Japanese team create next-gen DVD material
A Japanese research team has found a material that could be used to make a low-price disc with data storage capacity thousands of times greater than a DVD.
The material transforms from a black-colour metal state that conducts electricity into a brown semiconductor when hit by light, according to Professor Shin-ichi Ohkoshi, of the University of Tokyo.
The material, a new crystal form of titanium oxide, can switch back and forth between the metal and semiconductor states at room temperature when exposed to light, creating an effective on-off function for data storage.
It is “promising as a material for a next-generation optical storage device,” says Ohkoshi, who is lead author of the study appearing in the journal Nature Chemistry.
A material that changes colour with light can be used in storage devices as colours reflect light differently to contain different information.
His team has succeeded in creating the material in particles measuring between 5 and 20 nanometres in diameter.
If the smallest particle is used, the new disc could hold more than 1000 times as much information as a Blu-ray disc, provided that matching data-writing and reading equipment are developed.
A single-layer Blu-ray disc can hold five times as much data as a conventional DVD.
The disc would also be cheaper. Titanium oxide’s market price is about one-hundredth of the rare alloy germanium-antimony-tellurium, which is currently used in rewritable Blu-ray discs and DVDs, says Ohkoshi.
“You don’t have to worry about procuring rare metals. Titanium oxide is cheap and safe, already being used in many products ranging from face powder to white paint,” he says.
Ohkoshi says it is not known when a disc with this material would be manufactured and put to practical use, adding that he would start talks with private-sector companies for commercialisation.
Reference Link
http://www.abc.net.au/science/articles/2010/05/25/2908718.htm?site=science&topic=latest
Courtesy
ABC
Artificial swallowtail butterfly reveals flight secrets
In a bid to find out how a butterfly takes to the air, researchers have built their own artificial version.
They have created a model swallowtail butterfly that can fly just like the real thing.
Swallowtails have large, slow-beating wings that means they fly unlike other butterflies.
Despite these limitations, the model insect proves that swallowtails still achieve forward flight with simple flapping motions, say the researchers.
Details of the artificial butterfly are presented in the journal Bioinspiration & Biomimetics, published by the Institute of Physics.
Undulating movements
Swallowtail butterflies have particularly large wings for their body size, and flap them relatively infrequently.
They are also unique among flying insects because their fore wings partly overlap their hind wings.
The lines show an undulating body motion
Because their two sets of wings effectively flap as one, that in theory gives them little control over the aerodynamic forces on their body.
That means their wings are limited to a basic flapping flight, and their bodies are forced to undulate up and down as they fly, say researchers Dr Hiroto Tanaka from Harvard University in Cambridge, Massachusetts, US and Dr Isao Shimoyama from the University of Tokyo, Japan.
But this has been impossible to check in real butterflies, because of the complexity of measuring the various forces acting on their wings and body.
Ornithopter arrives
So Drs Tanaka and Shimoyama decided to build an artificial swallowtail, dubbed an “ornithopter”.
The body is built from balsa wood, and the wings powered by a wire crank driven by a rubber band.
The artificial butterfly up close
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The researchers made artificial wings from a thin film of polymer, fabricating them with plastic veins mimicking those of an actual swallowtail butterfly.
That emulated the stiffness distribution of an actual wing.
Overall, the model is the same size and weight as a real swallowtail.
What is more, it can fly forwards just as a real butterfly.
Filming the robot butterfly in high speed helped the researchers calculate the forces acting on its wings and body.
Just as a real swallowtail would, the robot’s body undulated up and down in flight.
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SOURCES
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This confirmed that the up-down motion of the butterfly’s body is caused by the vertical aerodynamic force of its flapping wings.
However, it also confirms that swallowtails need veins on their wings to achieve stable flight, and do not need to continually adjust them as many others insects do.
Reference Link
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8694000/8694666.stm
Courtesy
BBC News
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