October 23, 2007, 10:02 PM CT

Gerhard Ertl wins Nobel Prize in Chemistry

"The Max Planck researcher has succeeded in providing a detailed description of how chemical reactions take place on solid surfaces," said the Swedish Academy of Sciences today in Stockholm in a statement.

The prize, which Ertl does not have to share with any other colleague, is worth roughly 1.1 million euros. "I have the highest regard for Mr Ertl - not only as an outstanding scientist but also as an individual of great integrity, whose commitment to the Max Planck Society has been invaluable", said Peter Gruss, President of the Max Planck Society in Munich on Wednesday. "This award is a special gift for Mr Ertl, who also celebrates his 71st birthday today".

How fuel cells function.

"Gerhard Ertl has laid the foundations for understanding industrial catalysts and catalytic processes", said Ferdi Schüth of the Max Planck Institute for Coal Research, a colleague of the Nobel Prize laureate. "His research helps to explain such varied processes as how fuel cells function and catalysts in automobiles work." This science is important in a number of industrial processes, such as in the production of artificial fertilizers. Surface chemistry can even explain the thinning of the ozone layer.

"I was at a loss for words".

Ertl was overjoyed. "I never expected to win," he said. While he had been aware that he was on the list of candidates, he was nevertheless at a loss for words after hearing that he had won the Nobel Prize. The Prize Committee gave him 20 minutes to collect himself and to get ready for the press. "Now the phones are ringing off the hook". All his staff members gathered outside his office to toast the news with him with a glass of champagne......... Posted by: Sarah      Read more         Source

October 22, 2007, 8:44 PM CT

Rise in atmospheric CO2 accelerates as economy grows

Human activities are releasing carbon dioxide faster than ever, while the natural processes that normally slow its build up in the atmosphere appear to be weakening. These conclusions are drawn in a new study in the early online edition of the Proceedings of the National Academy of Sciences,* October 22-26. The report states that together, these effects characterize a carbon cycle that is generating stronger-than-expected climate forcing sooner than expected.

Between 2000 to 2006, human activities such as burning fossil fuels, manufacturing cement, and tropical deforestation contributed an average of 4.1 billion metric tons of carbon to the atmosphere each year, yielding an annual growth rate for atmospheric carbon dioxide of 1.93 parts per million (ppm). This is the highest since the beginning of continuous monitoring in 1959, states the report. The growth rate of atmospheric carbon dioxide is significantly larger than those for the 1980s and 1990s, which were 1.58 and 1.49 ppm per year, respectively. The present atmospheric concentration of carbon dioxide is 381 ppm, the largest concentration in the last 650,000 years, and probably in the last 20 million years.

While the worldwide acceleration in carbon dioxide emissions had been previously noted, the current analysis provides insights into its causes. The new twist here is the demonstration that weakening land and ocean sinks are contributing to the accelerating growth of atmospheric CO₂, says co-author Chris Field, director of the Carnegie Institutions Department of Global Ecology......... Posted by: Jaison      Read more         Source

October 21, 2007, 10:09 PM CT

The solution to a 7-decade mystery

A Florida State University researcher has helped solve a scientific mystery that stumped chemists for nearly seven decades. In so doing, his teams findings may lead to the development of more-powerful computer memories and lasers.

Naresh S. Dalal, the Dirac Professor of Chemistry and Biochemistry at FSU, recently collaborated with three colleagues, Jorge Lasave, Sergio Koval and Ricardo Migoni, all of the Universidad Nacional de Rosario in Argentina, to determine why a certain type of crystal known as ammonium dihydrogen phosphate, or ADP, behaves the way it does.

ADP was discovered in 1938, Dalal said. It was observed to have some unusual electrical properties that werent fully understood -- and for nearly 70 years, researchers have been perplexed by these properties. Using the supercomputer at SCRI (FSUs Supercomputer Computations Research Institute), we were able to perform in-depth computational analyses that explained for the very first time what causes ADP to have these unusual properties.

ADP, like a number of crystals, exhibits an electrical phenomenon known as ferroelectricity. Ferroelectric materials are analogous to magnets in that they maintain a positively charged and a negatively charged pole below a certain temperature that is characteristic for each compound......... Posted by: Sarah      Read more         Source

October 17, 2007, 8:27 PM CT

Pine bark extract boosts nitric oxide production

A study would be reported in the October edition of High blood pressure Research reveals Pycnogenol, (pic-noj-en-all), an antioxidant plant extract from the bark of the French maritime pine tree, helps individuals by enhancing healthy nitric oxide (NO) production which leads to an increase in blood flow and oxygen supply to muscles.

Nitric oxide, a key cardiovascular chemical produced by the body, increases blood flow that serves to deliver more nutrients and oxygen to the muscles, helping muscles to cope with increased physical activity and build when subjected to regular elevated labor.

