November 21, 2006, 8:38 PM CT

Ultra-Intense Laser Blast Creates True 'Black Metal'

"Black gold" is not just an expression anymore. Researchers at the University of Rochester have created a way to change the properties of almost any metal to render it, literally, black.

The process, using an incredibly intense burst of laser light, holds the promise of making everything from fuel cells to a space telescope's detectors more efficient-not to mention turning your car into the blackest black around.

"We've been surprised by the number of possible applications for this," says Chunlei Guo, assistant professor of optics at the University of Rochester. "We wanted to see what would happen to a metal's properties under different laser conditions and we stumbled on this way to completely alter the reflective properties of metals".

The key to creating black metal is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second. To get a grasp of that kind of speed-a femtosecond is to a second what a second is to about 32 million years.

During its brief burst, Guo's laser unleashes as much power as the entire grid of North America onto a spot the size of a needle point. That intense blast forces the surface of the metal to form and nanostructures-pits, globules, and strands that both dramatically increase the area of the surface and capture radiation. Some larger structures also form in subsequent blasts.........

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November 21, 2006, 8:32 PM CT

The Smell Of Money

It's not hard to recall the pungent scent of a handful of pocket change. Similar smells emanate from a sweat-covered dumbbell or the water emerging from an old metal pipe. Yet no one has been able to identify the exact chemical cause of these familiar odors.

Now, scientists supported by a National Science Foundation (NSF) MUSES award and the UFZ Environmental Research Center in Gera number of have shown that these odor molecules come not from the penny or the pipes, but from metal-free chemicals erupting into the air when organic substances like sweat interact with the metallic objects.

The researchers--Andrea Dietrich, Dietmar Glindemann, Hans-Joachim Staerk and Peter Kuschk, all from Virginia Tech in Blacksburg--published their findings in the Oct. 20, 2006, Angewandte Chemie International Edition.

"We are the first to demonstrate that when humans describe the 'metallic' odor of iron metal, there are no iron atoms in the odors," said Dietrich. "The odors humans perceive as metallic are really a body odor produced by metals reacting with skin".

Because the makeup of byproduct molecules depends on which organic substances are reacting, the scientists believe the findings could help identify problem odors in potable water or aid doctors searching for disease markers in sweat or other body fluids.........

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November 19, 2006, 9:26 PM CT

Insights Into Periodic Table

The periodic table of chemical elements hangs in front of chemistry classrooms and in science laboratories worldwide. Yet much was unknown about its history and evolution until now.

"The moment I discovered there was this elegant, orderly chart that encompassed chemistry, I fell in love with the periodic table," said Eric Scerri, a UCLA chemist and author of the recently published "The Periodic Table: Its Story and Its Significance" (Oxford University Press). "It captured my imagination, and it still does. It is completely unique in science. Chemistry is the only field with one simple chart that embodies the essence of the field. This wonderful tool serves to organize the whole of chemistry".

Who discovered the periodic table of elements --the fundamental materials of which all matter is composed? There is no simple answer. The story begins with the ancient Greek philosophers. Aristotle, among others, identified four elements: earth, water, fire and air. Some elements -- such as iron, copper, gold and other metals -- have been known since antiquity.

Today, the periodic table has 116 elements, the most recent of which was added just last month -- an element that for now is known as element 118 for the number of protons in its nucleus, more than in any other element. (Two other elements are predicted from the existence of spaces in the periodic table, but have still not been synthesized.).........

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November 16, 2006, 9:25 PM CT

Edible Food Wrap Kills Deadly E. Coli

Researchers have improved upon an edible coating for fresh fruits and vegetables by enabling it to kill deadly E. coli bacteria while also providing a flavor-boost to food. Composed of apple puree and oregano oil, which acts as a natural antibacterial agent, the coating shows promise in laboratory studies of becoming a long-lasting, potent alternative to conventional produce washes, according to a team of scientists from the U.S. Department of Agriculture (USDA) and the University of Lleida in Spain.

The study comes on the heels of the recent deadly E. coli outbreak in spinach and amid growing concern by experts that some produce-cleaning techniques may not be effective in destroying E. coli. The study is scheduled for the Nov. 29 issue of the American Chemical Society's Journal of Agricultural and Food Chemistry.

