Self-limiting reaction

Most patients treated for primary and secondary syphilis experience the Jarisch-Herxheimer reaction after treatment. This benign, self-limiting reaction is characterized by flulike symptoms, such as transient headache, fever, chills, malaise, arthralgia, myalgia, tachypnea, peripheral vasodilation, and aggravation of syphilitic lesions. The exact mechanism of the reaction is unknown, althongh proposed... 

Basically, microwave technology provides an alternative to conventional heating methods, with several important advantages penetrating radiation, controllable electric field distribution, rapid heating, selective heating of materials, and self-limiting reactions [19]. 

In dry air at room temperature this reaction is self-limiting, producing a highly impervious film of oxide ca 5 nm in thickness. The film provides both stabihty at ambient temperature and resistance to corrosion by seawater and other aqueous and chemical solutions. Thicker oxide films are formed at elevated temperatures and other conditions of exposure. Molten aluminum is also protected by an oxide film and oxidation of the Hquid proceeds very slowly in the absence of agitation. 

Many of the by-products of microbial metaboHsm, including organic acids and hydrogen sulfide, are corrosive. These materials can concentrate in the biofilm, causing accelerated metal attack. Corrosion tends to be self-limiting due to the buildup of corrosion reaction products. However, microbes can absorb some of these materials in their metaboHsm, thereby removing them from the anodic or cathodic site. The removal of reaction products, termed depolari tion stimulates further corrosion. Figure 10 shows a typical result of microbial corrosion. The surface exhibits scattered areas of localized corrosion, unrelated to flow pattern. The corrosion appears to spread in a somewhat circular pattern from the site of initial colonization. 

Self-Discharge Processes. The shelf life of the lead—acid battery is limited by self-discharge reactions, first reported in 1882 (46), which proceed slowly at room temperature. High temperatures reduce shelf life significantly. The reactions which can occur are well defined (47) and self-discharge rates in lead—acid batteries having immobilized electrolyte (48) and limited acid volumes (49) have been measured. 

Flanumbility limits (or explosion limits) for a flammable gas define tlie concentration range of a gas-air ini. ture witliin wliich an ignition source can start a self-propagating reaction. Tlie minimmn and maximmn fuel concentrations in air tliat will produce a self-sustaining reaction mider given conditions are called tlie lower Jlammability limit (LFL) and tlie upper Jlammability limit (UFL). (The abbreviations LEL and UEL, for lower and upper explosivity limits, are sometimes used.) The flanunability limits are functions of... 

The presence of corrosion products is not always a negative event some small degree of surface corrosion of all steel heat exchanger surfaces is generally beneficial. Under the reducing conditions normally found on the surfaces of pre-boiler FW heaters, FW lines, and boiler surfaces, black magnetite naturally forms by the direct thermal reaction of water with steel. The development of this self-limited magnetite film is most desirable, and optimum formation is achieved at pH levels of 10.5 to 11.5. 

This oxidation reaction of steel is self-limited and takes place by the direct reaction of FW (or BW) with steel, which in effect is accomplished by the reduction of hydrogen ions supplied by the water. The reaction is shown here ... 

C, the rate of reaction tends to be self limiting at hydrogen pressures up to 10 torr. The hydriding technique is used to recover metallic plutonium residues clinging to the walls of ceramic crucibles, and can also be used to recover machining scrap if the feed is free of lubricants or oxides. Mulford and SturdyO4) have found the heat of formation for the reaction... 

Deposition temperature is 850°C and pressure is < 1 Torr. The reaction is self-limiting since it relies on the diffusion of Si through the silicide. 

Example 13.3 The conversion of a self-condensing reaction can be limited to give polymers with finite lengths. How does the polydispersity of these polymers compare with those in Example 13.2 where the reaction went to completion with imperfect stoichiometry Make the comparison at the same average chain length. 

A higher level of incorporation can be achieved by resubjecting the modified polymer to the reaction conditions, as seen in the conversion of sample 6 -> 7. A third exposure to the conditions, which involved the conversion of sample 7 -> 8, does not give higher incorporation, and in fact appears to result in a decrease. Thus the reaction appears to be self-limiting, and the existing fluoroalkanol or fluoroalkyl ether groups may act to quench the radical promoter, and inhibit further incorporation. 

This reaction scheme applies to the cases of a nuclear explosion, non-cyclic, and of increase in cell population and disease, which may appear to be expanding reaction patterns, but are also self-limiting (see Eigen in Further Reading). We also draw attention to autopoietic systems described by Bitbol and Luisi in Further Reading. 

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