X-Message-Number: 3567
Date: Sun, 1 Jan 1995 18:11:14 -0500
From: 
Subject: SCI. CRYONICS damage & temp

Ben Best (#3557) has some comments on types of freezing damage and on storage
below the temperature of liquid nitrogen.

Thomas Donaldson (along with many others) seems to think that cracking is a
serious problem--perhaps the most serious problem in cryonics. Ben thinks
other problems may be more serious, and I tend to think Ben may be right
here. Cracking--at least if it is clean enough--may present a relatively
simple jig-saw type puzzle for nanotech repair, as Ralph Merkle points out,
whereas irregular damage of other types may be more formidable. (But if we
depend on spontaneous repair, or repair without nanotech, the story could be
different.)

Incidentally, Ben says Cryonics Institute has contracted with Ukrainian
scientists to verify our observation of lack of cracking in sheep brains with
our methods, including much slower cooling and rewarming than others have
usually used. Actually, Drs. Pichugin and Zhegunov have already confirmed
this--on all levels--with the first sheep head; the second one to reconfirm
is in progress.

On the advisability of storage below liquid nitrogen temperature, I think Ben
is wrong. Storage stability is not the only question; there is also the
question of damage en route. My impression is that different kinds of damage
may occur in different temperature ranges, and a longer trip is more
dangerous. It seems pretty clear that liquid nitrogen storage is stable
enough, and we want to avoid unnecessary changes.

Robert Ettinger
Cryonics Institute

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