SCIENCE TECHNOLOGY

Astronomers Report That Dark Matter 'Halos' May Contain Stars, Disprove Other Theories

2012-10-28T22:09:00.000-07:00

Could it be that dark matter "halos" -- the huge, invisible cocoons of mass that envelop entire galaxies and account for most of the matter in the universe -- aren't completely dark after all but contain a small number of stars? Astronomers from UCLA, UC Irvine and elsewhere make a case for that in the Oct. 25 issue of the journal Nature.

Astronomers have long disagreed about why they see more light in the universe than it seems they should -- that is, why the infrared light they observe exceeds the amount of light emitted from known galaxies.

When looking at the cosmos, astronomers have seen what are neither stars nor galaxies nor a uniform dark sky but mysterious, sandpaper-like smatterings of light, which UCLA's Edward L. (Ned) Wright refers to as "fluctuations." The debate has centered around what exaclty the source of those fluctuations is.

One explanation is that the fluctuations in the background are from very distant unknown galaxies. A second is that they're from unknown galaxies that are not so far away, faint galaxies whose light has been traveling to us for only 4 billion or 5 billion years (a rather short time in astronomy terms). In the Nature paper, Wright and his colleagues present evidence that both these explanations are wrong, and they propose an alternative.

The first explanation -- that the fluctuations are from very distant galaxies -- is nowhere close to being supported by the data the astronomers present from NASA's Spitzer Space Telescope, said Wright, a UCLA professor of physics and astronomy.

"The idea of not-so-far-away faint galaxies is better, but still not right," he added. "It's off by a factor of about 10; the 'distant galaxies' hypothesis is off by a factor of about 1,000."

Wright and his colleagues, including lead author Asantha Cooray, a UC Irvine professor of physics and astronomy, contend that the small number of stars that were kicked to the edges of space during violent collisions and mergers of galaxies may be the cause of the infrared light "halos" across the sky and may explain the mystery of the excess emitted infrared light.

As crashing galaxies became gravitationally tangled with one another, "orphaned" stars were tossed into space. It is these stars, the researchers say, that produce the diffuse, blotchy scatterings of light emitted from the galaxy halos that extend well beyond the outer reaches of galaxies.

"Galaxies exist in dark matter halos that are much bigger than the galaxies; when galaxies form and merge together, the dark matter halo gets larger and the stars and gas sink to the middle of the the halo," said Wright, who holds UCLA's David Saxon Presidential Chair in Physics. "What we're saying is one star in a thousand does not do that and instead gets distributed like dark matter. You can't see the dark matter very well, but we are proposing that it actually has a few stars in it -- only one-tenth of 1 percent of the number of stars in the bright part of the galaxy. One star in a thousand gets stripped out of the visible galaxy and gets distributed like the dark matter.

"The dark matter halo is not totally dark," Wright said. "A tiny fraction, one-tenth of a percent, of the stars in the central galaxy has been spread out into the halo, and this can produce the fluctuations that we see."

In large clusters of galaxies, astronomers have found much higher percentages of intra-halo light, as large as 20 percent, Wright said.

For this study, Cooray, Wright and colleagues used the Spitzer Space Telescope to produce an infrared map of a region of the sky in the constellation Boötes. The light has been travelling to us for 10 billion years.

"Presumably this light in halos occurs everywhere in the sky and just has not been measured anywhere else," said Wright, who is also principal investigator of NASA's Wide-field Infrared Survey Explorer (WISE) mission.

"If we can really understand the origin of the infrared background, we can understand when all of the light in the universe was produced and how much was produced," Wright said. "The history of all the production of light in the universe is encoded in this background. We're saying the fluctuations can be produced by the fuzzy edges of galaxies that existed at the same time that most of the stars were created, about 10 billion years ago."

The research was funded by the National Science Foundation, NASA and NASA's Jet Propulsion Laboratory.

Future research, especially with the James Webb Space Telescope, should provide further insights, Wright said.

"What we really need to be able to do is to see and identify the galaxies that are producing all the light in the infrared background," he said. "That could be done to a much greater extent once the James Webb Space Telescope is operational because it will be able to see much more distant, fainter galaxies."

Journal Reference:

Asantha Cooray, Joseph Smidt, Francesco De Bernardis, Yan Gong, Daniel Stern, Matthew L. N. Ashby, Peter R. Eisenhardt, Christopher C. Frazer, Anthony H. Gonzalez, Christopher S. Kochanek, Szymon Kozłowski, Edward L. Wright. Near-infrared background anisotropies from diffuse intrahalo light of galaxies. Nature, 2012; 490 (7421): 514

Enough Wind to Power Global Energy Demand: New Research Examines Limits, Climate Consequences

2012-09-15T20:37:00.000-07:00

There is enough energy available in winds to meet all of the world's demand. Atmospheric turbines that convert steadier and faster high-altitude winds into energy could generate even more power than ground- and ocean-based units. New research from Carnegie's Ken Caldeira examines the limits of the amount of power that could be harvested from winds, as well as the effects high-altitude wind power could have on the climate as a whole.

Their work is published September 9 by Nature Climate Change.

Led by Kate Marvel of Lawrence Livermore National Laboratory, who began this research at Carnegie, the team used models to quantify the amount of power that could be generated from both surface and atmospheric winds. Surface winds were defined as those that can be accessed by turbines supported by towers on land or rising out of the sea. High-altitude winds were defined as those that can be accessed by technology merging turbines and kites. The study looked only at the geophysical limitations of these techniques, not technical or economic factors.

Turbines create drag, or resistance, which removes momentum from the winds and tends to slow them. As the number of wind turbines increase, the amount of energy that is extracted increases. But at some point, the winds would be slowed so much that adding more turbines will not generate more electricity. This study focused on finding the point at which energy extraction is highest.

Using models, the team was able to determine that more than 400 terawatts of power could be extracted from surface winds and more than 1,800 terawatts could be generated by winds extracted throughout the atmosphere.

Today, civilization uses about 18 TW of power. Near-surface winds could provide more than 20 times today's global power demand and wind turbines on kites could potentially capture 100 times the current global power demand.

At maximum levels of power extraction, there would be substantial climate effects to wind harvesting. But the study found that the climate effects of extracting wind energy at the level of current global demand would be small, as long as the turbines were spread out and not clustered in just a few regions. At the level of global energy demand, wind turbines might affect surface temperatures by about 0.1 degree Celsius and affect precipitation by about 1%. Overall, the environmental impacts would not be substantial.

"Looking at the big picture, it is more likely that economic, technological or political factors will determine the growth of wind power around the world, rather than geophysical limitations," Caldeira said.

Length of Yellow Caution Traffic Lights Could Prevent Accidents, Researchers Say

2012-09-14T12:03:00.000-07:00

A couple of years ago, Hesham Rakha misjudged a yellow traffic light and entered an intersection just as the light turned red. A police officer handed him a ticket.

"There are circumstances, as you approach a yellow light, where the decision is easy. If you are close to the intersection, you keep going. If you are far away, you stop. If you are almost at the intersection, you have to keep going because if you try to stop, you could cause a rear-end crash with the vehicle behind you and would be in the middle of the intersection anyway," said Rakha, professor of civil and environmental engineering at Virginia Tech.

He's not trying to defend his action. Rakha, director of the Center for Sustainable Mobility (www.vtti.vt.edu/csm.php) at the Virginia Tech Transportation Institute (www.vtti.vt.edu), is describing his research. Since 2005, his research group has been studying drivers' behaviors as they approach yellow lights. Their goal is to determine signal times for intersections that are safer and still efficient.

If a driver decides to stop when instead of proceeding, rear-end crashes could occur. If a driver proceeds instead of stopping, collisions with side street traffic could occur. Although observation-based research shows that only 1.4 percent of drivers cross the stop line after the light turns red, more than 20 percent of traffic fatalities in the United States occur at intersections.

"If the yellow time is not set correctly, a dilemma zone is eminent," Rakha said.

"The dilemma zone occurs when the driver has no feasible choice," he said. "In other words the driver can neither stop nor proceed through the intersection before the light turns red. This can also occur if the approaching vehicle is traveling faster than the posted speed limit and/or if the driver's perception and reaction time is longer than the design one-second value."

In most cases, the yellow time is set for 4.2 seconds on a 45 mph road. The time is longer for higher-speed roads. "These timings are based on two assumptions," Rakha explains. "Namely, the driver requires one second to perceive and react to the change in signal indication and that the driver requires 3.2 seconds to stop from 45 mph at a comfortable deceleration level, assumed to be 3 meters per second squared (3 m/s2 ) or 10 feet per second squared."

For his studies, Rakha's used Virginia's Smart Road, located at the Virginia Tech Transportation Institute. The Smart Road intersection has a signal that can be controlled for length of the red, yellow and green lights. "We can study driver behavior by changing the signal when the driver is a certain distance from the intersection."

Center for Sustainable Mobility researchers have determined that half of drivers make the stop-go decision three seconds before the stop line. Of those that go, few clear the intersection before the light changes to red. In Virginia, if you are in the intersection when the light turns red, you are not running a red light. However, there is still risk.

The specific findings from the Smart Road study are that 43 percent of drivers who crossed the stop line during the yellow time were not able to clear the intersection before the light turned red. At 45 mph, it takes 1.5 seconds to clear a 30-meter (98.4 feet) intersection. "If the all-red interval is the minimum conventional one second, then there is a potential risk that the legal yellow-light runners would not be able to completely clear the intersection at the instant the side-street traffic gains the right-of-way," the researchers reported at the Transportation Research Board Annual Meeting in 2010.

People over 60 years of age have a longer perception-reaction time, so they have to brake harder to stop. But they are more likely to try to stop, compared to younger drivers. However, if they keep going, they are unlikely to clear the intersection, the researchers report.

"Even if yellow timing is designed properly to avoid a dilemma zone, someone driving above the speed limit could encounter a dilemma because it takes longer to stop from a higher speed. They could speed up, but our studies show that drivers who keep going usually maintain their speed," Rakha said.

The research determined that the perception-reaction time is slightly longer than one second, but that driver deceleration levels are significantly higher than the deceleration level assumed for traffic signal design.

If the road conditions are poor, drivers react 15 percent slower because they are processing more information. Deceleration level decreases by 8 percent. "In such conditions, you need a longer yellow," Rakha said.

He and his team has developed a novel procedure to compute the yellow and change interval duration that accounts for the risk of drivers being caught in the dilemma zone. Using this procedure they have created tables for light vehicles at various speeds for dry roads and wet roads, so that traffic planners can set traffic signals that can be adjusted to roadway surface and weather conditions. They also created tables for the driving characteristics for different age groups.

