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Unconventional photoconduction in an atomically thin semiconductor

October 7, 2014 3:36 pm | by David L. Chandler, MIT | News | Comments

It’s a well-known phenomenon in electronics: Shining light on a semiconductor, such as the silicon used in computer chips and solar cells, will make it more conductive. But now researchers have discovered that in a special semiconductor, light can have the opposite effect, making the material less conductive instead. This new mechanism of photoconduction could lead to next-generation excitonic devices.

Researchers demonstrate how direct fluid flow influences neuron growth

October 7, 2014 2:11 pm | News | Comments

Axons are the shafts of neurons, on the tips of which connections are made with other neurons or cells. In a new study in Texas, researchers were able to use microfluidic stimulations to change the path of an axon at an angle of up to 90 degrees. The publication adds insight to the long accepted idea that chemical cues are primarily responsible for axonal pathfinding during human development and nervous system regeneration.

Charge transport jamming in solar cells

October 7, 2014 2:08 pm | News | Comments

Conventional silicon solar cells could have an inexpensive competitor in the near future. Researchers in Europe have examined the working principle of a cell where an organic-inorganic perovskite compound acts as a light absorber. The scientists observed that charge carriers accumulate in a layer in these photovoltaic elements. If this jam can be dissolved, the already considerable efficiency of these solar cells could be further improved.

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Droplets made to order

October 7, 2014 9:33 am | by David L. Chandler, MIT | News | Comments

Massachusetts Institute of Technology researchers have developed a new way of creating surfaces on which droplets of any desired shape can spontaneously form. They say this approach could lead to new biomedical assay devices and light-emitting diode display screens, among other applications. The new work represents the first time that scientists can control the shape of the contact area of the droplets.

A quick look at electron-boson coupling

October 7, 2014 8:56 am | by Lynn Yarris, Lawrence Berkeley National Laboratory | News | Comments

Imagine being able to tune the properties of a solid material just by flashing pulses of light on it. That is one potential payoff of electrons and atoms interacting with ultrashort pulses of light. The technology of ultrafast spectroscopy is a key to understanding this phenomenon and now a new wrinkle to that technology, observations of electron self-energy, has been introduced by Lawrence Berkeley National Laboratory researchers.

New method creates scrolling nanosheets on demand

October 6, 2014 2:37 pm | by Poncie Rutsch, Okinawa Institute of Science and Technology | News | Comments

Nanoparticles could revolutionize the medical industry, but they must first target a specific region in the body, be trackable, and perform their function at the right moment. Researchers in Japan have made progress in this direction with a new type of nanomaterial: the nanosheet. Specifically, they have designed a strong, stable and optically traceable smart 2-D material that responds to pH, or the acidity or basicity of its environment.

Nanoparticles break the symmetry of light

October 6, 2014 12:59 pm | News | Comments

At the Vienna Univ. of Technology gold nanoparticles have been coupled to a glass fiber. The particles emit light into the fiber in such a way that it does not travel in both directions, as one would expect. Instead, the light can be directed either to the left or to the right. This became possible by employing the spin-orbit coupling of light, creating a new kind of optical switch that has the potential to revolutionize nanophotonics.

Fast, cheap nanomanufacturing

October 6, 2014 9:19 am | by Larry Hardesty, MIT | News | Comments

Arrays of tiny conical tips that eject ionized materials are being made at the Massachusetts Institute of Technology. The technology, which harnesses electrostatic forces, has a range of promising applications, such as spinning out nanofibers for use in “smart” textiles or propulsion systems for fist-sized “nanosatellites.” The latest prototype array that generates 10 times the ion current per emitter that previous arrays did.

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Online resource provides free tools, simulations for composite materials

October 3, 2014 11:59 am | News | Comments

Individuals in industrial associations, educational institutions and government organizations who are interested in composites, or materials made from constituent materials with different physical or chemical properties, now have free, 24/7 access to simulation tools through an online community with offices in the Purdue Research Park.

Study: Surfactants do not harm the environment

October 3, 2014 11:03 am | by Janne Hansen, Aarhus Univ. | News | Comments

You can brush your teeth, and wash yourself and your clothes with a clear conscience. The most common soaps, shampoos and detergents actually pose a minimal risk to the environment. This is the conclusion of a comprehensive survey that covers more than 250 scientific studies over several decades.

Batteries included: A solar cell that stores its own power

October 3, 2014 9:07 am | by Pam Frost Gorder, Ohio State Univ. | News | Comments

The world’s first “solar battery”, invented by researchers at Ohio State Univ., is a battery and a solar cell combined into one hybrid device. Key to the innovation is a mesh solar panel, which allows air to enter the battery, and a special process for transferring electrons between the solar panel and the battery electrode. Inside the device, light and oxygen enable different parts of the chemical reactions that charge the battery.

Creating nanostructures using simple stamps

October 2, 2014 1:31 pm | News | Comments

Nanostructures of virtually any possible shape can now be made using a combination of techniques developed to exploit the unique properties of so-called perovskites. The group based in the Netherlands, developed a pulsed laser deposition technique to create patterns in ultra thin layers, one atomic layer at a time. The perovskites’ crystal structure is undamaged by this soft lithography technique, maintaining electrical conductivity.

