X-Message-Number: 5704 Date: Sun, 4 Feb 1996 16:29:50 MST From: "Richard Schroeppel" <> Subject: tv coverage; fast freeze Did anyone see the cryonics segment on NBC TV a few hours after the Superbowl? I happened to catch the tail end. They showed a big dewar being lowered into place, and the winch setting stuck. The tone of the narrator was positive, friendly, serious, etc. ----- Has anyone asked the South African doctor to post his paper about quick- freezing and reviving a rat heart? ----- Let's suppose for the sake of discussion that ultra quick freezing is a good thing to do. I suggest we brainstorm a bit, looking for ways to achieve it. Some random thoughts in that direction: a) Microwave freezers seem to violate the 2nd law, I'm told. :-( Therefore, the heat has to be removed by conventional means: Convection, conduction, radiation. b) The total amount of heat removal required is a little bit more than 540 cal/gram. We can assume ftsoa that the patient is precooled to a little above freezing, and must be frozen to a few degrees below. (Cooling ice from 273K to 77K adds another ~200 cal/gram, and this might have to be "instant". But it doesn't change the rough magnitude of the heat to be removed.) The implied volume of LN2 (as the cooling agent) is tolerable, but having it all vaporize at once could be a nuisance. c) We might be satisfied to insta-cool the body in sections: Brain first, lungs next, etc. Could be a niusance to rejoin sections. d) Heat transfer scheme: We invent "cold dust". Little 2-micron dewars, with 1.5-micron centers of LN2 or LHe or very cold ice. The exteriors are at 5C. We perfuse the patient with the cold- dust mixed in the blood. A radio signal is sent to the dust, and they all let loose at once, freezing the patient. Problem: Total volume of the blood is < 10% of the patient, and the amount of cooling you can get isn't enough to freeze even an equal volume of water, much less 10X. Problem: If cooling involves the LN2 or LHe vaporizing, the volume change is a problem. Problem: Is it possible to make a micro-dewar? Even in theory? There are a few chemical reactions which lower the temperature of the reactants -- would they work better? e) Next try: We run thin metal tubing through the patient's major veins, say .1 mm and larger. Pervasive enough so that all tissue is within 2mm of a tube. (How big is a rat heart?). A big pump forces coolant through the tubing. Real fast. (e) at least doesn't appear to violate physical law, but the engineering challenges are daunting. f) Superconductors and LHe have interesting heat-conduction properties. Can we use make use of them? Doug? Edgar? Rich Schroeppel Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=5704