August 20, 2008, 6:32 PM CT

Creating unconventional metals

The semiconductor silicon and the ferromagnet iron are the basis for much of mankind's technology, used in everything from computers to electric motors. In this week's issue of the journal Nature (August 21st) an international group of scientists, including academic and industrial scientists from the UK, USA and Lesotho, report that they have combined these elements with a small amount of another common metal, manganese, to create a new material which is neither a magnet nor an ordinary semiconductor. The paper goes on to show how a small magnetic field can be used to switch ordinary semiconducting behaviour (such as that seen in the electronic-grade silicon which is used to make transistors) back on.

The new material exists in a quantum halfway house between magnet and semiconductor - in the same way that much more complex materials such as ceramics which exhibit high temperature superconductivity exist in quantum halfway houses between metals and magnetic insulators. The research is of fundamental importance because it demonstrates, for the first time, a simple recipe for reaching this halfway house, whilst also suggesting new mechanisms for controlling electrical currents and magnetism in semiconductor devices.

Professor J.F. DiTusa of Louisiana State University and a co-author of the paper said: "It's amazing that something which was thought to exist theoretically in mathematical physics could actually be found in an alloy which was simply formed by melting together a few common elements"......... Posted by: Sarah      Read more         Source

August 20, 2008, 1:34 AM CT

Controlling the behavior of quantum dots

Scientists from the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (JQI), a collaborative center of the University of Maryland and NIST, have reported a new way to fine-tune the light coming from quantum dots by manipulating them with pairs of lasers. Their technique, published in Physical Review Letters,* could significantly improve quantum dots as a source of pairs of entangled photons, a property with important applications in quantum information technologies. The accomplishment could accelerate development of powerful advanced cryptography applications, projected to be a key 21st-century technology.

Entangled photons are a peculiar consequence of quantum mechanics. Tricky to generate, they remain interconnected even when separated by large distances. Merely observing one instantaneously affects the properties of the other. The entanglement can be used in quantum communication to pass an encryption key that is by its nature completely secure, as any attempt to eavesdrop or intercept the key would be instantly detected. One goal of the NIST-JQI team is to develop quantum dots as a convenient source of entangled photons.

Quantum dots are nanoscale regions of a semiconductor material similar to the material in computer processors but with special properties due to their tiny dimensions. Though they can be composed of tens of thousands of atoms, quantum dots in a number of ways behave almost as if they were single atoms. Unfortunately, almost is not good enough when it comes to the fragile world of quantum cryptography and next-generation information technologies. When energized, a quantum dot emits photons, or particles of light, just as a solitary atom does. But imperfections in the shape of a quantum dot cause what should be overlapping energy levels to separate. This ruins the delicate balance of the ideal state mandatory to emit entangled photons......... Posted by: Kevin      Read more         Source

July 17, 2008, 9:23 PM CT

"Nanosculpture" Could Enable New Types of Heat Pumps

A new technique for growing single-crystal nanorods and controlling their shape using biomolecules could enable the development of smaller, more powerful heat pumps and devices that harvest electricity from heat.

Scientists at Rensselaer Polytechnic Institute have discovered how to direct the growth of nanorods made up of two single crystals using a biomolecular surfactant. The scientists were also able to create "branched" structures by carefully controlling the temperature, time, and amount of surfactant used during synthesis.

"Our work is the first to demonstrate the synthesis of composite nanorods with branching, wherein each nanorod consists of two materials - a single-crystal bismuth telluride nanorod core encased in a hollow cylindrical shell of single-crystal bismuth sulfide," said G. Ramanath, professor of materials science and engineering at Rensselaer and director of the university's Center for Future Energy Systems, who led the research project. "Branching and core-shell architectures have been independently demonstrated, but this is the first time that both features have been simultaneously realized through the use of a biomolecular surfactant".

Most nanostructures comprised of a core and a shell generally require more than one step to synthesize, but these new research results demonstrate how to synthesize such nanorods in only one step......... Posted by: Kevin      Read more         Source

July 15, 2008, 9:36 PM CT

For toy-like NASA robots in Arctic, ice research is child's play

Several snowmobiles navigated speedily over arctic ice and snow in Alaska's outback in late June. This scene might seem ordinary except that the recently unveiled snowmobiles are unmanned, autonomous, toy-size robots called SnoMotes the first prototype network of their kind envisioned to rove treacherous areas of the Arctic and Antarctic capturing more accurate measurements that will help researchers better understand what is causing the well-documented melting of ice in those regions.

