Stored cryogens

Samples of Concentrates. Concentrates or dried organic residues from extraction or lyophilization processes should be stored at —70 °C or lower. Little information is available regarding the stability of samples stored cryogenically. Thus, research should be conducted in this area to determine the best method for the storage of such samples to prevent the degradation and development of artifacts. 

Harvest the remaining cells by centrifugation, resuspend in freezing medium (2 mL/spleen) and dispense into cryotubes in 0.5-mL aliquots. Freeze the cells and store cryogenically. 

NS-0 myeloma cells are normally kept stored cryogenically and so should be resuscitated 3 d before conducting the fusion. 

Reproduced by permission p. 283 Multi-celled human embryo 2.5 days after it was removed from the womb and stored cryogenically at the Bourn Hall Fertility Clinic, Cambridgeshire, England, photograph. AP/Wide World Photos. Reproduced by permission p. 285 CAT scan, photograph. 

Stored cryogen - Superfluid helium - Solid nitrogen - stable and passive - low temperature (1.3K using sup He) - limited lifetime (1-2 yrs) - massive and bulky - complex interfacing (storage)... 

A. A. Fowle, Estimation of Weight Penalties Associated with Alternate Methods for Storing Cryogenic Propellants in Space,/ Contract No. NAS5-664, Report No. 63270-11-01 (May 1962). 

BACK-DIFFUSION INTO STORED CRYOGENIC LIQUIDS VENTING TO THE ATMOSPHERE ... 

Special equipment must be used to contain, transfer, and store cryogenic liquids. This equipment is specially designed to withstand the extreme differences in temperature and rapid temperature changes experienced when working with these liquids. 

In addition to blood, animal semen is also stored cryogenically. For example, over 5 million dairy cattle per year are bred with cryogenic frozen semen in the U.S. alone. One prize bull, Achilles, has sired more than 300,000 calves. In perhaps an odd use of cryogenics, the branding of cattle using a cryogenic iron has been used for many years. 

The energy transferred per unit area of surface by free molecular conduction between two surfaces such as those maintaining a vacuum around a stored cryogenic liquid is the product of the mass flow rate of molecules to the surface and the total change in kinetic energy per unit mass Ae, or... 

The shape of a cryogenic storage vessel is selected to minimize the surface area to volume ratio of the container and thereby reduce the heat inleak to the stored cryogen. A spherical vessel has the smallest surface-area-to-volume ratio and, thus, is frequently used in a fixed storage system as well as in mobile tanker ships. Cylindrical vessels, which are easier to fabricate and transport, are probably more widely used, however, because their surface-area-to-volume ratio is only slightly larger than that of a sphere. 

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