October 27, 2006, 9:26 PM CT

Vitamin C and Water Healthy for Plastics, Too

Two new laboratory breakthroughs are poised to dramatically improve how plastics are made by assembling molecular chains more quickly and with less waste. Using such environmentally friendly substances as vitamin C or pure water, the two approaches present attractive alternatives to the common plastic manufacturing technique called free radical polymerization (FRP).

"The methods both present novel and complementary ways to dramatically improve efficiency, product control, and cost for the polymer industry," said Andy Lovinger, the National Science Foundation program director who oversees funds for the two projects. "Each of these approaches could have a very significant impact on polymer manufacturing".

Plastics are polymers, long, potentially complex, molecule chains crafted from an array of smaller chemical units. Using FRP, chemical engineers can create the right plastic for a range of applications, such as a specific trim for a car door or soft foam for a pillow.

For some plastics, the building-block molecules do not easily link together. To surmount this problem, scientists from Carnegie Mellon University in Pittsburgh, Pa., devised a process called atom transfer radical polymerization (ATRP), which provides creative ways to coax the chemical subunits into chains. However, this method comes with certain costs, such as the need for a copper catalyst that can become unwanted waste.........

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October 27, 2006, 9:19 PM CT

How Oceans Emit Sulfur Into Atmosphere

Researchers have discovered a bacterial "switch gene" in two groups of microscopic plankton common in the oceans. The gene helps determine whether certain marine plankton convert a sulfur compound to one that rises into the atmosphere, where it can affect the earth's temperature, or remain in the sea, where it can be used as a nutrient.

"This new gene offers a powerful tool to study the question of how these plankton are involved with sulfur exchange between the ocean and atmosphere," said Mary Ann Moran, marine microbial ecologist at the University of Georgia. Moran and her colleagues published their findings in the Oct. 26, 2006, issue of the journal Science.

Much of the sulfur in the atmosphere comes from the surface of oceans, from a compound called dimethlysulfide, or DMS. Marine plankton control how much sulfur rises into the atmosphere by converting a compound called DMSP, or dimethylsulfoniopropionate, to DMS or to sulfur compounds that are not climatically active. Moran and her team discovered a gene that controls whether or not these sea drifters create DMS that rises into the air.

"Isolating and discovering a novel, keystone bacterium from the ocean first, and then sequencing its genome enabled this team to find the genes involved in the DMSP cycle," said Matthew Kane, program director in the National Science Foundation (NSF) Division of Molecular and Cellular Biosciences, which supported the research. "The research has revealed the previously hidden role that marine microbes play in the global sulfur cycle".........

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October 27, 2006, 4:33 AM CT

Cracking The Stellar Evolution

Using 3D models run on some of the fastest computers in the world, Laboratory physicists have created a mathematical code that cracks a mystery surrounding stellar evolution.

For years, physicists have theorized that low-mass stars (about one to two times the size of our sun) produce great amounts of helium 3 (³He). When they exhaust the hydrogen in their cores to become red giants, most of their makeup is ejected, substantially enriching the universe in this light isotope of helium.

This enrichment conflicts with the Big Bang predictions. Scientists theorized that stars destroy this ³He by assuming that nearly all stars were rapidly rotating, but even this failed to bring the evolution results into agreement with the Big Bang.

Now, by modeling a red giant with a fully 3D hydrodynamic code, LLNL researchers identified the mechanism of how and where low-mass stars destroy the ³He that they produce during evolution.

They found that ³He burning in a region just outside of the helium core, previously thought to be stable, creates conditions that drive this newly discovered mixing mechanism.

Bubbles of material, slightly enriched in hydrogen and substantially depleted in ³He, float to the surface of the star and are replaced by ³He-rich material for additional burning. In this way the stars destroy their excess ³He, without assuming any additional conditions (like rapid rotation).........

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October 26, 2006, 4:51 AM CT

Nuclear Receptors In Bee Genome

Susan Fahrbach, a Wake Forest University biologist, is among the more than 170 researchers who helped decode the honey bee genome. She contributed to the article on the bee genome sequence that appears in the Oct. 26 issue of Nature.

Her piece of the puzzle -- analyzing the nuclear hormone receptors found in the bee genome -- also appears in the current issue of Insect Molecular Biology.

