Issue no. 32, 2008
Published: Oct 17, 2008 |
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 Computer circuit builds itself |
| 'Stamp' method brings bendy, transparent solar cells |
| Success for plants' pest control |
| Newly discovered fungus strips pollutants from oil |
| Gecko-like glue is said to be stickiest yet |
| Giant lens could clean up dusty moon sites |
| Monkeys move paralysed muscles with their minds |
| 'Transparent cockpit' removes car blind spots |
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| Computer circuit builds itself |
A team of physicists at Philips Research Laboratories in Eindhoven, the
Netherlands has developed an integrated circuit that can build itself.
The work is an important step towards its ultimate goal - a
self-assembling computer.
To make a circuit that is truly self-assembling, physicists would need
to get insulators, conducting electrodes and semiconductor transistors
to all link to each other automatically - something that is still a long
way away. But the Philips team has made an important step. They took a
long organic molecule with mobile electrons, called quinquethiophene,
that behaves like a semiconductor and attached it to a long carbon chain
with a silicon group at the end, which acts as an anchor.
The researchers then dunked a circuit board with preprinted electrodes
into a solution of their new molecules. The molecules hooked on to an
insulating layer between the electrodes, forming bridges from one
electrode to the next. It took billions to make the connection, but they
were tightly packed enough that a current could flow across them. |
| Nature
Oct 15, 2008 |
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| 'Stamp' method brings bendy, transparent solar cells |
Imagine solar cells that are flexible enough to be rolled up like a
sheet of paper or so transparent that they can be hung over a window.
Such solar cells are a step closer now that researchers at the
University of Illinois and Northwestern University have devised a new
method for printing thin wafers of silicon onto many other types of
material.
They liken their method to the way a rubber stamp transfers ink from a
pad to paper. First they etch a striped pattern onto a wafer of
crystalline-silicon (the 'pad') before lifting the resulting segments
(the 'ink') with a soft piece of polymer (the 'stamp'). Then they push
the polymer onto the desired substrate (the 'paper') to print on the
segments. Finally they evaporate metal onto the back of the material and
etch it to leave electrodes running down the sides.
The benefit of this stamp method is that a wide variety of substrate
materials, including flexible plastics, can be used. In tests, the new
cells had a solar-energy conversion efficiency of 7.2% - significantly
under commercial devices, which operate at about 18% - though were
flexible enough to be rolled around a pencil. Another advantage of the
US team's method is that the cells can be printed thinly or in sparse
arrays so that they are partially transparent, which means they could,
for example, be fixed over windows. |
| Physics World / Nature Materials
Oct 09, 2008 |
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| Success for plants' pest control |
Researchers at Lancaster University have developed a potential new
method of making plants significantly more resistant to pests. They say
their method could greatly reduce pesticide use.
Until now attempts at creating pest- resistant crops involved GM
technology. This method uses a chemical that is naturally produced by
plants - jasmonic acid. Researchers have found that plants grown from
seeds first dipped in the acid are considerably more resistant to pests.
The effect is to boost the plant's own defences.
The best results were on tomato plants, where attacks by Red Spider
Mites were reduced by 80%, aphid attack was reduced by 60% and
caterpillar damage was down by a third. Good results were also obtained
on maize, where caterpillar damage was reduced by 38%, sweet pepper
where aphid attacks were reduced by 70%, and caterpillar damage to wheat
was reduced by 65%. |
| BBC News
Oct 07, 2008 |
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| Newly discovered fungus strips pollutants from oil |
A humble fungus could help oil companies clean up their fuel to meet
tightening emissions standards. The fungus, recently discovered in Iran,
grows naturally in crude oil and removes the sulphur and nitrogen
compounds that lead to acid rain and air pollution.
Worldwide, government are imposing increasingly severe limits on how
much of those compounds fuels can contain. Oil producers are searching
for more efficient ways to strip sulphur and nitrogen from their
products. The standard way to 'desulphurise' crude oil involves reacting
it with hydrogen at temperatures of 455°C and up to 204 times
atmospheric pressure. It achieves less than perfect results.