One strategy to make intersections safer might be more use of caution lights that tell drivers a green light is about to change, so the driver has a longer time to react. Such systems now are used on high speed roads, where the stopping distance is longer, and when the lighted intersection is not visible until the last seconds.

A future strategy that researchers are investigating is in-car display systems that can be customized to each driver's reaction time. "So one person receives a four-second warning of a light change, and another person receives a five-second warning. Or, instead of a warning, the system might just tell you to stop," said Rakha.

Research to implement vehicle-to-vehicle and infrastructure-to-vehicle communication is ongoing, including at the Virginia Tech Transportation Institute Tier 1 University Transportation Center. Rakha's research group is studying vehicle-to-vehicle communication at intersections.

The research has been presented at the 2010 and 2011 Transportation Research Board annual meetings. Articles published in 2012 are:

"Novel Stochastic Procedure for Designing Yellow Intervals at Signalized Intersections," by Ahmed Amer, transportation engineer with Vanasse Hangen Brustlin Inc.; Rakha; and Ihab El- Shawarby, assistant professor at Ain-Shams University in Cairo and senior research associate with the Center for Sustainable Mobility at the Virginia Tech Transportation Institute. It appeared in the June 1, 2012, Journal of Transportation Engineering.

"Designing Yellow Intervals for Rainy and Wet Roadway Conditions," by Huan Li of Blacksburg, who has received his master of science degree in civil engineering; Rakha; and El-Shawarby. The article appeared in the spring 2012 issue of theInternational Journal of Transportation Science and Technology.

NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars

2012-09-08T23:49:00.000-07:00

Coming less than a year after the announcement of the first circumbinary planet, Kepler-16b, NASA's Kepler mission has discovered multiple transiting planets orbiting two suns for the first time. This system, known as a circumbinary planetary system, is 4,900 light-years from Earth in the constellation Cygnus.

This discovery proves that more than one planet can form and persist in the stressful realm of a binary star and demonstrates the diversity of planetary systems in our galaxy.

Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright.

"In contrast to a single planet orbiting a single star, the planet in a circumbinary system must transit a 'moving target.' As a consequence, time intervals between the transits and their durations can vary substantially, sometimes short, other times long," said Jerome Orosz, associate professor of astronomy at San Diego State University and lead author of the paper. "The intervals were the telltale sign these planets are in circumbinary orbits."

The inner planet, Kepler-47b, orbits the pair of stars in less than 50 days. While it cannot be directly viewed, it is thought to be a sweltering world, where the destruction of methane in its super-heated atmosphere might lead to a thick haze that could blanket the planet. At three times the radius of Earth, Kepler-47b is the smallest known transiting circumbinary planet.

The outer planet, Kepler-47c, orbits its host pair every 303 days, placing it in the so-called "habitable zone," the region in a planetary system where liquid water might exist on the surface of a planet. While not a world hospitable for life, Kepler-47c is thought to be a gaseous giant slightly larger than Neptune, where an atmosphere of thick bright water-vapor clouds might exist.

"Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been -- do they have planets and planetary systems? This Kepler discovery proves that they do," said William Borucki, Kepler mission principal investigator at NASA's Ames Research Center in Moffett Field, Calif. "In our search for habitable planets, we have found more opportunities for life to exist."

To search for transiting planets, the research team used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars. Additional ground-based spectroscopic observations using telescopes at the McDonald Observatory at the University of Texas at Austin helped characterize the stellar properties. The findings are published in the journal Science.

"The presence of a full-fledged circumbinary planetary system orbiting Kepler-47 is an amazing discovery," said Greg Laughlin, professor of Astrophysics and Planetary Science at the University of California in Santa Cruz. "These planets are very difficult to form using the currently accepted paradigm, and I believe that theorists, myself included, will be going back to the drawing board to try to improve our understanding of how planets are assembled in dusty circumbinary disks."

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development.

Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's tenth Discovery Mission and funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

Standoff Sensing Enters New Realm With Dual-Laser Technique

2012-04-07T09:30:00.000-07:00

Identifying chemicals from a distance could take a step forward with the introduction of a two-laser system being developed at the Department of Energy's Oak Ridge National Laboratory.

In a paper published in the Journal of Physics D: Applied Physics, Ali Passian and colleagues present a technique that uses a quantum cascade laser to "pump," or strike, a target, and another laser to monitor the material's response as a result of temperature-induced changes. That information allows for the rapid identification of chemicals and biological agents.

"With two lasers, one serves as the pump and the other is the probe," said Passian, a member of ORNL's Measurement Science and Systems Engineering Division. "The novel aspect to our approach is that the second laser extracts information and allows us to do this without resorting to a weak return signal.

"The use of a second laser provides a robust and stable readout approach independent of the pump laser settings."

While this approach is similar to radar and lidar sensing techniques in that it uses a return signal to carry information of the molecules to be detected, it differs in a number of ways.

"First is the use of photothermal spectroscopy configuration where the pump and probe beams are nearly parallel," Passian said. "We use probe beam reflectometry as the return signal in standoff applications, thereby minimizing the need for wavelength-dependent expensive infrared components such as cameras, telescopes and detectors."

This work represents a proof of principle success that Passian and co-author Rubye Farahi said could lead to advances in standoff detectors with potential applications in quality control, forensics, airport security, medicine and the military. In their paper, the researchers also noted that measurements obtained using their technique may set the stage for hyperspectral imaging.

"This would allow us to effectively take slices of chemical images and gain resolution down to individual pixels," said Passian, who added that this observation is based on cell-by-cell measurements obtained with their variation of photothermal spectroscopy. Hyperspectral imaging provides not only high-resolution chemical information, but topographical information as well.

Other authors are ORNL's Laurene Tetard, a Wigner Fellow, and Thomas Thundat of the University of Alberta. Funding for this research was provided by ORNL's Laboratory Directed Research and Development program.

Swarming and Transporting

2012-04-06T09:30:00.000-07:00

On its own, an ant is not particularly clever. But in a community, the insects can solve complicated tasks. Researchers intend to put this "swarm intelligence" to use in the logistics field. Lots of autonomous transport shuttles would provide an alternative to traditional materials-handling technology.

The orange-colored vehicle begins moving with a quiet whirr. Soon afterwards the next shuttles begin to move, and before long there are dozens of mini-transporters rolling around in the hall. As if by magic, they head for the high-rack storage shelves or spin around their own axis. But the Multishuttle Moves® -- is the name given to these driverless transport vehicles -- are not performing some robots' ballet. They are moving around in the service of science. At the Fraunhofer Institute for Material Flow and Logistics IML in Dortmund, Germany, researchers are working to harness swarm intelligence as a means of improving the flow of materials and goods in the warehouse environment. In a research hall 1000 square meters in size, the scientists have replicated a small-scale distribution warehouse with storage shelves for 600 small-part carriers and eight picking stations. The heart of the testing facility is a swarm of 50 autonomous vehicles. "In the future, transport systems should be able to perform all of these tasks autonomously, from removal from storage at the shelf to delivery to a picking station. This will provide an alternative to conventional materials-handling solutions," explains Prof. Dr. Michael ten Hompel, executive director at IML.

But how do the vehicles know what they should transport, and where, and which of the 50 shuttles will take on any particular order? "The driverless transport vehicles are locally controlled. The ›intelligence‹ is in the transporters themselves," Dipl.-Ing. Thomas Albrecht, head of the Autonomous Transport Systems department explains the researchers' solution approach. "We rely on agent-based software and use ant algorithms based on the work of Marco Dorigo. These are methods of combinational optimization based on the model behavior of real ants in their search for food." When an order is received, the shuttles are informed of this through a software agent. They then coordinate with one another via WLAN to determine which shuttle can take over the load. The job goes to whichever free transport system is closest.

The shuttles are completely unimpeded as they navigate throughout the space -- with no guidelines. Their integrated localization and navigation technology make this possible. The vehicles have a newly developed, hybrid sensor concept with signal-based location capability, distance and acceleration sensors and laser scanners. This way, the vehicles can compute the shortest route to any destination. The sensors also help prevent collisions.

The vehicles are based on the components of the shelf-bound Multishuttle already successfully in use for several years. The researchers at IML have worked with colleagues at Dematic to develop the system further. The special feature about the Multishuttle Move®: the transporters can navigate in the storage area and in the hall. To accomplish this, the shuttles are fitted with an additional floor running gear. But what benefits do these autonomous transporters offer compared with conventional steady materials-handling technology with roller tracks? "The system is considerably more flexible and scalable," Albrecht points out. It can grow or contract depending on the needs at hand. This is how system performance can be adapted to seasonal and daily fluctuation. Another benefit: It considerably shortens transportation paths. In conventional storage facilities, materials-handling equipment obstructs the area between high-rack storage and picking stations. Packages must travel two to three times farther than the direct route. "It also makes shelf-control units and steady materials-handling technology," Albrecht adds. Researchers are now trying to determine how these autonomous transporters can improve intralogistics. "We want to demonstrate that cellular materials-handling technology makes sense not only technically but also economically as an alternative to classic materials-handling technology and shelf-control units," institute executive director ten Hompel observes. If this succeeds, the autonomous vehicles could soon be going into service in warehouses.

New Theory On Size of Black Holes: Gas-Guzzling Black Holes Eat Two Courses at a Time

2012-04-05T09:29:00.000-07:00

Astronomers have put forward a new theory about why black holes become so hugely massive -- claiming some of them have no 'table manners', and tip their 'food' directly into their mouths, eating more than one course simultaneously.

Researchers from the UK and Australia investigated how some black holes grow so fast that they are billions of times heavier than the sun.

The team from the University of Leicester (UK) and Monash University in Australia sought to establish how black holes got so big so fast.

Professor Andrew King from the Department of Physics and Astronomy, University of Leicester, said: "Almost every galaxy has an enormously massive black hole in its center. Our own galaxy, the Milky Way, has one about four million times heavier than the sun. But some galaxies have black holes a thousand times heavier still. We know they grew very quickly after the Big Bang.''

"These hugely massive black holes were already full--grown when the universe was very young, less than a tenth of its present age."

Black holes grow by sucking in gas. This forms a disc around the hole and spirals in, but usually so slowly that the holes could not have grown to these huge masses in the entire age of the universe. `We needed a faster mechanism,' says Chris Nixon, also at Leicester, "so we wondered what would happen if gas came in from different directions."

Nixon, King and their colleague Daniel Price in Australia made a computer simulation of two gas discs orbiting a black hole at different angles. After a short time the discs spread and collide, and large amounts of gas fall into the hole. According to their calculations black holes can grow 1,000 times faster when this happens.