The honey bee was chosen to have its genome sequenced because of its dual importance to agriculture and medicine. The well-known pollination activities of honey bees add billions of dollars of value to U.S. crops every year, but bees are also used in the laboratory to study issues related to human health such as immunity, longevity and diseases of the X chromosome. In addition, brain scientists are interested in the honey bee's complex social life and their ability to communicate the location of flowers to other members of the hive.

Fahrbach, Reynolds Professor of Developmental Neuroscience, and her co-researchers at Wake Forest and the University of Illinois, searched the genome sequence to find all of the nuclear receptors encoded in the bee genome. They found that the same nuclear receptors that control the development of the nervous system during the early.........

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October 24, 2006, 8:43 PM CT

A Supersolid Not Quite So Super?

A deceptively simple experiment, recently reported in the journal Science, has moved physics one step closer to explaining the odd behavior of supersolid helium. The unusual state of matter - in which a portion of the atoms are able to flow through a solid crystal with no resistance - was predicted as early as 1969 but not observed until recently.

In 2004, Eunsong Kim and Moses Chan from Penn State University published the first experimental evidence that the predicted behavior could actually be demonstrated in the laboratory. In the last two years, a flurry of papers attempted to clarify under what conditions the behavior emerges. So when Humphrey Maris, a professor of physics at Brown University, visited colleagues Satoshi Sasaki and Sebastien Balibar at l'Ecole Normale Superieure in Paris, they decided they needed to plan an experiment that could shed some new light on the problem.

"We were trying to think of an easy way to do something on superfluid solids," said Maris. "The idea of something flowing through something solid is pretty weird, isn't it? That's what we like about it".

Maris and company hatched an elegant plan that uses kitchen table physics to examine the behavior of this strange new state of matter. To understand how they probed the phenomenon, try this simple experiment. Fill a drinking straw with water and cover it with your finger. Place it in a glass of water. As long as your finger seals the straw, the water won't flow out into the cup. As soon as you release your finger, it does. The water doesn't flow out of the straw until you open a path that allows air to replace it.........

Posted by: Sarah      Permalink         Source

October 22, 2006, 8:23 PM CT

Subatomic Quick-change Artist

It's taken 19 long years of painstaking, high-precision experiments, but it's finally official: Physicists have announced the observation of a subatomic particle known as the Bs (pronounced "B sub s") meson switching between matter and antimatter states at a mind-boggling 3 trillion times per second.

The work could lead to a better understanding of the early universe, in which these particles were present in great abundance. It will also help physicists refine different theoretical models in high-energy physics.

Christoph Paus, associate professor of physics at MIT, led the analysis of years' worth of data from the world's highest-energy particle accelerator. Representing the 700-member team of the Collider Detector at Fermilab (CDF) collaboration, Paus presented the discovery to the scientific community Sept. 22 at the Fermi National Accelerator Laboratory in Illinois.

"The CDF result is an exquisite example of precision measurements extracting a small and subtle effect from nature," said Richard G. Milner, professor of physics and director of MIT's Laboratory for Nuclear Science (LNS). "The MIT group under the leadership of Christoph Paus, and with the strong support of the U.S. Department of Energy Office of High Energy Physics, the MIT Department of Physics and the MIT School of Science, constructed a key detector that was essential to this measurement".........

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October 22, 2006, 8:00 PM CT

Entanglement Of Atom Pairs

Physicists at the Commerce Department's National Institute of Standards and Technology (NIST) have taken a significant step toward transforming entanglement-an atomic-scale phenomenon described by Albert Einstein as "spooky action at a distance"-into a practical tool. They demonstrated a method for refining entangled atom pairs (a process called purification) so they can be more useful in quantum computers and communications systems, emerging technologies that exploit the unusual rules of quantum physics for pioneering applications such as "unbreakable" data encryption.

The NIST work, published in the Oct. 19, 2006, issue of Nature,* marks the first time atoms have been both entangled and subsequently purified; previously, this process had been carried out only with entangled photons (particles of light). The NIST demonstration also is the first time that researchers have been able to purify particles nondestructively. Direct measurement would destroy the delicate entangled state of atom pairs; the new experiment gets around this problem by entangling two pairs of atoms and measuring only one pair.