"All produce-cleaning methods help to some degree, but our new coatings and films may provide a more concentrated, longer-lasting method for killing bacteria," says Research Leader Tara H. McHugh, Ph.D., a food chemist with the USDA's Agricultural Research Service in Albany, Calif. As the films are made of fruit or vegetable puree, they also provide added health benefits such as vitamins, minerals and antioxidants, she says.

Researchers have known about the antimicrobial activity of plant-derived essential oils for some time, but McHugh says that her group is the first to incorporate them into a fruit- or vegetable-based edible food wrap for the purpose of improving food safety. Three years ago, she and her associates developed a similar edible food wrap, but without the antimicrobial properties.........

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November 16, 2006, 8:27 PM CT

Exotic Relatives Of Protons And Neutrons

A team of scientists, including four at The Johns Hopkins University, has discovered two new subatomic particles, rare but important relatives of the familiar, commonplace proton and neutron.

Named "Sigma-sub-b" particles, the two exotic and incredibly quick to decompose particles are like rare jewels mined from mountains of data, said team leader Petar Maksimovic, assistant professor of physics and astronomy in the university's Krieger School of Arts and Sciences.

"These particles are members of what we call the 'baryonic' family, so-called for the Greek word 'barys,' which means heavy," Maksimovic said. "Baryons are particles that contain three quarks, which are the fundamental building blocks of matter".

The simplest baryons are the proton and neutron, which make up the nuclei of atoms of ordinary matter. "These newest members of that family are unstable and ephemeral, but they help us to understand the forces that bind quarks together into matter," Maksimovic said.

Containing the second-heaviest quark - called "the bottom quark" - the new particles are the heaviest baryons found yet: heavier even than a complete helium atom, which has two protons, though lighter than a lithium atom, which has three.

How rare is Sigma-sub-b? The team painstakingly analyzed a hundred trillion proton-antiproton collisions at the Tevatron, the world's most powerful particle accelerator, to find about 240 Sigma-sub-b candidates, Maksimovic said. The new particles are extremely short-lived, decaying within a tiny fraction of a second.........

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November 13, 2006, 9:02 PM CT

Phosphorus Another Culprit

Nitrogen is flowing down the Mississippi River and into the Gulf of Mexico faster than it can be consumed by floating microscopic plants called phytoplankton, increasing the size of the "dead zone" off the Louisiana coast. The findings, based on analysis of data gathered in 2001, are published online this week in the journal Environmental Science and Technology.

Because of the increased nitrogen levels, phytoplankton blooms are growing, and the Gulf's hypoxia zone -- an area lacking enough oxygen to sustain most life -- is getting bigger.

"In a pristine system, nutrients would flow down the river and into the Gulf, and there would be limited phytoplankton growth and no hypoxia," said James Ammerman, co-author of the paper and a biological oceanographer at Rutgers. "Heavy use of fertilizers containing nitrogen and phosphorus in the agriculture of the Mississippi Valley has thrown the system out of balance".

As per Ammerman, phytoplankton need both nitrogen and phosphorus to grow. Because they require a 16-to-1 ratio of nitrogen to phosphorus, phytoplankton commonly run out of nitrogen first; most coastal surface waters have ratios lower than 16-to-1.

"There is now so much nitrogen in the Gulf that even though phytoplankton consume it faster than they consume phosphorus, they can't get rid of it fast enough, and it's the phosphorus, instead of nitrogen, that runs out first and becomes the limiting nutrient," Ammerman said.........

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November 10, 2006, 4:29 AM CT

From Light To Sodium Atoms

For the first time, tornado-like rotational motions have been transferred from light to atoms in a controlled way at the National Institute of Standards and Technology (NIST). The new quantum physics technique can be used to manipulate Bose-Einstein condensates (BECs), a state of matter of worldwide research interest, and possibly used in quantum information systems, an emerging computing and communications technology of potentially great power.

As published in the Oct. 27 issue of Physical Review Letters,* the research team transferred orbital angular momentum--essentially the same motion as air molecules in a tornado or a planet revolving around a star--from laser light to sodium atoms.

The NIST experiment completes the scientific toolkit for complete control of the state of an atom, which now includes the internal, translational, and rotational behavior. The rotational motion of light previously has been used to rotate particles, but this new work marks the first time the motion has been transferred to atoms in discrete, measurable units, or quanta. Other researchers, as well as the NIST group, previously have transferred linear momentum and spin angular momentum (an internal magnetic state) from light to atoms.

