Archive for February, 2012

Evidence for Antimatter Anomaly Mounts

Published in ScienceNOW, 29 Feb 2012

The big bang created a lot of matter—along with the same amount of antimatter, which wiped out everything and brought the universe to an untimely end. That’s what accepted theoretical physics tell us—though things clearly didn’t work out that way. Now, results from a U.S. particle smasher are providing new evidence for a subtle difference in the properties of matter and antimatter that may explain how the early universe survived.

The first evidence of a difference between matter and antimatter was found in the 1960s in the decay of particles called neutral kaons, which led to the awarding of a Nobel Prize in physics. In 2001, accelerators in the United States and Japan found more evidence for a difference in particles called B mesons. Then last year at CERN’s Large Hadron Collider (LHC) near Geneva, Switzerland, evidence was found in a third system, D mesons, but there wasn’t enough data to rule out a statistical fluke. The new results—which come from the Collider Detector at Fermilab (CDF) experiment near Chicago—are still not conclusive evidence, but they bring the chances of a fluke down to about one in 10,000. “I’m sure in a few days everyone in the field will feel much more confident that this is actually real,” says Giovanni Punzi, spokesperson of the CDF experiment. [...]

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Lab study could aid inkjet printing

Published in Physics World, 22 Feb 2012

A filament of liquid squirted from a nozzle will sometimes contract into a single drop and other times break up into many segments. Now, researchers in the UK have mapped the parameters that will lead a filament to break up, and they believe that this knowledge could help in the design of inkjet printers.

Inkjet printing requires single drops of ink to be deposited on paper, and for this reason engineers are keen to avoid conditions that would encourage ink filaments squirted from an inkjet nozzle to break up. Theory shows that there are several crucial parameters: the liquid’s density, viscosity and surface tension – all three of which can be grouped into a single “Ohnesorge number”. The other is the aspect ratio, which describes the filaments’ length in relation to diameter. In general, longer filaments with a high aspect ratio, and filaments with a small Ohnesorge number, are likely to break up. [...]

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DNA nanorobots seek and destroy disease

Published in Chemistry World, 17 Feb 2012

Researchers in the US have created a DNA-based nanorobot that can work its way through cell cultures, delivering cargo only at specific targets. The development could pave the way for programmable therapeutics, in which nanorobots would provide medical treatment only to certain types of cell or tissue.

The field of nanomachines has taken off in recent years, mostly thanks to so-called DNA origami. In this technique, DNA strands can be folded controllably into a structure, onto which different molecules can be attached. Researchers have already shown that structures built using DNA origami can perform basic robotic tasks, such as sensing, computation and targeting cells. But, says biophysicist Shawn Douglas at Harvard Medical School in Boston, Massachusetts, no one has ever combined these tasks to do something more sophisticated, such as cell-targeted cargo delivery. [...]

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Axions could solve lithium problem

Published in Physics World, 15 Feb 2012

For more than a decade, scientists have been aware that the theory used to explain how the lightest elements are created overestimates the overall amount of lithium-7 in the universe. Now, physicists in the US think the answer to this so-called lithium problem might lie in a hypothetical particle known as the axion – although many are not convinced.

The theory is called Big Bang nucleosynthesis and describes a stage early in the universe’s evolution when, at temperatures of thousands of degrees, protons and neutrons began to assemble into atomic nuclei and form the first light elements: deuterium, along with isotopes of helium and lithium. As temperatures dropped, nucleosynthesis drew to a close, and eventually electrons began to add themselves to the nuclei during a period called recombination. At this time, photons stopped scattering off charged particles and the universe became transparent. [...]

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Nanoparticles slow iron absorption in the gut

Published in Chemistry World, 12 Feb 2012

Nanoparticles used in food and pharmaceuticals could have unintended physiological effects. This is the suggestion of US researchers who have showed that polystyrene nanoparticles can affect the uptake of iron – an essential nutrient – in a model intestine.

Manmade fine particles, including nanoparticles, are now regularly used in food and pharmaceuticals – so regularly that a person in a developed country consumes as much as 100 trillion of them every day; mostly titanium dioxide, silicates and aluminosilicates found in food additives. As a result, scientists have been eager to investigate possible adverse health effects. A high reactivity thanks to their huge surface area, and an ability to pass through cell membranes, are just two areas of concern.  [...]

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Listening with a ‘quantum ear’

Published in Physics World, 9 Feb 2012

Physicists are very good at making measurements with single photons of light. Soon, however, they may also be doing routine studies of single phonons – single quanta of sound. That is the claim of physicists in Sweden and Germany, who say they have detected acoustic waves that are so weak they are – almost – at the quantum limit.

Recent years have seen a great effort to work with mechanical oscillations in the quantum regime. In such a regime, a mechanical device would be able to both emit and detect single phonons – just as optoelectronic devices are already able to emit and detect single photons. In 2010 a group at the University of California, Santa Barbara, US, demonstrated that it could create single phonons using a cryogenically cooled mechanical oscillator, thereby taking the first step on the quantum road. [...]

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