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Showing Spotlights 961 - 968 of 2140 in category (newest first):


Quantum point contact microscopy - a novel method for surface characterization

quantum_point_contact_microscopyThe atomic structures of nanoscale contacts are not available in most experiments on quantum transport. Scanning tunneling microscopy operates at a tip-sample distance of a few angstroms and relies on probing a conductive surface in the evanescent tail of electronic states. By decreasing the tip-sample distance the sensitivity to chemical interactions can be enhanced. This has already been demonstrated in non-contact atomic force microscopy, where the oscillating tip comes for short periods of time within the range of chemical interactions. A team of scientists has now developed Quantum Point Contact Microscopy as a novel imaging mode of low-temperature STM, where instead of measuring a current through a tunneling junction, a transport current through a quantum point contact formed by a single atom between the STM tip and the surface is recorded.

Posted: Aug 16th, 2011

Listening in on extracellular communications with a nanoplasmonic resonator

nanoplasmonic_resonatorExtracellular signaling molecules are the language that cells use to communicate with each other. These molecules transfer information not only via their chemical compositions but also through the way they are distributed in space and time throughout the cellular environment. With the development of nanosensing techniques, scientists are trying to to eavesdrop on the cellular whisper and they getting closer to deciphering extracellular signaling - an important task in understanding how cells organize themselves, for instance during organ development or immune responses. Now, researchers have reported a novel sensing technique to interrogate extracellular signaling at the subcellular level. They developed a nanoplasmonic resonator array to enhance fluorescent immunoassay signals up to more than one hundred times to enable the first time submicrometer resolution quantitative mapping of endogenous cytokine secretion from an individual cell in nanoscale close to the cell.

Posted: Aug 15th, 2011

Connecting the dots - fused metal shapes on DNA origami

nanostructures_on_DNADNA origami is a design technique that is used by nanotechnology researchers to fold DNA strands into something resembling a programmable pegboard on which different nanocomponents can be attached. These DNA assemblies allow the bottom-up fabrication of complex nanostructures with arbitrary shapes and patterns on a 100 nm scale. For instance, DNA origami have been heralded as a potential breakthrough for the creation of nanoscale circuits and devices. DNA can also be metallized with different metals, resulting in conducting nanowires. Researchers have now have developed a method to assemble metallic nanocircuits with arbitrary shapes, by attaching metallic nanoparticles to select locations of the DNA origami and then fusing them to form wires, rings, or any other complex shape. These pre-designed structures are programmed by fully utilizing the self-assembling and recognition properties of DNA.

Posted: Aug 11th, 2011

Superhydrophobic tracks for drop transport open path to low-cost microfluidics

microfluidicsResearchers in Finland and Israel have explored the feasibility of using superhydrophobicity for guided transport of water droplets in microfluidic devices. They demonstrate a new, simple and general approach for transportation of water droplets based on superhydrophobic technology. Water droplets are transported at high velocity in almost totally water-repellent tracks with vertical walls. Drops move in open tracks, machined in metal or silicon wafers, using gravity or using electrostatic charge. Usually, in digital microfluidics, droplets are formed in a system of two immiscible liquids, for example, water in oil, and the liquid volume is transported in microchannels using pumps and valves. In this new approach droplets in air can be used. Employing superhydrophobic tracks, droplets can be transported with low friction and high efficiency.

Posted: Aug 9th, 2011

Designer molecules open new manufacturing route for materials scientists

nanocompositeSuper-tough materials with exceptional mechanical properties are in critical need for applications under extreme conditions such as jet engines, power turbines, catalytic heat exchangers, military armors, airplanes, and spacecraft. Researchers involved in improving man-made composite materials are trying to understand how some of the amazing high-performance materials found in nature can be copied or even improved upon. Nature has evolved complex bottom-up methods for fabricating ordered nanostructured materials that often have extraordinary mechanical strength and toughness. The main problem in making nanocomposite materials is how the separate components can be interfaced without losing the good properties of each component. Researchers were now able to show that biomolecules that may seem soft and fragile can actually strengthen a composite material by creating cohesion between two materials that differ much from each other.

Posted: Aug 8th, 2011

Personal nanoparticle respiratory deposition sampler streamlines exposure assessment

nanoparticle_respiratory_samplerUntil more information becomes available on the mechanisms underlying nanomaterial toxicity, it is uncertain what measurement technique should be used to monitor exposures in the workplace. Many of the sampling techniques that are available for measuring airborne nano aerosols vary in complexity but can provide useful information for evaluating occupational exposures with respect to particle size, mass, surface area, number concentration, and composition. Unfortunately, relatively few of these techniques are readily applicable to routine exposure monitoring. That's why researchers have now developed a unique new sampler design that collects nanoparticles separately from larger particles in a way that mimics the respiratory system.

Posted: Aug 4th, 2011

New cloaking material hides objects otherwise visible to the human eye

Exotic artificial composite materials called metamaterials can be engineered with certain electromagnetic properties that allows them to act as invisibility cloaks. These materials bend all light or other electromagnetic waves around an object hidden inside a metamaterial cloak, to emerge on the other side as if they had passed through an empty volume of space. Researchers have already been experimenting with cloaking devices for various, usually longer wavelengths such as microwave or infrared waves. Recently, even graphene has been added to the family of cloaking materials. Now, for the first time, a team of scientists at UC Berkeley have devised an invisibility cloak material that hides objects from detection using light that is visible to humans.

Posted: Aug 3rd, 2011

Photonic crystal tablets - the future of iPads?

photonic-crystal_tabletStructural color - where the color results from interferences, not pigments - is a natural fit for new display technologies and writing substrates since it can provide vivid colors in environments of high intensity light (e.g. sunlight) without the need for additional illuminating power. Most existing display technologies such as LCDs and LEDs require power to actively project colors and often suffer from performance degradations in these reflective environments. Recognizing this, researchers have developed a number of techniques for dynamically and spatially modulating the colors reflected off of photonic crystal-like substrates. In new work, researchers have demonstrated an electrical-power-free infusion technique that allows them to draw multi-color images on colloidal photonic crystal substrates using transparent imaging oils.

Posted: Aug 2nd, 2011