X-Message-Number: 9523 Date: Sun, 19 Apr 1998 16:48:44 -0400 From: Paul Wakfer <> Subject: Re: Cryostats Ettinger wrote: > First, the oldest CI fiberglass unit now in active use is, as John Bull says, > about 11 years old; but the oldest one we have (the first one built) is much > older and still available if we need it. (The capacity is only one full-body; > we will probably use it for other purposes.) And so are some dewars that CryoSpan, Alcor and Trans Time have had in use or on standby without need of any maintenance to date. > Second, the maintenance problem with MVE type units, Again, these are *not* "MVE type units", they are the industry standard of cryogenic (LN2) containers which are made by many manufacturers. > as I understand it, even > in the absence of leaks or gross damage, is from the outgassing or even minor > permeability that very slowly degrades the very hard vacuum required. Unless > this has changed, at some point the vacuum must be hardened again, and the > procedure in the past, at any rate, was to bake it and add new getters. I think this view is about 20 years behind the times. The problem was solved with modern getters and more rigorous (and longer time course) evacuating methods. If these dewars are so costly and difficult to maintain why would almost everyone be using them? If your cryostats were superior why would not more industries, universities, etc. be using them instead? > Third, Paul says all existing types will become obsolete with respect to new > vitrification technology--when and if successful--that will use storage at > higher temperatures than that of liquid nitrogen. (I believe something like - > 135 C has been mentioned.) That is not necessarily true. We have preliminary > plans on the drawing board for fiberglass units that will employ liquid > nitrogen, but will nevertheless provide stable temperatures in the desired > range, and that will use less nitrogen than present types. Perhaps, but patients will no longer be *immersed* in LN2 and the thermal engineering will be quite different. I meant obsolete in the sense that, it will no longer be cost effective to house patients in dewars or fiberglass cryostat (of your design type) in comparison to sheet foam enclosed cold rooms. While the difference between -196'C and -135'C (and the final optimal storage temperature may be warmer than that) may not seem that great to most people, I assure you that the thermal engineering, coolant, and materials requirements are *quite* different. > To build and test > models is one of our many research projects awaiting implementation. (Yes, I > have heard that the "cold room" technology of 21CM is intended to apply to > preparation as well as storage, and perhaps they believe both must be > integrated; but that is another long story.) I believe that you have this all wrong. It would not make any sense to integrate perfusion operations and storage. Perhaps it would for *cooldown* and storage, but I doubt that also. Perhaps someone from 21CM can clarify here. > And that reminds me to remind members that research donations (tax deductible > if made to the Immortalist Society) will be used for many worthy purposes, > some of them not contemplated by any other organizations. This last may well be true, but how can you be so sure you know what is *contemplated* by other organizations? -- Paul -- PS. The URL below is now open for the perusal of all interested readers. Voice/Fax: 416-968-6291 Page: 800-805-2870 The Institute for Neural Cryobiology - http://neurocryo.org Perfected cryopreservation of Central Nervous System tissue for neuroscience research and medical repair of brain diseases Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=9523