Small in situ

An interesting consequence of surfactant moving through the core more slowly than the brine with which it is injected, when the salinity of the formation brine is higher than the salinity of the chemical slug, is that the brine of the chemical slug in effect conducts a small in situ preflood. When that condition exists, the salinity of the formation brine has little effect on the amount of oil recovered by the chemical flood. 

The theoretical and experimental results of this study clearly point out that the magnitude of oscillations of the calibration curve of the PDPA can be minimized via the correct choice of optics and collection angle. For fine particles (<10 um). resolutions of up to +/- 0.3 um may be realized. This resolution should be adequate for many aerosol measurements The excellent agreement between the experiment and model point out the validity of the model for the prediction of the PDPA response. A small in-situ probe for process monitoring is also described. 

The experimental data and arguments by Trassatti [25] show that at the PZC, the water dipole contribution to the potential drop across the interface is relatively small, varying from about 0 V for An to about 0.2 V for In and Cd. For transition metals, values as high as 0.4 V are suggested. The basic idea of water clusters on the electrode surface dissociating as the electric field is increased has also been supported by in situ Fourier transfomr infrared (FTIR) studies [26], and this model also underlies more recent statistical mechanical studies [27]. 

Thioformamide is prepared in situ at 25 to 30°C. as described previously, and in the presence of magnesium carbonate (492. 512. 578). The mixture is then mildly heated on a water bath, and when temperature reaches 70°C, a-haloaldehyde is added in small quantities. At the end of this addition the reaction mixture is stirred for 2 hr at 100°C. Thiazoles were isolated in the usual manner by a double steam distillation. 

The only method that yields the 2-unsubstituted thiazoie derivatives directly involves the condensation of a-haloketones with thioformamide. As in the case of previously reported a-haloaldehydes, yields are better when more reactive bromoketones are used instead of a-chloroketones. Cyclization can be achieved by adding ketones dissolved in dioxane in small quantities to the thioformamide formed in situ at below 40°C. The temperature is kept below 70°C during the addition, and then the... 

Where there are large volumes of contaminated water under a small site, it is sometimes most convenient to treat the contaminant in a biological reactor at the surface. Considerable research has gone into reactor optimization for different situations and a variety of stirred reactors, fluidized-bed reactors, and trickling filters have been developed. Such reactors are usually much more efficient than in situ treatments, although correspondingly more expensive. 

Chlorine gas is usually used, but electrolysis of alkaline salt solutions in which chlorine is generated in situ is also possible and may become more important in the future. The final pH of solutions to be sold or stored is always adjusted above 11 to maximize stabiUty. The salt is usually not removed. However, when the starting solution contains more than 20.5% sodium hydroxide some salt precipitates as it is formed. This precipitate is removed by filtration to make 12—15% NaOCl solutions with about one-half of the normal amount of salt. Small amounts of such solutions are sold for special purposes. Solutions with practically no salt can be made by reaction of high purity hypochlorous acid with metal hydroxides. 

ButylatedPhenols and Cresols. Butylated phenols and cresols, used primarily as oxidation inhibitors and chain terrninators, are manufactured by direct alkylation of the phenol using a wide variety of conditions and acid catalysts, including sulfuric acid, -toluenesulfonic acid, and sulfonic acid ion-exchange resins (110,111). By use of a small amount of catalyst and short residence times, the first-formed, ortho-alkylated products can be made to predominate. Eor the preparation of the 2,6-substituted products, aluminum phenoxides generated in situ from the phenol being alkylated are used as catalyst. Reaction conditions are controlled to minimise formation of the thermodynamically favored 4-substituted products (see Alkylphenols). The most commonly used is -/ fZ-butylphenol [98-54-4] for manufacture of phenoHc resins. The tert-huty group leaves only two rather than three active sites for condensation with formaldehyde and thus modifies the characteristics of the resin. 

Self-baked carbon electrodes are those whose shapes are formed in situ (33). The carbonaceous mixture is placed into a hoUow tube-shaped metal casing. The upper end receives the unbaked mixture as a soHd block, small particles, or warm plastic paste. The casing contains inwardly-projecting longitudinal perforated fins that become surrounded by baked carbon as the casing is incrementally moved downward and through the contact plates. Casing and carbon are consumed in this furnace. 

Another exception to the rule of contaminated surfaces involves very small particles, generally referred to as nanoclusters. These are generally formed and the adhesion of the.se particles to substrates studied in situ, under ultrahigh vacuum conditions. Owing to the vacuum and the short existence of these particles prior to deposition, it is possible for chemistry to occur. 

The insecticide carbaryl can be produced by several routes, some of which do not use methyl isocyanate, or which generate only small quantities of this toxic material as an in-process intermediate (Kletz, 1991b). One company has developed a proprietary process for manufacture of carbamate insecticides which generates methyl isocyanate as an in-situ intermediate. Total methyl isocyanate inventory in the process is no more than 10 kilograms (Kharbanda and Stallworthy, 1988 Manzer, 1994). 

Pedersen reasoned that there must have been a small amount of catechol present which had not been protected properly. This must have led to the formation of 1 in situ... 

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