Through a broad agency announcement, the Air Force Next Generation Space Processor Analysis Program is seeking two to four companies to perform a yearlong evaluation of advanced, space-based applications that would use spaceflight processors for the 2020-2030 time frame.

NASA's decision to partner with the Air Force and issue a joint solicitation was influenced by a four-month formulation study funded by NASA's Space Technology Mission Directorate's Game Changing Development Program.

During that investigation, engineers from NASA's Goddard Space Flight Center in Greenbelt, Md., NASA's Jet Propulsion Laboratory in Pasadena, Calif., the Johnson Space Center in Houston, and NASA's Ames Research Center in Moffett Field, Calif., evaluated 19 real-life mission scenarios involving the use of flight processors.

"We surveyed NASA's needs and it became more than obvious that we could take advantage of an advanced processor," said Richard Doyle, the program manager for JPL's Information and Data Science Program and study leader.

By any standard, NASA's state-of-the-art is significantly less capable than what is available in most consumer products, said Wes Powell, a NASA Goddard engineer who participated in the study.

"We have special requirements," Doyle said. "Our flight needs are more extreme and our processors must be able to perform robustly in a radiation environment, using low power." As a result, both military and civilian mission planners must use specialized, vastly more expensive processors that have been hardened against radiation-induced upsets and generally have a higher degree of fault tolerance.

Limitations of the Current State-of-the-Art
The current state-of-the-art - the RAD750 - is a single-board computer manufactured by BAE Systems Electronic Solutions. Specifically designed to operate in high-radiation environments like those encountered in space, BAE released the technology in 2001 as the successor to the RAD6000.

As of 2010, the RAD750 had become de rigueur for a broad range of space missions, including the Curiosity rover, the Solar Dynamics Observatory and the Fermi Gamma-ray Space Telescope, among others.

Though it's hardened against radiation-induced upsets and uses only five watts of power - another important performance requirement in energy-constrained spaceflight missions - the RAD750 computes only 200 million operations per second.

To get around these computational limitations, mission designers are implementing highly customized processors featuring more powerful, radiation-hardened, field-programmable gate arrays, which are capable of implementing application-specific processing circuitry.

While these custom-designed processing solutions handle heavier data loads, they can be difficult and time consuming to program, and aren't as power-efficient for general purpose processing, Powell said.

"What NASA needs is an energy-efficient general-purpose processor capable of billions of operations per second, thereby making it applicable to most missions," Powell said. "The bottom line is that while the RAD750 has been very successful, it is generations behind the current state-of-the-art."

Baselines Multi-Core Technology
In addition to establishing the rationale for a technology investment, the team surveyed six different architectures and decided that multi-core processing satisfied NASA's objectives.

With multi-core technology, a single physical processor contains the core logic of several processors, which are packaged into a single integrated circuit. Multi-core technology is used in desktops, mobile PCs, servers and workstations, and allows the system to perform more tasks and scale its energy consumption, depending on what is needed at the time.

This isn't to say that the effort won't face challenges. "The key challenges are processing throughput, radiation and fault tolerance, power efficiency, and the ability to broadly scale power and performance, using no more than seven watts," Powell said.

The time for change, however, is now, he said. "We need a significant increase in performance and power efficiency. A small incremental improvement won't justify the investment. The development of a spaceflight multi-core processor will provide transformational improvements in onboard processing for NASA's future missions."

The NASA - Air Force call for proposals was made in April by NASA's Space Technology Mission Directorate, which is innovating, developing, testing and flying hardware for use in future science and exploration missions.

]]> Mon, 20 MAY 2013 12:42:42 AEST Cambridge MA (SPX) May 17, 2013 - Graphene has dazzled scientists, ever since its discovery more than a decade ago, with its unequalled electronic properties, its strength and its light weight. But one long-sought goal has proved elusive: how to engineer into graphene a property called a band gap, which would be necessary to use the material to make transistors and other electronic devices.

Now, new findings by researchers at MIT are a major step toward making graphene with this coveted property. The work could also lead to revisions in some theoretical predictions in graphene physics.