"If two guys ride motorbikes on a Wall of Death and they collide, they lose the centrifugal force holding them to the walls and fall," says King. The same thing happens to the gas in these discs, and it falls in towards the hole.

This may explain how these black holes got so big so fast. "We don't know exactly how gas flows inside galaxies in the early universe," said King, "but I think it is very promising that if the flows are chaotic it is very easy for the black hole to feed."

The two biggest black holes ever discovered are each about ten billion times bigger than the Sun.

Their research is due to published in the Monthly Notices of the Royal Astronomical Society. The research was funded by the UK Science and Technology Facilities Council.

Shiny New Tool for Imaging Biomolecules

2012-04-04T09:27:00.000-07:00

At the heart of the immune system that protects our bodies from disease and foreign invaders is a vast and complex communications network involving millions of cells, sending and receiving chemical signals that can mean life or death. At the heart of this vast cellular signaling network are interactions between billions of proteins and other biomolecules. These interactions, in turn, are greatly influenced by the spatial patterning of signaling and receptor molecules. The ability to observe signaling spatial patterns in the immune and other cellular systems as they evolve, and to study the impact on molecular interactions and, ultimately, cellular communication, would be a critical tool in the fight against immunological and other disorders that lead to a broad range of health problems including cancer. Such a tool is now at hand.

Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, have developed the first practical application of optical nanoantennas in cell membrane biology. A scientific team led by chemist Jay Groves has developed a technique for lacing artificial lipid membranes with billions of gold "bowtie" nanoantennas. Through the phenomenon known as "plasmonics," these nanoantennas can boost the intensity of a fluorescent or Raman optical signal from a protein passing through a plasmonic "hot-spot" tens of thousands of times without the protein ever being touched.

"Our technique is minimally invasive since enhancement of optical signals is achieved without requiring the molecules to directly interact with the nanoantenna," Groves says. "This is an important improvement over methods that rely on adsorption of molecules directly onto antennas where their structure, orientation, and behavior can all be altered."

Groves holds joint appointments with Berkeley Lab's Physical Biosciences Division and UC Berkeley's Chemistry Department, and is also a Howard Hughes Medical Institute investigator. He is the corresponding author of a paper that reports these results in the journal NanoLetters. The paper is titled "Single Molecule Tracking on Supported Membranes with Arrays of Optical Nanoantennas." Co-authoring the paper were Theo Lohmuller, Lars Iversen, Mark Schmidt, Christopher Rhodes, Hsiung-Lin Tu and Wan-Chen Lin.

Fluorescent emissions, in which biomolecules of interest are tagged with dyes that fluoresce when stimulated by light, and Raman spectroscopy, in which the scattering of light by molecular vibrations is used to identify and locate biomolecules, are work-horse optical imaging techniques whose value has been further enhanced by the emergence of plasmonics. In plasmonics, light waves are squeezed into areas with dimensions smaller than half-the-wavelength of the incident photons, making it possible to apply optical imaging techniques to nanoscale objects such as biomolecules. Nano-sized gold particles in the shape of triangles that are paired in a tip-to-tip formation, like a bow-tie, can serve as optical antennas, capturing and concentrating light waves into well-defined hot spots, where the plasmonic effect is greatly amplified. Although the concept is well-established, applying it to biomolecular studies has been a challenge because gold particle arrays must be fabricated with well-defined nanometer spacing, and molecules of interest must be delivered to plasmonic hot-spots.

"We're able to fabricate billions of gold nanoantennas in an artificial membrane through a combination of colloid lithography and plasma processing," Groves says. "Controlled spacing of the nanoantenna gaps is achieved by taking advantage of the fact that polystyrene particles melt together at their contact point during plasma processing. The result is well-defined spacing between each pair of gold triangles in the final array with a tip-to-tip distance between neighboring gold nanotriangles measuring in the 5-to-100 nanometer range."

Until now, Groves says, it has not been possible to decouple the size of the gold nanotriangles, which determines their surface plasmon resonance frequency, from the tip-to-tip distance between the individual nanoparticle features, which is responsible for enhancing the plasmonic effect. With their colloidal lithography approach, a self-assembling hexagonal monolayer of polymer spheres is used to shadow mask a substrate for subsequent deposition of the gold nanoparticles. When the colloidal mask is removed, what remains are large arrays of gold nanoparticles and triangles over which the artificial membrane can be formed.

The unique artificial membranes, which Groves and his research group developed earlier, are another key to the success of this latest achievement. Made from a fluid bilayer of lipid molecules, these membranes are the first biological platforms that can combine fixed nanopatterning with the mobility of fluid bilayers. They provide an unprecedented capability for the study of how the spatial patterns of chemical and physical properties on membrane surfaces influence the behavior of cells.

"When we embed our artificial membranes with gold nanoantennas we can trace the trajectories of freely diffusing individual proteins as they sequentially pass through and are enhanced by the multiple gaps between the triangles," Groves says. "This allows us to study a realistic system, like a cell, which can involve billions of molecules, without the static entrapment of the molecules."

As molecules in living cells are generally in a state of perpetual motion, it is often their movement and interactions with other molecules rather than static positions that determine their functions within the cell. Groves says that any technique requiring direct adsorption of a molecule of interest onto a nanoantenna intrinsically removes that molecule from the functioning ensemble that is the essence of its natural behavior. The technique he and his co-authors have developed allows them to look at individual biomolecules but within the context of their surrounding community.

"The idea that optical nanoantennas can produce the kinds of enhanced signals we are observing has been known for years but this is the first time that nanoantennas have been fabricated into a fluid membrane so that we can observe every molecule in the system as it passes through the antenna array," Groves says. "This is more than a proof-of-concept we've shown that we now have a useful new tool to add to our repertoire."

This research was primarily supported by the DOE Office of Science.

Laser Hints at How Universe Got Its Magnetism

2012-04-03T09:26:00.000-07:00

Scientists have used a laser to create magnetic fields similar to those thought to be involved in the formation of the first galaxies; findings that could help to solve the riddle of how the Universe got its magnetism.

Magnetic fields exist throughout galactic and intergalactic space, what is puzzling is how they were originally created and how they became so strong.

A team, led by Oxford University physicists, used a high-power laser to explode a rod of carbon, similar to pencil lead, in helium gas. The explosion was designed to mimic the cauldron of plasma -- an ionized gas containing free electrons and positive ions -- out of which the first galaxies formed.

The team found that within a microsecond of the explosion strong electron currents and magnetic fields formed around a shock wave. Astrophysicists took these results and scaled them through 22 orders-of-magnitude to find that their measurements matched the 'magnetic seeds' predicted by theoretical studies of galaxy formation.

A report of the research is published in a recent issue of the journal Nature.

'Our experiment recreates what was happening in the early Universe and shows how galactic magnetic fields might have first appeared,' said Dr Gianluca Gregori of Oxford University's Department of Physics, who led the work at Oxford. 'It opens up the exciting prospect that we will be able to explore the physics of the cosmos, stretching back billions of years, in a laser laboratory here on Earth.'

The results closely match theories which predict that tiny magnetic fields -- 'magnetic seeds' -- precede the formation of galaxies. These fields can be amplified by turbulent motions and can strongly affect the evolution of the galactic medium from its early stages.

Dr Gregori said: 'In the future, we plan to use the largest lasers in the world, such as the National Ignition Facility at the Lawrence Livermore National Laboratory in California (USA), to study the evolution of cosmic plasma.'

The experiments were conducted at the Laboratoire pour l'Utilisation de Lasers Intenses laser facility in France.

Materials Inspired by Mother Nature: One-Pound Boat That Could Float 1,000 Pounds

2012-04-02T09:25:00.000-07:00

Combining the secrets that enable water striders to walk on water and give wood its lightness and great strength has yielded an amazing new material so buoyant that, in everyday terms, a boat made from 1 pound of the substance could carry five kitchen refrigerators, about 1,000 pounds.

One of the lightest solid substances in the world, which is also sustainable, it was among the topics of a symposium in San Diego March 25 at the 243rd National Meeting & Exposition of the American Chemical Society, the world's largest scientific society. The symposium focused on an emerging field called biomimetics, in which scientists literally take inspiration from Mother Nature, probing and adapting biological systems in plants and animals for use in medicine, industry and other fields.

Olli Ikkala, Ph.D., described the new buoyant material, engineered to mimic the water strider's long, thin feet and made from an "aerogel" composed of the tiny nano-fibrils from the cellulose in plants. Aerogels are so light that some of them are denoted as "solid smoke." The nanocellulose aerogels also have remarkable mechanical properties and are flexible.

"These materials have really spectacular properties that could be used in practical ways," said Ikkala. He is with Helsinki University of Technology in Espoo, Finland. Potential applications range from cleaning up oil spills to helping create such products as sensors for detecting environmental pollution, miniaturized military robots, and even children's toys and super-buoyant beach floats.

Ikkala's presentation was among almost two dozen reports in the symposium titled, "Cellulose-Based Biomimetic and Biomedical Materials," that focused on the use of specially processed cellulose in the design and engineering of materials modeled after biological systems. Cellulose consists of long chains of the sugar glucose linked together into a polymer, a natural plastic-like material. Cellulose gives wood its remarkable strength and is the main component of plant stems, leaves and roots. Traditionally, cellulose's main commercial uses have been in producing paper and textiles -- cotton being a pure form of cellulose. But development of a highly processed form of cellulose, termed nanocellulose, has expanded those applications and sparked intense scientific research. Nanocellulose consists of the fibrils of nanoscale diameters so small that 50,000 would fit across the width of the period at the end of this sentence.

"We are in the middle of a Golden Age, in which a clearer understanding of the forms and functions of cellulose architectures in biological systems is promoting the evolution of advanced materials," said Harry Brumer, Ph.D., of Michael Smith Laboratories, University of British Columbia, Vancouver. He was a co-organizer of the symposium with J. Vincent Edwards, Ph.D., a research chemist with the Agricultural Research Service, U.S. Department of Agriculture in New Orleans, Louisiana. "This session on cellulose-based biomimetic and biomedical materials is really very timely due to the sustained and growing interest in the use of cellulose, particularly nanoscale cellulose, in biomaterials."

Ikkala pointed out that cellulose is the most abundant polymer on Earth, a renewable and sustainable raw material that could be used in many new ways. In addition, nanocellulose promises advanced structural materials similar to metals, such as high-tech spun fibers and films.

"It can be of great potential value in helping the world shift to materials that do not require petroleum for manufacture," Ikkala explained. "The use of wood-based cellulose does not influence the food supply or prices, like corn or other crops. We are really delighted to see how cellulose is moving beyond traditional applications, such as paper and textiles, and finding new high-tech applications."

