Role of ionic strength in the kinetics of formation of the monochelate of nickel(II) with heptane-3,5-dione

1992 ◽  
Vol 24 (4) ◽  
pp. 359-368 ◽  
Author(s):  
María Luisa Moyá ◽  
Amalia Rodriguez ◽  
Francisco Sánchez ◽  
Carlos Blanco ◽  
Michael J. Hynes
Keyword(s):  
Ionic Strength ◽  
Kinetics Of Formation ◽  
Kinetics Of

scholarly journals Studies on Pitting Corrosion of Al–Cu–Li Alloys Part III: Passivation Kinetics of AA2098–T851 Based on the Point Defect Model

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1912 ◽  
Author(s):  
Elmira Ghanbari ◽  
Alireza Saatchi ◽  
Xiaowei Lei ◽  
Digby D. Macdonald
Keyword(s):  
Barrier Layer ◽  
Potential Model ◽  
Electrochemical Impedance ◽  
Passive Layer ◽  
Charge Carriers ◽  
Theoretical Interpretation ◽  
Defect Model ◽  
Kinetics Of Formation ◽  
Kinetics Of

In this paper, the passivation kinetics of AA2098–T851 was investigated by a fundamental theoretical interpretation of experimental results based on the mixed potential model (MPM). The steady state passive layer formed on the AA2098–T851 in NaHCO3 solution in a CO2 atmosphere upon potentiostatic stepping in the anodic direction followed by stepping in the opposite direction was explored. Potentials were selected in a way that both anodic passive dissolution of the metal and hydrogen evolution reaction (HER) occur, thereby requiring the MPM for interpretation. Optimization of the MPM on the experimental electrochemical impedance spectroscopy (EIS) data measured after each potentiostatic step revealed the important role of the migration of Al interstitials in determining the kinetics of passive layer formation and dissolution. More importantly, it is shown that the inequalities of the kinetics of formation and dissolution of the passive layer as observed in opposite potential stepping directions lead to the irreversibility of the passivation process. Finally, by considering the Butler–Volmer (B–V) equation for the cathodic reaction (HER) in the MPM, and assuming the quantum mechanical tunneling of the charge carriers across the barrier layer of the passive film, it was shown that the HER was primarily controlled by the slow electrochemical discharge of protons at the barrier layer/solution (outer layer) interface.

The role of divalent cations in the activation of the NADP+-specific isocitrate dehydrogenase from Pisum sativum L.

1977 ◽  
Vol 55 (9) ◽  
pp. 928-934 ◽  
Author(s):  
Robert J. Maloney ◽  
David T. Dennis
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Isocitrate Dehydrogenase ◽  
Divalent Cations ◽  
Free Form ◽  
Saturation Kinetics ◽  
The Difference ◽  
The Stability ◽  
Kinetics Of

A divalent cation electrode was used to measure the stability constants (association constants) for the magnesium and manganese complexes of the substrates for the NADP+-specific isocitrate dehydrogenase (EC 1.1.1.42) from pea stems. At an ionic strength of 26.5 mM and at pH 7.4 the stability constants for the Mg2+–isocitrate and Mg2+–NADP+ complexes were 0.85 ± 0.2 and 0.43 ± 0.04 mM−1 respectively and for the Mn2+–isocitrate and Mn2+–NADP+ complexes they were 1.25 ± 0.07 and 0.75 ± 0.09 mM−1 respectively. At the same ionic strength but at pH 6.0 the Mg2+–NADPH and Mn2+–NADPH complexes had stability constants of 0.95 ± 0.23 and 1.79 ± 0.34 mM−1 respectively. Oxalosuccinate and α-ketoglutarate do not form measureable complexes under these conditions. Saturation kinetics of the enzyme with respect to isocitrate and metal ions are consistent with the metal–isocitrate complex being the substrate for the enzyme. NADP+ binds to the enzyme in the free form. Saturation kinetics of NADPH and Mn2+ indicate that the metal–NADPH complex is the substrate in the reverse reaction. In contrast the pig heart enzyme appears to bind free NADPH and Mn2+. A scheme for the reaction mechanism is presented and the difference between the reversibility of the NAD+ and NADP+ enzyme is discussed in relation to the stability of the NADH and NADPH metal complexes.

