From: Mike Darwin <75120.575@compuserve.com>
Subject: Mirrors and cracks
Date: 12 Apr 1995

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Date: 11 Apr 95 17:03:19 EDT
From: Mike Darwin <75120.575@compuserve.com>
Subject: SCI.CRYONICS Mirrors and cracks

Yvan Bozonetti's post on preparation of telescope mirrors was of great
interest.

The problem of cooling large masses of glass is of more relevance than
Yvan thinks since cryopreservation patients do contain large amounts of
glass.  In fact, a patient treated with 50% glycerol (7+ M) will be
nearly half glass.  And it will be a weak glass because of its
interleaving with ice and the fundamental nature of glycerol-water
glasses.

Is the Angel that Yvan talks about the same as the C.A. Angell who is an
expert on glasses and was (at least recently) at Purdue University in
Indiana?

I think the fact that extending annealing time works for large, unstable
glass masses is of extreme interest and potential utility to cryonics.  I
think it is also important to note that while CI, Alcor , and CryoSpan
have been cooling patients slowly (1 week or more) and in CI's case they
see no cracking in sheep brains, it is important to realize that cracking
may occur during movement, handling, etc.  Being able to prevent this by
extending the annealing time to many weeks is of great interest.  (For
instance, to my knowledge CI did not jostle, move or otherwise inject
mechanical energy into the sheeps heads after the cooled them).

Finally, can Yvan provide me with references on Angel's rule for cooling
telescope mirrors?


Mike Darwin