Electrons flowing swiftly across the surface of topological insulators are "spin polarized," their spin and momentum locked. This new way to control electron distribution in spintronic devices makes TIs a hot topic in materials science. Now scientists have discovered more surprises: contrary to assumptions, the spin polarization of photoemitted electrons from a topological insulator is wholly determined in three dimensions by the polarization of the incident light beam.
Researchers from North Carolina State University have developed a new technique for creating stronger, lightweight magnesium alloys that have potential structural applications in the automobile and aerospace industries. To create these magnesium alloys, the researchers introduced nanospaced stacking faults to the alloy using conventional hot rolling technology that is widely used by industry.
Researchers at the University of Illinois at Urbana-Champaign have devised a dynamic and reversible way to assemble nanoscale structures and have used it to encrypt a Morse code message. The team started with a template of DNA origami―multiple strands of DNA woven into a tile. They “wrote” their message in the DNA template by attaching biotin-bound DNA strands to specific locations on the tiles that would light up as dots or dashes.
In a world first, a team of researchers from Australia, China, and the U.S. has created a super strong metallic composite by harnessing the extraordinary mechanical properties of nanowires. According to the study’s authors, the work has effectively overcome a challenge that has frustrated the world's top scientists and engineers for more than three decades, nicknamed the "valley of death" in nanocomposite design.
All living organisms rely on iron as an essential nutrient. In the ocean, iron’s abundance or scarcity means all the difference as it fuels the growth of plankton. A new study from the Woods Hole Oceanographic Institution identifies an unexpectedly large source of iron to the North Atlantic—meltwater from glaciers and ice sheets, which may stimulate plankton growth. This source is likely to increase as melting of the Greenland ice sheet escalates under a warming climate.
A team of researchers from the National University of Singapore (NUS) has successfully altered the properties of water, making it corrosive enough to etch diamonds. This strange result was achieved by attaching a layer of graphene on diamond and heated to high temperatures. Water molecules trapped between them become highly corrosive, as opposed to normal water.
Germany-based company AMSilk has produced the world’s first competitive man-made spider silk fiber, called Biosteel, which is made entirely from recombinant silk proteins. Biosteel has mechanical properties similar to that of natural spider silk when comparing toughness, a measure indicating the kinetic energy absorbed before the fiber breaks.
Until now, atomic force microscopy-based measurements of chemistry and chemical properties of materials were generally not possible. Researchers at the University Illinois report that they have measured the chemical properties of polymer nanostructures as small as 15 nm, using a new technique called atomic force microscope infrared spectroscopy (AFM-IR).
A research group at the University of Toronto has recently described a new technique to improve efficiency in what are called colloidal quantum dot photovoltaics. The method depends on a characteristic of quantum dots: Their light-absorption spectrum can be changed simply by changing the size of quantum dot. By adjusting this property to the infrared portion of the spectrum, efficiency is improved.
Working with microscopic artificial atomic nuclei fabricated on graphene, a collaboration of researchers have imaged the “atomic collapse” states theorized to occur around super-large atomic nuclei. This is the first experimental observation of a quantum mechanical phenomenon that was predicted nearly 70 years ago and holds important implications for the future of graphene-based electronic devices.
While thousands of earthquakes around the globe are recorded by seismometers in these stations—part of the permanent Global Seismographic Network (GSN) and EarthScope's temporary Transportable Array (TA)—signals from large meteor impacts are far less common. The meteor explosion near Chelyabinsk on Feb. 15, 2013, generated ground motions and air pressure waves in the atmosphere. The stations picked up the signals with seismometers and air pressure sensors, and recorded the pressures waves as they cross the United States.
Researchers at the NIST have demonstrated a solid-state refrigerator that uses quantum physics in micro- and nanostructures to cool a much larger object to extremely low temperatures. What's more, the prototype NIST refrigerator, which measures a few inches in outer dimensions, enables researchers to place any suitable object in the cooling zone and later remove and replace it, similar to an all-purpose kitchen refrigerator.
