scholarly journals Temperature Dependence of Viscosity and Density of cis-1,4/trans-1,3-Dimethylcyclohexane and Several other Commonly Used Organic Solvents

2003 ◽  
Vol 217 (6) ◽  
pp. 707-722 ◽  
Author(s):  
A. A. Ruth ◽  
H. Lesche ◽  
B. Nickel
Keyword(s):  
Low Temperature ◽  
Temperature Dependence ◽  
Organic Solvents ◽  
Temperature Regime ◽  
Dynamic Viscosity ◽  
Temperature Range ◽  
Viscosity Measurements ◽  
Glass Forming ◽  
Temperature Ranges

AbstractThe dynamic viscosity (η) of the glass-forming 50:50 mixture of cis-1,4/trans-1,3-dimethylcyclohexane (ct-DMCH) was measured from 293 K down to ≈ 126 K where η ~ 1.2 × 106 mPas. The viscosity measurements of several other commonly used solvents cover the range from 293 K down to ≈ 148 K (η ~ 1.4 × 104 mPas) for 1-propanol (1-Prop), to ≈118 K (η ~ 2.5 × 102 mPas) for 2-methylpentane (2-MP), to ≈ 167 K (η ~ 10.0 mPas) for isooctane (Isooct), to ≈ 183 K (η ~ 2.8 mPas) for cyclopentane (CP) and down to ≈ 98 K (η ~ 4.6 × 102 mPas) for the 30:70 mixture of cyclopentane/isopentane (CP/IP). The density (ρ) of all solvents was measured correspondingly over appropriate temperature ranges. For the solvents studied here, the temperature dependence of the viscosity can be represented by a single Arrhenius term down to ~180 K. Over a wider temperature range down to ~118K the sum of two Arrhenius terms is required, and in the low temperature regime a Vogel–Tammann–Fulcher expression is necessary to adequately describe the temperature dependence of the dynamic viscosity.

Searching accurate predicted viscosities near the melting point in a non-strong glass-forming liquid

2020 ◽  
Vol 34 (26) ◽  
pp. 2050230
Author(s):  
Qian Gao ◽  
Zengyun Jian ◽  
Man Zhu ◽  
Yan Chen ◽  
Bo Dang ◽  
...  
Keyword(s):  
Melting Point ◽  
Measured Data ◽  
Viscosity Data ◽  
Temperature Range ◽  
Glass Forming ◽  
Temperature Ranges ◽  
Measured Viscosity

The accurate predicted viscosities near the melting point [Formula: see text] have been searched. In order to find the temperature ranges, where the measured viscosity data applied to obtain the accurate fitting viscosity data and the accurate fitting expressions near [Formula: see text] lie, the measured data in 15 different temperature ranges (a)–(o) are applied to obtain the fitting viscosity data and the fitting expressions by the Vogel–Fulcher–Tammann (VFT) relation. The accuracy of the fitting viscosity near [Formula: see text] will varies when the measured data in different temperature ranges are applied to obtain the fitting viscosity data by VFT relation. It is found that the accurate fitting viscosity data with the coefficients of determination [Formula: see text] in temperature range 397.3–583.6 K (0.84–1.24[Formula: see text]) near [Formula: see text] can be acquired using the measured data in temperature ranges (g)–(h) and (k) by the VFT relation. In other words, we found the temperature ranges (namely, temperature ranges (g)–(h) and (k)), in which the measured viscosity data applied to obtain the accurate fitting viscosity data and the accurate fitting expressions near [Formula: see text] exist.

scholarly journals Avalanche Diodes with Low Temperature Dependence in 4H-SiC Suitable for Parallel Protection

2011 ◽  
Vol 679-680 ◽  
pp. 567-570 ◽  
Author(s):  
Duy Minh Nguyen ◽  
Gontran Pâques ◽  
Nicolas Dheilly ◽  
Christophe Raynaud ◽  
Dominique Tournier ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Dependence ◽  
Impact Ionization ◽  
Temperature Range ◽  
Avalanche Diodes ◽  
Ionization Coefficients

Avalanche diodes have been fabricated on 4H-SiC substrate. These diodes show an abrupt avalanche voltage of about 59 V which corresponds to the calculated theoretical one using our previously determined impact ionization coefficients. This avalanche voltage increases by as small as 3.7 mV/K over the investigated temperature range (150K-420K).

