Cooling crystallization

Cool flames Cooling crystallizers Cooling towers... 

A stable crystalline form for chocolate depends primarily on the method used to cool the fat present in the Hquid chocolate. To avoid the grainy texture and poor color and appearance of improperly cooled chocolate, the chocolate must be tempered or cooled down so as to form cocoa butter seed crystals (31). This is usually accompHshed by cooling the warm (44—50°C) Hquid chocolate in a water jacketed tank, which has a slowly rotating scraper or mixer. As the chocolate cools, the fat begins to soHdify and form seed crystals. Cooling is continued to around 26—29°C, during which time the chocolate becomes more viscous. If not further processed quickly, the chocolate will become too thick to process. 

The energy-dispersive (EDX) solid state detector (SSD, Figs 4.6, 4.7) is made of lithium-drifted Si crystal (Si(Li)). Between a thin p-type and an n-type layer lies a high-resistivity Si crystal of centimeter dimensions. The front and end planes of the crystal are coated with Au and serve as electrodes. The crystal, cooled to 77 K by liquid nitrogen, represents a p-i-n diode (Fig. 4.7). An incident X-ray photon with... 

The maximum observed rotation for the 2-amino-2-methyl-1-propanol salt of levopimaric acid is [a] n —218°. Methanol and ethanol solutions give the same specific rotations, but methanol is the preferred solvent because the time required to effect solution in ethanol is longer. If pure levopimaric acid, m.p. 151-153°, [a] D —276° is desired, the salt with —210° rotation should be dissolved in 8 parts of boiling methanol, the solution concentrated to the point of incipient crystallization, cooled, and filtered. The yield in this recrystallization is about 70%. 

Peltonen, P. Lamberg, P. 1991. Chromian spinel in Svecofennian ultramafic intrusions compositional evolution during fractional crystallization, cooling, regional metamorphism and alteration. Geological Survey of Finland, Special Paper 2, 23-31. 

Preparation of a shock-cooled macromolecular crystal involves the rapid introduction of a loop-mounted sample into a cryogen. Introduction into the cryogen must be rapid in order to ensure that aqueous solvent within the crystal cools as a vitreous... 

When the reaction has terminated, filter off the precipitate and evaporate the solution in a bowl on a water bath until a film forms. What is the composition of the precipitated crystals Cool the solution to 0 °C, filter oH the crystals on a Buchner funnel, and dry them in a drying cabinet. Transfer the dry crystals into a previously weighed weighing bottle, weigh it, and calculate the yield in per cent. Write the equations of all the reactions. 

Five grams of basic carbonate and 25ml of propionic acid are used. The solution is evaporated at 130-140°C to crystallization, cooled, and the product is ground to a line powder. The latter is treated with 60ml of hot petroleum ether (b.p. 80-100°C), filtered, and the filtrate is cooled in ice overnight. The product is suction-filtered and dried in air. 

The conventional tartaric stabilization techniques applied in the wine industry are based on two opposite principles. One is aimed at heightening HT- and T2- precipitation by reducing wine temperature and leads to the so-called cold stabilization technique. To accelerate nucleation, wines are seeded with exogenous KHT crystals, cooled and kept at —4°C for 4-8 days... 

Crystallization of p- nitrotoluene. 8000 1. of crude molten p- nitrotoluene are charged into a tubular crystallizer, cooled to 39-40°C Mid this temperature is maintained for 24 hr. Then the whole is cooled to 18°C for 24 hr and the crystallizer is opened. The mother liquor is collected Mid the crystalline contents heated slowly to 50°C. The oil that was drawn off is collected sepMately and when it reaches... 

Royant, A., Edman, K., Ursby, T., Pebay-Peyroula, E., Landau, E. M., and Neutze, R. (2001a). Spectroscopic characterization of bacteriorhodopsin s L-intermediate in 3D crystals cooled to 170 K. Photochem. Photobiol. 74, 794-804. 

Nagahara H. and Ozawa K. (1986) Petrology of Yamato-791493, lodranite melting, crystallization, cooling history, and relationship to other meteorites. Mem. NIPR Spec. Issue 41, 181- 205. 

Solvent Fractionation. This process is the most expensive because of solvent loss, solvent recovery equipment, much lower temperature requirement, and stringent safety features. The process involves the use of solvents such as hexane or acetone. The oil is first dissolved in the solvent followed by cooling to the desired temperatures to obtain the desired crystals. Cooling is effected by brine if very low temperature is required. The miscella containing the partially crystallized oil and solvent is then filtered under vacuum suction in an enclosed drum filter. The olein miscella and stearin miscella are then separately distilled to remove the solvent and recover the fractions. Yield of olein is about 80%. The solvent process nowadays is only viable in the production of high value products such as cocoa butter equivalent or other specialty fats. 

The prepared emulsion is fed via a balance tank to a high-pressure pump, usually of a piston variety to a series of in-hne SSHEs. Once in the pasteurizer heating cylinders, the product is pasteurized and held prior to being subjected to precoohng and prepared for crystallization. Cooling, stabilizing, and texturizing of the emulsion are continuously undertaken within a series of A and B units. 

To 0.5 mL of the stock solution of semicarbazide hydrochloride, which contains 1 millimole of the reagent, add 1 millimole of the compound to be tested and enough methanol (1 mL) to produce a clear solution then add 10 drops of pyridine (a twofold excess) and warm the solution gently on the steam bath for a few minutes. Cool the solution slowly to room temperature. It may be necessary to scratch the inside of the test tube in order to induce crystallization. Cool the tube in ice, collect the product by suction filtration, and wash it with water followed by a small amount of cold methanol. Recrystallize the product from methanol, ethanol, or ethanol/ water. 

Hajdu, J., McLaughlin, P. J., Helliwell, J. R., Sheldon, J., and Thompson,. 4 W. Universal crystal cooling device for precession cameras, rotation camera and diffractometer. J. Appl. Cryst. 18, 528-532 (1985). 

Crystallization events in chocolate manufacture include tempering (pre-crystallization), cooling (bulk crystallization), and bloom (re-crystallization). These processes influence a number of important technological (economic) and sensorial attributes of chocolate (Table 1). Much attention has been focused on bloom formation and its influence on color and gloss, and for good reason, since a consumer may never even buy, let alone eat, a moldy-looking confection. However, we are less... 

Properties White crystals cool, saline taste somewhat hygroscopic. Sublimes at 350C, d 1.54. Soluble in water, glycerol slightly soluble in alcohol. 

Mol. formula C10H20O White crystals, cooling odor and taste. 

Scrapped surface Pipe within a pipe, with rotating blades scraping the inside walls of the inner pipe. Crystallization cooling applications. 

The temperature dependence of has been investigated in detail with myoglobin [202]. Diffraction studies at four temperatures between 220 and 300 K show the structure to be composed of a condensed core around the haem with displacements of the order of 0.04 A, which are temperature sensitive, and a semiliquid region towards the outside with mean square displacements 0.04-0.25 A, which are essentially temperature independent. The movements of the surface residues point to a possible pathway to the haem group. More detailed analysis at 80 K with crystals cooled by flash-freezing without the use of cryoprotectants showed a decrease in overall B from 14 A at 300 K to 5 A at 80 K [203]. Analysis of individual temperature factors showed that 46 out of the 153 residues in myoglobin had average B factors that extrapolated to zero at 0 K (i.e., arose from thermal vibrations alone). The temperature vibration of the remainder of the protein was consistent with the notion that conformational substrates could be frozen out at low temperatures. An additional 51 residues could be modelled with a linear dependence on temperature but with... 

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