One application was in Ikkala's so-called "nanocellulose carriers" that have such great buoyance. In developing the new material, Ikkala's team turned nanocellulose into an aerogel. Aerogels can be made from a variety of materials, even the silica in beach sand, and some are only a few times denser than air itself. By one estimate, if Michelangelo's famous statue David were made out of an aerogel rather than marble, it would be less than 5 pounds.

The team incorporated into the nanocellulose aerogel features that enable the water strider to walk on water. The material is not only highly buoyant, but is capable of absorbing huge amounts of oil, opening the way for potential use in cleaning up oil spills. The material would float on the surface, absorbing the oil without sinking. Clean-up workers, then, could retrieve it and recover the oil.

The American Chemical Society is a non-profit organization chartered by the U.S. Congress. With more than 164,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

Single Molecules in a Quantum Movie

2012-04-01T09:23:00.000-07:00

The quantum physics of massive particles has intrigued physicists for more than 80 years, since it predicts that even complex particles can exhibit wave-like behaviour -- in conflict with our everyday ideas of what is real or local. An international team of scientists now succeeded in shooting a movie which shows the build-up of a matter-wave interference pattern from single dye molecules which is so large (up to 0.1 mm) that you can easily see it with a camera. This visualizes the dualities of particle and wave, randomness and determinism, locality and delocalization in a particularly intuitive way.

A quantum premiere with dye molecules as leading actors

Physicist Richard Feynman once claimed that interference effects caused by matter-waves contain the only mystery of quantum physics. Understanding and applying matter waves for new technologies is also at the heart of the research pursued by the Quantum Nanophysics team around Markus Arndt at the University of Vienna and the Vienna Center for Quantum Science and Technology.

The scientists now premiered a movie which shows the build-up of a quantum interference pattern from stochastically arriving single phthalocyanine particles after these highly-fluorescent dye molecules traversed an ultra-thin nanograting. As soon as the molecules arrive on the screen the researchers take live images using a spatially resolving fluorescence microscope whose sensitivity is so high that each molecule can be imaged and located individually with an accuracy of about 10 nanometers. This is less than a thousandth of the diameter of a human hair and still less than 1/60 of the wavelength of the imaging light.

A breath of nothing

In these experiments van der Waals forces between the molecules and the gratings pose a particular challenge. These forces arise due to quantum fluctuations and strongly affect the observed interference pattern. In order to reduce the van der Waals interaction the scientists used gratings as thin as 10 nanometers (only about 50 silicon nitride layers). These ultra-thin gratings were manufactured by the nanotechnology team around Ori Cheshnovski at the Tel Aviv University who used a focused ion beam to cut the required slits into a free-standing membrane.

Tailored nanoparticles

In this study the experiments could be extended to phthalocyanine heavier derivatives which were tailor-made by Marcel Mayor and his group at the University of Basel. They represent the most massive molecules in quantum far-field diffraction so far.

Motivation and continuation

The newly developed and combined micro- and nanotechnologies for generating, diffracting and detecting molecular beams will be important for extending quantum interference experiments to more and more complex molecules but also for atom interferometry.

The experiments have a strongly didactical component: they reveal the single-particle character of complex quantum diffraction patterns on a macroscopic scale that is visible to the eye. You can see them emerge in real-time and they last for hours on the screen. The experiments thus render the wave-particle duality of quantum physics particularly tangible and conspicuous.

The experiments have a practical side, too. They allow to access molecular properties close to solid interfaces and they show a way towards future diffraction studies at atomically thin membranes.

Seeing is believing: the movie by Thomas Juffmann et al. is published on March 25 in Nature Nanotechnology. This project was supported by the Austrian FWF Z149-N16 (Wittgenstein), ESF/FWF/SNF MIME (I146) and the Swiss SNF in the NCCR "Nanoscale Science."

Can a Machine Tell When You're Lying? Research Suggests the Answer Is 'Yes'

2012-03-31T09:20:00.000-07:00

Inspired by the work of psychologists who study the human face for clues that someone is telling a high-stakes lie, UB computer scientists are exploring whether machines can also read the visual cues that give away deceit.

Results so far are promising: In a study of 40 videotaped conversations, an automated system that analyzed eye movements correctly identified whether interview subjects were lying or telling the truth 82.5 percent of the time.

That's a better accuracy rate than expert human interrogators typically achieve in lie-detection judgment experiments, said Ifeoma Nwogu, a research assistant professor at UB's Center for Unified Biometrics and Sensors (CUBS) who helped develop the system. In published results, even experienced interrogators average closer to 65 percent, Nwogu said.

"What we wanted to understand was whether there are signal changes emitted by people when they are lying, and can machines detect them? The answer was yes, and yes," said Nwogu, whose full name is pronounced "e-fo-ma nwo-gu."

The research was peer-reviewed, published and presented as part of the 2011 IEEE Conference on Automatic Face and Gesture Recognition.

Nwogu's colleagues on the study included CUBS scientists Nisha Bhaskaran and Venu Govindaraju, and UB communication professor Mark G. Frank, a behavioral scientist whose primary area of research has been facial expressions and deception.

In the past, Frank's attempts to automate deceit detection have used systems that analyze changes in body heat or examine a slew of involuntary facial expressions.

The automated UB system tracked a different trait -- eye movement. The system employed a statistical technique to model how people moved their eyes in two distinct situations: during regular conversation, and while fielding a question designed to prompt a lie.

People whose pattern of eye movements changed between the first and second scenario were assumed to be lying, while those who maintained consistent eye movement were assumed to be telling the truth. In other words, when the critical question was asked, a strong deviation from normal eye movement patterns suggested a lie.

Previous experiments in which human judges coded facial movements found documentable differences in eye contact at times when subjects told a high-stakes lie.

What Nwogu and fellow computer scientists did was create an automated system that could verify and improve upon information used by human coders to successfully classify liars and truth tellers. The next step will be to expand the number of subjects studied and develop automated systems that analyze body language in addition to eye contact.

Nwogu said that while the sample size was small, the findings are exciting.

They suggest that computers may be able to learn enough about a person's behavior in a short time to assist with a task that challenges even experienced interrogators. The videos used in the study showed people with various skin colors, head poses, lighting and obstructions such as glasses.

This does not mean machines are ready to replace human questioners, however -- only that computers can be a helpful tool in identifying liars, Nwogu said.

She noted that the technology is not foolproof: A very small percentage of subjects studied were excellent liars, maintaining their usual eye movement patterns as they lied. Also, the nature of an interrogation and interrogators' expertise can influence the effectiveness of the lie-detection method.

The videos used in the study were culled from a set of 132 that Frank recorded during a previous experiment.

In Frank's original study, 132 interview subjects were given the option to "steal" a check made out to a political party or cause they strongly opposed.

Subjects who took the check but lied about it successfully to a retired law enforcement interrogator received rewards for themselves and a group they supported; Subjects caught lying incurred a penalty: they and their group received no money, but the group they despised did. Subjects who did not steal the check faced similar punishment if judged lying, but received a smaller sum for being judged truthful.

The interrogators opened each interview by posing basic, everyday questions. Following this mundane conversation, the interrogators asked about the check. At this critical point, the monetary rewards and penalties increased the stakes of lying, creating an incentive to deceive and do it well.

In their study on automated deceit detection, Nwogu and her colleagues selected 40 videotaped interrogations.

They used the mundane beginning of each to establish what normal, baseline eye movement looked like for each subject, focusing on the rate of blinking and the frequency with which people shifted their direction of gaze.

The scientists then used their automated system to compare each subject's baseline eye movements with eye movements during the critical section of each interrogation -- the point at which interrogators stopped asking everyday questions and began inquiring about the check.

If the machine detected unusual variations from baseline eye movements at this time, the researchers predicted the subject was lying.

New 'Thermal' Approach to Invisibility Cloaking Hides Heat to Enhance Technology

2012-03-30T09:19:00.000-07:00

In a new approach to invisibility cloaking, a team of French researchers has proposed isolating or cloaking objects from sources of heat -- essentially "thermal cloaking." This method, which the researchers describe in the Optical Society's (OSA) open-access journal Optics Express, taps into some of the same principles as optical cloaking and may lead to novel ways to control heat in electronics and, on an even larger scale, might someday prove useful for spacecraft and solar technologies.

Recent advances in invisibility cloaks are based on the physics of transformation optics, which involves metamaterials and bending light so that it propagates around a space rather than through it. Sebastien Guenneau, affiliated with both the University of Aix-Marseille and France's Centre National de la Recherche Scientifique (CRNS), decided to investigate, with CRNS colleagues, whether a similar approach might be possible for thermal diffusion.

"Our key goal with this research was to control the way heat diffuses in a manner similar to those that have already been achieved for waves, such as light waves or sound waves, by using the tools of transformation optics," says Guenneau.

Though this technology uses the same fundamental theories as recent advances in optical cloaking, there is a key difference. Until now, he explains, cloaking research has revolved around manipulating trajectories of waves. These include electromagnetic (light), pressure (sound), elastodynamic (seismic), and hydrodynamic (ocean) waves. The biggest difference in their study of heat, he points out, is that the physical phenomenon involved is diffusion, not wave propagation.

"Heat isn't a wave -- it simply diffuses from hot to cold regions," Guenneau says. "The mathematics and physics at play are much different. For instance, a wave can travel long distances with little attenuation, whereas temperature usually diffuses over smaller distances."

To create their thermal invisibility cloak, Guenneau and colleagues applied the mathematics of transformation optics to equations for thermal diffusion and discovered that their idea could work.

In their two-dimensional approach, heat flows from a hot to a cool object with the magnitude of the heat flux through any region in space represented by the distance between isotherms (concentric rings of diffusivity). They then altered the geometry of the isotherms to make them go around rather than through a circular region to the right of the heat source -- so that any object placed in this region can be shielded from the flow of heat (see image).

"We can design a cloak so that heat diffuses around an invisibility region, which is then protected from heat. Or we can force heat to concentrate in a small volume, which will then heat up very rapidly," Guenneau says.

The ability to shield an area from heat or to concentrate it are highly desirable traits for a wide range of applications. Shielding nanoelectronic and microelectronic devices from overheating, for example, is one of the biggest challenges facing the electronics and semiconductor industries, and an area in which thermal cloaking could have a huge impact. On a larger scale and far into the future, large computers and spacecraft could also benefit greatly. And in terms of concentrating heat, this is a characteristic that the solar industry should find intriguing.

Guenneau and colleagues are now working to develop prototypes of their thermal cloaks for microelectronics, which they expect to have ready within the next few months.

