Wednesday, January 24, 2007

Nanotech rolls on

There's a nice little paper about to appear online in Nature Nanotechnology (advance online publication, doi:10.1038/nnano.2006.210). Christian Joachim and his colleagues have made a molecule consisting of a two wheels 8 Å wide on an axle. The wheels are in fact three-bladed paddlewheels, which may rotate by a third of a turn when pushed with the tip of a scanning tunnelling microscope. This sounds rather like Jim Tour's nanocar, in which the wheels are fullerenes. That's altogether a more sophisticated contraption: a four-wheeler with a full chassis, shown in the picture above. But Jim could only infer rolling from the nature of the path that the cars took when pulled with the STM. It looked pretty persuasive to me, especially as tripod cars could only go in circles. But Christian's work has more direct proof of rolling. By looking closely at the way the two-wheeled molecule moves, he and his colleagues can distinguish between simple hopping between the grooves of the atomic corrugations on the metal surface, smooth pushing when the corrugation is very shallow, and jumps due to rotation of one wheel by 120 degrees. Only one wheel turns at a time, so in that case the molecule pivots as it is pushed.

Sunday, January 21, 2007

Water in biology

I have started a new blog called Water in Biology, which does what it says on the can. My hope is that it will act as a forum for presenting and discussing new research on the roles of water in the living cell. It seems that barely a week passes without something new and interesting coming out in this area, and I’m sure I’m seeing only a fraction of it. This will hopefully be a way of keeping track of what is out there, and hearing some informed opinions about it. It’s a controversial area, and I’m well aware that there are risks in setting this up: the behaviour of water in biological systems has been something of a magnet for weird and often not so wonderful theories. I hope to keep them at a distance. No doubt it will seem terribly elitist to the likes of the homeopathy enthusiast who expressed such disappointment on about my book on Paracelsus, but I’d respectfully suggest that if homeopathy, Jacques Benveniste’s digital biology, or Masaru Emoto are your bag, this site might not be for you. (I’m sure there are lots of others that are.)

Wednesday, January 17, 2007

Dark matter, memories and chimeras
[This is my Lab Report column for the forthcoming (February) issue of Prospect.]

Cosmic bones
The universe has had its first X-ray, and the skeleton looks much as expected. It is made of mysterious dark matter, which accounts for five sixths of the matter in the universe. It has been mapped out in a project called the Cosmic Evolution Survey (Cosmos), which pieced together more than 500 images from the Hubble space telescope to trace out the fine filaments of dark matter threading through deep space. These act like flypaper for ordinary matter, concentrating it into stars and galaxies.

In effect, Cosmos has revealed the hidden framework behind the entire visible world. Among other things, it’s another reason to be thankful that Nasa was persuaded not to leave the ageing Hubble to decay, rather than risk another shuttle-borne service mission.

Dark matter can’t be seen directly—that’s why it is dark—and isn’t made from any known subatomic particles. But we know it’s there because of the gravitational tug it exerts on visible matter. It was first postulated to explain why galaxies don’t fly apart as they rotate—but not everyone was convinced it existed until a study last year revealed it apparently balancing an otherwise lopsided spread of visible matter in a collision between two galaxies.

The Cosmos team mapped the distribution of dark matter over a big chunk of the universe by looking at the way it bends light from very distant galaxies behind it. The densest clumps of dark matter, where filaments intersect, mostly match the positions of visible galaxies and gas, as they should. But there are a few regions of dark matter without visible matter and vice versa—bones without flesh, and flesh without bones, so to speak. That wasn’t predicted and can’t easily be explained. Might there be entire galaxies made only of dark matter? It seems more likely that the discrepancies are just errors in the data, which depends on a tour-de-force of astronomical measurement.

It remains something of a scandal that we know nearly nothing about the stuff these cosmic bones are made from (our ignorance of the “dark energy” that outweighs dark matter by a factor of three is even more profound). But that’s modern cosmology for you: the harder you look, the more puzzling it gets.

