Twinkle, Twinkle, Quantum Dot: New Particles Can Change Colors and Tag Molecules

These tiny plastic nano-particles are stuffed with even tinier bits of electronics called quantum dots. Like little traffic lights, the particles glow brightly in red, yellow, or green, so researchers can easily track molecules under a microscope.

This is the first time anyone has created fluorescent nano-particles that can change colors continuously.

Jessica Winter, assistant professor of chemical and biomolecular engineering and biomedical engineering, and research scientist Gang Ruan describe their patent-pending technology in the online edition of the journalNano Letters.

Researchers routinely tag molecules with fluorescent materials in order to see them under the microscope. Unlike the more common fluorescent molecules, quantum dots shine very brightly, and could illuminate chemical reactions especially well, allowing researchers to see the inner workings of living cells.

A bottleneck to combating major diseases like cancer is the lack of molecular or cellular-level understanding of biological processes, the engineers explained.

"These new nanoparticles could be a great addition to the arsenal of biomedical engineers who are trying to find the roots of diseases," Ruan said.

"We can tailor these particles to tag particular molecules, and use the colors to track processes that we wouldn't otherwise be able to," he continued."Also, this work could be groundbreaking for the field of nanotechnology as a whole, because it solves two seemingly irreconcilable problems with using quantum dots."

Quantum dots are pieces of semiconductor that measure only a few nanometers, or billionths of a meter, across. They are not visible to the naked eye, but when light shines on them, they absorb energy and begin to glow. That's what makes them good tags for molecules.

Due to quantum mechanical effects, quantum dots"twinkle" -- they blink on and off at random moments. When many dots come together, however, their random blinking is less noticeable. So, large clusters of quantum dots appear to glow with a steady light.

Blinking has been a problem for researchers, because it breaks up the trajectory of a moving particle or tagged molecule that they are trying to follow. Yet, blinking is also beneficial, because when dots come together and the blinking disappears, researchers know for certain that tagged molecules have aggregated.

"Blinking is good and bad," Ruan explained."But one day we realized that we could use the 'good' and avoid the 'bad' at the same time, by grouping a few quantum dots of different colors together inside a micelle."

A micelle is a nano-sized spherical container, and while micelles are useful for laboratory experiments, they are easily found in household detergents -- soap forms micelles that capture oils in water. Ruan created micelles using polymers, with different combinations of red and green quantum dots inside them.

In tests, he confirmed that the micelles appeared to glow steadily. Those stuffed with only red quantum dots glowed red, and those stuffed with green glowed green. But those he stuffed with red and green dots alternated from red to green to yellow.

The color change happens when one or another dot blinks inside the micelle. When a red dot blinks off and the green blinks on, the micelle glows green. When the green blinks off and the red blinks on, the micelle glows red. If both are lit up, the micelle glows yellow.

The yellow color is due to our eyes' perception of light. The process is the same as when a red pixel and green pixel appear close together on a television or computer screen: our eyes see yellow.

Nobody can control when color changes happen inside individual micelles. But because the particles glow continuously, researchers can use them to track tagged molecules continuously. They can also monitor color changes to detect when molecules come together.

Winter and Ruan said that the particles could also be used in fluid mechanics research -- specifically, micro-fluidics. Researchers who are developing tiny medical devices with fluid separation channels could use quantum dots to follow the fluid's path.

The same Ohio State research team is also developing magnetic particles to enhance medical imaging of cancer, and it may be possible to combine magnetism with the quantum dot technology for different kinds of imaging. But before the particles would be safe to use in the body, they would have to be made of biocompatible materials. Carbon-based nanomaterials are one possible option.

In the meantime, Winter and Ruan are going to continue developing the color-changing quantum dot particles for studies of cells and molecules under the microscope. They are also going to explore what happens when quantum dots of another color -- for instance, blue -- are added to the mix.

The university will look to license the technology for industry, and Winter and Ruan have created a Web site for the technologies they are developing:http://nanoforneuro.com.

This research was supported by the National Science Foundation, an endowment from the William G. Lowrie family to the Department of Chemical and Biomolecular Engineering, and the Center for Emergent Materials at Ohio State.

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New Blood-Testing Device Can Quickly Spot Cancer Cells, HIV

The microfluidic device, described in the March 17 online edition of the journalSmall, is about the size of a dime, and could also detect viruses such as HIV. It could eventually be developed into low-cost tests for doctors to use in developing countries where expensive diagnostic equipment is hard to come by, says Mehmet Toner, professor of biomedical engineering at Harvard Medical School and a member of the Harvard-MIT Division of Health Sciences and Technology.

Toner built an earlier version of the device four years ago. In that original version, blood taken from a patient flows past tens of thousands of tiny silicon posts coated with antibodies that stick to tumor cells. Any cancer cells that touch the posts become trapped. However, some cells might never encounter the posts at all.

Toner thought if the posts were porous instead of solid, cells could flow right through them, making it more likely they would stick. To achieve that, he enlisted the help of Brian Wardle, an MIT associate professor of aeronautics and astronautics, and an expert in designing nano-engineered advanced composite materials to make stronger aircraft parts.

Out of that collaboration came the new microfluidic device, studded with carbon nanotubes, that collects cancer cells eight times better than the original version.

Captured by nanotubes

Circulating tumor cells (cancer cells that have broken free from the original tumor) are normally very hard to detect, because there are so few of them -- usually only several cells per 1-milliliter sample of blood, which can contain tens of billions of normal blood cells. However, detecting these breakaway cells is an important way to determine whether a cancer has metastasized.

"Of all deaths from cancer, 90 percent are not the result of cancer at the primary site. They're from tumors that spread from the original site," Wardle says.

When designing advanced materials, Wardle often uses carbon nanotubes -- tiny, hollow cylinders whose walls are lattices of carbon atoms. Assemblies of the tubes are highly porous: A forest of carbon nanotubes, which contains 10 billion to 100 billion carbon nanotubes per square centimeter, is less than 1 percent carbon and 99 percent air. This leaves plenty of space for fluid to flow through.

The MIT/Harvard team placed various geometries of carbon nanotube forest into the microfluidic device. As in the original device, the surface of each tube can be decorated with antibodies specific to cancer cells. However, because the fluid can go through the forest geometries as well as around them, there is much greater opportunity for the target cells or particles to get caught.

The researchers can customize the device by attaching different antibodies to the nanotubes' surfaces. Changing the spacing between the nanotube geometric features also allows them to capture different sized objects -- from tumor cells, about a micron in diameter, down to viruses, which are only 40 nm.

The researchers are now beginning to work on tailoring the device for HIV diagnosis. Toner's original cancer-cell-detecting device is now being tested in several hospitals and may be commercially available within the next few years.

Rashid Bashir, director of the Micro and Nanotechnology Laboratory at the University of Illinois at Urbana-Champaign, says that the ability to filter specific particles, cells or viruses from a blood sample so they can be analyzed is a critical step towards creating handheld diagnostic devices.

"Anything you can do to improve capture efficiency, or anything novel you can do to get the particles to interact with a surface more effectively, will help with sample preparation," says Bashir, who was not part of the research team.

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Teaching Robots to Move Like Humans

The research was presented March 7 at the Human-Robot Interaction conference in Lausanne, Switzerland.

"It's important to build robots that meet people's social expectations because we think that will make it easier for people to understand how to approach them and how to interact with them," said Andrea Thomaz, assistant professor in the School of Interactive Computing at Georgia Tech's College of Computing.

Thomaz, along with Ph.D. student Michael Gielniak, conducted a study in which they asked how easily people can recognize what a robot is doing by watching its movements.

"Robot motion is typically characterized by jerky movements, with a lot of stops and starts, unlike human movement which is more fluid and dynamic," said Gielniak."We want humans to interact with robots just as they might interact with other humans, so that it's intuitive."

