New switch could improve electronics

ScienceDaily (Dec. 1, 2011) — Researchers at the University of Pittsburgh have invented a new type of electronic switch that performs electronic logic functions within a single molecule. The incorporation of such single-molecule elements could enable smaller, faster, and more energy-efficient electronics. The research findings, supported by a $1 million grant from the W.M. Keck Foundation, were published online in the Nov. 14 issue of Nano Letters.

"This new switch is superior to existing single-molecule concepts," said Hrvoje Petek, principal investigator and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. "We are learning how to reduce electronic circuit elements to single molecules for a new generation of enhanced and more sustainable technologies."

The switch was discovered by experimenting with the rotation of a triangular cluster of three metal atoms held together by a nitrogen atom, which is enclosed entirely within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation of electrons. This rotation changes the molecule's ability to conduct an electric current, thereby switching among multiple logic states without changing the spherical shape of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals.

Because of their constant spherical shape, the prototype molecular switches can be integrated as atom-like building blocks the size of one nanometer (100,000 times smaller than the diameter of a human hair) into massively parallel computing architectures.

The prototype was demonstrated using an Sc3N@C80 molecule sandwiched between two electrodes consisting of an atomically flat copper oxide substrate and an atomically sharp tungsten tip. By applying a voltage pulse, the equilateral triangle-shaped Sc3N could be rotated predictably among six logic states.

The research was led by Petek in collaboration with chemists at the Leibnitz Institute for Solid State Research in Dresden, Germany, and theoreticians at the University of Science and Technology of China in Hefei, People's Republic of China. The experiments were performed by postdoctoral researcher Tian Huang and research assistant professor Min Feng, both in Pitt's Department of Physics and Astronomy.

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Tian Huang, Jin Zhao, Min Feng, Alexey A. Popov, Shangfeng Yang, Lothar Dunsch, Hrvoje Petek. A Molecular Switch Based on Current-Driven Rotation of an Encapsulated Cluster within a Fullerene Cage. Nano Letters, 2011; : 111123145903006 DOI: 10.1021/nl2028409

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Strange new 'species' of ultra-red galaxy discovered

ScienceDaily (Dec. 1, 2011) — In the distant reaches of the universe, almost 13 billion light-years from Earth, a strange species of galaxy lay hidden. Cloaked in dust and dimmed by the intervening distance, even the Hubble Space Telescope couldn't spy it. It took the revealing power of NASA's Spitzer Space Telescope to uncover not one, but four remarkably red galaxies. And while astronomers can describe the members of this new "species," they can't explain what makes them so ruddy.

"We've had to go to extremes to get the models to match our observations," said Jiasheng Huang of the Harvard-Smithsonian Center for Astrophysics (CfA). Huang is lead author on the paper announcing the find, which was published online by the Astrophysical Journal.

Spitzer succeeded where Hubble failed because Spitzer is sensitive to infrared light -- light so red that it lies beyond the visible part of the spectrum. The newfound galaxies are more than 60 times brighter in the infrared than they are at the reddest colors Hubble can detect.

Galaxies can be very red for several reasons. They might be very dusty. They might contain many old, red stars. Or they might be very distant, in which case the expansion of the universe stretches their light to longer wavelengths and hence redder colors (a process known as redshifting). All three reasons seem to apply to the newfound galaxies.

All four galaxies are grouped near each other and appear to be physically associated, rather than being a chance line-up. Due to their great distance, we see them as they were only a billion years after the Big Bang -- an era when the first galaxies formed.

"Hubble has shown us some of the first protogalaxies that formed, but nothing that looks like this. In a sense, these galaxies might be a 'missing link' in galactic evolution" said co-author Giovanni Fazio of the CfA.

Next, researchers hope to measure an accurate redshift for the galaxies, which will require more powerful instruments like the Large Millimeter Telescope or Atacama Large Millimeter Array. They also plan to search for more examples of this new "species" of extremely red galaxies.

