New approach to overcome key hurdle for next-generation superconductors

ScienceDaily (Oct. 27, 2011) — Researchers from North Carolina State University have developed a new computational approach to improve the utility of superconductive materials for specific design applications -- and have used the approach to solve a key research obstacle for the next-generation superconductor material yttrium barium copper oxide (YBCO).

A superconductor is a material that can carry electricity without any loss -- none of the energy is dissipated as heat, for example. Superconductive materials are currently used in medical MRI technology, and are expected to play a prominent role in emerging power technologies, such as energy storage or high-efficiency wind turbines.

One problem facing systems engineers who want to design technologies that use superconductive materials is that they are required to design products based on the properties of existing materials. But NC State researchers are proposing an approach that would allow product designers to interact directly with the industry that creates superconductive materials -- such as wires -- to create superconductors that more precisely match the needs of the finished product.

"We are introducing the idea that wire manufacturers work with systems engineers earlier in the process, utilizing computer models to create better materials more quickly," says Dr. Justin Schwartz, lead author of a paper on the process and Kobe Steel Distinguished Professor and head of NC State's Department of Materials Science and Engineering. "This approach moves us closer to the ideal of having materials engineering become part of the product design process."

To demonstrate the utility of the process, researchers tackled a problem facing next-generation YBCO superconductors. YBCO conductors are promising because they are very strong and have a high superconducting current density -- meaning they can handle a large amount of electricity. But there are obstacles to their widespread use.

One of these key obstacles is how to handle "quench." Quench is when a superconductor suddenly loses its superconductivity. Superconductors are used to store large amounts of electricity in a magnetic field -- but a quench unleashes all of that stored energy. If the energy isn't managed properly, it will destroy the system -- which can be extremely expensive. "Basically, the better a material is as a superconductor, the more electricity it can handle, so it has a higher energy density, and that makes quench protection more important, because the material may release more energy when quenched," Schwartz says.

To address the problem, researchers explored seven different variables to determine how best to design YBCO conductors in order to optimize performance and minimize quench risk. For example, does increasing the thickness of the YBCO increase or decrease quench risk? As it turns out, it actually decreases quench risk. A number of other variables come into play as well, but the new approach was effective in helping researchers identify meaningful ways of addressing quench risk.

"The insight we've gained into YBCO quench behavior, and our new process for designing better materials, will likely accelerate the use of YBCO in areas ranging from new power applications to medical technologies -- or even the next iteration of particle accelerators," Schwartz says.

"This process is of particular interest given the White House's Materials Genome Initiative," Schwartz says. "The focus of that initiative is to expedite the process that translates new discoveries in materials science into commercial products -- and I think our process is an important step in that direction."

The paper was co-authored by Dr. Wan Kan Chan, a research associate at NC State. The paper is available online from IEEE Transactions on Applied Superconductivity. The research was funded by the Air Force Research Laboratory.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by North Carolina State University.

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

Journal Reference:

Wan Kan Chan, Justin Schwartz. Three-Dimensional Micrometer-Scale Modeling of Quenching in High-Aspect-Ratio YBa2Cu3O7-d Coated Conductor Tapes -- Part II: Influence of Geometric and Material Properties and Implications for Conductor Engineering and Magnet Design. IEEE Transactions on Applied Superconductivity, 2011; DOI: 10.1109/TASC.2011.2169670

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Chiral metal surfaces may help to manufacture pharmaceuticals; Novel approach could be used in pharmaceutical drug synthesis

ScienceDaily (Oct. 26, 2011) — New research shows how metal surfaces that lack mirror symmetry could provide a novel approach towards manufacturing pharmaceuticals.

These 'intrinsically chiral' metal surfaces offer potential new ways to control chiral chemistry, pointing to the intriguing possibility of using heterogeneous catalysis in drug synthesis. Such surfaces could also become the basis of new biosensor technologies.

A chiral object, such as your hand, is one that cannot be superposed on its mirror image. Chirality is fundamental in biochemistry. The building blocks of life -- amino acids and sugars -- are chiral molecules: their molecular structures can exist in either "left-handed" or "right-handed" forms (or "enantiomers").

A living organism may respond differently to the two enantiomers of a chiral substance. This is crucially important in the case of pharmaceutical drugs, where the therapeutic effect is often tied strongly to just one enantiomer of the drug molecule. Controlling chirality is therefore vital in pharmaceutical synthesis.