A research group in Japan has recently discovered that it is possible to detect diluted ionic mercury in water with more than 10 times higher sensitivity than with the conventional spectroscopy method. Ionic mercury is a harmful substance when dissolved in rivers and lakes, even in trace amounts. In contrast to the conventional spectroscopic detection method, the infrared spectroscopy detection method was used for this method.
There are currently no engineered systems that operate under conditions similar to those that allow reptiles and amphibians to dart across a water’s surface, or that allow a frog to jump out of the water and catch an insect with a single power stroke. Engineers at Virginia Tech hope to learn more about these living mechanics puzzles so as to develop bio-inspired systems for manufacturing or robotics.
Chemists at the University of South Florida and King Abdullah University of Science and Technology in Saudi Arabia have discovered a more efficient, less expensive and reusable material for carbon dioxide capture and separation. The highly efficient mechanism utilizes a previously underused material—known as SIFSIX-1-Cu—that attracts carbon atoms.
A multi-university research team has used a new spectroscopic method—energy-momentum spectroscopy—to gain a key insight into how light is emitted from layered nanomaterials and other thin films. The technique lets researchers understand the source and orientation of light in light-emitting thin films and could lead to better LEDs, solar cells, and other devices that use layered nanomaterials.
Bringing the concept of an “artificial leaf” closer to reality, a team of researchers at Massachusetts Institute of Technology has published a detailed analysis of all the factors that could limit the efficiency of such a system. The new analysis lays out a roadmap for a research program to improve the efficiency of these systems, and could quickly lead to the production of a practical, inexpensive and commercially viable prototype.
A new analytical theory has been developed at Purdue University that shows how to design experiments to study ways of controlling dendrite growth on electrodes in lithium-ion batteries. Using this approach, the researchers have shown theoretically how to control or eliminate the formation of these dendrites, which cause lithium-ion batteries to fail. The advance could help improve safety and might enable the batteries to be charged within a matter of minutes instead of hours.
Millions of people in Bangladesh and neighboring countries are chronically exposed to arsenic-contaminated groundwater, which causes skin lesions and increases the risk of certain cancers. According to an international team of scientists, human activities are not the primary cause of arsenic found in groundwater in Bangladesh. They found instead that the arsenic is part of a natural process that predates any recent human activity, such as intensive pumping.
The Fischer-Tropsch process is used for producing fuels from synthesis gas, which in turn is made from natural gas, biomass, or coal. Large reserves of shale or natural gas now changing the world energy market have raised interest in this technology, but prior reactors have been too bulky. Inspired by patents from the 1960s audio cassette recording industry, University of Amsterdam chemists have recently developed a new Fischer-Tropsch catalyst that is significantly cheaper and more scalable.
Until recently, there has been no systematic way of evaluating how different anti-fog coatings perform under real-world conditions. A team of MIT researchers has developed such a testing method, and used it to find a coating that outperforms others not only in preventing foggy buildups, but also in maintaining good optical properties without distortion.
Therapeutic and diagnostic in function, so-called “theranostic” particles have been developed by a team in Sweden. These small particles can be loaded with medicine and could be a future weapon for cancer treatment. Because the particles can be seen in magnetic resonance images, they are traceable.
Switchable mirrors can be switched between a transparent state and a mirror state. Some types, which help reduce cooling loads in buildings by blocking sunlight, can be switched electrically. Some can be switch by way of a thin layer of gas that changes mirror properties through hydrogenation. A new type of switchable mirror has been developed in Japan that can control the reflection of visible to near-infrared light at a switching speed about 20 times faster than that of conventional electrochromic switchable glass.
Scientists in Australia are perfecting a technique that may help see nanodiamonds used in biomedical applications. They have been processing the raw diamonds so that they might be used as a tag for biological molecules and as a probe for single-molecule interactions. With the help of an international team, these diamonds have recently been optically trapped and manipulated in three dimensions—the first time this has been achieved.
The salinity difference between freshwater and saltwater could be a source of renewable energy. However, power yields from existing techniques are not high enough to make them viable. A team led by physicists in France has discovered a new means of harnessing this energy. Their method of osmotic flow through boron nitride nanotubes generates electric currents with 1,000 times the efficiency of any previous system.