Disk-shaped particle

Amphocil comprises a colloidal dispersion of disk-shaped particles with a diameter of 122 nm and a... 

Onsager s potential also applies to oblate particles or disks of high aspect ratio, if the parameter Uq ts redefined as 47rvnematic phase, called a discotic nematic. 

Considering a ratio of about 2 between Spsd and Sbet (figure 6) and the same radius R of particles measured by each technique, the contribution of each particle to Sbet is 2 ttR which, in turn, represents the surface developed by disk-shaped particles (neglecting thickness). 

Nucleosome Disk-shaped particles that consist of a core of histone protein around which DNA is wrapped. They are a structural unit of chromatin. 

A. Nucleosomes are disk shaped particles that consist of a core of histone protein around which DNA is wrapped. A short linker region of DNA joins nucleosomes. The core of the nucleosomes is made up of two copies each of histones H2A, H2B, H3, and H4. These histone proteins have A-terminal tails that contain lysine residues that can be reversibly acetylated, affecting the electrostatic interaction of the DNA with the histones. Histone HI is not part of the nucleosomes core, therefore acetylation would likely not affect the protein-DNA interaction of the nucleosomes. 

Schematic models for the expanded structure of bile acid-phosphatidylcholine mixed micelles are shown in Fig. 2B. The original model was proposed by Small in 1967 (S36). In this model the mixed micelle consisted of a phospholipid bilayer disk surrounded on its perimeter by bile acid molecules, which were oriented with their hydrophilic surhices in contact with aqueous solvent and their hydrophobic sur ces interacting with the hydrocarbon chains of the phosphohpid molecules. This model has recently been revised, based on further studies of mixed micelles using quasi-elastic light scattering spectroscopy (M20). In a new model for the molecular structure of bile acid-phospholipid mixed micelles. Mazer et al. (M20) propose a mixed disk, in which bile acids are found not only on the perimeter of phospholipid bilayers, but also incorporated within their interior in high concentrations (Fig. 2B). The size of these mixed micelles was estimated to be as high as 200 to 400 A in radius in some solutions, and disk-shaped particles in this size range were observed by transmission electron microscopy (M20). Micellar aggregates similar in size and structure to those found in model bile solutions have been demonstrated in dog bile (M22).

All three dimensions need not be in the colloidal range fibers or needle-shaped particles in which only two dimensions are in this range and thin films or disk-shaped particles in which only one dimension is in this range may also be treated as colloidal (7). Nor must the units of a colloidal... 

The theory of Dukhin (1981) was generalised by Listovnichiy Dukhin (1986) where the effect of stabilisation is considered under arbitrary hydrodynamic flow conditions around a bubble and the effect of convective transfer of surfactant into the adsorption layer was taken into account. Numerical estimations of 0, were carried out and it was shown that the effect of the liquid interlayer stabilisation by a DAL decreases the flotation efficiency over a wide range of system parameters by more than an order of magnitude. Numerical estimations also point to the fact that the effects under consideration have a much smaller influence on flotation of spherical particles than of disk-shaped particles. 

In summary, the model systems discussed in this part were zero-shear suspensions of disk-shaped particles in Newtonian liquids, mica-filled polymeric composites, LCPs and colloidal suspensions. The TCP model offers a good understanding of the flow behavior of exfoliated CPNCs. In the case of intercalated systems similar behavior is expected but is complicated by stress-induced changes in the degree of the dispersion and aspect ratio, as well as other possible modifications, such as the thermal decomposition of intercalant. 

Similar phenomena were observed in sols of iron oxide or tungstic acid with pronounced disk-shaped particles optical observations show parallel orientation of the disks with a uniform spacing up to 8000 A... 

With a thin disk-shaped particle, the surface area will have a much greater influence than that of its mass. A disk-like particle will settle very much more slowly due to it experiencing a higher drag relative to its mass and thus may be undersized. 

Ferroelectric fluid phases have also been observed in simulations of disk-shaped particles with embedded dipole moments along the symmetry axis [ 147,148] (see Sect. 4) and in a dipolar hard sphere model carrying two parallel dipole moments displaced equally from the sphere centre [ 149]. In the latter model antiferroelectric arrangement of the particles is, however, equally preferred at sufficiently large separations (0.3a) of the two dipole moments. 

Figure 25 The dielectric constant and loss vs. frequency ealeulated by using different models for oblate (disk-shape) particle along the axis of rotation at different particle volume fraction marked in the graphs, a) Maxwell-Wagner-Sillars equation b) Botteber-Hsu equation c) Looyenga equation. Parameters are =2, 8p=8, S/m, Op=10 S/m. The particle volume...

As noted earlier, in the 1920s Taylor [38] experimentally verified Jeffery s [37] analysis for the motion of ellipsoids. There were subsequent studies by Taylor in the 1930s [39,40]. In the 1950s Mason and his coworkers [41 to 44] made extensive efforts to visualize anisotropic particle motions in dilute suspensions during flow of rigid rod- and disk-shaped particles. They observed a distribution of orbits. 

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