This study suggests that when taking Pycnogenol, more NO is provided in response to neurotransmitters allowing for better expansion of arteries to carry more blood. This process serves to meet the enhanced oxygen demand of the performing muscle and avoid anaerobic metabolism, said Dr. Yukihito Higashi, lead researcher of the study. These results also lead me to determine that Pycnogenol will be a useful natural alternative treatment in various diseases in which oxidative stress is involved in the pathogenesis.

The double-blind, randomized, placebo study was held at the Hiroshima University Graduate School of Biomedical Sciences in Japan. Every day for two weeks young healthy men either took 180 mg Pycnogenol or a placebo. To identify Pycnogenols effect on the release of NO, an inhibitor of the amino acid L-arginine was infused in patients, which restricts the expansion of arteries in response to the neurotransmitter acytelcholine......... Posted by: Sarah      Read more         Source

Wed, 17 Oct 2007 01:11:25 GMT

Michaelis-Menten enzyme kinetics

Enzymes are the workhorses of the cell. They are proteins which help facilitate reactions, such as RNA polymerase adding nucleotides to form new strands of RNA. The polymerase is the enzyme (E), the nucleotides are the substrate (S), which react to form a product (P), the newly formed RNA strand.

It can often be the case that there are very low copy numbers of enzymes in the cell, meaning only one to a handful of a specific kind of enzyme. It is also possible that there is significant substrate present. You might then wonder, how fast can the enzyme of interest, given basically unlimited substrate, carry out its reaction? Let’s simplify the situation and assume only one enzyme in a cell filled with substrate*. The below treatment was first outlined by Haldane, and then by Leonor Michaelis and Maud Menten.

The enzymatic reaction described above looks like this:

where the concentration of the substrate, cS, comes into play, and it is assumed that the second step, ES reacting to make product P, is irreversible. Thinking of the reaction in terms of probabilities (which we will denote using lowercase p), if the enzyme is unbound there is a probability per unit time cSk1 of binding a substrate, if the enzyme is bound with the substrate there is a probability per unit time of k2 of reacting to form product, or probability per unit time k-1 of returning back to its unbound state. Explicitely,

In the steady-state (dpE/dt = 0), you can solve for the probability of being in the enzyme-substrate complex:

The rate at which product is created is then k2pES as per our original reaction equation, and multiplying by the enzyme concentration (in our case just a single enzyme) gives you the velocity of the reaction.

We can simplify the formula further by introducing these two substitutions:

where KM is called the Michaelis constant, and is a measure of concentration, while vmax is a measure of the rate of change of concentration. Substition gives the famous Michaelis-Menten rule:

This rule helps explain the observed kinetics of some enzyme reactions, such as the Maud Menten (free link to the paper at the bottom of the post).

So, why the primer on enzyme kinetics?

Maud Menten

Because Maud Menten and I are schoolmates, so to speak!

* This treatment is based on P. Nelson’s Biological Physics, Ch. 10. Posted by: PhilipJ      Read more     Source

October 10, 2007, 7:10 PM CT

Assessing health risks from chemicals

Determining how thousands of chemicals found in the environment may be interacting with the genes in your body to cause disease is becoming easier because of a new field of science called toxicogenomics. A new report issued today by the National Academies of Sciences (NAS) recognizes the importance of toxicogenomics in predicting effects on human health and recommends the integration of toxicogenomics into regulatory decision making. The NAS report was commissioned by the National Institute of Environmental Health Sciences (NIEHS) part of the National Institutes of Health (NIH) and a leader in the development of toxicogenomic technologies.

Toxicogenomic technologies provide tools to better understand the mechanisms through which environmental agents initiate and advance disease processes. They can also provide important information to help identify individuals that are more susceptible to disease risks posed by certain environmental agents than the general population.

Using toxicogenomic technologies will open the door for public health decision makers who need to decide in a timely and accurate manner what chemicals are safe and which ones are not, says Christopher Portier, Ph.D., Associate Director, NIEHS and Director, Office of Risk Assessment Research......... Posted by: Sarah      Read more         Source

October 4, 2007, 9:48 PM CT

The Structure Of Microcrystals

Microcrystals take the form of tiny grains, so small that they resemble a powder. How can we determine their structure? Until today, the technique of X-ray diffraction, normally used to study crystals, was not an appropriate solution. For the first time, scientists from the ESRF and the CNRS have used X-ray diffraction to determine the structure of microcrystal grains of only one cubic micrometre in size. They gained a factor of a thousand on the size of the analysable samples thanks to new equipment created at the ESRF. This breakthrough opens up new possibilities of research to chemists, physicists and biologists.

