Origin of a Large Temperature Dependence of Regioselectivity Observed for [2 + 2] Photocycloaddition (Paternò-Büchi Reaction) of 1,3-Dimethylthymine with Benzophenone and Its Derivatives:  Conformational Property of the Intermediary Triplet 1,4-Diradicals

2005 ◽  
Vol 70 (7) ◽  
pp. 2522-2527 ◽  
Author(s):  
Xiao-Ming Hei ◽  
Qin-Hua Song ◽  
Xi-Bo Li ◽  
Wen-Jian Tang ◽  
Hong-Bo Wang ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Large Temperature ◽  
Conformational Property

Unprecedented Large Temperature Dependence of Silver(I)–Silver(I) Distances in Some N-Heterocyclic Carbene Silver(I) Complex Salts

2013 ◽  
Vol 32 (10) ◽  
pp. 2876-2884 ◽  
Author(s):  
Margit Kriechbaum ◽  
Johanna Hölbling ◽  
Hans-Georg Stammler ◽  
Manuela List ◽  
Raphael J. F. Berger ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Large Temperature ◽  
Complex Salts

Iron-based superelastic alloys with near-constant critical stress temperature dependence

Science ◽  
2020 ◽  
Vol 369 (6505) ◽  
pp. 855-858 ◽  
Author(s):  
Ji Xia ◽  
Yuki Noguchi ◽  
Xiao Xu ◽  
Takumi Odaira ◽  
Yuta Kimura ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Temperature Dependence ◽  
Critical Stress ◽  
Outer Space ◽  
Alloy System ◽  
Large Temperature ◽  
Superelastic Behavior ◽  
Iron Based ◽  
Metal Shape

Shape memory alloys recover their original shape after deformation, making them useful for a variety of specialized applications. Superelastic behavior begins at the critical stress, which tends to increase with increasing temperature for metal shape memory alloys. Temperature dependence is a common feature that often restricts the use of metal shape memory alloys in applications. We discovered an iron-based superelastic alloy system in which the critical stress can be optimized. Our Fe-Mn-Al-Cr-Ni alloys have a controllable temperature dependence that goes from positive to negative, depending on the chromium content. This phenomenon includes a temperature-invariant stress dependence. This behavior is highly desirable for a range of outer space–based and other applications that involve large temperature fluctuations.

scholarly journals Temperature-Dependence of Rubber Hyperelasticity Based on the Eight-Chain Model

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 932 ◽  
Author(s):  
Xintao Fu ◽  
Zepeng Wang ◽  
Lianxiang Ma ◽  
Zhaoxuan Zou ◽  
Qingling Zhang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Rubber ◽  
Temperature Dependence ◽  
Large Temperature ◽  
Chain Model ◽  
Element Analysis ◽  
Filled Rubber ◽  
Different Temperatures

Rubber-based materials are widely used in a variety of industrial applications. In these applications, rubber components withstand various loading conditions over a range of temperatures. It is of great significance to study the mechanical behavior of vulcanized rubber at different temperatures, especially in a range of high temperatures. The temperature dependence of the constitutive behavior of filled rubber is important for the performance of the rubber. However, only a few constitutive models have been reported that investigate the stress–temperature relationship. In this paper, based on an analysis of experimental data, the effects of temperature on the hyperelastic behaviors of both natural rubber and filled rubber, with different mass fractions of carbon black, were studied. The regulation of stress and strain of natural rubber and filled rubber with temperature was revealed. In addition, an eight-chain model that can reasonably characterize the experimental data at different temperatures was proved. An explicit temperature-dependent constitutive model was developed based on the Arruda-Boyce model to describe the stress–strain response of filled rubber in a relatively large temperature range. Meanwhile, it was proved that the model can predict the effect of temperature on the hyperelastic behavior of filled rubber. Finally, the improved Arruda-Boyce model was used to obtain the material parameters and was then successfully applied to finite element analysis (FEA), which showed that the model has high application value. In addition, the model had a simple form and could be conveniently applied in related performance test of actual production or finite element analysis.