Ayanna Howard, an associate professor in the School of Electrical and Computer Engineering at the Georgia Institute of Technology in Atlanta, worked with researchers at Pennsylvania State University in State College, Pa., to create the toy-like robots. The robots are designed to traverse terrain often too dangerous for scientists, in pursuit of barometric pressure, temperature, and relative humidity measurements that will help researchers improve climate models. Howard, a former member of NASA's Mars technology program team who developed SmartNav, an autonomous, next-generation Mars rover, believed that science-driven robotics could be just as useful of a vehicle to new discoveries on Earth as it has been in the quest to learn more about Mars.

"After working with robots for the Mars technology program, I thought a similar type of rover could be used to collect multiple science measurements on this planet," said Howard. She is lead on the SnoMotes project funded by the Advanced Information Systems Technology program in NASA's Earth Science Technology Office, a NASA Headquarters office located at Goddard Space Flight Center in Greenbelt, Md......... Posted by: Kevin      Read more         Source

July 14, 2008, 4:42 PM CT

Physicists tweak quantum force

Cymbals don't clash of their own accord - in our world, anyway.

But the quantum world is bizarrely different. Two metal plates, placed almost infinitesimally close together, spontaneously attract each other.

What seems like magic is known as the Casimir force, and it has been well-documented in experiments. The cause goes to the heart of quantum physics: Seemingly empty space is not actually empty but contains virtual particles linked to fluctuating electromagnetic fields. These particles push the plates from both the inside and the outside. However, only virtual particles of shorter wavelengths - in the quantum world, particles exist simultaneously as waves - can fit into the space between the plates, so that the outward pressure is slightly smaller than the inward pressure. The result is the plates are forced together.

Now, University of Florida physicists have found they can reduce the Casimir force by altering the surface of the plates. The discovery could prove useful as tiny "microelectromechanical" systems - so-called MEMS devices that are already used in a wide array of consumer products - become so small they are affected by quantum forces.

"We are not talking about an immediate application," says Ho Bun Chan, an assistant professor of physics and the first author of a paper on the findings that appears today in the online edition of the journal Physical Review Letters......... Posted by: Kevin      Read more         Source

July 10, 2008, 8:26 PM CT

A Colorful Approach to Solar Energy

Revisiting a once-abandoned technique, engineers at the Massachusetts Institute of Technology (MIT) have successfully created a sophisticated, yet affordable, method to turn ordinary glass into a high-tech solar concentrator.

The technology, which uses dye-coated glass to collect and channel photons otherwise lost from a solar panel's surface, could eventually enable an office building to draw energy from its tinted windows as well as its roof.

Electrical engineer Marc Baldo, his graduate students Michael Currie, Jon Mapel and Timothy Heidel, and postdoctoral associate Shalom Goffri, announced their findings in the July 11 issue of Science.

"We think this is a practical technology for reducing the cost of solar power," said Baldo.

The scientists coated glass panels with layers of two or more light-capturing dyes. The dyes absorbed incoming light and then re-emitted the energy into the glass, which served as a conduit to channel the light to solar cells along the panels' edges. The dyes can vary from bright colors to chemicals that are mostly transparent to visible light.

Because the edges of the glass panels are so thin, far less semiconductor material is needed to collect the light energy and convert that energy into electricity......... Posted by: Kevin      Read more         Source

July 9, 2008, 9:19 PM CT

Controlling the Size of Nanoclusters

Scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Stony Brook University have developed a new instrument that allows them to control the size of nanoclusters - groups of 10 to 100 atoms - with atomic precision. They created a model nanocatalyst of molybdenum sulfide, the first step in developing the next generation of materials to be used in hydrodesulfurization, a process that removes sulfur from natural gas and petroleum products to reduce pollution.

As published in the July 9, 2008 online edition of the Journal of Physical Chemistry C, the researchers made size-selected molybdenum sulfide nanoclusters as gaseous ions, and then gently deposited the clusters on a gold surface. The nanoclusters interact weakly with the gold support and therefore remain intact.

"With this new instrument, we can control how a number of and what type of atoms are in a nanocluster," said Brookhaven chemist Michael White, the principal author of the paper. "This knowledge enables us to make nanoclusters with predetermined size, structure and chemical composition, all which are important for the design of new catalysts."