Two temperature regimes of triplet transfer in the dissociation of the correlated triplet pair after singlet fission

2019 ◽  
Vol 97 (6) ◽  
pp. 465-473 ◽  
Author(s):  
Tia S. Lee ◽  
YunHui L. Lin ◽  
Hwon Kim ◽  
Barry P. Rand ◽  
Gregory D. Scholes
Keyword(s):  
Low Temperature ◽  
Temperature Dependence ◽  
Temperature Regime ◽  
Transient Absorption Spectroscopy ◽  
Type Model ◽  
Singlet Fission ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Pair Separation ◽  
Triplet Pair

The ability to undergo spin-allowed exciton multiplication makes singlet fission materials promising for photovoltaic applications. Here, we examine the separation of correlated triplet pairs, 1(T…T), in polycrystalline pentacene films via temperature-dependent transient absorption spectroscopy. Single wavelength analysis reveals a profound delay in 1(T…T) dynamics. Moreover, the dynamics of 1(T…T) exhibit temperature dependence, whereas other features show no discernable temperature dependence. Previous literatures have suggested that correlated triplet separation is mediated by a thermally activated hopping process. Surprisingly, we found that the time constants governing triplet pair separation display two distinct temperature-dependent regimes of triplet transport. The high temperature regime follows a thermally activated hopping mechanism. The experimentally derived reorganization energy and electronic coupling is verified by density matrix renormalization group quantum chemical calculations. In addition, we evaluated the low temperature regime and show that the trend can be modelled by a Miller–Abrahams-type model that incorporates the effects of energetic disorder. We conclude that the correlated triplet pair separation is mediated by thermally activated hopping or a disorder driven Miller–Abrahams-type mechanism at high and low temperature, respectively. We observe that crossover between two regimes occurs ∼226 K. We find the time constant for triplet–triplet energy transfer to be 1.8 ps at ambient temperature and 21 ps at 77 K.

Diapause in the Eggs of Austroicetes cruciata, Sauss. (Acrididae) with particular Reference to the Influence of Temperature on the Elimination of Diapause

1943 ◽  
Vol 34 (1) ◽  
pp. 1-17 ◽  
Author(s):  
H. G. Andrewartha
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Influence Of Temperature ◽  
Temperature Range ◽  
Abnormal Growth ◽  
Inhibition Of Growth ◽  
Stage Of Development ◽  
Influence Of Temperature On ◽  
Temperature Ranges ◽  
The One

Diapause should not be confused with simple inhibition of growth due to cold.The embryo of the grasshopper, Austroicetes cruciata, enters a state of diapause a few days after the egg is laid. The diapause is obligate like that found in the eggs of Circotettix, rather than facultative like that found in the larvae of Platyedra. These types of diapause should be regarded as two extremes of the one phenomenon rather than two distinct phenomena.Diapause was eliminated when the egg was exposed to adequate low temperature for an adequate period when the embryo was at a suitable stage of development. If the period at low temperature was inadequate, or if the embryo was not at a suitable stage of development when the exposure to low temperature occurred, diapause was only partially eliminated. In such cases, the exposure to low temperature resulted in an abnormal growth by the embryo when the egg was returned to a favourable high temperature, but development was not completed.The influence of low temperature on the elimination of diapause was due chiefly to changes which occurred in the yolk during exposure to low temperature. Thus yolk which had been modified in this way became suitable for the nourishment of the embryo, and it no longer obstructed katatrepsis. This explanation of the nature of the obligate diapause in the eggs of Austroicetes brings this phenomenon into line with the facultative diapause in the larvae of Platyedra, which has been shown to be associated with the nourishment of the larva.Diapause was eliminated most rapidly at temperatures between 6°C. and 13°C. The embryo grew most rapidly at about 30°C. ; below 13°C. growth practically ceased. The absence of overlapping of the temperature ranges for these two processes may explain the presence of diapause in Austroicetes. The occurrence of a less pronounced diapause in the eggs of Melanoplus may be due to a partial overlapping of the temperature range for the two processes. Similarly the absence of diapause in the eggs of Locusta may be explained on the assumption that in this species the two processes proceed over the same temperature range.