Using a series of human movements taken in a motion-capture lab, they programmed the robot, Simon, to perform the movements. They also optimized that motion to allow for more joints to move at the same time and for the movements to flow into each other in an attempt to be more human-like. They asked their human subjects to watch Simon and identify the movements he made.

"When the motion was more human-like, human beings were able to watch the motion and perceive what the robot was doing more easily," said Gielniak.

In addition, they tested the algorithm they used to create the optimized motion by asking humans to perform the movements they saw Simon making. The thinking was that if the movement created by the algorithm was indeed more human-like, then the subjects should have an easier time mimicking it. Turns out they did.

"We found that this optimization we do to create more life-like motion allows people to identify the motion more easily and mimic it more exactly," said Thomaz.

The research that Thomaz and Gielniak are doing is part of a theme in getting robots to move more like humans move. In future work, the pair plan on looking at how to get Simon to perform the same movements in various ways.

"So, instead of having the robot move the exact same way every single time you want the robot to perform a similar action like waving, you always want to see a different wave so that people forget that this is a robot they're interacting with," said Gielniak.

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Conch Shell Gives Nano Insights Into Composite Materials

David Williamson and Bill Proud review how these organisms build such tough shells from such a seemingly weak substance. They discover that the key to conch strength lies in the small size of the calcium carbonate crystals from which it is formed by the sea snail. The crystals are below a threshold size known as the Griffith flaw size, any bigger and the crystals would be large enough for cracks to propagate through them under stress, the team explains. This makes the shells tough enough to cope, to some extent, with the crushing jaws of predatory turtles and the vice-like grip of crab claws. Weight for weight the shells are as tough as mild steel.

In the early twentieth century, engineers were preoccupied with the premature failure of materials used in shipping and railways. Concepts such as stress magnification and the propagation of tiny cracks that grow to form big cracks were beginning to be understood. Civil engineer Charles Edward Inglis Inglis devised a mathematical equation to help explain the process. And, in 1920, Alan Arnold Griffith built on the Inglis work to explain for the first time that the reason materials in the real world are not as strong as theoretical calculations would suggest is that the presence of tiny flaws magnify the applied stress in a manner according to the Inglis analysis leading to premature failure.

"Griffith pointed out that the effective strength of technical materials might be increased many tens of times if these flaws could be eliminated," explain Williamson and Proud. Little was known at the time of biomaterials and how their properties might one day copied to create biomimetic materials of much greater strength than their industrial counterparts. Griffith's work has now been used to improve our understanding of conch shells and other biomaterials to allow scientists to produce novel composite biomimetic materials. Research in this area has seen almost exponential growth in the last decade.

The team explains that in the archetypal conch shell material, the queen conch (Strombus gigas) uses a crossed layered, or lamellar, structure. At the smallest length scale the shell is made from tiny crystals of calcium carbonate in the so-called orthorhombic polymorphic form of aragonite. Each single crystal is a mere 60 to 130 nanometres thick and about 100 to 380 nanometres across, although they can be several micrometres long. A nanometre is a billionth of a metre; a micrometre is a thousand times bigger, a millionth of a metre. These dimensions, the Cambridge team explains are below the critical flaw size described by Griffith almost a century ago.

To make a biomimetic material, researchers might first adopt the small crystal size for their composites as well as the crossed layered structure of the conch shell. However, to be truly biomimetic, such materials will also have to incorporate another critical feature of the living material: the ability to self-heal. Attacked by a hungry turtle the shell of a queen conch might be strong enough to deter the predator, but damage will occur, but living tissue can carry out repairs. Materials scientists have discovered that certain polymers can be heat treated so that they undergo self-healing, extended research might allow crystalline composites that mimic conch shell to be made that have the same property.

The team concludes that, it is important to treat these biomaterials as sources of inspiration, rather than prototypes to be replicated in exquisite detail. After all, if nature had access to a modern, high-tech material like the extremely tough ceramic titanium boride used in aluminium smelting equipment and electrical discharge machining, would seashells look the same as they do now?

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Self-Strengthening Nanocomposite Created

Work by the Rice lab of Pulickel Ajayan, professor in mechanical engineering and materials science and of chemistry, shows the potential of stiffening polymer-based nanocomposites with carbon nanotube fillers. The team reported its discovery this month in the journalACS Nano.

The trick, it seems, lies in the complex, dynamic interface between nanostructures and polymers in carefully engineered nanocomposite materials.

Brent Carey, a graduate student in Ajayan's lab, found the interesting property while testing the high-cycle fatigue properties of a composite he made by infiltrating a forest of vertically aligned, multiwalled nanotubes with polydimethylsiloxane (PDMS), an inert, rubbery polymer. To his great surprise, repeatedly loading the material didn't seem to damage it at all. In fact, the stress made it stiffer.

Carey, whose research is sponsored by a NASA fellowship, used dynamic mechanical analysis (DMA) to test their material. He found that after an astounding 3.5 million compressions (five per second) over about a week's time, the stiffness of the composite had increased by 12 percent and showed the potential for even further improvement.

"It took a bit of tweaking to get the instrument to do this," Carey said."DMA generally assumes that your material isn't changing in any permanent way. In the early tests, the software kept telling me, 'I've damaged the sample!' as the stiffness increased. I also had to trick it with an unsolvable program loop to achieve the high number of cycles."

Materials scientists know that metals can strain-harden during repeated deformation, a result of the creation and jamming of defects -- known as dislocations -- in their crystalline lattice. Polymers, which are made of long, repeating chains of atoms, don't behave the same way.

The team is not sure precisely why their synthetic material behaves as it does."We were able to rule out further cross-linking in the polymer as an explanation," Carey said."The data shows that there's very little chemical interaction, if any, between the polymer and the nanotubes, and it seems that this fluid interface is evolving during stressing."

"The use of nanomaterials as a filler increases this interfacial area tremendously for the same amount of filler material added," Ajayan said."Hence, the resulting interfacial effects are amplified as compared with conventional composites.

"For engineered materials, people would love to have a composite like this," he said."This work shows how nanomaterials in composites can be creatively used."

They also found one other truth about this unique phenomenon: Simply compressing the material didn't change its properties; only dynamic stress -- deforming it again and again -- made it stiffer.

Carey drew an analogy between their material and bones."As long as you're regularly stressing a bone in the body, it will remain strong," he said."For example, the bones in the racket arm of a tennis player are denser. Essentially, this is an adaptive effect our body uses to withstand the loads applied to it.

"Our material is similar in the sense that a static load on our composite doesn't cause a change. You have to dynamically stress it in order to improve it."

Cartilage may be a better comparison -- and possibly even a future candidate for nanocomposite replacement."We can envision this response being attractive for developing artificial cartilage that can respond to the forces being applied to it but remains pliable in areas that are not being stressed," Carey said.

Both researchers noted this is the kind of basic research that asks more questions than it answers. While they can easily measure the material's bulk properties, it's an entirely different story to understand how the polymer and nanotubes interact at the nanoscale.

"People have been trying to address the question of how the polymer layer around a nanoparticle behaves," Ajayan said."It's a very complicated problem. But fundamentally, it's important if you're an engineer of nanocomposites.

"From that perspective, I think this is a beautiful result. It tells us that it's feasible to engineer interfaces that make the material do unconventional things."

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Good-Bye, Blind Spot: Always Keeping Robots and Humans in View in Industrial Settings

Move forward, pick up the component, immerse it in the galvanizing bath, move backwards, and deposit the component -- the immersion robot is working continuously to coat metal plates. If an employee is not watchful, collisions can occur. If the person suffers an injury, the process stops. In case the duration of the stop is too long, parts of the robot and components must be completely replaced. Peter Pharow, head of the Data Representation and Interfaces Group at the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau, Germany, is familiar with this problem. Working with several partners from the Thuringia region, the IDMT specialists have developed an intelligent monitoring system for industrial workplaces that makes it possible to predict dangerous situations between man and machine. The roster of partners includes an image processing center, several manufacturers and companies that work with image processing and the use of robots.

