January 8, 2007, 9:15 PM CT

New Cancer Drugs

Combining synthetic chemistry techniques with a knowledge of the properties and actions of enzymes, scientists have been able to produce an exciting class of anti-cancer drugs originally isolated from blue-green algae.

This accomplishment is expected to make it possible to produce enough of the promising drugs for use in clinical trials.

In a study featured on the cover of the recent issue of the journal ACS Chemical Biology, a scientific team lead by University of Michigan Life Sciences Institute Research Professor David H. Sherman and researcher Zachary Q. Beck found the trick to turning the green gunk into gold-cancer fighting gold.

"It was simply too difficult to use the native blue-green algae for high-level production using traditional fermentation approaches," said Sherman. But the compound, called cryptophycin 1, held so much promise as an anti-cancer drug that organic chemists got busy trying to find ways to make a synthetic form of the compound in large enough quantities for clinical trials.

Developing an efficient synthetic route to natural product compounds and their analogs is often an essential step in drug development. With drugs such as penicillin and tetracycline, it can easily be done, but cryptophycins present more of a challenge. Sherman's team realized that with all cryptophycins, the most difficult step came very late in the synthesis, at the point at which a key part called an epoxide-a highly strained, three-membered ring oxygen-containing group, crucial for the drug's anti-cancer activity-becomes attached to the molecule.........

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January 7, 2007, 9:48 PM CT

Cheaper LEDs from Zinc Oxide

Engineers at UC San Diego have synthesized a long-sought semiconducting material that may pave the way for an inexpensive new kind of light emitting diode (LED) that could compete with today's widely used gallium nitride LEDs, as per a new paper in the journal Nano Letters.

To build an LED, you need both positively and negatively charged semiconducting materials. In an LED, when an electron meets a hole, it falls into a lower energy level and releases energy in the form of a photon of light. The UC San Diego engineers synthesized zinc oxide (ZnO) nanoscale cylinders that transport positive charges. The so-called "p-type ZnO nanowires" are endowed with a supply of positive charge carrying "holes" that, for years, have been the missing ingredients that prevented engineers from building LEDs from ZnO nanowires. In contrast, making "n-type" ZnO nanowires that carrier negative charge (electrons) has not been a problem. The starting materials and manufacturing costs for ZnO LEDs are far less expensive than those for gallium nitride LEDs.

Deli Wang, an electrical and computer engineering professor from UCSD's Jacobs School of Engineering, and his colleagues at UCSD and Peking University, report synthesis of high quality p-type zinc oxide nanowires in a paper published online by the journal Nano Letters.........

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January 7, 2007, 9:39 PM CT

Chemistry of Volcanic Fallout

A team of American and French researchers has developed a method to determine the influence of past volcanic eruptions on climate and the chemistry of the upper atmosphere, and significantly reduce uncertainty in models of future climate change.

In the January 5 issue of the journal Science, the scientists from the University of California, San Diego, the National Center for Scientific Research (CNRS) and the University of Grenoble in France report that the chemical fingerprint of fallout from past eruptions reveals how high the volcanic material reached, and what chemical reactions occurred while it was in the atmosphere. The work is especially relevant because the effect of atmospheric particles, or aerosols, is a large uncertainty in models of climate, as per Mark Thiemens, Dean of UCSD's Division of Physical Sciences and professor of chemistry and biochemistry.

"In predictions about global warming, the greatest amount of error is linked to atmospheric aerosols," explained Thiemens, in whose laboratory the method, which is based on the measurement of isotopes-or forms of sulfur-was developed. "Now for the first time, we can account for all of the chemistry involving sulfates, which removes uncertainties in how these particles are made and transported. That's a big deal with climate change".........

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January 7, 2007, 9:03 PM CT

An Enormous Halo Of Red Giant Stars

Astronomers have found an enormous halo of stars bound to the Andromeda galaxy and extending far beyond the swirling disk seen in images of the famous galaxy, our nearest large galactic neighbor. The discovery, reported at the American Astronomical Society meeting in Seattle, suggests that Andromeda is as much as five times larger than astronomers had previously thought.

"I am absolutely astounded by how big this halo is. As we looked farther and farther out, we kept finding stars that look like halo stars," said Puragra (Raja) Guhathakurta, professor of astronomy and astrophysics at the University of California, Santa Cruz, who will present the findings at the meeting.

