November 8, 2007, 10:00 PM CT

Micro Microwave Does Pinpoint Cooking

Scientists at the National Institute of Standards and Technology (NIST) and George Mason University have demonstrated what is probably the world's smallest microwave oven, a tiny mechanism that can heat a pinhead-sized drop of liquid inside a container slightly shorter than an ant and half as wide as a single hair. The micro microwave is intended for lab-on-a-chip devices that perform rapid, complex chemical analyses on tiny samples.

In a paper in the November 2007 Journal of Micromechanics and Microengineering*, the research team led by NIST engineer Michael Gaitan describes for the first time how a tiny dielectric microwave heater can be successfully integrated with a microfluidic channel to control selectively and precisely the temperature of fluid volumes ranging from a few microliters (millionth of a liter) to sub-nanoliters (less than a billionth of a liter). Sample heating is an essential step in a wide range of analytic techniques that could be built into microfluidic devices, including the high-efficiency polymerase chain reaction (PCR) process that rapidly amplifies tiny samples of DNA for forensic work, and methods to break cells open to release their contents for study.

The team embedded a thin-film microwave transmission line between a glass substrate and a polymer block to create its micro microwave oven. A trapezoidal-shaped cut in the polymer block only 7 micrometers across at its narrowest-the diameter of a red blood cell-and nearly 4 millimeters long (approximately the length of an ant) serves as the chamber for the fluid to be heated......... Posted by: Kevin      Read more         Source

November 7, 2007, 6:59 PM CT

LHC completes the circle

At a brief ceremony deep under the French countryside today, CERN1 Director General Robert Aymar sealed the last interconnect in the world's largest cryogenic system, the Large Hadron Collider (LHC). This is the latest milestone in commissioning the LHC, the world's most powerful particle accelerator.

The LHC's cryogenic system has the task of cooling some 36 800 tonnes of material to a temperature of just 1.9 degrees above absolute zero (-271.3 degree C), colder than outer space. To do this, over 10 000 tonnes of liquid nitrogen and 130 tonnes of liquid helium will be deployed through a cryogenic system including over 40 000 leak-tight welds. Today's ceremony marks the end of a two year programme of work to connect all the main dipole and quadrupole magnets in the LHC. This complex task included both electrical and fluid connections.

"This is a huge accomplishment," said Lyn Evans, LHC project leader. "Now that it is done, we can concentrate on getting the machine cold and ready for physics."

The LHC is a circular machine, 27 kilometres around and divided into eight sectors, each of which can be cooled down to its operating temperature of 1.9 degrees above absolute zero and powered-up individually. One sector was cooled down, powered and warmed up in the first half of 2007. This was an important learning process, allowing subsequent sectors to be tested more quickly......... Posted by: Sarah      Read more         Source

November 7, 2007, 4:49 AM CT

Enhancing Mother Nature's carbon handling mechanism

Taking a page from Nature herself, a team of scientists developed a method to enhance removal of carbon dioxide from the atmosphere and place it in the Earth's oceans for storage.

Unlike other proposed ocean sequestration processes, the new technology does not make the oceans more acid and may be beneficial to coral reefs. The process is a manipulation of the natural weathering of volcanic silicate rocks.

Reporting in today's (Nov. 7) issue of Environmental Science and Technology, the Harvard and Penn State team explained their method.

"The technology involves selectively removing acid from the ocean in a way that might enable us to turn back the clock on global warming," says Kurt Zenz House, graduate student in Earth and planetary sciences, Harvard University. "Essentially, our technology dramatically accelerates a cleaning process that Nature herself uses for greenhouse gas accumulation".

In natural silicate weathering, carbon dioxide from the atmosphere dissolves in fresh water and forms weak carbonic acid. As the water percolates through the soil and rocks, the carbonic acid converts to a solution of alkaline carbonate salts. This water eventually flows into the ocean and increases its alkalinity. An alkaline ocean can hold dissolved carbon, while an acidic one will release the carbon back into the atmosphere. The more weathering, the more carbon is transferred to the ocean where some of it eventually becomes part of the sea bottom sediments......... Posted by: Kevin      Read more         Source

November 6, 2007, 10:34 PM CT

Stream of sand grains, exotic plasma at birth of universe

Streams of granular particles bouncing off a target in a simple tabletop experiment produce liquid-like behavior also witnessed in a massive research apparatus that simulates the birth of the universe. A team led by the University of Chicago's Sidney Nagel and Heinrich Jaeger report this surprising finding in the Oct. 27-Nov. 2 issue of Physical Review Letters.