The configuration tool"Sim4Save" is part of the monitoring system. Sim4Save is an in-house development of the IDMT and helps furnish the production hall with an optimum number of cameras. To achieve this, they simulate a 3-D model of the production hall displaying the various working areas of interest. The system tells the user how many cameras are required to be able to monitor all safety-relevant areas of the production hall. There are no more blind spots or dark corners."The number of cameras may vary depending on the safety requirements of the company," says Peter Pharow."Not only does our system help set up the cameras optimally and eliminate long trials, but it also aids in targeting their viewing angle."

In addition to the Sim4Save configuration tool, other newly developed components of the intelligent monitoring system include a communication platform, the connected hardware -- robots in particular -- and various pre-processing systems. During routine operation, data from all cameras, ideally also fastened to the gripping arms of the robots, are recorded in real time, analyzed and evaluated."Our specialty is predicting dangerous situations. In an ideal situation the employees can be warned early enough so that there are no accidents," explains Pharow. The scientists use the communication platform they developed, to which configurator data have been transmitted ahead of time. If a collision is imminent during the work process, an alarm will sound, and the system will automatically be slowed down or even stopped. The response time and the reaction itself depend, just like the number of cameras, on the safety requirements of the respective company and the working behavior of the robot. Such an appropriate reaction could range from a simple sound to an immediate total shutdown of the affected machine.

The intelligent monitoring system has been in development for three years, in the"BildRobo" project. The term is composed from the two areas involved: image processing and robotics."Developing a prototype and not a series-ready product was the goal from the beginning. Our next step is to prepare for mass production," explains the IDMT project manager.

In addition to the configuration tool, more projects from the numeric simulation will be introduced at the joint Fraunhofer booth. For example, the"Factory DNA" from the Fraunhofer Institute for Optronics, System Technologies and Image Exploitation IOSB in Karlsruhe: Can an old production facility be used to produce a new product? How many parts will have to be replaced? The Factory DNA answers these questions -- a virtual planning system. Just as with human DNA, the simulation helps interrelate the life cycles of factory objects -- products, production facilities and IT systems. A universal synchronization guarantees consistent data management and continuous data exchange within the IT systems. These data permit evaluation of the extent to which production facilities and IT systems can be used to manufacture new products.

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Materials Identified That May Deliver More 'Bounce'

The alloys could be used in springier blood vessel stents, sensitive microphones, powerful loudspeakers, and components that boost the performance of medical imaging equipment, security systems and clean-burning gasoline and diesel engines.

While these nanostructured metal alloys are not new -- they are used in turbine blades and other parts demanding strength under extreme conditions -- the Rutgers researchers are pioneers at investigating these new properties.

"We have been doing theoretical studies on these materials, and our computer modeling suggests they will be super-responsive," said Armen Khachaturyan, professor of Materials Science and Engineering in the Rutgers School of Engineering. He and postdoctoral researcher Weifeng Rao believe these materials can be a hundred times more responsive than today's materials in the same applications.

Writing in the March 11 issue of the journalPhysical Review Letters, the researchers describe how this class of metals with embedded nanoparticles can be highly elastic, or"springy," and can convert electrical and magnetic energy into movement or vice-versa. Materials that exhibit these properties are known among scientists and engineers as"functional" materials.

One class of functional materials generates an electrical voltage when the material is bent or compressed. Conversely, when the material is exposed to an electric field, it will deform. Known as piezoelectric materials, they are used in ultrasound instruments; audio components such as microphones, speakers and even venerable record players; autofocus motors in some camera lenses; spray nozzles in inkjet printer cartridges; and several types of electronic components.

In another class of functional materials, changes in magnetic fields deform the material and vice-versa. These magnetorestrictive materials have been used in naval sonar systems, pumps, precision optical equipment, medical and industrial ultrasonic devices, and vibration and noise control systems.

The materials that Khachaturyan and Rao are investigating are technically known as"decomposed two-phase nanostructured alloys." They form by cooling metals that were exposed to high temperatures at which the nanosized particles of one crystal structure, or phase, are embedded into another type of phase. The resulting structure makes it possible to deform the metal under an applied stress while allowing the metal to snap back into place when the stress is removed.

These nanostructured alloys might be more effective than traditional metals in applications such blood vessel stents, which have to be flexible but can't lose their"springiness." In the piezoelectric and magnetorestrictive components, the alloy's potential to snap back into shape after deforming -- a property known as non-hysteresis -- could improve energy efficiency over traditional materials that require energy input to restore their original shapes.

In addition to potentially showing responses far greater than traditional materials, the new materials may be tunable; that is, they may exhibit smaller or larger shape changes and output force based on varying mechanical, electrical or magnetic input and the material processing.

The researchers hope to test the results of their computer simulations on actual metals in the near future.

The Rutgers team collaborated with Manfred Wittig, professor of Materials Science and Engineering at the University of Maryland. Their research was funded by the National Science Foundation and the U.S. Department of Energy.

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Shape Memory Polymers Shed Light on How Cells Respond to Physical Environment

Most cell biomechanics research has examined cell behavior on unchanging, flat surfaces."Living cells are remarkably complex, dynamic and versatile systems, but the material substrates currently used to culture them are not," says Henderson."What motivated our work was the need for cell culture technologies that would allow dynamic control of cell-material interactions. We wanted to give a powerful new tool to biologists and bioengineers."

The goal of the current research was to develop a temperature-sensitive shape memory polymer substrate that could be programmed to change shape under cell-compatible conditions. Shape memory polymers (SMPs) are a class of"smart" materials that can switch between two shapes on command, from a fixed (temporary) shape to a pre-determined permanent shape, via a trigger such as a temperature change.

The breakthrough needed to achieve the research goal was made by Kevin Davis, a third-year Ph.D. student in the Henderson lab. Davis was able to develop a SMP with a transition temperature that worked within the limited range required for cells to live. He observed greater than 95 percent cell viability before and after topography and temperature change. This is the first demonstration of this type of cell-compatible, programmable topography change. Davis' and Henderson's work collaboration with Kelly Burke of Case Western Reserve University and Patrick T. Mather, Milton and Ann Stevenson Professor of Biomedical and Chemical Engineering at Syracuse University, is highlighted in the January issue of the journalBiomaterials, the leading journal in biomaterials research.

After confirming that cells remained viable on the substrate, Davis then investigated the changes in cell alignment on the surface that results from topography change. Davis programmed a SMP substrate that transitioned from a micron-scale grooved surface to a smooth surface. When the cells were seeded on the grooved sample at 30ºC, the cells lined up along the grooves of the surface. The substrates were then placed in a 37ºC incubator, which was the transition temperature for the substrate to recover to a smooth surface. Following shape memory recovery, the cells were observed to be randomly oriented on the substrate.

This research project aimed to determine if cells could remain viable with a change in substrate topography and determine whether cells responded to the change. The next phase of this research is to move from a 2D substrate to a 3D substrate and examine cell viability. Additionally, Henderson's team will be looking at what is going on inside the cells as a result of topography changes.

The application of shape memory principles offers potential solutions for current limitations of static substrate research in bioengineering research, such as medical devices and tissue engineering scaffolds."For the first time, we've shown that this general concept can be used successfully with cells, which suggests that it can be extended to a number of biomaterials that could be used for scaffolds and many other applications," says Davis. Since most scaffolding is made out of polymers, Henderson envisions one day using SMPs to create scaffolds that can expand inside the body, allowing for less invasive surgical procedures.

The LCS team of researchers led by Henderson included Davis, Mather, and Burke, a former Ph.D student in Mather's research group.

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Bomb Disposal Robot Getting Ready for Front-Line Action

The organisations have come together to create a lightweight, remote-operated vehicle, or robot, that can be controlled by a wireless device, not unlike a games console, from a distance of several hundred metres.

