scholarly journals The Physiological Action of Abnormally High Temperatures on Poikilotherm Animals

1940 ◽  
Vol 17 (4) ◽  
pp. 386-395
Author(s):  
G. S. FRAENKEL ◽  
G. V. B. HERFORD
Keyword(s):  
Oxygen Consumption ◽  
High Temperature ◽  
Partial Pressure ◽  
High Temperatures ◽  
Oxygen Pressure ◽  
Partial Pressure Of Oxygen ◽  
Waste Products ◽  
Physiological Action ◽  
Very High ◽  
Acid Waste

The oxygen consumption of blowfly larvae at sublethal and lethal high temperatures at the beginning of the determination is entirely dependent on the oxygen pressure, but after about 1 hr. at 42°C. it is higher at 20 and 10% partial pressure of oxygen than at either 100 or 5%. Death at high temperatures is not due to lack of oxygen, but may be due to the accumulation of acid waste products of the metabolism. The basal oxygen consumption remains unchanged for some time after the organism has been irreversibly injured by the high temperature. Blowfly larvae resist the damaging effect of high temperatures slightly better in air (20% oxygen) than in either very high (100%) or very low (less than 10%) concentrations of oxygen.

Characteristics and aging of SiC MOSFETs operated at very high temperatures

2014 ◽  
Vol 1693 ◽  
Author(s):  
Dean P. Hamilton ◽  
Michael R. Jennings ◽  
Craig A. Fisher ◽  
Yogesh K. Sharma ◽  
Stephen J. York ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Threshold Voltage ◽  
Thermal Aging ◽  
Ohmic Contacts ◽  
Stress Tests ◽  
Temperature Capability ◽  
Temperature Constant ◽  
Voltage Management ◽  
Very High

ABSTRACTSilicon carbide power devices are purported to be capable of operating at very high temperatures. Current commercially available SiC MOSFETs from a number of manufacturers have been evaluated to understand and quantify the aging processes and temperature dependencies that occur when operated up to 350°C. High temperature constant positive bias stress tests demonstrated a two times increase in threshold voltage from the original value for some device types, which was maintained indefinitely but could be corrected with a long negative gate bias. The threshold voltages were found to decrease close to zero and the on-state resistances increased quite linearly to approximately five or six times their room temperature values. Long term thermal aging of the dies appears to demonstrate possible degradation of the ohmic contacts. This appears as a rectifying response in the I-V curves at low drain-source bias. The high temperature capability of the latest generations of these devices has been proven independently; provided that threshold voltage management is implemented, the devices are capable of being operated and are free from the effects of thermal aging for at least 70 hours cumulative at 300°C.

scholarly journals Forging, textures, and deformation systems in a B2 FeAl alloy

1999 ◽  
Vol 14 (3) ◽  
pp. 715-728 ◽  
Author(s):  
P. Zhao ◽  
D. G. Morris ◽  
M. A. Morris Munoz
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Slip System ◽  
High Temperatures ◽  
Low Temperatures ◽  
High Speed ◽  
Deformation Texture ◽  
Slip Systems ◽  
Feal Alloy ◽  
Very High

High-temperature forging experiments have been carried out by axial compression testing on a Fe–41Al–2Cr alloy in order to determine the deformation systems operating under such high-speed, high-temperature conditions, and to examine the textures produced by such deformation and during subsequent annealing to recrystallize. Deformation is deduced to take place by the operation of 〈111〉 {110} and 〈111〉{112} slip systems at low temperatures and by 〈100〉{001} and 〈100〉{011} slip systems at high temperatures, with the formation of the expected strong 〈111〉 textures. The examination of the weak 〈100〉 texture component is critical to distinguishing the operating slip system. Both texture and dislocation analyses are consistent with the operation of these deformation systems. Recrystallization takes place extremely quickly at high temperatures (above 800 °C), that is within seconds after deformation and also dynamically during deformation itself. Recrystallization changes the texture such that 〈100〉 textures superimpose on the deformation texture. The flow stress peak observed during forging is found at a very high temperature. Possible origins of the peak are examined in terms of the operating slip systems.

