March 29, 2006, 10:39 PM CT

Ocean 'dead zones' posing extinction threat

Oxygen depletion in the world's oceans, primarily caused by agricultural run-off and pollution, could spark the development of far more male fish than female, thereby threatening some species with extinction, as per a research studypublished recently on the Web site of the American Chemical Society journal, Environmental Science & Technology. The study is scheduled to appear in the May 1 print issue of the journal.

The finding, by Rudolf Wu, Ph.D., and his colleagues at the City University of Hong Kong, raises new concerns about vast areas of the world's oceans, known as "dead zones," that lack sufficient oxygen to sustain most sea life. Fish and other creatures trapped in these zones often die. Those that escape may be more vulnerable to predators and other stresses. This new study, Wu says, suggests these zones potentially pose a third threat to these species - an inability of their offspring to find mates and reproduce.

The scientists found that low levels of dissolved oxygen, also known as hypoxia, can induce sex changes in embryonic fish, leading to an overabundance of males. As these predominately male fish mature, it is unlikely they will be able to reproduce in sufficient numbers to maintain sustainable populations, Wu says. Low oxygen levels also might reduce the quantity and quality of the eggs produced by female fish, diminishing their fertility, he adds.........

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March 24, 2006, 0:12 AM CT

What Happened to the Antimatter?

Researchers of the DZero collider detector collaboration at the Department of Energy's Fermi National Accelerator Laboratory have announced that their data on the properties of a subatomic particle, the B_s meson ("B sub s"), suggest that the particle oscillates between matter and antimatter in one of nature's fastest rapid-fire processes-more than 17 trillion times per second. Their findings may affect the current view of matter-antimatter asymmetry, and might also offer a first glimpse of the contributions of new physics, such as supersymmetry, to particle physics.

The DZero result, suggesting a preferred oscillation frequency between 17 and 21 times per picosecond (trillionth of a second), is described in a paper submitted to the journal, Physical Review Letters. The result, a measure of the oscillation or "mixing" frequency of the particle, has a confidence level of 90 percent, and so does not qualify as a discovery. Physicists have agreed that claims of a discovery must have a confidence level of 99.99995 percent, indicating a 99.99995 percent chance that the result can be reproduced. The data for the DZero result were culled from one inverse femtobarn of total collision data, or more than one billion events from Fermilab's Tevatron particle accelerator -- a milestone capitalizing on the significant luminosity improvements in the Tevatron. The DZero result also sets the stage for future results. Within the next month or so, the CDF collider detector collaboration at Fermilab expects to have a result with greater precision than the DZero result.........

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March 21, 2006, 9:52 PM CT

Metal Detector To Study Human Disease

Zinc may be a familiar dietary supplement to millions of health-conscious people, but it remains a mystery metal to researchers who study zinc's role in Alzheimer's disease, stroke and other health problems.

They are just beginning to fathom how the body keeps levels of zinc under the precise control that spells the difference between health and disease.

Scientists now have developed a biochemical metal detector to help crack the mystery. It is a biosensor that has yielded the first measurements of the tiny amounts of zinc ordinarily present inside living cells.

The study appears in the current issue of ACS Chemical Biology, the newest of 34 journals published by the American Chemical Society, the world's largest scientific organization.

It was conducted by Rebecca A. Bozym and Richard B. Thompson, Ph.D. of the department of biochemistry and molecular biology, University of Maryland School of Medicine, Baltimore, and Andrea K. Stoddard and Carol A. Fierke, Ph.D. of the Department of Chemistry, University of Michigan, Ann Arbor.

"The question of how much zinc is available in a cell has emerged at the forefront of chemical biology," Amy R. Barrios, Ph.D., of the University of Southern California, Los Angeles, wrote in an accompanying Point of View in ACS Chemical Biology.........

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March 20, 2006, 7:57 PM CT

A Powerful Chemical Analysis Tool

Physicists at JILA have designed and demonstrated a highly sensitive new tool for real-time analysis of the quantity, structure, and dynamics of a variety of atoms and molecules simultaneously, even in miniscule gas samples. The technology could provide unprecedented capabilities in a number of settings, such as chemistry laboratories, environmental monitoring stations, security sites screening for explosives or biochemical weapons, and medical offices where patients' breath is analyzed to monitor disease.

