[Image above] Credit: NIST
The mantis shrimp is able to repeatedly pummel the shells of prey using a hammer-like appendage that can withstand rapid-fire blows by neutralizing certain frequencies of “shear waves,” according to new research by University of California, Riverside and Purdue University engineers. The club is made of a composite material containing fibers of chitin, the same substance found in many marine crustacean shells and insect exoskeletons but arranged in a helicoidal structure that resembles a spiral staircase.
Finding an efficient solar water splitting method to mine electron-rich hydrogen for clean power has been thwarted by the poor performance of hematite. But by ‘re-growing’ the mineral’s surface, a smoother version of hematite doubled electrical yield, opening a new door to energy-harvesting artificial photosynthesis. Re-grown hematite proved to be a better power-generating anode, producing a record low turn-on voltage that enabled the researchers to be the first to use earth-abundant hematite and silicon as the sole light absorbers in artificial photosynthesis.
A multi-institutional team of scientists has taken an important step in understanding where atoms are located on the surfaces of rough materials, information that could be very useful in diverse commercial applications, such as developing green energy and understanding how materials rust. The team has developed a new imaging technique that uses atomic resolution secondary electron images in a quantitative way to determine the arrangement of atoms on the surface.
MIT researchers have created animations that show the swelling associated with lithium ions flowing into the cathode or anode material, which is called intercalation. The swelling causes mechanical stress on the material, which can lead to incomplete absorption of available lithium ions and lessen a battery’s ability to hold a charge. The work also shows that inhomogeneous mechanical stress causes lithium to concentrate in areas of higher tensile stress and migrate away from regions where the material is compressed.
Materials melt faster when the lines of heat spread through the cold material like the branches of a tree—and the melting rate can be steadily increased by allowing the tree architecture to freely evolve over time, researchers have discovered. The finding could help improve phase change energy storage systems, which store heat by melting materials like wax or salt, and could play an important role in ensuring a smooth flow of energy from renewable sources like the wind and sun.