September 23, 2007, 10:44 AM CT

Palladium and platinum an easier find

Finding uses for palladium and platinum--rare precious metals coveted by the automobile, chemical, and pharmaceutical industries as catalysts in chemical reactions-proves easier than finding the scarce materials themselves.

Detection involves expensive instruments operated by highly trained chemists that take days to return results. But chemists at the University of Pittsburgh have unearthed a fast, easy, and inexpensive method that could help in the discovery of palladium/platinum deposits and streamline the production of pharmaceuticals. The research will be published online Sept. 21 in the Journal of the American Chemical Society.

The new method was developed in the laboratory of Kazunori Koide (Ko-ee-deh), a chemistry professor in Pitt's School of Arts and Sciences. It relies on a colorless fluorescein-based solution (similar to that used to find blood residue at crime scenes) that--under a simple hand-held ultraviolet lamp--glows green when it comes in contact with even minute amounts of palladium and platinum, which coexist in nature. The process takes approximately one hour as opposed to the effective but complex and days-long analysis currently employed in the mining and pharmaceutical industries, Koide explained. Moreover, the Pitt team's method can accommodate hundreds of samples at once whereas current technology analyzes samples only one at a time, Koide said......... Posted by: Sarah      Read more         Source

September 18, 2007, 5:01 AM CT

Changing concepts on neutron's electrical properties

For two generations of physicists, it has been a standard belief that the neutron, an electrically neutral elementary particle and a primary component of an atom, actually carries a positive charge at its center and an offsetting negative charge at its outer edge.

The notion was first put forth in 1947 by Enrico Fermi, a Nobel laureate noted for his role in developing the first nuclear reactor. But new research by a University of Washington physicist shows the neutron's charge is not quite as simple as Fermi believed.

Using precise data recently gathered at three different laboratories and some new theoretical tools, Gerald A. Miller, a UW physics professor, has observed that the neutron has a negative charge both in its inner core and its outer edge, with a positive charge sandwiched in between to make the particle electrically neutral.

"Nobody realized this was the case," Miller said. "It is significant because it is a clear fact of nature that we didn't know before. Now we know it".

The discovery changes scientific understanding of how neutrons interact with negatively charged electrons and positively charged protons. Specifically, it has implications for understanding the strong force, one of the four fundamental forces of nature (the others are the weak force, electromagnetism and gravity)......... Posted by: Sarah      Read more         Source

September 17, 2007, 5:07 AM CT

The Origin Of Soil-scented Geosmin

Brown University chemists have found the origins of an odor - the sweet smell of fresh dirt. In Nature Chemical Biology, the Brown team shows that the protein that makes geosmin - source of the good earth scent - has two similar but distinct halves, each playing a critical role in making this organic compound.

"Everyone is familiar with the wonderful smell of warm earth," said David Cane, professor of chemistry at Brown who oversaw the research. "Now we know precisely how it is made".

Geosmin, which literally translates to "earth smell," was scientifically identified more than 100 years ago. In soil, bacteria produce the chemical compound. In water, blue-green algae make it. Along with the pleasant scent of warm, moist soil, geosmin is also responsible for the muddy "off" taste in some drinking water. That is why the substance is of interest to water purification experts and even vintners, who want to keep the non-malignant but pungent substance out of their wine.

Until recently, researchers knew little about how geosmin is made. Then, a few years ago, Cane found the gene responsible for geosmin formation in Streptomyces coelicolor, a strain of plant-munching bacteria found in soil. Last year, the team discovered that a single protein converts farnesyl diphosphate to geosmin......... Posted by: Sarah      Read more         Source

Thu, 13 Sep 2007 03:50:02 GMT

Molecule of the Month: Citrate Synthase

Your body burns up a lot of food every day. However, cells don’t burn food like a fireplace. Instead, food molecules are combined with oxygen molecules one-by-one, in many carefully controlled steps. In this way, the energy that is released can be captured in convenient forms, like ATP or NADH, which are then used elsewhere to power essential cellular functions. Our cells get most of their energy from a long series of reactions that combine oxygen and glucose, forming carbon dioxide and water, and creating lots of ATP and NADH in the process.

