Authors:Lisardo Núñez, F. Fraga López, L. Fraga Grueiro, and J. A. Rodriguez Añón
From the peak reaction temperatures as a function of heating rate, the activation energies were obtained for a system consisting of an epoxy resin (Badgen=0) and a curing agent (isophorone diamine), using a Perkin Elmer DSC7 operated in the dynamic mode. At the same time, the Arrhenius law was used to calculate rate constants.
Authors:Mária Farkas, Ádám Illés, Balázs Petri, and Sándor Dóbé
reactions with the OH radical.
Here we report room temperature rateconstants for the reaction of OH with ELA ( 1 ). Our work is part of a comprehensive experimental and theoretical study on the kinetics and photochemistry of 2G biofuels: the first
On the basis of results of kinetic investigates of many compounds general temperature dependence of Gibbs free energy of activated
complexes created in thermal decomposition processes and the reaction rate constant were calculated.
Light emission during the dissolving of irradiated sugars (lyoluminescence, LL) allows the estimation of absorbed dose. The
use of 1-mannose as LL substance and the correlation between the concentration of paramagnetic centres and LL yield in the
presence of [Fe(CN)6]4− and CNS− anions demonstrated the possibility to measure relative rate constants of the reaction of mannose peroxy-radicals with different
substances soluble in water.
We have analyzed the dependence of the thermal electron capture rate constant on molecular parameters as dipole moment, electronic
and orientational polarizabilities. We have found that there is a linear dependence between the logarithm of the rate constant
and the electronic polarizability on the electron-accepting center.
Authors:T. Omori, R. Kimizuka, K. Yoshihara, and M. Yagi
The kinetics of reaction of indium(III)ion with EDTA (H4 edta) has been studied in aqueous acidic solutions using carrier-free111In and low concentrations of EDTA. The reaction takes place predominatly between indium(III) and H3 edta. The rate constant k3 is determined to be k3=(1.3±0.1)·105 dm3 mol–1 s–1 (25 °C).
Authors:Kwang-Pill Lee, Keung-Shik Park, Duck-Won Kang, Yasuhiro Yamada, and Shin-ichi Ohno
The mechanism of the reduction reaction of lanthanide(III) ions by hydrated electrons in polar solvents has been investigated.
The theoretical rate constants for the reaction of hydrated electrons with a number of lanthanide ions have been calculated
using the energy gap laws of the charge shift reaction(D+−A→D−A+) and compared with experimental values. With these results, we have explained the large difference of the reaction rates
of lanthanide ions with hydrated electrons, which depend upon the kind of lanthanide ion. The calculated results agree almost
quantitatively with the experimental values.
, rate constants have been evaluated for the overall radiolytic decomposition of alkali metal nitrates. This kinetic scheme is applicable in the low dose range. At higher doses, however, the radiation induced reaction, NO
may also contribute. The overall rate constants are 0.13×10–6 (LiNO3), 1.05×10–6 (NaNO3), 10.10×10–6 (KNO3), 9.50×10–6 (RbNO3) and 25.50×10–6 (CsNO3) kGy–1.
The observed rate constant ratio,k1obs/k2 obs, for the sequential iodination of L-tyrosine was determined in the concentration range 1.84·10–3 to 1·10–6 M by the use of3H- and14C-labels and product analysis by HPLC. Iodinations by chloramine-T/I– gave (k1 obs/k2 obs)· values (=the pH dependent factor) in the range 72±3 to 55±2 and molecular iodine iodinations gave values in the range 64±5 to 39±10. It is concluded that molecular iodine is the iodinating species in both cases.
Authors:G. Ch. Lainioti, J. Kapolos, A. Koliadima, and G. Karaiskakis
The major objective of the present work was to compare the kinetic study of alcoholic fermentations conducted in the presence of wheat supported biocatalysts in laboratory scale and in a scale-up system of 80 L and to compare these results with those reported in literature. The kinetic study of fermentation processes was accomplished with the technique of reversed flow gas chromatography (RFGC), which is a version of inverse gas chromatography. The wine yeast species used was Saccharomyces cerevisiae AXAZ-1, and fermentations were conducted between 20 and 2°C. At low temperatures, maximal ethanol productivity and fermentation rate were reduced. The rate constants, determined through a mathematical model obtained from RFGC, were higher in the laboratory scale comparing to the scale-up system at the temperatures of 20 and 15°C. However, with the reduction of temperature, both systems presented almost similar values proving the great fermentative ability of immobilized cells even at extremely low temperatures. Activation energies of the alcoholic fermentations in the two systems presented their higher values at the second phase (stationary) compared to those observed at the other two phases (growth and decline).