<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From:</b> extropy-chat <extropy-chat-bounces@lists.extropy.org> <b>On Behalf Of </b>John Clark via extropy-chat<br><b>…</b><o:p></o:p></p></div><div><div><div><div><p class=MsoNormal><o:p> </o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><div><p class=MsoNormal><span class=gmaildefault><span style='font-family:"Arial",sans-serif'>> </span></span><i>Cheap it may be, but I believe storage at higher temps - as high as feasible for cryopreservation - is what I think has better chances of reanimation. No need for refrigeration, an enclosure can be designed with liquid nitrogen that has a natural temperature gradient. The cooling will still be passive, the same amount of LN2 will be required, but the vessel will be much larger.</i><o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-size:13.5pt'>>…It's simple and cheap to store a brain at -196C, you just put it in a big thermos and pore in some liquid nitrogen, but to evenly store it at -135C would be complex and expensive, you'd need all sorts of fans and heat exchangers and sensors and a computer network to manage it all, and that is a lot of places where a catastrophic failure could occur…<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'>On the contrary. Storing at a stable -135C is cheaper and easier than -196C: -135C is below the critical point of argon. Liquid argon gradually boils off at -135C when held around 30atm (as I recall (it was way below the pressure of our lab compressed argon bottles (which were 200 atm.))) <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'>This turned into a big deal right around 1986 when liquid nitrogen temperature superconductivity was discovered. The boss of the lab where we worked heard that this effect might even work as high as 150 to 160 K range, so he let us fool with setting up a liquid-argon pressure vessel (we wanted to see if it would be a pain in the ass to vent the argon (with the notion that if there is too much of it, argon would displace air and you couldn’t tell until you died.)) Turns out it is easy to maintain -135C. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'>There are other things that can be added to the argon to raise the boiling point even higher. I had thought of oxygen, but that didn’t raise the BP much at all. Besides that, venting oxygen into a lab isn’t a good idea either: if there is a lot of it in one place, it makes a fire hazard.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'>I never heard that superconductivity much above liquid nitrogen temperatures ever did happen.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'>If we can find any benefit (or even non-harm) to storing brains or full body at -135C, I know how to do that.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'>spike<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:13.5pt'><o:p> </o:p></span></p></div></div></div></div></div></body></html>