Effects of large first-order static quadrupole splittings on 1/2 → -1/2 exponential spin-resonance decay rates

1976 ◽  
Vol 13 (7) ◽  
pp. 2768-2772 ◽  
Author(s):  
Peter A. Fedders
Keyword(s):  
Decay Rates ◽  
First Order ◽  
Resonance Decay ◽  
Spin Resonance ◽  
Static Quadrupole

An Electron Spin Resonance Study of Some Reactions of Pentafluorosulfuranyl (SF5)

1975 ◽  
Vol 53 (16) ◽  
pp. 2361-2364 ◽  
Author(s):  
John Charles Tait ◽  
James Anthony Howard
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Rate Constants ◽  
Arrhenius Equation ◽  
Kinetic Studies ◽  
Electron Spin Resonance Study ◽  
Order Process ◽  
First Order ◽  
Spin Resonance ◽  
Spin Resonance Study

A kinetic electron spin resonance study of the self-reaction of SF5 and a spectroscopic and kinetic e.s.r. study of the reaction of SF5 with 1,1-di-t-butylethylene are reported. This radical undergoes self-reaction by a second-order process and the rate constants are given by the Arrhenius equation log 2k1(M−1 s−1) = (10.3 ± 0.5) − (1.7 ± 0.5)/θ where θ = 2.303RT kcal mol−1. It adds to 1,1-di-t-butylethylene to give (t-Bu)2CCH2SF5 which decomposes by a first-order process with rate constants that obey the expression log k2(s−1) = (13 ± 0.4) − (10 ± 0.2)/θ. Both these rate constants are pertinent to kinetic studies of the photoinduced addition of SF5C1 to olefins.

Tube electrode and electron spin resonance. First-order kinetics

1980 ◽  
Vol 76 (0) ◽  
pp. 1391 ◽  
Author(s):  
W. John Albery ◽  
Richard G. Compton ◽  
Andrew T. Chadwick ◽  
Barry A. Coles ◽  
Jan A. Lenkait
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
First Order ◽  
First Order Kinetics ◽  
Tube Electrode ◽  
Spin Resonance

Two-photon decay rates of hydrogenlike ions revisited by using Dirac-Coulomb Sturmian expansions of the first order

2014 ◽  
Vol 89 (2) ◽  
Author(s):  
Zachée Bona ◽  
Hugues Merlain Tetchou Nganso ◽  
Thierry Blanchard Ekogo ◽  
Moïse Godfroy Kwato Njock
Keyword(s):  
Decay Rates ◽  
First Order ◽  
Two Photon ◽  
Photon Decay

Fibrinogen Attentuates Thrombin Decay In a Concentration-Dependent Manner

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2346-2346 ◽  
Author(s):  
Romy Kremers ◽  
Rob Wagenvoord ◽  
Coenraad Hemker
Keyword(s):  
Decay Rate ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Decay Rates ◽  
Plasma Fibrinogen ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Human Fibrinogen ◽  
First Order ◽  
Pseudo First Order

Abstract Introduction Clotting of blood(-plasma) is caused by the first traces of thrombin that appear. The bulk of thrombin emerges in the clot and is subsequently inactivated. Fibrin(-ogen) has a stimulatory effect on the amount of thrombin activity observed. This can be due to stimulation of prothrombin conversion, to attenuation of thrombin inhibition or both. Thrombin is known to bind reversibly to specific sites on the E domain of fibrin and to remain active when bound. We tested the hypothesis that this binding makes thrombin less accessible to inhibitors and thus fosters the presence of active thrombin. Thrombin decay is caused by serpins, mainly antithrombin (AT), and by α2Macroglobulin (α2M). Aim In this study we aim to determine the effect of fibrin(-ogen) on the rate of thrombin decay and on the contribution of α2M to total decay. Methods Thrombin generation (TG) in normal pool plasma in the presence or absence of fibrinogen was triggered with 5 pM tissue factor (TF) and measured by calibrated automated thrombinography (CAT). Thrombin decay was measured by triggering thrombin generation with high (50 pM) tissue factor (TF) causing all prothrombin to be converted within 3 minutes, so that the part of the curve after 3 min is governed by thrombin decay alone. Total thrombin decay rate was calculated as the pseudo first order decay constant of that part of the curve. The α2M-dependent thrombin decay rate was measured as the pseudo first order constant with which the amidolytically active α2M-thrombin complex forms. AT and α2M levels were determined by functional assays that were developed in house. Fibrinogen was measured by the von Clauss method. Defibrination was done by adding reptilase and winding out the formed fibrin. Anonymized plasma samples remaining from routine analyses were obtained from the clinical routine laboratory (n=77), including samples from patients in which a shift in the ratio of AT and α2M could be expected (liver cirrhosis, nephrotic syndrome). Pearson’s correlation analysis was used to establish the relationships between thrombin decay rates and inhibitor concentrations, and the influence of plasma fibrinogen concentration on these reactions. Results Thrombin generation and thrombin decay were measured in normal pooled plasma, defibrinated normal pooled plasma and defibrinated normal pooled plasma spiked with 1, 2 or 3 g/L purified human fibrinogen. The removal of fibrinogen from plasma decreases thrombin generation by 40% (p<0.001) and the addition of purified human fibrinogen to defibrinated plasma concentration-dependently restores TG. In addition, plasma defibrination causes the rate of total thrombin decay to increase significantly from 0.36 min-1 to 0.47 min-1 (p<0.001). This effect can be reversed as well by the addition of purified human fibrinogen. Thrombin decay by α2M is inhibited by fibrinogen in a concentration-dependent manner (36% at 3 g/L fibrinogen) (p<0.001). No significant concentration dependence was found for AT-dependent decay. In the patient samples fibrinogen levels varied between 1.20 and 4.79 g/L with a mean value of 2.79 g/L (± 0.62 g/L). AT concentrations ranged from 0.58 µM to 3.08 µM and α2M levels from 1.85 µM to 7.73 µM. Both total and AT-dependent thrombin decay rates were significantly correlated with the plasma AT levels (p<0.001) and α2M-dependent thrombin decay was significantly correlated with the plasma α2M concentration (p<0.001). Plasma fibrinogen levels were significantly and inversely correlated with the rate of thrombin decay by α2M, but not AT (p=0.001). Conclusion The presence of fibrin(-ogen) decreases the decay rate of thrombin in a concentration-dependent manner, primarily by its influence on α2M-dependent thrombin inactivation. This causes thrombin generation to increase. Together, these results suggest that elevated fibrinogen levels may predispose individuals to thrombosis by protecting thrombin. Disclosures: No relevant conflicts of interest to declare.

