Crystal initiators

One important factor influencing the solubility of rosin derivatives is its tendency to crystallize. Initially, a rosin product may appear to be soluble in a given solvent, but on standing, the rosin will crystallize out of soluble solution. This tendency of rosin to ciystallize can be overcome by derivatization, mainly esterification. 

In an ideal ionic crystal, all ions are held rigidly in the lattice sites, where they perform only thermal vibratory motion. Transfer of an ion between sites under the effect of electrostatic fields (migration) or concentration gradients (diffusion) is not possible in such a crystal. Initially, therefore, the phenomenon of ionic conduction in solid ionic crystals was not understood. 

Precrystallization Initial crystallization Initial heating Initial drying De-dusting ... 

Synthetic pathways (as of 1990-1995) Salt Crystallization (Initial synthetic route) Chromatographic resolution Synthesis from a chiral pool... 

In general, intracellular freezing induced with extracellular ice crystal initiates around -5°C and most freezable water freezes by the time the cells reach -20°C. Thus, freezing injury of the cells should be concentrated in this temperature region. On the other hand, water molecules cannot endure in a supercooled state under —40°C even if there is no seeding of ice crystals. This suggests that reduction of cell viability is restricted to temperatures above -40°C. The results shown in Figure 9, also support this conjecture. 

Heats of immersion in water have been determined for a number of outgassed porous crystals enriched by ion exchange in various cations (zeolites X, Y, A, chabazite, and synthetic ferrierite), and for clinoptilolite and mordenite in their Na-forms, decationated, and in various stages of de-alumination. Finally, heats of immersion were determined in NaX, NaY, NaA, and (Ca,Na) chabazite in which the crystals initially contained various known loadings of zeolitic water. From the results, the influence of the exchange cations upon integal heats of sorption of water, AH, and other derived heats have been evaluated and discussed. 

Shear-induced crystallization had a much greater effect in bulk systems than emulsified systems (Fig. 6) and resulted in an accelerated rate of crystallization. Prior to, and during, the initial stages of crystallization, intradroplet fat is protected from interdroplet crystallization by the spherical shape and pressure of the droplet and is not directly available to the shear field, i.e., no protruding crystals. This observation is consistent with microstructure work where limited destabilization was observed in droplets with no visible crystals. Initially, droplet interfaces in the PSCO system showed that the crystallized fat was not available at the surface, limiting the occurrence of crystal-induced flocculation and coalescence. Droplets remained stable until their interfaces were disturbed by the shear fleld or crystal interaction. 

Calcification mechanisms. The mechanisms of CaCOs deposition have not been clearly defined. Two major questions are involved first, the relation of the organic portion of the skeleton to the initiation and control of crystal growth and, second, the role of the symbiotic photosynthetic zooxanthellae, the algae which grow within the tissue of hermatypic corals (Chapman, 1974). Another persistent question has been the site of crystal initiation, whether it is entirely extracellular or whether it is partly intracellulfir as well (Muscatine, 1971). 

Properties Colorless to yellowish crystals. Initial mp 133C, bp 271C, d 1.14 (but these vary somewhat from sample to sample). Soluble in water, ether, and alcohol. 

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