July 9, 2008, 9:19 PM CT

Controlling the Size of Nanoclusters

Scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Stony Brook University have developed a new instrument that allows them to control the size of nanoclusters - groups of 10 to 100 atoms - with atomic precision. They created a model nanocatalyst of molybdenum sulfide, the first step in developing the next generation of materials to be used in hydrodesulfurization, a process that removes sulfur from natural gas and petroleum products to reduce pollution.

As published in the July 9, 2008 online edition of the Journal of Physical Chemistry C, the researchers made size-selected molybdenum sulfide nanoclusters as gaseous ions, and then gently deposited the clusters on a gold surface. The nanoclusters interact weakly with the gold support and therefore remain intact.

"With this new instrument, we can control how a number of and what type of atoms are in a nanocluster," said Brookhaven chemist Michael White, the principal author of the paper. "This knowledge enables us to make nanoclusters with predetermined size, structure and chemical composition, all which are important for the design of new catalysts."

Currently, molybdenum sulfide nanoparticles are used for hydrodesulfurization and other chemical processes, but it is not known what size is most active or how the reactions occur on small particles. The ability to make model nanocatalysts containing molybdenum sulfide particles of variable size and chemical makeup will allow White and coworkers to understand how current catalysts work and help design the next generation of catalysts......... Posted by: Kevin      Read more         Source

July 9, 2008, 9:11 PM CT

Flatfish fossils fill in evolutionary missing link

Hidden away in museums for more that 100 years, some recently rediscovered flatfish fossils have filled a puzzling gap in the story of evolution and answered a question that initially stumped even Charles Darwin.

All adult flatfishes--including the gastronomically familiar flounder, plaice, sole, turbot, and halibut--have asymmetrical skulls, with both eyes located on one side of the head. Because these fish lay on their sides at the ocean bottom, this arrangement enhances their vision, with both eyes constantly in play, peering up into the water.

This remarkable arrangement arises during the youth of every flatfish, where the symmetrical larva undergoes a metamorphosis to produce an asymmetrical juvenile. One eye 'migrates' up and over the top of the head before coming to rest in the adult position on the opposite side of the skull.

Opponents of evolution, however, insisted that this curious anatomy could not have evolved gradually through natural selection because there would be no apparent evolutionary advantage to a fish with a slightly asymmetrical skull but which retained eyes on opposite sides of the head. No fishfossil or livinghad ever been discovered with such an intermediate condition.

But in the 10 July 2008 issue of Nature, Matt Friedman, graduate student in the Committee on Evolutionary Biology at the University of Chicago and a member of the Department of Geology at the Field Museum, draws attention to several examples of such transitional forms that he uncovered in museum collections of underwater fossilized creatures from the Eocene epoch--about 50 million years ago......... Posted by: William      Read more         Source

July 8, 2008, 6:43 PM CT

How intense will storms get?

A new mathematical model indicates that dust devils, water spouts, tornadoes, hurricanes and cyclones are all born of the same mechanism and will intensify as climate change warms the Earth's surface.

The new equation, developed by University of Michigan atmospheric and planetary scientist Nilton Renno, could allow researchers to more accurately calculate the maximum expected intensity of a spiraling storm based on the depth of the troposphere and the temperature and humidity of the air in the storm's path. The troposphere is the lowest layer of Earth's atmosphere.

This equation improves upon current methods, Renno says, because it takes into account the energy feeding the storm system and the full measure of friction slowing it down. Current thermodynamic models make assumptions about these variables, rather than include actual quantities.

"This model allows us to relate changes in storms' intensity to environmental conditions," Renno said. "It shows us that climate change could lead to increases in how efficient convective vortices are and how much energy they transform into wind. Fueled by warmer and moister air, there will be stronger and deeper storms in the future that reach higher into the atmosphere".

Renno and research scientist Natalia Andronova used the model to quantify how intense they expect storms to get based on current climate predictions. For every 3.6 degrees Fahrenheit that the Earth's surface temperature warms, the intensity of storms could increase by at least a few percent, the researchers say. For an intense storm, that could translate into a 10 percent increase in destructive power......... Posted by: Tyler      Read more         Source

July 3, 2008, 9:23 PM CT

Radicals Shake Up Molecules

Until now, it was usually thought that colliding molecules get the shakes as the result of energy transfer solely from the smashing of the molecules, but some new research adds a second means by which colliding molecules become vibrationally excited--it is being called the "Tug o' War Mechanism".