scholarly journals The low-temperature mechanical properties of the Fe40Mn40Co10Cr10 high-entropy alloy, the ductility of which is induced by twinning

2020 ◽  
Keyword(s):  
Plastic Deformation ◽  
Low Temperature ◽  
Yield Strength ◽  
Temperature Dependence ◽  
Low Temperatures ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Temperature Range ◽  
Deformed State ◽  
Strength And Ductility

In this work, we studied the low-temperature plasticity, elastic and dissipative characteristics, as well as the microstructural evolution of the Fe40Mn40Co10Cr10 high-entropy alloy in a wide temperature range of 300 - 0.5 K. The temperature dependences of yield strength, strain hardening, strength and ductility, as well as acoustic absorption and dynamic Young's modulus are obtained. It was found that the structure of Fe40Mn40Co10Cr10 alloy in the initial state is single-phase with fcc lattice, and in the deformed state at low temperatures it becomes two-phase due to the deformation-induced phase transition. In addition, EBSD analysis of the alloy structure revealed a change in grain morphology and the appearance of twin dislocations after plastic deformation at all investigatedtemperatures. Acoustic studies showed that the transition from the initial to the deformed state changes the character of the temperature dependence of the dynamic Young's modulus from almost linear to exponential, and reduces the absolute values. The Fe40Mn40Co10Cr10 alloy has excellent strength and ductility at a high strain hardening rate, which is explained by the significant contribution of the twinning process. With a decrease in temperature from 300 to 4.2 K, a strong temperature dependence of the yield strength is observed, which indicates the thermal activation of the nature of the plastic deformation of the alloys in this temperature range. In the temperature range of 0.5-4.2 K, an anomaly of the yield strength was observed, namely a decrease in the value of the yield strength with decreasing temperature from 4.2 K to 0.5 K. The anomalous dependence of the yield strength is due to a change in the mechanism of overcoming local barriers from thermoactivated to inertial one, when part of the local obstacles is overcome by dislocations without activation. This leads to a decrease in yield strength with decreasing temperature. At a temperature of 4.2 K and below, the smooth nature of the plastic deformation changes from smooth to serrated. The jumps begin immediately after the yield strength and gradually increase from 40 MPa to ~ 160 MPa. The results obtained are important for practical applications of high-entropy alloys at low temperatures.

scholarly journals Низкотемпературные магнитные свойства аморфного ферромагнитного микропровода из сплава Fe-Si-B в стеклянной оболочке и без нее

2018 ◽  
Vol 60 (6) ◽  
pp. 1147
Author(s):  
И.А. Барабан ◽  
А.В. Емельянов ◽  
П.Н. Медведская ◽  
В.В. Родионова
Keyword(s):  
Magnetic Properties ◽  
Low Temperature ◽  
Magnetic Fields ◽  
Temperature Dependence ◽  
Magnetic Moment ◽  
Room Temperature ◽  
High Magnetic Fields ◽  
Glass Coating ◽  
Temperature Range ◽  
Taylor Method

AbstractThis work presents results of investigations of low temperature magnetic properties of microwires, fabricated by the Ulitovsky–Taylor method from Fe–Si–B alloy. Influence of the glass coating presence on the magnetostatic properties was shown at room temperature and at 2 K. Conclusions about the peculiarities of temperature dependence of the magnetic moment, measured in low and high magnetic fields (10 Oe–5 kOe) in the temperature range from 2 to 300 K for a sample with partially reduced fabricated processinduced stress by removing the glass, were made.

scholarly journals Temperature Dependence of Elastic Moduli of Several Steels at Low Temperature Range

1979 ◽  
Vol 28 (312) ◽  
pp. 852-856 ◽  
Author(s):  
Yoichiro TAKEUCHI ◽  
Naotake NODA ◽  
Shigeru KOMORI ◽  
Takuo YAMATO
Keyword(s):  
Low Temperature ◽  
Temperature Dependence ◽  
Elastic Moduli ◽  
Temperature Range
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