June 3, 2009, 5:01 AM CT

Memory with a twist

Electronic memory chips may soon gain the ability to bend and twist as a result of work by engineers at the National Institute of Standards and Technology (NIST). As published in the July 2009 issue of IEEE Electron Device Letters,* the engineers have found a way to build a flexible memory component out of inexpensive, readily available materials.

Though still not ready for the marketplace, the new device is promising not only because of its potential applications in medicine and other fields, but because it also appears to possess the characteristics of a memristor, a fundamentally new component for electronic circuits that industry researchers developed in 2008.** NIST has filed for a patent on the flexible memory device (application #12/341.059).

Electronic components that can flex without breaking are coveted by portable device manufacturers for a number of reasonsand not just because people have a tendency to drop their mp3 players. Small medical sensors that can be worn on the skin to monitor vital signs such as heart rate or blood sugar could benefit patients with conditions that require constant maintenance, for example. Though some flexible components exist, creating flexible memory has been a technical barrier, as per NIST researchers.

Hunting for a solution, the scientists took polymer sheetsthe sort that transparencies for overhead projectors are made fromand experimented with depositing a thin film of titanium dioxide, an ingredient in sunscreen, on their surfaces. Instead of using expensive equipment to deposit the titanium dioxide as is traditionally done, the material was deposited by a sol gel process, which consists of spinning the material in liquid form and letting it set, like making gelatin. By adding electrical contacts, the team created a flexible memory switch that operates on less than 10 volts, maintains its memory when power is lost, and still functions after being flexed more than 4,000 times......... Posted by: Kevin      Read more         Source

June 1, 2009, 6:56 PM CT

Nanosecond pressure jump

A new method to induce protein folding by taking the pressure off of proteins is up to 100 times faster than prior methods, and could help guide more accurate computer simulations for how complex proteins fold, as per research by a team of University of Illinois researchers accepted for publication in the journal Nature Methods and posted on the journal's Web site May 31.

Martin Gruebele, the James R. Eiszner Professor of Chemistry at the U. of I. and corresponding author of the paper, says that prodding proteins to fold by suddenly removing high pressure (a technique also known as "pressure jumping") through electrical bursting makes for a "kindler, gentler way" of inducing proteins to fold.

"When you're increasing the pressure on something, you're squeezing the atoms and making them come closer to one another," Gruebele said, "but you're not necessarily causing the very complicated changes to the microscopic motion that occur when you change the temperature. Pressure is a simpler variable than temperature".

In order to carry out their biomolecular functions, proteins fold from a chaotic, random coil that looks like spaghetti strands floating in boiling water to their native state as an orderly, well-defined but compact structure.

From the point-of-view of the protein, Gruebele said, pressurizing it to about 2,500 atmospheres is much less disruptive than, say, cranking up the temperature by 30 degrees......... Posted by: Kevin      Read more         Source

May 24, 2009, 8:57 PM CT

Multiferroics

Multiferroics are materials in which unique combinations of electric and magnetic properties can simultaneously coexist. They are potential cornerstones in future magnetic data storage and spintronic devices provided a simple and fast way can be found to turn their electric and magnetic properties on and off. In a promising new development, scientists with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) working with a prototypical multiferroic have successfully demonstrated just such a switch -- electric fields.

"Using electric fields, we have been able to create, erase and invert pn junctions in a calcium-doped bismuth ferrite film," said Ramamoorthy Ramesh of Berkeley Lab's Materials Sciences Division (MSD), who led this research.

"Through the combination of electronic conduction with the electric and magnetic properties already present in the multiferroic bismuth ferrite, our demonstration opens the door to merging magnetoelectrics and magnetoelectronics at room temperature".

Ramesh, who is also a professor in the Department of Materials Science and Engineering and the Department of Physics at UC Berkeley, has published a paper on this research that is now available in the on-line edition of the journal Nature Materials The paper is titled: "Electric modulation of conduction in multiferroic......... Posted by: Kevin      Read more         Source

May 18, 2009, 5:38 AM CT

Detecting single atoms

Researchers have devised a new technique for real-time detection of freely moving individual neutral atoms that is more than 99.7% accurate and sensitive enough to discern the arrival of a single atom in less than one-millionth of a second, about 20 times faster than the best prior methods.

The system, described in Advance Online Publication at the Nature Physics web site by scientists at the Joint Quantum Institute (JQI) in College Park, MD, and the Universidad de Concepcin in Chile, employs a novel means of altering the polarization of laser light trapped between two highly-reflective mirrors, in effect letting the researchers "see" atoms passing through by the individual photons that they scatter.

The ability to detect single atoms and molecules is essential to progress in a number of areas, including quantum information research, chemical detection and biochemical analysis.

"Existing protocols have been too slow to detect moving atoms, making it difficult to do something to them before they are gone. Our work relaxes that speed constraint," says coauthor David Norris of JQI. "Moreover, it is hard to distinguish between a genuine detection and a random 'false positive' without collecting data over a large period of time. Our system both filters the signal and reduces the detection time"......... Posted by: Kevin      Read more         Source

May 14, 2009, 9:36 PM CT

Shift in Simulation Superiority

Science and engineering are advancing rapidly in part due to ever more powerful computer simulations, yet the most advanced supercomputers require programming skills that all too few U.S. scientists possess. At the same time, affordable computers and committed national programs outside the U.S. are eroding American competitiveness in number of simulation-driven fields.

These are some of the key findings in the International Evaluation of Research and Development in Simulation-Based Engineering and Science, released on Apr. 22, 2009, by the World Technology Assessment Center (WTEC).

