X-Message-Number: 4748
Date: Wed, 9 Aug 1995 15:28:24 +0200 (MET DST)
From: Eugen Leitl <>
Subject: multiple comments on last cryonet digest

 
emulating T.D., I have a bunch of remarks on the last
cryonet digest's posts:

[ David S. Stodolsky forward on new information recording tech ]

> equivalent of 12,000 diskettes (or 180 CD-ROMs) onto a 1-inch long
> pin of stainless steel. (Information Week 7/24/95 p.12)

I wonder how one keeps stainless steel from corrosion for 5 kyrs...
Gold would have been better, or any inert solid. Even so, there is
no better replica than the original itself: the brain. One will need
a lot of surface to record that level of detail unless a essential 
feature  extractor is used. (...and one just better'd stick a memo onto 
cartridge on the format used and the kind of information contained in 
all those tiny pits.. they have lost a lot of data this way even
now: forgetting the data format. Some companies make their living
by providing data conversion services.). 

But you are right: AFM-typed 2d structure defects are the thing to
watch for.  I recall reading a WS2 or MoS2 reversible atomic-sized
defect writer with STM in Nature. Definitely an interesting 
technology, though very sequential, unless one uses VLSI STM arrays,
which they had succeeded in building just recently (small arrays,
relax).

Another thing:

I just hate to do any more nanotech bashing in here, but this 
"defrost your brain by hydrogen+fluorine pellets" thread has 
finally gotten at me.

The problem is not merely safe containment, transport, initiating
and dissipating of a highly reactive species. The brain is not a 
vacuum: it contains finely structured matter. Though I would like 
to see masses of nanites burrowing through cells sans damage (they 
really ain't that small, these critters) what is the amount of 
species you need to have to trigger to release the necessary chemical 
energy to elevate the temperature sufficiently? Now add to that 
volume the amount of transport/control/containment circuitry 
(which is vastly larger). This is the biggest contra argument.

to 1): Not only is HF reactive, fluorine itself is a very, very 
reactive species. Ralph, please do not mix the macro and nano
scales to something convenient albeit far from reality. Even 
if you have some fluorine contained in a perfluorinated surface 
(which can't be all 111 btw, since it has to be hollow/cyclic): in 
some cases random noise will accumulate enough energy to 
breach it, being only a surface layer and not a macroscopic
iron fluoride layer in the macroscopic containment, the rest of 
fluorine rapidly escaping into freedom & wrecking havoc there. 
Keeping things cool slows things a bit, but one has to do an 
actual calculation to check the viability. Fluorine is Evil, imho.

Yes, hydrogen/oxygene is better, since hot nasty product needs
not be gotten rid of and oxygene is quite tame as compared
to fluorine. The problem is the form of energy: excited species have a 
lot of energy in a small volume. They can either radiate it as (short) 
EM, to be reradiated by increasingly longer lambda or dissipate it 
directly to kinetic energy by banging into their neighbours.
 
In any case will bonds in immediate vicinity be broken which needs
a thick container wall. One can probably limit the damage to the inert 
shell (which will go bang blowey anyway), but this introduces a 
volume/shell bulk constraint, even more water onto the mill of the first 
contra argument.

The problem of ignition: easy. One has merely to create a tiny hot
spot or produce a tiny amount of free radicals to start the chain 
reaction. The fuse can be triggered by convenient energy levels nanites 
operate at. No problem, here.

to 2) Tissue cooking? Unlikely, provided your pellets are that small as
   you propose. Why complicating things by trying to control what
   is essentially uncontrollable? This diamondoids are getting to break
   real fast, unless you propose using a great many of layers, which
   makes the cargo ratio abysmal. Using small nanogrenades, releasing
   adequately muffled energy portions is simpler. Don't start modifying
   tissue in the immediate vicinity, you'd be making more damage that
   you set out to combat.

to 3) if you have such degrees of control, heating tissue with 
  nanogrenades is an unbearable crude in compare to it. You'd could
  merely twiddle your atomic thumbs back and forth at a sufficient 
  rate to dissipate sufficient energy.

to 4) there won't be too much of the pellets left over, fragments 
  at most. And, if you know how to make lymph-soluble perflorinated
  diamondoid pellets, please tell me, since I don't.

