Issue no. 28, 2006
Published: Aug 25, 2006 |
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 Dark matter reveals itself 100m light years away |
| Top hydrogen-storing polymer revealed |
| Scientists make silver transparent |
| Strategic tree planting could save water in dry areas |
| Artificial muscles light up TVs |
| Invention: Jellyfish injections |
| Remote burglar-bamboozler |
| Revealed: world's oldest computer |
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| Dark matter reveals itself 100m light years away |
Scientists at the University of Arizona believe they have found the
first direct evidence of mysterious 'dark matter' - invisible material
thought to make up 22 per cent of the universe.
Observations of two colliding galaxy clusters 100 million light years
away showed ordinary matter and dark matter being wrenched apart. Hot
gas produced by the 6.2 million miles-per-hour collision was slowed by a
drag force, similar to air resistance.
But dark matter particles were not affected the same way, since they do
not interact with ordinary matter except through gravity. This produced
a separation of normal and dark matter, which raced ahead of the
bullet-shaped hot cloud. Astronomers used a technique called
'gravitational lensing' which measures the way light is bent by the
distortion of space caused by gravity.
No-one knows what dark matter is made of, but without it the universe
could not exist as it does and there would be no life on Earth. Dark
matter is thought to act as a 'glue' holding galaxies together and
creating order in the cosmos. |
| The Scotsman / Astrophysical Journal Letters
Aug 23, 2006 |
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| Top hydrogen-storing polymer revealed |
A series of computer simulations has identified a polymer material with
a very large capacity for storing hydrogen that could be exploited in
fuel cells. Scientists at Seoul National University in South Korea have
discovered that polyacetylene with titanium atoms attached to the
polymer chain can hold 63 kilograms of hydrogen per cubic metre - more
than any other similar material in their survey.
A low-cost, high-capacity hydrogen-storage medium is essential for the
commercialisation of hydrogen fuel-cell technologies. Researchers had
previously looked at carbon nanotubes, hydrogen-clathrate-hydrates and
other nanostructured materials as ways of storing hydrogen, but they
only work at low temperatures or high pressures. Now, the researchers
have shown that polymers covered with metal atoms can store a
significant amount of hydrogen under more practical working conditions.
They found that up to five hydrogen molecules can be attached to each
titanium atom in a particular form of polyacetylene, allowing the
material to reversibly store 7.6 wt% of hydrogen, or 63 kilograms per
cubic metre under practical working conditions. This value is higher
than a target of 45 kilograms per cubic metre that the US Department of
Energy said should be reached by 2010. |
| PhysicsWeb / Phys. Rev. Lett.
Aug 24, 2006 |
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| Scientists make silver transparent |
Physicists at the University of Exeter, UK, have discovered that films
of silver - a normally opaque material - can be made highly transparent
by sandwiching them between zinc-selenide-coated glass blocks.
The researchers coated the surface of a silica prism with a film of zinc
sulphide 200 nm thick. They then clamped two such prisms together,
leaving a very thin air gap between them. When light of the correct
wavelength was used, it was found to pass through the sandwich with
about 85 per cent efficiency. This was not quite perfect transmission
because the zinc sulphide absorbs some light. They then replaced the air
gap with a 40-nm thick layer of silver, which was found to transmit
light with an efficiency as high as 35 per cent at certain wavelengths.
The researchers say their technique could be used to improve the
efficiency of a new generation of 'top emitting' OLEDs, whose
performance is limited by the light passing through a metal cathode. It
could also be used to improve semiconductor devices, where an analogous
quantum effect should be seen. Here, semiconductors could be layered
together to create a barrier through which a current could tunnel with
less loss. |
| Physicsweb / Phys. Rev. Lett.
Aug 22, 2006 |
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| Strategic tree planting could save water in dry areas |
Researchers say that planting trees in dry regions of the world could
make better use of scarce water resources increasingly threatened by
climate change. They warn, however, that although planting the right
species in the right areas could improve water efficiency, other species
could make the problem much worse.
The World Agroforestry Centre (ICRAF) findings, based on 20 years of
research in Kenya, were announced at the World Water Week meeting in
Stockholm on 22 August.
Many African countries have large plantations of pines or eucalyptus.
But ICRAF scientists advise against planting these fast-growing
evergreen trees because they need a lot of water. Instead, they
recommend planting deciduous trees in integrated 'tree-crop' systems, in
which agriculture and forestry are practised on a single piece of land.
