Wednesday, November 30, 2011

Correction: Climate Conference-Q&A (AP)

JOHANNESBURG ? In a Nov. 28 Q&A on the U.N. climate conference in Durban, The Associated Press reported erroneously that the United States has never signed the Kyoto Protocol. U.S. negotiators signed the agreement, but it was not submitted to Congress for ratification and Washington later formally withdrew from it.

Source: http://us.rd.yahoo.com/dailynews/rss/environment/*http%3A//news.yahoo.com/s/ap/20111129/ap_on_re_af/af_climate_conference_q_a_corrective

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Graphene foam detects explosives, emissions better than today's gas sensors

ScienceDaily (Nov. 28, 2011) ? A new study from Rensselaer Polytechnic Institute demonstrates how graphene foam can outperform leading commercial gas sensors in detecting potentially dangerous and explosive chemicals. The discovery opens the door for a new generation of gas sensors to be used by bomb squads, law enforcement officials, defense organizations, and in various industrial settings.

The new sensor successfully and repeatedly measured ammonia (NH3) and nitrogen dioxide (NO2) at concentrations as small as 20 parts-per-million. Made from continuous graphene nanosheets that grow into a foam-like structure about the size of a postage stamp and thickness of felt, the sensor is flexible, rugged, and finally overcomes the shortcomings that have prevented nanostructure-based gas detectors from reaching the marketplace.

Results of the study were published November 28 in the journal Scientific Reports, published by Nature Publishing Group.

"We are very excited about this new discovery, which we think could lead to new commercial gas sensors," said Rensselaer Engineering Professor Nikhil Koratkar, who co-led the study along with Professor Hui-Ming Cheng at the Shenyang National Laboratory for Materials Science at the Chinese Academy of Sciences. "So far, the sensors have shown to be significantly more sensitive at detecting ammonia and nitrogen dioxide at room temperature than the commercial gas detectors on the market today."

Over the past decade researchers have shown that individual nanostructures are extremely sensitive to chemicals and different gases. To build and operate a device using an individual nanostructure for gas detection, however, has proven to be far too complex, expensive, and unreliable to be commercially viable, Koratkar said. Such an endeavor would involve creating and manipulating the position of the individual nanostructure, locating it using microscopy, using lithography to apply gold contacts, followed by other slow, costly steps. Embedded within a handheld device, such a single nanostructure can be easily damaged and rendered inoperable. Additionally, it can be challenging to "clean" the detected gas from the single nanostructure.

The new postage stamp-sized structure developed by Koratkar has all of the same attractive properties as an individual nanostructure, but is much easier to work with because of its large, macroscale size. Koratkar's collaborators at the Chinese Academy of Sciences grew graphene on a structure of nickel foam. After removing the nickel foam, what's left is a large, free-standing network of foam-like graphene. Essentially a single layer of the graphite found commonly in our pencils or the charcoal we burn on our barbeques, graphene is an atom-thick sheet of carbon atoms arranged like a nanoscale chicken-wire fence. The walls of the foam-like graphene sensor are composed of continuous graphene sheets without any physical breaks or interfaces between the sheets.

Koartkar and his students developed the idea to use this graphene foam structure as a gas detector. As a result of exposing the graphene foam to air contaminated with trace amounts of ammonia or nitrogen dioxide, the researchers found that the gas particles stuck, or adsorbed, to the foam's surface. This change in surface chemistry has a distinct impact upon the electrical resistance of the graphene. Measuring this change in resistance is the mechanism by which the sensor can detect different gases.

Additionally, the graphene foam gas detector is very convenient to clean. By applying a ~100 milliampere current through the graphene structure, Koratkar's team was able to heat the graphene foam enough to unattach, or desorb, all of the adsorbed gas particles. This cleaning mechanism has no impact on the graphene foam's ability to detect gases, which means the detection process is fully reversible and a device based on this new technology would be low power -- no need for external heaters to clean the foam -- and reusable.

Koratkar chose ammonia as a test gas to demonstrate the proof-of-concept for this new detector. Ammonium nitrate is present in many explosives and is known to gradually decompose and release trace amounts of ammonia. As a result, ammonia detectors are often used to test for the presence of an explosive. A toxic gas, ammonia also is used in a variety of industrial and medical processes, for which detectors are necessary to monitor for leaks.

