April 15, 2006, 2:08 PM CT

Testing Fluid Compatibility

Good news for industries that uses mixing of various fluids. Mixing of these fluids have a tendency to bead up and pull away from each other.

To help industrial engineers improve their ability to systematically test new product formulations, scientists at the National Institute of Standards and Technology (NIST) have developed a microfluidic instrument that quickly measures interfacial tension.

The instrument is relatively simple and includes a series of channels ranging from 700 micrometers to 50 micrometers wide. Fluids are pumped toward a "T" intersection where drops of one liquid are pinched off and flow along a "river" of the second liquid. As the spherical drops flow through constriction points in the channel, they speed up and elongate. The degree to which the drops stretch out depends on the interfacial tension between the two fluids. High levels of tension exert more pressure on the drops, keeping them more nearly spherical.

Just as the mood of a party goes through stages, the tension between newly mixed liquids can change over time, and the device tracks these changes as the drops move downstream through the channel. A camera captures 100 pictures per second to record the changes, and an algorithm analyzes the data and produces a measurement in approximately 1 second.........

Posted by: Sarah      Permalink         Source

April 14, 2006, 9:47 AM CT

Interstellar Chemical Tamed in The Lab

Chemists at the University of California, Riverside have created in the laboratory a type of molecule thought to exist only in interstellar space, which may have valuable applications in the chemical industry.

The finding of their paper, titled Cyclopropenylidenes: From Interstellar Space to an Isolated Derivative in the Laboratory are being released recently in Science Express a precursor to its publication in the journal Science. The co-authors are Vincent Lavallo, Yves Canac and Bruno Donnadieu who work in the laboratory of Distinguished Professor of Chemistry Guy Bertrand at UCR; and Chemistry Professor Wolfgang W. Schoeller of Gera number of's Universität Bielefeld.

"This is about a compound that is very abundant in deep space, which was supposed to not be able to exist in the laboratory, and we found a way to slightly modify it and make it stable," said Bertrand.

The new molecule belongs to a family of compounds known as carbenes, very few of which are stable. However, carbenes are now widely used to prepare catalysts that have a number of applications in industries such as pharmaceuticals, plastics and other petrochemicals. The cyclopropenylidene that exists naturally in space is made of three carbon atoms arranged in a triangle with two hydrogen atoms attached. The UCR scientists synthesized a more stable version by replacing the hydrogen with two nitrogen atoms. Because of its unique shape and size, the new carbene prepared at UCR might lead to even more powerful catalysts.........

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April 12, 2006, 11:53 PM CT

Frictionless Motion In Water

By using ultra-short laser pulses to spin a cyanide molecule like a propeller, chemists at the University of Southern California and Brown University have achieved the first known demonstration of near-frictionless motion in water. Eventhough the discovery has no immediate practical use, says USC chemist Stephen Bradforth, "it impacts how we think about the vast majority of chemical reactions"--90 percent of which take place in liquid solutions.

Indeed, the technique gives chemists a potential new tool to influence how a reaction progresses, as one way to do that is to isolate an interacting molecule from its surroundings.

In experiments they describe in a recent issue of the journal Science, the chemists start with a water sample containing cyanide ions, each of which is basically a molecular stick with a carbon atom at one end and a nitrogen atom at the other. Then they spin the sticks to with a laser.

Within the first quarter-turn, each rotating cyanide ion creates a shock wave that throws back the surrounding water molecules. (Bradforth, who is part of the study team, likens the phenomenon to a passenger swinging a suitcase in a crowded airport terminal, minus the real-life bruises and hurt feelings.) Inside the resulting bubble, the molecule will then continue whirling for a time with essentially no friction.........

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April 6, 2006, 11:00 PM CT

5-Million-Year Climate Record

Using chemical clues mined from ocean mud, Brown University scientists have generated the longest continuous record of ocean temperatures on Earth.

