April 1, 2007, 9:39 PM CT

The gigantic respiration of crystalline solids

Previously, only amorphous polymer materials approached such levels of performance. Conversely, these gigantic respiration and their respiration, which takes place at constant overall shape, is reversible. This discovery, of interest for numerous industrial applications, is reported in the journal Science on March 30, 2007.

The phenomenon of respiration is normally linked to life. Typically it is characterized by a reversible variation in the volume of a species under the effect of a stimulus (gas, pressure, temperature, irradiation, etc.). The volume of the lungs, for example, expands by 40 percent when breathing in. Organic matter, known for its flexibility, is well suited to this phenomenon. Conversely, inorganic matter is very often linked to the idea of rigidity and non-deformability. Scientists from the Institut Lavoisier (CNRS/Universit de Versailles Saint-Quentin-en-Yvelines) have recently demonstrated that the hybrid material (which combines both inorganic and organic entities) can be deformed in a reversible manner.

Within the framework of their studies on porous systems, Grard Frey and his team at the Institut Lavoisier have discovered a new family of trivalent metal dicarboxylates, which possess unprecedented respiration properties. Depending on the nature of the organic entity, the variation in volume when these solids are immersed in a solvent (water, methanol, etc.) can exceed 300 percent. Only some amorphous polymers approach this level of performance. However, unlike such polymers, the new solids are crystalline. The scientists determined their crystallographic structure in each state (solvated or not) and provided an explanation for the respiration mechanism, which takes place at constant overall shape, without any apparent rupture of bonds at the atomic level. The reversibility of the phenomenon is therefore facilitated......... Posted by: Sarah      Read more         Source

March 29, 2007, 4:44 AM CT

Tequila raw ingredient to treat colon diseases

Compounds derived from the blue agave, a fruit used to make tequila, shows promise in early laboratory studies as a natural, more effective way to deliver drugs to the colon than conventional drug-carriers, as per chemists at the University of Guadalajara in Mexico. The development could lead to improved therapys for ulcerative colitis, irritable bowel syndrome, cancer, Crohn's disease and other colon diseases, they say.

Drug delivery to the colon is an ongoing challenge to physicians. A number of drugs are destroyed by stomach acids before they've had a chance to reach the intestine, where they commonly are absorbed. Scientists have tried to circumvent this problem by inserting the drugs into carrier molecules that resist breakdown in the stomach but have had difficulty finding a suitable carrier compound.

The tequila compounds, a class of polysaccharides known as fructans, were developed by the researchers in Mexico into tiny microspheres that are capable of carrying existing drugs that are used to treat colon diseases. Because the compounds resist destruction in the stomach, they could allow more of the drugs to reach the colon intact and improve their effectiveness, the scientists say. Their study was presented today at the 233rd national meeting of the American Chemical Society......... Posted by: Sean      Read more         Source

March 27, 2007, 7:09 PM CT

Black Carbon Transported from Asia

More than three-quarters of the particulate pollution known as black carbon and transported at high altitudes over the West Coast during spring comes from Asia, as per a research team led by scientist V. Ramanathan of the Scripps Institution of Oceanography (SIO) in La Jolla, Calif. The material not only affects climate in Asia, it also carries consequences for the Pacific Ocean region that drives much of the climate around the world.

Climate researchers Ramanathan and Odelle Hadley are lead authors of a research paper appearing in the March 14 issue of the Journal of Geophysical Research. The research was funded by the National Science Foundation, the National Oceanic and Atmospheric Administration (NOAA) and the California Energy Commission (CEC).

"This study demonstrates that aerosols from all sources in East Asia significantly affect not only regional climate, but also affect climate across the 8,000 kilometers of the north Pacific Ocean," said Jay Fein, NSF program director for climate dynamics.

Transport of Asian black carbon, which is generated by automobile exhaust, agricultural burning and other sources, is heaviest in spring when cold Arctic fronts dip to lower latitudes and loft warmer air to higher altitudes. Worldwide transport of the aerosols keeps them at high altitudes for up to two weeks......... Posted by: Tyler      Read more         Source

March 25, 2007, 9:33 PM CT

Striking Gold With New Gold Catalysts

A University of California, Berkeley, chemist has found a mother lode of new and unique gold-catalyzed reactions by applying Einstein's theory of relativity to the rare and precious metal.

Catalysts are metals that speed up chemical reactions, such as when the platinum in a car's catalytic converter instantly converts polluting engine exhaust to oxygen, nitrogen, carbon dioxide and water.

