Density fluctuations, during

Figure 2.18. Schematic representation of the density fluctuations during the spinodal decomposition mechanism (SD, left) and the nucleation and growth (NG, right). Three stages are shown early, where in SD the wavelength is constant but the amplitude increases, intermediate, where both the wavelength and the amplitude change, and late, where the concentration amplitude is at maximum and the wavelength increases due to coarsening processes after [Hashimoto, 1986],...

Imai, M., Kaji, K. and Kanaya, T., Structural formation of polyethylene terephthalate) during the induction period of crystallization. 3. Evolution of density fluctuations to lamellar crystal, Macromolecules, 27, 7103-7108 (1994). 

During the friction measurement, a test tube containing a small piece of gel is placed in the same water bath and the appearance of the gel is continuously monitored. The decrease of the diameter of the free gel from the isochore diameter is less than 10% at the highest temperature of the present friction experiment. This observation confirms that the gel swelling or shrinking as a whole should not have a significant effect on the friction measurement. A slight opacity of the gel develops in the gel in the vicinity of the temperature at which the friction of the gel diminishes and is presumably due to the dynamic density fluctuations. 

The activation entropy correspond to the density fluctuations of the material during the relaxation process [122,163,165],... 

The restriction to dense hquids and, in some respects, to one-component systems deserves further comment. Such restrictions follow from the physical assumption here that thermal fluctuations in are negligible. If a one-component liquid is sufficiently dense, then variety in the structures that occur with reasonable frequency during the thermal motion will be limited. Since density fluctuations may be gauged with the compressibility dp/dfip j, see Eq. (2.24) p. 27, these approximations are expected to be better where the compressibility is (or more generally, susceptibilities are) smaller. The compressibility is likely to be smaller for the higher density fluid states. 

Models are constructed which suggest that these optical measurements can be used to determine the effective particle size distribution parameters, mean diameter and sigma. Assumptions include multilayer particle deposit, the lognormal distribution of the diameters of the spherical, opaque particles, and no sorting of size classes during particle deposition. The optical measurement include edge trace analysis to derive the contrast transfer function, and density fluctuation measurements to derive the Wiener spectrum. Algorithms to perform these derivations are outlined. 

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