Shell-freezing

Cooling by Liquids Shell-Freezing and Spin-Freezing... 

In the cooled bath the container can be rotated slowly (shell-freezing) or quickly (spinfreezing), as shown in Fig. 2.1. The aim of both methods is to reduce the thickness of the liquid product before freezing to e. g. 15 or 20 mm. For production purposes, this method can not be used, since the liquid must be removed from the surfaces before loading the vacuum plant. This can be done by hand for a limited number of containers, but not in a production scale. 

Shell-freezing a flask is placed in cold bath in such a way, that the neck of the flask is covered by the liquid. A motor turns the flask and the product freezes on the wall. 2. Spin-freezing one or more bottles are fixed to a jig and immersed in the bath. The jig turns the bottle(s) so fast around its (their) axle(s), that the liquid is distributed evenly on the wall(s). 3. Shell-freezing the bottles are placed on cylinders in the bath, the cylinders turn in the bath. The bottles are turned by the cylinders around their axes (Fig. 3 from [2.20]). 

Cooling by Liquids Shell-freezing and Spin-freezing... 

Table 1. Response of Garter Snakes to Earthworm Wash Subjected Repeated Shell Freezing and Repeated Lyophilization. to... 

Oxygen is the first member of Group IV with six eleetrons in the outer shell. It is a eolourless, tasteless and odourless gas whieh eondenses to a blue liquid and freezes to a blue solid under... 

Examples freezing N2(g) + 3 H2(g) - 2 NH,(g). expanded valence shell A valence shell containing more than eight electrons. Also called an expanded octet. Examples the valence shells of P and S in PC1S and SFh. expansion work See work. experiment A test carried out under carefully controlled conditions. 

Lewisite (C04-A002) has been mixed with sulfur mustard (C03-A001) to prevent the sulfur mustard from freezing in the shell as well as to enhance its toxicity. 

Hanafusa [1.36] showed with this method, how the amount of unfrozen water in a 0.57 % solution of ovalbumin reaches practically zero at -20 °C, if 0.01 M sucrose is added (Fig. 1.51). For globular proteins Hanafusa described the freezing process as follows between 0 °C and -20 °C, water molecules from the multilayer hydrate shell are decomposed. Be-... 

The DNA solvation shell consists of about 20-22 water molecules per nucleotide of these, — 15-17 waters associate with the nucleoside and —5 waters associate with the phosphate group [13,14]. Water outside the solvation layer is termed bulk water. Upon freezing, the DNA solvation water forms two primary phases the ice phase, consisting of one or more of the crystalline forms of ice, and a DNA-associated phase, consisting of ordered water which comes in direct contact with the DNA (primary layer) and disordered water in the secondary layer. DNA hydration is expressed in terms of F, the number of water molecules per nucleotide. 

In an aqueous solution of DNA, the water outside of the solvation shell is referred to as bulk water. When DNA solutions are frozen, the bulk water crystallizes as a separate phase—ice. Ice does not form if the concentration of DNA is brought to a level where only the solvation shell remains, about 20-22 waters/nucleotide. If brought to this concentration slowly, a film is formed. Freezing a film does not create ice. Another type of sample is prepared by first lyophilizing DNA and then letting it sit at a preselected humidity that determines the level of hydration, typically 2.5 < F < 22. Subsequent freezing of these cotton-like samples does not yield ice. 

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