"Nature plays the tricks that it knows how to play over and over again," said Nagel, the Stein Freiler Distinguished Service Professor in Physics at Chicago. Nagel and Jaeger co-authored the paper, along with Xiang Cheng, a graduate student in physics at Chicago; German Varas, a graduate student in physics at the University of Chile; and Daniel Citron, a Chicago undergraduate in physics.

Researchers have attained a good understanding of equilibrium phenomena, which are governed primarily by temperature or pressure. But what about phenomena that have been pushed far beyond their equilibrium states, like a jet of sand" What about quark-gluon plasma, the mixture of subatomic particles that existed for perhaps a few millionths of a second after the big bang".

"We really don't know what the right concepts are to describe this," Nagel said. "We love the physics of granular material because it allows us entre into this question in relatively simple experiments"......... Posted by: Kevin      Read more         Source

November 4, 2007, 8:07 PM CT

Heavier hydrogen on the atomic scale

Researchers may be one step closer to understanding the atomic forces that cause friction, thanks to a recently published study by scientists from the University of Pennsylvania, the University of Houston and the U.S. Department of Energy's Argonne National Laboratory.

The research, led by Robert Carpick of the University of Pennsylvania, found a significant difference in friction exhibited by diamond surfaces that had been coated with different isotopes of hydrogen and then rubbed against a small carbon-coated tip.

Researchers lack a comprehensive model of friction on the nanoscale and only generally grasp its atomic-level causes, which range from local chemical reactions to electronic interactions to phononic, or vibrational, resonances.

To investigate the latter, Argonne scientist Anirudha Sumant and colleagues used single-crystal diamond surfaces coated with layers of either atomic hydrogen or deuterium, a hydrogen atom with an extra neutron. The deuterium-terminated diamonds had lower friction forces because of their lower vibrational frequencies, an observation that Sumant attributed to that isotope's larger mass. They have also observed same trend on a silicon substrate, which is structurally similar to that of diamond.

Prior attempts to make hydrogen-terminated diamond surfaces relied on the use of plasmas, which tended to etch the material......... Posted by: Kevin      Read more         Source

November 1, 2007, 8:04 PM CT

Light-powered micro-machines

A new theory developed at MIT could lead to "smart" optical microchips that adapt to different wavelengths of light, potentially advancing telecommunications, spectroscopy and remote sensing.

Drawn by the promise of superior system performance, scientists have been exploring the concept of microchips that manipulate light instead of electricity. In their new theory, the MIT team has shown how such chips could feature tiny machines with moving parts powered and controlled by the very light they manipulate, giving rise to fundamentally new functionality.

"There are thousands of complex functions we could make happen by tinkering with this idea," said Peter Rakich, an MIT postdoctoral associate who invented the theoretical concept along with postdoc Milos Popovic. The work was described in the cover story of the recent issue of Nature Photonics.

For example, such chips could one day be used to remotely adjust the amount of bandwidth available in an optical network, or to automatically process signals flowing through fiber-optic networks, without using any electrical power, Rakich said.

Coauthors on the paper were Marin Soljacic, assistant professor of physics; and Erich Ippen, the Elihu Thomson Professor of Electrical Engineering and professor of physics......... Posted by: Kevin      Read more         Source

October 31, 2007, 7:30 PM CT

First Fully Functional Nanotube Radio

Make way for the real nanopod and make room in the Guinness World Records. A team of scientists with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have created the first fully functional radio from a single carbon nanotube, which makes it by several orders of magnitude the smallest radio ever made.

"A single carbon nanotube molecule serves simultaneously as all essential components of a radio - antenna, tunable band-pass filter, amplifier, and demodulator," said physicist Alex Zettl, who led the invention of the nanotube radio. "Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation (FM and AM), we were able to demonstrate successful music and voice reception."

Given that the nanotube radio essentially assembles itself and can be easily tuned to a desired frequency band after fabrication, Zettl believes that nanoradios will be relatively easy to mass-produce. Potential applications, in addition to incredibly tiny radio receivers, include a new generation of wireless communication devices and monitors. Nanotube radio technology could prove particularly valuable for biological and medical applications.