"The startling news was how quickly our assumptions have to change," said Phillip Westmoreland, program director for combustion, fire and plasma systems at the National Science Foundation (NSF) and one of the sponsors of the report. "Because computer chip speeds aren't increasing, hundreds and thousands of chips are being ganged together, each one with a number of processors. New ways of programming are necessary".

Like other WTEC studies, this study was led by a team of leading scientists from a range of simulation science and engineering disciplines and involved site visits to research facilities around the world.

The nearly 400-page, multi-agency report highlights several areas in which the U.S. still maintains a competitive edge, including the development of novel algorithms, but also highlights endeavors that are increasingly driven by efforts in Europe or Asia, such as the creation and simulation of new materials from first principles......... Posted by: Kevin      Read more         Source

May 5, 2009, 5:16 AM CT

Clues for self-cleaning materials

Self-cleaning walls, counter tops, fabrics, even micro-robots that can walk on water -- all those things and more could be closer to reality because of research recently completed by researchers at the University of Nebraska-Lincoln and at Japan's RIKEN institute.

Humans have marveled for millennia at how water beads up and rolls off flowers, caterpillars and some insects, and how insects like water striders are able to walk effortlessly on water. It's a property called super hydrophobia and it's been examined seriously by researchers since at least the 1930s.

"A lot of people study this and engineers particularly like the water strider because it can walk on water," said Xiao Cheng Zeng, Ameritas university professor of chemistry at UNL. "Their legs are super hydrophobic and each leg can hold about 15 times their weight. 'Hydrophobic' means water really doesn't like their legs and that's what keeps them on top. A lot of researchers and engineers want to develop surfaces that mimic this from nature".

In a paper to be reported in the May 4-8 online edition of the Proceedings of the National Academy of Sciences, Zeng and his Japanese colleagues, Takahiro Koishi of the University of Fukui and RIKEN, Kenji Yasuoka of Keio University, and Shigenori Fujikawa and Toshikazu Ebisuzaki of RIKEN, give engineers and materials researchers important clues in how to develop the long-sought super hydrophobic materials......... Posted by: Kevin      Read more         Source

May 5, 2009, 5:14 AM CT

Particles, molecules prefer not to mix

In the world of small things, shape, order and orientation are surprisingly important, as per findings from a newly released study by chemists at Washington University in St. Louis.

Lev Gelb, WUSTL associate professor of chemistry, his graduate student Brian Barnes, and postdoctoral researcher Daniel Siderius, used computer simulations to study a very simple model of molecules on surfaces, which looks a lot like the computer game "Tetris." They have observed that the shapes in this model (and in the game) do many surprising things.

"First, different shapes don't mix very well with each other; each shape prefers to associate with others of the same kind," Gelb says. "When you put a lot of different shapes together, they separate from each other on microscopic scales, forming little clusters of nearly pure fluids. This is true even for the mirror-image shapes.

"Second, the structures of the pure (single-shape) fluids are quite complex and not what we might have predicted. There is a very strong tendency for some of the shapes, like rods and S- and Z- shapes, to align in the same direction. Finally, how `different looking' the shapes are isn't a good predictor for how well they mix; it turns out that the hard-to-predict characteristic structures of the fluids are more important than the shapes themselves, in this regard."........ Posted by: Kevin      Read more         Source

May 4, 2009, 5:16 AM CT

Nanotechnology holds promise

Yale scientists describe a breakthrough in safe and effective administration of potential antiviral drugs small interfering RNA (siRNA) molecules that silence genes the first step in development of a new kind of therapy for sexually transmitted diseases (STDs). The work is reported May 4 as an advance online publication of Nature Materials

"RNA interference is a promising approach for prevention and therapy of human disease," said main author Kim Woodrow, Yale postdoctoral fellow in Yale's School of Engineering & Applied Science. "We wanted to develop a new strategy of delivering siRNAs with a FDA-approved material".

As their name suggests, siRNAs interfere and knock out the function of genes in higher organism as well as in microbes that may cause STDs. The scientists designed siRNAs to target a gene expressed widely in the lining of the female mouse reproductive tract, in this proof-of-principle work.

Using densely-loaded nanoparticles made of a biodegradable polymer known as PLGA, the scientists created a stable "time release" vehicle for delivery of siRNAs to sensitive mucosal tissue like that of the female reproductive system.

They observed that the particles, loaded with the drug agent, moved effectively in two important ways, penetrating to reach cells below the surface of the mucosa and distributing throughout the vaginal, cervical, and uterine regions. Furthermore, the siRNAs stayed in the tissues for at least a week and knockdown of gene activity lasted up to 14 days......... Posted by: Kevin      Read more         Source

April 30, 2009, 5:50 PM CT

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April 27, 2009, 5:21 AM CT

How to catch the lightwave?

New Haven, Conn. As scientists push towards detection of single molecules, single electron spins and the smallest amounts of mass and movement, Yale scientists have demonstrated silicon-based nanocantilevers, smaller than the wavelength of light, that operate on photonic principles eliminating the need for electric transducers and expensive laser setups.

The work reported in an April 26 advance online publication of Nature Nanotechnology ushers in a new generation of tools for ultra-sensitive measurements at the atomic level.

In nanoelectromechanical systems (NEMS), cantilevers are the most fundamental mechanical sensors. These tiny structures fixed at one end and free at the other act like nano-scale diving boards that "bend" when molecules "jump" on them and register a change that can be measured and calibrated. This paper demonstrates how NEMS can be improved by using integrated photonics to sense the cantilever motion.

"The system we developed is the most sensitive available that works at room temperature. Previously this level of sensitivity could only be achieved at extreme low temperatures" said senior author Hong Tang, assistant professor of electrical and mechanical engineering in the Yale School of Engineering and Applied Sciences......... Posted by: Kevin      Read more         Source