October 4, 2006, 8:16 PM CT

Carbon Nanotubes To Detect Defects In Composites

Two University of Delaware researchers have discovered a means to detect and identify damage within advanced composite materials by using a network of tiny carbon nanotubes, which act in much the same manner as human nerves.

The discovery has important implications both in the laboratory, where the scientists hope to better predict the life span of various composite materials, and in everyday applications, where it could become an important tool in monitoring the health of composite materials used in the construction of a variety of essential products, including commercial airliners.

The research is the work of Tsu-Wei Chou, Pierre S. du Pont Chair of Engineering, and Erik Thostenson, assistant professor of mechanical engineering, and is featured in an article in the Oct. 2 issue of the influential journal Advanced Materials.

Chou said the research team has been working in the field of fiber composites in conjunction with UD's Center for Composite Materials and of late has taken an interest in the reinforcement of composites with minute nanomaterials--a nanometer is a bare one billionth of one meter--and particularly with carbon nanotubes.

"Carbon nanotubes are very small but have superb qualities," Chou said. "They are very light, with a density about one-half that of aluminum, which itself is considered exceptionally light in comparison to other metals, and yet are 30 times as strong as high-strength steel and as stiff as diamonds".........

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October 4, 2006, 4:36 AM CT

Morganella Pyriformis

Morganella pyriformis is a puffball. The mature fruiting body of the fungus bursts open and releases the spores, after some physical force has been applied. I've been known to help a few of these along.

Prior to 2003, this fungus was known as Lycoperdon pyriforme. It has since been moved out of the genus Lycoperdon based on molecular evidence and morphological difference to other members of the genus. No longer is the evocative common name suggested by Tom Volk a literal translation of the genus name. A different common name, pear-shaped puffball, is perhaps more proper. After all, the epithet pyriformis does mean "in the form of Pyrus (pear)". However, I'll personally use the one proposed by Tom, because I know I'll never forget it.

Tom's article also has a story about the results of deeply inhaling the spores of puffballs (don't do it). Illustrations and descriptions of Morganella pyriformis are available from both Mykoweb and Michael Kuo's MushroomExpert.com.........

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October 3, 2006, 10:15 PM CT

Ultrafast Photochemical Reactions

MIT researchers have made a fundamental advance in understanding how different environments affect chemical reactions by devising a novel way to observe ultrafast photochemical reactions--reactions induced by a pulse of laser light--in crystals.

The new MIT experiments show that the reaction dynamics, including whether the product molecules remain or recombine to reform the original compound, depend with exquisite sensitivity on the local "cage" environment formed by neighboring molecules in the crystal. Cage effects of this sort play crucial roles in many natural and industrial chemical processes.

The method they have developed allows them to observe other light-induced changes in solids, including those used to burn CDs and DVDs. For some materials, these transitions may be reversible, allowing information to be both written and erased.

"This is a very active area of research for both fundamental and practical reasons," said Keith Nelson, MIT professor of chemistry and leader of the team. "What we're able to see, in a simple and direct way, is how different local environments around the reacting species lead to extremely different dynamics and different outcomes".

The work was published in the Aug. 31 online issue of Science. Nelson's co-author on the paper is Peter Poulin, a former graduate student in his lab.........

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October 3, 2006, 10:11 PM CT

Nanoparticles To Aid Brain Imaging

If you want to see precisely what the 10 billion neurons in a person's brain are doing, a good way to start is to track calcium as it flows into neurons when they fire.

To that end, Alan Jasanoff at the McGovern Institute for Brain Research at MIT has developed a new nano-sized calcium-sensing contrast agent that is detectable by magnetic resonance imaging (MRI) scanners, machines that can be used for detailed noninvasive brain imaging.

The work is reported in the early online edition of the Proceedings of the National Academy of Sciences the week of Sept. 25-29.

In an application known as functional MRI (fMRI), MRI machines are already increasingly used to observe brain functions as people--or animals--undertake various activities like reading or learning. But Jasanoff notes that current fMRI technology has limitations.