Research into controlling chiral synthesis focuses mainly on using homogeneous catalysts, where the catalyst is in the same phase as the reactants and products, such as a liquid added to a liquid-phase reaction. However, this poses significant practical challenges in recovering the valuable catalyst material from the mixture. To avoid this problem, an attractive alternative would be heterogeneous catalysis over a solid surface -- the type of catalysis used in catalytic converters in car exhaust systems, as well as in industrial Haber-Bosch synthesis of ammonia and Fischer-Tropsch synthesis of synthetic fuel, for example. The question then is how to achieve enantiomer-specific effects at a surface.

To help answer this question, scientists at the University of Cambridge have been probing the spontaneous self-organization of a simple chiral amino acid, alanine, into regular molecular arrays on copper single-crystal surfaces. Thanks to a powerful scanning tunnelling microscope, capable of resolving individual atoms and molecules, their work is revealing the various manifestations of chirality that occur, giving important clues to how they arise, and how they might be controlled and exploited.

Dr Stephen Driver, of the Department of Chemistry at the University of Cambridge, who led the experimental work, said: "We set out to investigate two distinct scenarios. In one scenario, the surface is non-chiral, so any chirality that we see can only arise from the chirality of the alanine molecule. In the other scenario, we move to a surface that is intrinsically chiral. Now the question becomes: do the two enantiomers of alanine behave differently on this chiral surface?"

On the non-chiral surface, the researchers found that alanine can self-organise into either of two patterns. In one of these, the self-organisation is driven by hydrogen bonding between the molecules, while the chiral centre has no discernable impact on the regular array. In the other structure, a network of long-range chiral boundaries punctuates the array, and the boundary chirality switches with molecular chirality.

Driver explained: "The implication is that the chiral centre is having a direct influence on the packing of two alanine neighbours at the boundary, and that the chirality of this pair propagates to the next pair and the next and so on, so that the chiral boundary is built up over a long range."

The chiral surface is created simply by choosing a surface orientation that lies away from any of the bulk mirror symmetry planes of the metal crystal. When the researchers added alanine, they found that the surface changes its local orientation, forming nanometre-scale facets. The two enantiomers of alanine self-organise into different chiral patterns: a strong, enantiomer-specific structural effect. This "proof of principle" could potentially be exploited in chiral recognition, in chiral synthesis (forming a chiral product from non-chiral reactants), and in chiral separations.

Driver added: "It looks like alanine can shape a comfortable, chiral bonding site for itself. The copper surface has the flexibility to adapt itself to the shape of the alanine molecule, and this shape is different for the two different molecular enantiomers."

The results imply that certain surface orientations will form stable, ordered structures with one molecular enantiomer but not the other: exactly the right conditions to promote chiral chemical effects.

Professor Sir David King, former Chief Scientific Advisor to the UK Government and current Director of the Smith School of Enterprise and the Environment at Oxford, brought together the team carrying out this research. "These results are very exciting," said King. "Tailoring the right surface to the right molecule should lead to strong enantiospecific effects. We see a real basis here for a breakthrough technology in the pharmaceuticals sector. It's something that pharma companies should be taking a close interest in."

The Cambridge team's findings are published in Topics in Catalysis.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons license.

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

Journal Reference:

Marian L. Clegg, Leonardo Morales de la Garza, Sofia Karakatsani, David A. King, Stephen M. Driver. Chirality in Amino Acid Overlayers on Cu Surfaces. Topics in Catalysis, 2011; DOI: 10.1007/s11244-011-9758-y

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Better glasses-free 3-D: Mew approach to make 3-D illusions more realistic

ScienceDaily (May 5, 2011) — Nintendo's 3DS portable gaming system, the first commercial device with a glasses-free 3-D screen, has been available in the United States for barely a month, and it's already sold more than a million units. Its three-hour battery life, however, is less than half that of its predecessor, the 2-D DS device.

Researchers at MIT's Media Lab have developed a fundamentally new approach to glasses-free 3-D, called HR3D, which they say could double the battery life of devices like the 3DS without compromising screen brightness or resolution. Among other advantages, the technique could also expand the viewing angle of a 3-D screen, making it practical for larger devices with multiple users, and it would maintain the 3-D effect even when the screen is rotated -- something that happens routinely with handheld devices.

