June 7, 2007, 7:27 PM CT

Turning the tables in chemistry

Waltham, MAWhat do glowing veggies have to do with a career in science" It just so happens that electrified pickles swimming in metal ions are one example of the type of undergraduate chemistry class demonstration that helps make a future in science a bright possibility, rather than a total turn-off, for a number of students.

In a commentary in this months Nature Chemical Biology, Brandeis University and Howard Hughes Medical Institute (HHMI) Professor Irving Epstein outlines a gathering storm clouding the future of U.S. science and prescribes a series of strategies to help avert a looming national crisis. Epstein says the continued success of U.S. science is seriously threatened by the fact that increasing numbers of undergraduates, especially the disadvantaged, are writing off a career in science.

Why? A number of students find introductory science, and chemistry in particular, both difficult and dull the way it is conventionally taught at the college level, discouraging a number of potential researchers before they ever have the chance to get hooked on science.

Anyone who teaches an introductory science course at one of this countrys elite universities is familiar with the sea of white faces he or she encounters, and the tendency of that ocean to whiten even more as the semester progresses and as one moves up the ladder of courses, writes Epstein, who last year won $1 million from HHMI to revamp introductory chemistry at Brandeis with an eye to luringand retainingmore students in science, especially disadvantaged ones......... Posted by: Sarah      Read more         Source

May 25, 2007, 3:24 PM CT

NIST Atom Interferometry Displays New Quantum Tricks

Physicists at the National Institute of Standards and Technology (NIST) have demonstrated a novel way of making atoms interfere with each other, recreating a famous experiment originally done with light while also making the atoms do things that light just won't do. Their experiments showcase some of the extraordinary behavior taken for granted in the quantum world-atoms acting like waves and appearing in two places at once, for starters-and demonstrate a new technique that could be useful in quantum computing with neutral atoms and further studies of atomic hijinks.

The NIST experiments, described in Physical Review Letters,* recreate the historic "double-slit" experiment in which light is directed through two separate openings and the two resulting beams interfere with each other, creating a striped pattern. That experiment is a classic demonstration of light behaving like a wave, and the general technique, called interferometry, is used as a measurement tool in a number of fields. The NIST team used atoms, which, like light, can behave like particles or waves, and made the wave patterns interfere, or, in one curious situation, not.

Atom interferometers have been made before, but the NIST technique introduces some new twists. The scientists trap about 20,000 ultracold rubidium atoms with optical lattices, a lacework of light formed by three pairs of infrared laser beams that sets up an array of energy "wells," shaped like an egg carton, that trap the atoms. The lasers are arranged to create two horizontal lattices overlapping like two mesh screens, one twice as fine as the other in one dimension. If one atom is placed in each site of the wider lattice, and those lasers are turned off while the finer lattice is activated, then each site is split into two wells, about 400 nanometers apart. Under the rules of the quantum world, the atom doesn't choose between the two sites but rather assumes a "superposition," located in both places simultaneously. Images reveal a characteristic pattern as the two parts of the single superpositioned atom interfere with each other. (The effect is strong enough to image because this is happening to thousands of atoms simultaneously-see image.)......... Posted by: Sarah      Read more         Source

May 10, 2007, 10:31 PM CT

Electrons Caught in the Act of Tunnelling

In the same way as gravity brings a body to a halt on the floor of a valley, the nuclear force (which binds protons and neutrons to form the atomic nucleus) and the electrical force (which combines negatively charged electrons with the positively charged atomic nucleus to make an atom) hold these particles within a tiny space. This binding effect can also be depicted as a type of valley, which is also called a potential by physicists. In the world of quantum particles, it is, to a certain extent, a normal event to tunnel through the wall surrounding the potential well. An international team of scientists working with Ferenc Krausz has now caught the electrons in the act of tunnelling through the binding potential of the atom nucleus under the influence of laser light. The physicists used the new tools provided by attosecond metrology. "For the first time, our findings confirmed in real time observation the theoretical predictions of quantum mechanics," says Ferenc Krausz, Director at the Max Planck Institute for Quantum Optics and head of the team of scientists.

The tunnelling effect can be explained by the wave behaviour of each particle. Macroscopic objects are extremely unlikely to tunnel, which is why the phenomenon has never been observed in them. In contrast, there is a significant probability that particles from the microcosmos will tunnel through areas where, as per the rules of traditional physics, they are not even supposed to be. The tunnelling effect is considered to be responsible for processes as varied as atomic nuclei decay and the switching process in electronic components. However, since it only lasts for an extremely short time, it has still not been observed in real time......... Posted by: Sarah      Read more         Source

May 9, 2007, 10:30 PM CT

New Materials To Make Hydrogen More Stable

Carnegie Mellon University's David S. Sholl is working to identify new materials that would help make hydrogen more stable and cost-efficient than fossil fuels. Increased concern about global warming and a need to conserve natural fuel sources prompted Carnegie Mellon scientists to find new, lightweight, low-cost hydrogen-storage materials.