Currently, molybdenum sulfide nanoparticles are used for hydrodesulfurization and other chemical processes, but it is not known what size is most active or how the reactions occur on small particles. The ability to make model nanocatalysts containing molybdenum sulfide particles of variable size and chemical makeup will allow White and coworkers to understand how current catalysts work and help design the next generation of catalysts......... Posted by: Kevin      Read more         Source

June 26, 2008, 8:50 PM CT

New Nano Technique Significantly Boosts Boiling Efficiency

Whoever penned the old adage "a watched pot never boils" surely never tried to heat up water in a pot lined with copper nanorods.

A new study from scientists at Rensselaer Polytechnic Institute shows that by adding an invisible layer of the nanomaterials to the bottom of a metal vessel, an order of magnitude less energy is mandatory to bring water to boil. This increase in efficiency could have a big impact on cooling computer chips, improving heat transfer systems, and reducing costs for industrial boiling applications.

"Like so a number of other nanotechnology and nanomaterials breakthroughs, our discovery was completely unexpected," said Nikhil A. Koratkar, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer, who led the project. "The increased boiling efficiency seems to be the result of an interesting interplay between the nanoscale and microscale surfaces of the treated metal. The potential applications for this discovery are vast and exciting, and we're eager to continue our investigations into this phenomenon."

Bringing water to a boil, and the related phase change that transforms the liquid into vapor, requires an interface between the water and air. In the example of a pot of water, two such interfaces exist: at the top where the water meets air, and at the bottom where the water meets tiny pockets of air trapped in the microscale texture and imperfections on the surface of the pot. Even though most of the water inside of the pot has reached 100 degrees Celsius and is at boiling temperature, it cannot boil because it is surrounded by other water molecules and there is no interface - i.e., no air - present to facilitate a phase change......... Posted by: Kevin      Read more         Source

June 26, 2008, 8:42 PM CT

Quantum computing breakthrough

The odd behavior of a molecule in an experimental silicon computer chip has led to a discovery that opens the door to quantum computing in semiconductors.

In a Nature Physics journal paper currently online, the scientists describe how they have created a new, hybrid molecule in which its quantum state can be intentionally manipulated - a mandatory step in the building of quantum computers.

"Up to now large-scale quantum computing has been a dream," says Gerhard Klimeck, professor of electrical and computer engineering at Purdue University and associate director for technology for the national Network for Computational Nanotechnology.

"This development may not bring us a quantum computer 10 years faster, but our dreams about these machines are now more realistic".

The workings of traditional computers haven't changed since they were room-sized behemoths 50 years ago; they still use bits of information, 1s and 0s, to store and process information. Quantum computers would harness the strange behaviors found in quantum physics to create computers that would carry information using quantum bits, or qubits. Computers would be able to process exponentially more information.

If a traditional computer were given the task of looking up a person's phone number in a telephone book, it would look at each name in order until it found the right number. Computers can do this much faster than people, but it is still a sequential task. A quantum computer, however, could look at all of the names in the telephone book simultaneously......... Posted by: Kevin      Read more         Source

June 26, 2008, 8:25 PM CT

3-D Nanostructures with Magnetic Materials

Materials researchers at the National Institute of Standards and Technology (NIST) have developed a process to build complex, three-dimensional nanoscale structures of magnetic materials such as nickel or nickel-iron alloys using techniques compatible with standard semiconductor manufacturing. The process, described in a recent paper,* could enable whole new classes of sensors and microelectromechanical (MEMS) devices.

The NIST team also demonstrated that key process variables are associated with relatively quick and inexpensive electrochemical measurements, pointing the way to a fast and efficient way to optimize the process for new materials.

The NIST process is a variation of a technique called "Damascene metallization" that often is used to create complicated three-dimensional copper interconnections, the "wiring" that links circuit elements across multiple layers in advanced, large-scale integrated circuits. Named after the ancient art of creating designs with metal-in-metal inlays, the process involves etching complex patterns of horizontal trenches and vertical "vias" in the surface of the wafer and then uses an electroplating process to fill them with copper. The high aspect ratio features may range from tens of nanometers to hundreds of microns in width. Once filled, the surface of the disk is ground and polished down to remove the excess copper, leaving behind the trench and via pattern......... Posted by: Kevin      Read more         Source

June 23, 2008, 8:01 PM CT

A look into the nanoscale

Lawrence Livermore National Laboratory scientists have captured time-series snapshots of a solid as it evolves on the ultra-fast timescale.

