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, 9:39 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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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 23, 2006, 11:04 AM CT

Two Different Crystalline Forms Of Aspirin

I am sure that you don't think of the crystalline structure of aspirin, when you have a headache and reach out for the aspirin bottle. At least that's what I do. This aspirin pill might relieve your headache, but the same aspirin is causing lots of headaches for some researchers.

The question that is causing problem for scientists is: is there another form on top of the long-known one? A team of scientists from Denmark, Germany, and India seems to have solved this controversial puzzle: yes, there is a second structure-but it does not exist as a pure form. "The two crystalline forms of aspirin are so closely related," explains the research team of Andrew D. Bond, Roland Boese and Gautam R. Desiraju in Angewandte Chemie, "that they form structures containing domains of both crystal types".

In 2004, computer calculations had indicated that while the long-known crystal structure of aspirin (form I) is definitely one of the most stable forms, another version might exist that is just as stable, though it had not yet been discovered-a clear challenge to researchers in the field. The difference between the proposed structures is slight: both have identical layers containing molecules grouped into pairs, but these layers are arranged differently in the two different structures. In 2005, researchers in the USA announced the discovery of the predicted structure (form II). But was this merely an artifact?........

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December 22, 2006, 5:18 AM CT

Strange Properties Of Superfluids

Princeton University electrical engineers are using lasers to shed light on the behavior of superfluids -- strange, frictionless liquids that are difficult to create and study. Their technique allows them to simulate experiments that are difficult or impossible to conduct with superfluids.

The odd behavior of particles in superfluids, which move together instead of at random, has been observed in light waves that pass through certain materials known as nonlinear crystals. The team relied on this underappreciated correlation to use laser light as a substitute, or model, for superfluids in experiments. Their results would be published in the January 2007 issue of Nature Physics.

Their work could heighten the current understanding of condensed matter physics as well as lead to advances in sensor technology, atomic trapping and optical communications.

"Once you realize you can use light to model a superfluid, a new world opens up," said Jason Fleischer, a Princeton assistant professor of electrical engineering who led the team. "An entire field of physics is interested in studying the dynamics of superfluids, but the experiments are difficult to do. It's a lot easier to conduct the experiments with lasers".

Fleischer and Princeton Engineering graduate students Wenjie Wan and Shu Jia validated their technique by generating results that matched data from previous superfluid experiments. They went on to study superfluid waves and interactions that had not been considered before, either theoretically or experimentally. For instance, they explored the collisions of circular waves similar to those created by drops of water falling into a puddle.........

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December 15, 2006, 4:50 AM CT

Scientists Make Liquid Crystal Discovery

What do milk, paint, ink and liquid crystals have in common? Colloids. Findings of Kent State University researchers indicate that manipulating the size of colloids, micron-sized or nanometer-sized particles, can produce huge changes in the material properties of liquid crystals.

In a recently published article in the scholarly journal Physical Review Letters, the researchers illustrate that when the concentration and size of the colloids and liquid crystals are properly tuned, the systems formed promise a new technique for synthesizing liquid crystals with specific molecular properties. The ferroelectric nanoparticles have a significant impact on the material properties of the liquid crystal host; meanwhile they are stable in the liquid crystals and invisible to naked eye.

Manipulation of these systems also leads to reduction in the amount of power mandatory to run liquid crystal displays, such as computer screens, and could result in creation of a range of different liquid crystal materials for a wide variety of applications.........

Posted by: Sarah      Permalink         Source

December 13, 2006, 4:24 AM CT

Some Snowflakes Can Look The Same

Snowflakes are one of the most recognizable and endearing symbols of winter. Their intricate shapes have been the inspiration for Christmas ornaments, jewelry and U.S. postage stamps. They are the subject of song, school projects and even scientific investigation, including a possible impact on global warming.

Jon Nelson, a researcher with Ritsumeikan University in Japan, has studied snowflakes for 15 years, and has some interesting insights into their delicate structures.

Is it true that no two snowflakes are alike?

The old adage that 'no two snowflakes are alike' may ring true for larger snowflakes, but it might not hold true for smaller, simpler crystals that fall before they've had a chance to fully develop. Regardless, snow crystals have tremendous diversity, partly due to their very high sensitivity to tiny temperature changes as they fall through the clouds.

How do snowflakes form?

A snowflake starts as a dust grain floating in a cloud. Water vapor in the air sticks to the dust grain and the resulting droplet turns directly into ice. And that's where the science kicks in.

First, the tiny ice crystal becomes hexagonal (six-sided). This shape originates from the chemistry of the water molecule, which consists of two hydrogen atoms bonded to an oxygen atom. Because of the angle of the water molecule and its hydrogen-bonding, the water molecules in a snowflake chemically bond to each other to form the six-sided flake. The flake eventually sprouts six tiny branches. Each of these branches grows to form side branches in a direction and shape that are influenced by the clustering of water molecules on the ice crystal surfaces.........