The new technique involves placing a sheet of graphene - a carbon-based material whose structure is just one atom thick - on top of hexagonal boron nitride, another one-atom-thick material with similar properties. The resulting material shares graphene's amazing ability to conduct electrons, while adding the band gap necessary to form transistors and other semiconductor devices.

The work is described in a paper in the journal Science co-authored by Pablo Jarillo-Herrero, the Mitsui Career Development Assistant Professor of Physics at MIT, Professor of Physics Ray Ashoori, and 10 others.

"By combining two materials," Jarillo-Herrero says, "we created a hybrid material that has different properties than either of the two."

Graphene is an extremely good conductor of electrons, while boron nitride is a good insulator, blocking the passage of electrons. "We made a high-quality semiconductor by putting them together," Jarillo-Herrero explains. Semiconductors, which can switch between conducting and insulating states, are the basis for all modern electronics.

To make the hybrid material work, the researchers had to align, with near perfection, the atomic lattices of the two materials, which both consist of a series of hexagons. The size of the hexagons (known as the lattice constant) in the two materials is almost the same, but not quite: Those in boron nitride are 1.8 percent larger. So while it is possible to line the hexagons up almost perfectly in one place, over a larger area the pattern goes in and out of register.

At this point, the researchers say they must rely on chance to get the angular alignment for the desired electronic properties in the resulting stack. However, the alignment turns out to be correct about one time out of 15, they say.

"The qualities of the boron nitride bleed over into the graphene," Ashoori says. But what's most "spectacular," he adds, is that the properties of the resulting semiconductor can be "tuned" by just slightly rotating one sheet relative to the other, allowing for a spectrum of materials with varied electronic characteristics.

Others have made graphene into a semiconductor by etching the sheets into narrow ribbons, Ashoori says, but such an approach substantially degrades graphene's electrical properties. By contrast, the new method appears to produce no such degradation.

The band gap created so far in the material is smaller than that needed for practical electronic devices; finding ways of increasing it will require further work, the researchers say.

"If ... a large band gap could be engineered, it could have applications in all of digital electronics," Jarillo-Herrero says. But even at its present level, he adds, this approach could be applied to some optoelectronic applications, such as photodetectors.

The results "surprised us pleasantly," Ashoori says, and will require some explanation by theorists. Because of the difference in lattice constants of the two materials, the researchers had predicted that the hybrid's properties would vary from place to place. Instead, they found a constant, and unexpectedly large, band gap across the whole surface.

In addition, Jarillo-Herrero says, the magnitude of the change in electrical properties produced by putting the two materials together "is much larger than theory predicts."

The MIT team also observed an interesting new physical phenomenon. When exposed to a magnetic field, the material exhibits fractal properties - known as a Hofstadter butterfly energy spectrum - that were described decades ago by theorists, but thought impossible in the real world. There is intense research in this area; two other research groups also report on these Hofstadter butterfly effects this week in the journal Nature.

The research included postdocs Ben Hunt and Andrea Young and graduate student Javier Sanchez-Yamagishi, as well as six other researchers from the University of Arizona, the National Institute for Materials Science in Tsukuba, Japan, and Tohoku University in Japan. The work is described in a paper in the journal Science co-authored by Pablo Jarillo-Herrero, the Mitsui Career Development Assistant Professor of Physics at MIT, Professor of Physics Ray Ashoori, and 10 others.

]]> Mon, 20 MAY 2013 12:42:42 AEST Stanford CA (SPX) May 17, 2013 - One of the exciting possibilities of metamaterials - engineered materials that exhibit properties not found in the natural world - is the potential to control light in ways never before possible. The novel optical properties of such materials could lead to a "perfect lens" that allows direct observation of an individual protein in a light microscope or, conversely, invisibility cloaks that completely hide objects from sight.

Although metamaterials have revolutionized optics in the past decade, their performance so far has been inhibited by their inability to function over broad bandwidths of light. Designing a metamaterial that works across the entire visible spectrum remains a considerable challenge.

