Vicinal groups definition

By definition, members of this group have a vicinal arrangement of their electron-deficient centers. They may be conveniently considered according to their atom composition and the hybridization state of any carbon atoms involved. 

It has been pointed out321-324 that the two groups of solvents differ by some definite structural features. In particular, ED, 1,2-BD, and 1,3-BD possess vicinal OH groups that can form intramolecular hydrogen bonds. For these solvents, the ability of the organic molecule to interact with neighboring molecules is reduced. This results in the possibility of a different orientation at the interface because of different interactions of the OH groups with the Hg surface.323 The different molecular structure leads to different dipolar cooperative effects. As a result, the dependence of C on the bulk permittivity follows two different linear dependencies. 

One intriguing aspect of enzymatic catalysis in low water environments (this includes 85% dioxane where the water activity is substantially less than unity) is the effect of reaction pH. In aqueous solutions, the ionogenic functional groups of an enzyme respond to the pH of the solution. Definitive pH optima exist for all enzymes. In organic solvents, however, the lack of water as a bulk solvent makes pH an unmeasurable variable although there will be a small concentration of protons in the vicinity of... 

We can calculate the right-hand side of (22) using the definition of Hna (q) together with (17). In the vicinity of the intersection of interest it is appropriate to retain in (22) only the lowest-order terms in each of the Qk (k = 1, 2,.. ., 3N — 6). In addition, in order to explore the point group symmetry properties of ij/ (rel q0) and v /j(rel q0) it is desirable to choose for the Qk coordinates which display simple transformation properties under the operations of that group, such as normal mode coordinates [13,15] or, in some circumstances, symmetrized hyperspherical coordinates [12,16,17]. Such choices lead to simple point group symmetries for the / (rel q0) and (rel q0) and permit the identification of which. (q0) and q0) vanish due to symmetry [18]. 

According to a general definition, the Reformatsky reaction can be taken as subsuming all enolate formations by oxidative addition of a metal or a low-valent metal salt into a carbon-halogen bond activated by a vicinal carbonyl group, followed by reaction of the enolates thus formed with an appropriate electrophile [23]. The insertion of metallic zinc into a-halo esters is historically the first and still the most widely used form of this process although Zn may be beneficially replaced but other metals and reducing metal salts in certain cases. 

In general, enzymes exhibit maximum catalytic activity at a definite pH. This optimum pH is generally in the vicinity of pH 7 ( 1), although exceptions are well known. The dependence of the kinetic parameters of the fumarase reaction on pH is illustrated in Figs. 9-2 and 9-3. Several different possible effects of pH on the reaction must be distinguished. In the first place, many substrates may have ionizable groups and only one of the ionized forms of the substrate may be acted upon by the enzyme. Since substrate ionization constants can be determined quite easily and precisely,... 

Supposing that all the doses are committed to the population in the 50 km vicinity of a model reactor, the average annual per capita effective dose is 5 pSv for PWR and GCR types, 10 pSv for BWR and HWR types, and 2 pSv, 0.04 pSv for LWGR and FBR types, respectively. Due to the definition and the inappropriate use of the collective dose, these values are somewhat overestimated. This overestimation is well illustrated by the study carried out for European power reactors, where for instance for the 2004 effluents data the annual effective dose for the member of the critical group at 500 m from a PWR or BWR reactor is less then 1 pSv (EUROPEAN COMMISSION 2008). 

A more definite way to solve the issue was the use of affinity labeling for the cholinergic receptor. This method is based on the use of N-maleimido benzyl (or phenyl) trimethylammonium (i.e. MBTA or MPTA) which binds to the anionic site of the receptor and makes a covalent link with a reduced S-S group in its vicinity (Karlin and Cowburn, 1973). With this method and SDS gel electrophoresis... 

The derivative of the microscopic cross sections r is obtained from the definition of the thermal group (4.209) and depends, of course, on a detailed knowledge of the energy dependence of a in the vicinity of kT. Unless otherwise noted, we will assume in this treatment that (1) all absorption cross sections aa vary as 1/v in the thermal range and (2) scattering and transport cross sections a, and cross section is also /v [see (4.234)] therefore, in the case of the... 

Values of optical rotations from [a]n +38° to + 78 , and various ratios of sulfate to hexosamine content have been reported these ratios, however, are all in the vicinity of i. Various contents of sulfamate and JV-acetyl groups have also been observed, and it has become evident that one is dealing more with a family of substances, possessing varying degrees of N- and 0-s ilfation, than with a chemical entity. Since our knowledge of the chemical structure of the polysaccharide chain is still scant, it has not been possible to ascertain definitely the chemical identity between the various low sulfated heparans. 

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