September 20, 2006, 5:13 AM CT
Ceramic microreactors for on-site hydrogen production
Researchers at the University of Illinois at Urbana-Champaign have designed and built ceramic microreactors for the on-site reforming of hydrocarbon fuels, such as propane, into hydrogen for use in fuel cells and other portable power sources.
Applications include power supplies for small appliances and laptop computers, and on-site rechargers for battery packs used by the military.
"The catalytic reforming of hydrocarbon fuels offers a nice solution to supplying hydrogen to fuel cells while avoiding safety and storage issues correlation to gaseous hydrogen," said Paul Kenis, a professor of chemical and biomolecular engineering at Illinois and corresponding author of a paper accepted for publication in the journal Lab on a Chip, and posted on its Web site.
In prior work, Kenis and his colleagues developed an integrated catalyst structure and placed it inside a stainless steel housing, where it successfully stripped hydrogen from ammonia at temperatures up to 500 degrees Celsius.
In their latest work, the scientists incorporated the catalyst structure within a ceramic housing, which enabled the steam reforming of propane at operating temperatures up to 1,000 degrees Celsius. Using the new ceramic housing, the scientists also demonstrated the successful decomposition of ammonia at temperatures up to 1,000 degrees Celsius.........
Posted by: Sarah Permalink Source
September 18, 2006, 9:37 PM CT
Metal deformation studies
By combining very large-scale molecular dynamics simulations with time-resolved data from laser experiments of shock wave propagation through specific metals, scientists at the Lawrence Livermore National Laboratory are now able to better understand the evolution of high-strain-rate plasticity.
Plastic deformation of metals results from the motion of a high density of dislocation lines. A strong shock produces an unusual number of dislocations within a metal's crystalline lattice, which changes the metal's mechanical properties such as strength, ductility and resistance to fracture and cracking.
In a paper published in the Sept. 17 edition of the journal Nature Materials, Livermore researchers, in conjunction with scientists from the University of Oxford, have compared and validated strong shock molecular dynamics simulations to dynamic experimental data in metals.
"We calculated the time needed for the metal to generate defects and relax in a strong shock wave," said Eduardo Bringa, LLNL's lead author of the paper. "We came to understand this time interval in terms of the time needed for line defects (dislocations) to move far enough to relax the strain. It was known that the more dislocations that are produced and the more they move, the more the strain is relaxed".........
Posted by: Sarah Permalink Source
September 17, 2006, 10:18 PM CT
Supporting Industrial Zeolites
The National Institute of Standards and Technology (NIST) has issued three new reference materials to support scientists studying the properties of commercially important zeolites.
First described in the 18th century, zeolites have seen increasing use in industry and commerce from cat litter to industrial catalysts and "molecular sieves." Zeolites belong to class of materials called alumino-silicates whose crystal structures form highly porous, nanoscale "cages" that can filter and trap small molecules. Naturally occurring zeolites are mined and widely used as absorbents in products such as cat litter. Tailored synthetic zeolites have a wide variety of more specialized applications, such as in laundry detergents (where they replace pollution-causing phosphates), and as catalysts in oil refineries. Because they can be designed with pores that pass only molecules of a certain size and shape, zeolites have excited considerable interest as molecular sieves for chemical separations--they are used in oxygen generation systems for medical oxygen, for example.
It is often extremely difficult to make precision measurements of key chemical characteristics for zeolites because they are ferociously hygroscopic. Humidity must be precisely controlled--and specified--to make meaningful measurements of the elemental content, for example. This has made it difficult to compare experimental results between different labs.........
Posted by: Sarah Permalink Source
September 5, 2006, 9:13 PM CT
Life Beyond Carbon
Photo / Donna Coveney
John Heywoo
If all nations burned gasoline for transportation at the same rate as the United States, world gasoline consumption would rise nearly ten-fold, with a corresponding hike in the concentration of greenhouse gases.
That's just one reason why it is imperative that nations work to create a more sustainable transportation system, says John Heywood, director of MIT's Sloan Automotive Lab and the Sun Jae Professor of Mechanical Engineering.
"As the countries in the developing world rapidly motorize, the increasing global demand for fuel will pose one of the biggest challenges to controlling the concentration of greenhouse gases in the atmosphere," Heywood writes in "Fueling Our Transportation Future," an article he wrote for the recent issue of Scientific American.