Citrate synthase is a central enzyme in this process of sugar oxidation. It is the first step of the citric acid cycle, also known as the Krebs cycle. Glucose has previously been broken into several pieces by glycolysis, releasing two carbon atoms as carbon dioxide and leaving the rest as two molecules of acetate, carried in an activated form on special cofactor molecules. In the citric acid cycle, these remaining carbon atoms are fully oxidized to form carbon dioxide. Citrate synthase starts this process by taking the molecules of acetate and attaching them to oxaloacetate, which acts as a convenient handle as the carbon atoms are passed from enzyme to enzyme in the citric acid cycle.

More info by David Goodsell at the PDB, here. Posted by: PhilipJ      Read more     Source

September 10, 2007, 10:04 PM CT

Tiny Tubes and Rods as Catalysts

Researchers at the U.S. Department of Energy's Brookhaven National Laboratory have developed new ways to make or modify nanorods and nanotubes of titanium oxide, a material used in a variety of industrial and medical applications. The methods and new titanium oxide materials may lead to improved catalysts for hydrogen production, more efficient solar cells, and more protective sunscreens. The research is published in two papers now available online, one in Advanced Materials (August 22, 2007), and the other in the Journal of Physical Chemistry.

A number of researchers have explored ways to improve the light-absorbing capability of titanium oxide, for example, by "doping" the material with added metals. Han and his colleagues took a new approach. They enhanced the material's light-absorption capability by simply introducing nanocavities, completely enclosed pockets measuring billionths of a meter within the 100-nanometer-diameter solid titanium oxide rods.

The resulting nanocavity-filled titanium oxide nanorods were 25 percent more efficient at absorbing certain wavelengths of ultraviolet A (UVA) and ultraviolet B (UVB) solar radiation than titanium oxide without nanocavities.

"Our research demonstrates that titanium oxide nanorods with nanocavities can dramatically improve the absorption of UVA and UVB solar radiation, and thus are ideal new materials for sunscreen," Han said......... Posted by: Sarah      Read more         Source

August 27, 2007, 8:24 PM CT

Perfecting hydrogen-generating technology

Scientists at Purdue University have further developed a technology that could represent a pollution-free energy source for a range of potential applications, from golf carts to submarines and cars to emergency portable generators.

The technology produces hydrogen by adding water to an alloy of aluminum and gallium. When water is added to the alloy, the aluminum splits water by attracting oxygen, liberating hydrogen in the process. The Purdue scientists are in the process of developing a method to create particles of the alloy that could be placed in a tank to react with water and produce hydrogen on demand.

The gallium is a critical component because it hinders the formation of an aluminum oxide skin normally created on aluminum's surface after bonding with oxygen, a process called oxidation. This skin commonly acts as a barrier and prevents oxygen from reacting with aluminum. Reducing the skin's protective properties allows the reaction to continue until all of the aluminum is used to generate hydrogen, said Jerry Woodall, a distinguished professor of electrical and computer engineering at Purdue who invented the process.

Since the technology was first announced in May, scientists have developed an improved form of the alloy that contains a higher concentration of aluminum......... Posted by: Sarah      Read more         Source

August 26, 2007, 10:55 AM CT

Toxic Byproducts of Carbon Nanotube Manufacturing

A new analysis of by-products discharged to the environment during production of carbon nanotubes (CNTs) -- expected to become the basis of multibillion-dollar industries in the 21st Century -- has identified cancer-causing compounds, air pollutants, and other substances of concern, scientists reported here today at the 234th national meeting of the American Chemical Society.

Co-author of study Desiree L. Plata and his colleagues described their work as "totally new," noting that past analyses of the environmental impact of the emerging nanomaterials industry have been based on the toxicity of ingredients used in the recipes, rather than the actual pollutants formed during CNT manufacture. While expressing concern about the possible health and environmental effects of nanotechnology by-products, Plata said the new data may be crucial as the nanotechnology industry seeks to avoid the kind of unanticipated health and environmental problems that have accompanied emergence of other new technology.

