Bacteria that function as living electrical cables found

Last Updated: Thursday, October 25, 2012, 21:52
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Washington: Danish scientists have discovered that some bacteria form a kind of gigantic power lines to survive between the different layers of marine mud.

Researchers at Aarhus University, Denmark, made a sensational discovery almost three years ago when they measured electric currents in the seabed.

It was unclear as to what was conducting the current, but the researchers imagined the electric currents might run between different bacteria via a joint external wiring network.

The researchers have now solved the mystery. It turns out that the whole process takes place inside bacteria that are one centimetre long.

They make up a kind of live electric cable that no one had ever imagined existed. Each one of these 'cable bacteria' contains a bundle of insulated wires that conduct an electric current from one end to the other.

"Our experiments showed that the electric connections in the seabed must be solid structures built by bacteria," says PhD student Christian Pfeffer, Aarhus University.

He could interrupt the electric currents by pulling a thin wire horizontally through the seafloor. Just as when an excavator cuts our electric cables.

In microscopes, scientists found a hitherto unknown type of long, multi-cellular bacteria that was always present when scientists measured the electric currents.

"The incredible idea that these bacteria should be electric cables really fell into place when, inside the bacteria, we saw wire-like strings enclosed by a membrane," says Nils Risgaard-Petersen, Aarhus University. Kilometers of living cables

The bacterium is one hundred times thinner than a hair and the whole bacterium functions as an electric cable with a number of insulated wires within it. Quite similar to the electric cables we know from our daily lives.

"Such unique insulated biological wires seem simple but with incredible complexity at nanoscale," says PhD student Jie Song, Aarhus University, who used nanotools to map the electrical properties of the cable bacteria.
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earthquake 'caused by groundwater extraction

Lorca earthquake 'caused by groundwater extraction'

Police officer inspects earthquake damage The relatively modest Magnitude 5.1 quake resulted in extensive damage and nine deaths

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Scientists studying the fault beneath the Spanish city of Lorca say that groundwater removal may be implicated in a deadly 2011 earthquake there.
Detailed surface maps from satellite studies allowed them to infer which parts of the ground moved where.
They report in Nature Geoscience that those shifts correlate with locations where water has been drained for years.
The study highlights how human activity such as drainage or borehole drilling can have far-reaching seismic effects.
Pablo Gonzalez of the University of Western Ontario and colleagues used satellite radar data to trace the ground movements of the Lorca event back to their source, finding that the earthquake resulted from slippage on a comparatively shallow fault that borders a large water basin south of the city.
That the slippage happened at a depth of just 3km explains why the fairly mild Magnitude 5.1 quake caused so much damage in the area.
The team went on to study potential reasons for the slippage, finding that the water table in the adjacent Alto Guadalentin basin had dropped by some 250m over the last 50 years as water was drained for irrigation in the region.
Their calculations show that this created stresses on the fault that initially triggered the earthquake and defined its eventual magnitude.
Geoengineering dreams However, the area lies on a seismically active region, and the data suggest only that the water drainage sped up and eventually triggered a process that would have eventually happened anyway.
The BBC's Sarah Rainsford reported on the damage when the quake struck in 2011
Dr Gonzalez stressed the study was specific to the Lorca earthquake, telling the Reuters news agency that "we cannot set up a rule just by studying a single particular case".
"But the evidence that we have collected in this study could be necessary to expand research in other future events that occur near... dams, aquifers and melting glaciers, where you have tectonic faults close to these sources."
In an accompanying Nature Geoscience article, Jean-Philippe Avouac of the California Institute of Technology said: "It does not take much to trigger an earthquake - even strong rainfall can do the job".

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We should remain cautious of human-induced stress perturbations, in particular those related to carbon dioxide sequestration projects”
Jean-Philippe Avouac California Institute of Technology
"Numerous examples of seismicity triggered by the impoundment of reservoir lakes, hydrocarbon extraction, quarrying and deep well injections have been documented over the years."
Previous research has suggested that the fluid injection associated with the controversial practice of gas extraction by hydraulic fracturing or "fracking" was linked to specific earthquake events.
If science can pin down exactly how stresses from anthropogenic sources distribute and contribute to seismic events, Prof Avouac suggested, "we might dream of one day being able to tame natural faults with geoengineering".
"For now, we should remain cautious of human-induced stress perturbations, in particular those related to carbon dioxide sequestration projects that might affect very large volumes of [the Earth's] crust."

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Science

Airbus designer reveals plans for 3D printed planes by 2050

By Liat Clark
12 July 12
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An Airbus designer is drawing up plans to create a plane from a 3D printer the size of an aircraft hanger by 2050.
Airbus employee Bastian Schafer envisions an 80-metre-long aircraft with a curved body made from transparent material, so passengers feel as though they're flying among the clouds, reports Forbes. Airbus proposed the concept of a 2050 self-cleaning aircraft with inbuilt neural networks, antioxidant enriched air and body heat harvesting facilities in 2011, but how such an aircraft would be built was not explained.
It turns out Schafer has been working on the concept for the past two years, pooling together a team of ten Airbus industrial designers with the ominous promise, "we have an opportunity to do something different".
Despite the cost of building such an obscenely large 3D printer and the feats in technology that need to be mastered before it is even a possibility, the argument is that the resulting lightweight aircraft (65 percent lighter than a normal one, according to parent company the European Aeronautic Defence and Space Company) will be far cheaper to operate. As rocketing fuel prices show no sign of slowing, the idea is appealing.
The innovation arm of Eads opened a £2.6 million Centre for Additive Layer Manufacturing (CALM) back in 2011 with the University of Exeter to explore opportunities for 3D printing in industry, and is already looking to pioneer 3D-printed plane parts. After making a few changes to ensure its model is regulation-ready, Airbus plans to have 3D printed components in the cabins of its A380s by the end of 2012. Its Eurofighter Typhoon military jet already has some internal 3D printed components.
These are mere baby steps towards the production of a plane constructed entirely of 3D printed parts. But it's not just the sheer size that will be an obstacle for Airbus (D-Shape, the biggest 3D printer currently in operation, has only ever made structures of a few metres in height). A type of transparent aluminum sturdy enough to make up the aircraft's body currently only exists in the imagination of the designers and technicians, as do the biopolymers proposed for some of its internal components. Schafer and his team are not too troubled by this, believing that multi-material 3D printers -- such as the one built by Objet -- can be used to generate the new materials. Objet currently offers consumers a range of 107 different materials that can be used with its printer -- this gives engineers the tools to experiment with bonding different materials to create prototypes.
"It's not theoretically impossible," said David Benjamin, a New York architect working with Airbus. "You can design new products that are not all solid and aluminum, but a composite material. You're designing new substances.
"You can dial in the different elasticity of an object, the color properties, or a continuous piece of material that is different properties over the piece. Certain parts of an airplane need to be strong and flexible [and 3D printers can create objects] strong just where they needed to be strong, or light where they needed to be light."
This may be some way off, however, and in the meantime, Schafer is happy to focus on the baby steps. He hopes consumers will be kicking back in 3D printed cabin seats by by 2013.
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