August 20, 2007, 7:39 AM CT

What Are Those Actinides Doing?

Scientists at Pacific Northwest National Laboratory are uniting theory, computation and experiment to discover exactly how heavy elements, such as uranium and technetium, interact in their environment.

As part of that effort, researchers have combined sensitive experimental measurements with fi rst principle electronic structure calculations to measure, and to really understand, the structural and bonding parameters of uranyl, the most common oxidation state of uranium in systems containing water.

The insights were achieved by PNNL scientist Bert de Jong and associates Gary Groenewold of Idaho National Laboratory and Michael Van Stipdonk of Wichita State University, employing the supercomputing resources of the William R. Wiley Environmental Molecular Sciences Laboratory (www.emsl.pnl.gov), a Department of Energy national scientifi c user facility located at PNNL.

The large number and behavior of electrons in heavy elements makes most of them extremely diffi cult to study. De Jong said that advancements in computing power and theory are enabling computational actinide chemistry to contribute significantly to the understanding and interpretation of experimental chemistry data, as well as to predicting the chemical and physical properties of heavy transition metal, lanthanide and actinide complexes......... Posted by: Sarah      Read more         Source

August 7, 2007, 10:35 PM CT

Where chemistry happens for the very first time

Picture a cool place, teeming with a multitude of hot bodies twirling about in rapidly changing formations of singles and couples, partners and groups, constantly dissolving and reforming.

If you were thinking of the dance floor in a modern nightclub, think again.

It's a description of the shells around dying stars, the place where newly formed elements make compounds and life takes off, said Katharina Lodders, Ph.D., research associate professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis.

Chemistry for the very first time

"The circumstellar environment is where chemistry happens for the very first time," said Lodders. "It's the first place a newly synthesized element can do chemistry. It's a supermarket of things from dust to gas and dust grains to molecules and atoms. The circumstellar shells enable a chemistry that produced grains older than our sun itself. It's generated some popular interest, and this year marks the 20th anniversary of the presolar grain discoveries".

After the discovery of presolar diamonds in a meteorite in 1987 - the first stardust found in a meteorite - researchers at Washington University in St. Louis have been prominent in finding and analyzing pre-solar grains made of silicon carbide, diamonds, corundum, spinel, and silicates. The latest discovery - a silicate grain that formed around a foreign star and became incorporated into a comet in our solar system - was captured and returned by the STARDUST space mission in 2006......... Posted by: Sarah      Read more         Source

August 3, 2007, 10:02 PM CT

Thousands of Atoms Swap 'Spins' in Quantum Square Dance

Physicists at the National Institute of Standards and Technology (NIST) have induced thousands of atoms trapped by laser beams to swap "spins" with partners simultaneously. The repeated exchanges, like a quantum version of swinging your partner in a square dance but lasting a total of just 10 milliseconds, might someday carry out logic operations in quantum computers, which theoretically could quickly solve certain problems that today's best supercomputers could not solve in years.

The atomic dance, described in the July 26 issue of Nature,* advances prospects for the use of neutral atoms as quantum bits (qubits) for storing and processing data in quantum computers. Thanks to the peculiarities of quantum mechanics, nature's rule book for the smallest particles of matter and light, quantum computers might provide extraordinary power for applications such as breaking today's most widely used encryption codes. Neutral atoms are among about a dozen systems being reviewed around the world as qubits; their weak interactions with the environment may help to reduce computing errors.

The NIST experiments demonstrated the essential part of a so-called swap operation, in which atom partners exchange their internal spin states, trading an "up" spin (notionally a binary 1) for a "down" spin (binary 0.) Unlike classical bits, which would either swap or not, quantum bits can be simultaneously in an unusual state of having swapped and not swapped at the same time. Under these conditions, spin swapping has the effect of "entangling" the pairs, a quantum phenomenon that links the atoms' properties even when they are physically separated. Entanglement is one of the features that make quantum computers potentially so powerful. The swapping process is a way of creating logical connections among data, crucial in any computer......... Posted by: Sarah      Read more         Source

August 3, 2007, 5:15 AM CT

New oxidation methods streamline synthesis

One of the fundamental challenges facing organic synthesis in the 21st century is the need to significantly increase the efficiency with which carbon frameworks can be constructed and functionalized. Chemists at the University of Illinois are helping to meet this challenge by developing a class of carbon-hydrogen catalysts that are highly selective, reactive and tolerant of other functionality.

