scholarly journals SOUND VELOCITY AND SOUND ABSORPTION IN THE CRITICAL TEMPERATURE REGION

1951 ◽  
Vol 29 (3) ◽  
pp. 243-252 ◽  
Author(s):  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Liquid Phase ◽  
Sound Velocity ◽  
Temperature Region ◽  
Temperature Range ◽  
Maximum Value ◽  
Increasing Temperature ◽  
Very High ◽  
High Absorption ◽  
Liquid And Vapor Phases

The velocity and absorption of ultrasound (600 kc.) has been measured throughout the critical temperature region of sulphur hexafluoride. Measurements were carried out for the coexisting liquid phase and vapor phase below Tc, and for the supercritical gas, and simultaneously, observations of the meniscus behavior in the neighborhood of Tc were made. The sound velocity for both liquid and vapor phases below Tc decreased with increasing temperature and became equal at Tc, the velocity at this point being 121.5 m. per sec. In the temperature range from 0.6° below Tc to Tc the velocity in the vapor was greater than that in the liquid. A very high absorption of sound was observed, having a maximum value at Tc and extending over a temperature range of approximately 1°. In the temperature range from Tc to 0.6° below Tc, the absorption in the liquid phase was greater than that in the vapour.

Studies On The Intermetallic Semiconductor RuAl2

1998 ◽  
Vol 512 ◽  
Author(s):  
V. Ponnambalam ◽  
U. V. Varadaraju
Keyword(s):  
Electric Power ◽  
Figure Of Merit ◽  
Ladder Structure ◽  
Thermo Electric ◽  
Temperature Range ◽  
Arc Melting ◽  
Maximum Value ◽  
Melting Technique ◽  
Increasing Temperature ◽  
Power Measurements

ABSTRACTThe intermetallic compound RuAl2 with Nowotny chimney-ladder structure is synthesized using arc melting technique. The electrical resistity and thermo electric power measurements were carried out in the temperature range 300–1000K. The resistivity increases with increasing temperature and reaches a maximum value at about 700K. Thermo electric power (TEP) of the sample is negative and the value is about -80 µV/K at RT. The value increases with increasing temperature reaching a maximum value of -140 µV/K at about 600K. The compound exhibits temperature independent power factor in the temperature range 300–550K The calculated figure of merit 1.3 × K-1 is comparable to 7 × 10-4 K-1 of Si-Ge alloys which are used as high temperature thermoelectric materials.

Friction on Wet Surfaces of Tire-Tread-Type Vulcanizates

1964 ◽  
Vol 37 (4) ◽  
pp. 878-893 ◽  
Author(s):  
Barbara E. Sabey ◽  
G. N. Lupton
Keyword(s):  
Skid Resistance ◽  
Correct Interpretation ◽  
Temperature Range ◽  
The Road ◽  
Test Conditions ◽  
Maximum Value ◽  
Rubber Compounds ◽  
Materials Used ◽  
Increasing Temperature ◽  
Styrene Butadiene

Abstract A laboratory investigation has been made into the variation with temperature of the hardness and resilience of a wide variety of rubber compounds of the tire tread type. The effect of hardness and resilience on the fractional properties of the compounds under wet conditions has also been studied. In the first series of tests the resilience and hardness of 25 compounds were measured over a temperature range 0° to 80° C. All were vulcanized tire tread type compounds, and the basic materials used comprised 14 natural rubbers, 7 styrene/butadiene (SBR) rubbers, 2 butyl, 1 polybutadiene, and 1 ethylene/propylene. The tests showed a marked increase in resilience with increasing temperature for all compounds except the polybutadiene; the hardness of all compounds changed very little with temperature, only a slight decrease being observed over the whole temperature rise. Nine compounds of representative resilience and hardness were selected for a second series of tests in which friction was measured over a temperature range 1° to 40° C on seven surfaces representing roads of different textures. For eight of the compounds, friction values decreased with increase in temperature; for the other compound the friction increased to a maximum value at 30° C. These changes in friction cannot be explained by changes in hardness of the compounds, but they are in accordance with resilience changes, taking into account the different test conditions obtaining in the friction and resilience tests. The friction tests also showed that with the portable skid-resistance tester used to measure friction the sharpness of the projections in the road surface is more important than their size in determining the friction values under wet conditions, even when rubber compounds of low resilience are used. The implications of the findings and their application to the study of friction between tire and road are discussed. In particular, they have a bearing on the correct interpretation of resilience measurements of tire tread materials in relation to friction values under wet conditions.

