January 29, 2008, 9:47 PM CT

Lithium and Beryllium No Longer "Lack Chemistry"

Even though the lightest known metals in the universe, lithium (Li) and beryllium (Be), do not bind to one another under normal atmospheric or ambient pressure, an interdisciplinary team of Cornell researchers predicts in the Jan. 24 issue of Nature that Li and Be will bond under higher levels of pressure and form stable Li-Be alloys that may be capable of superconductivity. Superconductivity is the flow of electricity with zero resistance.

The Inorganic, Bioinorganic and Organometallic Chemistry program at the National Science Foundation (NSF) supported the research because little work had been done to predict the properties of metals under high pressure.

"We observed that chemists working on inorganic compounds and inorganic reactions under high pressure were interested in the predictions and felt it would stimulate useful interactions between theorists and experimentalists," said NSF Program Manager Michael Clarke.

Of the four stable Li-Be alloys predicted by the scientists' computational study, the alloy with the ratio of one Li atom to one Be atom (LiBe) shows the greatest potential for superconducting applications.

A most unexpected finding in the study is the predicted existence of two-dimensional electron gas layers within a tightly compressed three-dimensional LiBe compound......... Posted by: Sarah      Read more         Source

January 29, 2008, 9:43 PM CT

Magnetism loses under pressure

Washington, D.C. Researchers have discovered that the magnetic strength of magnetitethe most abundant magnetic mineral on Earthdeclines drastically when put under pressure. Scientists from the Carnegie Institutions Geophysical Laboratory, together with colleagues at the Advanced Photon Source of Argonne National Laboratory, have observed that when magnetite is subjected to pressures between 120,000 and 160,000 times atmospheric pressure its magnetic strength declines by half. They discovered that the change is due to what is called electron spin pairing.

Magnetism comes from unpaired electrons in magnetic materials. The strength of a magnet is a result of the spin of unpaired electrons and how the spins of different electrons are aligned with one another. This research showed that the drop in magnetism was due to a decrease in the number of unpaired electrons.

Magnetite is found in small quantities in certain bacteria, in brains of some birds and insects, and even in humans, commented Yang Ding, the studys lead author with the Carnegie-led High-Pressure Synergetic Consortium. Early navigators used it to find the magnetic North Pole and birds use it for their navigation. And now it is used in nanotechnology. There is intense scientific interest in its properties. Understanding the behavior of magnetite is difficult because the strong interaction among its electrons complicates its electronic structure and magnetic properties......... Posted by: Sarah      Read more         Source

January 24, 2008, 11:00 PM CT

When accounting for the global nitrogen budget, don't forget fish

Like bank accounts, the nutrient cycles that influence the natural world are regulated by inputs and outputs. If a routine withdrawal is overlooked, balance sheets become inaccurate. Over time, overlooked deductions can undermine our ability to understand and manage ecological systems.

Recent research by the Universite de Montreal (Canada) and the Cary Institute of Ecosystem Studies (Millbrook, New York) has revealed an important, but seldom accounted for, withdrawal in the global nitrogen cycle: commercial fisheries. Results, published as the cover story in the recent issue of Nature Geoscience, highlight the role that fisheries play in removing nitrogen from coastal oceans.

Nitrogen is essential to plant and animal life; however, it is possible to have too much of a good thing. During the past century, a range of human activities have increased nitrogen inputs to coastal waters. Fertilizer run-off is the best documented and most significant source of terrestrial nitrogen pollution. Nitrogen-rich fertilizer applied to farmland eventually makes its way into coastal waters via a network of streams and rivers.

Research spearheaded by Roxane Maranger (Universite de Montreal) and Nina Caraco (Cary Institute) demonstrates that commercial fisheries play an important but declining role in removing terrestrial nitrogen from coastal waters. Accounting for this withdrawal is crucial; terrestrial-derived nitrogen can stimulate coastal phytoplankton growth, leading to eutrophication. Typically typically eutrophic waters are characterized by reduced dissolved oxygen, decreased biodiversity, and species composition shifts......... Posted by: Tyler      Read more         Source

January 14, 2008, 4:25 PM CT

From the Journal of Biological Chemistry

COX-2 inhibitors like Celecoxib have come under scrutiny lately due to adverse cardiovascular side-effects stemming from COX-2 reduction. In both fruit fly and rat models, scientists reveal another adverse effect of Celecoxib; this drug can induce arrhythmia. More interestingly, this effect is independent of the COX-2 enzyme.