The 5-million-year record is a history of temperatures in the eastern equatorial Pacific, or EEP, located off the coast of South America. The area is an anomaly - a huge swath of cool water in the tropics - that plays an important role in global climate. In the EEP, trade winds pull nutrient-rich cold water to the surface, which makes for fertile fisheries off the coasts of Peru, Chile and Ecuador. The interplay of wind and water can also fuel El Niño events, a large-scale warming in the EEP that slows the upwelling of cold water and forces changes in weather, such as droughts or floods, far from the tropical Pacific.

In the EEP, the Brown geology team found that surface temperatures were 27 degree C 5 million years ago. Surface temperatures are 23 degree C today. In between, they found a pattern of steady cooling - roughly one degree Celsius every million years.

This finding, published in Science, contradicts the long-standing notion that rapid glacier growth in the high northern latitudes about 3 million years ago alone set off dramatic cooling of the global climate. The finding shows instead that glaciation was part of a long-term cooling trend.........

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April 5, 2006, 11:06 PM CT

New 'wrinkle' In Botox Treatment

There may soon be a better way to fight unsightly wrinkles. Scientists have discovered a novel way to increase the potency of botulinum neurotoxin therapys - usually known as Botox - that they say could one day allow patients to receive the injections less frequently while maintaining or even enhancing its cosmetic benefits.

By allowing lower doses, the new approach could also make the therapy safer by reducing the risk of complications associated with immune system recognition that can sometimes occur with frequent injections, as per researchers at the Scripps Research Institute in La Jolla, Calif. Smaller, more potent doses may even lead to lower prices for the popular wrinkle-remover, the scientists say. Their study is reported in the March 29 issue of the weekly Journal of the American Chemical Society.

Eventhough popular for removing wrinkles, Botox is also used to treat a growing number of other conditions, including migraine headaches, lazy eyes and excessive sweating. It is developed from the botulinum neurotoxin, the most lethal poison known and a potential bioterrorist weapon. In a medical setting, small doses of a purified version of the toxin block the release of a chemical (acetylcholine) that signals muscle contraction, resulting in a localized, temporary paralysis that erases wrinkles and unwanted muscle spasms.........

Posted by: Sarah      Permalink         Source

April 4, 2006, 10:49 PM CT

Add Two Atoms and Lots of Heat

Dump baking soda into a glass of vinegar and a chemical reaction occurs. Molecules start a chaotic dance, bouncing and bumping into each other. Friction, which primes molecules for the dance then cools them off when it is done, is the result.

Richard Stratt pictures the process this way: "It's like pushing through a crowded airport terminal. Everyone is jostling each other. And you just can't seem to get to your gate. That's the kind of motion - and friction - at play in chemical reactions".

But Stratt, a Brown University professor of chemistry, and his colleagues at the University of Southern California have hit upon a surprise. They found an example of molecular motion in a chemical reaction that actually destroys friction. This superfast molecule, which makes a whopping 270 trillion rotations per minute, literally pushes away molecules that surround it in solvent, wiping out most of the resulting frictional force.

"We found a case where this molecule is spinning so fast that it manipulates the arrangement of molecules around it in just the right way to annihilate friction," Stratt said. "To go back to the airport analogy, we found the obnoxious guy who muscles his way through the crowd and makes his plane".

Results of the experiments, reported in the current issue of Science, add a new wrinkle to old beliefs about molecular motion and energy transfer during chemical reactions.........

Posted by: Sarah      Permalink         Source

April 4, 2006, 0:14 AM CT

Confirming Neutrino Oscillation

By sending a high-intensity beam of subatomic particles known as neutrinos from a laboratory in Batavia, Ill., to a particle detector located deep in a mine in Soudan, Minn., scientists have confirmed the neutrinos really do "oscillate," changing from one kind to another as they fly along.

The payoff could be a deeper understanding of the ghostly neutrino particles, which can traverse the entire Earth without interacting with matter. Ultimately, in fact, these elusive particles may help us understand the origins of the neutrons, protons and electrons that make up all the matter in the world around us.

Such oscillations have been observed in earlier experiments. But new experiments from the Main Injector Neutrino Oscillation Search (MINOS) based at the Fermi National Accelerator Laboratory will eventually examine the effect in much greater detail, and under controlled conditions.

