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October 9, 2006, 9:04 PM CT

Hot Nanocrystals

Hot Nanocrystals
Researchers at the Department of Energy's Lawrence Berkeley National Laboratory have discovered that nanocrystals of germanium embedded in silica glass don't melt until the temperature rises almost 200 degrees Kelvin above the melting temperature of germanium in bulk. What's even more surprising, these melted nanocrystals have to be cooled more than 200 K below the bulk melting point before they resolidify. Such a large and nearly symmetrical "hysteresis" - the divergence of melting and freezing temperatures above and below the bulk melting point - has never before been observed for embedded nanoparticles.

Phase transitions between solid and liquid or liquid and vapor are familiar phenomena in the everyday world, for example between solid water ice, liquid water, and water vapor, or steam. Eugene Haller of Berkeley Lab's Materials Sciences Division (MSD), who is also a professor of materials science at the University of California at Berkeley, uses an epicurean example: "When a solid piece of chocolate melts in the mouth, it releases a burst of flavors."

Haller explains that beyond broad scientific interest, the properties of germanium nanoparticles embedded in amorphous silicon dioxide matrices have promising applications. "Germanium nanocrystals in silica have the ability to accept charge and hold it stably for long periods, a property which can be used in improved computer memory systems. Moreover, germanium dioxide (germania) mixed with silicon dioxide (silica) offers particular advantages for forming optical fibers for long-distance communication."........

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October 9, 2006, 8:54 PM CT

Weaknesses In High-tech Immigration

Weaknesses In High-tech Immigration
Legislation pending before Congress "would admit foreign computing and engineering (C&E) workers in numbers much greater than historical trends or casual assumptions about future employment levels," according to a recent study from Georgetown University, commissioned by IEEE-USA.

The August report from Georgetown's Institute for the Study of International Migration concluded that the estimated number of new high-tech visas available under the "Comprehensive Immigration Reform Act of 2006" (S.2611) over the next 10 years could be 1.88 million. The Bureau of Labor Statistics estimates the number of new C&E workers needed by our economy over the decade is 1.25 million.

Thus, Congress was considering authorizing enough high-skill visas to fill every C&E job created in the United States over the next decade and still have 630,000 visas left over.

"The report calls into question Congress' approach to high-skill immigration reform," IEEE-USA President Ralph W. Wyndrum Jr. said. "Its analysis provides needed context to the immigration numbers being discussed on Capitol Hill".........

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October 9, 2006, 8:42 PM CT

Keeping Oil, Gas Control Systems Safe

Keeping Oil, Gas Control Systems Safe
For the past 12 months, Sandia National Laboratories has served as the lead national lab in Project LOGIIC (Linking the Oil and Gas Industry to Improve Cyber Security). The project was created to keep U.S. oil and gas control systems safe and secure, and to help minimize the chance that a cyber attack could severely damage or cripple AmericaTMs oil and gas infrastructure.

Such an attack by viruses, worms or other forms of cyber-terrorism on oil and gas industry process control networks and related systems could destabilize energy industry supply capabilities and negatively impact the national economy.

LOGIIC, funded by the Department of Homeland Security's Science and Technology Directorate, brought together 14 organizations to identify ways to reduce cyber vulnerabilities in process control and SCADA (Supervisory Control And Data Acquisition) systems. The goal of the project was to identify new types of security sensors for process control networks.

Sandia worked with project partners to create a simulation test bed and apply this environment to counter potential threats to the oil and gas industry using hypothetical attack scenarios. Sandia researchers created two real-time models of control systems used for refinery and pipeline operations.........

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October 5, 2006, 10:10 PM CT

Clinical Applications For New DESI Technology

Clinical Applications For New DESI Technology
Purdue University scientists have created the first two-dimensional images of biological samples using a new mass spectrometry technique that furthers the technology's potential applications for the detection of diseases such as cancer.

The technology, desorption electrospray ionization, or DESI, measures characteristic chemical markers that distinguish diseased from non-diseased regions of tissue samples within a few seconds and has eliminated the need for samples to be treated with chemicals and specially contained.

This tool has a wide range of applications and could be used in the future to address a number of medical issues, said Graham Cooks, Purdue's Henry B. Hass Distinguished Professor of Analytical Chemistry in whose lab DESI was developed.

"This technology could be used to aid surgeons in precisely and completely removing malignant tissue," he said. "With these images, we can see the exact location of tumor masses and can detect malignant sites that are indistinguishable to the naked eye".