Now, Stanford engineers have taken an important step toward this future, by designing a broadband metamaterial that more than doubles the range of wavelengths of light that can be manipulated.

The new material can exhibit a refractive index - the degree to which a material skews light's path - well below anything found in nature.

"The library of refractive indexes that nature gives us is limited," said Jennifer Dionne, an assistant professor of materials science and engineering and an affiliate member of the Stanford Institute for Materials and Energy Sciences at SLAC National Accelerator Laboratory. "All natural materials have a positive refractive index."

For example, air at standard conditions has the lowest refractive index in nature, hovering just a tick above 1. The refractive index of water is 1.33. That of diamond is about 2.4. The higher a material's refractive index, the more it distorts light from its original path.

Really interesting physical phenomena can occur, however, if the refractive index is near-zero or negative.

Picture a drinking straw leaning in a glass of water. If the water's refractive index were negative, the straw would appear inverted - a straw leaning left to right above the water would appear to slant right to left below the water line.

In order for invisibility cloak technology to obscure an object or for a perfect lens to inhibit refraction, the material must be able to precisely control the path of light in a similar manner. Metamaterials offer this potential.

Unlike a natural material whose optical properties depend on the chemistry of the constituent atoms, a metamaterial derives its optical properties from the geometry of its nanoscale unit cells, or "artificial atoms." By altering the geometry of these unit cells, one can tune the refractive index of the metamaterial to positive, near-zero or negative values.

One hitch is that any such material needs to interact with both the electric and magnetic fields of light. Most natural materials are blind to the magnetic field of light at visible and infrared wavelengths.

Previous metamaterial efforts have created artificial atoms composed of two constituents - one that interacts with the electric field, and one for the magnetic. A drawback to this combination approach is that the individual constituents interact with different colors of light, and it is typically difficult to make them overlap over a broad range of wavelengths.

As detailed in the cover story of the current issue of Advanced Optical Materials, Dionne's group - which included graduate students Hadiseh Alaeian and Ashwin Atre, and postdoctoral fellow Aitzol Garcia - set about designing a single metamaterial "atom" with characteristics that would allow it to efficiently interact with both the electric and magnetic components of light.

The group arrived at the new shape using complex mathematics known as transformation optics. They began with a two-dimensional, planar structure that had the desired optical properties, but was infinitely extended (and so would not be a good "atom" for a metamaterial).

Then, much like a cartographer transforms a sphere into a flat plane when creating a map, the group "folded" the two-dimensional infinite structure into a three-dimensional nanoscale object, preserving the original optical properties.

The transformed object is shaped like a crescent moon, narrow at the tips and thick in the center; the metamaterial consists of these nanocrescent "atoms" arranged in a periodic array.

As currently designed, the metamaterial exhibits a negative refractive index over a wavelength range of roughly 250 nanometers in multiple regions of the visible and near-infrared spectrum. The researchers said that a few tweaks to its structure would make this metamaterial useful across the entire visible spectrum.

"We could tune the geometry of the crescent, or shrink the atom's size, so that the metamaterial would cover the full visible light range, from 400 to 700 nanometers," Atre said.

That composite material probably won't resemble an invisibility cloak like Harry Potter's anytime soon; while it could be flexible, manufacturing the metamaterial over extremely large areas could be tricky. Nonetheless, the authors are excited about the research opportunities the new material will open.

"Metamaterials will potentially allow us to do many new things with light, things we don't even know about yet. I can't even imagine what all the applications might be," Garcia said. "This is a new tool kit to do things that have never been done before."

This report was published in the current issue of Advanced Optical Materials

]]> Mon, 20 MAY 2013 12:42:42 AEST Innsbruck, Austria (SPX) May 17, 2013 - Below a critical temperature, certain fluids become superfluid and lose internal friction. In addition, fluids in this state conduct heat extremely efficiently, with energy transport occurring in a distinct temperature wave. Because of the similarities to a sound wave, this temperature wave is also called second sound.

