May 2, 2006, 0:21 AM CT

First Neutrons Produced

One of the largest and most anticipated U.S. science construction projects of the past several decades has passed its most significant performance test. The Department of Energy's Spallation Neutron Source, located at Oak Ridge National Laboratory, has generated its first neutrons.

Research conducted at the SNS will lay the groundwork for the next generation of materials research. Researchers think that the greatly improved ability to understand the structure of materials could lead to a virtually limitless number of innovations, including stronger and lighter airplanes, a new generation of batteries and fuel cells, and time-released drugs that target a specific body organ.

Just after 2 p.m. Friday, a pulse of protons from the SNS's accelerator complex, traveling at nearly the speed of light, struck its mercury target. The protons "spalled" neutrons from the nuclei of mercury circulating inside the target. These first neutrons were recorded on equipment specially installed for the commissioning.

"To have observed 'first neutrons' on the initial SNS run is a tribute to the men and women who have worked so hard to design, construct, and now operate this magnificent facility," said Dr. Raymond L. Orbach, Director of the DOE Office of Science. "To bring a project of this scale and cost to completion on budget and ahead of schedule represents a model for all future large scale scientific projects to emulate. All of us owe all who have contributed to this achievement sincere thanks and appreciation for the opportunities you have now created for our world. It is a great moment for science."........

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April 29, 2006, 1:42 PM CT

Do Constants Of The Universe Change

Physicists at JILA have performed the first-ever precision measurements using ultracold molecules, in work that may help solve a long-standing scientific mystery--whether so-called constants of nature have changed since the dawn of the universe.

The research, published in the April 14 issue of Physical Review Letters,* involved measuring two phenomena simultaneously--electron motion, and rotating and vibrating nuclei--in highly reactive molecules containing one oxygen atom and one hydrogen atom. The scientists greatly improved the precision of these microwave frequency measurements by using electric fields to slow down the molecules, providing more time for interaction and analysis. JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

Compared to the prior record, set more than 30 years ago, the JILA team improved the precision of one frequency measurement 25-fold and another 10-fold. This was achieved by producing pulses of cold molecules at various speeds, hitting each group with a microwave pulse of a selected frequency, and then measuring how a number of molecules were in particular energy states. The apparatus and approach were similar to those used in the NIST-F1 cesium atomic fountain clock, the nation's primary time standard, raising the possibility of designing a clock that keeps time with molecules, instead of atoms.........

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April 26, 2006, 7:56 PM CT

Chemist Discovers Secret Behind Nature's Medicines

After years of wondering how organisms managed to create self-medications, such as anti-fungal agents, chemists have discovered the simple secret.

Researchers already knew that a particular enzyme was able to coax a reaction out of stubborn chemical concoctions to generate a large family of medically valuable compounds called halogenated natural products. The question was, how do they do it?.

Chemists would love to have that enzyme's capability so they could efficiently reproduce, or slightly re-engineer, those products, which include antibiotics, anti-tumor agents, and fungicides.

Thanks to MIT chemistry Associate Professor Catherine L. Drennan's recent crystallography sleuthing, the secret to the enzyme's enviable prowess has come to light and it appears almost anti-climactic. It's simply a matter of the size of one of its parts.

"If an enzyme is a gun that fires to cause a reaction, then we wanted to know the mechanism that pulls the trigger," Drennan said. "In chemistry, we often have to look at 'molecules in, molecules out.' With halogenated natural products, though, we couldn't figure out how it happened, because the chemicals are so nonreactive. Now that we have the enzyme's structure and figured out how it works, it makes sense. But it's not what we would have predicted."........

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April 24, 2006, 7:13 PM CT

New materials for high efficiency organic solid state lighting

A new organic molecule developed by PNNL researchers may significantly improve the efficiency of organic solid state lighting. Direct conversion of electricity to light in "solid state" thin films of organic molecules occurs in organic light emitting devices which can be far more efficient than conventional "incandescent" light bulbs.

In an OLED, light emitting molecules harvest positive and negative charge carriers from oppositely charged electrodes to create excitons, which collapse to give light emission. By using organometallic phosphors, a photon can be emitted for every electron used so there is no wasted current.

