperature Strength ◽  
Nickel Chromium

Abstract HASTELLOY Alloy X is a nickel-chromium-iron-molybdenum alloy recommended for high-temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on forming, heat treating, and machining. Filing Code: Ni-14. Producer or source: Haynes Stellite Company.

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