"There's evidence for others in other regions of the sky. We'll analyze more Spitzer and Hubble observations to track them down," said Fazio.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. NASA's Goddard Space Flight Center built Spitzer's Infrared Array Camera, which took the observations. The instrument's principal investigator is Giovanni Fazio of CfA.

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J.-S. Huang, X. Z. Zheng, D. Rigopoulou, G. Magdis, G. G. Fazio, T. Wang. FOUR IRAC SOURCES WITH AN EXTREMELY RED H – [3.6] COLOR: PASSIVE OR DUSTY GALAXIES ATz> 4.5? The Astrophysical Journal, 2011; 742 (1): L13 DOI: 10.1088/2041-8205/742/1/L13

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Using radiation to sterilize insect pests may protect California fruits and vegetables

ScienceDaily (Nov. 30, 2011) — A new study published in the Journal of Economic Entomology shows that radiation can be used to effectively sterilize the light brown apple moth (LBAM), an insect pest found in Australia, New Zealand, California, Hawaii, Sweden, and the British Isles. The light brown apple moth, Epiphyas postvittana (Walker), feeds on apples, pears, stonefruits, citrus, grapes, berries and many other plants. A native of Australia, it has been found in California since 2007. The California Department of Food and Agriculture has spent more than $70 million in CDFA and USDA funds to eradicate the LBAM, and estimates that failure to eradicate it could cost California growers over $133 million per year.

Using similar methodologies in two different laboratories, the authors coordinated radiation biology studies between two geographically isolated LBAM populations from Australia and New Zealand. The results showed that for both populations, an irradiation dose of 250 Gy administered to LBMA pupae induced >95% sterility in females and >90% sterility in males. These results can be used to initiate a suppression program against the LBMA where sterile males are released, mate with wild females, and no offspring are produced. If successful, this technique can largely eliminate the need for pesticides.

"These results suggest that a sterile insect technique (SIT) or F1 sterility program can be applied to control an infestation of Epiphyas postvittana, but these would still be reliant on complementary information such as physical fitness and modeling of overflooding ratios." according to the authors. "The challenge now is to identify the dose of radiation that would provide a balance between insect sterility and field competitiveness."

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Rajendra Soopaya, Lloyd D. Stringer, Bill Woods, Andrea E. A. Stephens, Ruth C. Butler, Ian Lacey, Amandip Kaur, and David M. Suckling. Radiation Biology and Inherited Sterility of Light Brown Apple Moth (Lepidoptera: Tortricidae): Developing a Sterile Insect Release Program. J. Econ. Entomol., 104(6): 1999?2008 (2011) DOI: 10.1603/EC11049

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China's demand for oil will equal US demand by 2040

ScienceDaily (Dec. 1, 2011) — Despite aggressive demand-management policies announced in recent years, China's oil use could easily reach levels comparable to today's U.S. levels by 2040, according to a new energy study by the Baker Institute.

The study's authors said this finding has timely significance because China's growing energy use could continue to pose a major challenge for global climate deliberations in South Africa this week.

The study, "The Rise of China and Its Energy Implications," finds that China's recent efforts at centralizing energy policy do not appear to be significantly more successful than the makeshift patchwork of energy initiatives devised by the United States. In fact, the study said, the U.S. system of open and competitive private sector investment is stimulating more innovation in the American energy sector than in the Chinese energy industry, especially in the area of unconventional oil and gas.

That, ironically, is attracting Chinese state investment to U.S. shores and prompting Beijing to consider further opening of its oil and gas exploration activities to partnerships with U.S. firms, the study said.

China, like the United States, has substantial potential shale gas resources but faces technical, regulatory and market infrastructure challenges that are likely to delay rapid development. Were China to mobilize investments in shale gas more quickly, the study said, it could greatly reduce the country's expected large import needs for liquefied natural gas (LNG) from Australia and the Middle East and contribute to a future glut in global natural gas markets.