Butterfly Wings' 'Art of Blackness' Could Boost Production of Green Fuels

2012-03-29T09:18:00.000-07:00

Butterfly wings may rank among the most delicate structures in nature, but they have given researchers powerful inspiration for new technology that doubles production of hydrogen gas -- a green fuel of the future -- from water and sunlight.

The researchers presented their findings in San Diego on March 26 at the American Chemical Society's (ACS') 243rd National Meeting & Exposition.

Tongxiang Fan, Ph.D., who reported on the use of two swallowtail butterflies -- Troides aeacus (Heng-chun birdwing butterfly) and Papilio helenus Linnaeus (Red Helen) -- as models, explained that finding renewable sources of energy is one of the great global challenges of the 21st century. One promising technology involves producing clean-burning hydrogen fuel from sunlight and water. It can be done in devices that use sunlight to kick up the activity of catalysts that split water into its components, hydrogen and oxygen. Better solar collectors are the key to making the technology practical, and Fan's team turned to butterfly wings in their search for making solar collectors that gather more useful light.

"We realized that the solution to this problem may have been in existence for millions of years, fluttering right in front of our eyes," Fan said. "And that was correct. Black butterfly wings turned out to be a natural solar collector worth studying and mimicking," Fan said.

Scientists long have known that butterfly wings contain tiny scales that serve as natural solar collectors to enable butterflies, which cannot generate enough heat from their own metabolism, to remain active in the cold. When butterflies spread their wings and bask in the sun, those solar collectors are soaking up sunlight and warming the butterfly's body.

Fan's team at Shanghai Jiao Tong University in China used an electron microscope to reveal the most-minute details of the scale architecture on the wings of black butterflies -- black being the color that absorbs the maximum amount of sunlight.

"We were searching the 'art of blackness' for the secret of how those black wings absorb so much sunlight and reflect so little," Fan explained.

Scientists initially thought it was simply a matter of the deep inky black color, due to the pigment called melanin, which also occurs in human skin. More recently, however, evidence began to emerge indicating that the structure of the scales on the wings should not be ignored.

Fan's team observed elongated rectangular scales arranged like overlapping shingles on the roof of a house. The butterflies they examined had slightly different scales, but both had ridges running the length of the scale with very small holes on either side that opened up onto an underlying layer.

The steep walls of the ridges help funnel light into the holes, Fan explained. The walls absorb longer wavelengths of light while allowing shorter wavelengths to reach a membrane below the scales. Using the images of the scales, the researchers created computer models to confirm this filtering effect. The nano-hole arrays change from wave guides for short wavelengths to barriers and absorbers for longer wavelengths, which act just like a high-pass filtering layer.

The group used actual butterfly-wing structures to collect sunlight, employing them as templates to synthesize solar-collecting materials. They chose the black wings of the Asian butterfly Papilio helenus Linnaeus, or Red Helen, and transformed them to titanium dioxide by a process known as dip-calcining. Titanium dioxide is used as a catalyst to split water molecules into hydrogen and oxygen. Fan's group paired this butterfly-wing patterned titanium dioxide with platinum nanoparticles to increase its water-splitting power. The butterfly-wing compound catalyst produced hydrogen gas from water at more than twice the rate of the unstructured compound catalyst on its own.

"These results demonstrate a new strategy for mimicking Mother Nature's elaborate creations in making materials for renewable energy. The concept of learning from nature could be extended broadly, and thus give a broad scope of building technologically unrealized hierarchical architecture and design blueprints to exploit solar energy for sustainable energy resources," he concluded.

The scientists acknowledged funding from National Natural Science Foundation of China (No.51172141 and 50972090), Shanghai Rising-star Program (No.10QH1401300).

Tiny Reader Makes Fast, Cheap DNA Sequencing Feasible

2012-03-28T09:16:00.000-07:00

Researchers have devised a nanoscale sensor to electronically read the sequence of a single DNA molecule, a technique that is fast and inexpensive and could make DNA sequencing widely available.

The technique could lead to affordable personalized medicine, potentially revealing predispositions for afflictions such as cancer, diabetes or addiction.

"There is a clear path to a workable, easily produced sequencing platform," said Jens Gundlach, a University of Washington physics professor who leads the research team. "We augmented a protein nanopore we developed for this purpose with a molecular motor that moves a DNA strand through the pore a nucleotide at a time."

The researchers previously reported creating the nanopore by genetically engineering a protein pore from a mycobacterium. The nanopore, from Mycobacterium smegmatis porin A, has an opening 1 billionth of a meter in size, just large enough for a single DNA strand to pass through.

To make it work as a reader, the nanopore was placed in a membrane surrounded by potassium-chloride solution, with a small voltage applied to create an ion current flowing through the nanopore. The electrical signature changes depending on the type of nucleotide traveling through the nanopore. Each type of DNA nucleotide -- cytosine, guanine, adenine and thymine -- produces a distinctive signature.

The researchers attached a molecular motor, taken from an enzyme associated with replication of a virus, to pull the DNA strand through the nanopore reader. The motor was first used in a similar effort by researchers at the University of California, Santa Cruz, but they used a different pore that could not distinguish the different nucleotide types.

Gundlach is the corresponding author of a paper published online March 25 by Nature Biotechnology that reports a successful demonstration of the new technique using six different strands of DNA. The results corresponded to the already known DNA sequence of the strands, which had readable regions 42 to 53 nucleotides long.

"The motor pulls the strand through the pore at a manageable speed of tens of milliseconds per nucleotide, which is slow enough to be able to read the current signal," Gundlach said.

Gundlach said the nanopore technique also can be used to identify how DNA is modified in a given individual. Such modifications, referred to as epigenetic DNA modifications, take place as chemical reactions within cells and are underlying causes of various conditions.

"Epigenetic modifications are rather important for things like cancer," he said. Being able to provide DNA sequencing that can identify epigenetic changes "is one of the charms of the nanopore sequencing method."

Coauthors of the Nature Biotechnology paper are Elizabeth Manrao, Ian Derrington, Andrew Laszlo, Kyle Langford, Matthew Hopper and Nathaniel Gillgren of the UW, and Mikhail Pavlenok and Michael Niederweis of the University of Alabama at Birmingham.

The work was funded by the National Human Genome Research Institute in a program designed to find a way to conduct individual DNA sequencing for less than $1,000. When that program began, Gundlach said, the cost of such sequencing was likely in the hundreds of thousands of dollars, but "with techniques like this it might get down to a 10-dollar or 15-minute genome project. It's moving fast."

Research: 'Buckliball' Opens New Avenue in Design of Foldable Engineering Structures

2012-03-27T09:15:00.000-07:00

Motivated by the desire to determine the simplest 3-D structure that could take advantage of mechanical instability to collapse reversibly, a group of engineers at MIT and Harvard University were stymied -- until one of them happened across a collapsible, spherical toy that resembled the structures they'd been exploring, but with a complex layout of 26 solid moving elements and 48 rotating hinges.

The toy inspired the engineers to create the "buckliball," a hollow, spherical object made of soft rubber containing no moving parts, but fashioned with 24 carefully spaced dimples. When the air is sucked out of a buckliball with a syringe, the thin ligaments forming columns between lateral dimples collapse. This is the engineering equivalent of applying equal load on all beams in a structure simultaneously to induce buckling, a phenomenon first studied by mathematician Leonhard Euler in 1757.

When the buckliball's thin ligaments buckle, the thicker ligaments forming rows between dimples undergo a series of movements the researchers refer to as a "cooperative buckling cascade." Some of the thick ligaments rotate clockwise, others counterclockwise -- but all move simultaneously and harmoniously, turning the original circular dimples into vertical and horizontal ellipses in alternating patterns before closing them entirely. As a result, the buckliball morphs into a rhombicuboctahedron about half the size (46 percent) of the original sphere.

The researchers named their new structure for its use of buckling and its resemblance to buckyballs, spherical all-carbon molecules whose name was inspired by the geodesic domes created by architect-inventor Buckminster Fuller. The buckliball is the first morphable structure to incorporate buckling as a desirable engineering design element. The buckling process induces folding in portions of the sphere -- similar to the way paper folds in origami -- so the researchers place their buckliball in a larger framework of buckling-induced origami they call "buckligami."

Because their collapse is fully reversible and can be achieved without moving parts, morphable structures such as the buckliball have the potential for widespread applications, from the micro- to macroscale. They could be used to create large buildings with collapsible roofs or walls, tiny drug-delivery capsules or soft movable joints requiring no mechanical pieces. They also have the potential to transform Transformers and other kinds of toys. (The toy that provided the researchers' epiphany is the Hoberman Twist-O.)

The researchers -- Jongmin Shim MS '05, PhD '10, a postdoc at Harvard; Claude Perdigo, a visiting graduate student at MIT; Elizabeth Chen, a recent graduate of the University of Michigan who will join Harvard as a postdoc in the fall; Katia Bertoldi, an assistant professor in applied mechanics at Harvard; and Pedro Reis, the Esther and Harold E. Edgerton Assistant Professor of Civil and Environmental Engineering and Mechanical Engineering at MIT -- wrote a paper about this work that appears this week in the Proceedings of the National Academy of Sciences.

"In civil engineering, buckling is commonly associated with failure that must be avoided. For example, one typically wants to calculate the buckling criterion for columns and apply an additional safety factor, to ensure that a building stands," Reis says. "We are trying to change this paradigm by turning failure into functionality in soft mechanical structures. For us, the buckliball is the first such object, but there will be many others." For instance, a robotic arm could be built from a single piece of material using a precisely engineered pattern of dimples at the intended hinging points that, when activated by a pressure signal, would bend.

"The buckliball not only opens avenues for the design of foldable structures over a wide range of length scales, but may also be used as a building block for creating new materials with unusual properties, capable of dramatic contraction in all directions," Bertoldi says.

Reis's research uses precision tabletop-scale lab tests and mathematical analysis to determine the basic physics underlying the mechanical behavior of materials. Bertoldi's research group uses tools from continuum and computational mechanics to unravel the mechanics of soft structures. The two teams collaborated on the buckliball: Reis' team performed the lab experiments with the help of digital fabrication techniques (such as 3-D printing) to create objects with precise geometry, and Bertoldi's group used computation to further analyze the detailed mechanics of the process.

Chen, who was visiting Harvard at the time, determined that only five spherical geometric structures have the potential for reversible buckling-induced collapse. (The specific example of Fuller's 12-hole rhombicuboctahedron that collapses into a cuboctahedron is one of these five.) Design parameters for buckliballs include dimple size, the thickness of the thin shell inside the dimple and the stiffness of the material used to fabricate the buckliball.