Satpal Singh and his colleagues tested various Celecoxib doses on the heart rate of Drosophila, a good model for human cardiac pharmacology. To their surprise, administering 3 m Celecoxib (not much higher than the plasma levels in humans taking the drug) reduced heart rate and increased beating irregularities, while 30 m was enough to stop the heart within a minute.

The surprise arises from the fact that Drosophila do not have COX-2 enzymes. Rather, Celecoxib could directly inhibit the potassium channels that help generate the electric current that drives heartbeat.

The scientists could achieve similar heart-stopping results in rat cardiac cells, whereas aspirin, another potent COX-2 inhibitor, had no effect, confirming that another mechanism is at work. The drug also inhibited rat and human potassium channels expressed in a human cell line.

Singh and his colleagues point out that since these arrhythmia effects bypass COX-2, it is unclear if other COX-2 inhibitors would yield similar results. They also stress it is too early to speculate on human effects, eventhough their results suggest Drosophila are a valuable tool to investigate other COX-2 drugs......... Posted by: Sarah      Read more         Source

January 14, 2008, 3:39 PM CT

New buffer resists pH change

Scientists at the University of Illinois have found a simple solution to a problem that has plagued researchers for decades: the tendency of chemical buffers used to maintain the pH of laboratory samples to lose their efficacy as the samples are cooled. The research team, headed by chemistry professor Yi Lu, developed a method to formulate a buffer that maintains a desired pH at a range of low temperatures.

The study appears this month in Chemical Communications.

Researchers have known since the 1930s that the pH of chemical buffers that are used to maintain the pH of lab samples can change as those samples are cooled, with some buffers raising and others lowering pH in the cooling process.

Freezing is a standard method for extending the shelf life of biological specimens and pharmaceuticals, and biological samples are routinely cooled to slow chemical reactions in some experiments. Even tiny changes in the acidity or alkalinity of a sample can influence its properties, Lu said.

"We like to freeze proteins, nucleic acids, pharmaceutical drugs and other biomolecules to keep them a long time and to study them more readily under very low temperatures using different spectroscopic techniques and X-ray crystallography," Lu said. "But when the pH changes at low temperature, the sample integrity can change"......... Posted by: Sarah      Read more         Source

December 20, 2007, 8:49 PM CT

About Methane Bubbling Up From the Ocean Floor

Methane, a potent greenhouse gas, is emitted in great quantities as bubbles from seeps on the ocean floor near Santa Barbara. About half of these bubbles dissolve into the ocean, but the fate of this dissolved methane remains uncertain. Scientists at the University of California, Santa Barbara have discovered that only one percent of this dissolved methane escapes into the air -- good news for the Earth's atmosphere.

Coal Oil Point (COP), one of the world's largest and best studied seep regions, is located along the northern margin of the Santa Barbara Channel. Thousands of seep fields exist in the ocean bottom around the world, as per David Valentine, associate professor of Earth Science at UC Santa Barbara. Valentine along with other members of UCSB's seeps group studied the plume of methane bubbles that flows from the seeps at COP.

Their results will soon be published as the cover story in Volume 34 of Geophysical Research Letters. This research effort is the first time that the gas that dissolves and moves away from COP, the plume, has been studied.

The amount of methane release from COP seeps is around two million cubic feet per day, as per Valentine. About 100 barrels of oil oozes out of this area as well. Methane warms the Earth 23 times more than carbon dioxide when averaged over a century. Thus the fate of the methane bubbles from the seeps is an important environmental question......... Posted by: Tyler      Read more         Source

December 18, 2007, 8:14 PM CT

Powerful carbon-based electronics

Bypassing decades-old conventions in making computer chips, Princeton engineers developed a novel way to replace silicon with carbon on large surfaces, clearing the way for new generations of faster, more powerful cell phones, computers and other electronics.

The electronics industry has pushed the capabilities of silicon -- the material at the heart of all computer chips -- to its limit, and one intriguing replacement has been carbon, said Stephen Chou, professor of electrical engineering. A material called graphene -- a single layer of carbon atoms arranged in a honeycomb lattice -- could allow electronics to process information and produce radio transmissions 10 times better than silicon-based devices.

