Modeling the flow curves of materials at elevated temperatures is the first step in mathematical simulation of the hot deformation processes of them. In this work a comparative study was provided to examine the capability of three different constitutive equations in modeling the hot deformation flow curves of AZ91 magnesium alloy. For this, the Arrhenius equation with strain dependent constants...

In the present research, synthesis of butyl oleate ester from oleic acid and butanol using loofa-immobilized Rhizopus oryzae as a whole cell biocatalyst (LIC) was studied in which hexane was used as the hydrophobic solvent. Decrease of mass transfer limitations as result of the interface formation between the two immiscible substrates, positively affected on the reaction progress (87% as the es...

Single-molecule magnets (SMMs) are molecules that, below a certain temperature (TB), function as individual nanoscale magnetic particles, exhibiting magnetization hysteresis loops. As such, they represent an alternative and molecular (bottom-up) route to nanomagnetism, complementing the top-down approach to traditional magnetic nanomaterials. SMMs also exhibit fascinating quantum behavior such ...

guaiacol peroxidases (gp) are haem-containing enzymes participating in many physiological processes in plants. the expression pattern of these enzymes is organ-specific and developmentally regulated. methods: the presence of gp activity in extract samples, prepared from crocus sativus l. corms that were either dormant or rooting for 3, 6 and 10 days, was investigated. results: kinetic studies r...

The purpose of this article is to trace the origins of the Arrhenius equation and, in the light of the extensive data on the temperature dependence of reaction rates, assembled in just over a century of experimental endeavor, to assess in what ways its status has changed over the period since it was first proposed. The systematic study of the kinetics of chemical reactions commenced ( I ) mid-w...

The influence of low temperature on soybean (Glycine max [L.] Merr. cv. Wells) energy transduction via mitochondrial respiration and dehydrogenases was investigated in this study during imbibition and germination. Mitochondria were isolated from embryonic axes of seeds treated at 10 and 23 C (control) by submergence in H(2)O for 6 hours and maintenance for an additional 42 hours in a moist envi...

The effect of temperature (0-22 degrees C) on the kinetics of Na channel conductance was determined in voltage-clamped rabbit and frog skeletal muscle fibers using the triple-Vaseline-gap technique. The Hodgkin-Huxley model was used to extract kinetic parameters; the time course of the conductance change during step depolarization followed m3h kinetics. Arrhenius plots of activation time consta...

Accelerated stability tests are indicated to assess, within a short time, the degree of chemical degradation that may affect an active substance, either alone or in a formula, under normal storage conditions. This method is based on increased stress conditions to accelerate the rate of chemical degradation. Based on the equation of the straight line obtained as a function of the reaction order ...

Molecular dynamics simulations have been used extensively to model the folding and unfolding of proteins. The rates of folding and unfolding should follow the Arrhenius equation over a limited range of temperatures. This study shows that molecular dynamic simulations of the unfolding of crambin between 500K and 560K do follow the Arrhenius equation. They also show that while there is a large am...