Self-inhibition

Clean metallic aluminum is extremely reactive. Even exposure to air at ordinary temperatures is sufficient to promote immediate oxidation. This reactivity is self-inhibiting, however, which determines the general corrosion behavior of aluminum and its alloys due to the formation of a thin, inert, adherent oxide film. In view of the great importance of the surface film, it can be thickened by anodizing in a bath of 15% sulfuric acid (H2SO4) solution or by cladding with a thin layer of an aluminum alloy containing 1 % zinc. 

Rebec, G.V. Curtis, S.D. and Zimmerman, K.S. Dorsal raphe neurons Self-inhibition by an amphetamine-induced release of endogenous serotonin. Brain Res 251 374-379, 1982. 

By surface science techniques, Mullins and Overbury showed that the presence of reduced ceria might create new active sites for NO dissociation [82], The degree of decomposition is increased and the onset temperature for decomposition is reduced when Rh is supported on reduced ceria (Rh/CeOj compared to Rh on oxidized ceria (Rh/Ce02) NO dissociation being self-inhibiting. 

In the later stages, the oxidation of hydrocarbons is often self-inhibited due to the accumulation of such oxidation products that retard chain oxidation. Each hydrocarbon has the individual peculiarities of oxidation including the mechanism of self-inhibition. A few of such main peculiarities will be mentioned here [3,56]. 

The accumulation of hydroxyl-containing products, such as hydroperoxides, alcohols, acids, and water, also reduce the total activity of peroxyl radicals due to the hydrogen bonding with R02 [150], When acting together, these factors cause self-inhibition of autoxidation at conversion levels of 40-50% [3],... 

Paul This is particularly the case in vascular tissue where this suppression can be maintained for hours. We have to get back to the calculation of how much the SR can hold. When I did the KC1 contractions, my expectation was that I would saturate the SR in a reasonable period of time that it couldn t take up any more Ca2+ because it would be self-inhibited. This was going to be my control. It was both disappointing and exciting to find out that the shift was maintained and disappeared with CPA. I am going back to the sort of vectorial unloading... 

Bonhoeffer and Farkas estimated k3/k2 100 and claimed that at 15 % decomposition the photolysis is completely self inhibited. More recent work by Ogg and Williams9,10 showed that for the photolysis with 2537 A radiation, k3/k2 is independent of HI pressure (50-150 torr), independent of temperature and has a value 3.5+0.3. The effect of cyclohexane as an inert diluent11 was to increase k3/k2 to 7.0+0.4 at 155°, which value remained constant at high cyclohexane hydrogen iodide ratios. This result was attributed to collisional thermalisation of the hot H atoms produced by 2537 A radiation and this limiting high-pressure value of k3/k2 = (k3/k2)aa was considered to be that for thermally equilibrated H atoms. 

A major product in the combustion of all organic sulfur compounds is sulfur dioxide. Sulfur dioxide has a well-known inhibiting effect on hydrocarbon and hydrogen oxidation and, indeed, is responsible for a self-inhibition in the oxidation of organic sulfur compounds. This inhibition most likely arises from its role in the removal of H atoms by the termolecular reaction... 

Structures such as (26) were demonstrated [103] to he fairly easily reduced at a Pt electrode. Thus, when R = Ph, an anion radical (E° = —1.26 V vs Ag/Agl/I 0.1 M) of high stahihty is formed. However, macroelectrolyses of the compounds (26) could not he achieved at all since whatever the amount of electricity passed through the cell, the starting material was totally recovered. The compounds (26) are expected to react slowly with the tetraalky-lammonium salt R4N+ and the reaction would correspond to an indirect reduction of the electrolyte. Compounds (26), with R = primary alkyl groups, led - even in DMF-to strong self-inhibition explained by the adsorption of produced... 

On the other hand, the reaction order with respect to methyl acetate was -1.7. The strong self-inhibition effect of methyl acetate should be noted, because of stronger adsorption of methyl acetate on Ni/A.C. than other reactants. 

The least strongly sorbed reactant in HDS processes is dihydrogen. It could well be that the major reason for rate reduction by inhibitors is prevention of dihydrogen adsorption by competing molecules. This would include the sulfur-containing reactant as well. This would explain the phenomenon of self-inhibition in HDS reactions. 

Mention has already been made of the relatively small reactivity of allyl peroxy radicals compared with other alkyl peroxy radicals. Jost (88, 96) has reasoned that paraffins react by a small number of long chains, whereas olefins oxidize by a large number of short chains. Olefins are thus attacked more readily than paraffins but form less reactive allyl radicals. In addition, during oxidation chain transfer occurs in which alkyl radicals are replaced by allyl radicals. Shorter chains would then be expected. Comparison of the precombustion products of iso-octane and diisobutylene (154) indicates that marked self-inhibition of reaction chains was occurring in the latter case. 

Detailed kinetic studies of some aprotie systems were reported by Bamford s group. The kinetics of the polymerisation initiated by sodium salt of dihydrocinnamic acid in N-methyl-formamide exhibits a few interesting features. Typical conversion curves for D,L-phenyl alanine and y-benzyl-L-glutamate NCA s are shown in Fig. 10 taken from the paper by Ballard and BamfoRD (54). For a low concentration of the salt, the reaction is self-inhibited, i. e. a relatively rapid polymerisation ceases after a while (curve C) when a substantial fraction of the still... 

If complete adsorptive molecular layers inhibit further dissolution of silicic acid, all experimental phenomena are explicable. In this case the final experimental concentration is not a saturation concentration which can be obtained also from high initial concentrations of silicic acid. Instead, the concentration will decrease only to the extent that the adsorption equilibrium is established. For sufficiently high initial concentrations of silicic acid and comparatively small surface areas, this will involve a multimolecular layer, whose equilibrium concentration is higher than the final experimental concentration of the self-inhibiting dissolution process. 

The decrease in a0 with increasing aluminum content is consistent with the lower acidity of X zeolite in comparison with the lower aluminum content Y zeolite. The observed acidity decrease with increasing aluminum content was interpreted as a self-inhibition of the acidic sites as their number increases. Such a phenomenon is also consistent with the electrostatic field calculations of Pickert et al. (202) and Dempsey (203), who found that for a cation at a given distance from a cation site the electric field is smaller for X zeolite than for Y. 

Bacci A, Huguenard JR, Prince DA (2004) Long-lasting self-inhibition of neocortical intemeurons mediated by endocannabinoids. Nature 431(7006) 312-16... 

A very important mechanism of control of 5-HT neurons is self-inhibition through 5-HT1A receptors. Initial studies found that there is a poststimulus... 

Fermentation is typically conducted in dilute suspension culture. The low concentration in such systems limits reaction efficiency, and the presence of particulate and colloidal solids poses problems for product recovery and purification. By circulating the fermentation broth through an ultrafiltration system, it is possible to recover product continuously as they are generated while minimizing loss of enzyme or cells and keeping product concentration in the bioreactor below the self-inhibition level for the biocatalyst. This process is referred to as perfusion. As the ultrafiltration unit is part of the production process, the entire system is often considered a membrane reactor. 

It has also been shown that aromatic hydrocarbon degradation maybe self-inhibited. That is, the rate of degradation of the hydrocarbon is slowed by high concentrations of the hydrocarbon itself [29,32]. Self-inhibition may be modeled by incorporating Haldane (or Andrews) kinetics into the Monod expression ... 

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