scholarly journals Hydration/Dehydration Behavior of Hydroxyethyl Cellulose Ether in Aqueous Solution

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4726
Author(s):  
Kengo Arai ◽  
Toshiyuki Shikata
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Wide Temperature Range ◽  
Water Solubility ◽  
Hydration Number ◽  
Hydroxyethyl Cellulose ◽  
Cellulose Ethers ◽  
Temperature Range ◽  
Cloud Points ◽  
Dehydration Behavior

Hydroxyethyl cellulose (HeC) maintains high water solubility over a wide temperature range even in a high temperature region where other nonionic chemically modified cellulose ethers, such as methyl cellulose (MC) and hydroxypropylmethyl cellulose (HpMC), demonstrate cloud points. In order to clarify the reason for the high solubility of HeC, the temperature dependence of the hydration number per glucopyranose unit, nH, for the HeC samples was examined by using extremely high frequency dielectric spectrum measuring techniques up to 50 GHz over a temperature range from 10 to 70 °C. HeC samples with a molar substitution number (MS) per glucopyranose unit by hydroxyethyl groups ranging from 1.3 to 3.6 were examined in this study. All HeC samples dissolve into water over the examined temperature range and did not show their cloud points. The value of nH for the HeC sample possessing the MS of 1.3 was 14 at 20 °C and decreased gently with increasing temperature and declined to 10 at 70 °C. The nH values of the HeC samples are substantially larger than the minimum critical nH value of ca. 5 necessary to be dissolved into water for cellulose ethers such as MC and HpMC, even in a high temperature range. Then, the HeC molecules possess water solubility over the wide temperature range. The temperature dependence of nH for the HeC samples and triethyleneglycol, which is a model compound for substitution groups of HeC, is gentle and they are similar to each other. This observation strongly suggests that the hydration/dehydration behavior of the HeC samples was essentially controlled by that of their substitution groups.

Elastic Constants in C-plane of Single Crystal Bi 2Sr 2Ca Cu 208 between 80 K and 260 K

1990 ◽  
Vol 193 ◽  
Author(s):  
Jin Wu ◽  
Yening Wang ◽  
Yifeng Yan ◽  
Zhongxian Zhao
Keyword(s):  
Shear Modulus ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Elastic Constants ◽  
Wide Temperature Range ◽  
Sound Propagation ◽  
Anisotropic Elasticity ◽  
Ultrasonic Velocities ◽  
Temperature Range

ABSTRACTThe temperature dependence of the in-plane C11 C22. C12 and C66 modes between 80 and 260 K of superconducting crystals of Bi2Sr2Ca1Cu208 have been obtained via the measurements of ultrasonic-velocities. The anisotropic elasticity in the a-b plane of single crystal Bi2 Sr2Ca1Cu2O8 is manifest. The shear modulus of sound propagation along the [110] with the polarization has been also calculated and shows an overall trend of softening over a wide temperature range above Tc. The shear modulus C6 6 shows three obvious softening minima around 240–250 K, 150 K and 100 K.

CMOS Circuits on Silicon Carbide for High Temperature Operation

2014 ◽  
Vol 1693 ◽  
Author(s):  
David T. Clark ◽  
Robin F. Thompson ◽  
Aled E. Murphy ◽  
David A. Smith ◽  
Ewan P. Ramsay ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Wide Temperature Range ◽  
Integrated Circuit ◽  
Elevated Temperatures ◽  
Logic Circuits ◽  
Digital Logic ◽  
Cmos Integrated Circuit ◽  
Temperature Range ◽  
Simple Logic

ABSTRACTWe present the characteristics of a high temperature CMOS integrated circuit process based on 4H silicon carbide designed to operate at temperatures beyond 300°C. N-channel and P-channel transistor characteristics at room and elevated temperatures are presented. Both channel types show the expected low values of field effect mobility well known in SiC MOSFETS. However the performance achieved is easily capable of exploitation in CMOS digital logic circuits and certain analogue circuits, over a wide temperature range.Data is also presented for the performance of digital logic demonstrator circuits, in particular a 4 to 1 analogue multiplexer and a configurable timer operating over a wide temperature range. Devices are packaged in high temperature ceramic dual in line (DIL) packages, which are capable of greater than 300°C operation. A high temperature “micro-oven” system has been designed and built to enable testing and stressing of units assembled in these package types. This system heats a group of devices together to temperatures of up to 300°C while keeping the electrical connections at much lower temperatures. In addition, long term reliability data for some structures such as contact chains to n-type and p-type SiC and simple logic circuits is summarized.

The thermodynamics of the vaporization of liquid indium(I) bromide by modified entrainment

1991 ◽  
Vol 69 (9) ◽  
pp. 1394-1397 ◽  
Author(s):  
Peter J. Gardner ◽  
Steve R. Preston
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Key Words ◽  
Vapour Pressure ◽  
Carrier Gas ◽  
Temperature Range ◽  
Liquid Indium

The transport of gaseous In(I)Br in an argon carrier gas was studied in the temperature range 680 to 935 K by the modified entrainment method. Combination of the entrainment results with a literature equation for the total vapour pressure above the liquid gave the following expressions for the temperature dependence of the vapour pressures of the monomer (In2Br2) and dimer (In2Br2) respectively: [Formula: see text] ln T − 0.001164 ± 0.00021)T, (680 −950 K) and [Formula: see text] (680–810 K); p0 = 105 Pa. The dimer concentration is ca. 14% at 680 K and decreases to ca. 4% at 810 K. Key words: high temperature thermodynamics, indium(I) bromide, vaporization thermodynamics.

scholarly journals On the Temperature Dependence of Vaporization Enthalpy and its Correlation with Surface Tension.