On the whole: a nice exercise of spirit, but wholly impracticable.
Masses of nanites operating in confined enviroment at proposed speeds
will produce enough heat (and burn enough chemical fuel) to pose
multiple _severe_ problems already. Please Ralph, don't get mad 
but exactly ideas like these make nanotech (and partly cryonics, 
being based on nanotech) very hard to swallow for the average 
scientist. And it is not always mere stupidity which prevents
them from accepting nanotech, either.

> Subject: fixation + freezing?

Joe: you are taking words of my mouth. I planned to do a 
pro mild fixation + cryopreservation post even this week.
I wanted to cite some immunochem fixation guidelines to back 
up the thing. Too late.. ;P

I wouldn't rely on fixation as the alone technique as the
amount of fixative necessary for full conservation will
introduce more artefacts than vitrification alone would
ever had. However, using mild fixative as part of the 
cryoperfusion procedure might increase the level of structural
detail both at the cell morphologic and possibly even molecular
scale (since antigen density is influenced only slightly
according to the immonochem text, part of the damage being
reversible e.g. for mild concentrations of methanal).

I would already start proposing using low level of e.g. 
methanal as auxiliary cryoperfusion agent after some screening 
study on its effects, were there not one powerful contra:

Mike already told us some of his reasons for using off-shelf 
sterile methods. For the same reasons medics and relatives 
won't accept fresh patients as patients ("What!? You are using 
some embalmment fluid on him?!? I thought you are supposed to be
saving, not killing him!") if fixatives are used routinely.

I think there are technical reasons why we should consider
evaluating mild fixatives as co-agents in cryoperfusion. But
how can one sell that to the customer, I wonder?

> And even if THAT's not a problem, we are certainly adding insult to 
> injury by heaping poisonous fixatives on top of freezing/thawing damage.  
> Such treatment might delay the patient's recovery, even if the LN keeps 
> flowing steadily.

I think that current "minimum artefact policy" cryoperfusion methods have
a very sound basis. However, if the amount of vitrification artefacts
can be noticeably reduced at the cost of slight denaturation (which
is not all that heavy (and partly reversible) if one considers repairing 
the additional death cause and rejuvenation, which is practically 
equivalent to rebuilding upon blue pause) we should at least have a 
look at fixation as auxiliary method.

Concerning deuterium oxide (D_2O) for perfusion:

m.p. 3.813 deg C
b.p. 101.431 deg C
dens. 1.104

Otherwise chemically (almost) indistiguishable from normal
water (is in fact containt in normal water in minute amounts).
I think it still has the water anomaly, albeit with an offset
(does anybody have data?).

However: you can easily kill any organism by substituting its
body water by heavy water (great for Agatha Christie whodunit
but worthless today as MS isotopic fingerprint at high res 
will look _very_ unusual, provided pathologist grows suspicious 
enough to do an MS which he probably will).

The reason is denaturation: since in biology form follows
function, even a slight deviation from a structure has
large impacts, breaking brittle bioequilibrium machinery
depending on homeostasis.

(One can warp simple organisms into heavy-water based
ones if one increases D_2O concentration _very_ slowly.
Normal water will be toxic for them, then. This is not
acclimation, but evolution in the small, hence it
does not work for complex organisms.)

Additionally, I'd say it won't have any noticeable impacts
on vitrification as its structure isn't that different from
water ice. However, provided proton/deuteron mobility has a
major impact on ice growth kinetics an effect might be visible,
if barely.

> 	As to Hans Moravec, well... let me paraphrase from a 
> 1989 (+- 1 year) interview in Omni magazine.
> 
> Omni:	What do you think of cryonics?
> 
> Moravec: Cryonics is very crude.  I'm actually much more interested
> 	 in the prospect of using hyper-advanced technology
> 	 to resurrect deceased persons using clues left behind
> 	 in their surroundings.

Brian: are you sure that Omni got it right or that Hans did really
meant what he said? Though he _has_ some funny notions, I just can't
believe him discarding the only solid body of evidence one has. I'd
be very surprised indeed, if he'd really meant that exactly how
it stands there.


-- Eugene


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