But until now, no good host materials were available to transport the charge to blue phosphorescent light emitters. And, without an efficient blue component, it is not possible to generate the high quality white light mandatory for indoor lighting. The PNNL team is solving this problem by linking small organic molecules together using inorganic "phosphine oxide" connecting units to make larger molecules that transport charge but do not interfere with the blue light emission process.........

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April 24, 2006, 7:10 PM CT

Nanoporous 'sponge' Removes Mercury From Offshore

Contaminated water resulting from offshore oil and gas platform drilling contains mercury and other toxic heavy metals. Mercury concentrations in these retrieved waters can be as high 2,000 parts per billion, therefore they need to be treated before they can be safely discharged to the environment. The complex mixture of constituents including salts and petroleum hydrocarbons presents a challenge for mercury removal using currently available conventional technologies.

Scientists at PNNL have developed a novel nanoporous sorbent thiol-SAMMS, or thiol-functionalized Self Assembled Monolayers on Mesoporous Supports, to specifically remove mercury and other contaminants such as cadmium and lead from produced waters and condensate liquids from natural gas. Working with a filtration equipment company in Texas, PNNL recently demonstrated that thiol-SAMMS was effective in removing more than 99 percent of mercury from gas condensate liquids containing approximately 800 ppb mercury. The thiol-SAMMS technology is a recipient of a R&D 100 award and recently received the 2006 Federal Laboratory Consortium award for successful technology transfer for commercial use. Steward Advanced Materials in Chattanooga, Tenn., is now licensed to commercially produce thiol-SAMMS.........

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April 24, 2006, 6:45 AM CT

Next Generation Fuel Cells

The pressure to develop cleaner, more efficient single sources of heat and electrical energy is the driving force behind the development of solid oxide fuel cells (SOFCs) at NRC and elsewhere. However, if SOFCs are to become commercially viable, production costs must be lower and the reliability, as well as durability of these systems needs improvement.

NRC Institute for Chemical Process and Environmental Technology (NRC-ICPET) researchers, Drs. Pamela Whitfield, Gisele Amow and Isobel Davidson, teamed up with Dr. Stephen Skinner (Department of Materials, Imperial College, U.K.) to collaborate on a project that tackled these challenges.

The research was funded by the NRC-British Council Joint S&T Fund and involved comparing methods to synthesize novel cathode materials using a conventional Pechini process and a non-conventional production method - microwave-assisted synthesis. The novel cathode materials produced by both methods were then evaluated for their potential use in intermediate temperature SOFCs.

The two teams worked together on developing new cathode compositions in a family of oxides known to be hyperstoichiometric in oxygen. In this class of materials the ionic transport of oxygen is augmented by interstitial oxide ions within the structure's crystal lattice. Led by Dr. Skinner, the British team provided expertise on measuring oxide ion mobility using a technique of isotopic exchange and secondary ion mass spectroscopy. The research led to new cathode compositions with greater ionic conductivity, thereby decreasing the amount of energy necessary for oxygen ion mobility and enabling the fuel cell to operate at lower temperatures. Lower operating temperatures can increase the durability of SOFCs and makes smaller-scale applications, such as portable power units, more feasible.........

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April 20, 2006, 9:29 PM CT

Physicists Get To Heart Of Antimatter

Like Jekyll and Hyde, some subatomic particles are able to act as both matter and their antimatter counterparts. Known as mixing, this process has been known to quantum physicists for 50 years. Now it has been measured for the first time by an international collaboration involving MIT scientists.

The work could lead to a better understanding of the early universe, when these particles were present in great abundance.

The achievement was announced yesterday by Ivan Furic (MIT Ph.D. 2004), now at the University of Chicago, representing the Collider Detector at Fermilab (CDF) collaboration at the Fermi National Accelerator Laboratory.

The CDF team specifically reported rapid-fire transitions between matter and antimatter of a subatomic particle called the Bs (pronounced "B sub s") meson. They found that this particle oscillates between matter and antimatter states at a mind-boggling 3 trillion times per second.