The properties of a crystal are determined by the arrangement of its atom in space, its crystalline structure. Researchers use X-ray or neutron diffraction to study crystalline structure when the size of the crystal is more than 10 cubic micrometres. Below this limit, the solid material is considered a powder. Researchers can apply powder diffraction to analyse such a material but this technique is not easy to exploit. Moreover, powder diffraction can only be used for materials with grain sizes of less than three millionths of a cubic micrometre. Due to these limitations, a determination of the structure of new synthetic solids in powder form is not always possible because the crystals are too small......... Posted by: Sarah      Read more         Source

Wed, 03 Oct 2007 11:39:31 GMT

Superoxide Dismutase

We can’t live without oxygen. Our cells rely on oxygen as the final acceptor of electrons in respiration, allowing us to extract far more energy from food than would be possible without oxygen. But oxygen is also a dangerous compound. Reactive forms of oxygen, such as superoxide (oxygen with an extra electron), leak from the respiratory enzymes and wreak havoc on the cell. This superoxide can then cause mutations in DNA or attack enzymes that make amino acids and other essential molecules. This is a significant problem: one study showed that for every 10,000 electrons transferred down the respiratory pathway in Escherichia coli cells, about 3 electrons end up on superoxide instead of the proper place. To combat this potential danger, most cells make superoxide dismutase (SOD, shown here from PDB entry 2sod), an enzyme that detoxifies superoxide.

As you might guess from its name, SOD dismutes superoxide. Dismutation is a term that refers to a special type of reaction, where two equal but opposite reactions occur on two separate molecules. SOD takes two molecules of superoxide, strips the extra electron off of one, and places it on the other. So, one ends up with an electron less, forming normal oxygen, and the other ends up with an extra electron. The one with the extra electron then rapidly picks up two hydrogen ions to form hydrogen peroxide. Of course, hydrogen peroxide is also a dangerous compound, so the cell must use the enzyme catalase to detoxify it.

More from David Goodsell here. Posted by: PhilipJ      Read more     Source

September 26, 2007, 8:31 PM CT

Pinning Down Spin of Surface Atoms

Researchers who dream of shrinking computers to the nanoscale look to atomic spin as one possible building block for both processor and memory, yet setting the spin of an atom, let alone measuring it, has been a challenge.

Now, University of California, Berkeley, physicists have succeeded in measuring the spin of a single atom, moving one step closer to quantum computers and "spintronic" devices built from nanoscale transistors based on atomic spin.

"From a technical point of view, this demonstrates a new ability to engineer, fabricate and measure spin-polarized nanostructures at the single atom level," said Michael F. Crommie, UC Berkeley professor of physics. "Now that I can see an atom's spin, I can ask, 'What can I do with that atomic spin? Can I manipulate it? Can I use it, change it?' This means we can now start incorporating it into other structures."

Crommie and colleagues at UC Berkeley and the Center for Computational Materials Science (CCMS) at the Naval Research Laboratory in Washington, D.C., recently reported their success in the journal Physical Review Letters.

At the core of today's digital computers are billions of tiny transistor circuits that, because they can exist in two states, are used to represent the binary digits, or "bits" 0 and 1, which are the basis of all computer manipulations......... Posted by: Sarah      Read more         Source

September 23, 2007, 11:38 AM CT

A better definition for the kilogram?

How much is a kilogram?.

It turns out that nobody can say for sure, at least not in a way that wont change ever so slightly over time. The official kilogram a cylinder cast 118 years ago from platinum and iridium and known as the International Prototype Kilogram or Le Gran K has been losing mass, about 50 micrograms at last check. The change is occurring despite careful storage at a facility near Paris.

Thats not so good for a standard the world depends on to define mass.

Now, two U.S. professors a physicist and mathematician say its time to define the kilogram in a new and more elegant way that will be the same today, tomorrow and 118 years from now. Theyve launched a campaign aimed at redefining the kilogram as the mass of a very large but precisely-specified number of carbon-12 atoms.

Our standard would eliminate the need for a physical artifact to define what a kilogram is, said Ronald F. Fox, a Regents Professor Emeritus in the School of Physics at the Georgia Institute of Technology. We want something that is logically very simple to understand.

Their proposal is that the gram 1/1000th of a kilogram would henceforth be defined as the mass of exactly 18 x 14074481 (cubed) carbon-12 atoms.

The proposal, made by Fox and Theodore P. Hill a Professor Emeritus in the Georgia Tech School of Mathematics first assigns a specific value to Avogadros constant. Proposed in the 1800s by Italian scientist Amedeo Avogadro, the constant represents the number of atoms or molecules in one mole of a pure material for instance, the number of carbon-12 atoms in 12 grams of the element. However, Avogadros constant isnt a specific number; its a range of values that can be determined experimentally, but not with enough precision to be a single number......... Posted by: Sarah      Read more         Source