Using femtosecond X-ray free electron laser (FEL) pulses, the team, led by Anton Barty, is able to observe condensed phase dynamics such as crack formation, phase separation, rapid fluctuations in the liquid state or in biologically relevant environments.

Other Livermore researchers include Michael Bogan, Stafan Hau-Riege, Stefano Marchesini, Matthias Frank, Bruce Woods, former Livermore researcher Saša Bajt and former LLNL scientist Henry Chapman, who is now at the Centre for Free Electron Laser Science, DESY, in Hamburg, Gera number of.

"The ability to take images in a single shot is the key to studying non-repetitive behavior mechanisms in a sample," Barty said.

As the femtosecond laser blasts the sample, it is destroyed, but not before the researchers created images with a 50-nanometer spatial resolution, and a 10-femtosecond shutter speed. (A femtosecond is one billionth of one millionth of a second. For context, a femtosecond is to a second as a second is to about 32 million years.).

"This experiment opens the door to a new regime of time-resolved experiments in mesoscopic dynamics," Barty said. "This technique could be extended to a few nanometers spatial and a few tens of femtoseconds temporal resolution"......... Posted by: Kevin      Read more         Source

June 23, 2008, 7:19 PM CT

Light-Driven Reversible Nanoswitches

The ability to see is based on molecules in the eye that flip from one conformation to another when exposed to visible light. Now, a new technique for attaching light-sensitive organic molecules to metal surfaces allows the molecules to be switched between two different configurations in response to exposure to different wavelengths of light. Because the configuration changes are reversible and can be controlled without direct contact, this technique could enable applications that can be controlled at the molecular scale.

The technology has been suggested as a possible basis for molecular motors, artificial muscles, and molecular electronics. The research results, obtained by a team led by Paul S. Weiss, distinguished professor of chemistry and physics at Penn State University and James M. Tour, Chao professor of chemistry at Rice University, are published in the June 2008 issue of the journal Nano Letters.

Until now, progress was impeded because, when such molecules were attached to surfaces, they no longer could be switched back and forth, as they could be when they were in solution. The new technique uses a change in the shape of an azobenzene molecule in response to light to provide two different states. The azobenzene molecule consists of a bridge of two nitrogen atoms attached to one another by a double bond, with each nitrogen atom also bound to a benzene ring. The two benzene rings can be on the same side of the molecule (cis configuration) or on opposite sides (trans configuration). When the molecule absorbs energy, in the form of light, it can change between cis and trans configurations in a process called photoisomerization. "This mechanism is essentially the same that we use in our eyes for vision," said Weiss. "The molecule responds to light by making a change that can be harnessed. In the eye, the change causes a neural impulse"......... Posted by: Kevin      Read more         Source

June 9, 2008, 8:43 PM CT

Interfering with the Global Positioning System

You can't always trust your GPS gadget. As researchers have long known, perplexing electrical activity in the upper atmospheric zone called the ionosphere can tamper with signals from GPS satellites.

Now, new research and monitoring systems are clarifying what happens to disruptive clouds of electrons and other electrically charged particles, known as ions, in the ionosphere. The work may lead to regional predictions of reduced GPS reliability and accuracy.

One team of scientists has recently observed Earth's aurora, which is a prominent manifestation of ionospheric electrical activity, in the act of disrupting GPS equipment. Other researchers have successfully tested a way to forecast GPS disturbances for marine users, with likely extension to users on land.

Some research groups are turning the tables and employing GPS receivers as tools with which to conduct basic research on the electrical-current structures of the ionosphere.

The scientific reports on these and other recent developments are available in a special section of Space Weather: The International Journal of Research and Applications, a publication of the American Geophysical Union, or AGU.

A magazine-style article that introduces the section was posted online Friday, June 6. It summarizes past research and operational developments regarding ionospheric effects on GPS, and discusses potential future improvements in the field......... Posted by: Jim      Read more         Source

June 4, 2008, 10:49 PM CT

Prototype Hydrogen Storage Tank

A cryogenic pressure vessel developed and installed in an experimental hybrid vehicle by a Lawrence Livermore National Laboratory research team can hold liquid hydrogen for six days without venting any of the fuel.

Unlike conventional liquid hydrogen (LH2 tanks in prototype cars, the LLNL pressure vessel was parked for six days without venting evaporated hydrogen vapor.