MOLECULAR RESONANCES AND THE JACOBI SHAPE TRANSITION: THE CASE OF 24Mg+24Mg AND 48Cr

2008 ◽  
Vol 17 (10) ◽  
pp. 2029-2033 ◽  
Author(s):  
MARIE-DELPHINE SALSAC ◽  
FLORENT HAAS
Keyword(s):  
High Spin ◽  
Ground State ◽  
Molecular State ◽  
Shape Transition ◽  
Resonance Decay ◽  
Spin Resonance ◽  
Molecular Resonances ◽  
Bombarding Energy ◽  
Fast Rotating

A fast rotating 48 Cr is predicted to be highly prolate and deformed after a Jacobi shape transition and just before fission. In this article, it is proposed that a narrow and high spin 24 Mg +24 Mg resonance corresponds to the formation of this exotic 48 Cr . Moreover the 24 Mg +24 Mg reaction has been studied at the Legnaro Tandem at a CM bombarding energy of 45.7 MeV, where a narrow and high spin resonance has been reported previously. To establish the connection between the resonance and a molecular state of 48 Cr , the decay of the resonance into the inelastic and fusion-evaporation channels has been investigated. The ON and OFF resonance decay yields have been measured using, for the inelastic channels, the fragment spectrometer PRISMA and the γ array CLARA, and, for the fusion-evaporation channels, the Si array EUCLIDES and the γ array GASP. Strong resonant effects have been observed in the inelastic channels involving the 2+ and 4+ states of the 24 Mg ground state (g.s.) band. Weaker effects are also seen in certain fusion-evaporation channels. Both results will be discussed here.

An Electron Spin Resonance Study of the Arylsilyl Adducts of Phenyl tert-Butyl Nitrone and Their Decomposition Kinetics

1974 ◽  
Vol 52 (16) ◽  
pp. 2901-2905 ◽  
Author(s):  
Babatunde B. Adeleke ◽  
Sau-King Wong ◽  
Jeffrey K. S. Wan
Keyword(s):  
Decomposition Kinetics ◽  
Electron Spin Resonance Study ◽  
Silyl Group ◽  
First Order ◽  
Tert Butyl ◽  
First Order Kinetics ◽  
Spin Resonance ◽  
Butyl Peroxide ◽  
The Stability ◽  
Spin Resonance Study

The formation and the stability of some arylsilyl adducts of phenyl tert-butyl nitrone were studied in a photochemical system using di-tert-butyl peroxide as solvent. The β-proton splittings of all the arylsilyl adducts, ranging from 5.6 to 8.3 G, are relatively larger than their carbon analogs, which are usually less than 4 G. The arylsilyl adducts are found to decompose in di-tert-butyl peroxide solvent by a first-order kinetics. The activation energy involved in the decomposition of a series of arylsilyl adducts varies from about 14 to about 9 kcal/mol, as the size of the silyl group increases. In all cases, very low values of the A factors (between 106 and 1010) were observed.

Substituent effects on the electronic spectra of aromatic hydrocarbons II. The quantitative determination of the inductive effect on π-electrons

1964 ◽  
Vol 278 (1372) ◽  
pp. 64-70 ◽  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Substituent Effects ◽  
Negative Ion ◽  
First Order ◽  
Spin Resonance ◽  
Inductive Effects ◽  
Inductive Parameter ◽  
Relationship Of ◽  
The Relationship

The inductive effects of substituent groups on the π-electrons of aromatic hydrocarbons are estimated quantitatively from electronic spectroscopic data. Two methods are used to evaluate the parameters. The first is based on the first-order changes in the energy of the first transition of azulene on mono-substitution and the second is based on the second-order changes in the energy of the first transition of benzene on poly substitution. The agreement between the values obtained by the two methods is good except for acceptor substituents for which the values obtained by the first method are considerably smaller than those obtained by the second. Using these values of the inductive parameter we have calculated the splitting of the ground state of the benzene negative ion brought about by substituents; and the relationship of this splitting to the electron spin resonance spectra of these ions is discussed.

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