Guhathakurta and his collaborators at UCSC, UCLA, and the University of Virginia are conducting an ongoing study of Andromeda's stellar halo, using observations at the Kitt Peak National Observatory in Arizona and the W. M. Keck Observatory in Hawaii. Their new findings are based on data gathered using the 4-meter Mayall Telescope at Kitt Peak and the DEIMOS spectrograph on the 10-meter Keck II Telescope in Hawaii.

The researchers detected a sparse population of red giant stars--bright, bloated stars in a late stage of stellar evolution--that appear to be smoothly distributed around the galaxy out to a distance of at least 500,000 light-years from the center. Even at that great distance, the stars are bound to the galaxy by gravity. These stars probably represent Andromeda's stellar halo, a distinct structural component of the galaxy that has eluded astronomers for over 20 years, Guhathakurta said.........

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January 7, 2007, 8:48 AM CT

A New Class Of Supernova

Evidence for a significant new class of supernova has been found with the European Space Agency's XMM-Newton and NASA's Chandra X-ray Observatory. These results strengthen the case for a population of stars that evolve rapidly and are destroyed by thermonuclear explosions. Such 'prompt' supernovas could be valuable tools for probing the early history of the cosmos.

A team of astronomers uncovered a puzzling situation when they examined X-ray data from DEM L238 and DEM L249, the remnants of two supernovas in a nearby galaxy. On the one hand, the unusually high concentration of iron atoms implied that the remnants are the products of thermonuclear explosions of white dwarf stars, a well-known type of supernova known as 'Type Ia'. On the other hand, the hot gas in the remnants was much denser and brighter in X-rays than typical Type Ia remnants.

(The large image shows a composite of Chandra X-ray data in blue and optical data in white of DEM L238 and DEM L249, two supernova remnants in the Large Magellanic Cloud. The inset reveals how DEM L238 (shown on the right in the wide-field view) appears in the three bands of X-ray emission, where low energy X-rays are shown in red, medium energies in green and high energies in blue. The central region of DEM L238 is green which indicates that it is rich in iron. This overabundance of iron identifies this object as a Type Ia supernova, possibly as a result from the explosion of a much younger star than expected.........

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December 28, 2006, 9:55 PM CT

Glow of Universe's First Objects

New observations from NASA's Spitzer Space Telescope strongly suggest that infrared light detected in a prior study originated from clumps of the very first objects of the universe. The recent data indicate this patchy light is splattered across the entire sky and comes from clusters of bright, monstrous objects more than 13 billion light-years away.

"We are pushing our telescopes to the limit and are tantalizingly close to getting a clear picture of the very first collections of objects," said Dr. Alexander Kashlinsky of NASA's Goddard Space Flight Center, Greenbelt, Md., lead author on two reports to appear in the Astrophysical Journal Letters. "Whatever these objects are, they are intrinsically incredibly bright and very different from anything in existence today".

Astronomers believe the objects are either the first stars -- humongous stars more than 1,000 times the mass of our sun -- or voracious black holes that are consuming gas and spilling out tons of energy. If the objects are stars, then the observed clusters might be the first mini-galaxies containing a mass of less than about one million suns. The Milky Way galaxy holds the equivalent of approximately 100 billion suns and was probably created when mini-galaxies like these merged.

This study is a thorough follow-up to an initial observation presented in Nature in November 2005 by Kashlinksy and his team. The new analysis covered five sky regions and involved hundreds of hours of observation time.........

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December 28, 2006, 9:37 PM CT

Carbon Dioxide Emissions Andt Atmosphere

Carbon dioxide emissions from the burning of fossil fuels will produce a 3 percent reduction in the density of Earth's outermost atmosphere by 2017, as per a team of researchers from the National Center for Atmospheric Research (NCAR) and Pennsylvania State University (PSU).

The research appears in the latest issue of the journal Geophysical Research Letters, and will be presented today at the American Geophysical Union conference in San Francisco, Calif.

"We're seeing climate change manifest itself in the upper as well as lower atmosphere," said NCAR scientist Stan Solomon, a co-author of the study. "This shows the far-ranging impacts of greenhouse gas emissions".