The catalysts also offer a new strategy for streamlining the synthesis of important compounds, including drugs and pharmaceuticals, by avoiding the functional group manipulations mandatory for working with oxidized materials.

"We are creating a toolbox of catalytic reactions that allow us to go directly from a carbon-hydrogen bond to a carbon-oxygen bond or to a carbon-nitrogen bond," said M. Christina White, a professor of chemistry at Illinois. "By offering fewer steps, fewer functional group manipulations and higher yields, this toolbox will change the way chemists make molecules".

Currently, chemists must make molecules by beginning with something that is already oxidized. But, having to start with that functionality means it must be carried - and protected - throughout the entire synthetic sequence. And that costs reagents, time, money and manpower, in addition to being inherently inefficient......... Posted by: Sarah      Read more         Source

July 23, 2007, 6:55 PM CT

A novel molecular dictator 'with a conscience' discovered

UNSW scientists have uncovered an important naturally occurring mechanism in the body where "bad" cells that cause blockages in our blood vessels are kept under strict growth control, while "good" cells that keep our blood vessels free of clots and growths are left unaffected.

The discovery is expected to benefit those who will need heart coronary bypass surgery, an angioplasty - the mechanical widening of a narrowed or totally blocked blood vessel - or will undergo haemodialysis.

Professor Levon Khachigian, from UNSW's Centre for Vascular Research, who previously pioneered "molecular assassin" drug technology, describes this novel mechanism he discovered as "a molecular dictatorship with a conscience".

"The dictator is a specific gene suppressor called YY1, which has the therapeutically appealing capacity to differentiate between certain cell types when it goes about its activity," says Professor Khachigian.

This key finding has just been reported in the world's premier cardiovascular research journal, Circulation Research.

Professor Khachigian's research provides new hope in tackling the global problems of coronary bypass graft failure, and restenosis - the closing or narrowing of an artery that was previously opened by a procedure such as angioplasty......... Posted by: Sarah      Read more         Source

July 12, 2007, 8:28 PM CT

Masses of methane escape from Italy

Italy is the seventh largest European producer of natural gas, with reservoir volumes approaching 2200 billion cubic meters (2877 billion cubic yards). Of this, 74 percent formed through microbial decay of organic matter (biogenic gas), 14 percent formed by thermal breakdown of organic material at greater depth (thermogenic), and 12 percent is mixed. Because most gas fields occur in areas influenced by tectonics, gas migration to the surface is widespread, leading to over a thousand seeps, including mud volcanoes and dry seeps.

Etiope et al. assess the gas origin from all main seeps still active today. Noting that methane is a potent greenhouse gas, they seek to quantify its flux to the atmosphere, including contributions from diffuse soil degassing. They find that 80 percent of the seeps release thermogenic gas, and that mud volcano gas is generally lighter (more methane, less ethane and propane) than its original reservoir gas. Dry seeps, instead, maintain the same alkane composition as their reservoirs. The authors estimate that methane emission may reach levels of hundreds of thousands tons per year, comparable to national emissions from the fossil fuel industry......... Posted by: Sarah      Read more         Source

July 12, 2007, 8:03 PM CT

Speed bumps less important than potholes for graphene

For electrical charges racing through an atom-thick sheet of graphene, occasional hills and valleys are no big deal, but the potholessingle-atom defects in the crystaltheyre killers. Thats one of the conclusions reached by scientists from the National Institute of Standards and Technology (NIST) and the Georgia Institute of Technology who created detailed maps of electron interference patterns in graphene to understand how defects in the two-dimensional carbon crystal affect charge flow through the material. The results, appearing in the July 13 issue of Science*, have implications for the design of graphene-based nanoelectronics.

A single layer of carbon atoms tightly arranged in a honeycomb pattern, graphene was long believed to be an interesting theoretical concept that was impossible in practiceit would be too unstable, and crumple into some other configuration. The discovery, in 2004, that graphene actually could exist touched off a rush of experimentation to explore its properties. Graphene has been described as a carbon nanotube unrolled, and shares some of the unique properties of nanotubes. In particular, its a so-called ballistic conductor, meaning that electrons flow through it at high speed, like photons through a vacuum, with virtually no collisions with the atoms in the crystal. This makes it a potentially outstanding conductor for wires and other elements in nanoscale electronics......... Posted by: Sarah      Read more         Source

July 10, 2007, 5:27 AM CT

Invisible gases form most organic haze in urban, rural areas

A new study involving the University of Colorado at Boulder shows that invisible, reactive gases hovering over Earth's surface, not direct emissions of particulates, form the bulk of organic haze in both urban and rural areas around the world.