"Using a man-made beam of neutrinos, MINOS is a great tool to study the properties of neutrinos in a laboratory-controlled environment," said Stanford University professor Stan Wojcicki, spokesperson for the experiment.

Their first result corroborates earlier observations of muon neutrino disappearance, made by the Japanese Super-Kamiokande and K2K experiments.

"Over the next few years, we will collect about 15 times more data, yielding more results with higher precision, paving the way to better understanding this phenomenon," Wojcicki said.........

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April 3, 2006, 11:41 PM CT

Solitary Vibrations In Uranium

Los Alamos scientists, working with collaborators from around the world, recently observed experimental evidence of solitary vibrations (solitons) in a solid. First observed as localized waves on the surface of water more than a century ago, the concept of solitons in solids was only theorized as possible two decades ago. The results of their discovery of random localized vibrations in a 3-D solid will add new knowledge to the field of solid-state physics and could have implications for other areas of science and technology.

In research described in this week's issue of Physical Review Letters, Los Alamos scientist Michael Manley and colleagues from Oak Ridge and Argonne national laboratories and the Institute for Transuranium Elements in Karlsruhe, Gera number of describe their use of x-ray and neutron scattering experiments to identify random localized vibrations, called lattice solitons, in uranium crystals at high temperatures, possibly caused by strong electron-phonon interactions.

As per Manley, "these results are really exciting on several levels. Eventhough the idea of a localized energy wave goes back to the late 1800s when solitons were first observed, by the 1980s new theories proposed the possibility of seeing them in discrete solids. Researchers have been looking for localized vibrations in atomic structures ever since. No one ever imagined that they would play such an important role in the physical properties of uranium metal, so this was quite a surprise".........

Posted by: Sarah      Permalink         Source

March 30, 2006, 4:29 PM CT

Intense Heat From Gold Nanoparticles

Nanoparticles of gold can act as tiny, precise and powerful heaters, which potentially could be used in biomedical applications, as per a new study.

When stimulated with the right frequency of laser light, a small collection of metal nanoparticles, such as gold, can heat an area up to 1,000 times its size, as per Ohio University researchers Hugh Richardson and Sasha Govorov.

The heating properties were observed in ice, water and a polymer shell that was designed to mimic material in biological systems. Though the ice did not melt when heated by low-intensity laser alone, it dissolved once a gold nanoparticle was embedded, said the scientists, whose findings have been published online by the journal Nano Letters.

The gold particle is 50 nanometers, which is 200,000 times smaller than an object 1 centimeter in size, Govorov said.

The process not only generates a considerable amount of heat at much larger scale than the nanoparticle, but also is very precise, the scientists report. By using bio-linkers, the nanoparticles can be designed to affect specific targets. Bio-linkers are special, sticky molecules that are created to link with only certain types of cells. In a biomedical application, a few gold nanoparticles could be used to generate heat to impact a single macro-scale object, such as a tumor cell.........

Posted by: Kevin      Permalink         Source

March 29, 2006, 10:56 PM CT

Tiny water purification packet may save lives

Chemists have developed a powerful household water purification system that puts the cleansing power of an industrial water treatment plant into a container the size of a ketchup packet. The researchers have shown that the tiny packet, which acts as a chemical filter, can be added to highly contaminated water to dramatically reduce pathogen-induced diarrhea - the top killer of children in much of the developing world.

The packets also show promise for boosting water safety during emergencies and natural disasters, such as earthquakes, floods and hurricanes, where water purity is suddenly compromised, the researchers say. The lifesaving packets, whose use is being expanded globally, was described today at the 231st national meeting of the American Chemical Society.

Worldwide, approximately 1.5 million children under age five die each year from simple diarrhea acquired from pathogens found in drinking water, according to public health experts. That translates to about 4,000 children dying each day as a result of contaminated water.

"It's like a 9-11 catastrophe happening everyday worldwide, but this is a tragedy that can be prevented," says Greg Allgood, Ph.D., director of Procter & Gamble's Children's Safe Drinking Water program, which manufactures the packets. The company has been developing the packets since 1995 in collaboration with the U.S. Centers for Disease Control and Prevention (CDC).........

Posted by: Sarah      Permalink         Source

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