Close contact ratio

Close intramolecular contacts (clashes). A rough measure has been proposed and implemented in the program CONCORD [4,11] - the close contact ratio (CCR). The CCR of a 3D stracture is defined as the ratio of the smallest nonbonded distance to the smallest acceptable value for this distance. Normally, structures with CCR>0.8 are acceptable. Some programs as CORINA [5] or CONCORD [4, 11] have fallback procedures for attempting to relax close contacts in structures with unacceptably low CCR. 

Percentage of structures with a close contact ratio of greater than 0.8. 

An x-ray geometry is considered to be reasonably well reproduced if the RMS deviation of the atomic positions RMSxfz is less than 0.3 A. A chain geometry is taken to be well reproduced if the RMS deviation of the torsion angles at rotatable bonds RMSTa is less than 15°. A 3D molecular model is considered to be free of nonbonded interactions if the close contact ratio CCR (the ratio of the smallest nonbonded distance to the smallest acceptable value for this distance) is greater than 0.8. 

The variations of contact ratio under various loads and velocities are shown in Fig. 35. For the surfaces with combined roughness of 17 nm in the static contact or at very low speed, the contact ratio is close to 1, and it decreases with the increasing speed. The contact ratio also increases with loads if speed is fixed. Under the lower load (0.185 GPa), the contact ratio becomes zero at the speed of... 

However, X-ray analysis of these salts reveals the overall ratio of the acceptor to donor to vary (depending on the counterion and halide) from 4 1 to 1 1 (Table 3), and they show halide anions in close contact with two to four acceptor moieties, as illustrated in Fig. 10. 

Morphology. Structural details were visualized by cryo-TEM. Figure 1A is a cryo-TEM image of a sample with an entrapped oligonucleotide-to-lipid ratio of 0.13 mg/mg. It confirms the coexistence of unilamellar liposomes with bi- and multilamellar liposomes. The membranes of the latter are in close contact. The inset of Figure 1A is an expanded view of a multilamellar... 

This indicates that a close contact of the carbanion with the counterion favours isotactic placements as well as short sequence length (corresponding to persistence ratios below 1). In the system Cs/THF the marked non-Bernoullian behaviour can be described by Markovian statistics rather than the Coleman-Fox model, i.e. the penultimate monomer unit influences the stereochemistry of the monomer addition (29). This effect can be interpreted by decreasing external solvation (III,IV) and increasing intramolecular solvation (I,II). 

In Avcothane and Biomer, the exact concentration of CH2 is not known. However, in a similar polyurethane made of 2 1 1 molar ratio of 2,4-toluene diisocyanate/ethylenediamine/polyether (mol wt 1000), our calculation shows that the actual depth can approach the predicted value if care is taken to insure close contact. Therefore, we would assume, for the sake of argument, that in Avcothane and Biomer our actual values approach the predicted values. 

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