To explain the nature of superfluids, the famous physicist Lev Landau developed the theory of two-fluid hydrodynamics in Moscow in 1941. He assumed that fluids at these low temperatures comprise a superfluid and a normal component, whereby the latter one gradually disappears with decreasing temperature.

Until now superfluidity has experimentally been observed only in liquid helium and in ultracold quantum gases. Another example of a superfluid system is a neutron star, and evidence also been found in the atomic nucleus.

Superfluidity is closely connected to the technologically important superconductivity, the phenomenon of zero electrical resistance at very low temperatures.

Observation of temperature waves
Ultracold quantum gases are ideal model systems to experimentally observe quantum mechanical phenomena such as superfluidity. In these experiments hundreds of thousands of atoms are cooled in a vacuum chamber to almost absolute zero (-273.15 C). By using lasers the particles in this state can be controlled and manipulated efficiently and with high accuracy.

"Despite intensive research in this field for over ten years now, the phenomenon of second sound has proven elusive for detection in quantum gases," says Rudolf Grimm from the Institute of Experimental Physics at the University of Innsbruck and the Institute of Quantum Optics and Quantum Information at the Austrian Academy of Sciences.

"However, in the end it was amazingly easy to prove." In the laboratory, Grimm's team of quantum physicists prepared a quantum gas consisting of about 300,000 lithium atoms. They heated the cigar-shaped particle cloud locally with a power-modulated laser beam and then observed the propagating temperature wave.

"While in superfluid helium only one entropy wave is generated, our Fermi gas also exhibited some thermal expansion and, thus, a measurable density wave," explains Grimm the crucial difference. It was also the first time that the Innsbruck physicists were able to measure the superfluid fraction in the quantum gas.

"Before us nobody had been able to achieve this, which closes a fundamental gap in the research of Fermi gases," says Rudolf Grimm.

Confirming a theory after 50 years
The research work, published now in the journal Nature, is the result of a long-term close collaboration between the physicists in Innsbruck and the Italian scientists.

The theoretical physicists from the Trento Bose-Einstein Condensation Center led by Sandro Stringari and Lev Pitaevskii adapted Lev Landau's theory of the description of second sound for the almost one-dimensional geometry of the Innsbruck experiments. Actually Lev Pitaevskii was one of Lev Landau's pupils.

"With this model it became easy to interpret the results of our measurement," says Rudolf Grimm.

"Moreover, our colleagues from Trento intensely supported our experiment conceptually. The results represent the pinnacle of the collaboration with our partner university in Trento and it is a vital indication for research cooperation within the European Region the Tyrol-South Tyrol-Trentino."

In June the University of Innsbruck will award an Honorary Doctorate to Lev Pitaevskii for his close collaboration with the local scientists.

The scientists are supported by the Austrian Science Fund (FWF) and the European Research Council (ERC).

]]> Mon, 20 MAY 2013 12:42:42 AEST Baltimore MD (SPX) May 17, 2013 - Northrop Grumman Scalable Agile Beam Radar (SABR) designed for the F-16 fighter aircraft recently demonstrated its autonomous, all-environment precision targeting capability, which will enhance the aircraft's mission capabilities.

The capability, known as Auto Target Cueing (ATC), uses high-definition synthetic aperture radar (SAR) images to locate and prioritize targets of interest and display them to the pilot. The active electronically scanned array (AESA) radar architecture allows it to carry out this function while performing other tasks at the same time.

"With SABR, we have built on our F-35 radar investment to bring fifth generation fighter radar capabilities such as ATC to the F-16," said Joseph Ensor, vice president and general manager of Northrop Grumman's Intelligence, Surveillance, Reconnaissance and Targeting Systems Division.

"Features like ATC, along with the F-35 modes that we have ported to SABR, will enable greater mission effectiveness, reduce pilot workload and provide a better level of situational awareness than F-16 pilots have ever had."

SABR is an affordable, multifunction AESA radar designed specifically for F-16 retrofit. SABR provides longer detection and tracking ranges, high-resolution SAR maps for all-environment precision targeting, interleaved mode operations for greater situational awareness and greater reliability.

