Tue, 04 Dec 2007 01:17:45 GMT

Understanding The Periodic Table

You''ve probably seen this table before. It''s one of the most important tools for understanding chemistry.

Go through it piece by piece and soon enough you''ll not only understand how it works, you''ll be able to use it to figure out how and why elements interact to make the world you see around you. Posted by: Gerard      Read more     Source

December 2, 2007, 9:22 PM CT

The best sources of geothermal energy

With fossil fuel sources depleting and global warming on the rise, exploring alternative means of power for humans is a necessary reality. Now, looking to the sky, relying on the wind or harnessing water power are not the only remaining options. Deep within Earth is an untapped source of energy: geothermal energy.

It has been estimated that within the continental United States, there is a sizable resource of accessible geothermal energy about 3,000 times the current annual U.S. consumption.

Two important reasons this storehouse of energy has not been tapped is that locating the specific energy hot spots is difficult and expensive.

Since a number of geothermal resources are hidden, that is, they do not show any clear indications of their presence at the surface, locating them by just using observations made at the surface is difficult, explains Matthijs van Soest, associate research professional at the Noble Gas Geochemistry and Geochronology Laboratory within the School of Earth and Space Exploration at Arizona State University.

Often when people thought there might be a geothermal resource below the surface the only way to determine if their assumption was correct was drilling and drilling is extremely expensive, he says.

Now, research by van Soest and B. Mack Kennedy at Lawrence Berkeley National Laboratory reveals that geothermal exploration doesnt have to be high-priced......... Posted by: Sarah      Read more         Source

December 2, 2007, 9:12 PM CT

Between water and rock

Water chemistry and mineralogy are scientific fields that have been around long enough to develop extensive knowledge and technologies. The boundary of water and rock, however, is not a thin wet line but the huge new field of nanoparticle science.

Researchers are discovering that aquatic nanoparticles, from 1 to 100 nanometers, influence natural and engineered water chemistry and systems differently than similar materials of a larger size. Nanoparticles are in an awkward intermediate state, between elements dissolved in water and minerals that you can hold in your hand, said Michael Hochella Jr., University Distinguished Professor of geosciences at Virginia Tech. The nanoscale represents a transition zone. For instance, the electronic, magnetic, and optical properties at the atomic, nano, and bulk scales are all different.

The cover story of the recent issue of the Royal Society of Chemistrys Journal of Environmental Monitoring (www.rsc.org/Publishing/Journals/em/) offers a critical review of the emerging field of Aquatic environmental nanoparticles. Written by Virginia Tech Ph.D. students Nicholas S. Wigginton of Holt, Mich., and Kelly (Plathe) Haus of Rochester, Minn., and Hochella, the article looks at recent advances in identifying nanoparticles in water and in understanding their properties and reactivity......... Posted by: Sarah      Read more         Source

November 29, 2007, 9:10 PM CT

Helium Isotopes Point to New Sources of Geothermal Energy

Currently, most developed geothermal energy comes from regions of volcanic activity, such as The Geysers in Northern California. The potential resources identified by Kennedy and van Soest arise not from volcanism but from the flow of surface fluids through deep fractures that penetrate the earth's lower crust, in regions far from current or recent volcanic activity. The scientists report their findings in the November 30, 2007 issue of Science.

"A good geothermal energy source has three basic requirements: a high thermal gradient - which means accessible hot rock - plus a rechargeable reservoir fluid, commonly water, and finally, deep permeable pathways for the fluid to circulate through the hot rock," says Kennedy, a staff scientist in Berkeley Lab's Earth Sciences Division. "We believe we have found a way to map and quantify zones of permeability deep in the lower crust that result not from volcanic activity but from tectonic activity, the movement of pieces of the Earth's crust."