"We are currently studying the use of metal hydrides, such as alanates and borohydrides, to find materials that could ultimately improve the efficiency of hydrogen cars and curb pollution," said Sholl, a professor of chemical engineering.

Essentially, what Sholl and his research team are trying to do is create a new material that will store larger amounts of hydrogen than can be held in a compressed gas tank, but will still be able to easily release the hydrogen to feed the fuel cell for cars of the future. Hydrogen-powered cars run on fuel cells that combine hydrogen and oxygen from the air to produce electricity. The only waste emitted is water.

By contrast, engines that burn gasoline emit pollutants, such as carbon dioxide, that cause global warming. U.S. vehicles consume 383 million gallons of gasoline a day or about 140 billion gallons annually. That's about two-thirds of the total national oil consumption, half of which is imported from overseas......... Posted by: Sarah      Read more         Source

April 24, 2007, 10:35 PM CT

Avalanche Behavior Of Superfluid Helium

By utilizing ideas developed in disparate fields, from earthquake dynamics to random-field magnets, scientists at the University of Illinois have constructed a model that describes the avalanche-like, phase-slip cascades in the superflow of helium.

Just as superconductors have no electrical resistance, superfluids have no viscosity, and can flow freely. Like superconductors, which can be used to measure extremely tiny magnetic fields, superfluids could create a new class of ultra-sensitive rotation sensors for use in precision guidance systems and other applications.

But, before new sensors can be built, researchers and engineers must first acquire a better understanding of the odd quirks of superfluids arising in these devices.

In the April 23 issue of Physical Review Letters, U. of I. physicist Paul Goldbart, graduate student David Pekker and postdoctoral research associate Roman Barankov describe a model they developed to explain some of those quirks, which were found in recent experiments conducted by scientists at the University of California at Berkeley.

In the Berkeley experiments, physicist Richard Packard and his students Yuki Sato and Emile Hoskinson explored the behavior of superfluid helium when forced to flow from one reservoir to another through an array of several thousand nano-apertures. Their intent was to amplify the feeble whistling sound of phase-slips linked to superfluid helium passing through a single nano-aperture by collecting the sound produced by all of the apertures acting in concert......... Posted by: Sarah      Read more         Source

April 24, 2007, 10:20 PM CT

New Family of Pseudo-Metallic Chemicals

The periodic table of elements, all 111 of them, just got a little competition. A new discovery by a University of Missouri-Columbia research team, published in Angewandte Chemie, the journal of the German Society of Chemists, allows researchers to manipulate a molecule discovered 50 years ago in such as way as to give the molecule metal-like properties, creating a new, "pseudo" element. The pseudo-metal properties can be adjusted for a wide range of uses and might change the way researchers think about attacking disease or even building electronics.

Five decades ago, Fred Hawthorne, professor of radiology and director of the International Institute for Nano and Molecular Medicine at MU, discovered an extremely stable molecule consisting of 12 boron atoms and 12 hydrogen atoms. Known as "boron cages," these molecules were difficult to change or manipulate, and sat dormant in Hawthorne's laboratory for a number of years.

Recently, Hawthorne's scientific team found a way to modify these cages, resulting in a large, new family of nano-sized compounds. In their study, which was published this month, Hawthorne, and Mark Lee, assistant professor at the institute and first author of the study, observed that attaching different compounds to the cages gave them the properties of a number of different metals......... Posted by: Sarah      Read more         Source

April 17, 2007, 10:52 PM CT

Rethinking Zinc

Try as they might, ancient alchemists could never turn lead into gold. Neither can the members of the Novel Materials group at the U.S. Department of Energy's Ames Laboratory. But these physicists do have a way with materials, and they can get them to do some pretty amazing things.

Drs. Paul Canfield and Sergey Bud'ko and their Iowa State University Department of Physics and Astronomy graduate student, Shuang Jia, have discovered a new family of zinc compounds that can be tuned, or manipulated, to take on some of the physical properties and behavior of other materials, ranging from plain old copper to more exotic elements like palladium, to even more complex electronic and magnetic compounds that are on, as Canfield said, "the hairy edge" of becoming magnetic (or even superconducting).

Their versatility makes the new zinc compounds ideal for basic research efforts to observe and learn more about the origins of phenomena such as magnetism. Basic research is the building block. Once researchers understand how these materials work, products and/or processes can follow.

In addition, zinc is very cheap. In 1982, the U.S.Mint switched the composition of the penny to 97.5 percent zinc and only 2.5 percent copper. In a similar manner, this class of compounds is over 85 percent zinc. If technological applications can be found, these compounds will literally only cost pennies to make......... Posted by: Sarah      Read more         Source

April 16, 2007, 10:13 PM CT

Was Einstein right?