Results of the study show the new graphene foam structure detected ammonia at 1,000 parts-per-million in 5 to 10 minutes at room temperature and atmospheric pressure. The accompanying change in the graphene's electrical resistance was about 30 percent. This compared favorably to commercially available conducting polymer sensors, which undergo a 30 percent resistance change in 5 to 10 minutes when exposed to 10,000 parts-per-million of ammonia. In the same time frame and with the same change in resistance, the graphene foam detector was 10 times as sensitive. The graphene foam detector's sensitivity is effective down to 20 parts-per-million, much lower than the commercially available devices. Additionally, many of the commercially available devices require high power consumption since they provide adequate sensitivity only at high temperatures, whereas the graphene foam detector operates at room temperature.

Koratkar's team used nitrogen dioxide as the second test gas. Different explosives including nitrocellulose gradually degrade, and are known to produce nitrogen dioxide gas as a byproduct. As a result, nitrogen dioxide also is used as a marker when testing for explosives. Additionally, nitrogen dioxide is a common pollutant found in combustion and auto emissions. Many different environmental monitoring systems feature real-time nitrogen dioxide detection.

The new graphene foam sensor detected nitrogen dioxide at 100 parts-per-million by a 10 percent resistance change in 5 to 10 minutes at room temperature and atmospheric pressure. It showed to be 10 times more sensitive than commercial conducting polymer sensors, which typically detect nitrogen dioxide at 1,000 part-per-million in the same time and with the same resistance chance at room temperature. Other nitrogen dioxide detectors available today require high power consumption and high temperatures to provide adequate sensitivity. The graphene foam sensor can detect nitrogen dioxide down to 20 parts-per-million at room temperature.

"We see this as the first practical nanostructure-based gas detector that's viable for commercialization," said Koratkar, a professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer. "Our results show the graphene foam is able to detect ammonia and nitrogen dioxide at a concentration that is an order of magnitude lower than commercial gas detectors on the market today."

The graphene foam can be engineered to detect many different gases beyond ammonia and nitrogen dioxide, he said.

Studies have shown the electrical conductivity of an individual nanotube, nanowire, or graphene sheet is acutely sensitive to gas adsorbtion. But the small size of individual nanostructures made it costly and challenging to develop into a device, plus the structures are delicate and often don't yield consistent results.

The new graphene foam gas sensor overcomes these challenges. It is easy to handle and manipulate because of its large, macroscale size. The sensor also is flexible, rugged, and robust enough to handle wear and tear inside of a device. Plus it is fully reversible, and the results it provides are consistent and repeatable. Most important, the graphene foam is highly sensitive, thanks to its 3-D, porous structure that allows gases to easily adsorb to its huge surface area. Despite its large size, the graphene foam structure essentially functions as a single nanostructure. There are no breaks in the graphene network, which means there are no interfaces to overcome, and electrons flow freely with little resistance. This adds to the foam's sensitivity to gases.

"In a sense we have overcome the Achilles' heel of nanotechnology for chemical sensing," Koratkar said. "A single nanostructure works great, but doesn't mean much when applied in a real device in the real world. When you try to scale it up to macroscale proportions, the interfaces defeats what you're trying to accomplish, as the nanostructure's properties are dominated by interfaces. Now we're able to scale up graphene in a way that the interfaces are not present. This allows us to take advantage of the intrinsic properties of the nanostructure, yet work with a macroscopic structure that gives us repeatability, reliability, and robustness, but shows similar sensitivity to gas adsorbtion as a single nanostructure."

Along with Koratkar, co-authors of the paper are: Rensselaer graduate students Fazel Yavari and Abhay Varghese Thomas; along with professors W.C. Ren, H.M. Cheng and graduate student Z.P. Chen of the Shenyang National Laboratory for Materials Science at the Chinese Academy of Sciences.

This research was supported in part by the Advanced Energy Consortium (AEC), the National Science Foundation of China, and the Chinese Academy of Sciences.