Current surgical methods rely on the trained eye of a pathologist who views stained tissue slices under a microscope to assess what tissue must be removed.

This study was the first to take the graphical data presented by DESI mass spectrometry and turn it into a two-dimensional image of the tissue, said Demian Ifa, a member of Cooks' research team.........

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October 5, 2006, 10:04 PM CT

Experiment Yields Bubbly Surprise

Experiment Yields Bubbly Surprise Asymmetrical pinch-off of a burst of air from a slot-shaped nozzle.
Credit: Nathan Keim, University of Chicago
University of Chicago physicists have discovered a new class of behavior in air bubbles rising from an underwater nozzle. In this surprising behavior, the bubbles tear apart in sharp jerks instead of pinching off at a point, the research team will report in the Oct. 6 issue of the journal Physical Review Letters.

The research is helping researchers understand the mathematical explosions they encounter in the equations that govern the physics of fluids. "These are the equations of our lives," said Wendy Zhang, Assistant Professor in Physics at the University of Chicago. They govern everything from the bubbles of carbonated beverages to the venting of gas from deep oceanic fissures. They even apply to such large-scale processes such as exploding stars.

"One of the things that's nice about this field of research is that it's around you all the time," said Sidney Nagel, the Stein-Freiler Distinguished Service Professor in Physics at the University of Chicago. "It's on your tabletop and you've seen it who knows how a number of times. But by studying this so incredibly carefully, you get insights about things that happen on the celestial scale".

Chicago graduate student Nathan Keim and his co-authors-Zhang, Nagel, and Peder Moller, now a Ph.D. student at Ecole Normale Suprieure-documented their discovery using high-speed digital photography. Keim's experiment built on prior work that Zhang, Nagel and others published in Science in 2003. Until then, researchers believed that all fluids broke apart in much the same way. They believed that the cross-section of the pinching neck of any drop or bubble would become circular until it broke, regardless of its initial conditions.........

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October 4, 2006, 8:15 PM CT

Carbon Nanotubes To Detect Defects In Composites

Carbon Nanotubes To Detect Defects In Composites
Two University of Delaware scientists have discovered a means to detect and identify damage within advanced composite materials by using a network of tiny carbon nanotubes, which act in much the same manner as human nerves.

The discovery has important implications both in the laboratory, where the researchers hope to better predict the life span of various composite materials, and in everyday applications, where it could become an important tool in monitoring the health of composite materials used in the construction of a variety of essential products, including commercial airliners.

The research is the work of Tsu-Wei Chou, Pierre S. du Pont Chair of Engineering, and Erik Thostenson, assistant professor of mechanical engineering, and is featured in an article in the Oct. 2 issue of the influential journal Advanced Materials.

Chou said the research team has been working in the field of fiber composites in conjunction with UD's Center for Composite Materials and of late has taken an interest in the reinforcement of composites with minute nanomaterials--a nanometer is a bare one billionth of one meter--and especially with carbon nanotubes.

"Carbon nanotubes are very small but have superb qualities," Chou said. "They are very light, with a density about one-half that of aluminum, which itself is considered exceptionally light compared to other metals, and yet are 30 times as strong as high-strength steel and as stiff as diamonds".........

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October 3, 2006, 10:11 PM CT

Nanoparticles To Aid Brain Imaging

Nanoparticles To Aid Brain Imaging Sensing calcium as it flows into neurons following firing can potentially track information flow throughout the brain's circuitry.
If you want to see precisely what the 10 billion neurons in a person's brain are doing, a good way to start is to track calcium as it flows into neurons when they fire.

To that end, Alan Jasanoff at the McGovern Institute for Brain Research at MIT has developed a new nano-sized calcium-sensing contrast agent that is detectable by magnetic resonance imaging (MRI) scanners, machines that can be used for detailed noninvasive brain imaging.

The work is published in the early online edition of the Proceedings of the National Academy of Sciences the week of Sept. 25-29.

In an application known as functional MRI (fMRI), MRI machines are already increasingly used to observe brain functions as people--or animals--undertake various activities like reading or learning. But Jasanoff notes that current fMRI technology has limitations.

"Using conventional fMRI to study the brain is like trying to understand how a computer works by feeling which parts of it are hot because of energy dissipation in different components," said Jasanoff, who also holds appointments as an assistant professor in MIT's Department of Nuclear Science and Engineering, Department of Brain and Cognitive Sciences, and Biological Engineering Division.

