Principal fraction

Fig. 11. Simplified representation of the separation of petroleum into six principal fractions.

The precipitated oily base is taken up in a total of 100 parts by volume of benzene. The benzene layer, dried over potassium carbonate, is filtered and then evaporated under reduced pressure. The residue from the evaporation is distilled in a high vacuum after separating a preliminary distillate which passes over up to 228°C under a pressure of 0.92 mm Hg, the principal fraction, 2-methylmercapto-10-[2 -(N-methyl-piperidyl-2")-ethyl-1 ]-phenothiazine, which distills over at 228° to 232°C under the last-mentioned pressure, is collected. The analytically pure base has a BP of 230°C/0.02 mm Hg. 

Chemical reactions Polymerization of casein and whey proteins are due to some kind of chemical reactions. The different proteins as found in the supernatant of milk after precipitation at pH 4.6 are collectively called whey proteins. These globular proteins are more water soluble than caseins and are subject to heat dena-turation. Denaturation increases their water-binding capacity. The principal fractions are P-lactoglobulin, a-lactalbumin, bovine serum albumin (BSA), and immunoglobulins (Ig). 

Evaporation and Evaporative Fractionation of Water. Evaporation from standing water bodies is the principal fractionation mechanism in most hydrological systems. Evaporative isotopic enrichment is a function of numerous factors (e.g., temperature, salinity, and relative humidity) that cause considerable variation in the lsO/ ieO and D/H ratios of natural surface waters. Craig and Gordon (22) evaluated isotopic effects on precipitation and evaporation in the ocean-atmosphere system. Much of what was developed in that work is directly applicable to the freshwater systems discussed here. 

The aqueous layer is acidified, the crude Z-menthoxyacetic acid is extracted with a liberal amount of toluene, the extract is distilled to remove toluene and water, and the Z-menthoxyacetic acid is distilled under reduced pressure. The principal fraction, b.p. 160-170°/10 mm., is satisfactory for conversion to the chloride. The yield is 76-78%, based on the chloroacetic acid. The pure acid has b.p. 163-164 °/10 mm., m.p. 52-54°, and [ ]d — 91.5° (o = 2, 95% ethanol). 

The design in Table 1 is called the principal fraction of the 24 1 design, and the sign in the generator D = ABC is positive (that is, D = +ABC). Another one-half fraction could have been constructed by using D = —ABC. This design would have all of the levels in column I) of Table 5 reversed. The two one-half fractions can be concatenated to form the complete 24 factorial design. 

XIII gives a more detailed analysis of the principal fractions in terms of sulfur rank and thiol content. 

The pyrolytic "wet" tar-sirup can be readily separated into two principal fractions by water extraction. The water-insoluble fraction is derived from lignin while the water-soluble fraction is carbohydrate in origin. Analytical results indicate large amounts of low molecular weight ( 100) lactones and aldehydes, and a significant fraction of these are multifunctional in nature. Four major classes of chemicals can be differentiated,... 

High tannin content in hazelnut by-product extract (skin and hard shell) was reported by Contini et al. [ 100]. Total tannins represented the principal fraction of the phenolic substances of the extracts, containing nearly 60%-65% of the total phenol [100]. As a general rule, the highest amount of total tannins was detected in the extracts with the highest amount of total phenols. Hence, the high antioxidant activity in hazelnut by-product extracts maybe due to these polyphenolic compounds since they are expected to have powerful antioxidant activity [100]. 

This is illustrated by Fig. 25, where media with various final values of pH were used (from the left) 3.4, 3.6, 3.7, 3.8, 3.9, 4.0 and 4.2 it is apparent that the range 3.7-3.9 is satisfactory. Just as in the examinations of pepsinogen, we also added cathepsin to electrophoretic protein fractions, and here the same result was obtained, showing that albumin is the principal fraction subject to polarographically detectable cleavage. We believe that the explanation is the same as that valid for pepsinogen, as described in Section 11. 

For some purposes the principal fractions can be employed as such. For instance. Fraction I is a suitable starting material for the preparation of fibrin foam and film and Fraction V, after a single reprecipitation, as already described, can be dissolved in a solution containing a suitable stabilizing agent, such as the sodium salt of aceiyl-tryptophan at 0.04 M, to give a concentrated solution of high stability which has found extended clinical use. However for many purposes further subfractionation of the principal fractions is essential, in order to obtain separately the many important components they contain. 

Sometimes sequences of fractional factorial designs can be used to estimate effects. For example, suppose we have run the principal fraction of experiments of the 2 design with generator C = AB. At this point we are willing to assume that the two factor interactions are negligible. However, after running the principal fraction of experiments we may still be uncertain about the interactions. 

These values may, of course, he slightly exceeded when the oU is not a complete distillation. As it is very heavy and takes many days for the wood to he exhausted on distillation, it is not uncommon to find commercial specimens which in fact represent the principal fractions of the oil, when the optical rotation may sink to about - 11 . 

The principal fraction (No. 3) had the same boiling-point as cadinene. The other characters of the cadinene-fraction isolated from the oil were di6o 0-9261, [a]D -I- 60 40, wd2oo 1-51112. 

Four principal fractions were obtained 1) 1500 x g. pellet ... 

Water-soluble o-glucans appear to be synthesized by one of the two principal fractions of the D-glucosyl transferase isolated from S. mutans 6715 water-insoluble D-glucans are synthesized by the other fraction. ... 

Peanut protein consists of two principal fractions, arachin and conarachin. Arachin is a dissociation system, and its apparent physical chemical properties are dependent on the state of equilibrium existing between the associated and dissociated species. Although chemical treatments have been devised for stabilizing derived products, very little information is available on the chemical reactions of the proteins. 

Details of the process and results of low-temperature-low-saJt-ethanol fractionation have recently been reviewed at length by Edsall (82) and the relevant aspects will be recapitulated here only in brief outline. The method yields the following five principal fractions in pooled normal human plasma ... 

Hie use of polyacrylamide gel instead of starch for fractionation of histones enabled an even finer fractionation of total histone and its principal fractions to be carried out (Driedger... 

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