The new experiment, transforming the textbook story, waccording toformed in the lab of Richard Zare, chair of the Department of Chemistry at Stanford University. This work on energy transferring, or inelastic, collisions is featured in the July 3, 2008 issue of the journal Nature.

"How energy transfer occurs in molecular collisions is a topic of deep interest to chemists, for energy transfer is often the precursor to chemical transformations," Zare said. "This is the reason why I regard finding a new mechanism for energizing molecules through collisions to be of such potential importance".

"The work by Zare and colleagues shows an interesting and unexpected result," shared Charles Pibel, director of the Physical Chemistry Program at the National Science Foundation (NSF). "The conventional wisdom had been that most collisions between molecules excite vibrational motion through a hard impact, like a piano's hammer striking a string."

But instead of molecules impacting and deflecting backwards, the Tug o' War Mechanism stretches the molecule and then releases it, starting the molecule rattling. The effect is "more like a violinist, plucking a string, pizzicato." In the collisions studied by the Zare group, a lone hydrogen atom tugs on one end of a deuterium molecule and lets go, exciting the molecular deuterium into vibration......... Posted by: Sarah      Read more         Source

July 3, 2008, 9:18 PM CT

Species Have Come and Gone

View a video interview with researcher John Alroy of the National Center for Ecological Analysis and Synthesis.

Diversity among the ancestors of such marine creatures as clams, sand dollars and lobsters showed only a modest rise beginning 144 million years ago with no clear trend afterwards, according to an international team of researchers. This contradicts previous work showing dramatic increases beginning 248 million years ago and may shed light on future diversity.

"Some of the time periods in the past are analogies for what is happening today from global warming," says Jocelyn Sessa of Penn State. "Understanding what happened with diversity in the past can help us provide some prediction on how modern organisms will fare. If we know where we have been, we know something about where it will go".

Using contemporary statistical methods and a paleobiology database, the researchers report in the July 4 issue of Science, a new diversity curve that shows that most of the early spread of invertebrates took place well before the Late Cretaceous, and that the net increase through the period since, is proportionately small relative to the 65 million years that elapsed. The research team was led by John Alroy of the University of California at Santa Barbara......... Posted by: William      Read more         Source

July 3, 2008, 9:00 PM CT

Extended cyclone relief efforts aided from space

Earth observation satellites have provided vital information to relief workers in Myanmar throughout a especially long crisis response window following the devastating Cyclone Nargis that hit the country on 2 and 3 May 2008.

Immediately after the disaster, the UN Office for the Coordination of Humanitarian Affairs (OCHA) asked the International Charter on 'Space and Major Disasters', referred to as 'the Charter', for support by providing immediate crisis mapping of the affected areas.

Following the request, rapid mapping products were created with Earth observation (EO) satellite acquisitions taken in the wake of the event to derive an estimation of the flood surge impact and other damage information to help plan emergency response operations.

Damage maps were able to be created quickly because the RESPOND project, which delivers satellite mapping for disaster reduction and humanitarian aid, had delivered EO-derived topographic maps of Myanmar a month before the disaster.

This activity was part of a project to help local communities reduce exposure to disaster risks. This enabled the RESPOND team to compare up-to-date basic maps before the disaster with satellite images acquired during or after the cyclone impact.

Thanks to the Charter more than 10 different sensors - radar and optical - from several EO missions provided more than 60 satellite images, which were used to derive 29 damage maps......... Posted by: Tyler      Read more         Source

July 1, 2008, 9:58 PM CT

Best treatment for MS may depend on disease subtype

ANN ARBOR, Mich. Animal studies by University of Michigan researchers suggest that people who experience the same clinical signs of multiple sclerosis (MS) may have different forms of the disease that require different kinds of therapy.

The results, if borne out in further studies, point to a time when doctors will be able to target specific inflammatory processes in the body and more effectively help MS patients, using available drugs and new ones in the pipeline.

Since the 1990s, the therapy picture has brightened for people with multiple sclerosis in its most common form, relapsing-remitting MS. Beta interferon drugs and glatiramer acetate (marketed as Copaxone) have proved effective at decreasing the attack rate and suppressing inflammatory plaque development in a number of patients with MS. Yet why the drugs help some patients, but not others, has remained a mystery.