Micro-organisms able to metabolise sulphur and nitrogen have the
potential to achieve the same endpoint under more normal conditions. In
recent years a number of researchers have isolated desulphurising
bacteria. But researchers at the Sharif University of Technology in
Tehran, Iran, have now discovered and isolated a fungus that appears
able to remove sulphur from oil with greater efficiency. The
Stachybotrys fungus removed 76% of sulphur compounds in just 3 days, a
figure only one bacteria could match over the full 6 days. |
| New Scientist / Industrial & Engineering Chemistry Research
Oct 08, 2008 |
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| Gecko-like glue is said to be stickiest yet |
A new type of dry glue designed to mimic gecko feet is 10 times stickier
than the gravity-defying lizards, and three times stickier than other
gecko-inspired glues, according to researchers at the University of
Dayton.
A 2.5-cm square of the adhesive can support the weight of a 100-kg man
climbing up a vertical surface, but it can be easily lifted and
reapplied. Aside from helping people walk up walls, the glue could be
used in electrical components without the need for soldering. And
because it is dry, it could be used at very low temperatures as in
space, where more conventional glues lose their grip.
Like other gecko-inspired glues, the new glue uses a carpet of carbon
nanotubes, thin filaments of carbon molecules. But attached to the ends
of these filaments are curly strands of carbon that expand the surface
area of the glue's gripping action. This design matches the structure of
real gecko feet, which have microscopic hairs that branch off in
different directions. |
| Reuters / Science
Oct 09, 2008 |
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| Giant lens could clean up dusty moon sites |
When it comes to keeping moon dust at bay, nothing beats a little
sunshine. So says a NASA team studying methods to protect a future moon
base from the fine powder on the lunar surface. The dust is easily
disturbed and highly abrasive. It could damage equipment and, if it gets
into inhabited areas, astronauts' lungs.
The answer, says study leader Paul Hintze of the Kennedy Space Center in
Florida, is a 1-metre-wide lens that focuses sunlight to melt and fuse
the dust. In tests on Earth, a solar concentrator heated the soil to
1350 °C, forming a solid crust 6 millimetres deep within 3 minutes.
The team say the technique could be used to create landing and launch
pads for spacecraft as well as roads for lunar vehicles, to cut down the
amount of dust kicked up. |
| New Scientist
Oct 15, 2008 |
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| Monkeys move paralysed muscles with their minds |
A monkey's paralysed wrist can be moved and controlled by electrical
signals artificially routed from its brain, according to scientists who
say that their experiment is a step towards helping paralysed people to
regain the use of their limbs.
Previously, scientists have been able to train monkeys to move robotic
arms using signals routed from electrodes in their brains. This involved
decoding the activity of tens of neurons at a time to replicate actions
such as grasping, and required considerable computing power. Now,
researchers at the University of Washington have used similar signals to
deliver direct electrical stimulation from just one neuron to a
paralysed muscle.
They first implanted a number of electrodes in the motor cortex of two
macaque monkeys. Each electrode picked up signals from a single neuron,
and those signals routed through an external circuit to a computer. The
neuronal signals controlled a cursor on a screen, and the monkeys were
trained to move the cursor using only their brain activity. The
scientists then temporarily paralysed the monkeys' wrist muscles using a
local anaesthetic. They re-routed the signals from the electrodes to
deliver electrical stimulation to the wrist muscles, and found that the
monkeys could control their previously paralysed limbs using the same
brain activity. The monkeys learnt to do this in less than an hour. |
| Nature
Oct 15, 2008 |
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| 'Transparent cockpit' removes car blind spots |
No matter how clean your car's windshield, the view from the driver's
seat is less than perfect. Solid features such as dashboard and doors
can conceal road hazards such as other vehicles and pedestrians.
Now a team of engineers at the University of Tokyo has come up with a
way to make those solid features 'disappear', at least from the driver's
point of view, without modifying them in any way. A pair of stereo
cameras mounted on the passenger-side wing mirror capture scenery hidden
from the driver by the dashboard and the solid parts of doors.
A headset worn by the driver projects the cameras' output onto the solid
features, displaying a clear view of what hides behind them as if they
were transparent. To make the car appear transparent to the driver,
video output from the headset is projected onto a retro-reflective
surface covering the opaque parts of the interior. This surface directs
any light that hits it straight back along its path and produces vivid
video images.
To enhance the illusion of transparency, the projected images must be
scaled correctly. The system does this by using stereo cameras to judge
the distance to objects in view, much the way humans do. The head
position of the driver is also taken into account, using movement
sensors mounted on the headset projector. The result is a true-to-life
view of the outside, as if the opaque parts of the car weren't there. |
| New Scientist
Oct 08, 2008 |
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