Kennedy and van Soest made their discovery by comparing the ratios of helium isotopes in samples gathered from wells, surface springs, and vents across the northern Basin and Range. Helium-three, whose nucleus has just one neutron, is made only in stars, and Earth's mantle retains a high proportion of primordial helium-three (in comparison to the minuscule amount found in air) left over from the formation of the solar system. Earth's crust, conversely, is rich in radioactive elements like uranium and thorium that decay by emitting alpha particles, which are helium-four nuclei. Thus a high ratio of helium-three to helium-four in a fluid sample indicates that much of the fluid came from the mantle......... Posted by: Sarah      Read more         Source

November 21, 2007, 4:50 AM CT

Surface Orbital "Roughness" in Manganites

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have shown that in a class of materials called manganites, the electronic behavior at the surface is considerably different from that found in the bulk. Their findings, which were published online in the November 18, 2007, issue of Nature Materials, could have implications for the next generation of electronic devices, which will involve increasingly smaller components.

As devices shrink, the proportion of surface area grows compared to the material's volume. Therefore, it's important to understand the characteristics of a material's surface in order to predict how those materials behave and how electrons will travel across an interface, said Brookhaven physicist John Hill.

Hill and his fellow scientists were especially interested in how the outer electrons of atoms in a so-called manganite material are arranged. Manganites - consisting of a rare-earth element such as lanthanum combined with manganese and oxygen - show a huge change in electrical resistance when a magnetic field is applied. Taking advantage of this "colossal magnetoresistance effect" could be the key to developing advanced magnetic memory devices, magnetic field sensors, or transistors.

The research team, which also includes researchers from KEK (Japan), CNRS (France), Ames Laboratory, and Argonne National Laboratory, used x-ray scattering at Brookhaven's National Synchrotron Light Source and Argonne's Advanced Photon Source to study the orbital order - the arrangement of electrons in the outermost shell - of the material at the surface and in its bulk......... Posted by: Kevin      Read more         Source

November 8, 2007, 10:05 PM CT

Smile, protons, you're on camera

Radioactivity, discovered more than 100 years ago and studied by physicists ever since, would seem to be a relatively closed subject in science. However, since the 1960s, the pursuit of at least one open question about how nuclei spontaneously eject various particles has continued to nag experimentalists, largely because of an inability to make precise measurements of fleeting, exotic nuclei.

In a paper published this week in Physical Review Letters, an international collaboration of researchers, led by Marek Pfutzner, a physicist from Warsaw University in Poland, takes several steps toward an answer. The researchers describe a first-ever success in peering closely at radioactive decay of a rare iron isotope at the ragged edge of the known nuclear map. The tools used to achieve this result include a novel combination of advanced physics equipment and imaging technology that is found in most off-the-shelf digital cameras.

"We have proved in a direct and clear way that this extremely neutron-deficient nucleus disintegrates by the simultaneous emission of two protons," write the authors.

Pfutzner and his collaborators set out to better understand an exotic form of radioactivity -- two-proton emissions from iron-45, a nucleus with 26 protons and 19 neutrons. The stable form of iron that is most abundant on Earth has 26 protons and 30 neutrons. One possibility was that the iron-45 isotope might occasionally release an energetically linked two-proton pair, known as a diproton. Other possibilities were that the protons, whether emitted in quick succession or simultaneously, were unlinked......... Posted by: Sarah      Read more         Source

November 7, 2007, 6:59 PM CT

LHC completes the circle

At a brief ceremony deep under the French countryside today, CERN1 Director General Robert Aymar sealed the last interconnect in the world's largest cryogenic system, the Large Hadron Collider (LHC). This is the latest milestone in commissioning the LHC, the world's most powerful particle accelerator.

The LHC's cryogenic system has the task of cooling some 36 800 tonnes of material to a temperature of just 1.9 degrees above absolute zero (-271.3 degree C), colder than outer space. To do this, over 10 000 tonnes of liquid nitrogen and 130 tonnes of liquid helium will be deployed through a cryogenic system including over 40 000 leak-tight welds. Today's ceremony marks the end of a two year programme of work to connect all the main dipole and quadrupole magnets in the LHC. This complex task included both electrical and fluid connections.

"This is a huge accomplishment," said Lyn Evans, LHC project leader. "Now that it is done, we can concentrate on getting the machine cold and ready for physics."

