Explicator

OPES (Optimized Potentials for Liquid Simulations) is based on a force field developed by the research group of Bill Jorgensen now at Yale University and previously at Purdue University. Like AMBER, the OPLS force field is designed for calculations on proteins and nucleic acids. It introduces nonbonded interaction parameters that have been carefully developed from extensive Monte Carlo liquid simulations of small molecules. These nonbonded interactions have been added to the bonding interactions of AMBERto produce anew force field that is expected to be better than AMBER at describing simulations where the solvent is explic-... 

The rather low value obtained with the copper phthalocyanine, a low-energy solid (line (v)), is probably explicable by some reversible capillary condensation in the crevices of the aggregate, the effect of which would be to increase the uptake at a given relative pressure the plausibility of this explanation is supported by the fact that very low values of s, 1-47-1-77, were obtained with certain other phthalocyanines known to be meso-porous (cf. Chapter 3). 

Melt viscosity is a function of 7 - 7g, and a major cause of the difference between the viscosity of poly(methyl methacrylate) at its processing temperature (where 7 - 7g = 100°C approx.) and the viscosity of polyethylene at its processing temperature (where 7 - 7g = 200°C approx.) is explicable by the above relationship. 

In Fig. 9.1, orbitals below the dashed reference line are bonding orbitals when they are filled, the molecule is stabilized. The orbitals that fall on the reference line are nonbonding placing electrons in these orbitals has no effect on the total bonding energy of the molecule. The orbitals above the reference line are antibonding the presence of electrons in these orbitals destabilizes the molecule. The dramatic difference in properties of cyclobutadiene (extremely unstable) and benzene (very stable) is explicable in terms of... 

The immediate product of opening of the a-epoxide (160) is the chlorohydrin (161) which slowly eliminates to give the olefin. In contrast, the epimeric chlorohydrin (165) formed from the jS-epoxide (164) eliminates spontaneously to give the same product (162). This difference is explicable by the known enolization preferences of 5oc- and 5/3-3-ketones. 

These Br nsted-type plots often seem to be scatter diagrams until the points are collated into groups related by specific structural features. Thus, p-nitrophenyl acetate gives four separate, but parallel, lines for reactions with pyridines, anilines, imidazoles, and oxygen nucleophiles.Figure 7-4 shows such a plot for the reaction of trans-cmmm c anhydride with primary and secondary aliphatic amines to give substituted cinnamamides.All of the primary amines without substituents on the a carbon (R-CHi-NHi) fall on a line of slope 0.62 cyclopentylamine also lies on this line. If this line is characteristic of normal behavior, most of the deviations become qualitatively explicable. The line drawn through the secondary amines (slope 1.98) connects amines with the structure R-CHi-NH-CHi-R. The different steric requirements in the acylation reaction and in the model process... 

One way to do so is to look at the normal mode corresponding to the imaginary frequency and determine whether the displacements that compose it tend to lead in the directions of the structures that you think the transition structure connects. The symmetry of the normal mode is also relevant in some cases (see the following example). Animating the vibrations with a chemical visualization package is often very useful. Another, more accurate way to determine what reactants and products the transition structure coimects is to perform an IRC calculation to follow the reaction path and thereby determine the reactants and products explicity this technique is discussed in Chapter 8. 

Although the reaction has the overall stoichiometry of a dehydration it is more complex than this and involves a mutual redox reaction between N and N. This is at once explicable in terms of the volt-equivalent diagram in Fig. 11.9 which also interprets why NO and N2 are formed simultaneously as byproducts. It is probable that the mechanism involves dissociation of NH4NO3 into NH3 and HNO3, followed by autoprotolysis of HNO3 to give N02, which is the key intermediate ... 

The measured emfs of concentration cells of mercury(I) salts are only explicable on the assumption that a 2-electron transfer is involved. This would not be the case if Hg+ were involved [E = (2.303RT/nF) logai/a2 where n = 2 for Hg2 + and n = 1 for Hg+]. 