Entanglement is a curious property of quantum physics that links the condition and behavior of two or more particles, such as atoms or photons. Entanglement can occur spontaneously when two atoms interact. For the initial interaction, the atoms have to be in close proximity, but the entanglement may persist even if they are physically moved apart. The quality of the entanglement can be degraded by a number of environmental factors, such as fluctuating magnetic fields, so the process and the transport of entangled particles need to be tightly controlled in technological applications. The purification process implemented at NIST can clean up or remove any distortions or "noise" regardless of the source by processing two or more noisy entangled pairs to obtain one entangled pair of higher purity.........

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October 17, 2006, 9:35 PM CT

DNA computing targets West Nile Virus

Researchers say that they have developed a DNA-based computer that could lead to faster, more accurate tests for diagnosing West Nile Virus and bird flu. Representing the first "medium-scale integrated molecular circuit," it is the most powerful computing device of its type to date, they say.

The new technology could be used in the future, perhaps in 5 to 10 years, to develop instruments that can simultaneously diagnose and treat cancer, diabetes or other diseases, according to a team of scientists at Columbia University Medical Center in New York and the University of New Mexico, Albuquerque. Their study is scheduled to appear in the recent issue of the American Chemical Society's Nano Letters, a monthly peer-reviewed journal.

"This is a big step in DNA computing," says Joanne Macdonald, Ph.D., a virologist at Columbia University's Department of Medicine. Macdonald led the research team that developed MAYA-II (Molecular Array of YES and AND logic gates) ¯ a "computer" whose circuits consist of DNA instead of silicon. She likens the significance of the advance to the development of the earliest silicon chips. "The study shows that large-scale DNA computers are possible".

"These DNA computers won't compete with silicon computing in terms of speed, but their advantage is that they can be used in fluids, such as a sample of blood or in the body, and make decisions at the level of a single cell," says the researcher, whose work is funded by the National Science Foundation. Her main collaborators in this study were Milan Stojanovic, of Columbia University, and Darko Stefanovic, of the University of New Mexico.........

Posted by: Kevin      Permalink         Source

October 16, 2006, 10:21 PM CT

Chemistry To Predict The Dynamics Of Clotting

University of Chicago chemists have demonstrated for the first time how to use a simple laboratory model consisting of only a few chemical reactions to predict when and where blood clotting will occur. The scientists used microfluidics, a technique that allowed them to probe blood clotting on surfaces that mimic vascular damage on the micron scale, a unit of measurement much narrower than the diameter of a human hair.

Although scientists understand what occurs during many of the 80 individual chemical reactions involved in blood clotting, many questions about the dynamics of the entire reaction network remain. Rustem Ismagilov, Associate Professor in Chemistry at the University of Chicago, and graduate students Christian Kastrup, Matthew Runyon and Feng Shen have now developed a technique that will enable scientists to understand the rules governing complex biological reaction networks. They will detail their technique in the online early edition of the Oct. 16-20 issue of the Proceedings of the National Academy of Sciences.

Life and death literally depend on a finely tuned blood-clotting system. "Clotting has to occur at the right place at the right time," Ismagilov said. "A strong, rapid clotting response is essential to stop bleeding at a wound, but such a clotting response at the wrong spot can block blood vessels and can be life-threatening".........

Posted by: Sarah      Permalink         Source

October 12, 2006, 10:07 PM CT

A Ruler of Gold and DNA

Researchers from the U.S. Department Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have developed a ruler made of gold nanoparticles and DNA that can measure the smallest of life's phenomena, such as precisely where on a DNA strand a protein attaches itself.

The molecular ruler, detailed in the October premier issue of the journal Nature Nanotechnology, offers label-free and real-time measurement of a range of protein-DNA interactions at an extremely high resolution. As such, it promises to play a key role in the current push in biology to understand how genetic information flows from DNA to RNA to gene expression. Today, researchers involved in this research typically examine the final products of this chain of events by cataloging the expression levels of various genes and proteins.

The newly developed molecular ruler, however, can give researchers a much earlier glimpse into this process by measuring the initial protein-DNA binding interactions that unleash the flow of information which, in turn, sparks gene expression.

"We can use the ruler to look at this process much more upstream. We can measure the beginning stages of DNA-binding activities," says Fanqing Frank Chen, a scientist in Berkeley Lab's Life Sciences Division who was a member of the research team that, for the first time, used the molecular ruler to map protein-DNA interactions.........

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