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The above story is reprinted from materials provided by Rensselaer Polytechnic Institute.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Fazel Yavari, Zongping Chen, Abhay V. Thomas, Wencai Ren, Hui-Ming Cheng, Nikhil Koratkar. High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network. Scientific Reports, 2011; 1 DOI: 10.1038/srep00166

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Source: http://www.sciencedaily.com/releases/2011/11/111128132730.htm

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Monday, November 28, 2011

World stocks up after robust US holiday shopping (AP)

BANGKOK ? World stocks were boosted Monday by a robust start to the U.S. holiday shopping season and reports that European leaders are considering legal means to force debt-ridden euro countries into fiscal discipline.

Benchmark oil rose above $99 per barrel and the dollar fell against the euro and the yen.

European stock markets rose in early trading. Britain's FTSE 100 added 1.4 percent to 5,235.40. Germany's DAX gained 2 percent to 5,601.80 and France's CAC-40 jumped 2.1 percent to 2,917.54.

Wall Street also appeared headed for a higher opening, with Dow Jones industrial futures rising 1.6 percent to 11,370 and S&P 500 futures jumping 2 percent at 1,176.70.

The gains in Europe tracked those in Asia earlier in the day. Japan's Nikkei 225 index jumped 1.6 percent to close at 8,287.49. South Korea's Kospi gained 2.2 percent to 1,815.28 and Hong Kong's Hang Seng rose 2 percent to 18,037.81. Australia's S&P/ASX 200 added 1.9 percent to 4,058.20.

Benchmarks in Singapore, Taiwan and Thailand were also higher. Those in Indonesia and the Philippines fell. In mainland China, the benchmark Shanghai Composite Index gained 0.1 percent to 2,383.03.

German media reported over the weekend that German Chancellor Angela Merkel and French President Nicolas Sarkozy were studying legal changes ? possibly amendments to the European Union growth and stability pact ? to force nations using the euro common currency to comply with strict rules for budget discipline and tough sanctions for violators.

The reports raised hopes that the region may be able to stem a debt crisis that has infected peripheral countries like Greece and is threatening bigger countries like Spain.

Surprisingly strong Thanksgiving sales in the U.S. also helped boost market sentiment, said Francis Lun, managing director of Lyncean Holdings in Hong Kong.

A record 226 million shoppers visited stores and websites during the four-day U.S. holiday weekend starting on Thanksgiving Day, according to early estimates by The National Retail Federation. The results for the first holiday shopping weekend show that retailers' efforts to lure shoppers during the weak economy are working. Holiday shopping can account for 25 to 40 percent of a merchant's annual revenue.

But what really got markets going, Lun said, were Italian media reports that the International Monetary Fund was preparing up to 600 billion euros in loans for cash-strapped Italy, whose massive debts are becoming unmanageable because of soaring borrowing costs.

"It's a relief that we won't see the demise of the euro just yet. The end of the world is delayed for another week," he said. "The problem facing Europe now is that a lot of these smaller countries do not play by the rules. So now one by one, they are falling like dominoes, becoming satellites of Germany, at least in the economic sense."

But some analysts paid little heed to the report, saying the IMF simply could not afford such a loan.

"As of September the IMF had $385.5 billion of forward commitment capacity, so even if they designated their whole fund to Italy it would be well below the amount that has been speculated," Stan Shamu of IG Markets in Melbourne said in a report. "It would require huge increases in contributions from other nations."

Worries about Europe's debt crisis flared anew Friday after Italy had to pay 7.8 percent to borrow for two years at a debt auction. It's another sign that investors are increasingly hesitant to lend to European countries. Greece, Ireland and Portugal had to seek bailouts from international lenders when their interest rates crossed the 7 percent mark.

Gains in Asia were broad-based. South Korea's LG Electronics soared 8.6 percent, while Hynix Semiconductor added 7.1 percent. Hong Kong-listed Anhui Conch Cement gained 5.1 percent and China Railway Group was up 6.3 percent.

Japan's top three carmakers ? Toyota, Honda and Nissan Motor Corps. ? all posted gains of at least 2.9 percent.