For the past three years a satellite has circled the Earth, collecting data to determine whether two predictions of Albert Einstein's general theory of relativity are correct. Today, at the American Physical Society (APS) meeting in Jacksonville, Fla., Professor Francis Everitt, a Stanford University physicist and principal investigator of the Gravity Probe B (GP-B) Relativity Mission, a collaboration of Stanford, NASA and Lockheed Martin, will provide the first public peek at data that will reveal whether Einstein's theory has been confirmed by the most sophisticated orbiting laboratory ever created.

"Gravity Probe B has been a great scientific adventure for all of us, and we are grateful to NASA for its long history of support," Everitt said. "My colleagues and I will be presenting the first results today and tomorrow. It's fascinating to be able to watch the Einstein warping of space-time directly in the tilting of these GP-B gyroscopes-more than a million times better than the best inertial navigation gyroscopes."

The GP-B satellite was launched in April 2004. It collected more than a year's worth of data that the Stanford GP-B science team has been poring over for the past 18 months. The satellite was designed as a pristine, space-borne laboratory, whose sole task was to use four ultra-precise gyroscopes to measure directly two effects predicted by general relativity. One is the geodetic effect-the amount by which the mass of the Earth warps the local space-time in which it resides. The other effect, called frame-dragging, is the amount by which the rotating Earth drags local space-time around with it. As per Einstein's theory, over the course of a year, the geodetic warping of Earth's local space-time causes the spin axes of each gyroscope to shift from its initial alignment by a minuscule angle of 6.606 arc-seconds (0.0018 degrees) in the plane of the spacecraft's orbit. Likewise, the twisting of Earth's local space-time causes the spin axis to shift by an even smaller angle of 0.039 arc-seconds (0.000011 degrees)-about the width of a human hair viewed from a quarter mile away-in the plane of the Earth's equator......... Posted by: Sarah      Read more         Source

April 12, 2007, 6:17 PM CT

Titanium Dioxide: It Slices, It Dices

Chemists from the National Institute of Standards and Technology (NIST) and Arizona State University have proposed an elegantly simple technique for cleaving proteins into convenient pieces for analysis. The prototype sample preparation method, detailed recently in Analytical Chemistry,* uses ultraviolet light and titanium dioxide and could be ideal for new microfluidic "lab-on-a-chip" devices designed to rapidly analyze minute amount of biological samples.

Because most proteins are very large, complex molecules made up of hundreds or thousands of amino acids, they commonly must be cut up into more manageable pieces for analysis. Today, this most usually is done by using special enzymes called "proteases" that sever the chains at well-known locations. The protease trypsin, for example, cuts proteins at the locations of the amino acids lysine and arginine. Analyzing the residual fragments can identify the original protein. But enzymes are notoriously fussy, demanding fairly tight control of temperature and acidity, and the enzymatic cutting process can be time-consuming, from a matter of hours to days.

For a "radically" different approach, the NIST group turned to a semiconductor material, titanium dioxide. Titanium dioxide is a photocatalyst-when exposed to ultraviolet light its surface becomes highly oxidizing, converting nearby water molecules into hydroxyl radicals, a short-lived, highly reactive chemical species.** In the NIST experiments, titanium dioxide coatings were applied to a variety of typical microanalysis devices, including microfluidic channels and silica beads in a microflow reactor. Shining a strong UV light on the area, in the presence of a protein solution, creates a small "cleavage zone" of hydroxyl radicals that rapidly cut nearby proteins at the locations of the amino acid proline......... Posted by: Sarah      Read more         Source

April 1, 2007, 9:45 PM CT

The world's largest particle accelerator

The last quadripolar magnet was brought down into the tunnel of the worlds largest particle accelerator; the CERNs1 LHC, or Large Hadron Collidor. This magnet is part of a series of 392 units which will ensure that the beams are kept on track all along their trajectory through the tunnel. Its installation marks the completion of a long and fruitful collaboration between the CERN, the CNRS/IN2P32 and the CEA/DSM3 in the field of superconductivity and advanced cryogenics. This collaboration has lasted over ten years and was part of the special contribution made by France, as the host country, to the construction of the LHC.

Built to answer the most fundamental questions in physics, the LHC accelerator is assembled at the CERN in a tunnel which has a circumference of 27 km and is buried 100 metres beneath the Franco-Swiss border. It is composed of 1700 large magnets of which 392 are quadripole magnets designed to guide and focus the beams. It also includes a significant quantity of corrective magnets. The final installation of the LHC will be completed in mid-2007, and start-up is planned for November 2007.

In order to meet the considerable technological challenges presented by the LHC, the CNRS, CEA and CERN collaborated closely in the construction of the accelerator. The protocol of collaboration amongst these three organizations was signed on February 14, 1996 in the presence of the Minister responsible for research......... Posted by: Sarah      Read more         Source