Described in the March 17 issue of Science,* the new technology is an adaptation of a conventional technique, cavity ring-down spectroscopy, for identifying chemicals based on their interactions with light. The JILA system uses an ultrafast laser-based "optical frequency comb" as both the light source and as a ruler for precisely measuring the a number of different colors of light after the interactions. The technology offers a novel combination of a broad range of frequencies (or bandwidth), high sensitivity, precision, and speed. A provisional patent application has been filed.

JILA is a joint institute of the National Institute of Standards and Technology (NIST), a non-regulatory agency of the U.S. Department of Commerce, and the University of Colorado at Boulder.........

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March 19, 2006, 8:16 PM CT

New Class Of Compounds Promise Better Drugs

By combining a common organic compound with a rare metal, a team of Brown University chemists has created a new class of molecules that have potentially important applications for the pharmaceutical, chemical and energy industries.

To create the mixture, researchers working in the laboratory of Dwight Sweigart, a Brown professor of chemistry, combined two compounds. One is hydroquinone, pale organic crystals critical for a number of biological processes as well as the manufacture of everything from skin bleaching creams to high-performance plastics. The other is the precious metal rhodium. The resulting reaction produced rhodium quinones.

"This mixture has marvelous properties," Sweigart said. "Rhodium quinones are very fast and efficient catalysts. They also have pores, or channels, that act like a sponge, giving them the ability to store gases. The secret is rhodium. It's the Superman of elements".

Rhodium is lighter than platinum, rarer than gold, and, at about $3,000 an ounce, the priciest of precious metals. The silvery white substance is prized as a potent, long-lasting catalyst and is used to concoct antifreeze, detergents and other industrial chemicals as well to make automotive catalytic converters, which cut down on air pollution. Rhodium is also the most reflective element on the periodic table and can be found in searchlights, dental mirrors, and giant microscopes known as synchotrons.........

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March 16, 2006, 10:59 PM CT

Green Chemistry

Using the unique properties of new nanometer-scale magnetic particles, scientists have for the first time separated for reuse two different catalysts from a multi-step chemical reaction done in a single vessel.

By combining the new magnetic separation process with traditional gravity-driven separation, the technique could lead to more efficient production of specialty chemicals - and a reduction in waste normally produced by separation processes. The research was reported March 13 in the online preview version of the journal Angewandte Chemie International Edition.

"We have developed a way to do multiple reactions in a single vessel while being able to recover the catalysts in pure form for reuse," explained Christopher W. Jones, an associate professor in the School of Chemical & Biomolecular Engineering at the Georgia Institute of Technology. "By doing the reactions in a single vessel, we can cut out two or three separation steps to provide both an economic advantage and an environmentally non-malignant process".

Separations using magnetic catalysts have been limited by a tendency of the nanoparticles to clump together because of their magnetic attraction for one another. The clumping dramatically reduces their catalytic activity.

To overcome this problem, the Georgia Tech scientists used nanometer-scale magnetic particles that are so small (5 to 20 nanometers in diameter) that they no longer exhibit a net magnetic attraction. But these superparamagnetic nanoparticles, developed by the research group of Z. John Zhang in Georgia Tech's School of Chemistry and Biochemistry, are attracted to an external magnetic source, providing a mechanism for separating them in pure form from the reaction vessel.........

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March 15, 2006, 8:56 PM CT

Atomsmay Have Heard About Three Musketeers

An international team of physicists has converted three normal atoms into a special new state of matter whose existence was proposed by Russian scientist Vitaly Efimov in 1970.

In this new state of matter, any two of the three atoms--in this case cesium atoms-- repel one another in close proximity. "But when you put three of them together, it turns out that they attract and form a new state," said Cheng Chin, an Assistant Professor in Physics at the University of Chicago.

Chin, along with 10 researchers led by Rudolf Grimm at the University of Innsbruck in Austria, report this development in the March 16 issue of the journal Nature. The paper describes the experiment in Grimm's laboratory where for the first time physicists were able to observe the Efimov state in a vacuum chamber at the ultracold temperature of a billionth of a degree above absolute zero (minus 459.6 degrees Fahrenheit).

