Thermal rearrangement of 7,7-dichloro-[a,c]-dibenzo-[4,1,0]-bicycloheptane (1) to 5,6-dichloro-5Hdibenzo-[a,c]-cycloheptene (2) was studied in the solid phase and in solvents with different polarities. Thefirst-order constants at various temperatures for the rearrangement process were evaluated from theabsorption time data. The activation parameters for this rearrangement were obtained from the...

The majority of recent temperature studies which have been made on enzyme systems indicate that their rate, like that of chemical reactions, increases exponentially with the absolute temperature in accordance with the Arrhenius equation. With enzymes, however, this temperature activation ceases above the inactivation temperature of the enzyme. For a specific enzyme system the energy of activati...

Heat-inactivation studies were carried out on the two primary erythrocyte carbonic anhydrase isoenzymes, CA I and CA II, and the secondary isoenzyme of CA I, CA I (+1). In addition, two genetic variants of human isoenzyme CA I, CA Id Michigan (100 Thr-->Lys) and CA If London (102 Glu-->Lys), and one variant of isoenzyme CA II, CA IIh (251 Asn-->Asp), were similarly analysed. The first-order rat...

Circadian clocks--ubiquitous in life forms ranging from bacteria to multicellular organisms--often exhibit intrinsic temperature compensation; the period of circadian oscillators is maintained constant over a range of physiological temperatures, despite the expected Arrhenius form for the reaction coefficient. Observations have shown that the amplitude of the oscillation depends on the temperat...

The rate for cross slip of screw dislocations during annihilation of screw dipoles in copper is determined by molecular dynamics simulations. The temperature dependence of the rate is seen to obey an Arrhenius behavior in the investigated temperature range: 225-375 K. The activation energy and the effective attempt frequency can therefore be extracted from the simulations. The transition state ...

The kinetics of the refolding of the enzyme, human carbonic anhydrase II (HCA II), at different temperatures, together with the Escherichia coli chaperonin GroEL, has been studied. The Arrhenius plots for the spontaneous, GroEL-assisted, and GroEL/ES-assisted refolding of HCA II show that the apparent activation energy (E(a)) is lower in the presence of the chaperonin GroEL alone than for the s...

We present simulation results on the equilibrium relaxation of Brownian planar rotors based on a uniformly frustrated XY model on a square lattice. The rotational relaxation exhibits typical dynamic features of fragile supercooled liquids including the two-step relaxation. We observe a dynamic cross-over from high temperature regime with Arrhenius behavior to low temperaure regime with temeratu...

We present simulation results on the equilibrium relaxation of Brownian planar rotors based on a uniformly frustrated XY model on a square lattice. The rotational relaxation exhibits typical dynamic features of fragile supercooled liquids including the two-step relaxation. We observe a dynamic crossover from the high-temperature regime with Arrhenius behavior to the low-temperature regime with ...

The recombination of Frenkel pairs resulting from low energy recoils in 3C-SiC has been investigated using first principles and Nudged Elastic Band calculations. Several recombination mechanisms have been obtained, involving direct interstitial migration, atoms exchange, or concerted displacements, with activation energies ranging from 0.65 eV to 1.84 eV. These results are in agreement with exp...

This study aims to propose a kinetics-based model of fatigue crack growth rate coupling with temperature, strain level and damage degree for bituminous materials. The length is calculated by an energy-based mechanistic (EBM) approach, kinetic parameters characterizing the are determined based on Arrhenius equation. Results show that logarithm linear inverse absolute cracking activation energy i...