Northrop Grumman has nearly four decades of F-16 radar development and integration experience, and has delivered more than 6,000 fire control radars to U.S. and international air forces. The company also supplies the AESA fire control radars for the F-16 Block 60, F-22 and F-35 aircraft.

]]> Mon, 20 MAY 2013 12:42:42 AEST Cambridge MA (SPX) May 17, 2013 - "Spring is like a perhaps hand," wrote the poet E. E. Cummings: "carefully / moving a perhaps / fraction of flower here placing / an inch of air there... / without breaking anything."

With the hand of nature trained on a beaker of chemical fluid, the most delicate flower structures have been formed in a Harvard laboratory-and not at the scale of inches, but microns.

These minuscule sculptures, curved and delicate, don't resemble the cubic or jagged forms normally associated with crystals, though that's what they are. Rather, fields of carnations and marigolds seem to bloom from the surface of a submerged glass slide, assembling themselves a molecule at a time.

By simply manipulating chemical gradients in a beaker of fluid, Wim L. Noorduin, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS) and lead author of a paper appearing on the cover of the May 17 issue of Science, has found that he can control the growth behavior of these crystals to create precisely tailored structures.

"For at least 200 years, people have been intrigued by how complex shapes could have evolved in nature. This work helps to demonstrate what's possible just through environmental, chemical changes," says Noorduin.

The precipitation of the crystals depends on a reaction of compounds that are diffusing through a liquid solution. The crystals grow toward or away from certain chemical gradients as the pH of the reaction shifts back and forth. The conditions of the reaction dictate whether the structure resembles broad, radiating leaves, a thin stem, or a rosette of petals.

It is not unusual for chemical gradients to influence growth in nature; for example, delicately curved marine shells form from calcium carbonate under water, and gradients of signaling molecules in a human embryo help set up the plan for the body.

Similarly, Harvard biologist Howard Berg has shown that bacteria living in colonies can sense and react to plumes of chemicals from one another, which causes them to grow, as a colony, into intricate geometric patterns.

Replicating this type of effect in the laboratory was a matter of identifying a suitable chemical reaction and testing, again and again, how variables like the pH, temperature, and exposure to air might affect the nanoscale structures.

The project fits right in with the work of Joanna Aizenberg, an expert in biologically inspired materials science, biomineralization, and self-assembly, and principal investigator for this research.

Aizenberg is the Amy Smith Berylson Professor of Materials Science at Harvard SEAS, Professor of Chemistry and Chemical Biology in the Harvard Department of Chemistry and Chemical Biology, and a Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering at Harvard.

Her recent work has included the invention of an extremely slippery material, inspired by the pitcher plant, and the discovery of how bacteria use their flagella to cling to the surfaces of medical implants.

"Our approach is to study biological systems, to think what they can do that we can't, and then to use these approaches to optimize existing technologies or create new ones," says Aizenberg. "Our vision really is to build as organisms do."

To create the flower structures, Noorduin and his colleagues dissolve barium chloride (a salt) and sodium silicate (also known as waterglass) into a beaker of water. Carbon dioxide from air naturally dissolves in the water, setting off a reaction which precipitates barium carbonate crystals.

As a byproduct, it also lowers the pH of the solution immediately surrounding the crystals, which then triggers a reaction with the dissolved waterglass. This second reaction adds a layer of silica to the growing structures, uses up the acid from the solution, and allows the formation of barium carbonate crystals to continue.

"You can really collaborate with the self-assembly process," says Noorduin. "The precipitation happens spontaneously, but if you want to change something then you can just manipulate the conditions of the reaction and sculpt the forms while they're growing."

Increasing the concentration of carbon dioxide, for instance, helps to create 'broad-leafed' structures. Reversing the pH gradient at the right moment can create curved, ruffled structures.

Noorduin and his colleagues have grown the crystals on glass slides and metal blades; they've even grown a field of flowers in front of President Lincoln's seat on a one-cent coin.

