Influence of effective chemical reaction rate constants on the process of supersonic flow deceleration in a channel

2020 ◽  
Author(s):  
V. P. Zamuraev ◽  
A. P. Kalinina
1995 ◽  
Vol 88 (2-3) ◽  
pp. 344-346 ◽  
Author(s):  
Wei-Ping Hu ◽  
Gillian C. Lynch ◽  
Yi-Ping Liu ◽  
Ivan Rossi ◽  
James J.P. Stewart ◽  
...  

Author(s):  
Natalia I. Belaia ◽  
Aleksandr V. Belyi ◽  
Viktoriya A. Kletsova

Using the chronovoltammetric method it was shown that on a mercury film electrode in an acidic medium the reduction of oxygen to hydrogen peroxide in the presence of flavonoids is realized as a reversible electrode process followed by a first-order limiting chemical reaction with the participation of the primary product of the electrode reaction – the hydroperoxyl radical. For this type of reaction, in the case of reduction processes, the peak of potential shifts relative to the reversible half-wave potential in the direction of positive potentials. This shift is the larger then the higher the rate constant of the subsequent chemical reaction and the lower the sweep speed of the polarization voltage. To calculate the constants, the half-wave potential of oxygen electroreduction is determined without the addition of a flavonoid. Its value equals to –0.27 V and can be used both in acidic and alkaline media, since it does not change on mercury electrodes in the pH range of 1–9. The reaction rate constants of flavonoids with hydroperoxyl are a characteristic of their antiradical activity. The flavonone groups are the most reactive towards the radical compounds – morin and myricetin. For all studied compounds, the number of electrons participating in the limiting stage varies from 0.96 to 1. This indicates the occurrence of an elementary chemical act of a flavonoid with a radical and the absence of an effect on the kinetics of the investigated reaction of the products of the conversion of flavonoids. The applicability of the presented method for calculating the rate constants to reactions involving active oxygen forms is confirmed by the presence of a high correlation between the data obtained and the reaction rate constants of flavonoids with 2,2′-diphenyl-1-picrylhydrazyl radical.


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