ISOTHERMS OF SULPHUR HEXAFLUORIDE IN THE CRITICAL TEMPERATURE REGION

1951 ◽  
Vol 29 (8) ◽  
pp. 699-714 ◽  
Author(s):  
K. E. MacCormack ◽  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Temperature Region ◽  
Critical Density ◽  
Sulphur Hexafluoride ◽  
Small Temperature ◽  
Liquid Meniscus ◽  
Temperature Range ◽  
Horizontal Portion ◽  
Theoretical Considerations ◽  
Finite Slope

Measurements of the P-V isotherms for sulphur hexafluoride in a small temperature range of approximately 1.5°C. in the critical region have been made to determine the validity of some theoretical considerations recently proposed. No evidence has been found to support the postulates of Mayer with respect to anomalous second order transitions over a finite temperature range above the temperature of disappearance of a liquid meniscus designated Tm. All isotherms above the latter are found to have a finite slope and it is not possible to conclude that the Tm isotherm has a finite horizontal portion or "flat top". These conclusions are borne out by the nature of the isometrics which have been plotted and discussed qualitatively in relation to the existing theories.The temperature of meniscus disappearance Tm is estimated to be 45.547 ± 0.003°C. and at the previously determined critical density (1) of 0.7517 gm./cm.3 the corresponding pressure is found to be 37.113 ± 0.003 atm. The critical density was found to be approximately 0.73 gm./cm.3

Density of Perfluorohexane Near the Evaporation Critical Point

2013 ◽  
Vol 8 (1) ◽  
pp. 73-77
Author(s):  
Sergey Stankus ◽  
Rashid Khairulin ◽  
Viktor Martynets ◽  
Yuri Molorodov
Keyword(s):  
Critical Temperature ◽  
Critical Exponent ◽  
Temperature Dependence ◽  
Critical Point ◽  
Gamma Ray ◽  
Coexistence Curve ◽  
Temperature Range ◽  
Gamma Ray Attenuation ◽  
Liquid And Vapor Phases

The density of n-perfluorohexane along the liquid-vapour coexistence curve has been studied by a gamma-ray attenuation technique over the temperature range from 293.83 to 449.18 K. The critical temperature 449.22  0.05 K, the density 613.8  2 kg/m3 , and the critical exponent of coexistence curve 0.349  0.005 were determined. The approximation equations of the temperature dependence of the liquid and vapor phases density were obtained. The results were compared with the data available in the literature. The influence of hydrostatic effect due to the high compressibility of the substance in the vicinity of the vaporization critical point was observed

scholarly journals Cell mechanical properties of human breast carcinoma cells depend on temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christian Aermes ◽  
Alexander Hayn ◽  
Tony Fischer ◽  
Claudia Tanja Mierke
Keyword(s):  
Mechanical Properties ◽  
Power Law ◽  
Cell Mechanics ◽  
Cell Types ◽  
Creep Response ◽  
Temperature Range ◽  
Myosin Filaments ◽  
Cell Mechanical Properties ◽  
Increasing Temperature ◽  
Mcf 7

AbstractThe knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell’s cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.

Critical constants and density dependence of the Lorenz–Lorentz coefficient for germane

1978 ◽  
Vol 56 (9) ◽  
pp. 1140-1141 ◽  
Author(s):  
P. Palffy-Muhoray ◽  
D. Balzarini
Keyword(s):  
Critical Temperature ◽  
Density Dependence ◽  
Experimental Error ◽  
Critical Density ◽  
Coexistence Curve ◽  
Index Of Refraction ◽  
Density Range ◽  
Temperature Range ◽  
Critical Constants

The index of refraction at 6328 Å has been measured for germane in the density range 0.15 to 0.9 g/cm3. The temperature and density ranges over which measurements are made are near the coexistence curve. The coefficient in the Lorenz–Lorentz expression, [Formula: see text], is constant to within 0.5% within experimental error for the temperature range and density range studied. The coefficient is slightly higher near the critical density. The critical density is measured to be 0.503 g/cm3. The critical temperature is measured to be 38.92 °C.

