X-Message-Number: 20965
From: 
Date: Sat, 25 Jan 2003 17:23:56 EST
Subject: Re: CryoNet #20950 nano

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From: Henri Kluytmans <>:


> 
> It does not use a "centrifugal pump" but a "Molecular Sorting Rotor". 
> It does not seperate molecules by using centripal acceleration, but 
> it rotates relatively slowly and it uses binding site "pockets" 
> (along the rim) to seperate molecules (by Van der Waals force).

and it releases them how?...
> 
> >First, why diamond? graphite sheet are nearly as strong and there is a 
> well 
> >established technology to make them in the bulk.
> 
> Nope, a graphite sheet is only one layer of atoms thick, a diamond 
> wall can be made as thick as you want, and can thus be made much 
> stronger. (In this case about 10nm thick.).

Nanotubes can be produced with multiple sheets, same for buckyballs.



> "Each storage tank is constructed of diamondoid honeycomb or a geodesic
> grid skeletal framework for maximum strength. Thick diamond bulkheads
> separate internal tankage volumes. Available structural mass is equivalent
> to a 10-nm thick (~60 carbon atoms) 2.2 micron x 2.2 micron diamond sheet,
> enough material for 1000 compartments ~(40 nm)3 in size for all tanks.
> Compartment walls are perforated with sufficient holes of varying sizes to
> allow gas to flow easily between them, with larger compartments nearest the
> rotors graduating to smaller compartments more distant from the rotors to
> encourage isobaric entrainment."


Do you think one second to the complexity of that 3D structure? To think a 
(perfect) gas can flow freely in it is beyond my understanding, at best 
you'll have a kind of very non linear liquid with strong surface effects.

> >It seems that has been done for hydrogen, why to build atom by a atom a 
> >diamond structure? Diamond or not, carbon and high pressure oxygen are a 
> >noxious mix. 
> 
> Didn't you read : O2 and CO2 are stored in seperate tanks.

The problem is that diamond (carbon) + O2 = CO2 + energy + destruction. One 
bad molecule in the rotating part and the system grind to halt or the motor 
is sufficient to overcome that and you have the activation energy to start 
the combustion process. It may be worst: This system has nearly no thermal 
sink so any concentrated energy input, for example a cosmic ray particle, 
could start the fire. Even thermal energy is a bad concept at that scale, you 
may have to speak about discrete mechanical vibrations or phonons. Resonance 
effects may concentrate energy in a particular zone and set a fire. 

To make such a structure would be very costly, to make it safe would be quite 
another challenge.

> 
> >Do you really would try to make such a complex, unstable, costly 
> >thing 
> 
> Yes, because they will not be costly to fabricate using real MNT !
> ( Using reproducing systems, exponentional production and 
> convergent assembly systems.)
> 
> And it will not be unstable : in the design an extremely 
> conservative 100-fold structural safety margin is used.


The problem here is that you think on a classical physics basis, not a 
semi-quantum one as you should. A simple radiography would set fire in all 
your respirocites for example, simply because you assume there is a bulk, 
macroscopic thermal sink where there is not. I don't say that problem is 
without solution, you could shift from diamond to alumino-silicate for 
example. You have to think a lot on processes going on at these scales before 
throwing billions on billions in that industry.

> 
> Maybe I should add : All conservative approaches do not assume that 
> self-reproducing nano-systems will be used inside de body, they 
> assume that fabrication of biological repair or enhancement systems 
> will take place outside the body.


... One good idea at least :-)

> I guess you didn't read the complete article (or you didnt 
> understand it?).
> 
> Next time do not read the abstract only. And if you want to 
> criticize the fundamental basics of MNT, read "Nanosystems" 
> first and then focus your critic on assumptions and 
> derivations in this book.
> 
I have read far more than the abstract, but I am not sure it was a good time 
investment.
My position is simple, I restate it here: Micrometer classical technology 
using lithography is clearly a possibility with some potential applications. 
Most "nanotech" progress are in fact in that domain. In cryonics, this may be 
useful for microsurgery for example.

True nanotech is at the scale of atoms or a small group of them, most 
progress seen here are simply biochemistry or plain chemistry in disguise to 
attract more money. Theoretical large schemes lack the quantum thinking they 
desserve. Assemblers for billion parts systems are no more than dream pipe. 
Self assembly is not best at that scale. You can probably have a self 
assembly system working on at most ten parts, no more. Ribosomes may do more 
but they are limited to 20 different building block assembled into a string. 
Nano systems seem to have far more than 20 different parts and need 3 
dimensional work, not one.

To make that (or a small part of that) a reality, you'll need tens of 
billions dollards/year for one century or so. Where did you find that money? 
I have never seen a strategy to go from zero to that astounding level of 
activity. Is it possible, if the market is so great than nobody find in each 
case a simpler, cheaper solution?

To a cold eye, nano capacities seem largely overstated. The reality one 
generation from now may be somewhat biter.

Yvan Bozzonetti.

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