Crystal change

Very unstable modifications, like the reddish, chlorine-free a-copper phthalocyanine, can be stabilized with amides or salts of copper phthalocyanine sulfonic acids (59—63). Mixture with other metal phthalocyanines, eg, tin, vanadium, aluminum, or magnesium, also inhibits crystallization change and poor performance in binders and prints (flocculation) due to the hydrophobic character of unsubstituted phthalocyanines. 

Symmetry, crystal, changes in, 759 Symmetry, magnetic point, determination of, 741... 

C14-0138. Phosphorus forms white crystals made up of P4 molecules. There are two forms of white crystalline phosphorus, called a and p. The difference between P4 a and P4 is determined by the way the P4 molecules pack together In the crystal lattice. The a form is always obtained when liquid phosphoras freezes. However, at temperatures below - 77 ° C, the P4 cj crystals change spontaneously to P4 ... 

The white crystals change to yellow powder upon grinding, presumably with loss of THF and possibly some AuCN formation. Thermal gravimetric analysis of [Au2(2,6-Me2Ph-form)2] 2Hg(CN)2 2THF showed the release of THF gradually at >120 °C followed by decomposition at >200 °C. The powder diffraction pattern of the yellow residue after heating above 265 °C showed a pattern typical of AuCN (IR 2236 cm ) as confirmed by comparison with the powder diffraction pattern of a sample of AuCN obtained from the Aldrich Chemical Co. 

The log(wBj,2+)i(WgQ2-)i values for the solutions of the previous investigators T = 25-100°C) and ob.serve d morphologies of barite in their experiments) are compared as. shown in Fig. 1.55. It shows that the morphology of barite crystals changes with an increase in the concentration product, from well-formed (rectangular,... 

Weaver and co-workers have carried out extensive smdies of CO electro-oxidation on Au single crystals [Chang et al., 1991 Edens et al., 1996]. Continuous oxidation of CO on Au starts at potentials where the formation of surface oxides or surface-bonded hydroxyl (OH) is not apparent from voltammetry. Weaver suggested the following mechanism ... 

Dependence of results from the prior-prejudice distribution. Non-uniform prior-prejudice distributions (NUP for short in what follows) were initially introduced by Jauch and Palmer by centering 3D Gaussian functions at the nuclear positions [29]. They found that the low-density regions of the crystal changed significantly upon introduction of the NUP, but the uneven distribution of errors persisted. 

Crosslinks are assigned to their most probable positions, which change as crystallization changes. 

Buffer substances or other salts should be used in the smallest possible concentration, since they may partially crystallize (changes of pH-value) and they will mostly reduce Tg. 

Concluding this brief survey of the effects of cosolvents and temperatures on noncovalent binding forces between proteins, we may assume that while the dielectric constant may play a role in the cryoprotection of protein crystals, changes in interaction forces may confer protection or in some cases be responsible for crystal destruction. However, we must bear in mind that hydrogen bonds and salt links involved in the regions of contact between proteins will be strengthened and/or stabilized at low temperatures within certain limits of pan values, which should aid in the cryoprotection of protein crystals. 

Liquid crystals are mainly used for decorative purposes in cosmetics. Cholesteric liquid crystals are particularly suitable because of their iridescent color effects, and find applications in nail varnish, eye shadow, and lipsticks. The structure of these thermotropic liquid crystals changes as a result of body temperature, resulting in the desired color effect. In recent times, such thermotropic cholesteric liquid crystals have been included in body care cosmetics, where they are dispersed in a hydrogel. Depending whether this dispersion requires stirring or a special spraying process, the iridescent liquid crystalline particles are distributed statistically in the gel (Estee Lau-... 

The penetration in the absence of absorption is governed by the extinction distance,. This is the depth at which the intensity drops by a factor 1/e in a perfect crystal, and also the depth at which the Bloch wave in the crystal changes phase by a factor 2. ... 

In the optical resolution of DL-threonine mixtures by batch preferential crystallization, changes of solution concentration and crystal purity were measured. The mechanism of nucleation of the un-seeded enantiomer was discussed to explain the purity decrease of the resolved crystals. From the observation of crystallization behavior of the seed crystals of L-threonine, it was concluded that the existence of the D-enantiomer on the surface of the seed caused the sudden nucleation when they grew to attain sufficient amounts. 

They both gave saturated concentration for a-form crystal. Changing the saturation temperature, similar experiments were performed. Instead of adding 5 gr. of a-form crystal, 1 gr. of a-form crystal and 1 gr. of 3-form crystal were used and another series of data were collected. 

Results and Discussion. Experimental results are shown In Figure 4. Circular marks In this figure show the data when a-form crystal Is added. It seems that a part of a-form crystal changes Into 3-form crystal In the saturated solution at 316.2K or 312.3K with elapse of time. Triangular marks show the data when mixed crystals (a-form/ 3-form 1/1) are added. It also seems that a part of a-form crystal changes Into 3-form crystal at 303K and that a part of 3-form crystal changes Into a-form crystal at 278.4K. 

As the shape of the needle-like hemihydrate crystals changes as they dissolve, it is necessary to convert to the crystal width as a measure of size. In terms of this measure, the dissolution rate is first order with undersaturation and shows only a small temperature effect (activation energy of 10 kJ/mol). 

Hemlhydrate crystals change shape as they dissolve, and It Is necessary to convert from a volume equivalent size to a crystal width. The dissolution rate. In terms of crystal width, shows a first order dependence on undersaturation and a low activation... 

Red monoclinic crystal changes into a black allotropic modification at 267°C density 3.50g/cm3 melts at 320°C boils at 565°C insoluble in water soluble in alkalies. 

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