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Image: eutrophication&hypoxia
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Issue no. 6, 2012
Published: Mar 02, 2012 |
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 Giving waste water the power to clean itself | | Graphyne could be better than graphene | | Neutrino speed errors dash exotic physics dreams | | CERN to tap new Europe cloud computing project | | Giant desert greenhouse inspired by camel's nostrils | | Astronomers detect signs of life on Earth | | Neanderthals were ancient mariners |
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| Giving waste water the power to clean itself |
A technique that combines two novel forms of renewable energy generates
more electricity than either one alone and cleans waste water at the
same time.
Waste water contains a great deal of energy in the form of organic
matter, according to researchers at the Hydrogen Energy Center and the
Engineering Energy and Environment Institute at Pennsylvania State
University. Domestic waste water contains nine times more chemical
energy than the energy required to treat it — that amount, added to the
energy in waste water from livestock and food production, would be
nearly enough energy to maintain the entire US water infrastructure.
One method for converting this energy to a useable form is to use
microbial fuel cells (MFC). These generate electricity by using cultures
of microorganisms to break down and oxidise organic matter, a process
that releases electrons that migrate towards a positive electrode. At
the same time, hydrogen ions from the water pass through a proton-
exchange membrane and into a separate cathode chamber. The electrons are
drawn to the cathode from the anode via a circuit, generating an
electrical current, where they combine with the hydrogen ions and
ambient oxygen to form clean water.
MFC technology is almost ready for commercialization, but the power
densities — the amount of power each system generates per square metre
of cathode surface area — could be higher. To boost the power density of
the MFC system, the team added to it a second process, called reverse
electrodialysis (RED), in which the salinity gradient between fresh
water and sea water is harnessed to generate electricity.
The researchers’ system, called a microbial reverse-electrodialysis cell
(MRC), would be capable of producing 0.94 kilowatt-hours of electrical
energy per kilogram of organic waste, according to the researchers.
Conventional treatment of waste water, by constrast, typically consumes
around 1.2 kilowatt-hours per kilogram. |
| Nature / Science
Mar 01, 2012 |
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| Graphyne could be better than graphene |
Graphene, a layer of graphite just one atom thick, isn't called a wonder
material for nothing. The material is famed for its superlative
mechanical and electronic properties. Yet new computer simulations
suggest that the electronic properties of a little-known sister material
of graphene called graphyne may in some ways be better.
The simulations show that graphyne's conduction electrons should travel
extremely fast—as they do in graphene, but in only one direction. That
property could help researchers design faster transistors and other
electronic components that process one-way current, according to
researchers at the University of Erlangen-Nuremberg in Germany.
Electrically, graphene's structure has been considered unique. In most
materials, conduction electrons have an energy that depends on the
square of their momentum. Graphene's electronic energy levels, however,
stack into shapes called Dirac cones, which allow conduction electrons
to travel with an energy that is directly proportional to their
momentum. As a result, the electrons travel as though they were
massless, the way particles of light do - in other words, very fast.
Graphyne is similar to graphene in that it is also a two-dimensional
structure of carbon. Unlike graphene, though, graphyne contains double
and triple bonds and its atoms do not always have a hexagonal
arrangement. Indeed, there may be a vast number of possible graphynes,
each with the double and triple bonds in slightly different
arrangements. Theorists have been studying graphynes since the 1980s,
but little work has been devoted to their electronic properties.
The team have now examined these electronic properties in computer
simulations, using a technique called density functional theory. This is
standard for mapping the energy levels of different possible forms of
the material. The researchers discovered that in one particular graphyne
— so-called 6,6,12-graphyne - Dirac cones should still exist but in a
distorted, squashed form. As a result the material should conduct
electrons in a preferred direction, according to the team. |
| Science Magazine / Physical Review Letters
Mar 01, 2012 |
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| Neutrino speed errors dash exotic physics dreams |
Extra dimensions. Time travel. Tachyons. These ideas seemed a little
more likely in the wake of claims that subatomic particles called
neutrinos had moved faster than light - violating a cornerstone of
physics laid down by Einstein. Now, just a few months later, the
universe is back to its slightly more mundane self.
The collaboration behind the original claims has discovered two flaws
during the retesting of its experiment, called OPERA. These flaws did
not definitely affect the results, but offer the most concrete basis yet
for doubting that the neutrinos were actually speeding. The first error
was caused by a faulty fibre-optic cable. The second error came from a
faulty clock.
The OPERA collaboration shocked the world last September when it
reported that neutrinos from a particle accelerator at CERN near Geneva
had arrived at a detector in the Gran Sasso mountain, Italy, 60
nanoseconds earlier than if they had been travelling at the speed of
light. The result contradicted Einstein's special theory of relativity,
which says that nothing can accelerate beyond the speed of light.
OPERA plans to start rerunning the experiment in May with a replaced
clock and repaired cable. An experiment at Fermilab in Batavia,
Illinois, meanwhile is set to re-test the result. |
| New Scientist
Feb 29, 2012 |
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| CERN to tap new Europe cloud computing project |
Three research centres and a consortium of internet companies have
announced they will work together on a European cloud computing platform
to handle Europe's rapidly growing demand for computer capacity. CERN,
the Geneva-based particle physics organisation, said the platform -
dubbed 'Helix Nebula-the Science Cloud' - would be made available to
government bodies and industry after a two-year pilot phase.
