Archive for January, 2011

What Is a Galaxy?

Published in ScienceNOW, 27 Jan 2011

What exactly is a galaxy? Surprising as it may sound, astronomers don’t have an answer to this fundamental question. There’s no agreement on when a collection of stars stops being a cluster and starts being something more. Now, in an echo of the recent wrangling over Pluto’s status as a planet, a pair of astrophysicists from Australia and Germany want to start a debate on the issue—and they have even set up a Web site for people to cast their votes.

You might think a galaxy is simply a large group of stars, but just how many stars does it take? Astronomers tend to call five or so stars a “group” and a hundred or more a “cluster.” At some point, a cluster becomes a galaxy—the Oxford English Dictionary suggests “millions or billions” of stars is enough—but there has never been an official threshold. [...]

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Luminescence gives 2D pH images

Published in Chemistry World, 26 Jan 2011

Researchers in Germany have devised a safe method to image the pH of tissue in the human body. The method, which involves measuring the luminescence of injected dyes, could help physicians monitor wound healing and tumour growth.

pH is crucial in several bodily processes. During wound healing, disturbed layers of skin can affect the pH, which in turn affects the function of certain enzymes necessary for new tissue formation. With tumours, changes in pH are also a signal of changes in metabolism, or the onset of oxygen deficiency. Since pH can vary over a small area, physicians are keen to find ways to monitor the pH in the body in two dimensions. [...]

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Physicists craft Luneburg lens from silicon

Published in Physics World, 22 Jan 2010

Physicists in the UK have created a Luneburg lens – a lens able to focus light from all directions equally well – on a silicon chip. The device could one day find applications in on-chip Fourier optics, which are used by the telecoms industry to perform tasks from noise reduction to data compression.

Most practical lenses have aberrations, which means that their ability to focus light deteriorates when the incident light is off-axis. But in the Luneburg lens, proposed over 60 years ago, focusing is equally good wherever the light comes from. [...]

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Chemists separate water isomers

Published in Chemistry World, 21 Jan 2011

Nine years ago, Russian researchers sparked controversy when they claimed to have separated water into its two spin isomers. Now, chemists in Israel claim to have performed a similar feat using a different method, and suggest the outcome could deliver highly sensitive nuclear magnetic resonance (NMR) experiments.

Water molecules come in two spin isomers: one ‘ortho-water’ with the spins of the constituent hydrogen atoms parallel, and one ‘para-water’ with the hydrogen spins anti-parallel. The two isomers have subtly different properties that become important in diverse fields of science. In astrophysics, for example, the ratio between ortho- and para-water is used to determine temperatures in interstellar space, although the data are hard to interpret – partly because scientists have been unable to study either isomer on its own. [...]

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Modified protein binders give shortcut to drugs

Published in Chemistry World, 19 Jan 2011

Researchers in Sweden have found a way to boost the specificity of drugs and other protein binders. The method, which involves attaching polypeptides to the binders, could help reduce the work required to develop protein binders into safer drugs.

Almost all drugs are protein binders. They work by interacting with certain proteins so that the proteins’ functions are blocked or stimulated, depending on the effect required. Protein binders are also used in medical diagnostics, industrial protein purification and many other areas of biotechnology and bioanalytical research. [...]

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Heat engine may be world’s smallest

Published in Physics World, 16 Jan 2011

Physicists in the Netherlands have built a heat engine that might be the tiniest ever created. Based on “piezoresistive” silicon, and smaller than a typical biological cell, the engine could find applications in watch mechanisms or as a mechanical sensor.

Engines come in a variety of sizes. The smallest include biological engines such as the flagella that bacteria use for locomotion, which are driven by chemical reactions, or manmade electrostatic engines, which drive ions with electric fields. [...]

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Quantum communications boosted by solid memory devices

Published in Physics World, 12 Jan 2011

Two independent groups have demonstrated how a pair of entangled photons can transfer their entanglement to and from a solid – the process that should one day form the backbone of so-called quantum memories or repeaters. These devices would enable quantum communication systems to transmit information over larger distances, with significantly reduced degradation.

“While I was sceptical a few years ago that a useful quantum repeater or quantum network could be built, I am now very confident…that this goal can be achieved in the next five to ten years,” says Wolfgang Tittel of the University of Calgary, Canada, an author of one of the papers that appear in Nature today. [...]

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New molecule could propel rockets

Published in Chemistry World, 7 Jan 2011

The largest nitrogen oxide molecule discovered to date could function as a rocket propellant, according to chemists in Sweden who have synthesised it for the first time. Trinitramide, N(NO2)3, has a higher energy and density than other materials used to combust rocket fuel – but some researchers are doubtful it will ever be useable outside the lab.

‘The identification of trinitramide is clearly a great discovery and academically highly important,’ says Thomas Klapötke, an expert in energetic materials at the Ludwig-Maximilian University of Munich, Germany, who was not involved in the research. ‘As far as a possible application as an oxidiser for rocket propulsion is concerned, I have slight doubts.’ [...]

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Plasma jets key to enduring solar mystery

Published in Nature, 6 Jan 2011

It’s been a mystery for more than half a century: why, in the short distance from the Sun’s surface to its corona, or outer atmosphere, does the temperature leap from a few thousand to a few million degrees? The answer, researchers say, might lie in hot jets of plasma erupting from the Sun’s surface.

“It’s truly a breakthrough in the longstanding puzzle of how the corona gets so hot,” says Rob Rutten, a solar physics expert at Utrecht University in the Netherlands who was not involved with the work. “The jets behave like bullets shot upwards, causing hot coronal temperature fronts in front of them.” [...]

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Silk woven into transistors

Published in Chemistry World, 5 Jan 2011

Researchers in Sweden and Spain have created transistors woven from modified silk fibres. The breakthrough bodes well for a new generation of electronic circuits that can be incorporated into fabrics or inserted into biological environments.

Conventional electronics are printed onto hard substrates, but many researchers are looking at ways to offer, literally, more flexible applications. Some are developing methods to print directly onto fabrics, while others are examining how to make individual fibres into circuit components. [...]

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