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March 9, 2008, 4:59 PM CT

Skewered Pumpkins

Skewered Pumpkins
We encounter valves every day, whether in the water faucet, the carburetor in our car, or our bicycle tire tube. Valves are also present in the world of nanotechnology. A team of scientists headed by J. Fraser Stoddart and Jeffrey I. Zink at the University of California, Los Angeles, has now developed a new nanovalve. In the journal Angewandte Chemie, the researchers reveal what is special about it: In contrast to previous versions, which only function in organic solvents, this valve operates in an aqueous environment and under physiological conditions-prerequisites for any application as a gate for nanoscopic drug-transport agents, which need to set their cargo free at the right place and time.

In order for pharmaceuticals to affect only the target diseased organ, suitable nanopackaging is mandatory to bring the drug to the target area and release it only there. One example of a good nanoscopic packaging agent is a tiny sphere of porous silica. Its pores can be filled with the drug and closed with tiny controllable valves.

The researchers attached stem-shaped molecules onto the surface of the porous spheres and filled the pores with guest molecules. At neutral to acidic pH values, they stacked cucurbituril molecules onto these "stems". Cucurbituril is a fat, ring-shaped molecule reminiscent of a pumpkin that has both ends hollowed out. The resulting supramolecular structure, which resembles a skewered pumpkin and is known to chemists as a pseudorotaxane, blocks the pores, so that the guest molecules cannot exit. The nanovalve is closed.........

Posted by: John      Read more         Source


March 5, 2008, 7:50 PM CT

Containing Carbon Dioxide

Containing Carbon Dioxide
Injecting CO2, the most troublesome greenhouse gas, into porous rock formations beneath the earth might be the best short-term option for slowing global warming. Los Alamos scientists are developing a comprehensive risk assessment program to ensure safe and effective CO2 containment. This program includes a unique computer model, named "CO2-PENS," to guide the choice and development of the best sites; laboratory experiments to understand the geochemistry of sequestration systems; and field studies to quantify natural CO2 flux in the ecosystem. Los Alamos has advanced its geologic sequestration research by partnering with the Enhanced Oil Recovery Industry, which has injected CO2 underground for 30 years.

The average American family of four puts about three tons of garbage per year by the curb, but because we burn fossil fuels for electricity, heat, and transportation, that same family is annually responsible for dumping about 80 tons of carbon dioxide (CO2) into the atmosphere-CO2 that contributes to global climate change.

Some believe we should just stop using fossil fuels, but that won't happen in the near future unless we're willing to cripple our economy and keep the developing world in poverty. Eighty-six percent of the world's energy comes from fossil fuels, and projections show energy demand and fossil fuel use rising dramatically. China, India, and the United States are planning to add 850 new coal-fired power plants to the 2,100 worldwide that currently chug out one-third of the world's human-generated CO2 emissions.........

Posted by: Nora      Read more         Source


Wed, 13 Feb 2008 01:37:38 GMT

Dicranopteris linearis

Dicranopteris linearis
Thank you again to Krystyna Szulecka for sharing another of her excellent photographs (posted in this thread in the BPotD submissions forum). If you like, see more of Krystyna''s images by searching for “Krystyna” on the FLPA web site.

Given its distribution, it''s doubtless that Dicranopteris linearis has dozens of common names. Four names frequently used are Uluhe fern, climbing fern, false staghorn and Old World forked fern. According to GRIN, it can be found in tropical and subtropical areas throughout the Old World. That left me puzzled for a bit, as Plants of Hawaii Volcanoes National Park lists it as indigenous and the USDA PLANTS database displays it as native to Hawaii The mystery was partially resolved when I looked at GRIN''s entry for Dicranopteris linearis f. marginata, noted to be found in Hawaii. So, it appears to be a small oversight that Hawaii isn''t included in the broader distribution list.

The Plants of Hawaii Volcanoes National Park has a photograph clearly illustrating the reason for one of the common names, climbing fern. More photographs, particularly with respect to propagation, are available in the PDF suggested by Krystyna: The Propagation and Production of Uluhe Fern (Dicranopteris linearis) for Potential Use as a Restoration Species (a presentation given to the International Plant Propagators'' Society).

The New South Wales Flora Online provides a small scientific description of the species.

Posted by: Daniel Mosquin      Read more     Source


January 29, 2008, 9:45 PM CT

Magnetism loses under pressure

Magnetism loses under pressure
Magnetite is an abundant magnetic mineral. It was used by early navigators to find the magnetic North Pole and birds use if for their navigation.There is intense scientific interest in its properties.