The analogy is apt, because fMRI indirectly measures neural activity by detecting changes in blood flow to brain regions with increased energy requirements. But these hemodynamic changes occur several seconds after the neurons actually fire, too slow to study precise neural activity. Further, the spacing of tiny blood vessels limits the spatial resolution of the technique to volumes containing at least 1,000 neurons, too coarse for discrimination of highly specialized functional areas within a brain region.........

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October 3, 2006, 10:07 PM CT

Robot Wheelchair Gives Patients More Independence

Robot Wheelchair Gives Patients More Independence
Engineers at the National Institute of Standards and Technology (NIST) are developing a robotic system that may offer wheelchair-dependent people independent, powered mobility and the ability, depending on patient status, to move to and from beds, chairs and toilets without assistance.*.

The lifting ability of the system, which is called the "HLPR Chair" (for Home Lift, Position and Rehabilitation), also should significantly reduce caregiver and patient injuries.

The HLPR chair draws on mobile robotic technology developed at NIST for defense and manufacturing applications. It is built on an off-the-shelf forklift with a U-frame base on wheel-like casters and a rectangular vertical frame. The frame is small enough to pass through the typical residential bathroom. The user drives the chair using a joystick and other simple controls.

The HLPR chair's drive, steering motors, batteries and control electronics are positioned to keep its center of gravity-even when carrying a patient-within the wheelbase. This allows a person, weighing up to 300 pounds, to rotate out, from the inner chair frame, over a toilet, chair or bed while supported by torso lifts. The torso lifts lower the patient safely into the new position. The chair frame can even remain in position to continue supporting the patient from potential side, back or front fall.........

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October 3, 2006, 10:02 PM CT

Nanotechnology to Stop Weaponized Anthrax

Nanotechnology to Stop Weaponized Anthrax
Picture a spider web coated with sugar. But instead of luring in unsuspecting creatures, this spider web pulls in deadly anthrax spores, rendering them harmless.

Clemson University chemist Ya-Ping Sun and his research team have developed such a countermeasure strategy to weaponized anthrax, a biological agent used by a terrorist or terrorists that killed five Americans in 2001. The Clemson team's findings are published online in the "Journal of the American Chemical Society".

"For anthrax to be effective, it has to be made into a fine powder that can easily enter the lungs when inhaled. That is what makes it lethal," said Sun. "What we have done is come up with an agent that clings to the anthrax spores to make their inhalation into the lungs difficult".

Anthrax spores are covered with carbohydrates, or simple sugars, that are used to communicate with or attract other biological species. The Clemson team used carbon nanotubes as a platform or scaffolding for displaying sugar molecules that would attract the anthrax spores. Carbon nanotubes are hollow tubes made of carbon atoms. Typically one-hundred thousandth the thickness of a single human hair, nanotubes are formed from intensely heated carbon. When sugar coated, the carbon nanotubes bind with the anthrax spores, creating clusters that are too large to be inhaled -- stopping their infection and destruction.........

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October 2, 2006, 9:29 PM CT

A Magnetic-Semiconductor Sandwich

A Magnetic-Semiconductor Sandwich
Scientists at Ohio University have created an improved magnetic semiconductor that solves a problem spintronics researchers have been investigating for years.

Unlike classic or vintage electronics that operate on electronic charges, spin-based electronics focuses on the spin of electrons to carry and store information. Scientists predict spintronics will revolutionize the electronics industry by making devices faster, improving storage capacity and reducing the amount of power needed to run them.

Spintronics technology has not been widely applied yet, however, because researchers have had difficulty controlling, manipulating and measuring the electrons.

In a paper published online today in Physical Review Letters, a team of Ohio University and Ohio State University researchers led by postdoctoral fellow Erdong Lu have created an effective interface between a semiconductor and ferromagnetic metal. The two-layer "sandwich" of gallium nitride (GaN) and manganese gallium (MnGa) nearly eliminates any intermixing of the two layers and allows the spin to be "tuned".

"We found a way to grow the metal on the semiconductor. The crystalline match between the two materials was nearly perfect. The advantage of this finding is in the growth process. By adjusting the conditions of the growth, we can tune the spin," said Arthur Smith, associate professor of physics and astronomy and director of Ohio University's Nanoscale & Quantum Phenomena Institute.........

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