Determination of activation parameters for dislocation formation from a surface in fcc metals by atomistic simulations

2008 ◽  
Vol 78 (6) ◽  
Author(s):  
P. Hirel ◽  
J. Godet ◽  
S. Brochard ◽  
L. Pizzagalli ◽  
P. Beauchamp
Keyword(s):  
Activation Parameters ◽  
Atomistic Simulations ◽  
Fcc Metals ◽  
Dislocation Formation

Kinetics and mechanism of redox reactions of U(III) ions with monochloroacetic and dichloroacetic acids

1979 ◽  
Vol 44 (2) ◽  
pp. 401-405 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Ľudovít Treindl
Keyword(s):  
Redox Reactions ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Outer Sphere ◽  
Alcohol Concentration ◽  
Kinetics And Mechanism ◽  
Solvent Structure ◽  
Influence Of Ph ◽  
Sphere Mechanism

The kinetics and mechanism of the redox reactions of U3+ ions with mono- and dichloroacetic acids were studied. The influence of pH was observed mainly in the second case and led to the determination of the rate constants and activation parameters corresponding to two parallel steps, namely oxidation of U3+ with CHCl2COO- ions and oxidation of U3+ with CHCl2.COOH molecules. The influence of binary mixtures of water with methanol, ethanol, isopropanol, or tert-butenol on the reaction rate was followed. Increasing alcohol concentration influences the rate constant not only through changing dielectric constant and solvation of the reactants but also through a change of the solvent structure which plays a role in reactions with an outer sphere mechanism of the electron transfer.

Steroids and steroidases. IX. Activation parameters and the mechanism of base- and enzyme-catalyzed isomerizations of androst-5-ene-3,17-dione. The nature of the active center of the Δ5 → Δ4-3-ketosteroid isomerase of Pseudomonas testosteroni

1969 ◽  
Vol 47 (23) ◽  
pp. 4459-4466 ◽  
Author(s):  
J. Bryan Jones ◽  
Donald C. Wigfield
Keyword(s):  
Amino Acids ◽  
Active Center ◽  
Activation Parameters ◽  
Circumstantial Evidence ◽  
Kcal Mole ◽  
Acid Base ◽  
Ketosteroid Isomerase ◽  
Enzyme Action ◽  
Enthalpy Of Activation

Determination of the activation parameters for the acid-, base-, and enzyme-catalyzed isomerizations of androst-5-ene-3,17-dione has revealed that the facility of the enzymic process is mainly due to an extremely low enthalpy of activation of 5.0 kcal mole−1. Further circumstantial evidence regarding the nature of the reacting groups at the active center has also been obtained, and a mechanism of enzyme action is proposed employing tyrosine and histidine as the principal amino acids responsible for catalyzing the isomerization.

scholarly journals The Kinetics of Plastic Flow

1980 ◽  
Vol 35 (11) ◽  
pp. 1152-1161
Author(s):  
B. Faucher ◽  
A. S. Krausz
Keyword(s):  
Plastic Flow ◽  
Activation Parameters ◽  
Initial Step ◽  
Deformation Mechanisms ◽  
Plastic Strain Rate ◽  
Qualitative Comparison ◽  
Deformation Kinetics ◽  
Functional Forms ◽  
Kinetics Of

Abstract The plastic flow associated with the three main methods of combining deformation mechanisms is described in terms of deformation kinetics. It is shown that the determination of the deformation kinetics as the initial step in the analysis is indispensable to the establishment of the activation parameters in functional forms. To this purpose, the effects of stress and temperature on the plastic strain rate are determined for three types of combined mechanisms, and qualitative comparison with experimental results is presented.

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