As a result, I will continue the discussion at crnano.typepad.com, CRN’s blog. I probably won’t be checking back here unless someone emails me: cphoenix at CRNano.org.

Anonimouse, we can’t do a mind-meld, so I can’t download to you every detail of my information. If you want more detail on a topic, ask, but don’t accuse me by implication of not knowing before you even ask.

There are not a lot of molecules smaller than acetylene. Acetylene has only four atoms, two of them hydrogen, and they’re colinear. Methane is fatter, and acetylene is the smallest two-carbon hydrocarbon. A large fraction of other molecules will be polar, which provides a basis for sorting in addition to steric matching.

Check out the neon pump at Nanorex.com (the PDB file is here at imm.org).

This is very different from your sodium pump, but it is a detailed design that ought to work.

“Attract” was, as you note, an imprecise description. I didn’t mean to imply a long-distance force. The binding site will have affinity for the molecule, which will encounter the binding site many times per second even at fairly low concentration. For more details, read the appropriate sections of Nanosystems and Nanomedicine.

I don’t know what sensory modalities are available in water that are not available to a proximal probe in vacuum. I don’t think you know either.

Chris

I think it was Heinlein who said “I could be wrong, but I’m positive.”

All the best.

What atmospheric pressure will be there? What environment will all those nanomechanical details work in?

I’ve started to reply, but found that I can’t find anymore the composition of, say this bearing. As far as I remember, this model contains numerous Si-S and S-H bonds. Am I right?

ESB is an absence rather than a presence, and so it takes a while to realize its existence. Like the dog that didn’t bark in a Sherlock Holmes mystery, ESB is the clue that explains why eutactic molecular nanotechnology hasn’t happened since Richard Feynman’s 1959 speech “There’s pleny of room at the bottom.”

The sensory blight of the eutactic environment, as compared to the sensory richness of the aqueous environment, makes each and every one of the MNT stuctures and systems proposed to date impossible to build. I use the term “impossible” advisedly and throw the burden of proof on the proposers of those MNT designs to prove otherwise.

Christine, it may take you another twenty years to appreciate eutactic sensory blight, and to understand its ramifications. But you will come to do so.

For example, you say “The binding pockets are shaped to preferentially attract specific molecules.” This is an interesting statement. What do you mean by “attract”? Are you envisioning forces which reach beyond the range of Van der Waals forces? Or is this statement more of a wish than an engineering specification?

It seems to me there are lots of atoms and molecules smaller than an acetylene molecule which would be swept up by the supposed rotary mills, in the same way that the spaces in the chain on my bicycle sweep up grit smaller than the gear teeth on the sprockets.

Do you really have some detailed design that can remove water molecules, for example, once they have passed into the space beyond the rotor? If not, it seems to me you’re just blowing smoke, attempting to confuse the issue rather than clarify it, with the aim of creating confidence in the MNT vision. But this is, or should be, more than a confidence game, and you must not create the perception that you are a confidence artist.

By way of comparison, take a look at the sodium pump anaimation at http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html
for an idea of what a working design looks like. The system is pretty well understood, as is the method by which it is built. Can you specify a rotary mill in similar detail? A method of building it? A power source?

Better yet, take a look at oxidative phosphorylation at the same site at http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/oxidative/oxidativephosphorylation.html.
This is how real molecular machinery works.

Now, it’s been almost thirty years since Drexler came up with his dream of molecular nanotechnology, and I don’t see much progress. Lot’s of CAD designs, yes, but never a way to build them.

Christine, I really don’t think waiting another twenty years will make much of a difference. What do you see changing in the next twenty years to make any of these designs realizable?