- Printable, Moldable Batteries Made From Paper and Nanotubes
- 3 Scientific Bets the DOE Is Placing to Break the Climate Stalemate
- Rudiments of Language Discovered in Monkeys
Posted: 08 Dec 2009 03:00 AM PST
Those who are quick to dismiss paper as old-fashioned should hold off on the trash talk. Scientists have made batteries and supercapacitors with little more than ordinary office paper and some carbon and silver nanomaterials. The research, published online December 7 in Proceedings of the National Academy of Sciences, brings scientists closer to lightweight printable batteries that may one day be molded into computers, cell phones or solar panels.
"Power storage is one of the very important aspects of solving the energy issue," comments Robert Linhardt of Rensselaer Polytechnic Institute in Troy, N.Y. The paper-based devices show excellent performance.
That performance is largely due to paper's porous nature: at the nano scale, paper is a tangled matrix of fibers. This vast surface area helps inks stick, says Yi Cui of Stanford University, coauthor of the new work. This holds true for carbon nanotube ink as well. When carbon-nanotube ink touches paper, the nanotubes "get caught very tightly to the cellulose," says Cui, probably just via good old electrostatic forces.
The paper acts as a scaffold, and the carbon nanotubes act as electrodes that electrolytes in solution react with. This nanotube-paper combination offers a lightweight alternative to traditional energy storage devices that rely on metals.
By sandwiching a piece of untreated paper between two pieces inked with carbon nanotubes and then placing the layers in an electrolyte solution, the researchers made conductive paper that could be bent and rolled. When adhesive tape was applied to the paper and then pulled off, the ink didn't peel off with the tape, a problem with other energy storage materials made with plastic films, the researchers note. Silver nanowires also made the paper conductive.
Calculations suggest that conductive paper coated with a kilogram of the carbon nanotubes could power a 40-watt bulb for an hour, making the paper more efficient than plastic-based versions of flat energy-storage devices. The scientists also used the conductive paper to collect current inside lithium-ion batteries and were able to power a light-emitting diode, or LED.
While previous work has used cellulose as a backbone for conductive materials, this demonstration is the first with ordinary office paper, says Cui. The next step is to take the technology to a larger scale, which might not be a huge hurdle, he says, since paper making and printing are well-developed technologies.
Images: 1) Scanning electron microscope images of paper (left) and paper coated with carbon nanotubes (right)/Yi Cui. 2) Demonstrating the flexibility of the carbon-nanotube ink coated paper/Yi Cui.
Posted: 07 Dec 2009 12:54 PM PST
The Advanced Research Projects Agency for energy put out its second call for new ideas, and this time, the agency has narrowed its focused to three research fields.
The new arm of the Department of Energy, which is dedicated to high-risk, high-reward innovations, is betting $100 million on batteries for cars, new materials for capturing carbon, and microorganisms that can convert sunlight and carbon dioxide directly into fuels.
"This solicitation focuses on three cutting-edge technology areas which could have a transformational impact," said Energy Secretary Steven Chu, in a release.
Energy gets used in a lot of different ways, so no single technology can make all the difference. That said, a few key pieces of technology would provide the political world with better clean energy options. We use coal to make half the nation's electricity. Fossil fuels, mostly oil, burned for transportation account for roughly one-third of American emissions. Finding cheaper, cleaner solutions to the key problems of baseload generation and fuel for cars would be major steps towards reducing carbon emission and dependence on foreign oil.
This is the second call for proposals the DOE outfit, modeled after the military's Defense Advanced Research Projects Agency, has issued. This new request is as narrow as the last was wide. In the first grants announced in October, ARPA-E spread the first $150 million from its coffers broadly on 37 different technologies across the energy landscape from building efficiency to biomass conversion to waste heat capture. Each endeavor received between half a million and nine million dollars.
Energy-dense, low-cost, long-lived batteries have been a dream of inventors since Thomas Edison claimed to have solved the problem in 1901. His battery was described by The New York Times as "combining all of the long-sought advantages of lightness, durability, and effectiveness." It was so good, in fact, that "it was predicted that a new art of electrical propulsion and navigation would result."
Though that has yet to happen, scientific knowledge of materials at the nanoscale has grown by leaps and bounds. ARPA-E is looking for battery-makers who can meet the ambitious goals (pdf) laid out by the United States Advanced Battery Consortium, a group of carmakers working with the government.
Another area where scientific knowledge has been growing at an astounding pace is microbiological genomics. Scientists have gone beyond understanding individual gene functions to tweaking them for specialized functions. Synthetic biologists are working to develop microorganisms that are, in essence, programmable. One company, LS9, calls them DesignerMicrobesTM. The equation that the DOE would like these biological machines to solve is simple: CO2 and sunlight in, a substitute for oil out. Already, a flock of synthetic biology companies like Amyris, Solazyme, and Synthetic Genomics are trying to create alternatives to oil using microorganismal genomics, and the DOE would like to see more.