Credit: Image courtesy © 2000 John H. Betts
Washington, D.C. Scientists have discovered that the magnetic strength of magnetitethe most abundant magnetic mineral on Earthdeclines drastically when put under pressure. Researchers from the Carnegie Institutions Geophysical Laboratory, together with colleagues at the Advanced Photon Source of Argonne National Laboratory, have found that when magnetite is subjected to pressures between 120,000 and 160,000 times atmospheric pressure its magnetic strength declines by half. They discovered that the change is due to what is called electron spin pairing.

Magnetism comes from unpaired electrons in magnetic materials. The strength of a magnet is a result of the spin of unpaired electrons and how the spins of different electrons are aligned with one another. This research showed that the drop in magnetism was due to a decrease in the number of unpaired electrons.

Magnetite is found in small quantities in certain bacteria, in brains of some birds and insects, and even in humans, commented Yang Ding, the studys lead author with the Carnegie-led High-Pressure Synergetic Consortium. Early navigators used it to find the magnetic North Pole and birds use it for their navigation. And now it is used in nanotechnology. There is intense scientific interest in its properties. Understanding the behavior of magnetite is difficult because the strong interaction among its electrons complicates its electronic structure and magnetic properties.........

Posted by: Nora      Read more         Source


December 20, 2007, 9:36 PM CT

Proton Camera

Proton Camera
Lab researchers, working with Teledyne Imaging Sensors, have built the world's fastest camera, and it has just won an R&D 100 Award from R&D Magazine as one of the 100 most technologically significant products of 2007.

Made from two bonded microelectronic chips, the "Camera on a Chip" can capture 2.8 million frames per second. A normal motion picture camera captures 24 frames per second.

The camera produces movies of ultra-short (sub-microsecond) processes, mostly induced by powerful high explosives. These processes are studied using a remarkable imaging technique known as proton radiography, in which high-energy protons pass through an explosives-driven object to a screen, where they produce a blue "shadowgraph," essentially a two-dimensional representation of the object.

The camera takes pictures of the shadowgraphs in as little as 50 billionths of a second per frame, freezing images of the object's high-speed motions and storing up to three of them "on-chip" at one time. Several cameras can be used together to make a movie of tens of frames or more.

With very high sensitivity in both the visible and near-visible frequencies, the camera can also be used for a number of other applications, including studies of internal-combustion engines, vehicle-impact tests, and armor-penetration experiments; laser-beam identification of minerals on Mars; and location of fast-moving targets in space.........

Posted by: John      Read more         Source


December 12, 2007, 10:04 PM CT

Nanoscale Details of Photolithography Process

Nanoscale Details of Photolithography Process
Schematic of the photolithography process shows the formation of a gradient extending from the photoresist material to be removed (center) into the unexposed portions of the resist on the sides. NIST measurements document the residual swelling fraction caused by the developer that can contribute to roughness in the final developed image.
Researchers at the National Institute of Standards and Technology (NIST) have made the first direct measurements of the infinitesimal expansion and collapse of thin polymer films used in the manufacture of advanced semiconductor devices. It's a matter of only a couple of nanometers, but it can be enough to affect the performance of next-generation chip manufacturing. The NIST measurements, detailed in a new paper,* offer a new insight into the complex chemistry that enables the mass production of powerful new integrated circuits.

The smallest critical features in memory or processor chips include transistor "gates." In today's most advanced chips, gate length is about 45 nanometers, and the industry is aiming for 32-nanometer gates. To build the nearly one billion transistors in modern microprocessors, manufacturers use photolithography, the high-tech, nanoscale version of printing technology. The semiconductor wafer is coated with a thin film of photoresist, a polymer-based formulation, and exposed with a desired pattern using masks and short wavelength light (193 nm). The light changes the solubility of the exposed portions of the resist, and a developer fluid is used to wash the resist away, leaving the pattern which is used for further processing.

Exactly what happens at the interface between the exposed and unexposed photoresist has become an important issue for the design of 32-nanometer processes. Most of the exposed areas of the photoresist swell slightly and dissolve away when washed with the developer. However this swelling can induce the polymer formulation to separate (like oil and water) and alter the unexposed portions of the resist at the edges of the pattern, roughening the edge. For a 32-nanometer feature, manufacturers want to hold this roughness to at most about two or three nanometers.........

Posted by: John      Read more         Source


Thu, 13 Dec 2007 03:14:46 GMT

Ricinus communis cultivar

Ricinus communis cultivar
Anne from Alberta (aka annkelliott@Flickr) shares another of her great images with BPotD (original | BPotD Flickr Group Pool). Thank you, Anne!

As a child, I thought castor oil was an extract from animals (beavers, specifically). I suppose I can blame that on childhood logic after learning the French name for beaver. It was only much later when I learned that it was a plant derivative from the species in today''s photograph, Ricinus communis, or the castor bean plant. Wikipedia provides a detailed summary of the chemistry and uses of castor oil. In particular, the use as an instrument of intimidation is both interesting and disgusting.