Despite sporadic government policies to discourage private car ownership, the growth in the number of vehicles on the road in China has more than quadrupled in recent years to more than 50 million. The Baker Institute report projects that this number could increase to more than 200 million vehicles by 2020 and 770 million by 2040 under a scenario where China's real gross domestic product growth averages 6 percent between now and 2030. Even under a scenario where the number of electric cars rises to 5 million a year by 2030, which is in line with ambitious targets announced by China's National Development and Reform Commission, China's oil use from the transportation sector will grow significantly, the Baker Institute study said.

"Given the scale of vehicle stock growth in China, it is going to be extremely difficult to move the needle of the country's rising transport fuel outlook," said Kenneth Medlock, a study author and the James A. Baker III and Susan G. Baker Fellow in Energy and Resource Economics at the Baker Institute.

The study noted that China's "going abroad" strategy has also encountered recent difficulties in light of geopolitical events and rising global political risks in oil-producing regions.

"China is learning that owning equity oil in risky regions may not be as effective an energy security strategy as it had previously imagined," said Amy Myers Jaffe, an author of the study and the Wallace S. Wilson Fellow for Energy Studies at the Baker Institute. "China is now finding itself mired in more energy-related foreign diplomacy than it bargained for.

"But this could be good news for the United States," Jaffe said. "It may mean China will be more inclined to act in concert with other members of the international community in conflict-prone regions."

The study noted that China has tried to offset some of this risk by increasing investments in the United States and Canada, which gives the U.S. more leverage in seeking China's collaboration in international diplomatic matters.

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NASA's Swift finds a gamma-ray burst with a dual personality

ScienceDaily (Nov. 30, 2011) — A peculiar cosmic explosion first detected by NASA's Swift observatory on Christmas Day 2010 was caused either by a novel type of supernova located billions of light-years away or an unusual collision much closer to home, within our own galaxy. Papers describing both interpretations appear in the Dec. 1 issue of the journal Nature.

Gamma-ray bursts (GRBs) are the universe's most luminous explosions, emitting more energy in a few seconds than our sun will during its entire energy-producing lifetime. What astronomers are calling the "Christmas burst" is so unusual that it can be modeled in such radically different ways.

"What the Christmas burst seems to be telling us is that the family of gamma-ray bursts is more diverse than we fully appreciate," said Christina Thoene, the supernova study's lead author, at the Institute of Astrophysics of Andalusia in Granada, Spain. It's only by rapidly detecting hundreds of them, as Swift is doing, that we can catch some of the more eccentric siblings."

Common to both scenarios is the presence of a neutron star, the crushed core that forms when a star many times the sun's mass explodes. When the star's fuel is exhausted, it collapses under its own weight, compressing its core so much that about a half-million times Earth's mass is squeezed into a sphere no larger than a city.

The Christmas burst, also known as GRB 101225A, was discovered in the constellation Andromeda by Swift's Burst Alert Telescope at 1:38 p.m. EST on Dec. 25, 2010. The gamma-ray emission lasted at least 28 minutes, which is unusually long. Follow-up observations of the burst's afterglow by the Hubble Space Telescope and ground-based observatories were unable to determine the object's distance.

Thoene's team proposes that the burst occurred in an exotic binary system where a neutron star orbited a normal star that had just entered its red giant phase, enormously expanding its outer atmosphere. This expansion engulfed the neutron star, resulting in both the ejection of the giant's atmosphere and rapid tightening of the neutron star's orbit.

Once the two stars became wrapped in a common envelope of gas, the neutron star may have merged with the giant's core after just five orbits, or about 18 months. The end result of the merger was the birth of a black hole and the production of oppositely directed jets of particles moving at nearly the speed of light, followed by a weak supernova.

The particle jets produced gamma rays. Jet interactions with gas ejected before the merger explain many of the burst's signature oddities. Based on this interpretation, the event took place about 5.5 billion light-years away, and the team has detected what may be a faint galaxy at the right location.