"When you look through the electron microscope, it really feels a bit like you're diving in the ocean, seeing huge fields of coral and sponges," describes Noorduin. "Sometimes I forget to take images because it's so nice to explore."

In addition to her roles at Harvard SEAS, the Department of Chemistry and Chemical Biology, and the Wyss Institute, Joanna Aizenberg is Director of the Kavli Institute for Bionano Science and Technology at Harvard and Director of the Science Program at the Radcliffe Institute for Advanced Study.

Coauthors included Alison Grinthal, a research scientist at Harvard SEAS, and L. Mahadevan, who is the Lola England de Valpine Professor of Applied Mathematics at SEAS, Professor of Organismic and Evolutionary Biology and of Physics, and a Core Faculty Member at the Wyss Institute.

]]> Mon, 20 MAY 2013 12:42:42 AEST York, UK (SPX) May 15, 2013 - An international team of scientists, including a University of York researcher, has carried out ground-breaking experiments to investigate the atomic structure of astatine (Z=85), the rarest naturally occurring element on Earth.

Astatine (At) is of significant interest as its decay properties make it an ideal short-range radiation source for targeted alpha therapy in cancer treatment.

The results of the project, which was conceived by Professor Andrei Andreyev, an Anniversary Professor in the Department of Physics at the University of York, and Dr Valentine Fedosseev, from CERN, the European laboratory for nuclear physics research in Geneva, are reported in Nature Communications.

Through experiments conducted at the radioactive isotope facility ISOLDE at CERN, scientists have accessed, for the first time, the ionization potential of the astatine atom. This represents the essential quantity defining chemical and physical properties of this exclusively radioactive element.

The successful measurement fills a long-standing gap in Mendeleev's periodic table, since astatine was the last element present in nature for which this fundamental property was unknown.

As binding energy of the outermost valence electron, the atomic ionization energy is highly relevant for the chemical reactivity of an element and, indirectly, the stability of its chemical bonds in compounds.

Professor Andreyev, who moved to York from the University of the West of Scotland last year, said: "Astatine is of particular interest because its isotopes are interesting candidates for the creation of radiopharmaceuticals for cancer treatment by targeted alpha therapy.

"The experimental value for astatine serves also for benchmarking the theories used to predict the atomic and chemical properties of super-heavy elements, in particular the recently discovered element 117, which is a homologue of astatine."

Astatine was discovered by D. Corson and co-workers in 1940 by bombarding a bismuth target with alpha particles. The most stable isotope of this element has a half-life time of only 8.1 hours. In 1964, McLaughlin studied a 70 ng sample of artificially produced radioactive isotopes of astatine and was first to observe two spectral lines in the UV region. Apart from this, no other data on astatine's atomic spectrum was known before the study launched at CERN's ISOLDE.

At ISOLDE, short-lived isotopes created in nuclear reactions induced by a high energy proton beam release from target material and can immediately interact with laser beams inside the hot cavity of laser ion source.

Once the wavelengths of lasers are tuned in resonance with selected atomic transitions the atoms are step-wise excited and ionized due to absorption of several photons with total energy exceeding the ionization threshold. This so-called Resonance Ionization Laser Ion Source (RILIS), in combination with electromagnetic separator, supplies pure isotopic beams of different elements for many experiments performed at ISOLDE.

Among these, is a study of short-lived nuclides by in-source resonance ionization spectroscopy using a highly sensitive (below 1 isotope per second) detection of nuclear decay. Physicists from KU Leuven, Belgium developed the setup for this study. The first laser-ionized ions of astatine were observed and identified by its characteristic alpha-decay in these experiments. Also the ionization threshold of astatine was found by scanning the wavelength of ionizing UV laser.

A second phase of the study of the atomic spectrum of astatine took place at the ISAC radioactive isotope facility of the Canadian national laboratory for particle and nuclear physics TRIUMF in Vancouver, where new optical transitions in the infrared region of spectrum were found. With the newly found transitions a highly efficient three-step ionization scheme of astatine was defined and used at ISOLDE RILIS for further study of astatine spectrum.

