Average free

The smaller cavities are distorted pentagon dodecahedra (distance of oxygen atoms to center varies between 3.77 and 3.95 A) their average free diameter is only about 5.0 A. The larger cavities are almost spherical the oxygen atoms lie at the vertices of hexadeca-hedra and their free diameter is 6.7 A. The distances have been calculated on the basis of a unit cell edge of 17.40 A as found for propane hydrate. 

Cohen and Turnbull [20,21] laid down the foundation for the free volume concept in modeling self-diffusion in simple van der Waals liquids. They considered that the volume in a liquid is composed of two parts, the actual volume occupied by the liquid molecules and the free volume surrounding these molecules opened up by thermal fluctuation. Increasing temperature increases only the free volume and not the occupied volume. The average free volume per molecule, vf, can be defined as... 

The sign of V(r) at any point in space depends on whether the nuclear contribution (positive) or the electronic (negative) dominates. For neutral, spherically-averaged free atoms, V(r) is positive everywhere, decreasing monotonically with radial distance from the nucleus [3, 4]. When atoms interact to form molecules, however, the concomitant polarization of their charge distributions (relatively minor but very important) results in the development of regions of negative potential. These occur primarily... 

Strips of a material 10 mm thick are dried under constant drying conditions from 28 per cent to 13 per cent moisture in 25 ks. If the equilibrium moisture content is 7 per cent, what is the time taken to dry 60 mm planks from 22 to 10 per cent moisture under the same conditions, assuming no loss from the edges All moisture contents are expressed on the wet basis. The relation between E, the ratio of the average free moisture content at time t to the initial free moisture content, and the parameter / is given by ... 

Figure 9 Properties of the attractive colloidal fluid investigated in Ref. 75 (a) self-diffusivity and (b) average free volume versus strength of the interparticle attraction (c) self-diffusivity versus average free volume for the hard-sphere fluid (open circles) and the attractive colloidal fluid (closed circles). Data compiled from Ref. 75.

The relation between E, the ratio of the average free moisture content at time t to the initial free moisture content, and the parameter J is given by ... 

The current model for Mg + transport is illustrated in Figure 8 and is believed to be controlled by a magnesium sensor consisting of two specific Mg + binding sites located on the outside of the funnel in the a a sandwich domain that spans the wiUow helices and /3-sheets ° . Studies of similar binding sites in other proteins indicates that these sites will probably have an affinity for Mg + that is slightly less than the average free concentration of Mg + in cells . When the concentration of Mg in the cell drops below... 

The experimental results confirm the idea that at the initial stage of the experiment, the reaction is under diffusion control. This process has a very low activation energy, and when combined with thermal disintegration of the coal at higher temperatures, it lowers the average free energy of activation for the reaction. 

The average free volume per particle is (fifree) = Vfree/N = k/0. Therefore, comparison of the average free volume to its definition from a probability distribution,... 

The evaluation of the thermodynamic properties of the optically active macromolecular systems starting from the temperature coefficient of rotation, is therefore very complicated however a preliminary attempt (69) to perform a calculation of this type was made by Luisi, by adoptingthe Volkenstein and Ptitsyn theory (759). It was thus shown that the difference in the average free energy between monomeric units included in spiraled sections of different screw sense (17) should be about 300—500 eal/mol for highly isotactic optically active poly-a-olefins. 

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