Nature, it appears, has already figured this out. Viruses inject their nucleic acids into a host through a reversible structural transformation in which 60 holes open or close based on changes in the acidity of the cell's environment, a different mechanism that achieves a similar reversible collapse at the nanoscale.

"What's exciting about this work is that it uses instabilities to basically amplify small or moderate pressures into dramatic motion," says Carmel Majidi, an assistant professor of mechanical engineering at Carnegie Mellon University whose research in soft robotics focuses on stretchable skin-like materials containing sensors. "One limitation of working with soft-material robotics is that they're soft; they can't produce the high pressures you get with heavy machines, so you're left with machines that provide only fairly moderate pressures. This makes it difficult to achieve dramatic deformations. If you use a robotic skin as an assistive medical device on a human, it can monitor motion. But with advancements like the buckliball, the skin may even be able to actively change its shape and directly help with motor tasks."

The work was funded through a National Science Foundation grant to the Harvard Materials Research Science and Engineering Center and by funds from Harvard University and MIT.

Astronomers Solve Mystery of Vanishing Electrons in Earth's Outer Radiation Belt

2012-02-24T21:41:00.000-08:00

UCLA researchers have explained the puzzling disappearing act of energetic electrons in Earth's outer radiation belt, using data collected from a fleet of orbiting spacecraft. (Credit: NASA Goddard Space Flight Center / Image by Reto Stöckli /Enhancements by Robert Simmon)

UCLA researchers have explained the puzzling disappearing act of energetic electrons in Earth's outer radiation belt, using data collected from a fleet of orbiting spacecraft.

In a paper published Jan. 29 in the advance online edition of the journalNature Physics, the team shows that the missing electrons are swept away from the planet by a tide of solar wind particles during periods of heightened solar activity.

"This is an important milestone in understanding Earth's space environment," said lead study author Drew Turner, an assistant researcher in the UCLA Department of Earth and Space Sciences and a member of UCLA's Institute for Geophysics and Planetary Physics (IGPP). "We are one step closer towards understanding and predicting space weather phenomena."

During powerful solar events such as coronal mass ejections, parts of the magnetized outer layers of sun's atmosphere crash onto Earth's magnetic field, triggering geomagnetic storms capable of damaging the electronics of orbiting spacecraft. These cosmic squalls have a peculiar effect on Earth's outer radiation belt, a doughnut-shaped region of space filled with electrons so energetic that they move at nearly the speed of light.

"During the onset of a geomagnetic storm, nearly all the electrons trapped within the radiation belt vanish, only to come back with a vengeance a few hours later," said Vassilis Angelopoulos, a UCLA professor of Earth and space sciences and IGPP researcher.

The missing electrons surprised scientists when the trend was first measured in the 1960s by instruments onboard the earliest spacecraft sent into orbit, said study co-author Yuri Shprits, a research geophysicist with the IGPP and the departments of Earth and space sciences, and atmospheric and oceanic sciences.

"It's a puzzling effect," he said. "Oceans on Earth do not suddenly lose most of their water, yet radiation belts filled with electrons can be rapidly depopulated."

Even stranger, the electrons go missing during the peak of a geomagnetic storm, a time when one might expect the radiation belt to be filled with energetic particles because of the extreme bombardment by the solar wind.

Where do the electrons go? This question has remained unresolved since the early 1960s. Some believed the electrons were lost to Earth's atmosphere, while others hypothesized that the electrons were not permanently lost at all but merely temporarily drained of energy so that they appeared absent.

"Our study in 2006 suggested that electrons may be, in fact, lost to the interplanetary medium and decelerated by moving outwards," Shprits said. "However, until recently, there was no definitive proof for this theory."

To resolve the mystery, Turner and his team used data from three networks of orbiting spacecraft positioned at different distances from Earth to catch the escaping electrons in the act. The data show that while a small amount of the missing energetic electrons did fall into the atmosphere, the vast majority were pushed away from the planet, stripped away from the radiation belt by the onslaught of solar wind particles during the heightened solar activity that generated the magnetic storm itself.

A greater understanding of Earth's radiation belts is vital for protecting the satellites we rely on for global positioning, communications and weather monitoring, Turner said. Earth's outer radiation belt is a harsh radiation environment for spacecraft and astronauts; the high-energy electrons can penetrate a spacecraft's shielding and wreak havoc on its delicate electronics. Geomagnetic storms triggered when the oncoming particles smash into Earth's magnetosphere can cause partial or total spacecraft failure.

"While most satellites are designed with some level of radiation protection in mind, spacecraft engineers must rely on approximations and statistics because they lack the data needed to model and predict the behavior of high-energy electrons in the outer radiation belt," Turner said.

During the 2003 "Halloween Storm," more than 30 satellites reported malfunctions, and one was a total loss, said Angelopoulos, a co-author of the current research. As the solar maximum approaches in 2013, marking the sun's peak activity over a roughly 11-year cycle, geomagnetic storms may occur as often as several times per month.

"High-energy electrons can cut down the lifetime of a spacecraft significantly," Turner said. "Satellites that spend a prolonged period within the active radiation belt might stop functioning years early."

While a mechanized spacecraft might include multiple redundant circuits to reduce the risk of total failure during a solar event, human explorers in orbit do not have the same luxury. High-energy electrons can punch through astronauts' spacesuits and pose serious health risks, Turner said.

"As a society, we've become incredibly dependent on space-based technology," he said. "Understanding this population of energetic electrons and their extreme variations will help create more accurate models to predict the effect of geomagnetic storms on the radiation belts."

Key observational data used in this study was collected by a network of NASA spacecraft known as THEMIS (Time History of Events and Macroscale Interactions during Substorms); Angelopoulos is the principal investigator of the THEMIS mission. Additional information was obtained from two groups of weather satellites called POES (Polar Operational Environmental Satellite) and GOES (Geostationary Operational Environmental Satellite).

A new collaboration between UCLA and Russia's Moscow State University promises to paint an even clearer picture of these vanishing electrons. Slated for launch in the spring of 2012, the Lomonosov spacecraft will fly in low Earth orbit to measure highly energetic particles with unprecedented accuracy, said Shprits, the principal investigator of the project. Several key instruments for the mission are being developed and assembled at UCLA.

Earth's radiation belts were discovered in 1958 by Explorer I, the first U.S. satellite that traveled to space.

"What we are studying was the first discovery of the space age," Shprits said. "People realized that launches of spacecraft didn't only make the news, they could also make scientific discoveries that were completely unexpected."

This project received federal funding from NASA and the National Science Foundation. Other co-authors include Michael Hartinger, a UCLA graduate student in Earth and space sciences.

Story Source:

The above story is reprinted from materials provided by University of California - Los Angeles. The original article was written by Kim DeRose.

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

Journal Reference:

Drew L. Turner, Yuri Shprits, Michael Hartinger, Vassilis Angelopoulos. Explaining sudden losses of outer radiation belt electrons during geomagnetic storms.Nature Physics, 2012; DOI: 10.1038/nphys2185

Kitchen Gadget Inspires Scientist to Make More Effective Plastic Electronics

2012-02-23T21:32:00.000-08:00

Fabricating single crystal organic field-effect transistors using ultra-thin polymer membrane for a gate insulator. In the upper row, the membrane is stretched over the transistor before vacuum is applied. In the lower row, the vacuum has been applied and the membrant is adhering to the organic crystal. Photos on the right are close-up views of the transistor, with the organic semiconductor crystal in red. (Credit: Credit: H. T. Yi, et. al.)

One day in 2010, Rutgers physicist Vitaly Podzorov watched a store employee showcase a kitchen gadget that vacuum-seals food in plastic. The demo stuck with him. The simple concept -- an airtight seal around pieces of food -- just might apply to his research: developing flexible electronics using lightweight organic semiconductors for products such as video displays or solar cells.

"Organic transistors, which switch or amplify electronic signals, hold promise for making video displays that bend like book pages or roll and unroll like posters," said Podzorov. But traditional methods of fabricating a part of the transistor known as the gate insulator often end up damaging the transistor's delicate semiconductor crystals.

Drawing inspiration from the food-storage gadget, Podzorov and his colleagues tried an experiment. They suspended a thin polymer membrane above the organic crystal and created a vacuum underneath, causing the membrane to collapse gently and evenly onto the crystal's surface. The result: a smooth, defect-free interface between the organic semiconductor and the gate insulator.

The researchers reported their success in the journal Advanced Materials. In the article,Podzorov and three colleagues describe how a single-crystal organic field effect transistor (OFET) made with this thin polymer gate insulator boosted electrical performance. The researchers further reported that they could remove and reapply membranes to the same crystal several times without degrading its surface.

Organic transistors electrically resemble silicon transistors in computer chips, but they are made of flexible carbon-based molecules that can be printed on sheets of plastic. Silicon transistors are made in rigid, brittle wafers of silicon.

The methods that scientists previously applied to organic transistor fabrication were based on silicon semiconductor processing, explained Podzorov, assistant professor in the Department of Physics and Astronomy, School of Arts and Sciences. These involved high temperatures, high-energy plasmas or chemical reactions, all of which could damage the delicate organic crystal surface and hinder the transistor's performance.

"People have tendencies to go with something they've known for a long time," he said. "In this case, it doesn't work right."

Podzorov's innovation builds upon a decade of Rutgers research in this field, including his invention of the first single crystal organic transistor in 2003. While his latest innovation is still a ways from commercial reality, he sees an immediate application in the classroom.

"Our technique takes 10 minutes," he said. "It should be exciting for students to actually build these devices and immediately see them work, all within one lab session."

Podzorov was actually trying to solve another problem when he first recalled the food packaging demo. He was thinking about how to protect organic crystals from airborne impurities when his lab shipped samples to collaborating scientists in California and overseas.

"We could place our samples between plastic sheets and pull a vacuum," he said. "Then I thought, 'why don't we try doing this for our gate insulator?'"

Funding for the research was provided by the U. S. Department of Energy and the Rutgers Institute for Advanced Materials and Devices for Nanotechnology. Collaborators in Podzorov's lab were postdoctoral researchers Hee Taek Yi and Yuanzhen Chen, and undergraduate student Krzysztof Czelen. The department's machine shop made a custom-designed vacuum chamber for the project

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Journal Reference:

H. T. Yi, Y. Chen, K. Czelen, V. Podzorov. Vacuum Lamination Approach to Fabrication of High-Performance Single-Crystal Organic Field-Effect Transistors. Advanced Materials, 2011; 23 (48): 5807 DOI:10.1002/adma.201103305

Microbubbles Provide New Boost for Biofuel Production

2012-02-22T21:28:00.000-08:00

A solution to the difficult issue of harvesting algae for use as a biofuel has been developed using microbubble technology pioneered at the University of Sheffield. The technique builds on previous research in which microbubbles were used to improve the way algae is cultivated.