The Bs itself is composed of other subatomic particles: a heavy "bottom quark" bound to a "strange anti-quark".

Christoph Paus, associate professor of physics (and Furic's thesis advisor at MIT), represents MIT in the CDF collaboration, a team of 700 physicists from 61 institutions and 13 countries. Paus, a member of MIT's Laboratory for Nuclear Science, led the data analysis effort involving 80 researchers from 27 institutions.........

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April 18, 2006, 10:44 PM CT

Unbreakable Quantum Encryption

Raw code for "unbreakable" encryption, based on the principles of quantum physics, has been generated at record speed over optical fiber at the Commerce Department's National Institute of Standards and Technology (NIST). The work, reported today at the SPIE Defense & Security Symposium in Orlando, Fla.,* is a step toward using conventional high-speed networks such as broadband Internet and local-area networks to transmit ultra-secure video for applications such as surveillance.

The NIST quantum key distribution (QKD) system uses single photons, the smallest particles of light, in different orientations to produce a continuous binary code, or "key," for encrypting information. The rules of quantum mechanics ensure that anyone intercepting the key is detected, thus providing highly secure key exchange. The laboratory system produced this "raw" key at a rate of more than 4 million bits per second (4 million bps) over 1 kilometer (km) of optical fiber, twice the speed of NIST's prior record, reported just last month.** The system also worked successfully, eventhough more slowly, over 4 km of fiber.

The record speed was achieved with an error rate of only 3.6 percent, considered very low. The next step will be to process the raw key, using NIST-developed methods for correcting errors and increasing privacy, to generate "secret" key at about half the original speed, or about 2 million bps.........

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April 17, 2006, 9:30 PM CT

Crystal Sieves

The porous, sieve-like minerals known as zeolites have been used for decades in purifiers, filters and other devices. Yet creating and refining a new type of zeolite is still a matter of sophisticated trial and error: no one has been able to figure out exactly how the crystals form, even in the laboratory.

Now, however, a team of chemists, engineers and mathematicians, using some of the most advanced microscopes in the research arsenal, has uncovered new details for the step-by-step evolution from molecular soup to carefully engineered zeolite crystal.

With this knowledge, laboratories may be able to use targeted methods to create zeolites with precisely the crystal sizes and shapes demanded by molecule-specific applications such as chemical sensing.

University of Minnesota chemical engineer Michael Tsapatsis, graduate student and lead author Tracy Davis, and their colleagues report their findings Apr. 17, 2006, online in Nature Materials. The research was supported by several National Science Foundation (NSF) grants from across three Divisions.

Zeolites are familiar to consumers as, say, the white crystals in aquarium filters, or the ion-exchanging workhorses in advanced detergents. But their real economic impact is behind the scenes, where they are critical for extracting various chemical components out of petroleum and its byproducts on an industrial scale.........

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April 15, 2006, 3:48 PM CT

Graphite-based Circuitry May Be Foundation For New Devices

A study of how electrons behave in circuitry made from ultrathin layers of graphite - known as graphene - suggests the material could provide the foundation for a new generation of nanometer scale devices that manipulate electrons as waves - much like photonic systems control light waves.

In a paper published April 13 in Science Express, an online advance publication of the journal Science, researchers at the Georgia Institute of Technology and the Centre National de la Recherche Scientifique (CNRS) in France report measuring electron transport properties in graphene that are comparable those seen in carbon nanotubes. Unlike carbon nanotubes, however, graphene circuitry can be produced using established microelectronics techniques, allowing researchers to envision a "road map" for future high-volume production.

"We have shown that we can make the graphene material, that we can pattern it, and that its transport properties are very good," said Walt de Heer, a professor in Georgia Tech's School of Physics. "The material has high electron mobility, which means electrons can move through it without much scattering or resistance. It is also coherent, which means electrons move through the graphene much like light travels through waveguides".

The results should encourage further development of graphene-based electronics, though de Heer cautions that practical devices may be a decade away.........

Posted by: Sarah      Permalink         Source

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