Very high purity InP layer grown by liquid‐phase epitaxy using erbium gettering

1993 ◽  
Vol 73 (1) ◽  
pp. 468-470 ◽  
Author(s):  
Meng‐Chyi Wu ◽  
Cheng‐Ming Chiu
Keyword(s):  
Liquid Phase ◽  
Liquid Phase Epitaxy ◽  
High Purity ◽  
Very High

scholarly journals Fast-Scanning Chip-Calorimetry Measurement of Crystallization Kinetics of Poly(Glycolic Acid)

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 891
Author(s):  
Yongxuan Chen ◽  
Kefeng Xie ◽  
Yucheng He ◽  
Wenbing Hu
Keyword(s):  
Crystallization Kinetics ◽  
Temperature Region ◽  
Glycolic Acid ◽  
Crystal Nucleation ◽  
Side Group ◽  
Half Time ◽  
Temperature Range ◽  
Chip Calorimetry ◽  
Kinetics Of ◽  
Fast Scanning Chip Calorimetry

We report fast-scanning chip-calorimetry measurement of isothermal crystallization kinetics of poly(glycolic acid) (PGA) in a broad temperature range. We observed that PGA crystallization could be suppressed by cooling rates beyond -100 K s−1 and, after fast cooling, by heating rates beyond 50 K s-1. In addition, the parabolic curve of crystallization half-time versus crystallization temperature shows that PGA crystallizes the fastest at 130 °C with the minimum crystallization half-time of 4.28 s. We compared our results to those of poly(L-lactic acid) (PLLA) with nearby molecular weights previously reported by Androsch et al. We found that PGA crystallizes generally more quickly than PLLA. In comparison to PLLA, PGA has a much smaller hydrogen side group than the methyl side group in PLLA; therefore, crystal nucleation is favored by the higher molecular mobility of PGA in the low temperature region as well as by the denser molecular packing of PGA in the high temperature region, and the two factors together decide the higher crystallization rates of PGA in the whole temperature range.

Diffusion In Insect Wing Muscle, The Most Active Tissue Known

1964 ◽  
Vol 41 (2) ◽  
pp. 229-256 ◽  
Author(s):  
TORKEL WEIS-FOGH
Keyword(s):  
Liquid Phase ◽  
Safety Factor ◽  
Metabolic Rates ◽  
High Concentration ◽  
Tracheal System ◽  
Insect Wing ◽  
Main Site ◽  
Normal Diffusion ◽  
Large Fibre ◽  
Very High

1. The tracheal system of insect wing muscle is so dense that between 10-1 and 10-3 of any cut area is occupied by air tubes. In most cases, air tube diffusion of O2 and CO2 through the muscle is therefore several thousand times quicker than diffusion in the liquid phase. 2. In large insects the primary tracheal supply must be strongly ventilated while diffusion is sufficient in the remaining part of the air tubes, even at the highest metabolic rates encountered in any insect. 3. The tracheoles represent the main site of exchange between the gaseous and the liquid phase while the tracheae are of little significance in this respect. The fibres cannot exceed about 20 µ in diameter unless the tracheoles indent the surface and become ‘internal’. 4. Muscular pumping of air and blood due to shortening is of little importance for the exchange of gases but of major importance for the supply with fuel for combustion. However, the large fibre diameters and the tidal nature of the pumping necessitates a very high concentration of fuel in the haemolymph. The high concentration of trehalose in insect blood is considered to be an essential adaptation to flapping flight. 5. The transport by diffusion of O2 and CO2 was followed in detail in a number of concrete examples in the gaseous as well as in the liquid phase. Within a safety factor of 2-3, the rate of transport was always found to be adequate. There is no reason to suggest other mechanisms than a simple, normal diffusion.

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