October 9, 2006, 9:05 PM CT

Hot Nanocrystals

Scientists at the Department of Energy's Lawrence Berkeley National Laboratory have discovered that nanocrystals of germanium embedded in silica glass don't melt until the temperature rises almost 200 degrees Kelvin above the melting temperature of germanium in bulk. What's even more surprising, these melted nanocrystals have to be cooled more than 200 K below the bulk melting point before they resolidify. Such a large and nearly symmetrical "hysteresis" - the divergence of melting and freezing temperatures above and below the bulk melting point - has never before been observed for embedded nanoparticles.

Phase transitions between solid and liquid or liquid and vapor are familiar phenomena in the everyday world, for example between solid water ice, liquid water, and water vapor, or steam. Eugene Haller of Berkeley Lab's Materials Sciences Division (MSD), who is also a professor of materials science at the University of California at Berkeley, uses an epicurean example: "When a solid piece of chocolate melts in the mouth, it releases a burst of flavors".

Haller explains that beyond broad scientific interest, the properties of germanium nanoparticles embedded in amorphous silicon dioxide matrices have promising applications. "Germanium nanocrystals in silica have the ability to accept charge and hold it stably for long periods, a property which can be used in improved computer memory systems. Moreover, germanium dioxide (germania) mixed with silicon dioxide (silica) offers particular advantages for forming optical fibers for long-distance communication".........

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October 9, 2006, 8:49 PM CT

Genome Id Method Against Cancer

A mathematical discovery has extended the reach of a novel genome mapping method to humans, potentially giving cancer biology a faster and more cost-effective tool than traditional DNA sequencing.

A student-led group from the laboratory of Michael Waterman, USC University Professor in molecular and computational biology, has developed an algorithm to handle the massive amounts of data created by a restriction mapping technology known as "optical mapping." Restriction maps provide coordinates on chromosomes analogous to mile markers on freeways.

Lead author Anton Valouev, a recent graduate of Waterman's lab and now a postdoctoral fellow at Stanford University, said the algorithm makes it possible to optically map the human genome.

"It carries tremendous benefits for medical applications, specifically for finding genomic abnormalities," he said.

The algorithm appears in this week's PNAS Early Edition.

Optical mapping was developed at New York University in the late 1990s by David Schwartz, now a professor of chemistry and genetics at the University of Wisconsin-Madison. Schwartz and a collaborator at Wisconsin, Shiguo Zhou, co-authored the PNAS paper.

The power of optical mapping lies in its ability to reveal the size and large-scale structure of a genome. The method uses fluorescence microscopy to image individual DNA molecules that have been divided into orderly fragments by so-called restriction enzymes.........

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October 8, 2006, 6:43 PM CT

Detailed view of Victoria Crater

With stunningly powerful vision, the HiRISE camera on NASA's Mars Reconnaissance Orbiter has taken a remarkable picture that shows the exploration rover Opportunity poised on the rim of Victoria crater on Mars.

The High Resolution Imaging Science Experiment (HiRISE) camera detailed the entire 800-meter (roughly half-mile) Victoria crater and the rover -- down to its rover tracks and shadows -- in a single high-resolution image taken Wednesday (Oct. 3).

Alfred S. McEwen of the University of Arizona Lunar and Planetary Laboratory released portions of the image that show views of the rover and crater at a NASA press conference in Washington, D.C., today. McEwen is principal investigator for HiRISE, which is operated from UA's Lunar and Planetary Laboratory in Tucson.

"We're poised to have a fantastic mission, and we're not even at prime science mission yet," McEwen said at NASA press briefing this morning. "This was our very first attempt to image 'off-nadir' (at an angle as opposed to straight down), and it worked fabulously well," McEwen added. "It's been an exciting week".

The HiRISE images for Victoria crater are available online at http://hiroc.lpl.arizona.edu/images/TRA/TRA_000873_1780/........

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October 8, 2006, 6:37 PM CT

Whiskers Sense Three-dimensional World

A number of mammals use their whiskers to explore their environment and to construct a three-dimensional image of their world. Rodents, for example, use their whiskers to determine the size, shape and texture of objects, and seals use their whiskers to track the fluid wakes of their prey.

Two Northwestern University engineers have been studying the whisker system of rats to better understand how mechanical information from the whiskers gets transmitted to the brain and to develop artificial whisker arrays for engineering applications.

