Sudarshan.P

Thank you very much for your elaborate response.

* I guess this gives me the confidence that nanohackers can think about nanostructures using physical analogies to produce physically sound nanostructures if they are careful.

* Sad to hear that fabrication of tori in any substantial quantities is a long way off. I guess I just indulged in some wishful thinking ;-)

* Regarding the Space Elevator, what can I say… These days we all(especially the common public) are standing on “very slippery shoulders” of midgets piled on top of each other. Unless one is deep into a field, it is nearly impossible to figure out even whom to listen to. I was under the impression that if NASA is encouraging the space elevator concept maybe it is quiet close to being sound and feasible at least in theory.

* I was excited to hear that with sufficiently long nanotubes, the strength of the nanotubes scales with length. Wow that is really cool. Bronze Age to Iron Age by just waiting for nanotubes to grow longer!!! Sounds really cool. How long will it take to reach such lengths? Is there something like the Moore’s law for the length of synthesized nanotubes?

* While my fascination for looped structures and knots in making superstrong materials has vanished, I have begun to wonder about the usage of knots in nanotechnology as a “design pattern”. There is something intrinsically beautiful about knots. Even with a single long nanotube you can create wonders. There is something very digital about knots. You cannot have a 2/5th of a knot. You only have a knot or don’t have one. And there are various kinds of knots. At the same time if you have 3 knots on a nanotube, they can have an infinte number relationships with each other. This design space looks really exciting!!!

* The surface of a nanotube is fairly inert. But you can possibly construct really amazing complex structures by using a single tube or a few tubes by tying knots. These would multiply the design space available to the nanotechnologist, but would still be simulatable in tools like nanoengineer I guess. A protein folds itself but the problem is too hard to engineer and simulate. We may “knot a nanotube“ in a complex way leading to a complex 3D structure that acts as a starting point for building more complex structures. Now imagine if we could functionalise this structure. Such a structure could possibly be less sloppy than the ribosome. Maybe we can build structures higher up in the Klm hierarchy using knotted nanotubes with some right kind of molecules locked up in the right places. Just some wild thoughts!!!

- Sudarshan.P

* The idea of linking carbon nanotubes by means of knot-like connections between tori is one I haven’t seen before and is a physically sound concept.

* Fabrication of the tori, on the other hand, especially in any substantial quantity, is far out of reach of current technologies.

* I wouldn’t place any bets on space elevator applications until someone presents a design and analysis that answers the question of what happens when a fiber breaks. The first, unavoidable result is that the detensioned segments snap back at high speed (~ 1 km/s), aimed toward other highly-stressed fibers.

* With sufficiently long nanotubes, a low-shear-strength interface to a matrix works quite well. Only small portions near the ends are partly detensioned. Further, the shear strength could be increased (even into the covalent range) by chemical modification of a fraction of surface sites.

* The question of the strength of linkages of this sort is interesting. There would be some weakening, but with less loss of strength in the bundles than in the single-tube configurations, owing to the larger bend radius. Compressive forces between tubes would also be lessened.

* A computational study of the distribution of force and strain should be publishable. If you want to pursue this, I’d recommend finding a coauthor who is familiar with a system for doing calculations of this kind and has a good understanding of the limitations of the model.

It may be a bit inappropriate for me to expect you to evaluate the idea. But it may be interesting food for thought for the design of the CAD tools… from the point of view of how users may want to use your tools. And maybe who knows might tickle your neurons to attack the problem of bootstrapping mechano-synthesis in a new way! I do dream of seeing the idea land up on the gallery at nanorex some day.

Sudarshan.