Archive for July, 2006

A brief update

Friday, July 28th, 2006

My frequency of posting has gone down in the last couple of weeks due to a combination of excessive busy-ness and a not wholly successful attempt to catch up with stuff before going on holiday. Here’s a brief overview of some of the things I would have written about if I’d had more time.

The Nanotechnology Engagement Group (which I chair) met last week to sketch out some of the directions of its second policy report, informed in part by an excellent workshop – Terms of Engagement – held in London a few weeks ago. The workshop brought together policy-makers, practitioners of public engagement, members of the public who had been involved in public engagement events about nanotechnology, and scientists, to explore the different expectations and aspirations these different actors have, and the tensions that arise when these expectations aren’t compatible.

The UK government’s funding body for the physical sciences, EPSRC, held a town meeting to discuss its new draft nanotechnology strategy last week. About 50 of the UKs leading nanoscientists attended; To summarise the mood of the meeting, people were pleased that EPSRC was drawing up a strategy, but they thought that the tentative plan was not nearly ambitious enough. EPSRC and its Strategic Working Group on Nanotechnology (of which I am a member) will be revising the draft strategy in line with these comments and the result should be presented to EPSRC Council for approval in October.

The last two issues of Nature have much to interest the nanotechnologist. Nanotubes unwrapped introduces the idea of using exfoliated graphite as a reinforcing material in composites; this should produce many of the advantages that people hope for in nanotube composites (but which have not yet so far fully materialised) at much lower cost. Spintronics at the atomic level describes a very elegant experiment in which a single manganese atom is introduced as a substitutional dopant on a gallium arsenide surface using a scanning tunnelling microscope, to probe its magnetic interactions with the surroundings. This week’s issue also includes a very interesting set of review articles about microfluidics, including pieces by George Whitesides and Harold Craighead, to which there is free access.

Rob Freitas has put together a website for his Nanofactory collaboration. Having complained on this blog before that my own critique of MNT proposals has been ignored by MNT proponents, it’s only fair for me to recognise that this site has a section about technical challenges which explicitly acknowledges such critiques with these positive words:
“This list, which is almost certainly incomplete, parallels and incorporates the written concerns expressed in thoughtful commentaries by Philip Moriarty in 2005 and Richard Jones in 2006. We welcome these critiques and would encourage additional constructive commentary – and suggestions for additional technical challenges that we may have overlooked – along similar lines by others.”

Finally, in a not totally unrelated development, the UKs funding council, EPSRC, will be running an Ideas Factory on the subject of Matter compilation via molecular manufacturing: reconstructing the wheel. The way this program works is that participants spend a week generating new ideas and collaborations, and at the end of it £1.45 million funding is guaranteed for the best proposals. I’ve been asked to act as the director of this activity, which should take place early in the New Year.

A cross-section of science at the Royal Society

Thursday, July 13th, 2006

I’ve been attending the New Fellows seminar at the Royal Society, the UK’s national academy of science. This is the occasion for the 44 new fellows that are elected each year (one of whom, this year, was me) to give a brief talk about their research. The resulting seminar is a fascinating snapshot of the whole breadth of current science and technology, of a kind that one rarely sees in today’s world of science specialization. Here are some impressions of the first day.

Biology is strongly represented, with a cluster of talks on various aspects of cell signaling, ranging from the details by which signaling molecules are switched on and off, to the ways stem cells are regulated. A revealing talk showed how electron microscopy could unravel the mechanism by which the remarkable machines that ensure proteins fold correctly – chaperonins – work. From environmental and earth science we had talks on the effects on our environment both of the forces of nature – in the shape of the relationship between long term climate change and variations in the sun’s activity – and of the effects of man, through the impact of our industrial society on atmospheric chemistry. In physics, there was a spread from the most pure aspects of the subject (how to measure the spin of a black hole) to the applied and commercially important (the molecular beam epitaxy technique that underlies much of current semiconductor nanotechnology). One thing that comes out very strongly from the talks are the unexpected unifying threads that run through what appear on the face of it to be very different pieces of science. Ideas from statistical mechanics, like entropy, are obviously important for understanding self-assembly in soft matter, but they also cropped up in talks about signal processing in the brain and in modelling the growth of cities.

The important relationship between science and society was highlighted in two contrasting talks about the application of science to solve problems in the developing world. In one, the talk was at an abstract level, highlighting the problems of governance and economics in Africa that made it difficult to apply existing science to solve pressing problems. These abstract ideas were made very concrete in a fascinating talk about the development of new combination therapies to overcome the problems caused by drug-resistance in malaria. The foundation of these therapies is a new anti-malarial, artemesinin, recently discovered by Chinese scientists on the basis of a remedy from traditional chinese herbal medicine. Now that effective remedies are available, the problems to overcome are the social, economic and political barriers that prevent them from being universally available.

A round-up of nano-blogs

Friday, July 7th, 2006

To mark the growing popularity of science-based blogs, here’s a quick roundup of some blogs devoted to nanotechnology. Nanotechnology means many things to different people, and this diversity of points of view is reflected in the wide variety of perspectives on offer in the blogs.