The innovative robot, which can climb stairs and even open doors, will be used by soldiers on bomb disposal missions in countries such as Afghanistan.

Experts from the Department of Computer& Communications Engineering, based within the university's School of Engineering, are working on the project alongside NIC Instruments Limited of Folkestone, manufacturers of security search and bomb disposal equipment.

Much lighter and more flexible than traditional bomb disposal units, the robot is easier for soldiers to carry and use when out in the field. It has cameras on board, which relay images back to the operator via the hand-held control, and includes a versatile gripper which can carry and manipulate delicate items.

The robot also includes nuclear, biological and chemical weapons sensors.

Measuring just 72cm by 35cm, the robot weighs 48 kilogrammes and can move at speeds of up to eight miles per hour.

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More Efficient Means of Creating, Arranging Carbon Nanofibers Developed

"Carbon nanofibers have a host of potential applications, but their utility is affected by their diameter -- and controlling the diameter of nanofibers has historically been costly and time-consuming," says Dr. Anatoli Melechko, an associate professor of materials science and engineering at NC State and co-author of a paper describing the study.

Specifically, the researchers have shown that nickel nanoparticles coated with a ligand shell can be used to grow carbon nanofibers that are uniform in diameter. Ligands are small organic molecules that have functional groups (parts of the molecule) that bond directly to metals. Nickel nanoparticles are of particular interest because -- at high temperatures -- they can serve as catalysts for growing carbon nanofibers.

"What we learned is that the ligand shell, which is composed of trioctylphosphine, undergoes chemical changes at high temperatures -- gradually transforming into a graphite-like shell," says Dr. Joe Tracy, a co-author of the paper and assistant professor of materials science and engineering at NC State."These 'graphitic' shells prevent the nickel nanoparticles from lumping together at elevated temperatures, which is a problem for high-temperature applications involving nanoparticles."

Using nanoparticles to grow nanofibers is useful, because the fibers tend to have the same diameter as the nanoparticles they are growing from. If you need nanofibers that are 20 nanometers (nm) in diameter, you would simply use nanoparticles that are 20 nm in diameter as your catalyst.

"This is why controlling the diameter of the nanoparticles is important. If they begin to lump together at high temperatures, you end up growing nanofibers of many different, larger sizes," Melechko says."This research gives us a better fundamental understanding of the relationship between nickel nanoparticles, ligands and carbon nanofiber synthesis."

Using nanoparticles to grow nanofibers has another benefit -- it allows you to define where the nanofibers grow and how they are arranged. If you need the nanofibers to grow in a specific pattern, you would arrange the nanoparticles in that pattern before growing the fibers.

The paper was published online March 17 inACS Applied Materials& Interfaces. The paper was co-authored by Melechko, Tracy; NC State Ph.D. students Mehmet Sarac, Aaron Johnston-Peck and Ryan Pearce; NC State undergraduate Robert Wilson; former NC State post-doctoral research associate Dr. Junwei Wang; and Dr. Kate Klein of the National Institute of Standards and Technology.

The research was funded by the National Science Foundation, U.S. Department of Energy, U.S. Department of Education, the Republic of Turkey and Protochips, Inc.

NC State's Department of Materials Science and Engineering is part of the university's College of Engineering.

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Trapping a Rainbow: Researchers Slow Broadband Light Waves With Nanoplasmonic Structures

The idea that a rainbow of broadband light could be slowed down or stopped using plasmonic structures has only recently been predicted in theoretical studies of metamaterials. The Lehigh experiment employed focused ion beams to mill a series of increasingly deeper, nanosized grooves into a thin sheet of silver. By focusing light along this plasmonic structure, this series of grooves or nano-gratings slowed each wavelength of optical light, essentially capturing each individual color of the visible spectrum at different points along the grating. The findings hold promise for improved data storage, optical data processing, solar cells, bio sensors and other technologies.

While the notion of slowing light or trapping a rainbow sounds like ad speak, finding practical ways to control photons -- the particles that makes up light -- could significantly improve the capacity of data storage systems and speed the processing of optical data.

The research required the ability to engineer a metallic surface to produce nanoscale periodic gratings with varying groove depths. This alters the optical properties of the nanopatterned metallic surface, called Surface Dispersion Engineering. The broadband surface light waves are then trapped along this plasmonic metallic surface with each wavelength trapped at a different groove depth, resulting in a trapped rainbow of light.

Through direct optical measurements, the team showed that light of different wavelengths in the 500-700nm region was"trapped" at different positions along the grating, consistent with computer simulations. To prepare the nanopattern gratings required"milling" 150nm wide rectangular grooves every 520nm along the surface of a 300-nm-thick silver sheet. While intrinsic metal loss on the surface of the metal did not permit the complete"stopping" of these plasmons, future research may look into compensating this loss in an effort to stop light altogether.

"Metamaterials, which are man-made materials with feature sizes smaller than the wavelength of light, offer novel applications in nanophotonics, photovoltaic devices, and biosensors on a chip," said Filbert J. Bartoli, principal investigator, professor and chair of the Department of Electrical and Computer Engineering."Creating such nanoscale patterns on a metal film allows us to control and manipulate light propogation. The findings of this paper present an unambiguous experimental demonstration of rainbow trapping in plasmonic nanostructures, and represents an important step in this direction."

"This technology for slowing light at room temperature can be integrated with other materials and components, which could lead to novel platforms for optical circuits. The ability of surface plasmons to concentrate light within nanoscale dimensions makes them very promising for the development of biosensors on chip and the study of nonlinear optical interactions," said Qiaoqiang Gan, who completed this work while a doctoral candidate at Lehigh University, and is now an assistant professor in the Department of Electrical Engineering , State University of New York at Buffalo.

The study was conducted by Bartoli, Qiaoqiang Gan, Yongkang Gao and Yujie J. Ding of the Center for Optical Technologies in the Department of Electrical and Computer Engineering at Lehigh University; and Kyle Wagner and Dmitri V. Vezenov of the Department of Chemistry at Lehigh.

The study was funded by the National Science Foundation. It is published in the current issue of theProceedings of the National Academy of Sciences.

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High-Tech Concrete Technology Has a Famous Past

Almost 1,900 years ago, the Romans built what continues to be the world's largest unreinforced solid concrete dome in the world -- the Pantheon. The secret, probably unknown to the Emperor Hadrian's engineers at the time, was that the lightweight concrete used to build the dome had set and hardened from the inside out. This internal curing process enhanced the material's strength, durability, resistance to cracking, and other properties so that the Pantheon continues to be used for special events to this day.

But it is only within the last decade or so that internally cured concrete has begun to have an impact on modern world infrastructure. Increasingly, internally cured concrete is being used in the construction of bridge decks, pavements, parking structures, water tanks, and railway yards, according to a review of the current status of the new (or old) concrete technology just published by the National Institute of Standards and Technology (NIST).

The virtues of internally cured concrete stem from substituting light-weight, pre-wetted absorbent materials for some of the sand and/or coarse aggregates (stones) that are mixed with cement to make conventional concrete. Dispersed throughout the mixture, the water-filled lightweight aggregates serve as reservoirs that release water on an as-needed basis to nearby hydrating cement particles.

According to one study cited in the review, bridge decks made with internally cured, high-performance concrete were estimated to have a service life of 63 years, as compared with 22 years for conventional concrete and 40 years for high-performance concrete without internal curing.

"As with many new technologies, the path from research to practice has been a slow one, but as of 2010, hundreds of thousands of cubic meters" of the lighter and more durable material have been successfully used in U.S. construction, write the report's co-authors, NIST chemical engineer Dale Bentz and Jason Weiss, Purdue University civil engineering professor.

