X-Message-Number: 3845 Date: Mon, 13 Feb 1995 22:18:40 MST From: "Richard Schroeppel" <> Subject: Cracking experiments Bob Ettinger reports that Dr. Pichugin has verified that a particular slow freezing schedule avoids the cracking problem. I'd like to know some more about cracking: Could Dr. Pichugin follow the Alcor protocols that resulted in cracks, and verify that his experimental setup does get cracks? (I.e., that the sheep-head method does show up a cracking problem where one is known to exist.) Secondly, could someone develop a heat-transfer model that predicts (non)cracking based on cooling rates & whatever other factors are relevant? I'm envisioning something that uses anatomical information to model thermal stress in a cooling head. If slow cooling is the only important factor, this would suggest that either rapid cooling causes cracks at the time of cooling (which went unnoticed), or r.c. freezes in a stress pattern that eventually cracks - and that slow cooling of a solid nevertheless allows stress release. I find both alternatives somewhat implausible. A third disquieting possibility is that cooling at any speed freezes in a stress pattern, and even the slow-cooled sheep-heads would crack if left in the LN2 dewar for a couple of years. What is known about patient fragility? Has Alcor examined their patients after the move to Phoenix? Rich Schroeppel Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3845