Crystal the role

Nakata M, Shao RF, Maclennan JE, Weissflog W, Clark NA (2006) Electric-field-induced chirality flipping in smectic liquid crystals the role of anisotropic viscosity. Phys Rev Lett 96 067802-1-067802-4... 

K. Saigo, H. Kimoto, H. Nohira, K. Yanagi, M. Hasegawa, Molecular recognition in the formation of conglomerate crystal the role of cinnamic acid in the conglomerate crystals of 1-phenylethylamine and l-(4-isopropylphenyl)ethylainine salts. Bull. Chem. Soc. Jap. 

The synthesis of processable precursors for Si-B-N-C ceramics became a goal of intensive investigations as soon as the outstanding thermal and mechanical properties of this system were reported [1,2]. The amorphous phase of Si-B-N-C ceramics can show excellent thermal stability up to 2000 °C without mass loss or crystallization. The role of boron is believed to be to increase the high-temperature stability and to prevent the crystallization and decomposition of silicon nitride above 1500 °C. Primarily, the atomic ratio and chemical environment of boron in Si-B-N-C precursors seem to affect the thermal behavior of resulting ceramic materials. 

V. Nikolakis, D.G. Vlacho, and M. Tsapatsis, Modeling of Zeolite Crystallization the Role of Gel Microstructure. Microporous Mesoporous Mater., 1998, 21, 337-346. 

G. Schweicher, G. Gbabode, F. Quist, O. Debever, N. Dumont, S. Sergeyev, Y.H. Geerts, Homeotropic and planar alignment of discotic liquid crystals the role of the columnar phase. Chem. Mater. 21, 5867-5874 (2009)... 

An enlargement of the experimental data range is obviously of interest also for a better understanding of basic phenomenon. Indeed, despite the large number of papers concerning polymer crystallization, the role of mesomorphic phase in the formation of the crystalline structures is not completely... 

There are limitations to this model, however. Notably, these equations assume that the colloid surfaces are ideal—absolutely smooth and flat, completely homogeneous, and isotropic. In reality, surfaces are rather rough and chemically heterogeneous [54]. Such surfaces are difficult to achieve the only representative surfaces are carefully cleaved mica and perfect crystals. The role of surface roughness is discussed later. 

Two molecules of vitamin A are formed from one molecule of -carotene. Vitamin A crystallizes in pale yellow needles m.p. 64 C. It is optically inactive. It is unstable in solution when heated in air, but comparatively stable without aeration. Vitamin A is manufactured by extraction from fish-liver oils and by synthesis from / -ionone. The role of vitamin A in vision seems to be different from its systemic function. See also relincne and rhodopsin. 

Stem layer adsorption was involved in the discussion of the effect of ions on f potentials (Section V-6), electrocapillary behavior (Section V-7), and electrode potentials (Section V-8) and enters into the effect of electrolytes on charged monolayers (Section XV-6). More speciflcally, this type of behavior occurs in the adsorption of electrolytes by ionic crystals. A large amount of wotk of this type has been done, partly because of the importance of such effects on the purity of precipitates of analytical interest and partly because of the role of such adsorption in coagulation and other colloid chemical processes. Early studies include those by Weiser [157], by Paneth, Hahn, and Fajans [158], and by Kolthoff and co-workers [159], A recent calorimetric study of proton adsorption by Lyklema and co-workers [160] supports a new thermodynamic analysis of double-layer formation. A recent example of this is found in a study... 

Unlike melting and the solid-solid phase transitions discussed in the next section, these phase changes are not reversible processes they occur because the crystal stmcture of the nanocrystal is metastable. For example, titania made in the nanophase always adopts the anatase stmcture. At higher temperatures the material spontaneously transfonns to the mtile bulk stable phase [211, 212 and 213]. The role of grain size in these metastable-stable transitions is not well established the issue is complicated by the fact that the transition is accompanied by grain growth which clouds the inteiyDretation of size-dependent data [214, 215 and 216]. In situ TEM studies, however, indicate that the surface chemistry of the nanocrystals play a cmcial role in the transition temperatures [217, 218]. 

To develop a more quantitative relationship between particle size and T j, suppose we consider the melting behavior of the cylindrical crystal sketched in Fig. 4.4. Of particular interest in this model is the role played by surface effects. The illustration is used to define a model and should not be taken too literally, especially with respect to the following points ... 

By changing the role of the piezoelecttic crystal from regulating drop formation to propelling drops, the need for high pressure ink-pumping systems, drop charging and deflection systems, and waste ink plumbing systems were eliminated. 

Dehydrogenation is considered to occur on the corners, edges, and other crystal defect sites on the catalyst where surface vacancies aid in the formation of intermediate species capable of competing for hydrogen with ethylbenzene. The role of the potassium may be viewed as a carrier for the strongly basic hydroxide ion, which is thought to help convert highly aromatic by-products to carbon dioxide. 

The role of cerium in these lighting phosphors is not as the emitting atom but rather as the sensitizer. The initial step in the lighting process is the efficient absorption of the 254 nm emission Ce ", with broad absorption bands in the uv, is very suitable. This absorbed energy is then transferred to the sublattice within the crystalline phosphor eventually the activator ion is fed and emission results. Cerium, as a sensitizer ion, is compatible in crystal lattices with other lanthanide ions, such as Eu and Tb, the usual activator atoms. 

Correlations of nucleation rates with crystallizer variables have been developed for a variety of systems. Although the correlations are empirical, a mechanistic hypothesis regarding nucleation can be helpful in selecting operating variables for inclusion in the model. Two examples are (/) the effect of slurry circulation rate on nucleation has been used to develop a correlation for nucleation rate based on the tip speed of the impeller (16) and (2) the scaleup of nucleation kinetics for sodium chloride crystalliza tion provided an analysis of the role of mixing and mixer characteristics in contact nucleation (17). Pubhshed kinetic correlations have been reviewed through about 1979 (18). In a later section on population balances, simple power-law expressions are used to correlate nucleation rate data and describe the effect of nucleation on crystal size distribution. 

The early understanding of the geometry and dynamics of dislocations, as well as a detailed discussion of the role of vacancies in diffusion, is to be found in one of the early classics on crystal defects, a hard-to-find book entitled Imperfections in Nearly Perfect Crystals, based on a symposium held in the USA in 1950 (Shockley et al. 1952). Since in 1950, experimental evidence of dislocations was as yet very sparse, more emphasis was placed on a close study of slip lines (W.T. Read, Jr.,... 

The role of non-crystallizing soft segments in urethane adhesives... 

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