Compared with conventional varieties, internally cured concrete increases the cost of a project by 10 to 12 percent, Bentz and Weiss estimate on the basis of bridge-building projects in New York and Indiana. The increased front-end cost, they write, must be evaluated against the reduced risk of cracking, better protection against salt damage, and other improved properties that"should contribute to a more durable structure that has a longer life and lower life-cycle costs," they write."Further, this could have substantial benefits in a reduced disruption to the traveling public, generally producing a more sustainable solution."

The 82-page report summarizes the current practice and theory of internal curing, reviews project experiences and material performance in the field, and describes opportunities for research that could lead to enhancements in the material.

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Ferroelectric Materials Discovery Could Lead to Better Memory Chips

In ferroelectric memory the direction of molecules' electrical polarization serves as a 0 or a 1 bit. An electric field is used to flip the polarization, which is how data is stored.

With his colleagues at U-M and collaborators from Cornell University, Penn State University, and University of Wisconsin, Madison, Xiaoqing Pan, a professor in the U-M Department of Materials Science and Engineering, has designed a material system that spontaneously forms small nano-size spirals of the electric polarization at controllable intervals, which could provide natural budding sites for the polarization switching and thus reduce the power needed to flip each bit.

"To change the state of a ferroelectric memory, you have to supply enough electric field to induce a small region to switch the polarization. With our material, such a nucleation process is not necessary," Pan said."The nucleation sites are intrinsically there at the material interfaces."

To make this happen, the engineers layered a ferroelectric material on an insulator whose crystal lattices were closely matched. The polarization causes large electric fields at the ferroelectric surface that are responsible for the spontaneous formation of the budding sites, known as"vortex nanodomains."

The researchers also mapped the material's polarization with atomic resolution, which was a key challenge, given the small scale. They used images from a sub-angstrom resolution transmission electron microscope at Lawrence Berkeley National Laboratory. They also developed image processing software to accomplish this.

"This type of mapping has never been done," Pan said."Using this technique, we've discovered unusual vortex nanodomains in which the electric polarization gradually rotates around the vortices."

This research is funded by the Department of Energy, the National Science Foundation and the U.S. Army Research Office.

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Solar Power Systems Could Lighten the Load for British Soldiers

With the aim of being up to fifty per cent lighter than conventional chemical battery packs used by British infantry, the solar and thermoelectric-powered system could make an important contribution to future military operations.

The project is being developed by the University of Glasgow with Loughborough, Strathclyde, Leeds, Reading and Brunel Universities, with funding from the Engineering and Physical Sciences Research Council (EPSRC). It is also supported by the Defence Science and Technology Laboratory (Dstl).

The system's innovative combination of solar photovoltaic (PV) cells, thermoelectric devices and leading-edge energy storage technology will provide a reliable power supply round-the-clock, just like a normal battery pack. The team is also investigating ways of managing, storing and utilising heat produced by the system.

Because it is much lighter, the system will improve soldiers' mobility. Moreover, by eliminating the need to return to base regularly to recharge batteries, it will increase the potential range and duration of infantry operations. It will also absorb energy across the electromagnetic spectrum, making infantry less liable to detection by night vision equipment that uses infra-red technology, for instance.

Minister for Universities and Science David Willetts said:"The armed forces often need to carry around a huge amount of kit and the means to power it. It's great that specialists from a range of science disciplines are coming together to develop lighter, more reliable technology that will help to make life easier for them in the field."

Although substantial research into solar power for soldiers has already been conducted worldwide, this new UK project differs in its use of thermoelectric devices to complement solar cells, delivering genuine 24/7 power generation capability. The project team is also investigating how both types of device could actually be woven into soldiers' battle dress, which has never been done before.

During the day, the solar cells will produce electricity to power equipment. During the night, the thermoelectric devices will take over and perform the same function. The system will also incorporate advanced energy storage devices to ensure electricity is always available on a continuous basis.

"Infantry need electricity for weapons, radios, global positioning systems and many other vital pieces of equipment," says Professor Duncan Gregory of the University of Glasgow."Batteries can account for over ten per cent of the 45-70kg of equipment that infantry currently carry. By aiding efficiency and comfort, the new system could play a valuable role in ensuring the effectiveness of army operations."

PV cells, thermoelectric devices and advanced energy storage devices are already widely used in a range of applications. A key aim of the project team, however, is to produce robust, hard-wearing designs specifically for military use in tough, hostile conditions.

Because it will harness clean, free energy sources, the new power system will also offer significant environmental advantages compared with the conventional battery packs currently used by the British army.

To tackle the many challenges that the project presents, the team includes specialists from a wide range of disciplines including chemistry, materials science, process engineering, electrical engineering and design. Feedback from serving soldiers will also play a crucial role in optimising the power system for front-line use.

"We aim to produce a prototype system within two years," says Professor Gregory."We also anticipate that the technology that we develop could be adapted for other and very varied uses. One possibility is in niche space applications for powering satellites, another could be to provide means to transport medicines or supplies at cool temperatures in disaster areas or to supply fresh food in difficult economic or climatic conditions."

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New Robot System to Test 10,000 Chemicals for Toxicity

The robot system, which is located at the National Institutes of Health Chemical Genomics Center (NCGC), was purchased as part of the Tox21 collaboration established in 2008 between the U.S. Environmental Protection Agency (EPA), the National Institute of Environmental Health Sciences National Toxicology Program, and NCGC, with the addition of the U.S. Food and Drug Administration (FDA) in 2010. Tox21 merges existing resources -- research, funding and testing tools -- to develop ways to more effectively predict how chemicals will affect human health and the environment.

"Understanding the molecular basis of hazard is fundamental to the protection of people's health and the environment," said Dr. Paul Anastas, assistant administrator of EPA's Office of Research and Development,"Tox21 allows us to obtain deeper understanding and more powerful insights, faster than ever before."

The 10,000 chemicals the robot system will screen include chemicals found in industrial and consumer products, food additives and drugs. Testing results will provide information useful for evaluating if these chemicals have the potential to disrupt human body processes enough to lead to adverse health effects.

"Tox21 has used robots to screen chemicals since 2008, but this new robot system is dedicated to screening a much larger compound library," said NHGRI Director Eric Green, M.D., Ph.D. The director of the NCGC at NHGRI, Christopher Austin, M.D., added"The Tox21 collaboration will transform our understanding of toxicology with the ability to test in a day what would take one year for a person to do by hand."

"The addition of this new robot system will allow the National Toxicology Program to advance its mission of testing chemicals smarter, better, and faster," said Linda Birnbaum, Ph.D., NIEHS and NTP director."We will be able to more quickly provide information about potentially dangerous substances to health and regulatory decision makers, and others, so they can make informed decisions to protect public health."

Tox21 has already screened more than 2,500 chemicals for potential toxicity using robots and other innovative chemical screening technologies. The Tox21 chemical screening technologies were used to screen the different types of oil spill dispersants for potential endocrine activity during the BP oil spill in the Gulf of Mexico last year.

"This partnership builds upon FDA's commitment to developing new methods to evaluate the toxicity of the substances we regulate," said Dr. Janet Woodcock, director of FDA's Center for Drug Evaluation and Research.

EPA contributes to Tox21 through the ToxCast program and by providing chemicals and additional fast, automated tests. ToxCast currently includes 500 chemical screening tests that are assessing more than 1,000 chemicals.

Video of the Tox21 robot is available athttp://www.genome.gov/27543670

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How Do People Respond to Being Touched by a Robotic Nurse?

The research is being presented March 9 at the Human-Robot Interaction conference in Lausanne, Switzerland.

"What we found was that how people perceived the intent of the robot was really important to how they responded. So, even though the robot touched people in the same way, if people thought the robot was doing that to clean them, versus doing that to comfort them, it made a significant difference in the way they responded and whether they found that contact favorable or not," said Charlie Kemp, assistant professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.