"Deep exposures using Hubble may settle the nature of this object," said Sergio Campana, who led the collision study at Brera Observatory in Merate, Italy.

If it is indeed a galaxy, that would be evidence for the binary model. On the other hand, if NASA's Chandra X-ray Observatory finds an X-ray point source or if radio telescopes detect a pulsar, that goes against it.

Campana's team supports an alternative model that involves the tidal disruption of a large comet-like object and the ensuing crash of debris onto a neutron star located only about 10,000 light-years away. The scenario requires the break-up of an object with about half the mass of the dwarf planet Ceres. While rare in the asteroid belt, such objects are thought to be common in the icy Kuiper belt beyond Neptune. Similar objects located far away from the neutron star may have survived the supernova that formed it.

Gamma-ray emission occurred when debris fell onto the neutron star. Clumps of cometary material likely made a few orbits, with different clumps following different paths before settling into a disk around the neutron star. X-ray variations detected by Swift's X-Ray Telescope that lasted several hours may have resulted from late-arriving clumps that struck the neutron star as the disk formed.

In the early years of studying GRBs, astronomers had very few events to study in detail and dozens of theories to explain them. In the Swift era, astronomers have settled into two basic scenarios, either the collapse of a massive star or the merger of a compact binary system.

"The beauty of the Christmas burst is that we must invoke two exotic scenarios to explain it, but such rare oddballs will help us advance the field," said Chryssa Kouveliotou, a co-author of the supernova study at NASA's Marshall Space Flight Center in Huntsville, Ala.

NASA's Swift was launched in November 2004 and is managed by Goddard. It is operated in collaboration with several U.S. institutions and partners in the United Kingdom, Italy, Germany and Japan.

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Journal References:

C. C. Thöne, A. de Ugarte Postigo, C. L. Fryer, K. L. Page, J. Gorosabel, M. A. Aloy, D. A. Perley, C. Kouveliotou, H. T. Janka, P. Mimica, J. L. Racusin, H. Krimm, J. Cummings, S. R. Oates, S. T. Holland, M. H. Siegel, M. De Pasquale, E. Sonbas, M. Im, W.-K. Park, D. A. Kann, S. Guziy, L. Hernández García, A. Llorente, K. Bundy, C. Choi, H. Jeong, H. Korhonen, P. Kubànek, J. Lim, A. Moskvitin, T. Muñoz-Darias, S. Pak, I. Parrish. The unusual ?-ray burst GRB 101225A from a helium star/neutron star merger at redshift 0.33. Nature, 2011; 480 (7375): 72 DOI: 10.1038/nature10611S. Campana, G. Lodato, P. D’Avanzo, N. Panagia, E. M. Rossi, M. Della Valle, G. Tagliaferri, L. A. Antonelli, S. Covino, G. Ghirlanda, G. Ghisellini, A. Melandri, E. Pian, R. Salvaterra, G. Cusumano, V. D’Elia, D. Fugazza, E. Palazzi, B. Sbarufatti, S. D.Vergani. The unusual gamma-ray burst GRB 101225A explained as a minor body falling onto a neutron star. Nature, 2011; 480 (7375): 69 DOI: 10.1038/nature10592

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Age-old remedies using white tea, witch hazel and rose may be beneficial, study suggests

ScienceDaily (Dec. 1, 2011) — Age-old remedies could hold the key to treating a wide range of serious medical problems, as well as keeping skin firmer and less wrinkled, according to scientists from London's Kingston University. A collaboration between the university and British beauty brand Neal's Yard Remedies has seen experts discover that white tea, witch hazel and the simple rose hold potential health and beauty properties which could be simply too good to ignore.

The research suggests a number of naturally-occurring substances may offer the hope of new treatments to block the progression of inflammation. It is credited with a major role in both the initiation and development of diseases ranging from cancer, diabetes and arthritis through to neuro-degenerative conditions and cardiovascular and pulmonary problems.

