Water purifier harnesses green chemistry

Chemistry WorldJon Cartwright

Published in Chemistry World, 24 May 2011

Chemists in the US have created a water purifier that can remove organic toxins without the addition of acids or other harmful chemicals. The device, which uses two highly porous membranes to generate purifying hydroxyl radicals, could help to provide clean drinking water for the developed and developing world.

Providing safe drinking water is one of the top priorities for scientists working on humanitarian projects, and one particular problem is the contamination of groundwater aquifers with toxic organic compounds. Even in the US, two-thirds of all hazardous waste sites are contaminated with trichloroethylene (TCE), which is potentially carcinogenic. TCE, together with 2,4,6-trichlorophenol (TCP) – once used as a pesticide and fungicide – is responsible for drinking-water contamination in much of the world. […]

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Snake venom gets into the groove

Physics WorldJon Cartwright

Published in Physics World, 23 May 2011

If you are ever unlucky enough to have a snake sink its fangs into your leg, then you might take a second to marvel at the clever mechanism behind its venom delivery. Indeed, according to biophysicists in Germany and the US, many venomous reptiles do not inject their poison, as you might think. Instead, they rely on a toxic mix of surface tension and “tomato ketchup” physics. “Until we did, nobody had ever bothered about the question of why snake envenomation happens the way it does,” says team member Leo van Hemmen of the Technical University of Munich. […]

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Liquid crystals spot bacteria to order

Chemistry WorldJon Cartwright

Published in Chemistry World, 19 May 2011

Liquid crystals could one day be used as bio-sensors, detecting the presence of minute amounts of pathogens. That is the claim of a US group of researchers, who have demonstrated how a liquid crystal changes orientation in the presence of bacteria.

Unlike normal materials, liquid crystals have a distinct phase between the solid, ordered crystalline phase and the disordered liquid phase: the liquid-crystal phase. In this phase, the molecules of a liquid crystal try to become ordered. In a nematic liquid crystal like 5CB (4-pentyl-4′-cyanobiphenyl), for example, the molecules try to align lengthways.

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‘Homeless’ Planets May Be Common in Our Galaxy

ScienceJon Cartwright

Published in ScienceNOW, 18 May 2011

Our galaxy could be teeming with “homeless” planets, wandering the cosmos far from the solar systems of their birth, astronomers have found. The study could help clear up a long-running debate of whether free-floating planets really exist, and how common they are.

“The results are convincing enough that I suspect this paper will be cited for years to come as the best evidence of free-floating planets,” says Dimitri Veras, an astrophysicist at the University of Cambridge in the United Kingdom, who was not involved with the study. […]

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‘Chemical soldering’ heralds single molecule electronics

Chemistry WorldJon Cartwright

Published in Chemistry World, 12 May 2011

Scientists in Japan and Switzerland have demonstrated how to wire up single molecules with conductive nanowires. The technique, called chemical soldering, is a big step towards single molecule electronics.

Molecules have long been proposed as alternative circuit components. In 1974, IBM researchers Mark Ratner and Arieh Aviram described how a single molecule could pass current in just one direction, thereby acting as a diode, and since then various other components, such as switches and transistors, have been put forward. In theory, single molecule electronics would be smaller than their silicon counterparts, and may require less power. […]

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New radioisotope bodes well for cancer treatment

Chemistry WorldJon Cartwright

Published in Chemistry World, 11 May 2011

An international team of researchers has produced sizeable amounts of a new radioisotope, paving the way for its use in cancer therapy. The isotope, terbium-161, emits a number of low-energy electrons upon decay, which should make it useful for treating small tumours.

Radioisotopes are commonly used to treat cancer. Normally, an isotope is attached to a special ‘bioconjugate’ molecule – an antibody, for example – that preferentially binds to cancer cells, so that the isotope only destroys diseased areas. As the isotope decays it emits radiation which ionises the cells’ DNA, stalling the tumour’s growth. […]

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Intel enters the third dimension

NatureJon Cartwright

Published in Nature, 6 May 2011

This week, computer chip manufacturer Intel announced that it is preparing to enter a new dimension in transistors — literally. Known as Tri-Gate, its new transistor will be the first to go into mass production with a truly three-dimensional (3D) structure.

Intel says that the transistor will offer performance and efficiency benefits over 2D models when becomes production ready in a new range of microprocessors later this year. But with some industry analysts calling it a risky venture, Nature explores what the advantages are of 3D. […]

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Invisibility cloak offers a snug fit

Physics WorldJon Cartwright

Published in Physics World, Apr 28 2011

An invisibility cloak that is less than five times bigger than the object it conceals has been unveiled by physicists in Denmark and the UK. They say that their device, which they built using semiconductor manufacturing techniques, offers the smallest cloak size relative to cloaked area to date.

First developed in 2006, invisibility cloaks can hide an object from view by bending light around it. The effect is similar to how a star’s immense gravity can warp space–time so that passing light is forced to take a curved path. In invisibility cloaks, however, the path of light is altered not by gravity, but by specially engineered variations in the refractive index of the devices. […]

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Solar power without solar cells

Physics WorldJon Cartwright

Published in Physics World, 21 Apr 2011

Physicists in the US believe that it is possible to generate solar power without solar cells. Their “optical battery” idea, which would involve performing the energy conversion inside insulators rather than semiconductors, could make for a far cheaper alternative energy source than existing solar-cell technologies.

In conventional solar cells, electricity is generated by simple charge separation. The semiconductor absorbs a photon of sunlight, knocking a negative electron into the material’s conduction energy band and leaving a positive hole in its place. With these two charges separated, a voltage is produced from which power can be drawn. […]

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Polymer heals itself with a light touch

NatureJon Cartwright

Published in Nature, 20 Apr 2011

Cracked your mobile-phone display? In the future, the remedy might be as simple, and cheap, as shining some light on it.

That is according to Christoph Weder, a materials scientist at the University of Fribourg in Switzerland, and his colleagues, who have developed a type of rubbery plastic that ‘self heals’ when exposed to ultraviolet light. The material might one day be incorporated into varnish, paint or mobile-phone covers. […]

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