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Issue no. 10, 2012
Published: Mar 30, 2012 |
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 3D design increases solar cell output | | New plastic bleeds and heals like human skin | | Anti-insect wheat trials launched | | Pond skaters' feet inspire buoyant new material | | 'Thermal cloak' hides objects from heat | | 'Nanorefrigerator' is cooled using sunlight | | Capsule could purify radioactive milk, juice | | Modified bacteria could get electricity from sewage | | Cybercrime: EU's 'best brains' to be enlisted to fight | | New search tool to unlock Wikipedia |
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| 3D design increases solar cell output |
MIT researchers are working on 3D solar towers that give a power output
of up to 20 times that of fixed flat panels with the same base area. The
biggest boosts in power were seen just where improvements are most
needed: far from the equator, in winter months and on cloudier days.
The team used a computer algorithm to explore an enormous variety of
possible configurations, and developed analytic software that can test
each one for a range of latitudes, seasons and weather. Then, to confirm
their model's predictions, they built and tested three different
arrangements of solar cells on the roof of an MIT lab for several weeks.
While energy generated by such 3-D modules costs more than that from
ordinary flat panels, this is partially cancelled out by a much higher
output for a given footprint. This matters, because solar cells now cost
less than the associated support structures, wiring and installation,
which account for about 65% of the total.
The system also gives a more uniform power output over the course of a
day, over the seasons of the year and in cloudy conditions. This makes
power output more predictable and uniform, which could make integration
with the power grid easier than with conventional systems.
The main reason for the improvement is that the 3D structures' vertical
surfaces can collect much more sunlight during mornings, evenings and
winters, when the sun is closer to the horizon. Although the models
showed that the biggest advantage would come from complex shapes - such
as a cube where each face is dimpled inward - these would be difficult
to manufacture. However, a simple cube can produce a power output only
about 10 or 15% less than this. The team's also had good results from an
accordion-like tower that can be shipped flat and then unfolded for use. |
| TG Daily / MIT
Mar 27, 2012 |
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| New plastic bleeds and heals like human skin |
A new plastic developed by researchers at the University of Southern
Mississippi not only professes to self-repair when exposed to light, but
to change colour when damaged in a process akin to the bleeding of human
skin.
The new plastic contains molecular bridges that span the polymer chains
that comprise the plastic. Should the plastic become damaged, these
bridges break down; but when exposed to light (or a temperature or
acidic vapour) these linkages are able to repair themselves. But
additionally, the researchers have rigged the bridges to change colour -
to red - when such damage occurs, with the colour change fading away
when the material repairs - essentially heals - itself.
Such a material has obvious benefits when applied to consumer goods,
such as laptops and mobile phones. Dropping the device would result in
hairline cracks turning red, highlighting a need for repair, whereupon
you need only expose it to intense light. But the team also foresee
heavier-duty applications: car fenders, aircraft components and even
battlefield weapons systems among them. |
| GizMag / American Chemical Society
Mar 27, 2012 |
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| Anti-insect wheat trials launched |
The first experiments with plants genetically modified to repel aphids
are under way in the UK. Wheat has been engineered with a gene from a
peppermint plant so that it emits a particular pheromone. The smell is
the alarm signal given off by aphids to warn of an attack by predators.
The researchers hope that this will act as a 'no parking sign' to keep
the pests at bay without needing insecticide.
This is the first trial of a plant deliberately modified to use
pheromones to ward off pests. The work is taking place at Rothamsted
Research, the plant science centre in Hertfordshire. Eight plots of land
- each 36 m2 - have been planted with the GM wheat in the past few days.
One set of wheat in the experiment is fitted with the peppermint gene
only; another set has also been engineered with a synthetic gene. The
goal is to see if the plants give off a highly pure version of the
pheromone, known as A-Farnesene.
Aphids are one of the major threats to the cultivation of wheat.
Experiments have shown that the aphids' sense of smell is highly
sensitive; the insects will not react if they suspect the pheromone has
been released by a plant. A further aim is to see if the pheromone
attracts the aphids' main predator, the tiny parasitic wasp. The
scientists are hoping that GM plants which cut insecticide use will help
gain support for this controversial technology. |
| BBC News
Mar 28, 2012 |
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| Pond skaters' feet inspire buoyant new material |
The feet of pond skaters have helped create a novel super-buoyant
material. Scientists from the Helsinki University of Technology in
Finland have drawn on the structure of the insect's foot to exploit its
ability to let the creature skim across a pond's surface. The buoyancy
of the material has been boosted by making it out of plant cellulose.
The properties that make it float could help it act like a powerful
sponge to aid oil spill clean-ups, say its creators.