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December 4, 2006, 5:01 AM CT

From Light to Sodium Atoms

For the first time, tornado-like rotational motions have been transferred from light to atoms in a controlled way at the National Institute of Standards and Technology (NIST). The new quantum physics technique can be used to manipulate Bose-Einstein condensates (BECs), a state of matter of worldwide research interest, and possibly used in quantum information systems, an emerging computing and communications technology of potentially great power.

As published in the Oct. 27 issue of Physical Review Letters,* the research team transferred orbital angular momentum-essentially the same motion as air molecules in a tornado or a planet revolving around a star-from laser light to sodium atoms.

The NIST experiment completes the scientific toolkit for complete control of the state of an atom, which now includes the internal, translational, and rotational behavior. The rotational motion of light previously has been used to rotate particles, but this new work marks the first time the motion has been transferred to atoms in discrete, measurable units, or quanta. Other researchers, as well as the NIST group, previously have transferred linear momentum and spin angular momentum (an internal magnetic state) from light to atoms.

The experiments were performed with more than a million sodium atoms confined in a magnetic trap. The atoms were chilled to near absolute zero and in identical quantum states, the condition known as a Bose-Einstein condensate in which they behave like a single "super-atom" with a jelly-like consistency. The BEC was illuminated from opposite sides by two laser beams, one of them with a rotating doughnut shape. Each atom absorbed one photon (the fundamental particle of light) from the doughnut laser beam and emitted one photon in the path of the other laser beam, picking up the difference in orbital angular momentum between the two photons. The interaction of the two opposing lasers created a corkscrew-like interference pattern, inducing the BEC to rotate-picture a rotating doughnut, or a vortex similar to a hurricane.........

Posted by: Sarah      Permalink         Source

December 3, 2006, 9:06 PM CT

Beyond the bonds that bind

Scientists at the University of California, Santa Barbara have shown that, under the right circumstances, hydrogen can form multicenter bonds, where one hydrogen atom simultaneously bonds to as a number of as four or six other atoms. Tested for hydrogen in metal oxides, the discovery could have a broad range of technological impact. The research is available today in the advance online publication of Nature Materials.

Professor Chris G. Van de Walle and Project Scientist Anderson Janotti, both of the Materials Department of the College of Engineering at UC Santa Barbara, have shown that multi-coordinated hydrogen is a likely explanation for electronic conductivity in metal oxides. Metal oxides are widely used in everything from sunscreen to sensors.

Hydrogen, the simplest of the elements (consisting of one proton and one electron) is typically expected to exhibit simple chemistry when forming molecules or solids. Hydrogen atoms almost always form a single bond to just one other atom, leading to a two-center bond with two electrons. Exceptions to the rule are rare; there are only a few cases when hydrogen bonds simultaneously to two other atoms, forming a three-center bond.

Hydrogen can replace an oxygen atom and form a multicenter bond with adjacent metal atoms. For example, in ZnO, hydrogen equally bonds to the four surrounding Zn atoms, becoming fourfold coordinated. These multicenter bonds are highly stable and explain previously puzzling variations in conductivity as a function of temperature and oxygen pressure. The results suggest that hydrogen can be used as a substitutional dopant in oxides, a concept that is counterintuitive and should be of wide interest to researchers.........

Posted by: Sarah      Permalink         Source

November 30, 2006, 5:08 AM CT

Mystery About Stradivarius Violins Solved

Answering a question that has lingered for centuries, a team of scientists has proved that chemicals used to treat the wood used in Stradivarius and Guarneri violins are the reasons for the distinct sound produced by the world-famous instruments.

The conclusions, published in the current issue of Nature magazine, have confirmed 30 years of work into the subject by Joseph Nagyvary, professor emeritus of biochemistry at Texas A&M University, who was the first to theorize that chemicals not necessarily the wood created the unique sound of the two violins. Nagyvary teamed with collaborators Joseph DiVerdi of Colorado State University and Noel Owen of Brigham Young University on the project.

This research proves unquestionably that the wood of the great masters was subjected to an aggressive chemical treatment and the chemicals most likely some sort of oxidizing agents had a crucial role in creating the great sound of the Stradivarius and the Guarneri, Nagyvary says.

Like many discoveries, this one could have been accidental. Perhaps the violin makers were not even aware of the acoustical effects of the chemicals. Both Stradivari and Guarneri wanted to treat their violins to prevent worms from eating away the wood. They used some chemical agents to protect the wood from worm infestations of the time, and the unintended consequence from these chemicals was a sound like none other, he adds.........

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