Scientists said, for instance, that they foresee developing, in collaboration with the CNT industry, "green chemical" reactions and filtration systems to substitute for those with potentially hazardous by-products and other ways of manufacturing carbon nanotubes that minimize potentially adverse impacts......... Posted by: Kevin      Read more         Source

August 25, 2007, 7:16 AM CT

Explosive crystal

Known to the alchemists and long used as a detonator to set off dynamite-mercury fulminate has a checkered past. Now, more than 300 years after the discovery of this explosive compound, German scientists have been able to characterize its crystal structure and thus finally reveal the molecular structure of mercury fulminate. As Wolfgang Beck, Thomas Klapotke and their team report in the journal ZAAC - Journal of Inorganic and General Chemistry, the orthorhombic crystals consist of separate, nearly linear Hg(CNO)2 molecules.

The alchemists of the seventeenth century were already aware that mixtures of "spiritus vini" (ethanol) and mercury in "aqua fortis" (nitric acid) made for an explosive brew. In his book Laboratorium Chymicum, Johann Kunckel von Lowenstern describes the vigorous reaction of mercury nitrate with alcohol to form mercury fulminate (Hg(CNO)2). In 1799, the English chemist Edward Howard isolated the compound by chance, which was produced a sensation in the nascent scientific field of chemistry.

Mercury fulminate is very sensitive to shock, friction, and sparks. It explosively decomposes to form mercury, carbon monoxide, and nitrogen. This explosive power was used extensively: Alfred Nobel put mercury fulminate into blasting caps for detonating dynamite. This relatively safe new detonator was what allowed for the huge success of dynamite. In Gera number of alone, the annual production of mercury fulminate in the early 20th century reached about 100,000 Kg......... Posted by: Sarah      Read more         Source

August 21, 2007, 6:26 PM CT

Hydrogen For Tomorrow's Vehicles

Hydrogen may prove to be the fuel of the future in powering the effi cient, eco-friendly fuel cell vehicles of tomorrow. Developing a method to safely store, dispense and easily "refuel" the vehicle's storage material with hydrogen has baffl ed scientists for years. However, a new and attractive storage medium being developed by Pacific Northwest National Laboratory researchers may provide the "power of pellets" to fuel future transportation needs.

The Department of Energy's Chemical Hydrogen Storage Center of Excellence is investigating a hydrogen storage medium that holds promise in meeting long-term targets for transportation use. As part of the center, PNNL researchers are using solid ammonia borane, or AB, compressed into small pellets to serve as a hydrogen storage material. Each milliliter of AB weighs about three-quarters of a gram and harbors up to 1.8 liters of hydrogen. Scientists expect that a fuel system using small AB pellets will occupy less space and be lighter in weight than systems using pressurized hydrogen gas, thus enabling fuel cell vehicles to have room, range and performance comparable to today's automobiles.

"With this new understanding and our improved methods in working with ammonia borane," said PNNL scientist Dave Heldebrant, "we're making positive strides in developing a viable storage medium to provide reliable, environmentally friendly hydrogen power generation for future transportation needs"......... Posted by: Sarah      Read more         Source

August 21, 2007, 5:29 PM CT

More Cheaper Hydrogen

A new class of catalysts created at the U.S. Department of Energy's Argonne National Laboratory may help researchers and engineers overcome some of the hurdles that have inhibited the production of hydrogen for use in fuel cells.

Argonne chemist Michael Krumpelt and colleagues in Argonne's Chemical Engineering Division used "single-site" catalysts based on ceria or lanthanum chromite doped with either platinum or ruthenium to boost hydrogen production at lower temperatures during reforming. "We've made significant progress in bringing the rate of reaction to where applications require it to be," Krumpelt said.

Most hydrogen produced industrially is created through steam reforming. In this process, a nickel-based catalyst is used to react natural gas with steam to produce pure hydrogen and carbon dioxide.

These nickel catalysts typically consist of metal grains tens of thousands of atoms in diameter that speckle the surface of metal oxide substrates. On the other hand, the new catalysts that Krumpelt developed consist of single atomic sites imbedded in an oxide matrix. The difference is akin to that between a yard strewn with several large snowballs and one covered by a dusting of flakes. Because some reforming processes tend to clog much of the larger catalysts with carbon or sulfur byproducts, smaller catalysts process the fuel much more efficiently and can produce more hydrogen at lower temperatures......... Posted by: Sarah      Read more         Source