The U-M research team conducted the studies in mice that have a disease similar to MS: experimental autoimmune encephalomyelitis or EAE. The team observed that different inflammatory chemicals, whose activity is associated with two different types of immune system T cells, could bring on the same paralysis and other MS-like signs. They also showed that drugs that block one of the inflammation pathways were not effective at blocking the other. The results, published online ahead of print, will appear in the July 7 issue of the Journal of Experimental Medicine........ Posted by: Sean      Read more         Source

June 30, 2008, 6:48 PM CT

Physicists create millimeter-sized 'Bohr atom'

HOUSTON -- June 30, 2008 -- Nearly a century after Danish physicist Niels Bohr offered his planet-like model of the hydrogen atom, a Rice University-led team of physicists has created giant, millimeter-sized atoms that resemble it more closely than any other experimental realization yet achieved.

The research is available online in Physical Review Letters

Bohr offered the first successful theoretical model of the atom in 1913, suggesting that electrons traveled in orbits around the atom's nucleus like planets orbiting a star. Bohr's model led to a deeper understanding of both the chemical and optical properties of atoms and won him a Nobel Prize in 1922. But his notion of electrons traveling in discrete orbits was eventually displaced by quantum mechanics, which revealed that electrons don't have precise positions but are instead distributed in wave-like patterns.

"In a sufficiently large system, the quantum effects at the atomic scale can transition into the classical mechanics found in Bohr's model," said lead researcher Barry Dunning, Rice's Sam and Helen Worden Professor of Physics and Astronomy. "Using highly excited Rydberg atoms and a series of pulsed electric fields, we were able to manipulate the electron motion and create circular, planet-like states"......... Posted by: Sarah      Read more         Source

June 26, 2008, 8:50 PM CT

New Nano Technique Significantly Boosts Boiling Efficiency

Whoever penned the old adage "a watched pot never boils" surely never tried to heat up water in a pot lined with copper nanorods.

A new study from scientists at Rensselaer Polytechnic Institute shows that by adding an invisible layer of the nanomaterials to the bottom of a metal vessel, an order of magnitude less energy is mandatory to bring water to boil. This increase in efficiency could have a big impact on cooling computer chips, improving heat transfer systems, and reducing costs for industrial boiling applications.

"Like so a number of other nanotechnology and nanomaterials breakthroughs, our discovery was completely unexpected," said Nikhil A. Koratkar, associate professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer, who led the project. "The increased boiling efficiency seems to be the result of an interesting interplay between the nanoscale and microscale surfaces of the treated metal. The potential applications for this discovery are vast and exciting, and we're eager to continue our investigations into this phenomenon."

Bringing water to a boil, and the related phase change that transforms the liquid into vapor, requires an interface between the water and air. In the example of a pot of water, two such interfaces exist: at the top where the water meets air, and at the bottom where the water meets tiny pockets of air trapped in the microscale texture and imperfections on the surface of the pot. Even though most of the water inside of the pot has reached 100 degrees Celsius and is at boiling temperature, it cannot boil because it is surrounded by other water molecules and there is no interface - i.e., no air - present to facilitate a phase change......... Posted by: Kevin      Read more         Source

June 26, 2008, 8:43 PM CT

Quantum computing breakthrough

The odd behavior of a molecule in an experimental silicon computer chip has led to a discovery that opens the door to quantum computing in semiconductors.

In a Nature Physics journal paper currently online, the scientists describe how they have created a new, hybrid molecule in which its quantum state can be intentionally manipulated - a mandatory step in the building of quantum computers.

"Up to now large-scale quantum computing has been a dream," says Gerhard Klimeck, professor of electrical and computer engineering at Purdue University and associate director for technology for the national Network for Computational Nanotechnology.

"This development may not bring us a quantum computer 10 years faster, but our dreams about these machines are now more realistic".

The workings of traditional computers haven't changed since they were room-sized behemoths 50 years ago; they still use bits of information, 1s and 0s, to store and process information. Quantum computers would harness the strange behaviors found in quantum physics to create computers that would carry information using quantum bits, or qubits. Computers would be able to process exponentially more information.

If a traditional computer were given the task of looking up a person's phone number in a telephone book, it would look at each name in order until it found the right number. Computers can do this much faster than people, but it is still a sequential task. A quantum computer, however, could look at all of the names in the telephone book simultaneously......... Posted by: Kevin      Read more         Source