Lower density inthe thermosphere, which is the highest layer of the atmosphere, would reduce the drag on satellites in low Earth orbit, allowing them to stay airborne longer. Forecasts of upper-level air density could help NASA and other agencies plan the fuel needs and timing of satellite launches more precisely, potentially saving millions of dollars.

-----Confirming a prediction-----.

Recent observations by researchers tracking satellite orbits have shown that the thermosphere, which begins about 60 miles above Earth and extends up to 400 miles, is beginning to become less dense, said Robert Kerr, program director in the National Science Foundation's (NSF) Division of Atmospheric Sciences.........

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December 28, 2006, 8:54 PM CT

Insights Into Learning

Scientists analyzing the genomics of a marine snail have gotten an unprecedented look at brain mechanisms, discovering that the neural processes in even a simple sea creature are far from sluggish.

At any given time within just a single brain cell of sea slug known as Aplysia, more than 10,000 genes are active, according to scientists writing in Friday's (Dec. 29, 2006) edition of the journal Cell. The findings suggest that acts of learning or the progression of brain disorders do not take place in isolation - large clusters of genes within an untold amount of cells contribute to major neural events.

"For the first time we provide a genomic dissection of the memory-forming network," said Leonid Moroz, a professor of neuroscience and zoology at the University of Florida Whitney Laboratory for Marine Bioscience. "We took advantage of this powerful model of neurobiology and identified thousands of genes operating within a single neuron. Just during any simple event related to memory formation, we expect differences in gene expression for at least 200 to 400 genes".

Researchers studied gene expression in association with specific networks controlling feeding or defensive reflexes in the sea slug. To their surprise, they identified more than 100 genes similar to those associated with all major human neurological diseases and more than 600 genes controlling development, confirming that molecular and genomic events underlying key neuronal functions were developed in early animal ancestors and remained practically unchanged for more than 530 million years of independent evolution in the lineages leading to men or sea slugs.........

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December 27, 2006, 5:12 AM CT

Online Journal Combines Teaching Math

When instructors at Bronx-area community colleges applied for a National Science Foundation (NSF) grant to study how students think about fundamental concepts of calculus, they hoped to gain a better understanding of how college students learn mathematics. During the 4-year project, the teacher-researchers integrated ongoing research theories with classroom teaching. As a result, their project has evolved into a tool for helping students reason their way through complex calculus.

The researchers found that when students are actively engaged in the learning process, they are more likely to sort out the logic behind mathematical problems. A give-and-take method allows the students to voice their fears about the subject, express misconceptions, and participate in open discussions to reach a solution. Using an online, peer-reviewed teaching-research journal, the teacher-researchers give updates on their progress and share best practices and procedures. They invite other mathematics teachers and instructors to document their experiences and successes.

"The journal project contributes to NSF's goal to create an online network of learning environments and resources for science, technology, engineering, and mathematics education at all levels," said Lee L. Zia, program director for NSF's Division of Undergraduate Education. "Through a relatively easy mechanism to share best practices with the local community, the journal stimulates and supports research on learning, which is one of NSF's objectives".........

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December 27, 2006, 5:06 AM CT

Mixed Prairie Grasses Better Source Of Biofuel

Diverse mixtures of native prairie plant species have emerged as a leader in the quest to identify the best source of biomass for producing sustainable, bio-based fuel to replace petroleum.

A new study led by David Tilman, an ecologist at the University of Minnesota, shows that mixtures of native perennial grasses and other flowering plants provide more usable energy per acre than corn grain ethanol or soybean biodiesel and are far better for the environment. The research was supported by the National Science Foundation (NSF) and the University of Minnesota Initiative for Renewable Energy and the Environment.

"Biofuels made from high-diversity mixtures of prairie plants can reduce global warming by removing carbon dioxide from the atmosphere. Even when grown on infertile soils, they can provide a substantial portion of global energy needs, and leave fertile land for food production," Tilman said.

The findings appear in the Dec. 8, 2006, issue of the journal Science.

The is study based on 10 years of research at Minnesota's Cedar Creek Natural History Area, one of 26 NSF long-term ecological research (LTER) sites. It shows that degraded agricultural land planted with diverse mixtures of prairie grasses and other flowering plants produces 238 percent more bioenergy on average than the same land planted with various single prairie plant species, including switchgrass.........

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