Estimating the applicability of kinetic schemes in hydrogen combustion simulation in combustion chambers of aircraft engines

This paper presents the results of numerical simulation of hydrogen combustion in a supersonic flow of an oxidizing medium in a model combustion chamber using various models of chemical kinetics. The best scheme, which most accurately describes the combustion processes, is revealed. Comparison of the calculated distribution of molar fractions with experimental data is carried out, and relative deviations for the piloted mode of operation of the chamber are obtained.

Self-Voluntary Polymerization with Formation of Quaternary Ammonium Groups

The reaction of spontaneous polymerization in the N, N-dialkylaminoethyl methacrylate - alkyl halide system in organic solvent solutions is considered. It is shown that polymerization in the system under study begins only after the formation of quaternary ammonium salt in the reaction medium (at a concentration of about 0.2 mol/L) by the Menshutkin reaction, as a result of quaternization of the unsaturated amine with an alkyl halide. For the explanation of the aggregate of the obtained experimental data, fundamental considerations were formulated, kinetic schemes were developed, and the corresponding mechanism of polymerization processes was proposed.

The strategy developed for high conversion and the multiplicity problems of biochemical reaction in a real CSTR with Cholette’s model

In this paper we used the examples for four kinetic schemes under substrate and product inhibition of a biochemical reaction occurring in a real CSTR with Cholette’s model to demonstrate the strategy for high conversion and the multiplicity problem. In addition, it is found that the non-ideal mixing indeed influences the necessary and sufficient conditions for input multiplicity and output multiplicity. Meanwhile, for each of four kinetic schemes under substrate and product inhibition of a biochemical reaction, the input multiplicity regions are found inside the output multiplicity regions. This fact reveals that when deriving an operating strategy to obtain a high conversion and to avoid the control problem, only the output multiplicity is needed to consider even in the CSTR with the input and output multiplicity occurring simultaneously.

Unravelling the intricate cooperativity of subunit gating in P2X2 ion channels

Ionotropic purinergic (P2X) receptors are trimeric channels that are activated by the binding of ATP. They are involved in multiple physiological functions, including synaptic transmission, pain and inflammation. The mechanism of activation is still elusive. Here we kinetically unraveled and quantified subunit activation in P2X2 receptors by an extensive global fit approach with four complex and intimately coupled kinetic schemes to currents obtained from wild type and mutated receptors using ATP and its fluorescent derivative 2-[DY-547P1]-AET-ATP (fATP). We show that the steep concentration-activation relationship in wild type channels is caused by a subunit flip reaction with strong positive cooperativity, overbalancing a pronounced negative cooperativity for the three ATP binding steps, that the net probability fluxes in the model generate a marked hysteresis in the activation-deactivation cycle, and that the predicted fATP binding matches the binding measured by fluorescence. Our results shed light into the intricate activation process of P2X channels.