Cavity distribution analysis

Both DPPC and DPhPC bilayers present high probabiUties of cavity formation near the slip plane between two leaflets of each bUayer. However, the three-dimensional cavity distributions in these bilayers differ significantly from each 

Temporal proton-wire (a transient hydrogen-bonded chain of water molecules) formahon through the lipid bilayer may be one of the most plausible explanations of abnormally high proton permeability [61, 62, 77] In this hypothesis, the proton is transferred through the hydrogen-bond network that the proton wire has formed. 

Slower dynamics of acyl chains and translational motion 

Reduced dynamics of small penetrants — lower permeability 

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In our study [4] of cavity size distribution a sphere of diameter D is prescribed on every atomic center, and the cavity is evaluated as the pocket of contiguous space unoccupied by any of these spheres. The exclusion diameter D has to be equated to the van der Waals diameter Dvdw of a CH2 unit for the evaluation of the total cavity volume. When diffusion of small gas molecules through polymers is of interest, the unoccupied space available for inclusion of the small molecule can be evaluated by setting D equal to Dp + Dydw> where Dp is the diameter of the small probe molecule. The results of the cavity volume analysis were therefore presented [4] as a function of the exclusion ameter D varying over a range of values. 

Fig. 10. Analysis of the atomic lattice images of the lead compound entering CNTs by capillary forces (a)detailed view of the high resolution image of the filling material, (b)tetragonal PbO atomic arrangement, note the layered structure and (c)tetragonal PbO observed in the [111] direction, note that the distribution of lead atoms follows the contrast pattern observable in (a), (d)bidimensional projection of the deduced PbO filling orientation inside CNTs as viewed in the tube axis direction, note that PbO layers are parallel to the cylindrical CNT cavity.

Recently, many experiments have been performed on the structure and dynamics of liquids in porous glasses [175-190]. These studies are difficult to interpret because of the inhomogeneity of the sample. Simulations of water in a cylindrical cavity inside a block of hydrophilic Vycor glass have recently been performed [24,191,192] to facilitate the analysis of experimental results. Water molecules interact with Vycor atoms, using an empirical potential model which consists of (12-6) Lennard-Jones and Coulomb interactions. All atoms in the Vycor block are immobile. For details see Ref. 191. We have simulated samples at room temperature, which are filled with water to between 19 and 96 percent of the maximum possible amount. Because of the hydrophilicity of the glass, water molecules cover the surface already in nearly empty pores no molecules are found in the pore center in this case, although the density distribution is rather wide. When the amount of water increases, the center of the pore fills. Only in the case of 96 percent filling, a continuous aqueous phase without a cavity in the center of the pore is observed. 

A detailed analysis of the distributions of conversion, temperature and velocities was carried out126 using a model, which included the fountain effect at the front of the stream. A comparison of the results was made for molds of different geometrical form (plane cavity, cylindrical and disk-like shapes) for the same temperature, average output and cross-sectional width of the mold. It was established that the distribution of the degree of conversion is qualitatively the same in all these cases (Fig. 4.55). 

The next crucial observation came from a thermodynamic study of the radiation which is emitted through an aperture in the wall of a heated and otherwise closed oven. Once more, it was the intensity distribution of the radiation emitted at different wavelengths that defied analysis. Presented in graphical form the observed distribution is Figure 2.5 The intensity dis- as shown in the Figure 2.5. The distribu-tribution of radiation trapped tion predicted by the laws of thermodynam-in a closed cavity. ics is shown as the Raleigh-Jeans curve. It... 

Through the analysis of adsorption isotherms and 129Xe NMR results of the co-adsorbed xenon, we have shown that the dispersal of benzene molecules depends on not only the cation distribution but also the amount of benzene adsorbate within the supercage of zeolite adsorbents. We have also demonstrated for the first time that this well known indirect technique has the capability not only to probe the macroscopic distribution of adsorbate molecule in zeolite cavities but also to provide dynamic information about the adsorbate at the microscopic level. Conventional H and 13C NMR which directly detect the adsorbate species, although providing complimentary results, are relatively less sensitive. 

It is also possible to prepare crystalline electrides in which a trapped electron acts in effect as the anion. The bnUc of the excess electron density in electrides resides in the X-ray empty cavities and in the intercoimecting chaimels. Stmctures of electri-dides [Li(2,l,l-crypt)]+ e [K(2,2,2-crypt)]+ e , [Rb(2,2,2-crypt)]+ e, [Cs(18-crown-6)2]+ e, [Cs(15-crown-5)2]" e and mixed-sandwich electride [Cs(18-crown-6)(15-crown-5)+e ]6 18-crown-6 are known. Silica-zeolites with pore diameters of vA have been used to prepare silica-based electrides. The potassium species contains weakly bound electron pairs which appear to be delocalized, whereas the cesium species have optical and magnetic properties indicative of electron locahzation in cavities with little interaction between the electrons or between them and the cation. The structural model of the stable cesium electride synthesized by intercalating cesium in zeohte ITQ-4 has been coirfirmed by the atomic pair distribution function (PDF) analysis. The synthetic methods, structures, spectroscopic properties, and magnetic behavior of some electrides have been reviewed. Theoretical study on structural and electronic properties of inorganic electrides has also been addressed recently. ... 

These qualitative statements are due to a simple graphical analysis of the cavity frequency distribution plot compared in Fig. 5.8. However, each cavity can be inspected and compared in detail. For example, the peak indicated by the arrow in Fig. 5.8 for 3A4 corresponds to the path-distance pairs reported in red color in Fig. 5.8(d). They end up far away from the heme in a subpocket region generated by the residues Leu 211 and Tyr 307. This subpocket is not present in the other CYPs and can be involved in a selective recognition of the substrate molecule. 

The flow of material into the mold cavity affects the way in which particles are distributed in the molded object. Analysis of parts indicates that particles flow by a... 

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