2021 ◽  
Author(s):  
Amin Alibakhshi ◽  
Bernd Hartke
Keyword(s):  
Surface Tension ◽  
Critical Temperature ◽  
Melting Point ◽  
Temperature Dependence ◽  
Wide Temperature Range ◽  
Thermophysical Properties ◽  
Vaporization Enthalpy ◽  
Temperature Range

Temperature dependence of vaporization enthalpy is one of the most important thermophysical properties of compounds. In the present study, we theoretically developed relationships applicable to evaluation of vaporization enthalpy of compounds from diverse chemical families for a wide temperature range from melting point to the critical temperature. One outcome of the proposed approach is a relationship describing the correlation between the surface tension and vaporization enthalpy which outperforms the extensively applied Kabo method proposed for the same purpose.<br>

scholarly journals High temperature, Smart Power Module for aircraft actuators

2013 ◽  
Vol 2013 (HITEN) ◽  
pp. 000069-000074
Author(s):  
Khalil El Falahi ◽  
Stanislas Hascoët ◽  
Cyril Buttay ◽  
Pascal Bevilacqua ◽  
Luong-Viet Phung ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Wide Temperature Range ◽  
Power Module ◽  
Smart Power ◽  
Temperature Range ◽  
Electric Aircraft ◽  
Gate Driver ◽  
Proper Operation ◽  
More Electric Aircraft

More electric aircraft require converters that can operate over a wide temperature range (−55 to more than 200°C). Silicon carbide JFETs can satisfy these requirements, but there is a need for suitable peripheral components (gate drivers, passives. . . ). In this paper, we present a “smart power module” based on SiC JFETs and dedicated integrated gate driver circuits. The design is detailed, and some electrical results are given, showing proper operation of the module up to 200°C.

Prediction of Fracture Toughness Temperature Dependence Over a Wide Temperature Range Using Simplified and Direct Scaling Method

2018 ◽  
Author(s):  
Takashi Inoue ◽  
Toshiyuki Meshii
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Wide Temperature Range ◽  
Fracture Load ◽  
Specimen Thickness ◽  
Temperature Range ◽  
Direct Scaling ◽  
Wide Range ◽  
Mc Method

The fracture toughness KJc of the material in the ductile to brittle transition temperature (DBTT) range exhibits both test specimen thickness (TST) dependence and temperature dependence. Attention has been paid to the master curve (MC) method, which provides an engineering approach to address these two issues. Although MC is intended to be applied to arbitrary ferritic material whose yield stress is within the range of 275 to 825 MPa, the KJc value must be obtained to determine the material dependent reference temperature T0. The applicable range of MC method is restricted to T0 ± 50 °C. Previous studies indicate that additional pre-tests to obtain T0 are necessary; thus, there might be some unwritten requirement to the test temperature for the KJc temperature dependence prediction in MC method to work effectively. If testing must be conducted for the material of interest at some restricted temperature, a more flexible KJc temperature dependence prediction can possibly be obtained for a wide temperature range in the DBTT range, if the simplified and direct scaling (SDS) method, which predicts fracture “load” from yield stress temperature dependence proposed previously is applied. In this study, the SDS method was applied to two different steels: Cr-Mo steel JIS SCM440 and 0.55% carbon steel JIS S55C. Both tensile and fracture toughness tests were performed over a wide range of temperatures, specifically, −166 to 100 °C for SCM440 and −166 to 20 °C for S55C. The SDS method (i.e., fracture load is proportional to 1/(yield stress)) was initially validated for the specimens in the DBTT range. Finally, a simplified method was proposed and initially validated to predict the KJc temperature dependence, by applying the SDS using the EPRI plastic J functional form.

A Robust SOI Gain-Boosted Operational Amplifier Targeting High Temperature Precision Applications up to 300°C

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000238-000242
Author(s):  
Alexander Schmidt ◽  
Abdel Moneim Marzouk ◽  
Holger Kappert ◽  
Rainer Kokozinski
Keyword(s):  
High Temperature ◽  
Circuit Design ◽  
Robust Design ◽  
Wide Temperature Range ◽  
Operational Amplifier ◽  
Operating Temperature ◽  
High Gain ◽  
Temperature Range ◽  
Op Amp ◽  
Operating Temperature Range

Data acquisition and signal processing at elevated temperatures are facing various problems due to a wide temperature range operation, affecting the accuracy of the circuits' references and elementary building blocks. As the most commonly used analog building block, the operational amplifier (op-amp) with its various limitations has to be enhanced for wide temperature range operation. Thereby major effort is put into maximizing signal gain and simultaneously reaching high gain-bandwidth also for high temperatures. Future robust design approaches have to consider a growing operating temperature range and increasing device parameter mismatch due to the downsizing of integrated circuits. Addressing one of the major problems in circuit design for the next decades, compensating these effects through new design approaches will have a lasting impact on circuit design. In this paper we present a high gain operational amplifier with a folded-cascode and gain-boosted input stage, fabricated in a 1.0 μm SOI CMOS process. The operational amplifier was designed for an operating temperature range of −40…300°C. Major effort was put into a robust design approach with reduced sensitivity to temperature variations, targeting high precision applications in a high temperature environment. With a supply voltage of 5 V, the maximum simulated current consumption of the op-amp is 210 μA which leads to overall maximum power consumption of 1.05 mW. The open loop DC gain of the amplifier is expected to reach a minimum of 108 dB and a unity-gain-frequency of 1.02 MHz at a temperature of 300°C. For all temperatures the phase margin varies from 55…70 degrees for a 3 pF load.

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