The determination of electron capture rate constants by the study of photocurrent systems in the non-steady state

AbstractWe review three important experimental results which suggest that electron capture and emission by the DX center in AlxGa1-xAs proceeds via an excited intermediate state: the very different dependencies of the thermal capture and emission rates on alloy composition, the exponential dependence of the thermal capture rate on the quasi-equilibrium Fermi energy, and the thermal activation of the hot electron capture rate. None of these results is readily explained by a conventional lattice relaxation model, in which an electron is captured directly from the lowest lying band edge, but each can be simply explained if the dominant channel for multiphonon capture is via a transition state which lies well above the band edge. This picture is consistent with recent pseudopotential calculations which predict that the lattice relaxed state (the DX state) is stabilized by capture of more than one electron, since such a model naturally admits the possibility of an intermediate one-electron state.

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Determination of the steady-state turnover rates of the metabolically active pools of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate in human erythrocytes

Biochemical Journal ◽

10.1042/bj2590893 ◽

1989 ◽

Vol 259 (3) ◽

pp. 893-896 ◽

Cited By ~ 17

Author(s):

C E King ◽

P T Hawkins ◽

L R Stephens ◽

R H Michell

Keyword(s):

Steady State ◽

Rate Constants ◽

Human Erythrocytes ◽

Turnover Rates ◽

Metabolic Fluxes ◽

Metabolic Pool ◽

Phosphatidylinositol 4 ◽

Kinetics Of ◽

Phosphate Groups

When intact human erythrocytes are incubated at metabolic steady state in a chloride-free medium containing [32P]Pi, there is rapid labelling of the gamma-phosphate of ATP, followed by a slower labelling of the monoester phosphate groups of phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] [King, Stephens, Hawkins, Guy & Michell (1987) Biochem. J. 244, 209-217]. We have analysed the early kinetics of the labelling of these phosphate groups, in order to determine: (a) the steady-state rates of the interconversions of phosphatidylinositol, PtdIns4P and PtdIns(4,5)P2; and (b) the fractions of the total cellular complement of PtdIns4P and PtdIns(4,5)P2 that participate in this steady-state turnover. The experimental data most closely fit a pattern of PtdIns4P and PtdIns(4,5)P2 turnover in which one-quarter of the total cellular complement of each lipid is in the metabolic pool that participates in rapid metabolic turnover, with rate constants of 0.028 min-1 for the interconversion of PtdIns and PtdIns4P, and of 0.010 min-1 for the PtdIns4P/PtdIns(4,5)P2 cycle. These rate constants represent metabolic fluxes of approx. 2.1 nmol of lipid/h per ml of packed erythrocytes between PtdIns and PtdIns4P and of approx. 5.7 nmol/h per ml of cells between PtdIns4P and PtdIns(4,5)P2.

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Nuclear electron capture rate in stellar interiors and the case of7Be

Journal of Physics G Nuclear and Particle Physics ◽

10.1088/0954-3899/36/2/025203 ◽

2008 ◽

Vol 36 (2) ◽

pp. 025203 ◽

Cited By ~ 5

Author(s):

P Quarati ◽

A M Scarfone

Keyword(s):

Electron Capture ◽

Capture Rate ◽

Electron Capture Rate ◽

Stellar Interiors

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