In the study, researchers looked at how people responded when a robotic nurse, known as Cody, touched and wiped a person's forearm. Although Cody touched the subjects in exactly the same way, they reacted more positively when they believed Cody intended to clean their arm versus when they believed Cody intended to comfort them.

These results echo similar studies done with nurses.

"There have been studies of nurses and they've looked at how people respond to physical contact with nurses," said Kemp, who is also an adjunct professor in Georgia Tech's College of Computing."And they found that, in general, if people interpreted the touch of the nurse as being instrumental, as being important to the task, then people were OK with it. But if people interpreted the touch as being to provide comfort… people were not so comfortable with that."

In addition, Kemp and his research team tested whether people responded more favorably when the robot verbally indicated that it was about to touch them versus touching them without saying anything.

"The results suggest that people preferred when the robot did not actually give them the warning," said Tiffany Chen, doctoral student at Georgia Tech."We think this might be because they were startled when the robot started speaking, but the results are generally inconclusive."

Since many useful tasks require that a robot touch a person, the team believes that future research should investigate ways to make robot touch more acceptable to people, especially in healthcare. Many important healthcare tasks, such as wound dressing and assisting with hygiene, would require a robotic nurse to touch the patient's body,

"If we want robots to be successful in healthcare, we're going to need to think about how do we make those robots communicate their intention and how do people interpret the intentions of the robot," added Kemp."And I think people haven't been as focused on that until now. Primarily people have been focused on how can we make the robot safe, how can we make it do its task effectively. But that's not going to be enough if we actually want these robots out there helping people in the real world."

In addition to Kemp and Chen, the research group consists of Andrea Thomaz, assistant professor in Georgia Tech's College of Computing, and postdoctoral fellow Chih-Hung Aaron King.

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How Can Robots Get Our Attention?

The research is being presented March 8 at the Human-Robot Interaction conference in Lausanne, Switzerland.

"The primary focus was trying to give Simon, our robot, the ability to understand when a human being seems to be reacting appropriately, or in some sense is interested now in a response with respect to Simon and to be able to do it using a visual medium, a camera," said Aaron Bobick, professor and chair of the School of Interactive Computing in Georgia Tech's College of Computing.

Using the socially expressive robot Simon, from Assistant Professor Andrea Thomaz's Socially Intelligent Machines lab, researchers wanted to see if they could tell when he had successfully attracted the attention of a human who was busily engaged in a task and when he had not.

"Simon would make some form of a gesture, or some form of an action when the user was present, and the computer vision task was to try to determine whether or not you had captured the attention of the human being," said Bobick.

With close to 80 percent accuracy Simon was able to tell, using only his cameras as a guide, whether someone was paying attention to him or ignoring him.

"We would like to bring robots into the human world. That means they have to engage with human beings, and human beings have an expectation of being engaged in a way similar to the way other human beings would engage with them," said Bobick.

"Other human beings understand turn-taking. They understand that if I make some indication, they'll turn and face someone when they want to engage with them and they won't when they don't want to engage with them. In order for these robots to work with us effectively, they have to obey these same kinds of social conventions, which means they have to perceive the same thing humans perceive in determining how to abide by those conventions," he added.

Researchers plan to go further with their investigations into how Simon can read communication cues by studying whether he can tell by a person's gaze whether they are paying attention or using elements of language or other actions.

"Previously people would have pre-defined notions of what the user should do in a particular context and they would look for those," said Bobick."That only works when the person behaves exactly as expected. Our approach, which I think is the most novel element, is to use the user's current behavior as the baseline and observe what changes."

The research team for this study consisted of Bobick, Thomaz, doctoral student Jinhan Lee and undergraduate student Jeffrey Kiser.

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Snails' Complex Muscle Movements, Rather Than Mucous, Key to Locomotion

The main aim of this study, carried out in collaboration with the University of California at San Diego (UCSD) and Stanford University (both in the US) is to characterize some aspects of gastropod (snails and slugs) locomotion to basically respond to one question: To what extent do they depend on the physical properties of their mucus to propel themselves forward? This question is fundamental when applying the studied mechanism to the construction of biomimetic robots."The aim is for the robot to be able to propel itself in any fluid mucus without having to carry its own reserve of mucus along," explained one of the authors of the research study, Javier Rodríguez, Professor at the UC3M Department of Thermal and Fluids Engineering."Bear in mind," he stated,"that snail mucus has a very particular behaviour because it is a specific type of fluid with complex physical characteristics called non-Newtonian fluid."

Until now, it was known that snails and slugs move by propagating their body in a series of muscular wave motions to advance from their tail to their head, but the importance of their mucus in this process was not known. The conclusion obtained by these scientists is that this fluid's properties are not essential for propulsion."Without a doubt, it could have other uses, such as climbing walls, moving upside down, or preserving moisture in the body when on a dry surface, but if we want to construct a robot that emulates a snail, the latter could move over fluid mucus with ordinary properties" pointed out Professor Rodríguez, who has recently published an article on this matter, together with his colleagues from the North American universities, in the scientific review,Journal of Experimental Biology.

To carry out this study, the researchers have characterized the propagation of these muscular waves which occur along the body of gastropods. For this purpose, they place the snails and slugs so that they move on transparent surfaces, illuminating their undersides in different ways so as to record images through digital cameras, subsequently analyzing this data by computer."The ways to illuminate the body vary depending on what is being measured," stated María Vázquez, research fellow from the UC3M Fluid Mechanics Group where she has collaborated in experiments carried out in Spain and in the US."For example," she explained further,"to measure the speed of the wave, we placed a light on the underneath part of the snail, while to measure the vertical deformation of the body we used a low power flat laser (so as not to harm the animal) projected at a given angle." Together, all of these measures have allowed the 3D reconstruction of the snail's underside during propulsion.

Very diverse applications

The most surprising thing about snail movement is summed up very well in a phrase from a biology professor from Stanford University, Mark W. Denny, written in the 1980's:"How can an animal with just one leg walk on glue?" And the mucus is highly adhesive, which offers some advantages such as walking on walls and moving on the ceiling. Furthermore, as anyone who has ever held a snail in their hand can testify, when snails move, they do not use force over specific points, as animals with legs do, but rather they distribute a relatively low force over a relatively large area."What also happens," Professor Rodríguez pointed out,"is that it is difficult to move over glue without exerting quite a bit of force while dragging fluid along." Snails, after millions of years of evolution, have succeeded in being able to move on a highly adhesive surface, avoiding these inconveniences"which is without a doubt of interest and worthy of study," he added

This type of research can help in the design of biomimetic robots that carry out functions which conventional devices cannot do. Some Japanese researchers, for example, propose using the snail propulsion mechanism to move an endoscope though a human body (the trachea, intestines, etc), taking advantage of the mucus film that usually covers these ducts."This mechanism," Javier Rodríguez remarked,"generates a smooth distribution of force instead of supporting itself in concrete points, which would reduce the irritation caused by the movement of an endoscope, in this case."

At the moment, the results published by the UC3M, UCSD and Stanford scientists only deal with the experimental part of study carried out, although they are working on a second article that includes a simple theoretical model which explains these animals' movement. The preliminary results were presented last November at the Annual Conference of The American Physical Society. In addition, these researchers are interested in extending their analysis to situations in which the animal moves up slopes of varying angles.

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NASA Makes Use of Historic Test Site for New Robotic Lander Prototype Tests

This initial test phase, or strapdown testing, allows the engineering team to fully check out the integrated lander prototype before moving to more complex free flight tests. The team secures, or straps down, the prototype during hot fire tests to validate the propulsion system's response to the flight guidance, navigation and control algorithms and flight software prior to autonomous free flight testing.