THE KINETICS OF THE FORMATION OF THE MONOSULPHATO COMPLEX OF IRON (III) IN AQUEOUS SOLUTION

1962 ◽  
Vol 40 (9) ◽  
pp. 1836-1845 ◽  
Author(s):  
G. G. Davis ◽  
W. MacF. Smith
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Ionic Strength ◽  
Continuous Flow ◽  
Hydrogen Ions ◽  
Kcal Mole ◽  
Forward Reaction ◽  
First Order ◽  
Kinetics Of Formation ◽  
Kinetics Of

The kinetics of formation of the monosulphato complex of iron (III) has been examined spectrophotometrically using a continuous-flow technique over the range of temperatures 15.6 to 34.5 °C in an aqueous medium of ionic strength 0.5 and a range of concentrations of hydrogen ions 0.05 to 0.30 M. The experimental data may be interpreted on the assumption that the significant reactions are a bimolecular association opposed by a first-order dissociation [Formula: see text] For the forward reaction ΔH≠ is 18.0 kcal mole−1 and ΔS≠ is 19.4 cal mole−1 deg−1.

An Evaluation of the Plane Strain Compression Test. III. Experimental Study of the Friction Test: The Role of the Metallurgical Parameters of Die and Sheet

1982 ◽  
Vol 104 (4) ◽  
pp. 538-544 ◽  
Author(s):  
F. Delamare ◽  
J. Kubie´
Keyword(s):  
Experimental Study ◽  
Shear Stress ◽  
Chemical Nature ◽  
Marked Effect ◽  
Friction Test ◽  
Good Reliability ◽  
Plane Strain Compression Test ◽  
Kinetics Of Formation ◽  
Kinetics Of

This paper deals with the influence of the metallurgical parameters of dies and sheet on the friction shear-stress which could be measured by P.S.C.T. The metallurgical parameters of the dies have a marked effect on the kinetics of formation of transfer layers. The metallurgical parameters of the sheet have an effect both on the kinetics of formation, and the chemical nature of the transfer layers. Many parameters must be controlled to have good reliability in PSCT. Then the results can be correlated with boundary lubrication in cold rolling.

Kinetics of the anation reaction of nickel(II) and 1,10-phenanthroline in methanol–water mixtures

1969 ◽  
Vol 47 (20) ◽  
pp. 3773-3778 ◽  
Author(s):  
M. L. Sanduja ◽  
W. MacF. Smith
Keyword(s):  
Ionic Strength ◽  
Rate Constant ◽  
Rate Constants ◽  
Solvent Composition ◽  
Solvent Mixtures ◽  
Methanol Content ◽  
Dependent Rate ◽  
Kinetics Of Formation ◽  
Kinetics Of ◽  
Anation Reaction

The kinetics of formation of the monophenanthroline complex of nickel(II) has been studied spectrophotometrically in water–methanol mixtures of 0 to 97 weight % of methanol, at ionic strength 0.050, at varying acidities at 25 °C. Values for the rate constants for the acid independent and acid dependent reactions together with values for the equilibrium acid ionization quotient of phenanthrolium ion over the range of solvent mixtures have been determined. The values of the acid independent rate constant show little dependence on solvent compositions up to 76% methanol, then decrease and show no correlation with trends in the ionization quotient of phenanthrolium ion. The acid dependent rate constant shows only a modest dependence on solvent composition over most of the range of solvent compositions except in the range of highest methanol content where it is not significantly different from zero.

Kinetics of Formation and Dissolution of Weak Polyelectrolyte Multilayers:  Role of Salt and Free Polyions

Langmuir ◽  
2002 ◽  
Vol 18 (14) ◽  
pp. 5607-5612 ◽  
Author(s):  
D. Kovacevic ◽  
S. van der Burgh ◽  
A. de Keizer ◽  
M. A. Cohen Stuart
Keyword(s):  
Polyelectrolyte Multilayers ◽  
Kinetics Of Formation ◽  
Kinetics Of

Kinetic- or Thermodynamic-Growth Formation of Pd Nanocrystals: a combined TEM-DLS Approach

2008 ◽  
Vol 1087 ◽  
Author(s):  
Gilles Berhault ◽  
Marta Bausach
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Growth Kinetics ◽  
Palladium Nanoparticles ◽  
Theory Model ◽  
Collision Theory ◽  
Kinetics Of Formation ◽  
Growth Formation ◽  
Kinetics Of

AbstractThe kinetics of formation of palladium nanoparticles with well-defined morphologies (rods, cubes, MTP icosahedra, bipyramids) was studied using a combination of TEM and dynamic light scattering (DLS). The present study was focused on the role of the concentration and the size of seeds on both the kinetics of growth and the morphology distribution. Results clearly emphasize the role of the seed concentration (and not the size) on the growth kinetics in agreement with a collision theory model.

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