Such trees shed their leaves for up to six months of the year, nearly
halving the amount of water they need. This enables them to cope with
long dry spells and also means they will not compete with crops for
water. ICRAF recommends different tree species for specific regions. |
| SciDev
Aug 24, 2006 |
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| Artificial muscles light up TVs |
Arrays of thousands of tiny 'super prisms' controlled by robotic muscles
could bring real colour to TV screens for the first time. The devices,
known as electrically tenable diffraction gratings, have been built by
researchers at the Swiss Federal Institute of Technology in Zurich,
Switzerland. They manipulate light to reproduce the full spectrum of
colours on screen, impossible using existing technology.
Existing screen technology, such as TV cathode ray tubes, LCDs and
plasma screens, reproduce colours using three lighting elements coloured
red, green and blue. Other colours are created by combining the primary
colours. The new system is not limited to the three-colour system but
uses the full spectrum of colours visible to the naked eye.
The researchers have built a diffraction grating, a slotted grate like a
miniature Venetian blind, made of a flexible polymer, normally used for
robotic muscles. When pure white light hits the grate it is split into
the full spectrum of colours. By applying different voltages to the
muscle, the grate expands and contracts, causing the fan of split light
to shift from side to side. Different colours can then be isolated from
the spectrum using a tiny hole fixed in front of the grate. Adjusting
the voltage across the muscle allows different parts of the colour
spectrum to be lined up with the hole. |
| BBC News / Optics Letters
Aug 21, 2006 |
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| Invention: Jellyfish injections |
The stinging cells of jellyfish could soon be used to inject drugs and
apply tattoos, according to inventors working for US company NanoCyte.
Jellyfish and other Cnidaria have stinging cells called cnidocysts.
These shoot a tiny hollow thread, at incredibly high speed, into
anything that touches a 'trigger' near the cell's opening, and then pump
toxin through the thread into the target. The inventors propose
extracting the toxin without killing or triggering the cells, simply by
incubating them for a few minutes at around 70°C. The empty cells could
then be soaked in whatever chemical is to be injected, they say.
The cells would be applied to a patient's skin in a patch and then
pressure combined with a few low-voltage electric pulses should trigger
the cells to fire. They would shoot out their tubules, penetrate the
skin and inject the new chemical. Because there is no toxin, the
injection should be very quick and painless, and the threads would be
extracted once the patch is removed. The inventors believe the technique
could be used to treating skin complaints, or deliver drugs. |
| New Scientist
Aug 21, 2006 |
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| Remote burglar-bamboozler |
Burglars cannot always be fooled by a simple timer that activates lights
in a house while someone is away. But a new type of infrared remote
control promises to provide better protection by switching from normal
use to a special 'burglar confusion mode'.
The cunning device, proposed by Philips, would switch audio and video
equipment on and off using a built-in timer to simulate the presence of
a person in a room.
In the morning, for example, the remote would tune a radio to a news
station and select tracks from a pre-recorded CD containing household
sounds like clattering dishes and vacuum cleaning. Later that day, the
remote would tune the TV to a daytime channel and in the evening it
would fire up a DVD movie while also dimming the living room lights. The
switching sequence would follow the same general pattern every day but
change at weekends, Philips says. |
| New Scientists
Aug 21, 2006 |
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| Revealed: world's oldest computer |
It looks like a heap of rubbish, feels like flaky pastry and has been
linked to aliens. For decades, scientists have puzzled over the complex
collection of cogs, wheels and dials seen as the most sophisticated
object from antiquity. But 102 years after the discovery of the
calcium-encrusted bronze mechanism on the ocean floor, hidden
inscriptions show that it is the world's oldest computer, used to map
the motions of the sun, moon and planets.
Known as the Antikythera mechanism and made before the birth of Christ,
the instrument was found by sponge divers amid the wreckage of a cargo
ship that sunk off the tiny island of Antikythera in 80BC. To date, no
other appears to have survived. For years scholars had surmised that the
object was an astronomical showpiece, navigational instrument or rich
man's toy. Cicero described the device as being for 'after-dinner
entertainment'.
But many experts say it could change how the history of science is
written. 'In many ways, it was the first analogue computer,' said
Professor Theodosios Tassios of the National Technical University of
Athens. 'It will change the way we look at the ancients' technological
achievements.' See: http://www.antikythera-mechanism.gr |
| The Guardian
Aug 20, 2006 |
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