X-Message-Number: 3424
Date: 21 Nov 94 14:17:08 EST
From: yvan Bozzonetti <>
Subject: CRYONICS: CO2 drying

Emma Young reports in the November 19 issue of New Scientist about 
supercritical CO2 drying. At 40 degree C and 90 bar, carbon gas becomes 
supercritical, it is at the same time a gas, a liquid and a solid. Its 
ability as solvent is used to extract cafeine from whole coffee grains. 
With 2,2 dimethoxypropane, water is turned into methanol and acetone, both 
are then removed with supercritical CO2 ( water is not directly soluble 
into CO2).

	For objects such wood there is less cell damage than with freeze 
drying. It remain to be seen if the CO2 bath doesn't remove usefull 
molecular compounds. If there is no such problems, CO2 could look as a 
promising way: a full processing takes four days against months for a good 
freeze drying.

	Without liquid water, protein are denatured and there is no proof 
the effect would be reversible. Such conservation must be seen as an 
information preservation for copying on a material or virtual medium. It 
would for example be legal in British Columbia, because there is no 
possibility to live again for the storred corpse.

	On the technical ground, the 90 bar presure is less than what is 
found in air bottles used for diving. The temperature is not very high and 
some antioxydants could limit any chemical destruction.

	Yvan Bozzonetti.

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