X-Message-Number: 2137
Date: 21 Apr 93 08:39:00 EDT
From: "Steven B. Harris" <>
Subject: CRYONICS More Cold-Room Design
Perry Metzger writes: >>Here is a wacky idea -- possibly a bad
one, but who knows. Presumably, a mixture of water and cryopro-
tectants such as the ones we use on patients would have a "knee"
EXACTLY where we want it -- at the glass transition point for the
patients!<<
Answer: I hope not, for that would mean we'd failed in our
goal of vitrification!
Alas, Perry, remember that the magic "glass transition temp"
is not a very objective thing, and is not well defined. It's
only a descriptive term for the _qualitative_ effect produced
when the liquid gets so viscous as to resemble the behavior of a
solid. Where you decide this is true is to some extent arbi-
trary, although over the widest temp range you can always find
two temps for which everyone will agree the substance is "liquid"
and "solid" (this is another "sorites" paradox problem).
In any case, no objective phenomenon like heat release is
involved, as in freezing of liquid into crystals, so no tempera-
ture "knee" as we see in phase transitions is produced. In
short, if our patients are really vitrified, they'll warm
uniformly from vitrified to nonvitrified with no big changes in
heat capacity. If not, we'll know that (again) they weren't
really totally vitrified in the first place. In fact, the most
sensitive test I know of for successful 100% vitrification is to
warm the "vitrified" tissue with constant heat input and SEE if
temperature "knees" are produced. The amount of "knee" seen is
an indicator of the amount of residual ice in a vitrified sample,
and therefore an index of the amount of failure in technique (one
can see both anomalous heat production near Tg as any residual
ice crystals grow in the newly produced liquid, and later an
anomalous heat sinking effect near the ice point, as any water
ice melts; obviously total ice formation is sensitive to warming
rates, and so is the knee effect). We'll be doing this kind of
measurement with experimentally vitrified dog heads in the not
too distant future. Another necessary control is that when we
get to trying vitrification on humans, we'll want to perfuse the
left-over body of one of our neuro patients, then allow the body
to warm through both the glass transition and water-ice freezing
points with thermocouple monitoring, to look for exactly this
sort of thing. Similarly, although I hope it never happens, if
we ever have to remove a vitrified neuro patient from suspension
for some reason, we'll also want to do a controlled warmup there
to collect this vital information.
To Brian Wowk:
Okay, I believe you about the floor loading and accept your
point that we don't need direct circulation through ballast
containers. It occurs to me then that in the matter of ballast
we don't want to spend time re-inventing the wheel. There are a
number of kinds of rigid plastic containers of fluid on the
market sold commercially as cold-packs for picnic coolers, and as
cold-packs for commercial shipment of thermally perishable
medical supplies. I get such things all the time in the mail
packed in with biologicals and chemicals. All these containers
are sealed, and none appear to have much problem with expansion
bursting, even though I suspect that all are filled with some-
thing which is mostly water. We need to contact some of the
biggest companies that make these things (like Gott), and ask
what they'll charge to custom manufacture a few thousand 2-liter
ones with our own custom water/ethanol mix inside (mix to be
determined previously by experiment, as described in my recent
messages).
If we fail in this, another possibility is the stackable
cubical 5 gallon plastic jugs sold as emergency water supply
containers in survival stores. These might have to be pre-
frozen before capping to prevent rupture, but after that should
work okay (say-- does anyone make a simple valve which passes air
but excludes liquid?). At 40 lbs, such containers might be a bit
unwieldy, but remember that we don't have to use just a rope tied
to a handle to move them-- we can also cradle containers very
stably in fine nylon netting. Clearly the design of a future
cryonics facility will center about a basement cold room, above
which is a work area with high ceilings and a LOT of overhead
cranes, tracks, and electric winches. We'll call it the "over-
room."
Steve
P.S. By the way, as I expect that our cold room will be the
central feature of a facility built in Scottsdale, Az, I am
struck that there is one more advantage to a lot of ballast and
200% over-capacity dual refrigerators: they will allow us in
normal operation to shut down our refrigeration system entirely
during the hot part of the day, and do all of our heat pumping
sinked only by the cool of the desert night, when the gradient is
20 C less than in the day. If this is not quite enough time
there is the solar house principle: if we use a fair-sized
reservoir tank for our cooling water, we can stretch our refri-
gerator on-time by employing dual external air heatsinks to cool
both hot reservoir water and refrigerator sink during the first
cool of the night, and using the cooling water itself as a closed
sink without external air sink during the first part of the hot
day. With a big enough reservoir, of course, we can refrigerate
24 hours a day and dump heat only at night. In any case, if we
can choose to dump heat (whether directly from the -135 C
refrigerators or indirectly from the reservoir) only at those
times when we have a good natural outdoor heatsink, this will
take a big strain off our facility office air conditioning
system, since it then (ordinarily) won't have to handle ANY of
the cold-room heat.
Of course, the above can change if necessary. Here is another
idea: we should also be able to arrange things so that in
emergencies the facility office air-conditioning system CAN be
diverted to do NOTHING BUT sink the output of the cold-room
refrigeration system AND ambiently cool just the "over-room"
(we'll have to duct and vent the "over-room" specially). Thus,
if one -135 C super-refrigerator fails we can employ the indoor
air conditioning system round the clock for exclusive use as a
booster for the remaining refrigeration system (superchilling the
input water), until repairs are made. Better to have Alcor
personnel in most parts of the facility swelter for awhile than
patients warm up! Anyway, in such an event I expect that admin-
istrative functions and caretaker living could always be tem-
porarily moved to the "over-room" until the emergency is re-
solved.
Steve
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