The more interesting situation arises in quinones which possess two dissimilar substituents. The site of initial carbon-to-carbon condensation is explicable in terms of the relative electronic effects. Thus condensation of 2-chloro-5-methylbenzoquinone (19) with t-butyl 3-aminocrotonate (20) in hot acetic acid furnished the 4-chloro-7-methylindole (21) in 51% yield. ... 

Erkennungs-marke, /. identiheation mark, -zeichen, n. characteristic, distinctive mark diagnostic symptom, erklarbar, a. explainable, explicable, erklaren, t.i. explain, illustrate declare, p.n-nounec. — t.r. explain grow clear, erklarlich, a. evident, obvious, apparent. Erkiiinmg, /. explanation, illustration dediara-tion. 

Given this explication of prediction, the general message we endorse could equally well be formulated by reserving the term accommodation for cases of what we have been calling accommodation, as by insisting that all predictions, if suc-... 

PdF2 is that rare substance, a paramagnetic palladium compound, explicable in terms of (distorted) octahedral coordination of palladium with octahedra sharing corners [15], It exists in two forms, both having /zeff 2.0 /xB, rather below the spin only value for two unpaired electrons. Bond lengths are Pd-F 2.172 A (two) and 2.143 A (four) in the tetragonal form (rutile structure). 

Complexes of O-donors are relatively rare, explicable by the soft nature of the divalent ions. A telling indication is that sulphoxide ligands will only bind through O if steric effects make S-bonding impractical. The most important complexes are diketonates and carboxylates (for the aqua ions see section 3.5). 

Features (2) and (3) are explicable in terms of the Dewar-Chatt-Duncanson model for bonding in alkene complexes (Figure 3.63), which involves... 

MMA polymerization is one of the most studied systems and was thought to be explicable, within experimental error, in terms of Bemoullian statistics. Moad et ai.jb have made precise measurements of the configurational sequence distribution for PMMA prepared from 13C-labeled monomer. It is clear that... 

Thus the x-ray data do not decide between this structure and a truly plane structure. Evidence from another source is at hand, however. A plane C03= or N03 ion should show three characteristic fundamental vibrational frequencies. These have been observed as reflection maxima in the infra-red region. But two of the maxima, at 7 m and 14m, are double,27 and this doubling, which is not explicable with a plane configuration, is just that required by a pyramidal structure, the separation of the components giving the frequency of inversion of the pyramid.28... 

Table II. It is seen that the agreement between calculated and observed intensities is almost complete the existent discrepancies are generally explicable as resulting from small errors in the parameter values (within the limits 0.005) or from errors in the assumed Incurves, for which an accuracy greater than dr 20% is not claimed.

These conditions suffice to determine the possible values of m and n3. As was shown by Pauli, they are compatible with the experimental evidence, and explain many previously difficultly explicable facts involving the exclusion of certain quantum states.f... 

In severe neonatal nemaline myopathy virtually every muscle fiber shows multiple rods and all muscle fiber types are affected. However in juvenile cases, two different patterns of fiber type involvement are seen. In one there is a clear size difference between type 1 fibers, which are abnormally small (hypotrophic or atrophic) and which contain numerous nemaline rods, and type 2 fibers, which are either of normal diameter or hypertrophic and contain few, if any, nemaline rods. Other patients show a gross predominance of type 1 muscle fibers, again with rods virtually confined to this fiber type. These findings may be explicable in terms of the involvement of isoforms of a-actinin specific to slow and fast muscle fiber types. 

Benzodiazepines do not induce their own metabolism, and thete is no evidence for the development of pharmacokinetic toletance (Gteenblatt and Shader 1986). The behavioral tolerance seen with chronic dosing is explicable entirely on the basis of pharmacodynamic tolerance (as described earlier in the overview of neuropharmacology). 

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