"Using conventional fMRI to study the brain is like trying to understand how a computer works by feeling which parts of it are hot because of energy dissipation in different components," said Jasanoff, who also holds appointments as an assistant professor in MIT's Department of Nuclear Science and Engineering, Department of Brain and Cognitive Sciences, and Biological Engineering Division.

The analogy is apt, because fMRI indirectly measures neural activity by detecting changes in blood flow to brain regions with increased energy requirements. But these hemodynamic changes occur several seconds after the neurons actually fire, too slow to study precise neural activity. Further, the spacing of tiny blood vessels limits the spatial resolution of the technique to volumes containing at least 1,000 neurons, too coarse for discrimination of highly specialized functional areas within a brain region.........

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October 3, 2006, 9:50 PM CT

Myths about species abundance

A new report finds little empirical evidence to support a widely held ecological assumption that species are most abundant near the centers of their geographic ranges and decline in abundance near the ranges' edges.

"When we reviewed data from published studies that looked at species abundance at multiple sites across a range, we found almost no evidence that supported the so-called 'abundant-center hypothesis' and strong evidence that contradicted it," said Raphael D. Sagarin, associate director for oceans and coastal policy at Duke University's Nicholas Institute for Environmental Policy Solutions.

"This is troubling," Sagarin said, "because a lot of current thinking on ecological and evolutionary issues -- including how species will respond to climate change, how to identify probable locations of pest outbreaks, how genetic diversity is distributed among populations and where to locate habitat preserves -- has been based on the hypothesis".

The validity of these ideas now needs to be re-examined using empirical studies, he said.

Sagarin is one of the principal authors of the report, which appeared in the September 2006 issue of the journal Trends in Ecology and Evolution. Other authors are Steven D. Gaines of the University of California-Santa Barbara's Marine Science Institute and Department of Ecology, Evolution and Marine Biology; and Brian Gaylord of the University of California-Davis's Bodega Marine Laboratory and Section of Evolution and Ecology.........

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October 3, 2006, 5:17 AM CT

Chilly Bugs At Bottom Of The World

The larvae of Antarctic midges never stop producing special proteins that minimize environmental stress, allowing them to withstand a range of intense environmental conditions in one of the world's harshest environments.

Scientists found that adult midges (Belgica antarctica) lose their ability to continually express these protective heat-shock proteins. Instead, like most animals, adult midges produce these proteins only when they are stressed. The discovery currently appears in the online edition of the Proceedings of the National Academy of Sciences.

The proteins help defend the larval midges against environmental stresses including temperature changes as well as changes in water, oxygen and pH levels, said David Denlinger, the study's lead author and a professor of entomology at Ohio State University.

"They've somehow figured out a way to maintain a level of these heat-shock, or stress, proteins and still make proteins that are vital for growth and development," he said.

This mechanism seems to offer the larvae protection during their two-year life span, most of which is spent encased in ice.

All animals, including humans, make heat shock proteins, but normally they only do so during times of extreme physical stress. Curiously, adult midges don't express these proteins all the time - only during periods of extreme environmental stress. Yet when most insects express stress proteins, it temporarily compromises the production of other proteins, Denlinger said.........

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October 2, 2006, 10:10 PM CT

How did bilaterally symmetric flowers evolve?

How did bilaterally symmetric flowers evolve from radially symmetric ones? To address this important question, geneticists Francisco Perfectti and Juan Pedro M. Camacho, and ecologist Jos M. Gmez (Universidad de Granada, Spain) explored how different flower shapes affected plant fitness in natural populations of Erysimum mediohispanicum, a Mediterranean herb. Their findings would be reported in the recent issue of The American Naturalist.

The scientists observed that plants bearing bilaterally symmetrical flowers were more visited by pollinators and had higher fitness, measured by both the number of seeds produced per plant and the number of seeds surviving to the juvenile stage, than plants with radially symmetric flowers.

