Cooling clarity

Microemulsions or solubilized or transparent systems are very important ia the marketing of cosmetic products to enhance consumer appeal (32,41). As a rule, large quantities of hydrophilic surfactants are required to effect solubilization. Alternatively, a combination of a solvent and a surfactant can provide a practical solution. In modem clear mouthwash preparations, for example, the flavoring oils are solubilized in part by the solvent (alcohol) and in part by the surfactants. The nature of solubilized systems is not clear. Under normal circumstances, microemulsions are stable and form spontaneously. Formation of a microemulsion requires Httle or no agitation. Microemulsions may become cloudy on beating or cooling, but clarity at intermediate temperatures is restored automatically. 

The process of fermentation gives off heat, and the tanks may need to be cooled with chilled water coils, with jackets, or by cooling the cellar in which the tanks are located. When fermentation is complete, many beers are now pasteurized, in the same manner as milk (see Section 17.1). The beer is then cooled to just above freezing, filtered and left to age . Before final bottling, kegging or canning it will undergo a fine filtration to improve the clarity. 

The clarity of the final beverage is affected by small particles of tartrates and other substances which precipitate during storage. To obtain a product which will remain clear in storage, many wines and spirits are cooled by refrigeration to a temperature just above their freezing points and then fine-filtered. 

Both polyethylene terephthalate and polybutylene terephthalate exhibit partial crystallinity in the solid state. The molecular weight of the polymer and the time permitted for cooling define the degree of crystallinity of the polymer. Very slow cooling results in high crystallinity and opacity, while fast quenching creates low crystallinity, high clarity material. 

Fig. 9. The 3/Hn coupling constants versus temperature for different alanine residues in XAO peptide. The reversibility of 3/hn coupling constant versus temperature was checked by measurements with temperature increasing from 2° to 56°C (labeled as heating) or decreasing from 56° to 6°C (labeled as cooling). The errors are the same in heating and cooling measurements the error bars are shown only for heating measurements for clarity. The conditions were temperature from 2° to 56°C, concentration ca. 4 mM, in 30 mM sodium acetate buffer (pH = 4.6, 10% D20 ). From Shi et al. (2002). Proc. Natl. Acad. Sd. USA 99, 9190-9195, 2002 National Academy of Sciences, USA.

Figure 8.3-3 shows the CO2- and THF-make-ups, together with the heating and cooling powers, required to run the plant in each case studied. The power needed to pump fluids is not represented, for clarity. 

Polypropylene (PP) films were first produced by extrusion casting. Polymer is extruded through a slit or tubular die and quenched by cooling on chill rolls or in a water bath. Cast films can be sealed over a wide range of temperatures and do not shrink in a steam autoclave, Polymers with melt flow rates below 5 dg/min are usually used to maintain the stability of the extra date. Higher clarity films are produced using random copolymers. 

Both gravity and pressure types are widely used to remove suspended solids and improve the clarity of sources of raw water, cooling system makeup, and recirculating cooling water. Sometimes filters may also be installed following use of a chemical precipitation softening clarifier for the complete removal of precipitated sludge or secondary precipitates where the water is perceived to be unstable. 

Fig. 12 (a) Reduced temperature T — 7]SO/bp vs xcdSe phase diagram for CE8 + CdSe mixtures obtained from cooling runs by a.c. colorimetry. Ti-bpiii was found to be a weak function of x. (b) T — rIso/BP vs xcdse plot for CE6 + CdSe mixtures obtained from heating runs by adiabatic scanning calorimetry. For clarity the data in both diagrams are plotted vs the Ti-bpiii [428]. (Copyright 2010, The American Physical Society)... 

Medium is ready for use immediately upon cooling. It should be inspected for clarity prior to use. 

Fig. 3.9. Enhancement of transmission Raman signal using a standard dielectric band-pass filter (BF) placed within the laser beam into the proximity of sample. The Raman spectra are those of a standard paracetamol tablet measured with (with band-pass filter) and without (bare) the filter. The spectra are offset for clarity. The acquisition times were 1 s in both cases with a laser power of 250 mW (827 nm). The spectra were detected with an Ocean Optics spectrograph equipped with a detector array cooled to -15° C...

Polymer sheets are cooled without stretching by convected cold air (or an inert gas), by immersion into a fluid bath, or by passage over chilled rolls. Flat films are usually stretched and oriented uniaxially and cooled by either of the methods previously mentioned. Films are also cast and cooled on rolls for optimal clarity purposes. 

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