The experiments were performed with more than a million sodium atoms confined in a magnetic trap. The atoms were chilled to near absolute zero and in identical quantum states, the condition known as a Bose-Einstein condensate in which they behave like a single "super-atom" with a jelly-like consistency. The BEC was illuminated from opposite sides by two laser beams, one of them with a rotating doughnut shape. Each atom absorbed one photon (the fundamental particle of light) from the doughnut laser beam and emitted one photon in the path of the other laser beam, picking up the difference in orbital angular momentum between the two photons. The interaction of the two opposing lasers created a corkscrew-like interference pattern, inducing the BEC to rotate--picture a rotating doughnut, or a vortex similar to a hurricane.........

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November 1, 2006, 4:04 AM CT

Recovering Pompeii

Artists in ancient Pompeii painted the town red 2,000 years ago with a brilliant crimson pigment that dominated a number of of the doomed city's wall paintings. Now researchers from France and Italy are reporting in the journal Analytical Chemistry why those paintings are undergoing a mysterious darkening. The synchrotron light of the European Synchrotron Radiation Facility (ESRF) in Grenoble (France) has provided new insight into this process and what produces it.

On 24 August of the year 79 AD, the volcano Vesuvius erupted burying its neighbouring towns in pumice and ash. The Villa Sora, in Torre del Greco, had since then remained inexistent, until twenty years ago, when excavation works brought it back to light. In the remains of the house, the distinctive red colour of the wall frescoes has turned black in a number of places since the excavation in a quick degradation process which is not well understood scientifically.

Researchers have been wondering for a number of years why the red in Pompeii walls, made of cinnabar (HgS), turns black. Already in the 1st century BC, Vitruvius, in his treatise "De Architectura", mentions the problem, which at that time, was prevented by applying a sort of protective varnish based on "punic wax". The causes and mechanisms responsible for cinnabar discolouration have remained a mystery until now; consequently conservators are unable to prevent the phenomenon from ocurring. The most usually acknowledged answer is that the exposure to the sun transforms cinnabar into another phase, metacinnabar, which is presented in a black colour. Recently a Franco-Italian team of scientists had studied four samples of wall paint from Villa Sora using the ESRF synchrotron light to verify whether this statement was correct.........

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October 31, 2006, 7:18 PM CT

Do I know you, sugar?

I was reading this interesting article today.

A molecule that can recognise carbohydrates could further the fight against infections.

The carbohydrate-containing compound lipid A is found in certain bacteria and can cause septic shock, a serious condition that may lead to organ failure and death. Ben Miller at the University of Rochester, New York, US, said molecules that selectively bind lipid A could be used to diagnose infection or to treat septic shock.

'Molecular recognition of carbohydrates is a challenging problem,' said Miller. 'Carbohydrates look a lot like bulk solvent, and are more complex than other biopolymers because they have a lot of branching points.' Despite these problems Miller and his University of Rochester co-workers succeeded in designing a molecule, called TW545, that recognises lipid A.

Miller describes TW545 as a 'stepping stone' towards new strategies for molecular recognition of carbohydrates. He is especially interested in using carbohydrate-binding molecules for diagnostic purposes. A number of proteins relevant to human health contain carbohydrate groups, said Miller, so molecules that recognise these could be put to good medical use.........

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October 29, 2006, 6:58 PM CT

Lighter And Cheaper Alloys

Car engines that consume less energy and can keep running on low oil, lead-free plumbing fixtures, and tanks that are light enough to be airlifted, but are just as rugged as the much heavier varieties.

They sound futuristic, but these products are already realities thanks to materials that stretch the limits of performance. Called cast metal matrix composites (MMCs), they are cheaper, lighter and stronger than their original alloys. In fact, an aluminum-based MMC developed at the University of Wisconsin-Milwaukee (UWM) can replace iron-based alloys.

"These composites have a number of applications in the transportation, small engines, aerospace and computer industries," says Pradeep Rohatgi, a Wisconsin Distinguished Professor of Engineering who pioneered cost-effective methods of manufacturing these composites.

Now more than a 100-million-a-year industry themselves, MMCs have been used in components for train brakes, thermal management devices in computers, and even the space shuttle and the Hubble Space Telescope.

MMCs are engineered by combining metal with a totally different class of material, such as ceramics and recycled waste. Incorporating the two materials the matrix and the reinforcement materials result in amazing structural and physical properties not available in the natural world.........

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