The LLNL development has significantly increased the amount of time it takes to start releasing hydrogen during periods of long-term parking, as in comparison to today's liquid hydrogen tanks capable of holding hydrogen for merely two to four days.

LH2 tanks hold super-cold liquid hydrogen at around -420 Fahrenheit. Like water boiling in a tea kettle, pressure builds as heat from the environment warms the hydrogen inside. Current automotive LH2 tanks must vent evaporated hydrogen vapor after being parked three to four days, even when using the best thermal insulation available (200 times less conductive than Styrofoam insulation).

In recent testing of its prototype hydrogen tank onboard a liquid hydrogen (LH2) powered hybrid, LLNL's tank demonstrated a thermal endurance of six days and the potential for as much as 15 days, helping resolve a key challenge facing LH2 automobiles......... Posted by: Sarah      Read more         Source

May 27, 2008, 9:37 PM CT

Robots go Where Scientists Fear to Tread

Researchers are diligently working to understand how and why the world's ice shelves are melting. While most of the data they need (temperatures, wind speed, humidity, radiation) can be obtained by satellite, it isn't as accurate as good old-fashioned, on-site measurement and static ground-based weather stations don't allow researchers to collect info from as a number of locations as they'd like.

Unfortunately, the locations in question are volatile ice sheets, possibly cracking, shifting and filling with water - not exactly a safe environment for scientists.

To help researchers collect the more detailed data they need without risking scientists' safety, scientists at the Georgia Institute of Technology, working with Pennsylvania State University, have created specially designed robots called SnoMotes to traverse these potentially dangerous ice environments. The SnoMotes work as a team, autonomously collaborating among themselves to cover all the necessary ground to gather assigned scientific measurements. Data gathered by the Snomotes could give researchers a better understanding of the important dynamics that influence the stability of ice sheets.

"In order to say with certainty how climate change affects the world's ice, researchers need accurate data points to validate their climate models," said Ayanna Howard, lead on the project and an associate professor in the School of Electrical and Computer Engineering at Georgia Tech. "Our goal was to create rovers that could gather more accurate data to help researchers create better climate models. It's definitely science-driven robotics."........ Posted by: Kevin      Read more         Source

Sat, 24 May 2008 22:29:15 GMT

Nanotechnology for Dummies

Don't you just love the "for dummies" series? I hope the title doesn't personally offend anyone. I'm not calling anyone a dummy. I just like the book series.

So, have you read Nanotechnology for Dummies? This book is great because it breaks down the science into a simple, yet meaningful explanation. Many people have misconceptions about what nanotechnology is about. Some think that nanotechnology is just about microscopic robots. Others think that nanotechnology only applies to microchips and computer technology.

It's easy reading and also serves as a nice gift if you're ever in need of one. Visit Dummies.com to see all the other "for dummies" books. Posted by: Joseph Kim, MD      Read more     Source

May 19, 2008, 8:43 PM CT

Researchers Create Superior Polymer

Scientists at Northwestern University and Princeton University have created a new kind of polymer that, because of its extraordinary thermal and mechanical properties, could be used in everything from airplanes to solar cells.

The polymer, a nanocomposite that incorporates functionalized, exfoliated graphene sheets, even conducts electricity, and scientists hope to use that property to eventually create thermally stable, optically transparent conducting polymers.

The results of their research were published May 11 in the online version of Nature Nanotechnology.

Researcher at the McCormick School of Engineering originally teamed up with scientists at Princeton several years ago. McCormick scientists had experience working with polymer nanocomposites, and Princeton scientists had developed a way to exfoliate, or split apart, graphite sheets into very thin single layer, surface-functionalized graphene sheets.

Prior use of graphite in polymers did not garner significantly improved properties since scientists could never get the graphite exfoliated. That meant the graphite was rigid with a low surface area and could only minimally impact properties of the polymer.

But when scientists put even a small amount the newly exfoliated graphene sheets - enough to equal only.05 percent of the material - into the polymer, they found the graphene changed the polymer's thermal stability temperature by 30 degrees. Even adding graphene sheets equal to.01 percent of the material increased stiffness by 33 percent - far beyond what scientists had predicted. The drastic changes in both the thermal stability and the stiffness after adding just a tiny percentage of functionalized graphene indicated that the graphene changes large regions of the polymer radiating out from the nanoparticle surfaces in a percolating network structure......... Posted by: Kevin      Read more         Source

May 19, 2008, 6:34 PM CT

Mid-Infrared Lasers Show Doubled Efficiency

Scientists at the Center for Quantum Devices at the McCormick School of Engineering at Northwestern University have recently doubled the efficiency of infrared lasers under the U.S. Defense Advanced Research Projects Agency's Efficient Mid-wave Infrared Lasers (EMIL) program.