The LHC is a circular machine, 27 kilometres around and divided into eight sectors, each of which can be cooled down to its operating temperature of 1.9 degrees above absolute zero and powered-up individually. One sector was cooled down, powered and warmed up in the first half of 2007. This was an important learning process, allowing subsequent sectors to be tested more quickly......... Posted by: Sarah      Read more         Source

November 7, 2007, 4:49 AM CT

Enhancing Mother Nature's carbon handling mechanism

Taking a page from Nature herself, a team of scientists developed a method to enhance removal of carbon dioxide from the atmosphere and place it in the Earth's oceans for storage.

Unlike other proposed ocean sequestration processes, the new technology does not make the oceans more acid and may be beneficial to coral reefs. The process is a manipulation of the natural weathering of volcanic silicate rocks.

Reporting in today's (Nov. 7) issue of Environmental Science and Technology, the Harvard and Penn State team explained their method.

"The technology involves selectively removing acid from the ocean in a way that might enable us to turn back the clock on global warming," says Kurt Zenz House, graduate student in Earth and planetary sciences, Harvard University. "Essentially, our technology dramatically accelerates a cleaning process that Nature herself uses for greenhouse gas accumulation".

In natural silicate weathering, carbon dioxide from the atmosphere dissolves in fresh water and forms weak carbonic acid. As the water percolates through the soil and rocks, the carbonic acid converts to a solution of alkaline carbonate salts. This water eventually flows into the ocean and increases its alkalinity. An alkaline ocean can hold dissolved carbon, while an acidic one will release the carbon back into the atmosphere. The more weathering, the more carbon is transferred to the ocean where some of it eventually becomes part of the sea bottom sediments......... Posted by: Kevin      Read more         Source

October 31, 2007, 8:07 PM CT

Scientists discover new way to make water

In a familiar high-school chemistry demonstration, an instructor first uses electricity to split liquid water into its constituent gases, hydrogen and oxygen. Then, by combining the two gases and igniting them with a spark, the instructor changes the gases back into water with a loud pop.

Researchers at the University of Illinois have discovered a new way to make water, and without the pop. Not only can they make water from unlikely starting materials, such as alcohols, their work could also lead to better catalysts and less expensive fuel cells.

We observed that unconventional metal hydrides can be used for a chemical process called oxygen reduction, which is an essential part of the process of making water, said Zachariah Heiden, a doctoral student and lead author of a paper accepted for publication in the Journal of the American Chemical Society, and posted on its Web site.

A water molecule (formally known as dihydrogen monoxide) is composed of two hydrogen atoms and one oxygen atom. But you cant simply take two hydrogen atoms and stick them onto an oxygen atom. The actual reaction to make water is a bit more complicated: 2H2 + O2 = 2H2O + Energy.

In English, the equation says: To produce two molecules of water (H2O), two molecules of diatomic hydrogen (H2) must be combined with one molecule of diatomic oxygen (O2). Energy will be released in the process......... Posted by: Sarah      Read more         Source

October 30, 2007, 9:53 PM CT

Going Live With Click Chemistry

Click chemistry, one of the most exciting and proficient new techniques for labeling biomolecules in vitro, has now been extended to studies in the context of live cells as well. This breakthrough opens the door for applications to live cell imaging of numerous biomolecules, including glycans, proteins and lipids. The new version of click chemistry was developed by scientists with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) at Berkeley.

"We've developed a copper-free variant of the click chemistry reaction that possesses comparable kinetics to the copper-catalyzed reaction and proceeds within minutes on live cells with no apparent toxicity," said chemist Carolyn Bertozzi, the principal investigator on this project. "This is the first example of a click chemistry reaction that, like the copper-catalyzed version, proceeds at physiologically acceptable temperatures only without the toxic presence of copper".

Bertozzi is the director of Berkeley Lab's Molecular Foundry, a faculty scientist with Berkeley Lab's Materials Sciences and Physical Biosciences Divisions, the T.Z. and Irmgard Chu Distinguished Professor of Chemistry, and a professor of Molecular and Cell Biology at UC Berkeley. She is also an investigator with the Howard Hughes Medical Institute (HHMI), and a leading authority on glycobiology......... Posted by: Sarah      Read more         Source