Other Shock-Induced Reactions

Shock waves can induce many chemical reactions of different types. Two rather important examples that have been investigated systematically in the past decade in China are changes of minerals and reactions between carbon (diamond or graphite) and water under the conditions of high pressure and temperature produced by strong shock waves. 

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The first thing that we found was that defects had to be a minimum size to have any effect whatsoever. A vacancy, or even a divacancy, can be passed over by a shock wave without so much as a hiccup. However, beyond a certain size, a void (or vacancy cluster) can produce not only a warp in the shock front, but serious heating upon its collapse. Such an overheat can subsequently lead to initiation of chemical reaction originating at the void, even for a shock wave that would not have been strong enough to produce initiation in a perfect crystal (see Fig. 12). For materials that don t react chemically, such hotspots can still be nucleation sites for other shock-induced phenomena, such as plastic flow or polymorphic phase transformations. 

The initial decomposition chemistry involves unimolecular reactions. This was the conclusion of the first gas-phase kinetics study [84] and has been repeatedly confirmed by subsequent bulb and shock-tube experiments [85, 86]. That first study used shock heating to induce thermal decomposition [84], The data were interpreted in terms of simple C-N bond fission to give CH2 and N02. A more extensive and definitive shock-tube study was reported by Zhang and Bauer in 1997 [85]. Zhang and Bauer presented a detailed kinetics model based on 99 chemical reactions that reproduced their own data and that of other shock-tube experiments [84, 86]. An interesting conclusion is that about 40% of the nitromethane is lost in secondary reactions. 

Although propofol is generally said to be a remarkably safe dmg, 14 patients were reported to have life-threatening reactions within a few minutes of the administration of propofol, numerous other anaphylactic-like reactions have been reported, and other occasionally observed hypersensitivity reactions include bronchospasm, angioedema, urticaria, and erythematous rash. The overall incidence of anaphylaxis induced by propofol in France is about 1 % and 0.65 % in the Australian survey (Table 7.1). Another survey estimated that 1.2 % of cases of perioperative anaphylactic shock were attributable to propofol. Risk factors for a reaction are said to be a history of previous dmg allergy and the use with atracu-rium, the latter because of possibly enhanced histamine release. 

When bacteria or almost any organism are exposed to high temperatures, the synthesis of a set of HSPs encoded by heat shock genes is rapidly and transiently induced this reaction has been designated as the heat shock response. Later, it was foimd that most heat shock genes are not only induced by heat, but by many other stress regimens (Table 1). The stress factors have been classified into three groups physicochemical factors, metabolically harmful substances and complex metaboHc processes. Therefore, the heat shock is often called the stress shock to comply with these observations. 

In the literature we can now find several papers which establish a widely accepted scenario of the benefits and effects of an ultrasound field in an electrochemical process [13-15]. Most of this work has been focused on low frequency and high power ultrasound fields. Its propagation in a fluid such as water is quite complex, where the acoustic streaming and especially the cavitation are the two most important phenomena. In addition, other effects derived from the cavitation such as microjetting and shock waves have been related with other benefits reported for this coupling. For example, shock waves induced in the liquid cause not only an enhanced convective movement of material but also a possible surface damage. Micro jets of liquid, with speeds of up to 100 ms-1, result from the asymmetric collapse of cavitation bubbles at the solid surface [16] and contribute to the enhancement of the mass transport of material to the solid surface of the electrode. Therefore, depassivation [17], reaction mechanism modification [18], surface activation [19], adsorption phenomena decrease [20] and the mass transport enhancement [21] are effects derived from the presence of an ultrasound field on electrode processes. We have only listed the main phenomena referring to the reader to the specific reviews [22, 23] and reference therein. 

It is ironic that possibly the first animal model of relevance to immunotoxicology was reported by Portier and Richet in 1902 [45] in an attempt to induce tolerance to a sea anemone toxin, they accidentally produced a shock reaction in dogs. Since this was not the protective effect they had hoped to produce (phylaxis for protection in Greek), they named the reaction anaphylaxis [46], The irony, of course, is that this serious reaction, mediated by IgE in humans, has proven to be notoriously difficult to predict based on animal studies. This is no trivial issue, since anaphylaxis is a serious, life-threatening reaction associated with exposure to drugs, foods, cosmetic ingredients, and other exogenous substances [47],... 

Detonation, Water Plexiglos Induced Shock Wove Velocity in. Cook et al (Ref 2) applied the "aquarium technique in the exptl detn of the equation of state for water Lucire. The results for water are compared with similar results by other methods. Measurements of the peak pressures in the deton wave are presented for RDX, RDX/salt, TNT HBX-1. Peak pressures were found to be the CJ or deton pressures of the thermohydro-dynamic theory. There was no evidence whatever for the "spike of the Zel dovich-von Neumann model even though conditions were such that this spike would have been detected by the method employed if it were present, at lease in the large diam, nonideal expls of max reaction zone length Refs.T) C. Fauquignon, CR 251, 38 (I960) 2) M, A. Cook et al, JAppl... 

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