A number of science and health professionals have believed sources that spew soot and other tiny particles directly into the air were the primary culprit in the formation of organic haze. But a new study by scientists at CU-Boulder's Cooperative Institute for Research in Environmental Sciences show aerosols formed chemically in the air account for about two-thirds of the total organic haze in urban areas and more than 90 percent of organic haze in rural areas.

The study was led by Qi Zhang, a former CIRES scientist now at the Atmospheric Sciences Research Center at State University of New York, Albany and CIRES researcher Jose-Luis Jimenez. The study was reported in the July 7 online issue of Geophysical Research Letters.

The researchers compared concentrations of directly emitted, or primary, aerosols with chemically formed, or secondary aerosols. They surveyed urban areas, areas downwind of urban areas and rural areas from 37 sites in 11 countries.

"What we're seeing is that concentrations of secondary organic aerosols decrease little downwind from urban areas," said Jimenez, also an assistant professor in CU-Boulder's chemistry and biochemistry department. "That tells us there has to be an extended source or continuous formation for the pollution"......... Posted by: Sarah      Read more         Source

June 13, 2007, 1:30 PM CT

Lung and bladder cancer after arsenic exposure

Arsenic exposure appears to continue causing lung and bladder cancer deaths years after exposure ends, according to a study published online June 12 in the Journal of the National Cancer Institute

Arsenic is a known cause of lung and bladder cancer, but researchers dont yet know how long cancer risk remains elevated after arsenic exposure. The drinking water in a region of northern Chile became contaminated with very high amounts of arsenic beginning in 1958. In the 1970s, construction of water treatment plants in the region led to a decline in arsenic concentration. This sudden rise and fall of arsenic levels gave researchers the opportunity to investigate the period between first and last exposure to high levels of arsenic and subsequent mortality due arsenic-related cancers, such as bladder and lung cancer.

Guillermo Marshall, Ph.D., of Pontificia Universidad Catlica de Chile in Santiago and colleagues including collaborators from the University of California, Berkeley, investigated bladder and lung cancer death rates in the region between 1950 and 2000 and compared them with data from a similar region farther south, where the water was not contaminated.

Lung and bladder cancer mortality rates in the area with arsenic-contaminated drinking water began to rise about 10 years after arsenic levels rose. They then continued to climb, peaking between 10 and 20 years after the arsenic levels dropped. At the peak, lung cancer deaths among men and women in the contaminated region were about three times higher than in the control region, while bladder cancer deaths were six times higher in men and 14 times higher in women. The lag time between exposure to a carcinogen and the peak of cancer deaths is usually difficult to determine, but the size of the study and the record of arsenic exposure aided the researchers......... Posted by: Sarah      Read more         Source

June 10, 2007, 9:11 PM CT

Nitrate in Lake Superior

Nitrate levels in Lake Superior, which have been rising steadily over the past century, are about 2.7 percent of the way toward making the lake's water unsafe to drink, as per a research studyby University of Minnesota (UMN) researchers.

The study, funded by the National Science Foundation (NSF), is published online this week in the journal Geophysical Research Letters.

The complexity of the causes underlying the increase makes it difficult to predict when the water could become unhealthy. The trend is a concern because Lake Superior contains 10 percent of the Earth's supply of surface fresh water.

Eventhough everyone is exposed to small, harmless amounts of nitrate from eating fruits and vegetables, nitrate contamination of drinking water can expose people to harmful levels.

Too much nitrate can reduce blood levels of oxygen, which poses a risk to infants and children or adults with lung or cardiovascular disease. Consuming excess nitrate over long periods of time is also suspected of causing cancer.

A compound made from nitrogen and oxygen, nitrate is a component of agricultural fertilizers and is generated by fossil fuel combustion. Nitrate in Lake Superior has increased about five-fold since the earliest measurements in 1906......... Posted by: Tyler      Read more         Source