Archive for April 2008
Switchable nanovalves pH-sensitive pseudorotaxane as reversible gate for drug nanotransporter
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 nanotechno. A team of researchers 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 scientists reveal what is special about it: In contrast to prior 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 required 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 scientists 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.
If the pH value is raised into the basic range, however, the interaction between the “pumpkins” and the “skewers” is weakened, and the pumpkins come off, opening the pores. Now the valves are open and the guest molecules can exit.
Engineers make first ‘active matrix’ display using nanowires
WEST LAFAYETTE, Ind. -
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Engineers have created the first “active matrix” display using a new class of transparent transistors and circuits, a step toward realizing applications such as e-paper, flexible color monitors and “heads-up” displays in car windshields.
The transistors are made of “nanowires,” tiny cylindrical structures that are assembled on glass or thin films of flexible plastic. The researchers used nanowires as small as 20 nanometers - a thousand times thinner than a human hair - to create a display containing organic light emitting diodes, or OLEDS. The OLEDS are devices that rival the brightness of conventional pixels in flat-panel television sets, computer monitors and displays in consumer electronics.
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Tiny buckyballs squeeze hydrogen like giant Jupiter
Carbon cages can hold super-dense volumes of nearly metallic hydrogen. Hydrogen could be a clean, abundant energy source, but it’s difficult to store in bulk.
In new research, materials scientists at Rice University have made the surprising discovery that tiny carbon capsules called buckyballs are so strong they can hold volumes of hydrogen nearly as dense as those at the center of Jupiter.
The research appears on the March 2008 cover of the American Chemical Society’s journal Nano Letters.
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The Serial Revolution: Establishing Global Access to Serial Ports
In the process of updating a variety of computer systems and hardware configurations, the plant manager of a Midwest manufacturer needed a centralized network that would connect three buildings within three quarters of a mile, plus a couple more several miles away.
The integration of legacy serial equipment into modern Industrial Networks presents some unique challenges; among these are reliability, connectivity, and limited range. These issues can be easily resolved.
With a wide array of legacy equipment, primarily utilizing serial connections, the need presented a rather complex challenge, especially since serial connections are limited in terms of distance and networking.
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Flying Wing Surpasses Altitude Records for Non-Rocket Airplane
NASA’s solar-powered Helios experimental aircraft lifted off from a U.S. Navy base on the Hawaiian island of Kauai on Monday, reaching a height of 96,500 feet.
The $15 million aircraft failed in its attempt to reach an altitude of 100,000 feet, but it broke a record set by its predecessor, the Pathfinder Plus, for 80,201 feet for solar-powered and propeller-driven aircraft in 1998.
Officials decided to bring down the radio-controlled Helios at 4:08 p.m. Hawaii time (10:08 p.m. EDT), NASA spokesman Alan Brown told the Associated Press, as the craft had reached a “zero climb rate” in thinning air and slanting sunlight.
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