"The entire radio would easily fit inside a living cell, and this small size allows it to safely interact with biological systems," Zettl said. "One can envision interfaces with brain or muscle functions, or radio-controlled devices moving through the bloodstream"......... Posted by: Kevin      Read more         Source

October 31, 2007, 7:21 PM CT

Let there be light

Engineers at Florida State Universitys National High Magnetic Field Laboratory have successfully tested a groundbreaking new magnet design that could literally shed new light on nanoscience and semiconductor research.

When the magnet -- called the Split Florida Helix -- is operational in 2010, scientists will have the ability to direct and scatter laser light at a sample not only down the bore, or center, of the magnet, but also from four ports on the sides of the magnet, while still reaching fields above 25 tesla. By comparison, the highest-field split magnet in the world attains 18 tesla. Tesla is a measurement of the strength of a magnetic field; 1 tesla is equal to 20,000 times the Earths magnetic field.

Magnetism is a critical component of a surprising number of modern technologies, including MRIs and disk drives, and high-field magnets stand beside lasers and microscopes as essential research tools for probing the mysteries of nature. With this new magnet, researchers will be able to expand the scope of their experimental approach, learning more about the intrinsic properties of materials by shining light on crystals from angles not previously available in such high magnetic fields. In materials research, researchers look at which kinds of light are absorbed or reflected at different crystal angles, giving them insight into the fundamental electronic structure of matter......... Posted by: Kevin      Read more         Source

October 30, 2007, 10:19 PM CT

Most Complex Silicon Phased Array Chip in the World

UC San Diego electrical engineers have developed the world's most complex "phased array" -- or radio frequency integrated circuit. This DARPA-funded advance is expected to find its way into U.S. defense satellite communication and radar systems. In addition, the innovations in this chip design will likely spill over into commercial applications, such as automotive satellite systems for direct broadcast TV, and new methods for high speed wireless data transfer.

"This is the first 16 element phased array chip that can send at 30-50 GHz. The uniformity and low coupling between the elements, the low current consumption and the small size - it is just 3.2 by 2.6 square millimeters - are all unprecedented. As a whole system, there are many many firsts," said Gabriel Rebeiz, the electrical engineering professor from the UCSD Jacobs School of Engineering leading the project. The work was done by two graduate students, Kwang-Jin Koh and Jason May, both at the Electrical and Computer Engineering Department (ECE) at UCSD. Rebeiz presented the new chip at DARPA TEAM Meeting, August 28-29, 2007 in Chicago, Illinois. Additional details of the chip will be submitted to an academic journal later this year.

This chip - the UCSD DARPA Smart Q-Band 4x4 Array Transmitter - is strictly a transmitter. "We are working on a chip that can do a transmit and receive function," said Rebeiz......... Posted by: Kevin      Read more         Source

October 30, 2007, 9:59 PM CT

Wireless Sensors To Monitor Bearings In Jet Engines

working with the U.S. Air Force, have developed tiny wireless sensors resilient enough to survive the harsh conditions inside jet engines to detect when critical bearings are close to failing and prevent breakdowns.

The devices are an example of an emerging technology known as "micro electromechanical systems," or MEMS, which are machines that combine electronic and mechanical components on a microscopic scale.

"The MEMS technology is critical because it needs to be small enough that it doesn't interfere with the performance of the bearing itself," said Farshid Sadeghi, a professor of mechanical engineering. "And the other issue is that it needs to be able to withstand extreme heat".

The engine bearings must function amid temperatures of about 300 degrees Celsius, or 572 degrees Fahrenheit.

The scientists have shown that the new sensors can detect impending temperature-induced bearing failure significantly earlier than conventional sensors.

"This kind of advance warning is critical so that you can shut down the engine before it fails," said Dimitrios Peroulis, an assistant professor of electrical and computer engineering.

Findings will be detailed in a research paper to be presented on Tuesday (Oct. 30) during the IEEE Sensors 2007 conference in Atlanta, sponsored by the Institute of Electrical and Electronics Engineers. The paper was written by electrical and computer engineering graduate student Andrew Kovacs, Peroulis and Sadeghi......... Posted by: Kevin      Read more         Source