Until now, however, switching from silicon to carbon has not been possible because technologists believed they needed graphene material in the same form as the silicon used to make chips: a single crystal of material eight or 12-inches wide. The largest single-crystal graphene sheets made to date have been no wider than a couple millimeters, not big enough for a single chip. Chou and scientists in his lab realized that a big graphene wafer is not necessary, as long they could place small crystals of graphene only in the active areas of the chip. They developed a novel method to achieve this goal and demonstrated it by making high-performance working graphene transistors......... Posted by: Sarah      Read more         Source

December 12, 2007, 9:50 PM CT

Device Generates and Traps Rare Ultracold Molecules

Physicists at the University of Rochester have combined an atom-chiller with a molecule trap, creating for the first time a device that can generate and trap huge numbers of elusive-yet-valuable ultracold polar molecules.

Researchers believe ultracold polar molecules will allow them to create exotic artificial crystals and stable quantum computers.

"The neat thing about this technology is that it's a very simple, but highly efficient method," says Jan Kleinert, a doctoral physics student at the University of Rochester and designer of the new device. "It lets us produce huge quantities of these ultracold polar molecules, which opens so a number of doors for us".

The Thin WIre electroStatic Trap, or TWIST, is the first electrostatic polar molecule trap that works simultaneously with a magneto-optical atom trap. This means Kleinert can use the lasers of the magneto-optical trap, or MOT, to chill atoms to just a few millionths of a degree above absolute zero, then force the atoms to group into molecules, and instantaneously hold them in place with the electrostatic TWIST trap.

Traditionally, a complex process of creating and trapping is mandatory to produce these molecules, akin to repeatedly emptying and refilling the ice cube trays in your freezer, says Kleinert. A MOT with a TWIST, however, can create and store the chilled molecules in one place, instantly-more like a refrigerator with an automatic icemaker......... Posted by: Sarah      Read more         Source

December 10, 2007, 10:56 PM CT

Food source threatened by carbon dioxide

Carbon dioxide increasing in the atmosphere may affect the microbial life in the sea, which could have an impact on a major food source, warned Dr Ian Joint at a Science Media Centre press briefing today.

Dr Joint is sequencing the DNA of different ocean bacteria to find out how they will respond to an increase in carbon dioxide. So far from one experiment we have sequenced 300 million bases of DNA, about one tenth the size of the human genome. We are analyzing this ocean genome to see if changes might affect the productivity of the sea.

Worldwide, fish from the sea provide nearly a fifth of the animal protein eaten by man. If microscopic plants that fish eat are affected by carbon dioxide, this may deplete a major food source.

Bacteria still control the world said Dr Joint from Plymouth Marine Laboratory. They ensure that the planet is fertile and that toxic materials do not accumulate. The carbon dioxide produced by humans is turning the oceans into weak acids. This century, the seas will be more acidic than they have been for 20 million years.

There are a number of millions of different bacteria in the ocean. They control the cycling of oxygen, carbon, nitrogen and sulphur; microbes in the sea generate half of the oxygen produced globally every year. So the atmosphere could also be affected by ocean acidification. Bacteria made the earth suitable for animals by producing oxygen nearly 2 billion years ago. We want to find out if human activities will have a major impact on microbial life in the seas and if this is likely to be a problem for mankind in the future......... Posted by: Sarah      Read more         Source

December 4, 2007, 10:20 PM CT

Research On Hydrogen Storage

Research on hydrogen-fueled cars may be one step closer to application thanks to a new form of hydride discovered by researchers at the ESRF. The material, lithium borohydride, is a promising energy storage system: it contains 18 weight percents of hydrogen, which makes it attractive for use in hydrogen-fueled cars. Its drawback is that it only releases hydrogen at quite high temperatures (above 300 degrees C). The team at the ESRF has found a new form of the compound that could possibly release hydrogen in mild conditions. This discovery, completely unexpected from the point of view of theoretical predictions, is published recently as a Very Important Paper in Angewandte Chemie.

Atomative industry hydrogen as a perspective energy carrier. If a good hydrogen strorage material will be developed, the petrol in cars can be replaced by clean hydrogen energy. Five kilograms of hydrogen would take you as far as twenty liters of petrol. Today there are several compounds of interest, which are known to either store relatively large amounts of hydrogen or release it easily, but none do both in a way suitable for practical application.

Scientists at the Swiss-Norwegian experimental stations (beamlines) at the ESRF are currently studying several compounds of light elements with hydrogen and the different forms they take at different pressure and temperature. Lithium borohydride, LiBH4, is one of the compounds they study as it has a high weight content of hydrogen (18%). The new form of this compound, which researchers have just discovered, is promising because it appears to be unstable. Until......... Posted by: Sarah      Read more         Source