"This study reveals that natural selection can play a key role in the evolution of flower bilateral symmetry," says Camacho. "Our data also suggest that it is possible to understand the evolution of complex forms by means of microevolutionary analyses, as complementary tools to those coming from developmental genetics".........

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October 2, 2006, 9:29 PM CT

A Magnetic-Semiconductor Sandwich

Researchers at Ohio University have created an improved magnetic semiconductor that solves a problem spintronics scientists have been investigating for years.

Unlike classic or vintage electronics that operate on electronic charges, spin-based electronics focuses on the spin of electrons to carry and store information. Researchers predict spintronics will revolutionize the electronics industry by making devices faster, improving storage capacity and reducing the amount of power needed to run them.

Spintronics technology has not been widely applied yet, however, because scientists have had difficulty controlling, manipulating and measuring the electrons.

In a paper published online today in Physical Review Letters, a team of Ohio University and Ohio State University scientists led by postdoctoral fellow Erdong Lu have created an effective interface between a semiconductor and ferromagnetic metal. The two-layer "sandwich" of gallium nitride (GaN) and manganese gallium (MnGa) nearly eliminates any intermixing of the two layers and allows the spin to be "tuned".

"We found a way to grow the metal on the semiconductor. The crystalline match between the two materials was nearly perfect. The advantage of this finding is in the growth process. By adjusting the conditions of the growth, we can tune the spin," said Arthur Smith, associate professor of physics and astronomy and director of Ohio University's Nanoscale & Quantum Phenomena Institute.........

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October 1, 2006, 8:28 PM CT

Hearts Or Tails?

A new paper in the recent issue of G&D elucidates the genetics of heart formation in the sea squirt, and lends surprising new insight into the genetic changes that may have driven the evolution of the multi-chambered vertebrate heart.

Brad Davidson and colleagues in Michael Levine's lab at UC Berkeley have discovered that the transcription factor Ets1/2, along with the signaling molecule FGF, controls early heart formation in the sea squirt, Ciona intestinalis.

Sea squirts are most commonly found in shallow ocean waters attached to algae, rocks or seaweed. They have been used for over 100 years as a highly useful experimental model organism for the study of animal development. A simple chordate, Ciona is being used in the lab to study the heart development of higher organisms because it shares several characteristics with vertebrates - although ultimately, Ciona, develops a heart with just one chamber (as opposed to vertebrates' multi-chambered heart).

All of the cells that form the Ciona heart are originally derived from two early embryonic cells (called bastomeres). These cells divide into separate lineages: the smaller rostral cells become heart muscle, while the larger caudal cells become tail muscle. Davidson and colleagues found that Ets1/2 underlies the cells' decision to become either heart or tail. When activated, Ets1/2 instructs cells to form heart muscle.........

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October 1, 2006, 8:15 PM CT

What Drives Your Taste Buds

What are the genes that are crucial to the taste bud development?

The gene, SOX2, stimulates stem cells on the surface of the embryonic tongue and in the back of the mouth to transform into taste buds, as per the researchers. Stem cells are immature cells that can develop into several different cell types depending on what biochemical instructions they receive.

"Not only did we find that SOX2 is crucial for the development of taste buds, but we showed that the amount of SOX2 is just as important," said Brigid Hogan, Ph.D., chair of the Duke University Medical Center Department of Cell Biology and senior member of the research team. "If there isn't enough SOX2 present, or if there is too much, the stem cells will not turn into taste buds".

The scientists made their discovery in mice, but they believe the same process occurs in humans.

As per the researchers, the findings will help researchers better understand how the behavior of certain stem cells is controlled. The SOX2 gene is already known to be crucial in controlling whether embryonic stem cells remain undifferentiated and whether stem cells in the brain, eye and inner ear differentiate into specialized nerve cells.

Taste bud cells, much like skin cells, continually slough off and are replaced by new ones. So the new findings not only provide insights into the interactions between SOX2 and tongue stem cells during embryonic development, but also into how stem cells continue to operate in adults, the scientists said.........

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