Comments on: Do materials even have genomes?

By: MattC

MattC — Sun, 09 Dec 2012 11:59:43 +0000

My understanding comes very much from the atomic side of things but I think even there a materials genome is still a way away, as James points out in general.
The idea of a genome relies on the concept that composition dictates properties in some fundamental sense. For biological structures (I’m no biologist so I may be wrong), although composition in an average sense doesn’t directly dictate properties, a protein’s composition does seem to fairly uniquely determine a protein’s structure. Firstly, ‘composition’ for a protein is an ordered list – where as a stoichiometry is very much non-ordered. Secondly, evolution has selected for proteins that can be relied on to form a single kind of structure*. Thirdly, the synthetic conditions are both favourable, e.g. perhaps there are chaperone molecules aiding the formation of the correct folded form, and fixed, i.e. you don’t need to consider anything other than those inside the cell that the protein comes from (after all, we aren’t making de-novo proteins, just tweaking those that already exist).

For materials, this assumption that composition->structure->properties cannot be made as forcefully. After all, for many inorganic materials, even composition is something that can require great effort to be designed.

The original materials (genome) project, http://www.materialsproject.org, I think has some interest to it, despite neglecting most of the issues you deal with above. I think the idea that we can assess a-priori all simple ternary inorganic compounds for their viability in various applications is pretty remarkable. It is not a complete solution to this materials genome problem, but it does make a step along the right path.

*I’m sure exceptions exist, but they are just that.

By: Richard Jones

Richard Jones — Wed, 14 Nov 2012 09:21:54 +0000

James, the analogies between inorganic and biological materials are very interesting, but they’re revealing as much in their differences as in their similarities. Both are (almost always) non-equilibrium structures, but inorganic ones are usually generated by taking a system a long way from equilibrium, allowing it to progress towards equilibrium and arresting it before it gets there, while biological ones are produced by keeping the system constantly away from equilibrium by a constant driving input of free energy. But they do share the hierarchy problem, which as you rightly say leads to a serious (but interesting) problem of description.

By: James

James — Sun, 28 Oct 2012 18:06:12 +0000

First, it is encouraging to see a lucid commentary on the MGI. I’ve been troubled by this since announcement too.

Second, of course, materials don’t have genomes–you can take a given chemical composition, say 1Si + 2O = SiO2, and depending how it is created and processed, derive a large number of different microstructures of various scales and defect content and character, and thereby with very different properties and resulting cost structure. However, that said, if one takes a specific initial set of constituents, and performs the same process sequence time after time on the starting set, one will arrive at the same microstructure and properties suite.

There are analogues between how biological and inorganic materials assemble. But before we take them too far, we need to find a common language to describe materials–something that captures all relevant scales from electronic bonding to microstructural. A great pile of diffractograms, chemical spectra and photomicrographs won’t do it. They need to be integrated across all modes. It’s a good problem. And when it is solved, we might actually start speaking intelligently about fundamental data units that describe materials uniquely, and building generically useful models of development and behavior.

By: David

David — Tue, 23 Oct 2012 16:14:37 +0000

Like in the old nanotechnology debate, it’s all about what (composable) abstractions physics allows us to make, and of course, finding them. Too much focus on the engineer hat, and not enough on the physicist hat, and you get leaky abstractions that just don’t work.