Control by additives

Water plays a primary role in corrosion of the metal walls of tanks and pipes (17), and increases the tendency for high speed pumps to produce wear particles and to exhibit shortened life. Formation of corrosion products can be controlled by addition of corrosion inhibitors, a mandatory additive in military fuels. However, corrosion inhibitors may also degrade other fuel properties and adversely affect ground filtration equipment. Thus they are not generally acceptable in commercial fuels where rigorous attention is given to clean and dry fuels upon aircraft fueling. 

Hydrates quickly, responsible for strength of cement in early stage setting time can be controlled by addition of gypsum Responsible for strength in all stages Responsible for final strength Little effect on physical properties... 

The synthesis in Scheme 13.37 also used a me,ro-3,4-dimethylglutaric acid as the starting material. Both the resolved aldehyde employed in Scheme 13.36 and a resolved half-amide were successfully used as intermediates. The configuration at C(2) and C(3) was controlled by addition of a butenylborane to an aldehyde (see Section 9.1.5). The boronate was used in enantiomerically pure form so that stereoselectivity was enhanced by double stereodifferentiation. The allylic additions carried out by the butenylboronates do not appear to have been quite as highly stereoselective as the aldol condensations used in Scheme 13.37, since a minor diastereoisomer was formed in the boronate addition reactions. 

The cell culture was carried out under the following conditions temperature 30 °C pH 7.0 controlled by the addition of 2 m KOH. The fermenter was aerated at 1 vvm via a submerged sparger and the agitation rate was controlled between 600 and 1000 rpm in order to maintain the dissolved oxygen concentration above 20 % air saturation. Foaming was controlled by addition of antifoam (Mazu DF 204, BASF). 

It is also interesting to note that the deleterious elements, with the exception of titanium, are elements that can be used to stabilize the iron-carbide phase. Titanium is also the only so-called deleterious element that appears to be somewhat controllable by additions of more magnesium, instead of one of the rare earths in common use (34). However, the use of rare earths... 

The above studies concerning rhodium deposition provide evidences of the crucial importance of surface chemistry on the final quality of the deposit. Purity can be controlled by addition of reactive components that assist the expected loss of ligands, which otherwise would leave contaminants such as halides, carbides or oxides on the deposits. 

Very acidic (high valent) cations will readily hydrolyse in aqueous solution, often even at low pH. These cations tend to form the polymeric metal oxide chains mentioned previously. This hydrolysis can be controlled by addition of boric acid (see Sec. 3.2.4.4) and forms the basis of a technique referred to as liquid phase deposition. This method can be reasonably included in the more general term of chemical solution deposition, and is treated, although not comprehensively, in this book. Ref 5 deals more thoroughly with this technique and describes many cases of SiOi as well as some examples of several other oxides not covered in this chapter. 

Ti-MCM-41 could be synthesized within 4 hours with a high crystallinity by the evaporation method and the pore size could be controlled by addition of TMB in this work. The TEM image of Ti-MCM-41 which was obtained in the presence of TMB indicates the regular and expanding pore arrangements. The purely siliceous MCM-41 sample was also synthesized and used to immobilize the chiral salen complexes as in Scheme 1, which was synthesized without addition of Ti source by the same method as adopted for Ti-MCM-41 using a C22TMAC1 surfactant in methanol solvent without addition of TMB. 

Lotka-Volterra model reveals different kind of autowave processes with the non-monotonous behaviour of the correlation functions accompanied by their great spatial gradients and rapid change in time. Due to this fact the space increment Ar time increment At was variable to ensure that the relative change of any variable in the kinetic equations does not exceed a given small value. The difference schemes described above were absolutely stable and a choice of coordinate and time mesh was controlled by additional calculations with reduced mesh. 

The transformation of the initial defective V0P04 is thus not a side effect but the central step enabling the active phase. The defect structure controlled by addition of promoters like Co, Ga, Fe and others will affect the partitioning between large crystalline material and still nanostructured VPO that is the reactive precursor to... 

It is reported that an industrial explosion was initiated by charging potassium hydroxide in place of potassium carbonate to the chloro-nitro compound in the sulfoxide [1], Dry potassium carbonate is a useful base for nucleophilic displacement of chlorine in such systems, reaction being controlled by addition of the nucleophile. The carbonate is not soluble in DMSO and possesses no significant nucleophilic activity itself. Hydroxides have, to create phenoxide salts as the first product. These are better nucleophiles than their progenitor, and also base-destabilised nitro compounds. Result heat and probable loss of control. As it nears its boiling point DMSO also becomes susceptible to exothermic breakdown, initially to methanethiol and formaldehyde. Methanethiolate is an even better nucleophile than a phenoxide and also a fairly proficient reducer of nitro-groups, while formaldehyde condenses with phenols under base catalysis in a reaction which has itself caused many an industrial runaway and explosion. There is thus a choice of routes to disaster. Industrial scale nucleophilic substitution on chloro-nitroaromatics has previously demonstrated considerable hazard in presence of water or hydroxide, even in solvents not themselves prone to exothermic decomposition [2],... 

Porous properties of this monolithic polymer were controlled by addition of ammonium sulfate. Micrographs shown in Fig. 6.6 clearly demonstrate the changes in... 

Chlorosulphonic acid (CSA), HS03C1, has also been used as an effective sulphonating agent. The effectiveness of chloride as a leaving group and the absence of water as a byproduct mean that chlorosulphonation can be run at stoichiometry close to 1 1 and with efficient conversion of the organic substrate. The reaction temperature can be controlled by addition rate of the CSA and some very good product colours can be achieved. The by-product of chlorosulphation is HC1, or NaCl after neutralisation. The salt level in the surfactant is typically < 0.5% and this would need to be accounted for in formulation since it could affect the viscosity. 

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