Heywood is one of three MIT professors who tackle energy in the magazine's September issue, whose cover proclaims the theme "Energy's Future: Beyond Carbon".
While Heywood's article focuses on improving transportation efficiency, MIT Professors John Deutch and Ernest Moniz explore the possibilities of expanding nuclear power to reduce emissions of greenhouse gases.
All three professors are members of MIT's Energy Research Council, which issued a report in May exploring how MIT can help solve the global energy crisis.........
Posted by: Sarah Permalink Source
September 5, 2006, 7:39 PM CT
Industry Impact of Chemical Controls
The National Institute of Standards and Technology (NIST) has co-organized with U.S. industry a workshop to address the increasing pressure on manufacturers from emerging chemical controls and regulations from such countries as China and the European Union. The suite of issues stemming from regulatory actions in various markets, as well as global reporting and management efforts, has serious cost and market implications both for manufacturers of chemicals and for chemicals users and are potential barriers to innovation.
The workshop, "Innovation and Competitiveness: A Strategic Approach to Emerging Chemical Issues," will be held on Sept. 26-27 at the NIST laboratories in Gaithersburg, Md.
The costs of dealing with multiple chemical regulation and control requirements in different markets goes far beyond the chemical industry itself. Chemicals and chemical products contribute 16 percent of the value of material inputs in the automotive sector, 33 percent of the value of material inputs used to make semiconductors, and 30 percent of the value of medical supplies, for example. The European Union's "End-of-Life-Vehicles" (ELV) Directive affected thousands of U.S. automotive suppliers. A study conducted by the Original Equipment Suppliers Association (OESA) observed that the average cost for inputting data into the International Material Data System (IMDS), a tool for complying with the ELV requirements, was $75 per simple raw material and up to $2,500 per complex assembly. In 2002, an Automotive Industry Action Group (AIAG) project team used these data and estimated that total costs to the entire U.S. supply chain for ELV compliance would be in the hundreds of millions of dollars.........
Posted by: Sarah Permalink Source
September 5, 2006, 7:20 PM CT
Gold Nanoparticles Are Hot Stuff
Gold nanoparticles are highly efficient and sensitive "handles" for biological molecules being manipulated and tracked by lasers, but they also can heat up fast-by tens of degrees in just a few nanoseconds-which could either damage the molecules or help study them, as per researchers at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and University of Colorado at Boulder.
Biophysicists often study nanoscale and even picoscale mechanics by using lasers to both apply force to and track the position of fragile biomolecules such as DNA or protein by manipulating a tiny sphere-typically polystyrene-attached to the molecule. The JILA team would like to find new microsphere materials that can be trapped by laser radiation pressure more efficiently, which would enable faster measurements and detection of smaller motions at the same laser power. As described in the Aug. 15 issue of Optics Letters,* the JILA team demonstrated that 100-nanometer-wide gold beads, as expected because of their metallic nature, can be trapped and detected six times more easily than polystyrene particles of a similar size.
However, the researchers also observed that gold absorbs light and heats up quickly, by a remarkable 266 degrees (Celsius) per watt of laser power, at the wavelength most often used in optical traps. Unless very low laser power is used, the heat could damage the molecules under study. Thus, gold beads would not be useful for temperature-sensitive experiments or applying force to molecules. But the heating effect could be useful in raising local temperatures in certain experiments, such as heating a protein just enough to allow researchers to watch it unfold, the paper suggests.........
Posted by: Sarah Permalink Source
September 5, 2006, 6:50 PM CT
Secrets of the Atomic Switch
Researchers at the Commerce Department's National Institute of Standards and Technology (NIST) have used a beam of electrons to move a single atom in a small molecule back and forth between two positions on a crystal surface, a significant step toward learning how to build an "atomic switch" that turns electrical signals on and off in nanoscale devices.
The results, described in the Aug. 18, 2006, issue of Science,* are the first would be published about work at NIST's new Center for Nanoscale Science and Technology (www.nist.gov/public_affairs/releases/cnst.htm).
"It's still futuristic to talk about a real atomic switch but we're getting closer," says physicist Joseph Stroscio, lead author of the paper. In addition, by applying the findings to nanoscale fabrication on semiconductors and insulating thin films, it may be possible to develop new classes of electronic and magnetic devices constructed atom by atom.