Despite the many uses of castor oil, Ricinus communis also happens to contain a deadly poison, ricin. The entire plant is poisonous if ingested, but the seeds are particularly potent; one chewed seed may be enough to kill a child, see: ricin toxin. The Cornell web site also contains a page about the plant itself, Ricinus communis, where it explains that ricin is water-soluble and hence will not find its way into castor oil during the production process provided proper precautionary measures are taken (thanks to Anne for the link, as well).

The widespread tropical and subtropical cultivation of Ricinus communis has made it difficult to determine its original distribution. The Handbook of Energy Crops, in addition to providing extensive details about cultivation and production, suggests Ricinus communis is African in origin. The comprehensive photographs of the species available on MissouriPlants.com are accompanied by a write-up suggesting an Asian origin.

Posted by: Daniel Mosquin      Read more     Source


December 11, 2007, 8:35 PM CT

Software Helps Mars Rovers Find Winter Havens

Software Helps Mars Rovers Find Winter Havens
Ron Li
New software is helping NASA find safe places for the Spirit rover to ride out future Martian winters -- and also plan where Spirit and its companion rover, Opportunity, will explore in the future.

The steep Martian mesa dubbed "Von Braun" would be a safe haven, the software and data analysis determined -- but the path that Spirit would have to follow to get there is a little too risky to travel with winter on the way, explained Ron Li, professor of civil and environmental engineering and geodetic science at Ohio State University.

That's one reason why Spirit is currently headed to the northern rim of a depression called "Home Plate" for the winter -- though, as of early December, it was rolling through loose soil that was hampering its progress.

Li and his research team are in the process of developing several software programs to help the rovers navigate. The latest program used satellite images, as well as rover images, to determine that Von Braun's more than 25-degree incline is steep enough for the rover's solar panels to gather critical energy from the low winter sun. But it also determined that there are no safe winter sites on the route to Von Braun where the rover could hide out in a pinch.

Should Spirit set out on the 400-foot journey to Von Braun and not be able to reach it, there are not enough bail out spots along the route where it could take refuge, the software found. Even in ideal driving conditions, the trip would take many days. And with the winter approaching, Spirit might need to stop at steep slopes where it could better angle its solar panels to gather light.........

Posted by: Edwin      Read more         Source


December 10, 2007, 10:31 PM CT

MIT creates oil-repelling materials

MIT creates oil-repelling materials
MIT engineers have designed a class of material structures that can repel oils, a novel discovery that could have applications in aviation, space travel and hazardous waste cleanup. Such materials could be used to help protect parts of airplanes or rockets that are vulnerable to damage from being soaked in fuel, like rubber gaskets and o-rings.

"These are vulnerable points in a number of aerospace applications," said Robert Cohen, the St. Laurent Professor of Chemical Engineering and an author of a paper on the work that appeared in the Dec. 7 issue of Science.

"It would be nice if you could spill gasoline on a fabric or a gasket or other surface and find that instead of spreading, it just rolled off," Cohen said.

Creating a strongly oil-repelling, or "oleophobic" material, has been challenging for scientists, and there are no natural examples of such a material.

"Nature has developed a lot of methods for waterproofing, but not so much oil-proofing," said Gareth McKinley, MIT School of Engineering Professor of Teaching Innovation in the Department of Mechanical Engineering and a member of the research team. "The conventional wisdom was that it couldn't be done on a large scale without very special lithographic processes".

The tendency of oils and other hydrocarbons to spread out over surfaces is due to their very low surface tension (a measure of the attraction between molecules of the same substance).........

Posted by: John      Read more         Source


Mon, 10 Dec 2007 04:21:34 GMT

Hibiscus clayi

Hibiscus clayi
A thank you to frolickauai@Flickr for today''s first-time contribution to Botany Photo of the Day (original | BPotD Flickr Group Pool). Much appreciated! Do investigate frolickauai''s other photographs on Flickr – plenty of plant photographs.

Hibiscus clayi, or Clay''s hibiscus (or Hawaiian red hibiscus), is an extremely rare plant in the wild; as frolickauai notes: “This flower is on one of only four naturally occurring members of Hibiscus clayi in the wild.”. The wild, in this case, is Kaua‘i, Hawaii. Conservation efforts are underway to expand the population beyond the four individuals, and botanical gardens in the area are part of the effort (ref: US Botanical Garden summary). Despite being in a forest reserve, the remaining individuals remain under threat. The profile of Hibiscus clayi on the US Center for Plant Conservation notes that competition with alien plants is the current major problem, although the initial decline was due in large part to cattle grazing (cattle are no longer a threat, though feral pigs are another issue).

The Plants of Hawaii site contains photographs of Hibiscus clayi in cultivation, as well as a resource page about the species.

Posted by: Daniel Mosquin      Read more     Source


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