February 20, 2007, 7:36 PM CT

Vanadium Won't Turn Down The Volume

esearchers at Carnegies Geophysical Laboratory have discovered a new type of phase transitiona change from one form to anotherin vanadium, a metal that is usually added to steel to make it harder and more durable. Under extremely high pressures, pure vanadium crystals change their shape but do not take up less space as a result, unlike most other elements that undergo phase transitions. The work appears in the February 23 issue of Physical Review Letters.

Led by High Pressure Collaborative Access Team (HPCAT) research scientist Yang Ding, the team* used a diamond anvil cell to subject vanadium crystals to pressures more than 600 thousand times higher than the atmospheric pressure at sea level (which is about one bar). Using the high-resolution HPCAT x-ray facility, the researchers were able to detect that the basic atomic packing units of vanadium crystals had changed from a cube to a rhombohedron, which resembles a cube whose sides have been squashed from squares into diamond shapes.

Trying to understand why high-pressure vanadium uniquely has the record-high superconducting temperature of all known elements inspired us to study high-pressure structure of vanadium," Ding said. We had no idea that we would discover a completely new type of phase transition"......... Posted by: Sarah      Read more         Source

February 15, 2007, 6:20 AM CT

DNA to detect hazardous uranium ions

Scientists at the University of Illinois at Urbana-Champaign have developed a simple, disposable sensor for detecting hazardous uranium ions, with sensitivity that rivals the performance of much more sophisticated laboratory instruments.

The sensor provides a fast, on-site test for assessing uranium contamination in the environment, and the effectiveness of remediation strategies, said Yi Lu, a chemistry professor at Illinois and senior author of a paper accepted for publication in the Proceedings of the National Academy of Sciences, and posted on its Web site.

A unique feature of our uranium sensor is that it contains a small piece of DNA, the same basic building blocks of our genes, said Lu, who also is a researcher at the universitys Beckman Institute for Advanced Science and Technology, and at the Center of Advanced Materials for the Purification of Water with Systems. Our sensor combines the high metal ion selectivity of catalytic DNA with the high sensitivity of fluorescence detection.

While most DNA is double stranded, the catalytic DNA Lus research group uses has a single strand region that can wrap around like a protein. In that single strand, the scientists fashion a specific binding site a kind of pocket that can only accommodate the metal ion of choice......... Posted by: Sarah      Read more         Source

February 15, 2007, 4:38 AM CT

Lsu Professor Resolves Einstein's Twin Paradox

Delaune Distinguished Professor of Electrical and Computer Engineering at LSU, recently resolved the twin paradox, known as one of the most enduring puzzles of modern-day physics.

First suggested by Albert Einstein more than 100 years ago, the paradox deals with the effects of time in the context of travel at near the speed of light. Einstein originally used the example of two clocks one motionless, one in transit. He stated that, due to the laws of physics, clocks being transported near the speed of light would move more slowly than clocks that remained stationary. In more recent times, the paradox has been described using the analogy of twins. If one twin is placed on a space shuttle and travels near the speed of light while the remaining twin remains earthbound, the unmoved twin would have aged dramatically in comparison to his interstellar sibling, as per the paradox.

If the twin aboard the spaceship went to the nearest star, which is 4.45 light years away at 86 percent of the speed of light, when he returned, he would have aged 5 years. But the earthbound twin would have aged more than 10 years! said Kak.

The fact that time slows down on moving objects has been documented and verified over the years through repeated experimentation. But, in the prior scenario, the paradox is that the earthbound twin is the one who would be considered to be in motion in relation to the sibling and therefore should be the one aging more slowly. Einstein and other researchers have attempted to resolve this problem before, but none of the formulas they presented proved satisfactory......... Posted by: Kevin      Read more         Source

February 6, 2007, 9:29 PM CT

Man-made Proteins Could Be More Useful

Scientists have constructed a protein out of amino acids not found in natural proteins, discovering that they can form a complex, stable structure that closely resembles a natural protein. Their findings could help researchers design drugs that look and act like real proteins but won't be degraded by enzymes or targeted by the immune system, as natural proteins are.

The researchers, led by Howard Hughes Medical Institute (HHMI) professor Alanna Schepartz, report their findings in the February 14, 2007, issue of the Journal of the American Chemical Society, published in advance online on January 19, 2007. Schepartz and her coauthors, Douglas Daniels, James Petersson, and Jade Qiu, are all at Yale University. A story in the February 5, 2007, issue of Chemical & Engineering News spotlighted the research.

