Static crystallization

One drawback of static crystallization is that crystal layer growth rates are very slow. In the Sulzer MWB process, growth rates are gready improved by allowing a film to dow down vertical tubes (83). 

PROABD MSC [melt static crystallization] A process for purifying /r-xylene by crystallization. Used in conjunction with MSTDP. Piloted in France from 1994 to 1996 and proposed for installation in India in 1997 and in Bulgaria in 1998. 

Sulzer A family of processes for purifying organic chemicals by melt-crystallization without using solvents. Two systems are in use static crystallization, and falling-film ciystalliza-tion. The latter is proprietary to Sulzer Chemtec, Switzerland. 

The multipole model reduces the crystal electron density to a number of parameters, which can be fitted to experimental structure factors. For CU2O, structure factors for the (531) and higher-order reflections out to (14,4,2) were taken from X-ray measurements. Weak (ooe) (with o for odd and e for even) and very weak (eeo) reflections were also taken from X-ray work. Fig. 6 shows a three-dimensional plot of the difference between the static crystal charge density obtained from the multipole fitting to... 

The EFG data from the multipole parameters are, in principle, for the static crystal while the spectroscopic data are affected by vibrations. There may therefore by a systematic difference between the two sets of values, which is evident for a number of hydrogen-bonded hydroxyl groups and water molecules studied by Tegenfeldt and Hermansson (1985), but is not apparent in the data in Table 8.3. The EFG values for H atoms in hydrogen-bonds is further discussed in chapter 12. 

It is easy to show by group-theoretical arguments that the mixing of the even and odd ionic states occurs only if the crystal field lacks a center of symmetry, that is, is not holohedral. The selection rules appropriate for ions in a static crystal field have been given by Hellwege (26). However,... 

A general model for electronic relaxation of the Gd3+ S = 7/2 ion in various complexes in solution was presented by Rast el al. [86]. Contrary to the usual assumption, the electronic relaxation in their model is not only due to the effects of the transient zero field splitting, but is also strongly influenced by the static crystal field effect which is modulated by the random Brownian rotation of the complex. Experimental peak-to-peak widths of three gadolinium complexes could be well interpreted as a function of temperature and frequency using three static and one transient crystal field parameters. Moreover, their interpretation of experimental data did not require the addition of any field independent contribution to the line width like the spin-rotation mechanism. 

Low-lying energy levels in static crystal field model 529... 

In considering the vibronic side-bands to be expected in the optical spectra when we augment the static crystal field model by including the electron-phonon interaction, we must know the frequencies and symmetries of the lattice phonons at various critical points in the phonon density of states. We shall be particularly interested in those critical points which occur at the symmetry points T, A and at the A line in the Brillouin zone. Using the method of factor group for crystals we have ... 

LOW-LYING ENERGY LEVELS IN STATIC CRYSTAL FIELD MODEL... 

It should be noted that NMR studies are performed on proteins in their native solution state. Since the protein molecules are moving around in solution, the NMR technique measures scalar quantities (torsion angles and interproton distances) this is fundamentally different from x-ray crystallography in which the static crystal lattice allows a vector image of the molecule to be obtained. Since NMR studies are performed on proteins in solution, the technique can be used to probe intricate details of the dynamics of the protein. 

The preceding sections highlighted the similarities and differences between the static crystal structure and the average solution structure of rhodopsin in the cytoplasmic domain. This section considers fluctuations in the structure of the cytoplasmic domain relative to the average. This is of interest, because dynamics sequences are often correlated with function, and that appears to be the case in rhodopsin. 

The other C, A modification is a disordered, poorly crystalline form, called proto-C,A, which was obtained metastably from simulated clinker liquids, either by rapid cooling or by static crystallization at low temperatures (BIO). It gave an XRD powder pattern with broadened peaks, corresponding to the systematically strong reflections of cubic CjA indexable on the subcell with a 0.39nm. Analytical electron microscopy of individual crystals showed it to be very high in substituents, one preparation, for example, having an Fe/Al ratio of 0.54 (H6). 

Analytical solutions for the band structure are possible under simplifying approximations. In the adiabatic approximation the electronic states are calculated for a static crystal lattice and the problem of the vibrations of the lattice is treated independently. Finally, the interaction between the electrons and the vibrations is introduced to combine these results. In discussing the electronic states we will assume a static lattice. Limiting the problem to a linear... 

Figure 14. Cooling profile analysis of polarized micrographs of 100% AMF collected during the static crystallization process at the cooling rates of 0.1°C/min, 1°C/min, and 5°C/min depecting the microscopic properties (A) Df and (B) Df, monitored against changing temperature.

Experimental Study and Computer Modeling of the Dynamic and Static Crystallization of Cocoa Butter... 

In the first part of this work, static, dynamic, and intermediate dynamic-static crystallization kinetics of cocoa butter measured under isothermal conditions are reported. The effect of shear rate and time is analyzed using a kinetics theory previously developed for polymers. In the second part, these isothermal experimental... 

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