Mitra J. Hartmann, assistant professor of biomedical engineering and mechanical engineering in the McCormick School of Engineering and Applied Science, and Joseph H. Solomon, one of Hartmann's graduate students, have now developed arrays of robotic whiskers that sense in two dimensions, mimicking the capabilities of mammalian whiskers. They demonstrate that the arrays can sense information about both object shape and fluid flow.

A paper about the arrays, which may find application on assembly lines, in pipelines or on land-based autonomous rovers or underwater vehicles, was reported in the Oct. 5 issue of the journal Nature.

"We show that the bending moment, or torque, at the whisker base can be used to generate three-dimensional spatial representations of the environment," said Hartmann. "We used this principle to make arrays of robotic whiskers that in a number of respects closely replicate rat whiskers." The technology, she said, could be used to extract the three-dimensional features of almost any solid object.........

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October 8, 2006, 5:57 PM CT

Devoting More Research To Webicillin

Could a dose of webicillin beat that stubborn infection? Could a cobweb bandage help soldiers and accident victims with bleeding wounds? Is a wrapping of spider silk the key to preventing the body from rejecting implants?

A review of research on spider silk concludes that researchers have largely overlooked such possible medical applications of this extraordinary natural material, which is stronger than steel. In a report in the current (Sept. 13) issue of the ACS monthly journal Chemical Reviews, Randolph V. Lewis, of the University of Wyoming, describes other scientific research on spider silk during the last 15 years.

"Very few studies of biological testing of spider silk have been done in a rigorous manner," Lewis states. "There is a large body of folklore concerning the antibiotic, wound-healing, and clot-inducing activity of spider silk. However, much of that lore has not been seriously tested." The lore dates to the first century A.D. when spider webs were prized as wound dressings. They even found a place in Shakespeare's Midsummer Night's Dream: "I shall desire you of more acquaintance, good master cobweb," the character "Bottom" said. "If I cut my finger, I shall make bold of you".

The scanty scientific evidence is tantalizing, Lewis notes. He cites, for instance, animal studies concluding that spider silks do not induce an immune response -- which causes rejection of implants.........

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October 6, 2006, 5:05 AM CT

Tongue scrapers only slightly reduce bad breath

Bad breath is a common problem for many people, given the wide variety of substances traveling through our mouths daily. Some people avoid offensive foods and drinks, chew gum, use mouth rinses, or eat mints to mask unpleasant odor. Others cannot escape bad breath quite so easily. At least 40 million Americans suffer from halitosis. Unfortunately, there is no standard treatment for it.

According to a study in the September/recent issue of General Dentistry, the Academy of General Dentistry's (AGD) clinical, peer-reviewed journal, halitosis is a term used to describe any disagreeable odor of expired air. Bad breath is a generally accepted term for foul smells emanating from the mouth. Oral malodor is a term reserved for unpleasant smells originating from the oral cavity. "A common reason for bad breath is post-nasal drip, which coats the back area of the tongue with bacteria-rich mucous," says AGD spokesperson, June Lee, DDS, MAGD. "A tongue scraper is often effective in relieving oral malodor caused by sinus drainage".

The study reviewed literature examining the effects of using tongue scrapers to brush the tongue, rather than using a toothbrush to scrape the tongue. Data revealed that a tongue cleaner/scraper demonstrated a significant difference in reducing volatile sulfur compounds (VSC) levels, which are produced when bacteria and amino acids interact to produce bad breath.........

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October 6, 2006, 4:54 AM CT

Black Hole Musical: Epic But Off-Key

A gigantic sonic boom generated by a supermassive black hole has been found with NASA's Chandra X-ray Observatory, along with evidence for a cacophony of deep sound.

This discovery was made by using data from the longest X-ray observation ever of M87, a nearby giant elliptical galaxy. M87 is centrally located in the Virgo cluster of galaxies and is known to harbor one of the Universe's most massive black holes.

Researchers detected loops and rings in the hot, X-ray emitting gas that permeates the cluster and surrounds the galaxy. These loops provide evidence for periodic eruptions that occurred near the supermassive black hole, and that generate changes in pressure, or pressure waves, in the cluster gas that manifested themselves as sound.