"For thousands of years people used natural remedies to try -- and sometimes succeed -- in curing their ailments and preserving their youth," Professor Declan Naughton, from the University's School of Life Sciences, said. "Now the latest research we have carried out suggests a number of naturally-occurring substances may offer the hope of new treatments to block the progression of inflammation."

Inflammation is credited with a major role in both the initiation and development of diseases ranging from cancer, diabetes and arthritis through to neuro-degenerative conditions and cardiovascular and pulmonary problems. It is also implicated in premature aging and early death. "Inflammation is a secret killer -- helping arrest its development, or being able to stop it happening at all, would clearly be of benefit," Professor Naughton explained.

The new study builds on work undertaken by Professor Naughton and Kingston University PhD student Tamsyn Thring, along with the technical team from Neal's Yard. They tested 21 plant extracts for evidence of their efficiency in fighting cancer and also in the battle against aging. Of the 21 extracts, three -- white tea, witch hazel and rose -- showed considerable potential, with white tea displaying the most marked results. "Indeed it appeared that drinking a simple cup of white tea might well help reduce an individual's risk of cancer, rheumatoid arthritis or even just age-associated wrinkles," Professor Naughton said.

Spurred on by their laboratory findings, the team members decided to take the work further to see if they could replicate the results in human skin cells, looking more closely at the anti-inflammatory and anti-oxidant activity of the three extracts.

Using human skin cells as their model, the researchers added three different concentrations of white tea (freeze dried powder), witch hazel (dried herb) and rose extract (in a medicinal tincture form) to see what effect the mixtures might have on suppressing rogue enzymes and oxidants which play a key role in helping inflammation develop, as well as aging the skin. "As the largest organ in the body, the skin provides a barrier against UV radiation, chemicals, microbes and physical pollutants," Ms Thring said. "Challenges like this can contribute to both inflammation and skin aging.

"We also know that when inflammation starts -- be it a simple cut to a finger or in an arthritic joint -- the body starts producing a compound called interleukin 8, which helps the process along. We began wondering if there was a way we could switch that signal off, thereby blocking the inflammation's progress."

Even though the team's previous research had intimated there might be some promising results ahead, the experts were astonished to see just how good the various concentrations of the three extracts were at doing the job.

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Tamsyn SA Thring, Pauline Hili, Declan P Naughton. Antioxidant and potential anti-inflammatory activity of extracts and formulations of white tea, rose, and witch hazel on primary human dermal fibroblast cells. Journal of Inflammation, 2011; 8 (1): 27 DOI: 10.1186/1476-9255-8-27

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Timing is everything: Bacterial attachment mimics just-in-time industrial model

ScienceDaily (Nov. 30, 2011) — n the human world of manufacturing, many companies are now applying an on-demand, just-in-time strategy to conserve resources, reduce costs and promote production of goods precisely when and where they are most needed. A recent study from Indiana University Bloomington scientists reveals that bacteria have evolved a similar just-in-time strategy to constrain production of an extremely sticky cement to exactly the appropriate time and place, avoiding wasteful and problematic production of the material.

Indiana University biologists and two physicists at Brown University with IU connections have shown that certain bacteria wait until the last minute to synthesize the glue that allows them to attach permanently to surfaces. Binding efficiently to surfaces is extremely important to bacteria in the environment and for bacterial disease agents during the infection process.

The researchers found that bacteria -- including the freshwater bacterium Caulobacter crescentus and the agricultural pathogen Agrobacterium tumefaciens -- first connect to a surface with the cellular equivalents of propellers and cables and that this initial, reversible contact stimulates the synthesis of a sticky glue. This holdfast adhesin, which is composed of polysaccharide sugar molecules, is then released only at the site of surface contact to irreversibly attach the bacteria to host surfaces.

The study, "Surface contact stimulates the just-in-time deployment of bacterial adhesins," was published earlier this month in Molecular Microbiology . It describes how single bacterial cells use their flagella (the propellers) and pili (the cables) to facilitate the timely release of adhesive polysaccharides upon initial contact with other surfaces.