Optimized Nonreciprocal Rib Waveguides for Integrated Magneto-Optic Isolators

1998 ◽  
Vol 517 ◽  
Author(s):  
M. Wallenhorst ◽  
V. Backherms ◽  
A. Josef ◽  
N. Bahlmann ◽  
M. Lohmeyer ◽  
...  
Keyword(s):  
Phase Shift ◽  
Temperature Dependence ◽  
Double Layer ◽  
Faraday Rotation ◽  
Single Layer ◽  
Large Temperature ◽  
Gadolinium Gallium Garnet ◽  
Rare Earth Ion ◽  
Garnet Films ◽  
Rib Waveguides

AbstractGarnet films of composition (Lu,Bi)3(Fe,Ga,Al)5O12 and (Tm,Bi)3(Fe,Ga)5O12 are grown by liquid-phase epitaxy on [111]-oriented substrates of gadolinium gallium garnet. Ferrimagnetic films with positive or negative Faraday-rotation as well as paramagnetic films with negligible Faraday-rotation are produced by variations of the rare earth ion substitutions. The temperature dependence of Faraday-rotation is fitted with a molecular field model. Optical rib waveguides in single and double layer garnet films with different Faraday-rotations are realized. The nonreciprocal phase shift of the TM0-Mode is studied both theoretically and experimentally at a wavelength of 1.3 μm. Results show that the maximum nonreciprocal effect at room temperature of double layer films with opposite Faraday-rotation is 1.6 times as large as that of comparable single layer waveguides. But, because of the large temperature dependence of the Faraday-rotation of the positive rotating films, these waveguides show a large temperature dependence of the nonreciprocal phase shift. This problem can be avoided if the positive rotating layer is replaced by a paramagnetic layer. Agreement between calculations and measurements is excellent.

OBSERVATION OF THE NMR SPIN–SPIN RELAXATION OF SOME POLYBUTADIENE-C7D8 SOLUTIONS

2006 ◽  
Vol 20 (28) ◽  
pp. 1795-1801
Author(s):  
M. TODICA
Keyword(s):  
Temperature Dependence ◽  
Spin Relaxation ◽  
Experimental Parameter ◽  
Nmr Relaxation ◽  
Transverse Magnetization ◽  
Large Temperature ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Polymeric Chains ◽  
Relaxation Curves

The NMR relaxation of the transverse magnetization of the protons attached to the polymeric chains was observed for the molten polybutadiene and for some polybutadiene–toluene solutions in a large temperature domain. The superposition properties of the relaxation curves, the linear temperature dependence of the experimental parameter t0.6(T) and the observation of the pseudo-solid echoes were correlated to the existence of the temporary junctions between the polymeric chains.

Temperature dependence of transport properties of InN films

2005 ◽  
Vol 892 ◽  
Author(s):  
J.S. Thakur ◽  
R. Naik ◽  
Vaman M Naik ◽  
D. Haddad ◽  
G.W. Auner ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Temperature Dependence ◽  
Electron Scattering ◽  
Carrier Density ◽  
Molecular Beam ◽  
Plasma Source ◽  
Large Temperature ◽  
Independent Mobility ◽  
Donor Acceptor ◽  
High Carrier

AbstractThe temperature dependence of Hall mobility, µ, and carrier density, Ne, for thin InN films grown by Molecular Beam Epitaxy and Plasma Source Molecular Beam Epitaxy have been investigated. For temperature up to 300 K, a large temperature-independent Ne is observed in films grown by the above two techniques. However, for higher temperatures, carrier density (Ne) increases with temperature. The characteristic behavior of the mobility for the films with low carrier density is different from that of the high carrier density film, particularly at low temperatures. The low carrier density film shows a peak ∼250 K in mobility as a function of temperature which is contrast to the temperature independent mobility observed for the high density film for T < 300 K. We have investigated theoretically the effect of concentration of donor, acceptor, and threading dislocations on the carrier mobility in these films. Various electron-scattering mechanisms for the mobility in these films have been discussed.

Carbon-13 kinetic isotope effects. IV. The effect of temperature on k12/k13 for benzyl halides in bimolecular reactions

1968 ◽  
Vol 46 (11) ◽  
pp. 1825-1829 ◽  
Author(s):  
Jan Bron ◽  
J. B. Stothers
Keyword(s):  
Temperature Dependence ◽  
Temperature Effect ◽  
Isotope Effects ◽  
Benzyl Bromide ◽  
Kinetic Isotope Effects ◽  
Effect Of Temperature ◽  
Large Temperature ◽  
Bimolecular Reactions ◽  
Kinetic Isotope ◽  
Benzyl Halides

The temperature dependence of the 13C kinetic isotope of the α-carbon in benzyl bromide (1) and in 1-bromo-1-phenylethane (2) has been measured for reaction with alkoxide ion. For these bimolecular displacements, a relatively large temperature effect was found, comparable to that reported for other SN2 processes. A reexamination of the reaction of 2 with EtO− has shown an earlier value for k12/k13 to be in error.

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