Integrity assessment of the high temperature engineering test reactor (HTTR) control rod at very high temperatures

1997 ◽  
Vol 172 (1-2) ◽  
pp. 93-102 ◽  
Author(s):  
Y. Tachibana ◽  
S. Shiozawa ◽  
J. Fukakura ◽  
F. Matsumoto ◽  
T. Araki
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Control Rod ◽  
Integrity Assessment ◽  
Test Reactor ◽  
Very High

THE EFFECT OF TEMPERATURE ON THE CRITICAL OXYGEN PRESSURE FOR HEART-BEAT FREQUENCY IN EMBRYOS OF ATLANTIC SALMON AND SPECKLED TROUT

1942 ◽  
Vol 20d (1) ◽  
pp. 1-12 ◽  
Author(s):  
Kenneth C. Fisher
Keyword(s):  
Atlantic Salmon ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Critical Pressure ◽  
Beat Frequency ◽  
Heart Beat ◽  
Effect Of Temperature ◽  
Limiting Factor ◽  
Partial Pressure Of Oxygen ◽  
Critical Oxygen

Intact embryos of speckled trout and Atlantic salmon were exposed to solutions of oxygen and nitrogen in distilled water. It was observed that as the partial pressure of oxygen was reduced a pressure was found below which the frequency of the heart-beat was not maintained at the normal level characteristic of higher partial pressures of oxygen. A "critical" partial pressure of oxygen for heart-beat frequency can therefore be said to exist. Data have been obtained from which its value at five different temperatures can be determined. The critical pressures for the two organisms are similar, rising from approximately 3 to 5 mm. of mercury at 1.5 °C. to 40 to 50 mm. of mercury at 20 °C. Possible mechanisms leading to the establishment of a critical oxygen partial pressure are discussed. It seems likely that diffusion is not the limiting factor in these preparations so that the critical pressure, and its temperature coefficient, must be the property of the intracellular respiratory systems concerned. The finding that the logarithm of the critical partial pressure can be represented as a linear function of the reciprocal of the absolute temperature is consistent with this view. Temperature exercises a more pronounced effect on the critical oxygen pressure of the pacemaking process, than it does on the over-all velocity of that process as indicated by the normal frequency of the heart. It is concluded that the critical pressure is a characteristic of the chemical systems in the pace-making cells of the heart.

Applications: Light My Fire

1982 ◽  
Vol 75 (1) ◽  
pp. 53-55
Author(s):  
George Knill ◽  
George Fawceti
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Low Temperatures ◽  
Chemical Process ◽  
Room Temperature ◽  
Very High

Everyone knows that wood bums at a very high temperature. This burning is a chemical process that combines oxygen and carbon. The process occurs at very low temperatures as well as at very high ones. At high temperatures the process is spectacular-fire. At low temperatures (room temperature) you won’t even notice it, although it is still going on. Wood is always burning.

RESPIRATION OF FISHES WITH SPECIAL EMPHASIS ON STANDARD OXYGEN CONSUMPTION: IV. INFLUENCE OF CARBON DIOXIDE AND OXYGEN

1964 ◽  
Vol 42 (5) ◽  
pp. 847-856 ◽  
Author(s):  
F. W. H. Beamish
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Partial Pressure ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Partial Pressure Of Oxygen ◽  
Partial Pressures ◽  
Rate Of Oxygen Consumption ◽  
Standard Rate ◽  
Different Levels

Oxygen consumption was determined in relation to spontaneous activity and standard metabolism estimated by extrapolating the values to zero activity, Standard oxygen consumption was determined in relation to different partial pressures of carbon dioxide and oxygen for brook trout. Salvelinus fontinalis (Mitchill), at 10 °C, and carp, Cyprinus carpio Linnaeus, at 25 °C. In general, at each partial pressure of oxygen applied, standard oxygen consumption did not change significantly over the range of partial pressures of carbon dioxide followed. The relation for brook trout operated on a level characteristic of the partial pressure of oxygen. Although the effect of different levels of oxygen was not established for carp at 25 °C, it is presumed that the relation operated also in that species in a similar way.Acclimation to the different levels of carbon dioxide and oxygen to be tested was examined and, ordinarily, found not to change significantly the standard rate of oxygen consumption.