Forgetful computers
Another well-hidden scandal lies in the guts of modern computers. Imagine that your piano had to be retuned from scratch every time you wanted to play, or your television set had to be retuned to the broadcast frequencies whenever it was switched on. This is the way computers work: you turn on and wait for minutes as the working memory, or random access memory (RAM), relearns how to work by reading the “manual” held on the hard disk. Actually, it’s even worse. The RAM then forgets everything you tell it within a microsecond—or would do if its memory cells were not refreshed thousands of times a second. That’s why, if the power turns off unexpectedly, all your unsaved data is lost.
It’s also why the RAM sucks all the juice from laptop batteries within hours.

All this could be changed with a technology that is already commercially available but still too expensive to go into your computer. Non-volatile RAM is a memory that, once loaded with data, holds onto it indefinitely without needing any power. With such a memory, a computer wouldn’t need a hard disk at all, and would be ready to use the moment you switched on. Various forms of non-volatile RAM are being developed, the most advanced being ferroelectric RAM (FeRAM), in which the memory elements are a little like magnets with poles oriented by electric rather than magnetic fields.

FeRAM is big in east Asia—the leaders include Samsung, Matsushita and Fujitsu. There’s even a small FeRAM in the Sony Playstation 2. But big, computer-style memories remain too expensive to make this way, and so FeRAM is currently relegated to low-tech applications such as smart cards for Japanese railways. They can be read from six inches away, however, so you don’t even need to get the card out of your bag.

Dr Moreau visions
The UK Human Fertilisation and Embryo Authority recently concluded that “there needs to be a full and proper public debate and consultation” about whether it should licence the creation of animal-human chimeric cells, for example with human DNA housed by nonhuman cells. The HFEA wisely avoided a snap decision in response to the opposition to such cells in a government white paper. The issue, as it says, is “far from black and white.” But the white paper’s recommendations seem to suffer from visions of Dr Moreau. Xenotransplants of animal organs and tissues into human patients have been happening for years, but the popular idea, peddled by the human genome project, that genes represent the sacred core of humanity has apparently created a sense that they are untouchable.

While there are ethical difficulties with chimeric cells, the medical benefits could be huge. Stem cells can be cultivated from embryos, but human eggs are hard to acquire for this. Animal eggs carrying human DNA would be more readily available, and could usher in all kinds of stem-cell therapies. The stem cells wouldn’t be “half-animal” in any meaningful sense, any more than a molecule taken from a human cell is different from an identical one taken from an animal. The HFEA aims to complete its consultation in the autumn. UK legislation in this area has been sensible and permissive so far, but stem-cell scientists are nervous that this time the yuck factor is about to kick in.

Tuesday, January 16, 2007

You couldn't make it up

"School chemistry ban for teen tartan terrorist". There I was all ready to sink my teeth into this great headline from the Scottish tabloid the Daily Record, only to discover that they made it up.

The story is that the "tartan terrorist" 16-year-old Jamie Hoggan, who has been placed in Polmont young offenders' unit for firebombing council offices in Alloa last August, was being denied chemistry and physics lessons while being sent his homework by his school, the Alloa Academy. Young Jamie apparently wants to "drive the English out of Scotland" (I know, but this is a 16-year-old lad who has presumably watched Braveheart thinking it was history). According to the Daily Record, a "source" said that "science was out of the question while he was in Polmont because of what went before." The notion that one can't make bombs without GCSE chemistry, and that one becomes an expert bomb-maker with it, was so silly that this seemed to demand some comment. (And what was the problem with physics? That he'd nuke the council instead?)

But it was all fabrication. A tired-sounding head at the Academy told me the story was "complete rubbish", before referring me to a nice woman at Corporate Affairs who said she only held back from writing to the Record to, er, set the record straight, by the understandable fear that the newspaper would then run the headline "School chemistry lessons for teen tartan terrorist". A victory for common sense, then, and a big boo to silly tabloids. And Jamie apparently hopes to become a forensic scientist – good luck to him!