Leave-behind control

By using the above-mentioned functions, SFL can describe parallel control architecture (i.e., leave-behind control, parallel control, and pipeline control), as shown in Fig. 3.3. 

Selenium and precious metals can be removed selectively from the chlorination Hquor by reduction with sulfur dioxide. However, conditions of acidity, temperature, and a rate of reduction must be carefliUy controlled to avoid the formation of selenium monochloride, which reacts with elemental selenium already generated to form a tar-like substance. This tar gradually hardens to form an intractable mass which must be chipped from the reactor. Under proper conditions of precipitation, a selenium/precious metals product substantially free of other impurities can be obtained. Selenium can be recovered in a pure state by vacuum distillation, leaving behind a precious metals residue. 

The authors proposed the following picture of the silylene anion-radical formation. Treatment of the starting material by the naphthalene anion-radical salt with lithium or sodium (the metals are denoted here as M) results in two-electron reduction of >Si=Si< bond with the formation of >SiM—MSi< intermediate. The existence of this intermediate was experimentally proven. The crown ether removes the alkali cation, leaving behind the >Si - Si< counterpart. This sharply increases electrostatic repulsion within the silicon-silicon bond and generates the driving force for its dissociation. In a control experiment, with the alkali cation inserted into the crown ether, >Si — Si< species does dissociate into two [>Si ] particles. 

The agglomeration process is a dynamic process where a droplet is created by a two-fluid nozzle, and deposited on the randomly fluidized particle. The binder solvent evaporates, leaving behind the binder. Before all of the solvent is evaporated, other randomized particles form bonds on the wet site. This process is repeated numerous times to produce desired agglomerated product. There are number of process variables that control the agglomeration. Process variables most important to consider are listed as follows ... 

Note The purpose of smooth or controlled blasting is to produce an excavation contour, while leaving behind an intact, fissure-free formation. This is done by the use of diminished-strength expl charges, using numerous boreholes, driven exactly in parallel Ref R. Meyer, Explosives , Verlag Chemie, NY (1977), 239 314... 

Although with the selective removal proecdurc the active component and the support are usually verv intimately mixed, it is difficult to control the porous structure and/or the mechanical strength ol the result ing eatalyst bodies Nonetheless the procedure is difficult to beat for the production ol highly loaded supports The most well known example of selective removal, the preparation of Raney metals, where alu minum is selectively removed, leaves behind almost exclusively the desired active metal... 

If racemic sec alcohols (e.g., butan-2-ol, 52) undergo partial acylation with an acid anhydride in the presence of an optically active amine, an enantiomer differentiation occurs in the example shown, the (S)-alcohol reacts preferentially forming but-2-yl acetate, 53, which is levorotatory, and leaving behind unchanged alcohol which has been optically enriched [68]. This is a process under kinetic control. For further examples of kinetic resolutions, see [69]. 

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