Dean Toste, a UC Berkeley associate professor of chemistry, was one of the first chemists to experiment with gold as a catalyst. He opened the door for others interested in gold's versatility and in the potential to generate chemicals of interest for the chemical and pharmaceutical industry more efficiently and using less toxic precursors.

"This is a really hot area," Toste said. "If you look at the most-cited articles in the Journal of the American Chemical Society, a number of are about gold catalysis.

"With this class of gold catalysts, you can develop many unprecedented reactions that have never been seen before".

In a review article appearing in today's (March 22) issue of Nature, Toste discusses the new field and proposes a new theory for why gold has such unusual, and practical, catalytic properties. So far, the hypothesis has successfully predicted the behavior of gold catalysts in new chemical reactions......... Posted by: Sarah      Read more         Source

March 21, 2007, 9:56 PM CT

Tool To Track Atmospheric Carbon Dioxide

Researchers from NOAA's Earth System Research Laboratory announced recently a new tool to monitor changes in atmospheric carbon dioxide and other greenhouse gases by region and source. The tool, called CarbonTracker, will enable its users to evaluate the effectiveness of their efforts to reduce or store carbon emissions.

The online data framework distinguishes between changes in the natural carbon cycle and those occurring in human-produced fossil fuel emissions. It also provides verification for researchers using computer models to project future climate change. Potential users include corporations, cities, states and nations assessing their efforts to reduce or store fossil fuel emissions around the world.

"NOAA encourages science that adds benefit to society and the environment. CarbonTracker does both," said retired Navy Vice Admiral Conrad Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. "Increasingly, observations of the Earth are demonstrating a remarkable impact on our understanding of human and natural systems. We are transitioning this understanding gained from intensive research into operations that benefit the environment and the economy".

CarbonTracker distills an accurate assessment of greenhouse-gas increases or decreases. The resolution will increase to observe differences in concentration on finer geographical scales over time as data become available. Using the limited data that currently exist, the model can characterize emissions each month among U.S. regions, such as the West or the Southeast. As the observation network becomes denser, however, policymakers will be able to check the CarbonTracker Web site to compare emissions from urban centers. For instance, the resolution will be fine enough to determine the difference in net emissions from Sacramento as in comparison to San Francisco......... Posted by: Tyler      Read more         Source

March 15, 2007, 8:52 PM CT

Chemical breakthrough at FSU

"Build a better mousetrap," the saying goes, "and the world will beat a path to your door." In the complex field of organic chemistry, that path leads to Florida State University, where a newly developed substance could make the jobs of researchers throughout the world a little easier as they work to develop new drugs and other chemicals that benefit humanity.

Scientists from the Dudley Laboratory at FSU have invented a reagent a substance used in a chemical reaction to detect, measure, examine or produce other substances that can trap specific regions of complex molecules in such a way that those molecules can be released at a later time. This will allow researchers to perform complex experiments involving chemical synthesis much more easily and precisely.

"It isn't every day that one can put a new product on the market," said Gregory B. Dudley, an assistant professor of chemistry and biochemistry at FSU whose research lab bears his name.

"Even more exciting for me is the knowledge that scientific breakthroughs in biomedical research and various other areas of organic chemistry might be made possible as a result of this reagent," Dudley said.

The Sigma-Aldrich Chemical Company has licensed Dudley's patent-pending reagent from FSU and recently began marketing it to chemical research labs worldwide under the name "Bn-OPT" short for BeNzylOxyPyridinium Triflate. FSU will receive royalties from Sigma-Aldrich in the amount of 5 percent of net sales of the reagent......... Posted by: Sarah      Read more         Source

March 14, 2007, 10:32 PM CT

A Boost for Hydrogen Fuel Cell Research

The development of hydrogen fuel cells for vehicles, the ultimate green dream in transportation energy, is another step closer. Scientists with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and Argonne National Laboratory (ANL) have identified a new variation of a familiar platinum-nickel alloy that is far and away the most active oxygen-reducing catalyst ever reported.

The slow rate of oxygen-reduction catalysis on the cathode - a fuel cell's positively charged electrode - has been a primary factor hindering development of the polymer electrolyte membrane (PEM) fuel cells favored for use in vehicles powered by hydrogen.

"The existing limitations facing PEM fuel cell technology applications in the transportation sector could be eliminated with the development of stable cathode catalysts with several orders of magnitude increase in activity over today's state-of-the-art catalysts, and that is what our discovery has the potential to provide," said Vojislav Stamenkovic, a scientist with dual appointments in the Materials Sciences Division of both Berkeley Lab and Argonne.