The researchers probed the interesting region around the ionization threshold and found a series of highly excited resonances - known as Rydberg states. From this spectrum the first ionization potential of astatine was extracted with high accuracy.

Dr Fedosseev, the RILIS team leader working at CERN, said: "The in-source laser spectroscopy today is a most sensitive method to study atomic properties of exotic short-lived isotopes. For artificially produced elements, like super-heavy ones, this could be a real way to probe their spectra. The success in the study of astatine spectrum added confidence to such projects started recently at GANIL, France and at JINR, Russia."

Professor Andreyev, who joined York as one of 16 Chairs established to mark the University's 50th Anniversary in 2013, added: "This development allows several new phenomena to be investigated, such as the size (radii) of astatine nuclei, along with a very exotic type of nuclear fission. Our collaboration has recently initiated a series of experiments to reach these goals."

]]> Mon, 20 MAY 2013 12:42:42 AEST Berkeley CA (SPX) May 14, 2013 - Bubble baths and soapy dishwater, the refreshing head on a beer and the luscious froth on a cappuccino. All are foams, beautiful yet ephemeral as the bubbles pop one by one.

Two University of California, Berkeley, researchers have now described mathematically the successive stages in the complex evolution and disappearance of foamy bubbles, a feat that could help in modeling industrial processes in which liquids mix or in the formation of solid foams such as those used to cushion bicycle helmets.

Applying these equations, they created mesmerizing computer-generated movies showing the slow and sedate disappearance of wobbly foams one burst bubble at a time.

The applied mathematicians, James A. Sethian and Robert I. Saye, will report their results in the May 10 issue of Science. Sethian, a UC Berkeley professor of mathematics, leads the mathematics group at Lawrence Berkeley National Laboratory (LBNL). Saye will graduate from UC Berkeley this May with a PhD in applied mathematics.

"This work has application in the mixing of foams, in industrial processes for making metal and plastic foams, and in modeling growing cell clusters," said Sethian. "These techniques, which rely on solving a set of linked partial differential equations, can be used to track the motion of a large number of interfaces connected together, where the physics and chemistry determine the surface dynamics."

The problem with describing foams mathematically has been that the evolution of a bubble cluster a few inches across depends on what's happening in the extremely thin walls of each bubble, which are thinner than a human hair.

"Modeling the vastly different scales in a foam is a challenge, since it is computationally impractical to consider only the smallest space and time scales," Saye said. "Instead, we developed a scale-separated approach that identifies the important physics taking place in each of the distinct scales, which are then coupled together in a consistent manner."

Saye and Sethian discovered a way to treat different aspects of the foam with different sets of equations that worked for clusters of hundreds of bubbles.

One set of equations described the gravitational draining of liquid from the bubble walls, which thin out until they rupture. Another set of equations dealt with the flow of liquid inside the junctions between the bubble membranes.

A third set handled the wobbly rearrangement of bubbles after one pops. Using a fourth set of equations, the mathematicians created a movie of the foam with a sunset reflected in the bubbles.

Solving the full set of equations of motion took five days using supercomputers at the LBNL's National Energy Research Scientific Computing Center (NERSC).

The mathematicians next plan to look at manufacturing processes for small-scale new materials.

"Foams were a good test that all the equations coupled together," Sethian said. "While different problems are going to require different physics, chemistry and models, this sort of approach has applications to a wide range of problems."

]]> Mon, 20 MAY 2013 12:42:42 AEST Paris (AFP) May 14, 2013 - Scientists said Tuesday they have found a way to extract gold from ore using a seemingly unlikely pantry item -- cornstarch.

Traditional leaching employs poisonous cyanide to dissolve and extract the gold locked up in mineral ore -- but the method is polluting and controversial.

Despite being banned in several countries, it is still used to extract more than 80 percent of gold around the world.

Now an international team of scientists said they have accidentally stumbled upon an alternative while doing simple test tube chemistry experiments.