Stressed out: Research sheds new light on why rechargeable batteries fail

October 2, 2014 8:18 am | by Marcia Goodrich, Michigan Technological Univ. | News | Comments

Drawn relentlessly by their electrical charges, lithium ions in a battery surge from anode to cathode and back again. Yet, no one really understands what goes on at the atomic scale as lithium ion batteries are used and recharged. Using transmission electron microscopy, researchers are now glimpsing what can happen to anodes as lithium ions work their way into them. The “atomic shuffling” these ions perform leads to rapid anode failure.

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Study: Nanoparticles accumulate quickly in wetland sediment

October 2, 2014 8:14 am | by Ken Kingery, Duke Univ. | News | Comments

A Duke Univ. team has found that nanoparticles called single-walled carbon nanotubes accumulate quickly in the bottom sediments of an experimental wetland setting, an action they say could indirectly damage the aquatic food chain. According to the research, the risk to humans ingesting the particles through drinking water is slight, but aquatic food chains might be harmed by molecules "piggybacking" on the carbon nanoparticles.

“Stealth” nanoparticles could improve cancer vaccines

October 2, 2014 8:01 am | News | Comments

Cancer vaccines have recently emerged as a promising approach for killing tumor cells before they spread. But so far, most clinical candidates haven’t worked that well. Now, scientists have developed a new way to deliver vaccines that successfully stifled tumor growth when tested in laboratory mice. And the key is in the vaccine’s unique stealthy nanoparticles.

Unexpected new mechanism reveals how molecules become trapped in ice

October 1, 2014 11:34 am | News | Comments

Ice contains many atoms and molecules trapped inside its structure. A team of Univ. of Chicago and Loyola Univ. researchers has discovered a new mechanism they call "stable energetic embedding" of atoms and molecules within ice. This mechanism explains how some molecules, such as CF4, or "carbon tetrafluoride", interact with and become embedded beneath ice surfaces.

New method helps portable detection of potent “bath salts” drugs

October 1, 2014 11:25 am | News | Comments

Despite being outlawed in 2012 in the U.S., the synthetic drugs known as "bath salts" are still readily available in some retail shops, on the Internet and on the streets. To help law enforcement, scientists are developing low-cost, disposable, mercury-free electrodes that could be the basis for the first portable, on-site testing device for identifying the drugs.

All directions are not created equal for nanoscale heat sources

October 1, 2014 10:11 am | News | Comments

Thermal considerations are rapidly becoming one of the most serious design constraints in microelectronics, especially on submicron scale lengths. A study by researchers from the Univ. of Illinois at Urbana-Champaign has shown that standard thermal models will lead to the wrong answer in a 3-D heat-transfer problem if the dimensions of the heating element are on the order of one micron or smaller.

“Smart” bandage emits phosphorescent glow for healing below

October 1, 2014 9:37 am | News | Comments

Inspired by a desire to help wounded soldiers, an international team has created a paint-on, see-through, “smart” bandage that glows to indicate a wound’s tissue oxygenation concentration. Because oxygen plays a critical role in healing, mapping these levels in severe wounds and burns can help to greatly improve the success of surgeries to restore limbs and physical functions.

Ultrafast remote switching of light emission

October 1, 2014 9:15 am | News | Comments

Researchers in the Netherlands can now, for the first time, remotely control a miniature light source at timescales of 200 trillionths of a second. Physicists have developed a way of remotely controlling the nanoscale light sources at an extremely short timescale. These light sources are needed to be able to transmit quantum information.

Platinum meets its match in quantum dots from coal

October 1, 2014 8:31 am | by Mike Williams, Rice Univ. | News | Comments

Graphene quantum dots created at Rice Univ. grab onto graphene platelets like barnacles attach themselves to the hull of a boat. But these dots enhance the properties of the mothership, making them better than platinum catalysts for certain reactions within fuel cells.

A new dimension for integrated circuits: 3-D nanomagnetic logic

September 30, 2014 1:39 pm | News | Comments

Electrical engineers in Germany have demonstrated a new kind of building block for digital integrated circuits. Their experiments show that future computer chips could be based on 3-D arrangements of nanometer-scale magnets instead of transistors. In a 3-D stack of nanomagnets, the researchers have implemented a so-called “majority” logic gate, which could serve as a programmable switch in a digital circuit.

Cheap hydrogen fuel from the sun, without rare metals

September 30, 2014 1:27 pm | by Emmanuel Barraud, EPFL | Videos | Comments

Michael Grätzel’s laboratory in Switzerland is producing hydrogen fuel from sunlight and water. By combining a pair of solar cells made with a mineral called perovskite and low cost electrodes, scientists have obtained a 12.3% conversion efficiency from solar energy to hydrogen, a record using earth-abundant materials as opposed to rare metals.

Adding natural uncertainty improves mathematical models

September 30, 2014 1:11 pm | News | Comments

Mathematicians from Brown Univ. have introduced a new element of uncertainty into an equation used to describe the behavior of fluid flows. Ironically, allowing uncertainty into a mathematical equation that models fluid flows makes the equation much more capable of correctly reflecting the natural world, including the formation, strength, and position of air masses and fronts in the atmosphere.

Researchers develop transparent nanoscintillators for radiation detection

September 30, 2014 7:56 am | by Traci Peterson, Univ. of Texas at Arlington | News | Comments

A Univ. of Texas at Arlington research team says recently identified radiation detection properties of a light-emitting nanostructure built in their lab could open doors for homeland security and medical advances. In a paper to be published in Optics Letters, the team describes a new method to fabricate transparent nanoscintillators by heating nanoparticles composed of lanthanum, yttrium and oxygen until a transparent ceramic is formed.

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