As an HHMI professor, Schepartz received a $1 million grant to find ways to infuse undergraduate teaching with the excitement of research. Several of her HHMI undergraduates synthesized beta-amino acid monomers that were used to prepare the synthetic protein.

Schepartz and his colleagues built the short protein, or peptide, from ß-amino acids, which, eventhough they exist in cells, are never found in ribosomally produced proteins. ß-amino acids differ from the alpha-amino acids that compose natural proteins by the addition of a single chemical component-a methylene group-into the peptide backbone.........

Posted by: Sarah      Read more         Source

February 5, 2007, 9:39 PM CT

Hafnium Oxide Helps Make Chips Smaller And Faster

Intel and IBM have announced that they will use dramatically different materials to build smaller, faster transistors for their next generation of chips.

Traditionally fashioned out of silicon, transistors are simple on/off switches that process the ones and zeros of digital electronic data. The faster its transistors switch (known as the clock speed) the more efficient the chip. Making them smaller, cheaper, faster and more energy-efficient has helped the industry to stick to Intel's co-founder Gordon Moore prediction that the number of transistors on a chip would double roughly every two years.

Microprocessors now consist of millions of transistors connected together by specific patterns of copper wires. But using current silicon technology, there are limits to the continued fulfilment of 'Moore's Law'.

In transistors, current flows between two terminals, called 'source' and 'drain'. This current is controlled by the voltage at a third terminal, the 'gate' (see diagram). For a transistor to switch efficiently, the gate needs to be isolated from source and drain by a thin piece of insulating silica, known as the dielectric. As transistors shrink, so the silica gate insulator has thinned to just a few atomic layers. This allows quantum tunnelling of electrons, leading to current leakage across the dielectric, producing a lot of heat and poor chip performance.........

Posted by: Sarah      Read more         Source

February 5, 2007, 6:10 PM CT

Different Protein Building Blocks

Chemists at Yale have done what Mother Nature chose not to make a protein-like molecule out of non-natural building blocks, as per a report featured early online in the Journal of the American Chemical Society.

Nature uses alpha-amino acid building blocks to assemble the proteins that make life as we know it possible. Chemists at Yale now report evidence that nature could have used a different building block beta-amino acids and show that peptides assembled from beta-amino acids can fold into structures much like natural protein.

"The x-ray structure featured in the report shows a molecule that shares many of the structural characteristics of natural proteins," said principal author Alanna Schepartz, the Milton Harris '29 Ph.D. Professor of Chemistry at Yale and a Howard Hughes Medical Institute Professor. "Related studies show that the physical properties of the molecule are also remarkably similar to natural proteins. In other words, the beta-peptide assembly looks and acts a lot like a real protein".

The ability to mimic natural proteins makes beta-peptides powerful new tools for basic research and drug discovery. Like a taped recording, their greatest value may be in their difference from a live performance.

"Since beta-peptides are not processed in the cell like natural peptides or proteins, it may be possible in the future to design beta-peptides that perform better or in more locations than current protein drugs," said Schepartz. "They also may have unique properties as biomaterials".........

Posted by: Sarah      Read more         Source

February 2, 2007, 4:38 AM CT

Algae Toxin And The Fish-kill Mystery

A team of scientists from the Hollings Marine Laboratory in Charleston, S.C., has uncovered a subtle chemical pathway by which normally inoffensive algae, Pfiesteria piscicida, can suddenly start producing a lethal toxin. The discovery, reported last week in Environmental Science and Technology,* could resolve a long-standing mystery surrounding occasional mass fish kills on the East Coast.

Pfiesteria has been implicated for years in a series of otherwise unexplained episodes of mass fish death throughout its range from roughly Delaware to Alabama, especially in the Neuse River in North Carolina and the Chesapeake Bay. The single-cell organism can experience explosive growth resulting in algae blooms in coastal waters. While it has been suspected not only in fish kills but in incidents of human memory loss and other environmental and health-related effects, no one has ever conclusively identified the actual mechanism. Attempts to grow lethal Pfiesteria in the laboratory have had inconsistent results.

The Hollings Marine Laboratory is a joint institution of the National Oceanic and Atmospheric Administration (NOAA), the National Institute of Standards and Technology (NIST), the South Carolina Department of Natural Resources, the College of Charleston, and the Medical University of South Carolina (MUSC). Lead researcher Peter Moeller of NOAA suspected that the presence or absence of heavy metals might be the missing factor accounting for Pfiesteria's lethality, and put together a multidisciplinary research team to identify the actual toxin and the conditions under which it is produced.........

