Theoretical Rate Constant for Thermal Unimolecular Reactions in a Multilevel System

1966 ◽  
Vol 45 (1) ◽  
pp. 216-223 ◽  
Author(s):  
W. G. Valance ◽  
E. W. Schlag
Keyword(s):  
Rate Constant ◽  
Multilevel System ◽  
Unimolecular Reactions

Fall-off shape and incubation times in weak-collision thermal unimolecular reactions

1984 ◽  
Vol 62 (1) ◽  
pp. 157-161 ◽  
Author(s):  
H. O. Pritchard
Keyword(s):  
Rate Constant ◽  
Collision Efficiency ◽  
Unimolecular Reactions ◽  
Thermal Reactions ◽  
Efficiency Factors ◽  
New Formula ◽  
Relaxation Structure

A new formula for the weak-collision unimolecular rate constant is readily interpretable in terms of bottleneck concepts. This formula is used to explore the correlation between variations in relaxation structure and fall-off shape in weak-collision thermal unimolecular reactions; some information is also presented relating to collision efficiency factors βc, and to incubation times.It is conjectured that randomisation failure is an important feature which causes near-Lindemann behaviour to occur in practical weak-collision thermal reactions.

Studies in energy transfer II. The isomerization of cyclo propane—a quasi-unimolecular reaction

1953 ◽  
Vol 217 (1131) ◽  
pp. 563-571 ◽  
Keyword(s):  
Energy Transfer ◽  
Rate Constant ◽  
Reaction System ◽  
Thermal Isomerization ◽  
Unimolecular Reaction ◽  
Unimolecular Reactions

The thermal isomerization of cy clopropane to propylene is a homogeneous unimolecular reaction at 490° C and at pressures down of 0·007 cm. The rate constant of the unimolecular reaction falls off by a factor of ten as the pressure in the reaction system is decreased from 8·4 to 0·007 cm. The results are compared with various theories of quasi-unimolecular reactions. The addition of a non-reacting gas to the system counteracts the falling off. The relative efficiencies of a number of gases for maintaining the unimolecular rate constant have been measured.

A COMPARISON OF SLATER'S THEORY OF UNIMOLECULAR REACTIONS WITH EXPERIMENTAL DATA

1959 ◽  
Vol 37 (6) ◽  
pp. 1035-1037 ◽  
Author(s):  
Everett Thiele ◽  
David J. Wilson
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Lower Bounds ◽  
Rate Constant ◽  
Unimolecular Reactions ◽  
Pressure Limit ◽  
Nitrogen Pentoxide ◽  
Simplified Method ◽  
Experimental Values

Slater's theory of unimolecular reactions is tested by comparing theoretical and experimental values of the pressure at which the rate constant has fallen off from the high-pressure limit by 5%. A simplified method is used for calculating lower bounds to the theoretical value of this pressure. Agreement with experimental data on cyclobutane, cyclobutene, and nitrogen pentoxide is rather poor; experimental values are lower than the calculated lower bounds.

The kinetics of internal energy randomisation in thermal unimolecular reactions

1980 ◽  
Vol 58 (21) ◽  
pp. 2236-2245 ◽  
Author(s):  
Huw Owen Pritchard
Keyword(s):  
Internal Energy ◽  
Lower Limit ◽  
Rate Constant ◽  
Rate Constants ◽  
Rate Function ◽  
Second Order ◽  
Specific Rate ◽  
Unimolecular Reactions ◽  
Methyl Isocyanide ◽  
Kinetics Of

The aim of this paper is to present a minimal theory of thermal unimolecular reactions, including explicitly the kinetics of intramolecular randomisation processes. A quasi-diatomic model is formulated and, within the framework of the model, both first-and second-order randomisation processes among reactant and product states are examined.It is concluded that a vital mechanism for the intramolecular energy randomisation in thermal unimolecular reactions is a collisional one. On this assumption, a straightforward derivation of the Polanyi–Wigner specific rate function, as we have reinterpreted it, becomes possible.At the same time, anomalies in the fall-off curves for the thermal isomerisations of methyl isocyanide and ethyl isocyanide can be accounted for very simply: in the former case, values for both the first- and second-order randomisation rate constants can be derived, but in the latter case it is only possible to establish a lower limit for the second-order randomisation rate constant.

Functional Properties of p-Anisoylated Plasmin-Staphylokinase Complex

1993 ◽  
Vol 70 (02) ◽  
pp. 326-331 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
R A G Smith ◽  
D Collen
Keyword(s):  
Human Plasma ◽  
Rate Constant ◽  
Time Course ◽  
Bolus Injection ◽  
Similar Rate ◽  
Clot Lysis ◽  
Lag Phase ◽  
Plasma Clot ◽  
Rapid Clearance ◽  
Stoichiometric Complex

SummaryThe kinetic and fibrinolytic properties of a reversibly acylated stoichiometric complex between human plasmin and recombinant staphylokinase (plasmin-STAR complex) were evaluated. The acylation rate constant of plasmin-STAR by p-amidinophenyl-p’-anisate-HCI was 52 M-1 s-1 and its deacylation rate constant 1.2 × 10-4 s-1 (t½ of 95 min) which are respectively 50-fold and around 3-fold lower than for the plasmin-streptokinase complex. The acylated complex was stable as evidenced by binding to lysine-Sepharose. However, following an initial short lag phase, the acylated plasmin-STAR complex activated plasminogen at a similar rate as the unblocked complex, whereas the acylated plasmin-streptokinase complex did not activate plasminogen. These findings indicate that STAR, unlike streptokinase, dissociates from its acylated complex with plasmin in the presence of excess plasminogen. In agreement with this hypothesis, the time course of the lysis of a 125I-fibrin labeled plasma clot submerged in citrated human plasma, is similar for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR (50% clot lysis in 2 h requires 12 nM of each agent). The plasma clearances of STAR-related antigen following bolus injection in hamsters were 1.0 to 1.5 ml/min for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR, as a result of short initial half-lives of 2.0 to 2.5 min.The dissociation of the anisoylated plasmin-STAR complex and its consequent rapid clearance suggest that it has no apparent advantages as compared to free STAR for clinical thrombolysis.

ALGORITHMS OF OPERATION AND SOFTWARE OF MULTILEVEL SYSTEM FOR MONITORING AND TECHNICAL DIAGNOSTICS OF ELECTRICAL POWER FACILITIES EQUIPMENT

2016 ◽  
Vol 2016 (4) ◽  
pp. 86-88 ◽  
Author(s):  
M.V. Myslovych ◽  
◽  
R.M. Sysak ◽  
L.B. Ostapchuk ◽  
Yu.I. Gyzhko ◽  
...  
Keyword(s):  
Electrical Power ◽  
Technical Diagnostics ◽  
Multilevel System
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