Stamenkovic and Argonne senior scientist Nenad Markovic are the corresponding authors of a study whose results are now available online from the journal Science. The paper, entitled Improved Oxygen Reduction Activity on Pt3Ni(111) via Increased Surface Site Availability, reports a platinum-nickel alloy that increased the catalytic activity of a fuel cell cathode by an astonishing 90-fold over the platinum-carbon cathode catalysts used today......... Posted by: Sarah      Read more         Source

March 5, 2007, 4:15 PM CT

Designer Molecule to Clean Up Fluorocarbons

The chemical bond between carbon and fluorine is one of the strongest in nature, and has been both a blessing and a curse in the complex history of fluorocarbons. Now, in a powerful demonstration of the relatively new field of "computational chemistry," scientists at the National Institute of Standards and Technology (NIST) and the Interdisciplinary Network of Emerging Science and Technology group (INEST, sponsored by Philip Morris USA) have designed-in a computer-a wholly theoretical molecule to pull the fluorine out of fluorocarbons.*.

At sea level, the strong C-F bond makes fluorocarbons thermally and chemically stable. As a result, fluorocarbons have been used in a number of commercial applications including refrigerants, pesticides and non-stick coatings. In the upper atmosphere, however, high-energy photons and highly reactive ozone molecules can break apart fluorocarbons, with the well-known consequence of a depleted ozone layer and increased ultraviolet radiation at ground level. A determined chemist can break down fluorocarbons at ground level with certain organometallic compounds, but the reactions take a long time at very high temperatures. Other known reagents are both highly toxic and inefficient, so chemists have been searching for an economical and environmentally friendly method to dispose of fluorocarbons......... Posted by: Sarah      Read more         Source

February 26, 2007, 7:13 PM CT

Atomic Movements And Pharmaceuticals

Chemists at the University of Liverpool have designed a unique structure to capture the movement of atoms which may impact on future designs of pharmaceuticals.

The research, funded by the Engineering and Physical Sciences Research Council (EPSRC), will further understanding of how to control chemical reactions and will influence improvements in a range of important processes from the design of biopharmaceuticals to the engineering of new catalysts, enabling scientists, for example, to develop products in more environmentally friendly ways.

The Liverpool team created a porous crystal which has 'walls' of atoms and cavities which act as containers for molecules. They used this crystal to accommodate a set of molecules as they took part in a chemical reaction similar to reactions by enzymes and proteins to regulate and keep alive living systems.

The crystal was put into a powerful X-ray diffraction machine at Daresbury laboratory, Warrington. This allowed researchers to pinpoint precisely the positions of individual atoms, providing snapshots of their movement. Because the reaction was carried out within the cavities of the crystal, the team was able to locate the positions of the atoms both before and after the reaction. This is the first time that the positions of atoms both at the beginning and the end of a chemical process have been seen......... Posted by: Sarah      Read more         Source

February 22, 2007, 10:14 PM CT

New Hydrogen Fuel System

Northern Nevada energy consumers can be excused if they have a sense of "sticker shock" when their power bills come due following the holiday season. Or, that they have a feeling of powerlessness as the price of gasoline climbs to $3 per gallon.

They wonder: will the days of the $1 tank of gas ever return?

Thanks to research done by a University of Nevada, Reno professor in the area of hydrogen energy generation, soaring power bills could become a thing of the past. And, finding a power source for your car that costs as little as $1 per gallon could also soon become a welcome reality.

Manoranjan Misra, professor of materials science and engineering, recently received a $3 million research grant from the U.S. Department of Energy to continue his groundbreaking work in various forms of renewable energy. Misra's current project focuses on harnessing photoactive material from the sun to generate hydrogen. Hydrogen is one of the cleanest forms of energy, and studies have shown that it is 33 percent more efficient than liquid fuels.

Northern Nevada, with its unusually sunny weather with more than 300 sunny days per year could become the perfect hub to generate hydrogen energy, as per Misra.

"We can utilize this great energy resource to our advantage to produce hydrogen," Misra said. "We are uniquely positioned in Northern Nevada, as the average energy from the sun is around one kilowatt per square meter area. In Reno it is much higher than that. Because it is so bright and sunny here in Reno, we have in a number of ways the perfect location for photo-hydrogen generation"......... Posted by: Sarah      Read more         Source