July 20, 2006, 10:02 PM CT

Add Nanotubes and Stir

Polymer researchers at the National Institute of Standards and Technology have some stirring results to share with scientists and companies developing new, advanced composite materials with carbon nanotubes-mix carefully.

In a paper for Physical Review Letters,* they explain how the amount of force applied while mixing carbon nanotube suspensions influences the way the tiny cylinders ultimately disperse and orient themselves. In turn, the final arrangement of the nanotubes largely dictates the properties of the resultant materials.

Measuring only a few nanometers in diameter (the width of a handful of atoms), carbon nanotubes possess a number of superior properties that make them highly desirable additives in composites, a class of engineered materials made by blending polymers and fibers or by combining other types of unlike materials. Mixed in polymeric materials, carbon nanotubes can provide incredible strength, toughness and electrical conductivity. The trouble is, nanotubes stick to each other and form networks that tend to stay fixed in place. Apply enough force, the networks will flow but commonly end up in tangled clumps. The resultant nanocomposites are difficult to mold or shape, and their properties fall short of expectations.

In an elegantly simple result, NIST scientists Erik Hobbie and Dan Fry observed that networks of carbon nanotubes respond predictably to externally applied force. The networks also showed behavior reminiscent of more conventional materials that align spontaneously under the forces of Brownian motion-the random motion of particles in a fluid famously described mathematically by Einstein.........

Posted by: Kevin      Permalink         Source

July 19, 2006, 9:09 PM CT

Predicting Crystal Structures

The same computer methods used by online sales sites to suggest books to customers can help predict the crystal structures of materials, MIT scientists have found.

These structures are key to designing new materials and improving existing ones, which means that everything from batteries to airplane wings could be influenced by the new method.

The researchers report their findings in the July 9 online edition of Nature Materials.

Using a technique called data mining, the MIT team preloaded the entire body of historical knowledge of crystal structures into a computer algorithm, or program, which they had designed to make correlations among the data based on the underlying rules of physics.

Harnessing this knowledge, the program then delivers a list of possible crystal structures for any mixture of elements whose structure is unknown. The team can then run that list of possibilities through a second algorithm that uses quantum mechanics to calculate precisely which structure is the most stable energetically -- a standard technique in the computer modeling of materials.

"We had at our disposal all of what is known about nature," said Professor Gerbrand Ceder of the Department of Materials Science and Engineering, leader of the research team. Ceder compared the database of crystal structures to the user database of an online bookseller, which can make correlations among millions of customers with similar interests. "If you tell me you've read these 10 books in the last year and you rate them, can I make some prediction about the next book you're going to like?".........

Posted by: Sarah      Permalink         Source

July 17, 2006, 5:01 AM CT

Undersea Vehicles to Study Formation of Gold

An international team of researchers will explore the seafloor near Papua New Guinea in the western Pacific Ocean later this month with remotely operated and autonomous underwater vehicles, investigating active and inactive hydrothermal vents and the formation of mineral deposits containing copper, gold and other commercially valuable minerals.

The cruise is a joint expedition between Woods Hole Oceanographic Institution (WHOI) and Nautilus Minerals Inc. of Vancouver, British Columbia, a mining exploration company that holds exploration leases in the Bismarck Sea within the territorial waters of Papua New Guinea. Nautilus is the first firm to commercially explore the ocean floor for economically viable massive sulfide deposits, and is interested in understanding the size and mineral content of the seafloor massive sulfide systems.

The joint expedition includes a 32-day WHOI research program funded by the U.S. National Science Foundation to the Pacmanus vent sites in the Eastern Manus Basin. The remotely operated vehicle Jason will be used to survey and map the vent areas around an Ocean Drilling Program hole drilled in 2000. Nautilus will fund an additional 10-day program to explore and sample the Vienna Woods sulfide prospects on the Manus Ridge, northwest of the Pacmanus study area.........

Posted by: Tyler      Permalink         Source

July 13, 2006, 7:03 AM CT

Ligands, The Ties That Bind

A number of transition metals react with bases (such as ammonia) to produce beautifully colored transition metal-ligand complexes. The word ligand comes from the Latin ligare which means to tie or bind. The same root leads to ligaments, which tie your bones together.