Algae produce an oil which can be processed to create a useful biofuel. Biofuels, made from plant material, are considered an important alternative to fossil fuels and algae, in particular, has the potential to be a very efficient biofuel producer. Until now, however, there has been no cost-effective crmethod of harvesting and removing the water from the algae for it to be processed effectively.

Now, a team led by Professor Will Zimmerman in the Department of Chemical and Biological Engineering at the University of Sheffield, believe they have solved the problem. They have developed an inexpensive way of producing microbubbles that can float algae particles to the surface of the water, making harvesting easier, and saving biofuel-producing companies time and money.

The research is set to be published in Biotechnology and Bioengineering on 26 January 2012.

Professor Zimmerman and his team won the Moulton Medal, from the Institute of Chemical Engineers, for their earlier work which used the microbubble technology to improve algae production methods, allowing producers to grow crops more rapidly and more densely.

"We thought we had solved the major barrier to biofuel companies processing algae to use as fuel when we used microbubbles to grow the algae more densely," explains Professor Zimmerman.

"It turned out, however, that algae biofuels still couldn´t be produced economically, because of the difficulty in harvesting and dewatering the algae. We had to develop a solution to this problem and once again, microbubbles provided a solution."

Microbubbles have been used for flotation before: water purification companies use the process to float out impurities, but it hasn´t been done in this context, partly because previous methods have been very expensive.

The system developed by Professor Zimmerman´s team uses up to 1000 times less energy to produce the microbubbles and, in addition, the cost of installing the Sheffield microbubble system is predicted to be much less than existing flotation systems.

The next step in the project is to develop a pilot plant to test the system at an industrial scale. Professor Zimmerman is already working with Tata Steel at their site in Scunthorpe using CO2 from their flue-gas stacks and plans to continue this partnership to test the new system.

Dr. Bruce Adderley, Manager Climate Change Breakthrough Technology, said, "Professor Zimmerman´s microbubble-based technologies are exactly the kind of step-change innovations that we are seeking as a means to address our emissions in the longer term, and we are delighted to have the opportunity to extend our relationship with Will and his team in the next phase of this pioneering research."

The research was supported by the University of Sheffield´s Knowledge Transfer Account, funded by the Engineering and Physical Sciences Research Council. It was also supported by the Royal Society Innovation Award 2010, and the Concept Fund of Yorkshire Forward

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Journal Reference:

James Hanotu, HC Hemaka Bandulasena, William B Zimmerman. Microflotation performance for algal separation. Biotechnology and Bioengineering, 2012; DOI:10.1002/bit.24449

Graphene Supermaterial Goes Superpermeable: Can Be Used to Distill Alcohol

2012-02-21T21:18:00.000-08:00

Dr Nair with the membrane. (Credit: Image courtesy of Manchester University)

Wonder material graphene has revealed another of its extraordinary properties -- University of Manchester researchers have found that it is superpermeable with respect to water.

Graphene is one of the wonders of the science world, with the potential to create foldaway mobile phones, wallpaper-thin lighting panels and the next generation of aircraft. The new finding at the University of Manchester gives graphene's potential a most surprising dimension -- graphene can also be used for distilling alcohol.

In a report published in Science, a team led by Professor Sir Andre Geim shows that graphene-based membranes are impermeable to all gases and liquids (vacuum-tight). However, water evaporates through them as quickly as if the membranes were not there at all.

This newly-found property can now be added to the already long list of superlatives describing graphene. It is the thinnest known material in the universe and the strongest ever measured. It conducts electricity and heat better than any other material. It is the stiffest one too and, at the same time, it is the most ductile. Demonstrating its remarkable properties won University of Manchester academics the Nobel Prize in Physics in 2010.

Now the University of Manchester scientists have studied membranes from a chemical derivative of graphene called graphene oxide. Graphene oxide is the same graphene sheet but it is randomly covered with other molecules such as hydroxyl groups OH-. Graphene oxide sheets stack on top of each other and form a laminate.

The researchers prepared such laminates that were hundreds times thinner than a human hair but remained strong, flexible and were easy to handle.

When a metal container was sealed with such a film, even the most sensitive equipment was unable to detect air or any other gas, including helium, to leak through.

It came as a complete surprise that, when the researchers tried the same with ordinary water, they found that it evaporates without noticing the graphene seal. Water molecules diffused through the graphene-oxide membranes with such a great speed that the evaporation rate was the same independently whether the container was sealed or completely open.

Dr Rahul Nair, who was leading the experimental work, offers the following explanation: "Graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules. They arrange themselves in one molecule thick sheets of ice which slide along the graphene surface with practically no friction.

"If another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules."

"Helium gas is hard to stop. It slowly leaks even through a millimetre -thick window glass but our ultra-thin films completely block it. At the same time, water evaporates through them unimpeded. Materials cannot behave any stranger," comments Professor Geim. "You cannot help wondering what else graphene has in store for us."

"This unique property can be used in situations where one needs to remove water from a mixture or a container, while keeping in all the other ingredients," says Dr Irina Grigorieva who also participated in the research.

"Just for a laugh, we sealed a bottle of vodka with our membranes and found that the distilled solution became stronger and stronger with time. Neither of us drinks vodka but it was great fun to do the experiment," adds Dr Nair.

The Manchester researchers report this experiment in theirScience paper, too, but they say they do not envisage use of graphene in distilleries, nor offer any immediate ideas for applications.

However, Professor Geim adds 'The properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes and for selective removal of water'.

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The above story is reprinted from materials provided byManchester University, via AlphaGalileo.

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Journal Reference:

R. R. Nair, H. A. Wu, P. N. Jayaram, I. V. Grigorieva, A. K. Geim. Unimpeded Permeation of Water Through Helium-Leak-Tight Graphene-Based Membranes.Science, 2012; 335 (6067): 442 DOI:10.1126/science.1211694

How Seawater Could Corrode Nuclear Fuel

2012-02-20T10:00:00.000-08:00

Japan used seawater to cool nuclear fuel at the stricken Fukushima-Daiichi nuclear plant after the tsunami in March 2011 -- and that was probably the best action to take at the time, says Professor Alexandra Navrotsky of the University of California, Davis.

But Navrotsky and others have since discovered a new way in which seawater can corrode nuclear fuel, forming uranium compounds that could potentially travel long distances, either in solution or as very small particles. The research team published its work Jan. 23 in the Proceedings of the National Academy of Sciences.

"This is a phenomenon that has not been considered before," said Alexandra Navrotsky, distinguished professor of ceramic, earth and environmental materials chemistry. "We don't know how much this will increase the rate of corrosion, but it is something that will have to be considered in future."

Japan used seawater to avoid a much more serious accident at the Fukushima-Daiichi plant, and Navrotsky said, to her knowledge, there is no evidence of long-distance uranium contamination from the plant.

Uranium in nuclear fuel rods is in a chemical form that is "pretty insoluble" in water, Navrotsky said, unless the uranium is oxidized to uranium-VI -- a process that can be facilitated when radiation converts water into peroxide, a powerful oxidizing agent.

Peter Burns, professor of civil engineering and geological sciences at the University of Notre Dame and a co-author of the new paper, had previously made spherical uranium peroxide clusters, rather like carbon "buckyballs," that can dissolve or exist as solids.

In the new paper, the researchers show that in the presence of alkali metal ions such as sodium -- for example, in seawater -- these clusters are stable enough to persist in solution or as small particles even when the oxidizing agent is removed.

In other words, these clusters could form on the surface of a fuel rod exposed to seawater and then be transported away, surviving in the environment for months or years before reverting to more common forms of uranium, without peroxide, and settling to the bottom of the ocean. There is no data yet on how fast these uranium peroxide clusters will break down in the environment, Navrotsky said.

Navrotsky and Burns worked with the following co-authors: postdoctoral researcher Christopher Armstrong and project scientist Tatiana Shvareva, UC Davis; May Nyman, Sandia National Laboratory, Albuquerque, N.M.; and Ginger Sigmon, University of Notre Dame. The U.S. Department of Energy supported the project.

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Journal Reference:

C. R. Armstrong, M. Nyman, T. Shvareva, G. E. Sigmon, P. C. Burns, A. Navrotsky. Uranyl peroxide enhanced nuclear fuel corrosion in seawater. Proceedings of the National Academy of Sciences, 2012; DOI:10.1073/pnas.1119758109

Rap Music Powers Rhythmic Action of Medical Sensor

2012-02-19T21:07:00.000-08:00

This graphic illustrates the principles behind the operation of a new type of miniature medical sensor powered by acoustic waves, including those found in music such as rap, blues, jazz and rock. The device, a pressure sensor, might ultimately help to treat people stricken with aneurisms or incontinence due to paralysis. (Credit: Birck Nanotechnology Center, Purdue University)

The driving bass rhythm of rap music can be harnessed to power a new type of miniature medical sensor designed to be implanted in the body.

Acoustic waves from music, particularly rap, were found to effectively recharge the pressure sensor. Such a device might ultimately help to treat people stricken with aneurysms or incontinence due to paralysis.

The heart of the sensor is a vibrating cantilever, a thin beam attached at one end like a miniature diving board. Music within a certain range of frequencies, from 200-500 hertz, causes the cantilever to vibrate, generating electricity and storing a charge in a capacitor, said Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering.

"The music reaches the correct frequency only at certain times, for example, when there is a strong bass component," he said. "The acoustic energy from the music can pass through body tissue, causing the cantilever to vibrate."

When the frequency falls outside of the proper range, the cantilever stops vibrating, automatically sending the electrical charge to the sensor, which takes a pressure reading and transmits data as radio signals. Because the frequency is continually changing according to the rhythm of a musical composition, the sensor can be induced to repeatedly alternate intervals of storing charge and transmitting data.

"You would only need to do this for a couple of minutes every hour or so to monitor either blood pressure or pressure of urine in the bladder," Ziaie said. "It doesn't take long to do the measurement."

Findings are detailed in a paper to be presented during the IEEE MEMS conference, which will be Jan. 29 to Feb. 2 in Paris. The paper was written by doctoral student Albert Kim, research scientist Teimour Maleki and Ziaie.

"This paper demonstrates the feasibility of the concept," he said.