"Moving the robotic lander tests to the Redstone Test Center facility is a good example of intergovernmental collaboration at its best," said Larry Hill, Robotic Lunar Lander Development Project Manager Test Director, at the Marshall Center."Engineers and

technicians from NASA, the Army and our Huntsville-based support contractor, Teledyne Brown Engineering, have worked tirelessly over the last month to modify the historic test facility formerly used for missile testing to accommodate NASA's lander test in record time, saving NASA time and money."

"Our team has been on a record paced design and development schedule to deliver the robotic lander prototype to the test site," said Julie Bassler, Robotic Lunar Lander Development Project Manager."We have succeeded in designing, building and testing this new lander prototype in a short 17 months with an in-house NASA Marshall team in collaboration with the our partners" -- Johns Hopkins Applied Physics Laboratory of Laurel, Md., and the Von Braun Center for Science and Innovation in Huntsville.

The flight test program includes three phases of testing culminating in free flight testing for periods up to sixty seconds scheduled for summer 2011. The prototype provides a platform to develop and test algorithms, sensors, avionics, software, landing legs, and integrated system elements to support autonomous landings on airless bodies, where aero-braking and parachutes are not options. The test program furthers NASA's capability to conduct science and exploration activities on airless bodies in the solar system.

Development and integration of the lander prototype is a cooperative endeavor led by the Robotic Lunar Lander Development Project at the Marshall Center, Johns Hopkins Applied Physics Laboratory and the Von Braun Center for Science and Innovation, which includes the Science Applications International Corporation, Dynetics Corp., Teledyne Brown Engineering Inc., and Millennium Engineering and Integration Company, all of Huntsville.

The project is partnered with the U.S. Army's Test and Evaluation Command's test center located at Redstone Arsenal. Redstone Test Center is one of six centers under the U.S. Army Test and Evaluation Command and has been a leading test facility for defense systems since the 1950's. Utilizing an historic test site at the Arsenal, the project is leveraging the Redstone Test Center's advanced capability for propulsion testing.

For more photos of the hardware visit:http://www.nasa.gov/roboticlander

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NASA Readies for World's Largest Can Crusher Test

It's similar to what a team of NASA engineers will do to an immense aluminum-lithium rocket fuel tank in late March; their hope is to use data from the test to generate new"shell-buckling design factors" that will enable light-weight, safe and sturdy"skins" for future launch vehicles.

Testing for this innovative study is under way at NASA's Marshall Space Flight Center in Huntsville, Ala., where engineers are supporting the test led by the NASA Engineering and Safety Center, or NESC, based at NASA's Langley Research Center in Hampton, Va.

The aerospace industry's shell buckling knockdown factors are a complex set of engineering data that dates back to Apollo-era studies of rocket structures -- well before modern composite materials, manufacturing processes and advanced computer modeling. The hope is for the new test data to update essential calculations that are typically a significant cost, performance, and safety driver in designing large structures like the main fuel tank of a future heavy-lift launch vehicle.

The large-scale test follows a series of smaller scale tests, all aimed at reducing the time and money spent designing and testing future rockets. And by incorporating more modern, lighter high-tech materials into the design and manufacturing process, rockets will save weight and carry more payload.

This week, technicians moved a 27.5-foot-diameter and 20-foot-tall space shuttle external tank barrel-shaped test article into place at Marshall's Engineering Test Laboratory. Once installed, the section will be sandwiched between two massive loading rings that will press down with almost one-million pounds of force on the central cylindrical test article forcing it to buckle.

"Spacecraft structures, especially fuel tanks, are designed to be as thin as possible, as every pound of vehicle structure sacrifices valuable payload weight and can dramatically increase the cost of flying a rocket," said Mark Hilburger, a senior research engineer in the Structural Mechanics and Concepts Branch at Langley and the principal investigator of the NESC's Shell Buckling Knockdown Factor project."Looking toward future heavy-lifters, our goal is to provide designers greater confidence in how buckling happens in structures so we can develop lighter-weight tanks."

Research to date suggests a potential weight savings of as much as 20 percent.

Leading up to the big crush in late March, the shell buckling team has previously tested four, 8-foot-diameter aluminum-lithium cylinders to failure. In preparation for the upcoming test, hundreds of sensors have been placed on the barrel section to measure strain, local deformations and displacement. In addition, advanced optical measurement techniques will be used to monitor tiny deformations over the entire outer surface of the test article.

"This unique test rig was essential to developing the lightweight space shuttle external tank that is flying today. Our sophisticated testing capability is back in action to better understand design factors for next-generation metallic launch vehicle structures," said Mike Roberts, an engineer in Marshall's Structural Strength Test branch and the center lead for this test activity."Months of preparation for the facility, test article, high-speed cameras and data systems are all in place and ready to support this major test."

The Shell Buckling Knockdown Factor Project is led and funded by the NESC; Marshall is responsible for the test including the engineering, the equipment design, the hardware facilities and safety assurance. Lockheed Martin Space Systems Company fabricated the test article at Marshall's Advance Weld Process Development Facility using state of the art welding and inspection techniques.

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Method Developed to Match Police Sketch, Mug Shot: Algorithms and Software Will Match Sketches With Mugshots in Police Databases

A team led by MSU University Distinguished Professor of Computer Science and Engineering Anil Jain and doctoral student Brendan Klare has developed a set of algorithms and created software that will automatically match hand-drawn facial sketches to mug shots that are stored in law enforcement databases.

Once in use, Klare said, the implications are huge.

"We're dealing with the worst of the worst here," he said."Police sketch artists aren't called in because someone stole a pack of gum. A lot of time is spent generating these facial sketches so it only makes sense that they are matched with the available technology to catch these criminals."

Typically, artists' sketches are drawn by artists from information obtained from a witness. Unfortunately, Klare said,"often the facial sketch is not an accurate depiction of what the person looks like."

There also are few commercial software programs available that produce sketches based on a witness' description. Those programs, however, tend to be less accurate than sketches drawn by a trained forensic artist.

The MSU project is being conducted in the Pattern Recognition and Image Processing lab in the Department of Computer Science and Engineering. It is the first large-scale experiment matching operational forensic sketches with photographs and, so far, results have been promising.

"We improved significantly on one of the top commercial face-recognition systems," Klare said."Using a database of more than 10,000 mug shot photos, 45 percent of the time we had the correct person."

All of the sketches used were from real crimes where the criminal was later identified.

"We don't match them pixel by pixel," said Jain, director of the PRIP lab."We match them up by finding high-level features from both the sketch and the photo; features such as the structural distribution and the shape of the eyes, nose and chin."

This project and its results appear in the March 2011 issue of the journalIEEE Transactions on Pattern Analysis and Machine Intelligence.

The MSU team plans to field test the system in about a year.

The sketches used in this research were provided by forensic artists Lois Gibson and Karen Taylor, and forensic sketch artists working for the Michigan State Police.

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New Technique for Improving Robot Navigation Systems

An autonomous mobile robot is a robot that is able to navigate its environment without colliding or getting lost. Unmanned robots are also able to recover from spatial disorientation. Conducted by Sergio Guadarrama, researcher of the European Centre for Soft Computing, and Antonio Ruiz, assistant professor at the Universidad Politécnica de Madrid's Facultad de Informática, and published in the Information Sciences journal, the research focuses on map building. Map building is one of the skills related to autonomous navigation, where a robot is required to explore an unknown environment (enclosure, plant, buildings, etc.) and draw up a map of the environment. Before it can do this, the robot has to use its sensors to perceive obstacles.

The main sensor types used for autonomous navigation are vision and range sensors. Although vision sensors can capture much more information from the environment, this research used range, specifically ultrasonic, sensors, which are less accurate, to demonstrate that the model builds accurate maps from few and imprecise input data.

Once it has captured the ranges, the robot has to map these distances to obstacles on the map. Point clouds are used to draw the map, as the imprecision of the range data rules out the use of straight lines or even isolated points. Even so, the resulting map is by no means an architectural blueprint of the site, because not even the robot's location is precisely known, and there is no guarantee that each point cloud is correctly positioned. In actual fact, one and the same obstacle can be viewed properly from one robot position, but not from another. This can produce contradictory information -obstacle and no obstacle- about the same area of the map under construction. Which of the two interpretations is correct?