The photo shows green Ni(H2O)62+ and blue green Ni(NH3)62+. The ligands are water and ammonia respectively, "tied" to the Ni(II) center. The ligands form an octahedron around the metal center.........

Posted by: Sarah      Permalink         Source

July 11, 2006, 11:43 PM CT

Chemists To Produce Faster Computers

Experts have been working for a number of years to understand how to work with electronic material produced on an increasingly small scale. In the emerging field of nano-science and nano-technologies it is important for researchers to be able to control the structure and bonding of molecules that are used in creating small scale electronic components for products such as computers.

Researchers at Liverpool have succeeded in imaging and forming a unique bond between a single gold atom and a single organic molecule called a pentacene. They managed to bind the atom to the pentacene and take images of rearrangements of the electrons participating in the formation of the chemical bond.

The team selected the pentacene as it is a special class of molecule that has qualities of particular use in molecular electronics. The gold atom is a metal atom that attracts an extra electron.

Professor Mats Persson, from the University's Department of Chemistry said: "This new experiment allows us to control the arrangement and shape of chemical bonds and to gain new insight into making contact with a single molecule with potential importance for molecular electronics. There will come a time when electronic material will become so small that we will need to control the structure down to the atomic scale and the chemical bonds between single molecules and atoms.........

Posted by: Sarah      Permalink         Source

July 11, 2006, 6:22 PM CT

Creation Of New Gel Nanomaterial

In an ever-expanding world of nano-technology researchers have created organic gel nano-materials. This newly created nano-meterial could be used to encapsulate pharmaceutical, food, and cosmetic products and to build 3-D biological scaffolds for tissue engineering. Researchers used olive oil and six other liquid solvents, the scientists added a simple enzyme to chemically activate a sugar that changed the liquids to createorganic gels.

"We are using the building blocks provided by nature to create new nanomaterials that are completely reversible and environmentally benign," said Rensselaer's Jonathan Dordick, leader of the research team. "The importance of this finding is the ability to use the same naturally occurring enzyme both to create chemically functional organogels and to reverse the process and break down these gels into their biologically compatible building blocks".

In the experiments, researchers activated a sugar using a simple enzyme, which generated a compound that self-assembles into 3-D fibers measuring approximately 50 nanometers in diameter. As the fibers entangle, a large amount of solvent gets packed together, trapping some 10,000 molecules.

The resulting organogel materials could be used as biocompatible scaffolds for tissue engineering and designing membranes, according to Dordick. Other possible applications include delivery systems for pharmaceuticals and preservatives for food and cosmetics.........

Posted by: Sarah      Permalink

June 26, 2006, 7:58 PM CT

New Method For Water-purification

Researchers from Delft University of Technology have discovered a new method that could drastically change the way we purify water within a few years. This new technology was developed by Delft, in partnership with DHV engineering bureau. This represents a compact and environmentally-friendly purification method, in which aerobic bacteria form granules that sink quickly. An important part of the project's success was the work of Delft researcher Merle de Kreuk, who, is about to receive her PhD degree based on this research subject.

With the new aerobic granular sludge technology (Nereda TM), aerobic (thus oxygen using) bacterial granules are formed in the water that is to be purified. The great advantage of these granules is that they sink quickly and that all the mandatory biological purifying processes occur within these granules.

The technology therefore offers important advantages when compared to conventional water purification processes. For example, all the processes can occur in one reactor. Moreover, there is no need to use large re-sinking tanks, such as those used for conventional purification. Such large tanks are needed for this because the bacteria clusters that are formed take much longer to sink than the aerobic granule sludge.

As per Delft PhD researcher Merle de Kreuk, a Nereda TM purification installation needs only a quarter of the space mandatory by conventional installations. Moreover, Nereda TM uses 30% less energy than the normal purification process. This Nereda TM purification process is suitable for both domestic and industrial waste water.........

Posted by: Kevin      Permalink         Source

June 24, 2006, 11:59 PM CT

Diamond As A By-Product

There may not be a pot of gold at the end of the rainbow, but there appears to be nanocrystalline diamonds at the end of a process to produce and store hydrogen using anthracite coal.