But Olympus Corp., which is fighting to restore its reputation from a scandal involving the cover-up of huge investment losses, slid 10.6 percent. Australia's Woodside Petroleum fell 2.3 percent after downgrading its 2012 oil and gas production targets.

Shanghai-listed Chongqing Three Gorges Water Conservancy gained 6.8 percent while Sichuan Mingxing Electric Power Co. Ltd. rose 4.2 percent after a rumor said the authorities may raise electricity fees to combat higher coal costs.

During a shortened post-holiday trading session on Friday, the Dow fell 0.2 percent to close at 11,231.78. The S&P 500 lost 0.3 percent to 1,158.67. The Nasdaq composite dropped 0.8 percent to close at 2,441.51.

Benchmark crude for January delivery was up $2.32 to $99.12 per barrel in electronic trading on the New York Mercantile Exchange. The contract rose $1.09 to finish at $98.01 per barrel on the Nymex on Friday.

In currency trading, the euro rose to $1.3332 from $1.3230 late Friday in New York. The dollar weakened to 77.66 yen from 77.76 yen.

Source: http://us.rd.yahoo.com/dailynews/rss/stocks/*http%3A//news.yahoo.com/s/ap/20111128/ap_on_bi_ge/world_markets

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Lucasfilm's Indiana Jones Ventures Into Social Gaming With Zynga's ...

?NEW YORK - Lucasfilm's Indiana Jones is coming to social gaming giant Zynga's Adventure World in a big way on Tuesday in what is Indy's first venture into the social game space. ??

As part of a collaboration between the companies that has been in the works for a while, the Facebook game will be renamed Indiana Jones Adventure World, and the whip-carrying hero will be weaved into the game's story, according to Zynga. ??

Plus, the company will on Tuesday launch a new chapter of the game called Indiana Jones: And the Calendar of the Sun, in which players team up with Indy in search of a lost treasure. While they do not control the hero played on the big screen by Harrison Ford, he shows up regularly, gives players advice and helps them collect points.

??Zynga, which has a filed for an IPO that is expected by year's end, has previously worked with film studios, such as Paramount and DreamWorks Animation, and music stars, such as Lady Gaga and Enrique Iglesias, to offer short-term integrations that promoted new film or album releases and the like. But the Indy partnership is Zynga?s first long-term arrangement with an entertainment partner.

Zynga had in September said that Indy would come to Adventure World, but hadn't shared detailed plans.

??"Our Adventure World players have seen Indy in messages before, but this is the first time they can interact with him," Toby Ragaini, executive producer of the game, told The Hollywood Reporter. "And we worked hard with Lucasfilm to get the character right. For example, he is afraid of snakes - just like in the films."

??The companies didn't disclose financial details of the licensing agreement and partnership. Adventure World has 1.5 million daily and 9.2 million monthly active players, according to AppData. Zynga executives wouldn't say how many incremental players the addition of Indiana Jones could draw to the game.

??"It felt like a good marriage," Nabeel Hyatt, general manager, Zynga Boston, told The Hollywood Reporter. "This is not a short-term, but long-term relationship, which is new for Zynga. We talked very early on, but it took this long to get it right in partnership with Lucasfilm."???

Indiana Jones: And the Calendar of the Sun sees Indy join players on their adventure as they trek across the jungle to find the Calendar of the Sun, while a competing group has a head start. ??

?The story takes place prior to the Indiana Jones films, around 1934, and includes Forrestal, a rival adventurer mentioned in Raiders of the Lost Ark, as well as some items from the films.??

In future releases of the game, players will also get access to some of Indiana Jones gear and gadgets, including snake bait, a bear trap and outfits.??

Why do players not get to play Indy himself? "We take additions to a game very seriously," said Ragaini. "Players wanted to play alongside Indy rather than becoming him, because each player has their own character that is created. Our goal was to allow them to interact with Indiana Jones like in a social experience."??

Email: Georg.Szalai@thr.com
Twitter: @georgszalai
?

Source: http://www.hollywoodreporter.com/news/lucasfilms-indiana-jones-ventures-social-266607

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US court won't block its Texas redistricting map (San Jose Mercury News)

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