Nucleation multicomponent

There are several further applications of the multicomponent theory Firstly, cilia have been treated [125, 49], such that there are two possible components attaching to the growth strip — cilia-nucleated molecules or molecules from... 

Atmospheric aerosols are multicomponent particles ranging from 0.001 to 10 pm in diameter. Particles are introduced into the atmosphere by combustion processes and a variety of other anthropogenic and natural sources. They evolve by gas-to-particle conversion and coagulation, are augmented due to the formation of fresh particles by nucleation, and are removed by deposition at the earth s surface and scavenging by airborne droplets. Atmospheric aerosols are the main cause of the visibility degradation accom-... 

The rate of crystal growth is determined by the degree of supersaturation, the rate of molecular diffusion to the crystal surface, and the time required for TAG molecules to fit into the growing crystal lattice (Mulder and Walstra, 1974 Walstra, 1987). Compared to nucleation, the driving force required for crystal growth is relatively low (Sato et al, 1989). However, in a multicomponent fat, the supersaturation for each TAG is small (Walstra, 1998). This fact, combined with competition between similar molecules for the same sites in a crystal lattice, means that milk fat crystallization is especially slow (Skoda and van den Tempel, 1967 Knoester et al, 1968 Grail and Hartel, 1992). 

Particle formation events from gaseous precursors are observed frequently almost everywhere in the troposphere, both in polluted cities and remote clean areas [4]. It is likely that different nucleation mechanisms are at work in different conditions, but no formation mechanism has been identified so far. It is, however, clear that particles are formed by nucleation of a multicomponent vapor mixture. Water vapor is the most abundant condensable gas in the atmosphere, but it can not form particles on its own homogeneous nucleation requires such a high supersaturation, that heterogeneous nucleation on omnipresent pre-existing particles always starts first and consumes the vapor. However, vapor that is un-... 

H. Vehkamaki, Classical Nucleation Theory in Multicomponent Systems, Springer, Berlin-Heidelberg, 2006. 

The extension of the CNT to homogeneous nucleation in atmospheric, essentially multicomponent, systems have faced significant problems due to difficulties in determining the activity coefficients, surface tension and density of binary and ternary solutions. The BHN and THN theories have been experiences a number of modifications and updates. At the present time, the updated quasi-steady state BHN model [16] and kinetic quasi-imary nucleation theory [24,66], and classical THN theory [25,33] and kinetic THN model constrained by the experimental data... 

Nucleation in the atmosphere is essentially multicomponent process. However, a commonly used classical approach incapable of the quantitative treatment of multicomponent systems due to (a) excessive sensitivity to poorly defined activity coefficients, density and surface tension of multicomponent solutions (b) strong dependence of nucleation rates on thermochemistry of initial growth steps where... 

Glass formation or the absence of crystallite nucleation and growth is also dependent on the confusion principle . This is an empirical observation which suggests that, in a multicomponent melt, several crystalline forms are in competition in the crystallization process the confused situation that results acts as a barrier to microcrystal growth and enhances the formation of the vitreous state. 

It is assumed that the crystallization behavior of milkfat is different between emulsion and bulk, and the lack of nucleation centers in the emulsion droplets may delay the nucleation, making less stable a form nucleated in the first. The occurrence of multiple forms of double-chain-length and triple-chain-length structures may be caused by segregated crystallization of multicomponent TAGs exhibiting complicated mixing behavior, but its details are open to fumre study. 

Oxtoby DW, Kashchiev D (1994) A general relation between the nucleation work and the size of the nucleus in multicomponent nucleation. J ChemPhys 100 7665-7671 Park PW, Ledford JS (1997) Characterization and CH4 oxidation activity of Cr/Al203 catalysts. Langmirir 13 2726-2730... 

For multicomponent particles, all components in a particle have the same velocity and thus Up can be found from Eq. (4.85). The only difference from the single-component case is that the terms for mass transfer and nucleation may be different for each component (e.g. just one component may change phases), in which case the right-hand side of Eq. (4.85) would include sums over the contributions for each component. 

The dependence of the capillary pressnre on the interfacial cnrvature leads to a difference between the chemical potentials of the components in small droplets (or bubbles) and in the large bulk phase. This effect is the driving force of phenomena like nucleation and Ostwald ripening (see Section 5.3.1.4 below). Let us consider the general case of a multicomponent two-phase system we denote the two phases by a and p. Let phase a be a liquid droplet of radius R. The two phases are supposed to coexist at equiUbrium. Then we can derive - ... 

Fat crystallization tends to be very slow, unless the supersaturation is high the latter can generally be realized. Nucleation is for the most part heterogeneous, where existing fat crystals are very effective catalytic impurities for other crystals. In a multicomponent fat, considerable secondary nucleation occurs, which results in quite small crystals. Slow recrystallization can lead to the formation of large crystals, and possibly to oil separation from the mass of crystals. 

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