As these types of lasers become more efficient, they could be used in next-generation laser-based defense systems to fool incoming missile attacks or detect explosives or toxins in the atmosphere. Such lasers could also be used in commercial applications like trace chemical analysis, pollution monitoring, and free space communication.

But first, scientists must find the right laser sources at the right wavelengths. The mid-infrared wavelength range (3 to 5 microns) is particularly useful for defense-based applications, and laser technology in this range has been targeted by the U.S. Defense Advanced Research Projects Agency (DARPA) as a strategic technology. The agency created the EMIL program to develop high efficiency, compact semiconductor laser sources with the hopes of demonstrating both high power (~1 W) and high power efficiency (50 percent) from an individual laser at room temperature. Besides demonstrating a significant energy savings over currently available sources, this technology (the quantum cascade laser) will also be more compact than any other laser technology for this wavelength range and operating temperature, with an active volume that is smaller than a human hair......... Posted by: Kevin      Read more         Source

May 18, 2008, 10:05 PM CT

Nanosoccer Robots in Action in Pittsburgh

Nanosoccer returns to the field later this month, when the National Institute of Standards and Technology (NIST) hosts for the second time the world's most Lilliputian sport. Three student teams will participate in a public exhibition at the 2008 U.S. "RoboCup Open" in Pittsburgh, Pa., May 25 to 27, where miniature "soccer players"-computer-driven robots six times smaller than an amoeba operating on a field the size of a grain of rice-will show off their skills.

The teams from Carnegie-Mellon University (Pittsburgh, Pa.), the U.S. Naval Academy (Annapolis, Md.) and the University of Waterloo (Waterloo, Ontario, Canada) will meet at the Carnegie Science Center in Pittsburgh, Pa., to put their nanobots (nanoscale robots) through their paces. The nanobots will be demonstrating agility, maneuverability, response to computer control and ability to move objects-all tools that future miniaturized mechanized workers will need for tasks such as microsurgery within the human body or the manufacturing of atom-sized components for microscopic electronic devices.

RoboCup is an annual international competition designed to foster innovations and advances in artificial intelligence and intelligent robotics by using the game of soccer as a testing ground. NIST's goal in coordinating competitions between the world's smallest robots is to show the feasibility and accessibility of technologies for fabricating MicroElectroMechanical Systems (MEMS), tiny mechanical devices built onto semiconductor chips and measured in micrometers (millionth of a meter)......... Posted by: Kevin      Read more         Source

May 15, 2008, 7:31 PM CT

Gravity-defying bird beak mystery

As Charles Darwin showed nearly 150 years ago, bird beaks are exquisitely adapted to the birds' feeding strategy. A team of MIT mathematicians and engineers has now explained exactly how some shorebirds use their long, thin beaks to defy gravity and transport food into their mouths.

The phalarope, commonly found in western North America, takes advantage of surface interactions between its beak and water droplets to propel bits of food from the tip of its long beak to its mouth, the research team reports in the May 16 issue of Science.

These surface interactions depend on the chemical properties of the liquid involved, so phalaropes and about 20 other birds species that use this mechanism are extremely sensitive to anything that contaminates the water surface, especially detergents or oil.

"Some species rely exclusively on this feeding mechanism, and so are extremely vulnerable to oil spills," said John Bush, MIT associate professor of applied mathematics and senior author of the paper.

Wildlife biologists have long noted the unusual feeding behavior of phalaropes, which spin in circles on the water, creating a vortex that sweeps small crustaceans up to the surface, just like tea leaves in a swirling tea cup.

The birds peck at the surface, picking up millimetric droplets of water with their prey trapped inside. Since the birds point their beaks downward during the feeding process, gravity must be overcome to get those droplets from the tip of the bird's long beak to its mouth. Until now, scientists have been puzzled as to how that happens......... Posted by: Ashley      Read more         Source

May 11, 2008, 10:22 AM CT

Evolution of "gas giants"

By shooting the high-energy Omega laser onto precompressed samples of planetary fluids, researchers are gaining a better understanding of the evolution and internal structure of Jupiter, Saturn and extrasolar giant planets.

