Elementary reaction

About: Elementary reaction is a research topic. Over the lifetime, 2972 publications have been published within this topic receiving 76110 citations.

Disulfiram-like reaction to a cephalospolin.

Abstract: To the Editor.— The disulfiram reaction to ethanol usually lasts a couple of hours and is characterized by a flushed face and a feeling of warmth. Often nausea, vomiting, sweating, and headaches occur. Rarely, hypotension, syncope, vertigo, or chest pains develop. Besides disulfiram, these reactions are known to occur after chlorpropamide, where the tendency to flush after alcohol appears to be inherited as an autosomal dominant trait.1The antiprotozoal agent, metronidazole, may cause similar reactions. Cefoperazone is a new semisynthetic parenteral cephalosporin. We recently administered cefoperazone to 24 healthy male volunteers as part of a tolerance-kinetics study. After a week of infusions, several of the subjects noted a peculiar facial flushing and tachycardia (to 180 beats per minute) occurring two to three days after discharge and within a few minutes after drinking one or two glasses of beer. We then deliberately challenged five other subjects 36 hours after their

A Computer Program Package for the Analysis, Creation, and Estimation of Generalized Reactions—GRACE. I. Generation of Elementary Reaction Network in Radical Reactions—GRACE(I)

Abstract: The system GRACE generates elementary reaction networks for simple reactions including free radicals, ions and even active sites in heterogeneous catalysis, and also predicts the overall reaction rates and the product distributions in radical reactions in the gas phase where the Arrhenius parameters of elementary reactions are available. In this paper, A/GRACE (part A of GRACE) is explained, which prepares elementary reaction networks for radical reactions. The reactant and the product are represented by square symmetric matrices. The off-diagonal elements represent bond multiplicity, or the number of localized electrons, between corresponding atoms, whereas the diagonal elements imply the number of unshared electrons on radical atoms. A reacting system, an ensemble of the participating molecules, is composed of atom groups, each of which consists of a center atom (usually non-hydrogen) and attached hydrogen atom(s), if any. Firstly, all the possible changes in the atom groups are selected, and the permit...

Kinetic theory of bimolecular reactions in liquid. II. Reversible reaction A+B⇄C+B

Abstract: A theoretical formalism based on the fully renormalized kinetic theory is applied to a diffusion-influenced pseudo-first order reaction kinetics of reversible bimolecular reaction A+B⇄C+B including unimolecular decay processes. Linear response of the system, initially at equilibrium, to a thermal perturbation is examined and a rate kernel equation for the reactant concentrations is derived. The rate kernel has a hierarchical structure and the propagator appeared in the kernel expression is truncated by a disconnected approximation. When the unimolecular reactions are turned off, the response of the system is found to be the effective irreversible survival probability. In this way, many-body complications inherent to the history of reactive pair creation are properly implemented in the description of the reversible kinetics. We compare the present theory with the other existing theories such as the rate equation, the superposition approximation, and the convolution approaches. In some limiting cases, results obtained from the present theory can be reduced to those from the existing theories. For the present reaction scheme, we found that the description of the above many-body complications in the present theory lead to the equivalent result as in the rate equation approach.

Computation of shock-induced combustion using a detailed methane-air mechanism

Abstract: The shock-induced combustion of methane-air mixtures in hypersonic flows is investigated using a new reaction mechanism consisting of 19 reacting species and 52 elementary reactions. This reduced model is derived from a full kinetic mechanism via the detailed reduction technique. Zero-dimensional computations of several shocktube experiments are presented first. The computed values for ignition delay and flame speed are in close agreement with experimental data and with results obtained using a full mechanism. The new reaction mechanism is then combined with a fully implicit Navier-Stokes CFD code to simulate two-dimensional and axisymmetric shock-induced combustion experiments of stoichiometric methane-air mixtures at a Mach number of M = 6.61. Good agreement with the experiments is obtained. Furthermore, it is shown that previous calculations were unable to accurately predict this type of flow due to their use of severely limited reduced chemical mechanisms. Finally, applications to the ram accelerator concept are also presented, based on a novel double-ramp configuration.