According to Doug Lanman, a postdoc in Associate Professor Ramesh Raskar's Camera Culture Group at the Media Lab, the 3DS relies on a century-old technology known as a parallax barrier. Like most 3-D technologies, this one requires two versions of the same image, one tailored to the left eye and one to the right. The two images are sliced into vertical segments and interleaved on a single surface.

By itself, the composite image looks like an incoherent jumble. But if you place a screen with vertical slits in it -- the parallax barrier -- just in front of the image and stand the right distance away, a 3-D image pops out. The opaque sections of the screen shield the parts of the image intended for the right eye from the left eye, and vice versa, but the slits allow each eye to see the segments intended for it.

The 3DS screen consists of two parallel liquid-crystal displays (LCDs) a small distance apart. When the device is operating in 3-D mode, the front display serves as the parallax barrier, depicting a series of opaque vertical stripes. Since the stripes block half the light coming from the screen, the device's backlight has to be twice as bright, which drains the battery twice as quickly. Moreover, because the spacing of the stripes is calibrated to the horizontal separation of human eyes, if the screen is tilted, the 3-D illusion disappears.

All the angles

Raskar and Lanman, along with postdoc Yun Hee Kim and graduate student Matthew Hirsch, decided to rethink glasses-free 3-D from the ground up. In the real world, as a viewer moves around an object, his or her perspective on it changes constantly. A convincing simulation of 3-D visual experience, Lanman argues, might require a display that offers a dozen different perspectives as the viewer moves from right to left.

But with parallax-barrier 3-D, each new perspective further restricts light emission. Adding multiple perspectives in the vertical direction as well as the horizontal would require a parallax barrier with horizontal as well as vertical bands. For a display with enough different views, the parallax barrier ends up looking like an opaque sheet with pinholes poked in it.

Like the 3DS, the MIT researchers' HR3D system uses two layers of liquid-crystal displays. But instead of displaying vertical bands, as the 3DS does, or pinholes, as a multiperspective parallax-barrier system would, the top LCD displays a pattern customized to the image beneath it.

Going into the project, the researchers had no idea what the customized pattern would look like. But once they'd done the math, they found that the ideal pattern ends up looking a lot like the source image. Instead of consisting of a few big, vertical slits, the parallax barrier consists of thousands of tiny slits, whose orientations follow the contours of the objects in the image.

Number crunching

Because the slits are oriented in so many different directions, the 3-D illusion is consistent no matter whether the image is upright or rotated 90 degrees. Adding more perspectives changes the pattern of the slits, but they allow just as much light to pass.

If a device like the 3DS used HR3D, Lanman says, its battery life would be longer, because the parallax barrier would block less light. The 3-D effect would also be consistent no matter the device's orientation: applications could actually take advantage of screen rotation, particularly in devices that have built-in motion sensors. "But the real win," Lanman says, "comes with full parallax motion" -- that is, a display that shows multiple perspectives in both the horizontal and vertical directions.

"The great thing about Ramesh's group is that they think of things that no one else has thought of and then demonstrate that they can actually be done," says Neil Dodgson, professor of graphics and imaging at the University of Cambridge in England, who was one of the reviewers of the paper when it was accepted last year to the SIGGRAPH Asia graphics conference. "It's quite a clever idea they've got here."

Dodgson points out, however, that HR3D is very computationally intensive. "If you're saving battery power because you've got this extra brightness, but you're actually using all that battery power to do the computation, then you're not saving anything," he says.

While Lanman acknowledges that the algorithm for calculating the barrier pattern that he and his colleagues described in the SIGGRAPH Asia paper is computationally complex, he believes that it can be refined so that "it requires far less computation." He also points out that special-purpose chips designed specifically to run a refined version of the algorithm would consume much less power than a general-purpose processor performing the same computations.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by Larry Hardesty, MIT News Office.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Better glasses-free 3-D: Mew approach to make 3-D illusions more realistic

ScienceDaily (May 5, 2011) — Nintendo's 3DS portable gaming system, the first commercial device with a glasses-free 3-D screen, has been available in the United States for barely a month, and it's already sold more than a million units. Its three-hour battery life, however, is less than half that of its predecessor, the 2-D DS device.