Also participating in the programme are the European Space Agency (ESA)
and the German-based European Molecular Biology Laboratory (EMBL), which
like CERN are gathering vast volumes of information that cannot
presently be processed. The 13 information technology providers involved
include Atos, Cap Gemini, Logica, Orange, Telefonica and Thales.
Cloud computing centralises data and applications in remote - usually
commercial - computer banks rather than onsite in institutions,
companies and homes, and allows the sharing of processing and data
storage. It also turns computing power from a commodity, that may or may
not be used to the full by a single user, into a service users can draw
- and pay for - only what they need over the internet. |
| Reuters
Mar 01, 2012 |
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| Giant desert greenhouse inspired by camel's nostrils |
A unique greenhouse that is irrigated using seawater will be built in
the desert by the end of this year. The USD 5.3m Sahara Forest Project,
just outside Doha in the Qatari desert, will borrow tricks from nature
to extract the salt and create conditions that are ripe for plant
growth, all without any external energy or resources.
The 10,000m2 site works by exploiting the difference in temperature
between surface seawater and water taken from deep below the surface.
Using solar power, these are both pumped to the site through separate
pipes. The hot desert air is used to evaporate the warm surface water as
it flows over 'evaporative hedges' at one side of the greenhouse. This
now cooled, moist air passes over the plants creating a comfortable
temperature around them, and then condenses as it passes pipes through
which the cold deep seawater is pumped, creating fresh water.
It is an idea that is inspired by the way a camel's nostrils evaporates
and condenses moisture to keep it cool, and by the way fog-basking
beetles are able to capture water from the warm night air in the desert.
The saltwater will also be used to grow algae which will be used in
biomass production.
The pilot plant should be functioning by July, in time to receive
visitors during the COP 18 Climate Change talks in November. If it is
successful, it could pave the way for much larger industrial scale
greenhouses in the Middle-East. |
| New Scientist
Feb 29, 2012 |
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| Astronomers detect signs of life on Earth |
Scientists have developed a new method to study reflected light from the
Earth, that can correctly measure the amount of cloud cover, ocean and
vegetation our planet has. The research will allow astronomers to
eventually study the atmospheric and surface features of planets in
other solar systems.
Scientists from the European Southern Observatory in Chile, used
spectroscopy and light polarisation to look for chemical bio-signatures
in Earthshine - sunlight reflected by the Earth onto the surface of the
Moon and back again. Light passing through the Earth's atmosphere
contains a tell-tale spectrum revealing the elements within the gas. It
is also strongly polarised by scattering from air molecules, aerosols
and cloud particles, and by reflection off the oceans and land.
By combining these characteristics in a technique called
spectropolarimetry, The team successfully obtained information about the
Earth from reflected light that wouldn't be achieved by normal
spectroscopic readings alone. They report finding molecular oxygen,
methane, as well as ozone and water vapour, which were used to
characterize the properties of clouds and aerosols.
The readings allowed them to determine the contribution of cloud, ocean
surface and vegetation to the signatures. The measurements are sensitive
enough to detect visible areas of vegetation as low as 10%. |
| ABC News / Nature
Mar 01, 2012 |
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| Neanderthals were ancient mariners |
It looks like Neanderthals may have beaten modern humans to the seas.
Growing evidence suggests our extinct cousins criss-crossed the
Mediterranean in boats from 100,000 years ago. Neanderthals lived around
the Mediterranean from 300,000 years ago. Their distinctive 'Mousterian'
stone tools are found on the Greek mainland and, intriguingly, have also
been found on the Greek islands of Lefkada, Kefalonia and Zakynthos.
That could be explained in two ways: either the islands weren't islands
at the time, or our distant cousins crossed the water somehow.
Now, George Ferentinos of the University of Patras in Greece says we can
rule out the former. The islands, have been cut off from the mainland
for as long as the tools have been on them. Ferentinos compiled data
that showed sea levels were 120m lower 100,000 years ago, because water
was locked up in Earth's larger ice caps. But the seabed off Greece
today drops down to around 300m, meaning that when Neanderthals were in
the region, the sea would have been at least 180m deep.
Ferentinos thinks Neanderthals had a seafaring culture for tens of
thousands of years. Modern humans are thought to have taken to the seas
just 50,000 years ago, on crossing to Australia.
The journeys to the Greek islands from the mainland were quite short - 5
to 12km - but according to Thomas Strasser of Providence College in
Rhode Island, the Neanderthals didn't stop there. In 2008 he found
similar stone tools on Crete, which he says are at least 130,000 years
old. Crete has been an island for some 5m years and is 40km from its
closest neighbour - suggesting far more ambitious journeys.
Even if Ferentinos is right, the Neanderthals were probably not the
first hominin seafarers. One million-year-old stone tools have been
found on the Indonesian island of Flores. Some hominids, perhaps Homo
erectus, crossed the sea to Flores before Neanderthals even evolved. |
| New Scientist / Journal of Archaeological Science
Feb 29, 2012 |
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