"We can tell that a number of deep and different sounds have been rumbling through this cluster for most of the lifetime of the Universe," said William Forman of the Harvard-Smithsonian Center for Astrophysics (CfA).

The outbursts in M87, which happen every few million years, prevent the huge reservoir of gas in the cluster from cooling and forming a number of new stars. Without these outbursts and resultant heating, M87 would not be the elliptical galaxy it is today.

"If this black hole wasn't making all of this noise, M87 could have been a completely different type of galaxy," said team member Paul Nulsen, also of the CfA, "possibly a huge spiral galaxy about 30 times brighter than the Milky Way".........

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October 5, 2006, 10:10 PM CT

Clinical Applications For New DESI Technology

Purdue University researchers have created the first two-dimensional images of biological samples using a new mass spectrometry technique that furthers the technology's potential applications for the detection of diseases such as cancer.

The technology, desorption electrospray ionization, or DESI, measures characteristic chemical markers that distinguish diseased from non-diseased regions of tissue samples within a few seconds and has eliminated the need for samples to be treated with chemicals and specially contained.

This tool has a wide range of applications and could be used in the future to address many medical issues, said Graham Cooks, Purdue's Henry B. Hass Distinguished Professor of Analytical Chemistry in whose lab DESI was developed.

"This technology could be used to aid surgeons in precisely and completely removing cancerous tissue," he said. "With these images, we can see the exact location of tumor masses and can detect cancerous sites that are indistinguishable to the naked eye".

Current surgical methods rely on the trained eye of a pathologist who views stained tissue slices under a microscope to assess what tissue must be removed.

This study was the first to take the graphical data presented by DESI mass spectrometry and turn it into a two-dimensional image of the tissue, said Demian Ifa, a member of Cooks' research team.........

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October 5, 2006, 9:55 PM CT

Plenty Of Carbon Dioxide Storage Capacity

As concern has grown over the effects of the human release of carbon dioxide (CO2) gas into the atmosphere, so too has research into technologies to manage CO2. One such research project, overseen by geologist Brandon Nuttall at the Kentucky Geological Survey (KGS) at the University of Kentucky, has investigated the option for geologic sequestration of captured CO2 in Devonian black shales, organic-rich rocks found beneath about two thirds of Kentucky.

Geologic sequestration refers to the process of permanent underground storage of carbon dioxide captured from sources such as coal-fired power plants, cement plants, and others manufacturing plants. Widespread deposits of shale are generally believed to be the seal or cap for deeper storage reservoirs that would prevent sequestered CO2 from leaking to the surface. Injection of CO2 into black gas-producing shales may have an additional value of enhancing the recovery of natural gas.

In the three year project funded by National Energy Technology Laboratory of the U.S. Department of Energy, Nuttall determined that the deeper and thicker parts of the Devonian shales in Kentucky could provide a potentially large geologic storage reservoir for captured CO2. In fact, the extensive occurrence of shales in geologic basins across North America would make them an attractive regional reservoir for economic CO2 sequestration.........

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October 4, 2006, 8:22 PM CT

Light On Evolution Of Life Cycles

In the history of life on earth, one intriguing mystery is how plants made the transition from water to land and then went on to diversify into the array of vegetation we see today, from simple mosses and liverworts to towering redwoods.

A research team led by University of Michigan evolutionary biologist Yin-Long Qiu has new findings that help resolve long-debated questions about the origin and evolution of land plants. The work will be published online this week in the Proceedings of the National Academy of Sciences.

Two major steps kicked off the chain of events that helped land plants prosper, forming the basis for modern land-based ecosystems and fundamentally altering the course of evolution of life on earth, said Qiu. The first step was the colonization of land by descendents of aquatic plants known as charophyte algae. That event opened up a vast new world where the sun's intensity was undiminished by passage through water and where carbon dioxide-another essential ingredient for plant life-was abundant.

The second event was a key change in plant life cycles. Plants exhibit a phenomenon known as alternation of generations, in which two alternating forms with different amounts of DNA make up a complete life cycle. One form, known as a sporophyte, produces spores, which grow into individuals of the other form, called gametophytes. Gametophytes produce gametes-eggs and sperm-which unite to form a fertilized egg capable of becoming a new sporophyte, thus completing a life cycle. While all plants exhibit alternation of generations, some spend most of their life cycle as sporophytes, and others spend more time in the gametophyte phase.........

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