This new state behaves like the Borromean ring, a symbol of three interlocking circles that has historical significance in Italy. The Borromean concept also exists in physics, chemistry and mathematics.

"This ring means that three objects are entangled. If you pick up any one of them, the other two will follow. However, if you cut one of them off, the other two will fall apart," Chin said. "There is something magic about this number of three."........

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March 15, 2006, 7:08 AM CT

Ultracold Atoms Produce Quantum Mix

Rice University physicist Randall Hulet will discuss breakthrough efforts to create a long-sought quantum superfluid at a press conference at 2:30 p.m. today at the American Physical Society's 2006 March Meeting.

In January, Hulet's laboratory published in the journal Science the observation of an elusive quantum state - a superfluid of fermions with mismatched numbers of dance partners. Despite more than 40 years of theoretical musings about what would occur in such a case, the result -- a cluster of matched pairs surrounded by a cloud of would-be dance partners -- was largely unexpected, and it has opened the door to several intriguing new avenues of investigation.

Hulet will discuss published findings and ongoing investigations today in room 334 of the Baltimore Convention Center.

Rice's experiments offer physicists a new window into two of the most intriguing and least understood phenomena in physics - superconductivity and superfluidity.

In the bizarre and rule-bound world of quantum physics, every tiny speck of matter has something called "spin" -- an intrinsic trait like eye color -- that cannot be changed and which dictates, very specifically, what other bits of matter the speck can share quantum space with. Because of their spins, fermions are the most antisocial of quantum particles. But when they do get together, fermion pairings enable such wondrous things as superconductivity and superfluidity.........

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March 15, 2006, 6:43 AM CT

chemical bonds with molecular wires to speed reactions

Using a chain of molecules as an infinitesimal lanyard to tug on a chemical bond about to break, Duke University chemists have found they can speed a complex chemical reaction.

Their unusual manipulative technique can reveal previously unknown details about the evolution of such two-step bond reactions, said assistant Duke chemistry professor Stephen Craig. It might ultimately aid efforts to develop new kinds of polymers that can "heal" themselves after tearing, he said.

Craig, current doctoral student Farrell Kersey and former graduate student Wayne Yount described their discoveries in a research paper published online Friday, March 3, 2006, in the Journal of the American Chemical Society (JACS). The work was funded by the National Science Foundation.

"We probed a reaction in which a bond was being made and a bond was being broken by pulling on the bond being broken with an atomic force microscope (AFM)," said Craig. An AFM detects forces or creates images of surfaces at molecular scales by mechanically probing with a flexible microscopic cantilevered tip.

In their experiments, Craig's group used an AFM tip to exert almost infinitesimally small tugs on a molecular complex made of pyridine and the metal palladium.

The scientists dangled the pyridine-palladium complex in space as if it were part of a molecular trapeze act, by attaching trapeze "wires" made of atomic chains of the molecule polyethylene glycol (PEG). One PEG chain connected the dangling pyridine-palladium to the AFM's tip. A separate PEG "wire" anchored the complex underneath onto an underlying surface substrate.........

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March 15, 2006, 6:33 AM CT

How Electrons Behave On Various Surfaces

Hrvoje Petek, University of Pittsburgh professor of physics and codirector of Pitt's Gertrude E. and John M. Petersen Institute of NanoScience and Engineering (PINSE), has published two papers in recent weeks that literally illuminate how electrons behave on various surfaces.

In the first paper, Petek and Miroslav Nyvlt of Charles University in Prague explored the properties of metals under intense light--a situation "where the classical physics of electron emission from metals emerges from its quantum roots," says Petek. They found that when light of a certain energy and intensity is shone onto a metal surface, a few electrons in the metal become stuck on the surface (that is, they are neither emitted from nor reabsorbed into the metal). As Petek puts it, the electrons are "in limbo."

These electrons undergo the process of "total internal reflection"--a process well known for light, but observed by Petek and Nyvlt for the first time in electrons.

These findings, reported in the March 3 issue of Physical Review Letters (PRL), could lead to the ability to transmit electrons, without scattering, over larger distances than previously possible. For example, electrons on the surface of carbon nanotubes could be excited to make "very small and very fast" transistors, Petek says.........

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