In the work described in Science, NIST physicists used a custom-built, cryogenic scanning tunneling microscope (STM)-which provides a voltage and beam of electrons at its needle-like tip-to perform several different types of atomic scale measurements and manipulations. NIST theorists performed calculations of the atoms' electronic structure, which confirmed the experimental results.........
Posted by: Sarah Permalink Source
September 4, 2006, 10:01 PM CT
Insights Into Lead Pollution
Valuable evidence about the success of the lead petrol ban has been gathered from otters by a scientist at Cardiff University.
As well as providing important new information about the secretive otter species, post-mortems on otters killed by cars since 1992 gave an insight into the levels of lead pollution in the environment. The results have important implications for human health as lead can damage the central nervous system including the brain, as well as affecting the kidney and reducing growth, especially in children.
Researcher Dr Liz Chadwick in the School of Biosciences at the University said:
"We measured the level of lead in rib-bones taken from over 300 otters found dead in south-west England between 1992 and 2004 and collected by wildlife veterinary pathologist Vic Simpson.
"We compared this with levels of lead found in stream sediment by the British Geological Society and airborne emissions recorded by the National Atmospheric Emissions Inventory. While some variation correlation to geology, we found an extremely strong decline over time, reflecting declining emissions from car fuel: otter bone lead levels in 2004 were less than a quarter of those in 1992."
Dr Chadwick stresses that the research highlights the importance of long-term monitoring and archiving of samples and shows that with help from the public, valuable use can be made of undesirable events such as wildlife road traffic accidents.........
Posted by: Sarah Permalink Source
August 31, 2006, 5:37 AM CT
A better water test
Water is essential for life. Nevertheless, even small amounts of water in the wrong places such as fuels, lubricants, or organic solvents can cause motors to sputter, metal parts to rust, or chemical reactions to go awry. That's why one of the most common lab tests performed in industry is one that looks for traces of water in other substances, even though the test itself is complicated and time-consuming.
A new method for detection and measurement of small amounts of water, developed in the lab of Dr. Milko van der Boom in the Weizmann Institute's Organic Chemistry Department, might allow such tests to be performed accurately and quickly. Van der Boom and postdoctoral fellow Dr. Tarkeshwar Gupta created a versatile film on glass that is only 1.7 nanometers thick. The film can measure the number of water molecules in a substance even when it contains only a few parts per million.
"The problem," says van der Boom, "is that water is hard to detect and to quantify." His method is a departure from prior sensing techniques. In general, such sensor systems are based on relatively weak but selective "host-guest" interactions. In the Weizmann Institute team's sensor, metal complexes embedded in the film steal electrons from the water molecules. When the number of electrons in the metal complexes changes, so does their color, and this change can be read optically. Devices based on optical readout do not need to be wired directly to larger-scale electronics an issue that's still a tremendous challenge for much of molecular-based electronics.........
Posted by: Sarah Permalink Source
August 31, 2006, 5:29 AM CT
honoring African American chemist Percy Julian
Pioneering chemist Percy Julian subject of upcoming NOVA documentary.
The American Chemical Society is hosting a symposium honoring pioneering African American chemist Percy Julian, Ph.D., at its 232nd National Meeting in San Francisco on Sept. 11. The symposium is part of the celebration of Julian, whose life story is the subject of a two-hour PBS/NOVA documentary scheduled to be broadcast on Feb. 6, 2007, during Black History month.
One of the sessions at the symposium -- "Dr. Percy L. Julian Scientist, Humanist, Educator, Entrepreneur, and Inspirational Trailblazer" -- will offer a sneak preview of the documentary, which is entitled, "Forgotten Genius," written and produced by Llewellyn Smith, writer/producer/director of Vital Pictures, Inc.; Steve Lyons, writer/producer of Moreno, Lyons Productions LLC; and Melanie Wallace, senior series producer, NOVA/WGBH.
"Forgotten Genius" is, as per Smith, "a first time portrait of this remarkable American chemist The NOVA documentary brings to the public the forgotten achievements of this 20th century scientist." The film is part of NOVA's Lives in Science series.
Percy Lavon Julian was born in Montgomery, Ala., on April 11, 1899. The son of a railway clerk and the grandson of slaves, his early schooling was spotty in the segregated South of the early 20th century. Even so, he was accepted as a freshman at DePauw University in Greencastle, Ind., at the age of 17; he graduated first in his class in 1920. He then taught for two years at Fisk University before enrolling in a Master's program at Harvard.........
Posted by: Sarah Permalink Source
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