Carbon dioxide capture is considered a mainline strategy for reducing carbon dioxide emissions by the Intergovernmental Panel on Climate Change, but it requires a substantial percentage of the energy that the plant produces to do it. It's thought that new materials could, as the DOE puts it, "dramatically reduce the parasitic energy penalties and corresponding increase in the cost of electricity required for carbon capture."
Some labs, like Omar Yaghi's at UCLA and Gerbrand Ceder's at MIT, have developed new methods for finding large amounts of new materials and determining their properties. Their work is a promising start, but more carbon capture isn't the only step needed to keep smokestack emissions from warming the earth. They also have to be permanently buried. Last year, energy researcher Vaclav Smil at the University of Manitoba estimated that to bury just 25 percent of CO2 produced by power plants would required moving twice the material the world's crude-oil industry (pdf) does now. That's a tall order and would require a heck of a lot of pipes and caverns.
Image: A prototype sunlight-to-fuel solar furnace at Sandia National Laboratory.
Posted: 07 Dec 2009 12:06 PM PST
Campbell's monkeys appear to combine the same calls in different ways, using rules of grammar that turn sound into language.
Whether their rudimentary syntax echoes the speech of humanity's evolutionary ancestors, or represents an emergence of language unrelated to our own, is unclear. Either way, they're far more sophisticated than we thought.
"This is the first evidence we have in animal communication that they can combine, in a semantic way, different calls to create a new message," said Alban Lemasson, a primatologist at the University of Rennes in France. "I'm not sure it has strong parallels with humans, in the way that we will find a subject and object and verb. But they have meaningful units combined into other meaningful sequences, with rules imposed on how they're combined."
Lemasson's team previously described the monkeys' use of calls with specific meanings in a paper published in November. It detailed the monkeys' basic sound structures and their uses: "Hok" for eagle, "krak" for leopard, "krak-oo" for general disturbance, "hok-oo" and "wak-oo" for general disturbance in forest canopies. A sixth call, "boom," was used in non-predatory contexts, such as when calling a group together for travel or arguing with neighboring groups.
Impressive as that was, however, it was still relatively one-dimensional, not much different from verbalizations heard in many animal species, from other non-human primates to songbirds. The team's latest findings, published Monday in the Proceedings of the National Academy of Sciences, describe something far more complicated: syntax, or principles of word sequence and sentence structure.
Though some researchers have ascribed syntax to animals, it's never been formally demonstrated — until now.
"People have criticized the use of 'syntax' to describe animals just because they produce sequences of sound. They say that each unit has no meaning, that no rules explain how they're combined," said Lemasson. "Here we have rules of combination."
For example, male monkeys called "boom boom" to gather other monkeys to them, but "boom boom krak-oo krak-oo" meant that a tree or branch was about to fall. Adding a "hak-oo" to that sequence turned it into a territorial warning against stray monkeys from neigboring groups. Multiple "krak-oo" calls added to an original "krak" meant not only that a leopard was in the area, but that it posed an immediate threat.
The research raises the question of whether early humans or our primate ancestors combined calls in a similar way, turning a small set of sounds into a rich verbal reportoire.
According to Lemasson and to Jared Taglialatela, a chimpanzee communication researcher at Clayton State University, it's too soon to say whether the monkey talk is proto-human.
"I'd shy away from that. But this is certainly syntax," said Taglialatela, who was not involved in the study. But he described the proto-human question as secondary to a far more intriguing possibility: that the potential for language is widespread in the animal kingdom.
"People like to draw lines and make boxes and put animals inside them. I don't like to do that. There are differences and shades of grey. And when you take the time to collect data in a way that allows you to recognize complexity and patterns, than you find evidence of them," said Taglialatela.
Lemasson's analysis was based on a vast set of recordings, gathered from 10 monkey groups observed for two full years in their African rain forest homes.
Lemasson, who is further investigating Campbell's monkey talk by measuring their reactions to recorded calls, suspects that a dense jungle environment drove the evolution of syntax. Since the monkeys had trouble seeing each other, they compensated by talking.
The same compensatory dynamic could operate in other species, such as whales that live in mostly sunless waters, he said.
"We can imagine that this ability has evolved in other lineages," said Lemasson.
Image: Florian Möllers
Citation: "Generating meaning with finite means in Campbell's monkeys." By Karim Ouattara, Alban Lemasson, and Klaus Zuberbuhler. Proceedings of the National Academy of Sciences, Vol. 106 No. 48, December 7, 2009.
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