Secondary chemical processes

A fourth, often overlooked problem is most prominent in noble gas matrices which are notoriously poor heat sinks because only very low energy lattice phonons are available to accept molecular vibrational quanta. Hence, thermalization is very slow compared to solution, and the excess energy that may be imparted onto an incipient reactive intermediate in the process of its formation (e.g., from a precursor excited state) may therefore be dissipated in secondary chemical processes such as rearrangments or fragmentations, which may make it impossible to generate the primary reactive intermediate. Often, this problem can be alleviated by attaching alkyl groups that serve as internal heat sinks, but sometimes this is not acceptable for other reasons. 

The photoreceptor operates in a reversible and cyclic manner. After excitation and activation of the secondary chemical process, the photoreceptor relaxes to its original ground state configuration. This blocks the chemical transformation, which is switched off. 

In solvents of moderate-to-large dielectric constant, AG °n0nei can be neglected provided there are no quantum mechanical interactions and no secondary chemical processes thus,... 

Ans. Yes. After the initial production of ions and/or free radicals, secondary chemical processes occur in which ions, free electrons, or free radicals react with nearby molecules to yield a variety of products. 

It is natural that as long as there are substances in the system that inhibit free radicals at the ends of the torn chain molecules, dangerous secondary chemical processes do not develop. Only after the inhibitors have been consumed does a rapid process of chemical change of the polymer arise, leading to its decomposition. Hence, appreciable secondary chemical processes begin only at the end of the induction period. Con-... 

Thus, the concentration of the free macroradicals arising under mechanical influences depends on the intensity of the influences, while the possibility of the development of secondary chemical processes is determined by the inhibitor concentration. 

It is natural that the appearance of free macroradicals should give rise (since this is not prevented by inhibitors) to complex secondary chemical processes, which change the structure and properties of the polymer mass to be reprocessed. At the same time, it is evident that the introduction of various substances active with respect to free radicals into the polymer during its reprocessing can regulate these secondary processes and, consequently, the properties of the mass to be reprocessed. 

This very limited list does not include migrations, rhythms and many primary secretory processes initiated by a physical or chemical stimulus. Certain migrations are initiated by chemical stimuli. Rhythms of organisms may be initiated by physical changes but secondary chemical processes are definitely involved. Glandular secretions such as salivation and many others result from chemical odorant molecules or gustatory stimuli. 

S 111 fi 1 r-reco ve ry p lants Carbon-black plants (furnace process) Primary lead smelters Fuel-conversion plants Sintering plants Secondary metal-production plants Chemical-process plants ... 

Secondary recovery, infill drilling, various pumping techniques, and workover actions may still leave oil, sometimes the majority of the oil, in the reservoir. There are further applications of technology to extract the oil that can be utilized if the economics justifies them. These more elaborate procedures are called enhanced oil recovery. They fall into three general categories thermal recoveiy, chemical processes, and miscible methods. All involve injections of some substance into the reservoir. Thermal recovery methods inject steam or hot water m order to improve the mobility of the oil. They work best for heavy nils. In one version the production crew maintains steam or hot water injection continuously in order to displace the oil toward the production wells. In another version, called steam soak or huff and puff, the crew injects steam for a time into a production well and then lets it soak while the heat from the steam transfers to the resei voir. After a period of a week or more, the crew reopens the well and produces the heated oil. This sequence can be repeated as long as it is effective. 

Transformation of parent contaminants into secondary products may occur during the processes of atmospheric diffusion and transport as a result of physical, chemicjd, and photochemical processes (22). Chemical conversion within the atmosphere may also change the physico-chemical characteristics of contaminants, dramatically altering their atmospheric residence times and fates from those of the parent contaminants. The complex reactions within the atmosphere that are driven by chemical processes such as hydroxyl scavenging... 

In porous liquid-phase electrodes, all pores are hlled with liquid electrolyte (solution or melt). When part of the pores are gas hlled, the electrodes are called gas-liquid. When the electrode is nonconsumable and chemically inert, its pore structure will remain unchanged during operation (or change very slowly on account of secondary aging processes). The structure of an electrode that reacts changes continuously. 

There are a variety of process safety risks one needs to assess with chemical processes. In general, these risks will lead to an evaluation of the potential for the process to have precipitous changes in temperature and or pressure that lead to secondary events such as detonations, explosions, over pressurizations, fires, and so forth. The most cost-effective way of avoiding these sorts of risks is through the adoption of inherent safety principles. Inherent safety principles are very similar to and complementary to pollution prevention principles, where one attempts to use a hierarchy of approaches to avoid and/or reduce the risk of an adverse event. The reader is referred elsewhere to a more complete treatment of this important area of process design. ... 

Gamo, T. (1995) Wide variation of chemical characteristic of submarine hydrothermal fluids due to secondary modification processes after high temperature water-rock interaction, a review. In Sakai, H. and Nozaki, Y. (eds.), Biogeochemical Processes and Ocean Flux in the Western Pacific, Terra Sci. Publ., pp. 425-451. 

MECHANISMS OF SECONDARY REACTIONS. The primary processes involved in absorption of radiation in polymers lead to the expectation of free radical and ionic mechanisms for the secondary chemical reactions. Electron spin resonance (ESR) spectroscopy has proved extremely valuable for observation of free radical reactions in polymers, where various radicals are stabilized in the solid matrix at different temperatures. 

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