The material is a type of aerogel - substances in which the liquid has
been replaced with a gas but the structural components are left in
place. The lightest aerogels are only a few times denser than air itself
and have been called 'solid smoke'.
The aerogel created by the Finnish team uses tiny fibres from plant
cellulose - a natural polymer that, in some ways, resembles plastic.
Cellulose is typically used to make paper and cloth. The researchers
have used a specially processed form of cellulose, known as
nanocellulose, to form their gel.
Early tests based on a cellulose aerogel constructed to a design
suggested by the feet of the pond skater have revealed how buoyant it
is. The team speculate that a 500g chunk of the material could support
five standard household fridges weighing about half a tonne. The work
has also revealed that the material is a very efficient sponge that
could aid oil spill clean-up efforts. |
| BBC News
Mar 26, 2012 |
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| 'Thermal cloak' hides objects from heat |
The range of physical phenomena that scientists are trying to 'cloak'
objects from has a new entry - heat. Researchers at the Institut Fresnel
in France have shown how to apply the ideas of 'optical cloaking' to the
thermal world.
So far, all of the cloaking approaches have limitations that keep them
well short of the invisibility promised in fiction. But more recently,
similar ideas have been put to use to shield objects from magnetic
fields or even from sound or seismic waves.
All of these approaches aim to manipulate the peaks and troughs of waves
to achieve their cloaking effects. However, the transfer of heat is a
subtly different business as heat is not a wave but diffuses from hot to
cold regions. The trick was to apply the mathematics of transformation
optics to the equations describing diffusion; the result, the team
found, was a means to shuttle heat around at will.
The approach is fundamentally different from temperature-changing cloaks
that heat and cool actively to mimic objects of different temperatures
and have proven to 'hide' a tank. In the new technique, the researchers
propose a cloak made of 20 rings of material, each with its own
'diffusivity' - the degree to which it can transmit and dissipate heat.
The cloak could be designed in such a way that heat diffuses around an
invisibility region, which is then protected from heat. Or the heat can
be forced to concentrate in a small volume, which will then heat up very
rapidly. It is this ability to direct and concentrate heat that may find
first application, for instance in the microelectronics industry, where
the heat load in specific areas remains a challenge to engineers. |
| BBC News / Optics Express
Mar 27, 2012 |
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| 'Nanorefrigerator' is cooled using sunlight |
Researchers at Hasselt University, Belgium, have drawn up plans for an
electronic 'nanorefrigerator' device that is driven by high-energy
photons, and so could potentially be directly powered by the Sun. The
researchers propose a rather simple solid-state device that would use
solar energy directly to cool. The device does not first convert solar
energy into electricity, but bypasses the need to generate another form
of energy - which usually results in some amount of energy loss.
The electrode to be cooled is electrically connected to another
electrode that is much warmer. Between the two electrodes are two
quantum dots that act as a highway for electrons to shuffle along from
one electrode to another. The adjoining quantum dots each have a lower
and higher energy level, such that each dot could hold an electron at
any given time in one of the levels.
The researchers suggest using high-temperature photons to make cold
electrons flow from the warm electrode to the cool one, and vice versa
for the warm electrons in the opposite direction. To create this flow, a
cold electron from the warm electrode would hop into the lower energy
level of the first dot, where it must absorb a photon for it to jump to
the lower energy level of the second dot. From there, the cold electron
can make its bid for freedom to the cold electrode, where it would
further decrease the temperature of that electrode. Hot electrons would
make a similar trip in the opposite direction, hopping across the higher
energy level of the dots instead. This net circulation of electrons
would allow one of the electrodes to be efficiently cooled.
The researchers say that one can imagine that the electrons are
'evaporating' out of the cold object and 'condensing' in the warm
object, somewhat like an absorption refrigerator. While the net heat
flow for the device as it is currently described will probably be quite
small, an array of dots could be placed in between the hot and cold
objects to increase the heat exchange. |
| PhysicsWorld / Physical Review Letters
Mar 29, 2012 |
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| Capsule could purify radioactive milk, juice |
Decontaminating milk, baby formula and other drinks following a
radioactive disaster such as Fukushima may soon be simplified using
pellets invented by a US chemist. Allen Apblett from Oklahoma State
University, suggests the ceramic pellets he invented could be used by
food manufacturers to process large batches of liquids such as apple
juice or brown rice syrup contaminated with radioactive or
non-radioactive toxic substances.
Following the 2011 Fukushima disaster in Japan, radiation was detected
in milk, water and some vegetables, prompting restrictions on imports of
Japanese food products. Traces of radioactive caesium were detected in
Japanese infant formula and small amounts of radioactive iodine were
found in milk in the northwest US.