In-situ Hrem Heating Experiments at Very High Temperatures

1995 ◽  
Vol 404 ◽  
Author(s):  
T. Kamino ◽  
H. Saka
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Atomic Resolution ◽  
Very High

AbstractA specimen-heating holder which allows an observation of reactions of more than one materials, in a controlled manner, at such a high temperature as 1723K has been developed. Facet-unfacet transformation and reconstruction of Au-deposited Si surfaces have been observed at very high temperatures at near-atomic resolution.

PrBa2Cu3Ox Polycrystalline Superconductor Preparation

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3278-3283 ◽  
Author(s):  
W. L. Hults ◽  
J. C. Cooley ◽  
E. J. Peterson ◽  
J. L. Smith ◽  
Howard A. Blackstead ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Partial Pressure ◽  
High Temperatures ◽  
Sintering Temperature ◽  
Weak Ferromagnetism ◽  
Electromagnetic Properties ◽  
Oxygen Level ◽  
Partial Pressure Of Oxygen ◽  
Preparation Conditions

We prepared many samples of nominal PrBa2Cu3O x as ceramic, polycrystalline pellets with an enormous variety of preparation conditions and can confirm its superconductivity at T c = 89 K. We found that the superconductivity is in material with the YBa2Cu3O7 (YBCO) crystal structure. We observed weak ferromagnetism (canted antiferromagnetism) in samples prepared at high temperatures with a low partial pressure of oxygen; these samples also contained the phase PrBaO3 . The electromagnetic properties of the material depend sensitively on preparation conditions, especially the sintering temperature and the oxygen level.

Development of high temperature creep resistance in Fe-Al alloys

2004 ◽  
Vol 842 ◽  
Author(s):  
D. G. Morris ◽  
M. A. Muñoz-Morris ◽  
C. Baudin
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Creep Resistance ◽  
Good Strength ◽  
Thermally Activated ◽  
Intermediate Temperature Range ◽  
Deformation Processes ◽  
Good Creep Resistance ◽  
Oxidation And Corrosion ◽  
Very High

ABSTRACTMost of the studies aimed at the development of creep-resisting Fe-Al intermetallics have been oriented at application temperatures of the order of 500–650°C, where these materials may compete with conventional stainless steels. The Fe-Al intermetallics are, however, particularly excellent in their oxidation and corrosion resistances at temperatures of the order of 1000°C, where Chromium-Nickel steels are no longer able to withstand the aggressive environments. This presentation is part of a study aimed at the development of good creep resistance at such high temperatures.Studies of a variety of cast Fe3Al-base alloys, strengthened by solution or precipitate/dispersoid-forming alloying additions, are reported. The alloys show good strength from room temperature to about 500°C, but thereafter strength falls rapidly as thermally-activated deformation processes become operative. Solution additions are capable of producing good low temperature strength, but do not contribute significantly to creep strength at very high temperatures (above 700°C). Precipitation hardening has been examined in Nb-containing alloys, where Fe2Nb Laves precipitates form at intermediate temperatures. These materials show good strength up to about 700°C, but at higher temperatures the fine precipitates coarsen excessively. Strengthening in the intermediate temperature range varies depending on whether the solute is precipitated prior to high temperature testing or concurrent with this.

COLUMBIUM D-31

Alloy Digest ◽  
1963 ◽  
Vol 12 (3) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tensile Properties ◽  
High Temperatures ◽  
Base Alloy ◽  
Density Ratio ◽  
Heat Treating ◽  
Temperature Performance ◽  
Very High

Abstract COLUMBIUM D-31 is a columbium-base alloy that maintains its stability at very high temperatures. It is 5 times as resistant to oxidation as pure columbium and about 100 times as resistant as molybdenum. Its strength to density ratio at 2000 F (stress relieved) is 77400. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-4. Producer or source: E. I. Dupont de Nemours & Company Inc..

Sign in / Sign up

Export Citation Format

Share Document