Yielding Homogeneous

The numerical values of the distribution coefficients X and D have been derived from experimental data for a large number of systems (e.g. (10, 11, 13). From the constancy of either X or D values it can be determined whether or not the system yielded homogeneous precipitates. In either case, the numerical value of X or D should be equal to ... 

Aldrin has been administered in vivo by injection into the posterior adductor muscle and by topical application to tissues (primarily gill). During the test period, animals have been left undisturbed in the ocean surf, confined in retrievable traps, or held in beakers at the study site and in the laboratory. Study periods have varied from 2 to 24 hours. Animals frozen and later homogenized and extracted yielded homogenates which contained aldrin and dieldrin and no other electron-capturing metabolites compared to controls. 

Differentiation has been based on the main products of the fermentation. Generally, fermentation does not yield homogeneous products. For example, butyric acid is practically always accompanied by other fatty acids, both lower and higher in the series, as well as by alcohols, especially butanol, and by lactic acid. It may be noted that, according to Kempner and Kubowitz, fermentation can be transformed into lactic acid fermentation if the fermentation is carried out in an atmosphere of carbon monoxide. 

Due to light scattering, crystalline polymers mostly yield turbid films.Their blends with other polymers are always demixed because polymers are not able to form mixed crystals. Consequently, crystallizable polymers only yield homogeneous blends above their melting point. As soon as crystallization sets in, the components will separate. 

Again, decomposition of urea in an acidic metal salt solution in the presence of preformed particles can yield homogeneous layers of variable thicknesses of metal basic carbonates on the core materials of different chemical composition. In order to obtain uniformly coated particles (rather than a mixture of the latter and of the independently precipitated coating material), a balance between the amount of the initial dispersed matter and the concentration of the reacting solutes must be optimized. 

The inhibition of SuSy by the divalent cations (fCi 15 aM), Zn (fC 25 aM), and Ni (fti 37 aM) was exploited for further purification of SuSyl by immobilized metal affinity chromatography (IMAC). A subsequent gel filtration yielded homogeneous SuSyl suitable for crystallization experiments [24]. The protein chemical characterization revealed a homotetrameric organization of the 93 kDa subunit. Our kinetic data for the cleavage reaction and preliminary immunoblot analysis for phosphoserine suggested that SuSyl may be phosphorylated in the yeast expression system [28]. 

Kinetics in Non-Polar Media. Polymerization of vinyl monomers in non-polar solvents, i.e., hydrocarbon media, has been almost entirely restricted to the organolithium systems (7), since the latter yield homogeneous solutions. In addition, there has been a particularly strong interest in the polymerization of the 1,3-dienes, e.g., isoprene and butadiene, because these systems lead to high 1,4 chain structures, which yield rubbery polymers. In the case of isoprene, especially, it is possible to actually obtain a polymer with more than 90% of the eis-1,4 chain structure (7, 8, 9), closely resembling the microstructure of the natural rubber molecule. 

Mixtures of chemically homogeneous copolymers yield homogeneous films at Apmma below 25. 

Note that immunohistochemical reactions do not always yield homogeneous results but are subject to variations from slide to slide and from case to case. Because tumors are heterogeneous, caution is warranted in assuming that a particular section of the tumor is representative of the whole tumor (see page 14 for discussion on tumor heterogeneity). 

Treatment of perhydro-4-azaazulene (3) with mercuric acetate produces a mixture of dehydro derivatives 31a and 31b, which, with acids, yields homogeneous salts of structure 32 (56JOC344). The enamine 34, which was obtained by the same route from 33, served as a model compound in a study of the synthesis of cephalotaxine (72JOC3691). A reaction with ethyl y-bromo-acetoacetate surprisingly yielded the quinolizidine 36, which was formed by rearrangement of the intermediate annellation product 35 (Scheme 3) Phthalimides 38 were obtained from a Baeyer-Villiger oxidation of 4-azaazulen-3-ones 37 (77JOC1093). 

Similar to normal catalyst synthesis whereby ion exchange methods can result in egg-shell structures, in the preparation of monolith catalysts the majority of the metal can be deposited at the entrance of the monolith. Egg-shell structures can be attractive for catalyst particles, but for monoliths, analogous uneven distributions of the active phase are a disaster. Fortunately, extensive literature is available describing ion-exchange procedures for conventional catalysts that yield homogeneous metal distributions. This literature can be used as a guide for preparing satisfactory monolithic catalysts. 

Symmetrically 3,6-disubstituted pyridazines yield homogeneous 4-substituted products, but if the substituents are different the formation of two different 4- and 5-substituted products is expected and was observed when ieri-butylmagnesium chloride was added to 3-methoxy-6-phenylpyridazine (58). The products were not separated, but the mixture was hydrolyzed with acid and the products were characterized as a-tert-butyl-3-phenyl-6-oxo-l,4,5,6-tetrahydropyridazine (62). The ratio of the isomeric adducts is approximately 2 1 and the preponderance... 

The addition of organometallics to substituted pyridazines was studied extensively.108-121 Symmetrically 3,6-disubstituted pyridazines yield homogeneous 4-substituted products, but if the substituents differ, the formation of distinct 4- and 5-substituted products is expected. 

A number of methods have been used in the synthesis of perovskites the choice of a particular one depends mostly on the expected use for these oxides. Obviously, no attention has been paid to textural characteristics of samples whose uses are based on their electric or magnetic properties. However, application of perovskites in the field of catalysis requires solids with a well-developed porous network. As the present review is concerned particularly with the surface and catalytic properties of perovskites, we will place special emphasis on preparation methods leading to a high surface volume ratio. Also, methods yielding homogeneous solids will be discussed because of the important effect that inhomogeneities may play in heterogeneous catalysis. 

Glucosylceramide can also be synthesized chemically (Brady et al., 1965 Stoffyn et al., 1971). It has the advantage of yielding homogeneous products with respect to fatty acid and sphingoid base but is, of course, more laborious. 

In the last thirty years there has been a permanent search for a synthesis procedure able to yield homogeneous, high-surface-area materials. Moreover, the best method should be economical for large-scale production. Setting aside the traditional solid reaction method (calcination of a mechanical mixture of fine powdered oxides) many preparation procedures have been reported in the patent and open literature. They all start with the preparation of suitable solutions containing the cations in the right proportion to obtain the desired mixed oxide. 

Optional Catalytic Reactor (for increased hydrogen yield) Homogeneous ... 

---