One of the team, Zhichang Liu, mixed a sugar named alpha-cyclodextrin, which is derived from cornstarch, with dissolved gold salt in the hopes of creating some sort of three-dimensional cubic structure.

Though initially disappointed when his experiment failed, Zhichang soon realised he may have discovered something potentially more lucrative, according to the study published in Nature Communications.

"Zhichang stumbled on a piece of magic for isolating gold from anything in a green way," wrote the team.

"We have replaced nasty reagents with a cheap, biologically friendly material derived from starch."

The method could, for example, be used to remove gold from consumer electronic waste -- a potential boon with gold prices having increased four-fold over the last decade.

Several spills have been recorded over the years from mining sites that use cyanide leaching -- putting human lives and the environment at risk.

While Europe allows the use of cyanide in mining, some countries like Germany, Czech Republic and Hungary have outlawed it and in 2010, the European Parliament called for these national bans to extend to the continent as a whole.

"The elimination of cyanide from the gold industry is of the utmost importance environmentally," study leader Fraser Stoddart of Northwestern University's chemistry department said.

The new alternative, alpha-cyclodextrin, is "very cheap and easy to handle", he told AFP.

"The most important thing is the immeasurable environmental benefit for us and future generations."

]]> Mon, 20 MAY 2013 12:42:42 AEST Nottingham UK (SPX) May 13, 2013 - The search for cleaner, low temperature nuclear fuels has produced a shock result for a team of experts at The University of Nottingham.

First they created a stable version of a 'trophy molecule' that has eluded scientists for decades. Now they have discovered that the bonding within this molecule is far different than expected. Remarkably their findings have shown that it behaves in much the same way as its counterparts in the well-known transitional metals such as chromium, molybdenum and tungsten.

The research, done by PhD student David King, which could help in the extraction and separation of the two to three per cent of highly radioactive material in nuclear waste, was led by Professor Stephen Liddle in the School of Chemistry, and has been published in the prestigious academic journal Nature Chemistry.

Professor Liddle said: "The major motivation for doing the first piece of research was to understand the nature of the chemical bonding of uranium. Now we have extended the series to enable meaningful comparisons the 'shock' is that whereas the bonding would be expected to be very different to commonly known and well understood transition metal analogues the bonding is in fact very similar.

This is a real surprise and could have an effect on nuclear clean up because differences in chemical bonding are exploited in the separation processes.

Building on previous advances
Working with experts in the Photon Science Institute at The University of Manchester, their latest discovery builds on their previous advances in this area of chemistry, published in the academic journal Science last year.

With funding from the Royal Society, European Research Council, and Engineering and Physical Sciences Research Council the team first established the method to make the 'title molecule'. For the first time they prepared a terminal uranium nitride compound which was stable at room temperature and could be stored in jars in crystallized or powder form.

Previous attempts to do this required temperatures as low as -268 C - roughly the equivalent temperature of interstellar space - therefore these compounds have, until now, been difficult to work with and manipulate, requiring specialist equipment and techniques.

Exploiting the bonding process
Professor Liddle said: "What the nuclear industry wants to do is minimise the volume of waste by extracting the radioactive elements from spent fuel. This relies on exploiting differences in the bonding, but in some circumstances it may be surprisingly similar and this is going to be important in the amelioration of nuclear waste clean-up and devising new atom-efficient catalytic cycles."

The way atoms behave in uranium bonding is still unclear and there is much debate and great interest in respect to the nature of uranium nitride materials because they have the potential to offer a viable alternative to the mixed oxide nuclear fuels currently used in reactors.

Nitrides exhibit superior high densities, melting points and thermal conductivities and the process this team of researchers has developed could offer a cleaner, low temperature route reducing the amount of impurities which are difficult to remove from the waste produced by current fuels.

]]> Mon, 20 MAY 2013 12:42:42 AEST Subscribe to our daily selection of space, military, environment and energy newsletters responseText http://visitor.constantcontact.com/manage/optin/ea?v=0016gbbKsaiGSpQFojVO8ZoHw%3D%3D