Posted by: Sarah      Read more         Source

January 11, 2007, 7:51 PM CT

Fixing The Nitrogen Balance

Scientists in the US have observed that, reassuringly, the global nitrogen cycles can be more easily balanced out than previously thought, as sources and sinks of usable nitrogen are geographically close and respond to each other in rapid feedback.

Conventional wisdom in biogeochemistry suggested that most of the nitrogen fixation in the oceans was going on in the Atlantic, where the supply of iron, mandatory by the nitrogenase enzyme, is more plentiful. However, the evidence also suggested that most of the loss of fixed nitrogen (denitrification) occurred in the Pacific. With such a vast distance between producers and consumers, the equilibrium between the two processes might have taken millennia to adjust to changes in environmental conditions, such as the current climate change.

Curtis Deutsch from the University of Washington at Seattle, together with colleagues from four other institutions across the US, has developed a new way of analysing the existing data on nitrogen cycles, based on the parameter P*, which describes the relative excess or lack of phosphate ions with respect to the predicted ratio between N and P consumption (normally 16:1).

Deutsch and his colleagues now conclude that inhabitants of the Pacific Ocean are responsible for around two thirds of the total nitrogen fixation that occurs annually in the oceans (estimated to be 140 million tons). The Atlantic contributes less than 20 per cent. Thus, the sources and sinks of usable nitrogen are geographically closer than anticipated. Furthermore, the analysis suggests that the supply of iron from the continents is not the limiting factor for nitrogenase activity. Instead, it looks as though nitrogen fixation is encouraged by a shortage of nitrate in a negative feedback loop, which stabilises the overall nitrogen balance of our planet.........

Posted by: William      Read more         Source

January 11, 2007, 5:04 AM CT

High school physics enrollment record high

More U.S. high-school students are taking physics than ever before, and the number of physics bachelor's degree recipients in the nation has increased 31 percent since 2000, as per new data presented today by the American Institute of Physics (AIP). In addition, physics bachelor's degree recipients are eight times more likely to go on to earn any kind of PhD than those with non-physics bachelor's, the new data show. Michael Neuschatz, senior research associate at AIP's Statistical Research Center, will present these new data in a physics education symposium entitled --"Overcoming Gravity"-- at this week's joint meeting of the American Association of Physics Teachers (AAPT) and the American Astronomical Society in Seattle.

"Good physics education is the backbone of a first-class workforce in science, technology, engineering, and mathematics," said Toufiq Hakim, AAPT's Executive Director, who organized the "Overcoming Gravity" session. "The future of U.S. economic competitiveness hinges on strong science education in our country".

Presenting new data that encourage this outlook, Neuschatz will show that enrollment in high school physics classes is up and likely to continue increasing. The data show more than 30 percent of high school seniors have taken physics classes, more than ever before. This percentage has been rising steadily since the mid-1980s.........

Posted by: Kevin      Read more         Source

January 9, 2007, 9:05 PM CT

Forest Fires Release Mercury

Forest fires release more mercury into the atmosphere than previously recognized, a multidisciplinary research project at the University of Michigan suggests.

The study, which has implications for forest management and global mercury pollution, was published online today (Jan. 9) in the journal Global Biogeochemical Cycles.

Doctoral student Abir Biswas, the paper's lead author, came up with the idea for the project when he was a student at U-M's Camp Davis Rocky Mountain Field Station near Jackson Hole, Wyoming. Wildfires were burning all around the station that summer, and smoke blanketed the camp. Around that time, Biswas happened to read a new scientific paper suggesting the possible role of fires in global mercury emissions.

"There I was, watching forest fires around our field camp, and it seemed like the ideal place to study the problem," he said.

The study Biswas read investigated mercury emissions from the combustion of foliage at locations around the USA and extrapolated to estimate mercury release during forest fires. "I'm interested in earth surface geochemistry so I wanted to approach the question differently," Biswas said.

Over the next two summers, under the direction of U-M professor Joel Blum, Biswas collected core samples of forest soil from burned and unburned areas, using sections of PVC pipe sharpened at one end to obtain the cylindrical samples. He and Blum also collaborated with U-M professor Gerald Keeler and former research scientist Bjorn Klaue to take air samples at Camp Davis-measuring mercury and trace metals over two summers-which provided the researchers with a picture of the atmospheric background on which the fires were superimposed.........

Posted by: Tyler      Read more         Source