"The idea we explored was based on ball milling graphite processes found in the hydrogen storage literature," said Angela D. Lueking, assistant professor of energy and geoenvironmental engineering. "We substituted anthracite coal for graphite because it is abundant and inexpensive. Now, with 20/20 hindsight, we are struck by the fact that coal gasification is currently the most economical way to produce hydrogen."

Interest in hydrogen as a vehicular fuel has a number of scientists investigating ways to create hydrogen inexpensively; other scientists are looking at ways to transport and store hydrogen in a safe manner. Lueking's group was exploring a way to store hydrogen in carbon-based materials, and inadvertently stumbled upon a method that combines production and storage and produces nanocrystalline diamonds as a by-product.

Lueking and his colleagues, who included Humberto R. Gutierrez, post doctoral fellow in physics; Dania A Fonseca, post doctoral fellow in the Penn State Energy Institute; Deepa L. Narayanan, Dirk Van Essendelft and Puja Jain, graduate students in energy and geoenvironmental engineering and Caroline E. B. Clifford, research associate, Energy Institute, ball milled powdered anthracite coal with cyclohexene. Ball milling involves mixing a slurry of anthracite powder and cyclohexene with small steel balls and mixing so that the steel balls pound the coal particles and the cyclohexene causing physical and chemical changes. The scientists reported their results in a recent online issue of the Journal of the American Chemical Society.........

Posted by: Kevin      Permalink         Source

June 22, 2006, 9:44 PM CT

When Gold Becomes A Catalyst

Gold has always been perceived as a precious material: you win a gold medal when you prove to be the best in a competition; you only get a Gold credit card when you are a preferential customer, and the jewelry made of this material is amongst the most valuable. However, gold has also unexpected properties: It can act as a catalyst and transform carbon monoxide (CO) to carbon dioxide (CO2) when it comes in the form of tiny pieces, called nano-particles. Gold suddenly enhances desired chemical reactions as a catalyst for example in the removal of odours and toxins or to clean automotive exhaust gases. Scientists from Switzerland, UK, the USA and the ESRF (Grenoble) have monitored the catalytic process and proposed an explanation for the high catalytic activity of gold. They publish today their results in the journal Angewandte Chemie online.

The team used nano-particles of gold instead of bulk gold. The catalyst structure looks as if someone had pulverized a piece of gold and spread the tiny nano-sized pieces over an aluminum oxide support. The properties of the nano-particles are very different from those of bulk gold. Only when the gold atoms are confined to the size of just a few millionth of a millimetre they start showing the desired catalytic behaviour.

Researchers already knew that gold nano-particles react with this kind of setup and catalyses CO with oxygen (O2) into CO2. What they did not know was how the oxygen is activated on the catalyst. In order to find that out, they set up a cell where they could carry out the reaction, and in situ perform an X-ray experiment with the ESRF beam.........

Posted by: Sarah      Permalink         Source

June 18, 2006, 6:17 PM CT

MRI For Fuel Cells

As gasoline prices top $3 a gallon in major cities, the drive toward increasing energy efficiency and reducing air pollution has accelerated, and the development of fuel cells has become a major focus worldwide.

Knowing how fuel cells work is key to improving their performance and reducing the cost of their production. Now a research team led by Scott A. Barnett, professor of materials science and engineering at Northwestern University, has produced the first three-dimensional images of the interior of a fuel cell -- providing a new tool for the study and development of fuel cells.

The researchers' three-dimensional reconstruction of a solid oxide fuel cell anode was reported in a paper published this month by the journal Nature Materials. (A solid oxide fuel cell efficiently converts fuels such as hydrogen and natural gas directly into electricity; Barnett's group also recently reported a similar fuel cell that works with a liquid transportation fuel -- iso-octane, a high-purity compound similar to gasoline.)

"Much like magnetic resonance imaging produces a view inside the human body, we now can look inside fuel cells," said Barnett. "The dual-beam focused-ion-beam microscope used in the study provides much higher resolution than an MRI, showing nanometer-scale features. These pictures will help us and other scientists to unravel how fuel cells work so they can eventually be improved and made to work longer without failing.".........

Posted by: Kevin      Permalink         Source

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