From the point of view of business and the financial markets, TNTlog comes from Tim Harper, of the European consulting firm Cientifica. His posting frequency has dropped off recently, which is a pity, since this is a blog that manages to be both entertaining and well-informed, with a healthy scepticism about some of the wilder claims made on behalf of the “nanotechnology industry”. The web-portal nanotechnology.com hosts a contrasting pair of blogs. blog | nano, by Darrell Brookstein, is at the shriller end of the nanobusiness spectrum, while Steve Edwards’s blog combines commentary on nano financial markets with the odd extract from his (rather good) book – The Nanotech Pioneers.

Among blogs written by academics, there are those that come from scientists working inside the field, and some from social scientists whose interests run more towards the social issues surrounding nanotechnology. In the first category we have Nanoscale Views, by academic nanophysicist Doug Natelson. This combines capsule reviews of new condensed matter preprints and conference reports with more general observations about life as a junior faculty, and is at quite a high technical level. Martyn Amos is a computer scientist; his blog covers issues such as synthetic biology and chemical computing. The authors of Molecular Torch seem to be keen to keep their identities quiet, but from what they cover I’m guessing they work in the field of nanochemistry, with a particular interest in quantum dots. If you want to know what Soft Machines is about, just look around.

From the social science side of things, David Berube’s Nanohype casts a sceptical eye on the scene, leavening fairly detailed commentary on various reports and conferences with his enjoyably acerbic humour. Nano|Public, Dietram Scheufele, similarly covers public engagement issues from an academic point of view. Nanotechbuzz by George Elvin, is more general in its coverage, which reflects the interests of its author, an architecture professor with interest the relationship between nanotechnology and design.

A couple of blogs reflect the views of those interested in Drexler’s vision of molecular nanotechnology. The current market leader in the faith-based end of this space is Responsible Nanotechnology, from the Center for Responsible Nanotechnology, aka Mike Treder and Chris Phoenix. This pair have the most impressive output in terms of sheer volume. Their analysis is predicated on the unsupported assertion that desktop nanofactories could be with us in 10-15 years; any dissent from this view is met, not with rational argument, but with accusations of bad faith or scientific fraud. Nanodot, from the Foresight Nanotech Institute’s Christine Peterson, represents the more acceptable face of Drexlerism, combining reporting on current nanoscience developments and commentary about social and economic issues, with discussion of longer-ranged prospects, albeit in a framework of thorough-going technological determinism.

Finally, we have a couple of blogs written by professional writers. Howard Lovy’s Nanobot was a useful source of nano- commentary, particularly strong on charting the influence of nanotechnology on popular culture, before Howard’s move to the darkside of public relations led to a quiet period. Nanobot has recently gently restarted. A very welcome newcomer is homunculus from my favourite science writer, Philip Ball. The scope of homunculus goes well beyond nanotechnology, covering aspects of chemistry and physics ranging from the application of statistical mechanics to financial markets to the historical links between chemistry and fine arts. His most recent post contains much of the useful background information that didn’t make it into his recent news piece for Nature about the potential neurotoxicity of nanoscale titania.

My apologies to anyone I’ve missed out.

Soft soaping hard matter

Monday, July 3rd, 2006

Self-assembly is an elegant and scalable way of making complex nanoscale structures. But it only works for soft matter – the archetypal self-assembling systems are bars of soap and pots of hair gel; they’re soft because the energies that cause their components to stick together are comparable with the energies of thermal agitation. Is there a way of overcoming this limitation, and using self-assembly to make complex nanoscale structures from hard materials, like ceramics and (inorganic) semiconductors? There is – one can use the soft structure to template the synthesis of the harder material, so that the hard material takes up the intricate structure of the soft, self-assembled structure one starts with. It’s possible to use this templating technique to make glass-like materials, using so-called sol-gel chemistry. But up to now it’s not been possible to make templated, nanostructured elemental semiconductors like silicon or germanium. Two papers in this week’s Nature (Editor’s summary, with links to full articles and commentary, for which subscription is required) report the achievement of this goal for the case of germanium.

To do this, the first requirement is a chemistry for synthesising germanium that works in solution at moderate temperatures. No such chemistry exists that uses water, so another solvent system is needed, together with a compatible surfactant that self-assembles in this solvent. The two papers manage to overcome these barriers in ways that are different in detail, but similar in principle. Sarah Tolbert’s group, from UCLA, uses ethylene diamine as the solvent and the cationic surfactant CTEAB (a very similar molecule to that found in some mild domestic disinfectants) to form the self-assembled nanostructures, which in their case took the form of hexagonally packed rods. Mercouri Kanatzidis’s group at Michigan State used formamide as the solvent and a somewhat different cationic surfactant (EMBHEAB). Both groups used variants of the so-called Zintl salts, in which germanium is combined with a reactive metal like potassium or magnesium.

In both cases the germanium is disordered on the atomic scale, but with good long-ranged order on the larger length-scales, that reflects the relative perfection of the original self-assembled soapy structure. The UCLA group manage to remove the surfactant, leaving a nicely hydrogen-terminated germanium. The Michigan State group were unable to get rid of their surfactant, but on the positive side the structure they formed was the very beautiful and potentially useful gyroid phase, a high-symmetry structure (see the picture) in which both the material and the pores are continuous. Immediate uses of these structures follow from the fact that the optoelectronic properties of the material are strongly affected by its nanostructured form, and can be further changed by adsorption of matter on the semiconductor’s surfaces, offering potential sensor applications.

the gyroid phase

The gyroid phase, a cubic bicontinuous structure formed by some self-assembling surfactant systems. This structure has now been formed from elemental germanium using a templating process.