Microbiologists are generally interested in bacterial adhesion and formation of complex microbial communities called biofilms that can clog pipes, slow down ships and establish antibiotic-resistant infections. Efficient surface attachment strategies are advantageous to bacteria as they can increase nutrient access and resistance to environmental stress, including host defenses.

"For bacteria, surface attachment by single cells is the first step to important processes such as biofilm formation and host infection," said IU microbiologist Pamela Brown, one of the project's lead authors. "What we found is that the interaction of bacterial cells with a surface using their flagellum and pili stimulates the on-the-spot production of polysaccharide adhesins, propelling the transition from transient to permanent attachment."

The new findings also suggest that pathogenic bacteria may carefully time adhesin release to protect themselves from premature exposure to a host's immune system during infection.

The team used cutting-edge, high-resolution video microscopy to observe the single-cell attachment process in real time in the presence of a fluorescent stain that decorates the adhesive polysaccharide. They found that when Caulobacter cells are propelled to a surface by their rotating propeller-like single flagellum, the flagellar motor stopped immediately upon contact with the surface. Inhibition of flagellar rotation was quickly followed by the production of the holdfast polysaccharide adhesin, specifically from the cell pole containing the now inactive flagellum, and in contact with the surface.

"We knew that cable-like pili are present at the same pole of the cell as the flagellum, and we hypothesized that they played a key role in the process by interacting with the surface, thereby preventing the free rotation of the flagellum," said IU microbiologist Yves Brun, the project's principal investigator. Indeed, when the team made a mutation that abolished the pili, the cells became tethered to the surface by their flagellum, but its rotation continued and the cell eventually detached.

The team hypothesizes that just-in-time adhesin production may be a general phenomenon since they obtained similar results with two other bacterial species, Agrobacterium tumefaciens and Asticcacaulis biprosthecum.

"What is striking is that we found that this mechanism does more than stimulate binding to inert surfaces. It also operates when the plant pathogen Agrobacterium tumefaciens binds to host tissue," said IU microbiologist Clay Fuqua, who recently discovered the holdfast-type adhesin used by this bacterium to attach to plant tissue. "We think that the ability to rapidly deploy this permanent adhesin may be advantageous for swimming cells attempting to colonize a favorable environment."

Since pathogens such as Escherichia coli and Pseudomonas aeruginosa also attach by their pole prior to their transition from reversible to irreversible attachment, the authors hypothesize that this mechanism could also be at play during the infection process.

"Once we know more about the details of this mechanism, we may be able to design drugs that prevent this adhesin stimulation, therefore reducing the efficiency of infections," Brown said.

Research from Brun's laboratory and that of Brown University physicist Jay Tang on bacterial glues published in 2006 received international attention after they showed that the holdfast "glue" released by the tiny Caulobacter cells was the strongest in nature with a pulling force of 1 micronewton, equivalent to holding three or four cars with glue spread on the surface of a quarter.

"For such a strong adhesive, it may be important to avoid producing it too early because it might lose its efficiency, or it might get the cells irreversibly bound to the wrong surface. The analogy to the human world is amazing: You don't apply glue hours before you want to use it because it cures and hardens," Brun said.

Timing is everything, and with just-in-time adhesive production, cells have a better chance for efficient surface interaction and colonization because the two main factors in reducing adhesion -- curing and coating of glue with small particles -- are inhibitory mechanisms that require time to decrease adhesiveness. The on-the-spot production of adhesins circumvents this problem.

Funding for this research was provided by the National Institutes of Health, the Indiana University Faculty Research Support Program and the Indiana METACyt Initiative of IU.

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Guanglai Li, Pamela J. B. Brown, Jay X. Tang, Jing Xu, Ellen M. Quardokus, Clay Fuqua, Yves V. Brun. Surface contact stimulates the just-in-time deployment of bacterial adhesins. Molecular Microbiology, 2011; DOI: 10.1111/j.1365-2958.2011.07909.x

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