The device is an example of a microelectromechanical system, or MEMS, and was created in the Birck Nanotechnology Center at the university's Discovery Park. The cantilever beam is made from a ceramic material called lead zirconate titanate, or PZT, which is piezoelectric, meaning it generates electricity when compressed. The sensor is about 2 centimeters long. Researchers tested the device in a water-filled balloon.

A receiver that picks up the data from the sensor could be placed several inches from the patient. Playing tones within a certain frequency range also can be used instead of music.

"But a plain tone is a very annoying sound," Ziaie said. "We thought it would be novel and also more aesthetically pleasing to use music."

Researchers experimented with four types of music: rap, blues, jazz and rock.

"Rap is the best because it contains a lot of low frequency sound, notably the bass," Ziaie said.

The sensor is capable of monitoring pressure in the urinary bladder and in the sack of a blood vessel damaged by an aneurism. Such a technology could be used in a system for treating incontinence in people with paralysis by checking bladder pressure and stimulating the spinal cord to close the sphincter that controls urine flow from the bladder. More immediately, it could be used to diagnose incontinence. The conventional diagnostic method now is to insert a probe with a catheter, which must be in place for several hours while the patient remains at the hospital.

"A wireless implantable device could be inserted and left in place, allowing the patient to go home while the pressure is monitored," Ziaie said.

The new technology offers potential benefits over conventional implantable devices, which either use batteries or receive power through a property called inductance, which uses coils on the device and an external transmitter. Both approaches have downsides. Batteries have to be replaced periodically, and data are difficult to retrieve from devices that use inductance; coils on the implanted device and an external receiver must be lined up precisely, and they can only be about a centimeter apart.

A patent application has been filed for the design.

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The above story is reprinted from materials provided by Purdue University. The original article was written by Emil Venere.

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NASA's Kepler Announces 11 New Planetary Systems Hosting 26 Planets

2012-02-17T21:03:00.000-08:00

This artist's concept shows an overhead view of the orbital position of the planets in systems with multiple transiting planets discovered by NASA's Kepler mission. All the colored planets have been verified. More vivid colors indicate planets that have been confirmed by their gravitational interactions with each other or the star. Several of these systems contain additional planet candidates (shown in grey) that have not yet been verified. (Credit: NASA Ames/UC Santa Cruz)

NASA's Kepler mission has discovered 11 new planetary systems hosting 26 confirmed planets. These discoveries nearly double the number of verified Kepler planets and triple the number of stars known to have more than one planet that transits, or passes in front of, the star. Such systems will help astronomers better understand how planets form.

The planets orbit close to their host stars and range in size from 1.5 times the radius of Earth to larger than Jupiter. Fifteen are between Earth and Neptune in size. Further observations will be required to determine which are rocky like Earth and which have thick gaseous atmospheres like Neptune. The planets orbit their host star once every six to 143 days. All are closer to their host star than Venus is to our sun.

"Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky," said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits."

Kepler identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars to detect when a planet passes in front of the star. That passage casts a small shadow toward Earth and the Kepler spacecraft.

"Confirming that the small decrease in the star's brightness is due to a planet requires additional observations and time-consuming analysis," said Eric Ford, associate professor of astronomy at the University of Florida and lead author of the paper confirming Kepler-23 and Kepler-24. "We verified these planets using new techniques that dramatically accelerated their discovery."

Each of the newly confirmed planetary systems contains two to five closely spaced transiting planets. In tightly packed planetary systems, the gravitational pull of the planets on each other causes some planets to accelerate and some to decelerate along their orbits. The acceleration causes the orbital period of each planet to change. Kepler detects this effect by measuring the changes, or so-called Transit Timing Variations.

Planetary systems with Transit Timing Variations can be verified without requiring extensive ground-based observations, accelerating confirmation of planet candidates. This detection technique also increases Kepler's ability to confirm planetary systems around fainter and more distant stars.

"By precisely timing when each planet transits its star, Kepler detected the gravitational tug of the planets on each other, clinching the case for 10 of the newly announced planetary systems," said Dan Fabrycky, Hubble Fellow at the University of California, Santa Cruz, and lead author for a paper confirming Kepler-29, 30, 31 and 32.

Five of the systems (Kepler-25, Kepler-27, Kepler-30, Kepler-31 and Kepler-33) contain a pair of planets where the inner planet orbits the star twice during each orbit of the outer planet. Four of the systems (Kepler-23, Kepler-24, Kepler-28 and Kepler-32) contain a pairing where the outer planet circles the star twice for every three times the inner planet orbits its star.

"These configurations help to amplify the gravitational interactions between the planets, similar to how my sons kick their legs on a swing at the right time to go higher," said Jason Steffen, the Brinson postdoctoral fellow at Fermilab Center for Particle Astrophysics in Batavia, Ill., and lead author of a paper confirming Kepler-25, 26, 27 and 28.

Kepler-33, a star that is older and more massive than our sun, had the most planets. The system hosts five planets, ranging in size from 1.5 to 5 times that of Earth. All of the planets are located closer to their star than any planet is to our sun.

The properties of a star provide clues for planet detection. The decrease in the star's brightness and duration of a planet transit combined with the properties of its host star present a recognizable signature. When astronomers detect planet candidates that exhibit similar signatures around the same star, the likelihood of any of these planet candidates being a false positive is very low.

"The approach used to verify the Kepler-33 planets shows the overall reliability is quite high," said Jack Lissauer, planetary scientist at NASA Ames Research Center at Moffett Field, Calif., and lead author of the paper on Kepler-33. "This is a validation by multiplicity."

These discoveries are published in four different papers in the Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.

Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., managed the Kepler mission's development.

Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters in Washington.

For more information about the Kepler mission and to view the digital press kit, visit http://www.nasa.gov/kepler . More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov

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Scorpions Inspire Scientists in Making Tougher Surfaces for Machinery

2012-02-11T10:00:00.000-08:00

Taking inspiration from the yellow fattail scorpion, which uses a bionic shield to protect itself against scratches from desert sandstorms, scientists have developed a new way to protect the moving parts of machinery from wear and tear.

A report on the research appears in ACS' journal Langmuir.

Zhiwu Han, Junqiu Zhang, Wen Li and colleagues explain that "solid particle erosion" is one of the important reasons for material damage or equipment failure. It causes millions of dollars of damage each year to helicopter rotors, rocket motor nozzles, turbine blades, pipes and other mechanical parts. The damage occurs when particles of dirt, grit and other hard material in the air, water or other fluids strike the surfaces of those parts. Filters can help remove the particles but must be replaced or cleaned, while harder, erosion-resistant materials cost more to develop and make. In an effort to develop better erosion-resistant surfaces, Han and Li's group sought the secrets of the yellow fattail scorpion for the first time. The scorpion evolved to survive the abrasive power of harsh sandstorms.

They studied the bumps and grooves on the scorpions' backs, scanning the creatures with a 3-D laser device and developing a computer program that modeled the flow of sand-laden air over the scorpions. The team used the model in computer simulations to develop actual patterned surfaces to test which patterns perform best. At the same time, the erosion tests were conducted in the simple erosion wind tunnel for groove surface bionic samples at various impact conditions. Their results showed that a series of small grooves at a 30-degree angle to the flowing gas or liquid give steel surfaces the best protection from erosion.

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Journal Reference:

Han Zhiwu, Zhang Junqiu, Ge Chao, Wen Li, Luquan Ren.Erosion Resistance of Bionic Functional Surfaces Inspired from Desert Scorpions. Langmuir, 2012; 120120101148000 DOI: 10.1021/la203942r

World's Most Powerful X-Ray Laser Creates 2-Million-Degree Matter

2012-02-10T10:00:00.000-08:00

This photograph shows the interior of a Linac Coherent Light Source SXR experimental chamber, set up for an investigation to create and measure a form of extreme, 2-million-degree matter known as “hot, dense matter.” The central part of the frame contains the holder for the material that will be converted by the powerful LCLS laser into hot, dense matter. To the left is an XUV spectrometer and to the right is a small red laser set up for alignment and positioning. (Credit: Photo courtesy of University of Oxford/Sam Vinko)

Researchers working at the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory have used the world's most powerful X-ray laser to create and probe a 2-million-degree piece of matter in a controlled way for the first time. This feat, reported inNature, takes scientists a significant step forward in understanding the most extreme matter found in the hearts of stars and giant planets, and could help experiments aimed at recreating the nuclear fusion process that powers the sun.

The experiments were carried out at SLAC's Linac Coherent Light Source (LCLS), whose rapid-fire laser pulses are a billion times brighter than those of any X-ray source before it. Scientists used those pulses to flash-heat a tiny piece of aluminum foil, creating what is known as "hot dense matter," and took the temperature of this solid plasma -- about 2 million degrees Celsius. The whole process took less than a trillionth of a second.

"The LCLS X-ray laser is a truly remarkable machine," said Sam Vinko, a postdoctoral researcher at Oxford University and the paper's lead author. "Making extremely hot, dense matter is important scientifically if we are ultimately to understand the conditions that exist inside stars and at the center of giant planets within our own solar system and beyond."

Scientists have long been able to create plasma from gases and study it with conventional lasers, said co-author Bob Nagler of SLAC, an LCLS instrument scientist. But no tools were available for doing the same at solid densities that cannot be penetrated by conventional laser beams.

"The LCLS, with its ultra-short wavelengths of X-ray laser light, is the first that can penetrate a dense solid and create a uniform patch of plasma -- in this case a cube one-thousandth of a centimeter on a side -- and probe it at the same time," Nagler said.

The resulting measurements, he said, will feed back into theories and computer simulations of how hot, dense matter behaves. This could help scientists analyze and recreate the nuclear fusion process that powers the sun.

"Those 60 hours when we first aimed the LCLS at a solid were the most exciting 60 hours of my entire scientific career," said Justin Wark, leader of the Oxford group. "LCLS is really going to revolutionize the field, in my view."

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The above story is reprinted from materials provided byDOE/SLAC National Accelerator Laboratory.

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Journal Reference:

S. M. Vinko, O. Ciricosta, B. I. Cho, K. Engelhorn, H.-K. Chung, C. R. D. Brown, T. Burian, J. Chalupský, R. W. Falcone, C. Graves, V. Hájková, A. Higginbotham, L. Juha, J. Krzywinski, H. J. Lee, M. Messerschmidt, C. D. Murphy, Y. Ping, A. Scherz, W. Schlotter, S. Toleikis, J. J. Turner, L. Vysin, T. Wang, B. Wu, U. Zastrau, D. Zhu, R. W. Lee, P. A. Heimann, B. Nagler, J. S. Wark. Creation and diagnosis of a solid-density plasma with an X-ray free-electron laser. Nature, 2012; DOI: 10.1038/nature10746