De-freezing

De-freezing Minimum temperature (dew point) to be reached before unwrapping or minimum storage time at room temperature before unwrapping logging of temperature history... 

The problem of maintaining the reactor equipment reliability under multiple freezing/de-freezing of lead-bismuth coolant was solved this successful solution was demonstrated at large-scale facilities and in the reactor installations of nuclear submarines [XIX-4],... 

Operability of the reactor primary circuit components under multiple freezing/de-freezing of the lead-bismuth coolant Optimized temperature-time curve of freezing/ de-freezi ng Proven by the results of R D, testing and demonstrations... 

The technologies for safe freezing / de-freezing of the molten salt coolant need to be developed and mastered. 

Riehie U and Hdchii M 1973 The theory and technique of high pressure freezing Freeze-Etching Technique and Appiications ed E L Benedetti and P Favard (Paris Societe Frangaise de Microscopie Eiectronique) pp 31-61... 

Sweetness is primarily a function of the levels of dextrose and maltose present and therefore is related to DE. Other properties that increase with increasing DE value are flavor enhancement, flavor transfer, freezing-point depression, and osmotic pressure. Properties that increase with decreasing DE value are bodying contribution, cohesiveness, foam stabilization, and prevention of sugar crystallization. Com symp functional properties have been described in detail (52). 

Some typical moulding data for a range of plastics are given in Table 5.1. Note that the de-moulding temperature will be generally about 30°C below the Freeze-off temperature in order to ensure that the moulding is sufficiently solid for handling. 

The first studies leading to the deracemization of VANOL 93 and VAPOL 94 were carried out with 1.4 equiv. of copper chloride and 2.8 equiv. of (-)-sparteine 1 in a mixture of methanol and methylene chloride (1 3.4) de-oxygenated by an argon purge, which gave a 64% yield of (S)-VAPOL with 99% ee, and a 77% yield of (S)-VANOL with 99% ee. However, in the last case, the co-solvent was deoxygenated via a freeze-thaw method. 

ANCos B DE, GONZALES E M and CANO M p (2000) Ellagic acid, vitamin C, and total phenolic contents and radical scavenging capacity affected by freezing and frozen storage in raspberry fruit , J Agric Food Chem, 48 (10) 4565-70. 

Figure 1 indicates that pectin methyltransferase (PMT) activity from freeze-thawed microsomes measured without exogenous substrate was maximal at neutral pH (6.5 to 7.5). When exogenous pectic substrates of various DE had been added, similar optimal neutral pH was observed, and the activity was slightly stimulated (1.2 to 1.8 times). A second optimal pH occured at pH 5.5, but in the presence of low methylated pectin (DE 0.1). As suggested by Lineweaver and Ballou [8] to explain the behaviour of another pectic enzyme -i.e. pectin methylesterase (PME), the mobility and the activity of PMT might be influenced by the presence of polyanionic substrates. On the other hand, the existence of several forms of pectin methyltransferase in flax microsomes might be responsible for such variations of the activity. 

Versieck J, Vanballenberghe L, de Kesel A, Baeck N, Steyart H, Byrne AR and Sunderman FW Jr. (1988) Certification of a second-generation biological reference material (freeze dried human serum) for trace element determinations. Anal Chim Acta 204 63-75. 

Frozen reference materials have been produced by NIST (Wise et al. 1993). These materials do not have the disadvantages of the oils or freeze-dried materials, but are more difficult to transport. Obviously they have to be kept deep-frozen during transport, which makes their use rather expensive. Since the early 1990 s a new approach in this field has been introduced. This concerned the use of wet, sterilized fish and shellfish samples. These samples, packed in glass jars or in tins, were firstly used in the QUASIMEME program as reference materials for inter-laboratory studies (de Boer 1997). Later, when it appeared that the stability was maintained for longer periods, tests for organic contaminants based on this principle were also prepared. 

De Antoni et al. [1.23] demonstrated, that the addition of trehalose during freezing and thawing of two strains of Lactobacillus bulgaricus improved the survival rate differentially, but in both cases considerably. The samples (1 mL) were frozen at 18 °C/min to -60 °C and thawed to 37 °C at 15 °C/min. The solution consisted of distilled water, culture medium and 10 % milk with or without trehalose. It was shown, that after three freezingthawing cycles, milk alone resulted in a survival rate of 24 % or 65 %, while with trehalose this was can be improved to 32 % and 100 % respectively. The efficacy in the case of both strains was clearly different. De Antoni et al. suggested, that the efficiency of milk was related to its Ca2+ content, while the trehalose could replace water molecules in the phospholipids of the membranes. However no mention was made wether other sugar molecules in milk showed any effect. 

De Luca et al. [1.48] showed, that the addition of 5 % tertiary butyl alcohol (tBA) to aqueous sucrose and lactose solutions (up to 40 %) resulted in a frozen matrix, which could be easily freeze dried. De Luca demonstrated by DSC that the melting point rose distinctly (with 60 % solution to -10 °C), but the endothermic of melting returned to 25 %, indicating that not much water had frozen. In solutions with 5 % tBA the exothermic of crystallization became more visible and the melting of tBA could be recognized. 

De Luca, P. P., Klamat, M. S., Koida, C. Acceleration of freeze-drying Cycles of aqueous Solutions of Lactose and Sucrose with tertiary Buthylalcohol (tBA). Congr. Intern. Technol. Pharm. 5th Vol. 1, p. 439-447, 1989... 

Wekx, J. P. H., De Kleijn, J. P. The determination of water in freeze-dried pharmaceutical products by performing the Karl-Fischer-titration in the glass container itself. Drug Dev. Ind. Pharm. 16,(9) p. 1465-1472, 1990... 

Kasrajan, K., De Lucca, P. O. Thermal analysis of tertiary butyl alcohol-water system and its implication on freeze-drying. Pharm. Res. 12 (4), p. 484—90, 1995... 

De Luca et al. [3.1] nominate, under the heading of sensitive biologicals , three product groups for therapy and diagnostics, which are mostly or at least partially freeze-dried ... 

Townsend and De Luca have studied the influence of lyoprotectans (LP) on ribonu-clease (Ri) [3.14-3.17] as a protein model. Lyoprotection is defined as stabilization and prevention of degeneration of macromolecules during freeze drying as well as during storage. With phosphate buffer at pH 3 to pH 10, Ri in the dry stage loses its activity at 45 °C... 

De Luca, P. P. and Trappier, Ed. Design and operational requirements of freeze-drying facilities for pharmaceuticals. The American type culture election and the Merieux Foundation. A compact freeze-drying course on the fundamental aspects on the preservation of sensitive biologicals. Washington DC. April 2-4, 1990... 

Above the freezing point of silver, Tgq is defined in terms of a defining fixed point and the Planck radiation law, and optical pyrometers are frequently used as temperature probes. The Comite Consultatif de Thermometrie gives a thorough discussion of the different techniques for approximation of the international temperature scale of 1990 [2, 4],... 

Czymmek KJ, Bourett TM, Howard RJ. Immunolocalisation of tubulin and actin in thick-sectioned fungal hyphae after freeze-substitution fixation and methacrylate de-embedment. JMicrosc 1996 181 153-161. 

The minus sign of A /m reflects the way water expands on freezing. This expansion explains why a car radiator cracks in cold weather (if it contains no de-icer ) the water freezes and, in expanding, exerts a huge a pressure on the metal. 

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