Apblett's pellets are made of a common ceramic called alumina and are
coated with several different kinds of tiny nanoparticles designed to
absorb a variety of radioactive materials such as uranium and strontium,
as well as non-radioactive toxic elements such as lead and arsenic. The
pellets would be placed in a porous capsule and would be too large to
fall out.
Apblett estimates such a capsule could remove all the radioactive
strontium from a container of milk within 12 hours without changing the
taste of the milk. The used pellets don't contain enough radiation to be
harmful and could be recycled. |
| CBC News
Mar 28, 2012 |
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| Modified bacteria could get electricity from sewage |
A fuel cell powered by naturally occurring bacteria has successfully
converted 13% of the energy in sewage to electricity - and cleaned the
waste water at the same time. It's hoped genetic engineering could make
this much more efficient.
Treating sewage and other liquid waste uses roughly 2% of the US energy
supply, at a cost of USD 25bn a year, yet this carbon-rich material
harbours nine times the energy needed to render it environmentally
benign. Microbiologists believe they can drastically cut the cost and
power consumption by using genetically modified bugs to treat the waste
and produce electricity.
The 380-litre microbial fuel cell developed by researchers at the J.
Craig Venter Institute in San Diego, California, uses naturally
occurring microbes to break down organic waste and produce electrons and
protons. The electrons are collected by an anode while the protons pass
through a permeable membrane to a cathode. The resulting voltage between
the two electrodes enables the fuel cell to produce an electric current.
The work represents a significant improvement over the institute's
earlier fuel cell, a 75-litre device able to harvest only 2% of the
waste's potential energy. Further improvements will be needed, however,
for the technology to compete with conventional waste water treatment
techniques, which can rapidly process huge volumes of water.
By genetically modifying microbes to enhance their ability to consume
organic waste, and better shuttling electrons to an electrode, the team
hopes to harvest 30 to 40% of the available energy. |
| New Scientist
Mar 29, 2012 |
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| Cybercrime: EU's 'best brains' to be enlisted to fight |
The European Commission has announced plans to set up a dedicated centre
to fight cybercrime. Based in The Hague, it will be housed alongside
Europol, the pan-European police force. The plan is for the centre to be
up and running by January 2013. It will be primarily focused on fighting
credit card and bank fraud.
'[It] will bring together some of Europe's best brains in the field of
cybercrime,' said Cecilia Malmstrom, European Commissioner for Home
Affairs, at a press conference in Brussels.
More than a third of the EU's 500 million citizens bank online, and an
estimated USD 8tn changes hands globally each year in e-commerce,
according to the Commission. While acknowledging it is hard to put a
figure on the total cost of cybercrime one study estimates it to be USD
388bn a year worldwide.
The centre will provide logistical support for investigations and become
a focal point for European-wide initiatives. Apart from its remit to
fight fraud, the centre will also pay attention to social networks,
online child sexual exploitation and cyber-attacks affecting critical
infrastructures. However, the Commission said its remit would not extend
to pursuing individual file sharers. |
| BBC News
Mar 28, 2012 |
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| New search tool to unlock Wikipedia |
Would you like to ask Wikipedia tougher questions than today's simple
keyword searches allow? A prototype plug-in that can do just that will
be demonstrated at the WWW 2012 conference in Lyon, France, next month.
Called Swipe - short for 'searching Wikipedia by example' - the software
aims to let users of the encyclopaedia answer complex questions that most
search engines would stumble over. For example, trying to figure out
'which actresses won academy awards when they were under 30 years old in
the last 25 years?' becomes relatively simple when using the program.
To use Swipe, questions are not typed out in the form of the natural
language above, but Swipe is nevertheless designed for everyday users:
no knowledge of arcane database query languages is necessary, say the
developers. They wrote Swipe using MediaWiki, the software Wikipedia is
based on, but it draws its answers from DBpedia, an expansive collection
of 3.6m data entries harvested from Wikipedia's pages. The data pop up
in the info boxes on the right-hand side of Wikipedia entries, which
list the details we use to describe the world, such as dates, prices,
ages, heights, names, places, distances, bit rates, bytes, running times
and geographical coordinates.
At a very basic level, the researchers use this process in reverse:
Swipe 'activates' those Wikipedia info boxes, allowing users to take the
data in them and create a tweaked version, and in doing so calls up
pages that match that altered information. Swipe could easily be made
available as an option on Wikipedia one day, the researchers say. |
| New Scientist
Mar 28, 2012 |
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