Exploring unknown spaces

The solution is based on linguistic descriptions of the antonyms"vacant" and"occupied" and inspired by computing with words and the computational theory of perceptions, two theories proposed by L.A. Zadeh of the University of California at Berkeley. Whereas other published research views obstacles and empty spaces as complementary concepts, this research assumes that, rather than being complements, obstacles and vacant spaces are a pair of opposites.

For example, we can infer that an occupied space is not vacant, but we cannot infer that an unoccupied space is empty. This space could be unknown or ambiguous, because the robot has limited information about its environment. Also the contradictions between"vacant" and"occupied" are also explicitly represented.

This way, the robot is able to make a distinction between two types of unknown spaces: spaces that are unknown because information is contradictory and spaces that are unknown because they are unexplored. This would lead the robot to navigate with caution through the contradictory spaces and explore the unexplored spaces. The map is constructed using linguistic rules, such as"If the measured distance is short, then assign a high confidence level to the measurement" or"If an obstacle has been seen several times, then increase the confidence in its presence," where"short,""high" and"several" are fuzzy sets, subject to fuzzy sets theory. Contradictions are resolved by a greater reliance on shorter ranges and combining multiple measures.

Compared with the results of other methods, the outcomes show that the maps built using this technique better capture the shape of walls and open spaces, and contain fewer errors from incorrect sensor data. This opens opportunities for improving the current autonomous navigation systems for robots.

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New Kind of Optical Fiber Developed: Made With a Core of Zinc Selenide

The team's research will be published in the journalAdvanced Materials.

"It has become almost a cliche to say that optical fibers are the cornerstone of the modern information age," said Badding."These long, thin fibers, which are three times as thick as a human hair, can transmit over a terabyte -- the equivalent of 250 DVDs -- of information per second. Still, there always are ways to improve on existing technology." Badding explained that optical-fiber technology always has been limited by the use of a glass core."Glass has a haphazard arrangement of atoms," Badding said."In contrast, a crystalline substance like zinc selenide is highly ordered. That order allows light to be transported over longer wavelengths, specifically those in the mid-infrared."

Unlike silica glass, which traditionally is used in optical fibers, zinc selenide is a compound semiconductor."We've known for a long time that zinc selenide is a useful compound, capable of manipulating light in ways that silica can't," Badding said."The trick was to get this compound into a fiber structure, something that had never been done before." Using an innovative high-pressure chemical-deposition technique developed by Justin Sparks, a graduate student in the Department of Chemistry, Badding and his team deposited zinc selenide waveguiding cores inside of silica glass capillaries to form the new class of optical fibers."The high-pressure deposition is unique in allowing formation of such long, thin, zinc selenide fiber cores in a very confined space," Badding said.

The scientists found that the optical fibers made of zinc selenide could be useful in two ways. First, they observed that the new fibers were more efficient at converting light from one color to another."When traditional optical fibers are used for signs, displays, and art, it's not always possible to get the colors you want," Badding explained."Zinc selenide, using a process called nonlinear frequency conversion, is more capable of changing colors."

Second, as Badding and his team expected, they found that the new class of fiber provided more versatility not just in the visible spectrum, but also in the infrared -- electromagnetic radiation with wavelengths longer than those of visible light. Existing optical-fiber technology is inefficient at transmitting infrared light. However, the zinc selenide optical fibers that Badding's team developed are able to transmit the longer wavelengths of infrared light."Exploiting these wavelengths is exciting because it represents a step toward making fibers that can serve as infrared lasers," Badding explained."For example, the military currently uses laser-radar technology that can handle the near-infrared, or 2 to 2.5-micron range. A device capable of handling the mid-infrared, or over 5-micron range would be more accurate. The fibers we created can transmit wavelengths of up to 15 microns."

Badding also explained that the detection of pollutants and environmental toxins could be yet another application of better laser-radar technology capable of interacting with light of longer wavelengths."Different molecules absorb light of different wavelengths; for example, water absorbs, or stops, light at the wavelengths of 2.6 microns," Badding said."But the molecules of certain pollutants or other toxic substances may absorb light of much longer wavelengths. If we can transport light over longer wavelengths through the atmosphere, we can see what substances are out there much more clearly." In addition, Badding mentioned that zinc selenide optical fibers also may open new avenues of research that could improve laser-assisted surgical techniques, such as corrective eye surgery.

In addition to Badding and Sparks, other researchers who contributed to this study include Rongrui He of Penn State's Department of Chemistry and the Materials Research Institute; Mahesh Krishnamurthi and Venkatraman Gopalan of Penn State's Department of Materials Science and Engineering and the Materials Research Institute; and Pier J.A. Sazio, Anna C. Peacock, and Noel Healy of the Optoelectronics Research Centre at the University of Southampton. Support for this research was provided by the Engineering and Physical Sciences Research Council, the National Science Foundation, and the Penn State University Materials Research Science and Engineering Center.

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Silk Moth's Antenna Inspires New Nanotech Tool With Applications in Alzheimer's Research

A paper on the work is newly published online inNature Nanotechnology. This project is headed by Michael Mayer, an associate professor in the U-M departments of Biomedical Engineering and Chemical Engineering. Also collaborating are Jerry Yang, an associate professor at the University of California, San Diego and Jiali Li, an associate professor at the University of Arkansas.

Nanopores -- essentially holes drilled in a silicon chip -- are miniscule measurement devices that enable the study of single molecules or proteins. Even today's best nanopores clog easily, so the technology hasn't been widely adopted in the lab. Improved versions are expected to be major boons for faster, cheaper DNA sequencing and protein analysis.

The team engineered an oily coating that traps and smoothly transports molecules of interest through nanopores. The coating also allows researchers to adjust the size of the pore with close-to-atomic precision.

"What this gives us is an improved tool to characterize biomolecules," Mayer said."It allows us to gain understanding about their size, charge, shape, concentration and the speed at which they assemble. This could help us possibly diagnose and understand what is going wrong in a category of neurodegenerative disease that includes Parkinson's, Huntington's and Alzheimer's."

Mayer's"fluid lipid bilayer" resembles a coating on the male silk moth's antenna that helps it smell nearby female moths. The coating catches pheromone molecules in the air and carries them through nanotunnels in the exoskeleton to nerve cells that send a message to the bug's brain.

"These pheromones are lipophilic. They like to bind to lipids, or fat-like materials. So they get trapped and concentrated on the surface of this lipid layer in the silk moth. The layer greases the movement of the pheromones to the place where they need to be. Our new coating serves the same purpose," Mayer said.

One of Mayer's main research tracks is to study proteins called amyloid-beta peptides that are thought to coagulate into fibers that affect the brain in Alzheimer's. He is interested in studying the size and shape of these fibers and how they form.

"Existing techniques don't allow you to monitor the process very well. We wanted to see the clumping of these peptides using nanopores, but every time we tried it, the pores clogged up," Mayer said."Then we made this coating, and now our idea works."

To use nanopores in experiments, researchers position the pore-pricked chip between two chambers of saltwater. They drop the molecules of interest into one of the chambers and send an electric current through the pore. As each molecule or protein passes through the pore, it changes the pore's electrical resistance. The amount of change observed tells the researchers valuable information about the molecule's size, electrical charge and shape.

Due to their small footprint and low power requirements, nanopores could also be used to detect biological warfare agents.

A research highlight on this work will appear in an upcoming edition of Nature. The paper is titled"Controlling protein translocation through nanopores with bio-inspired fluid walls."

This research is funded by the National Science Foundation, the National Institutes of Health, the Alzheimer's Disease Research Center, the Alzheimer's Association and the National Human Genome Research Institute. The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.

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