Researchers at MIT's Media Lab have developed a fundamentally new approach to glasses-free 3-D, called HR3D, which they say could double the battery life of devices like the 3DS without compromising screen brightness or resolution. Among other advantages, the technique could also expand the viewing angle of a 3-D screen, making it practical for larger devices with multiple users, and it would maintain the 3-D effect even when the screen is rotated -- something that happens routinely with handheld devices.

According to Doug Lanman, a postdoc in Associate Professor Ramesh Raskar's Camera Culture Group at the Media Lab, the 3DS relies on a century-old technology known as a parallax barrier. Like most 3-D technologies, this one requires two versions of the same image, one tailored to the left eye and one to the right. The two images are sliced into vertical segments and interleaved on a single surface.

By itself, the composite image looks like an incoherent jumble. But if you place a screen with vertical slits in it -- the parallax barrier -- just in front of the image and stand the right distance away, a 3-D image pops out. The opaque sections of the screen shield the parts of the image intended for the right eye from the left eye, and vice versa, but the slits allow each eye to see the segments intended for it.

The 3DS screen consists of two parallel liquid-crystal displays (LCDs) a small distance apart. When the device is operating in 3-D mode, the front display serves as the parallax barrier, depicting a series of opaque vertical stripes. Since the stripes block half the light coming from the screen, the device's backlight has to be twice as bright, which drains the battery twice as quickly. Moreover, because the spacing of the stripes is calibrated to the horizontal separation of human eyes, if the screen is tilted, the 3-D illusion disappears.

All the angles

Raskar and Lanman, along with postdoc Yun Hee Kim and graduate student Matthew Hirsch, decided to rethink glasses-free 3-D from the ground up. In the real world, as a viewer moves around an object, his or her perspective on it changes constantly. A convincing simulation of 3-D visual experience, Lanman argues, might require a display that offers a dozen different perspectives as the viewer moves from right to left.

But with parallax-barrier 3-D, each new perspective further restricts light emission. Adding multiple perspectives in the vertical direction as well as the horizontal would require a parallax barrier with horizontal as well as vertical bands. For a display with enough different views, the parallax barrier ends up looking like an opaque sheet with pinholes poked in it.

Like the 3DS, the MIT researchers' HR3D system uses two layers of liquid-crystal displays. But instead of displaying vertical bands, as the 3DS does, or pinholes, as a multiperspective parallax-barrier system would, the top LCD displays a pattern customized to the image beneath it.

Going into the project, the researchers had no idea what the customized pattern would look like. But once they'd done the math, they found that the ideal pattern ends up looking a lot like the source image. Instead of consisting of a few big, vertical slits, the parallax barrier consists of thousands of tiny slits, whose orientations follow the contours of the objects in the image.

Number crunching

Because the slits are oriented in so many different directions, the 3-D illusion is consistent no matter whether the image is upright or rotated 90 degrees. Adding more perspectives changes the pattern of the slits, but they allow just as much light to pass.

If a device like the 3DS used HR3D, Lanman says, its battery life would be longer, because the parallax barrier would block less light. The 3-D effect would also be consistent no matter the device's orientation: applications could actually take advantage of screen rotation, particularly in devices that have built-in motion sensors. "But the real win," Lanman says, "comes with full parallax motion" -- that is, a display that shows multiple perspectives in both the horizontal and vertical directions.

"The great thing about Ramesh's group is that they think of things that no one else has thought of and then demonstrate that they can actually be done," says Neil Dodgson, professor of graphics and imaging at the University of Cambridge in England, who was one of the reviewers of the paper when it was accepted last year to the SIGGRAPH Asia graphics conference. "It's quite a clever idea they've got here."

Dodgson points out, however, that HR3D is very computationally intensive. "If you're saving battery power because you've got this extra brightness, but you're actually using all that battery power to do the computation, then you're not saving anything," he says.

While Lanman acknowledges that the algorithm for calculating the barrier pattern that he and his colleagues described in the SIGGRAPH Asia paper is computationally complex, he believes that it can be refined so that "it requires far less computation." He also points out that special-purpose chips designed specifically to run a refined version of the algorithm would consume much less power than a general-purpose processor performing the same computations.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by Larry Hardesty, MIT News Office.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here