The properties of dense helium (He) - which happens to be a principal constituent of giant gas planets like Jupiter - at thermodynamic conditions between those of condensed matter and high-temperature plasmas are theoretically challenging and unexplored experimentally.

Laboratory researchers collaborating with scientists at the Laboratory for Laser Energetics, CEA France and UC Berkeley were able to determine the equation of state (EOS) for fluid He at pressures above 100 GPa (one million times more pressure than the Earth's atmosphere - one GPa (gigapascal) equals 10,000 atmospheres).

The only prior high temperature and pressure He EOS data available for constraining planetary models waccording toformed at LLNL by Bill Nellis and his team using a two-stage gas gun. However, those earlier experiments used cryogenic techniques at ambient pressure so their densities were significantly lower than those achieved with the precompressed samples. Also, the final pressures, 16 GPa for a single shock, were significantly lower than the new laser shock data......... Posted by: Kevin      Read more         Source

May 11, 2008, 10:18 AM CT

Pressure Effects On Nanomaterials

Transistors, lasers and solar-energy conversion devices may be easier to manipulate because of recent research by Lawrence Livermore National Laboratory scientists.

The scientists defined the role high pressure plays in precisely tuning the fundamental properties of nanomaterials and, in particular, nanoparticle assemblies that are important for device applications.

The team, made up of LLNL researchers Christian Grant, Jonathan Crowhurst, Sebastien Hamel, Natalia Zaitseva and former LLNL researcher Andrew Williamson (now at Physic Ventures), subjected quantum dot solids (in this case assemblies of cadmium selenide, or CdSe, nanocrystals) to very high static pressures on the order of 70,000 atmospheres and studied in-situ their response using a laser-based luminescence technique. A quantum dot is a semiconductor whose electrons are confined in all three spatial dimensions.

"We closely compared our results with theoretical calculations," Grant said. "These results were completely consistent with our experimental observations".

But when they applied nonuniform pressure, the results were quite different.

It led to large shifts in the energy linked to the very strong fluorescence of CdSe. CdSe, it was found, is extremely sensitive to the local stress state......... Posted by: Kevin      Read more         Source

May 11, 2008, 9:14 AM CT

Designer Isotopes Push the Frontier of Science

Designer labels have a lot of cachet, a principle that's equally true in fashion and physics.

The future of nuclear physics is in designer isotopes--the relatively new power researchers have to make specific rare isotopes to solve scientific problems and open doors to new technologies, as per Bradley Sherrill, a University distinguished professor of physics and associate director for research at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU).

"We have developed a remarkable capability over the last 10 or so years that allows us to build a specific isotope to use in research," Sherrill said. "It is a new tool that promises to allow whole new directions in research to move forward. There are tremendous advances that are possible".

Sherrill outlined some of the possibilities and what it will take to get there in a perspective piece in the May 9 edition of Science magazine.

In that article, he writes nanotechnology is getting a lot of attention for the astonishing possibilities of constructing objects with individual atoms and molecules. Sherrill, however, said that nanotechnology hardly is the last word in small.

The chemical changes that brought about the formation of the elements in the bellies of stars are being recreated in laboratories such as MSU's NSCL. Advances in basic nuclear science already have given way to technologies such as PET (short for positron emission tomography) scans, which are medical procedures that use special isotopes to target specific types of tumors......... Posted by: Sarah      Read more         Source

April 30, 2008, 5:20 PM CT

Heat transfer between materials

Managing heat is a major challenge for engineers who work on devices from jet engines to personal electronics to nano-scale transistors.

A team led by a University of Michigan mechanical engineer has received a five-year, $6.8-million grant from the Air Force to examine this problem, which is a barrier to more powerful, efficient devices.

Led by Kevin Pipe, an assistant professor in the Department of Mechanical Engineering, the team has received a Multidisciplinary University Research Initiative (MURI) award from the Air Force Office of Scientific Research. The research group includes nine researchers and engineers from three universities, including Brown University and the University of California at Santa Cruz.

"The processes by which heat is transferred at interfaces between different materials are poorly understood," Pipe said. "But in a number of systems, the ability to either efficiently transfer or block heat flow from one material to another is critically important to performance and reliability".

Inefficient heat flow is a main roadblock in the development of lasers and transistors that can attain higher powers. Conversely, blocking heat exchange can dramatically improve the efficiency of thermoelectric energy conversion for compact power sources......... Posted by: Kevin      Read more         Source