DARPA News June 9, 2020 To break the dependence on big antennas and amplifiers for establishing long-range tactical communications for U.S. troops in remote locations, DARPA recently announced the Resilient Networked Distributed Mosaic Communications (RN DMC) program which aims to provide long-range communications through “mosaic” antennas composed of spatially distributed low SWaP-C transceiver elements or “tiles.” This approach replaces high-powered amplifiers and large directional antennas with mosaics of dispersed tile transceivers. Transmit power is distributed among the tiles, and gain is achieved through signal processing rather than by a physical antenna aperture to concentrate energy. The antenna mosaic concept could […]
Metasurface opens world of polarization
Science Daily June 3, 2020 To achieve broad polarization manipulation, multiple birefringent materials need to be stacked one top of another making these devices bulky and inefficient. Researchers at Harvard University used topological optimization to design birefringent materials. They started with the functionality of the metasurface and allowed the algorithm to explore the huge parameter space to develop a pattern that can best deliver that function. The resulting metasurface was composed of nested half circles. The odd shapes have opened a whole new world of birefringence. They can achieve broad polarization manipulations; polarization can be tuned by changing the angle […]
Quantum ‘fifth state of matter’ observed in space for first time
Phys.org June 11, 2020 Scientists believe Bose-Einstein Condensates (BEC) contain vital clues to mysterious phenomena such as dark energy. As they are extremely fragile it is nearly impossible for scientists to study BEC on Earth, where gravity interferes with the magnetic fields required to hold them in place for observation. Last week a team of NASA scientists unveiled the first results from BEC experiments aboard the International Space Station, where particles can be manipulated. An international team of researchers (USA -Caltech, Germany) documents several startling differences in the properties of BECs created on Earth and those aboard the ISS. BECs […]
Reality check: COVID-19 and UV disinfection
Physics World June 11, 2020 In moderate doses UVA and UVB are good for us in several ways. The ozone layer filters out more dangerous band of sunlight UVC. As well as damaging skin, UVC can also mangle the genetic material of viruses and bacteria, preventing them from reproducing. During the COVID-19 outbreak in China, buses were even bathed in UV light overnight. Because of the high risk to humans, operators wear hardcore safety equipment and go through specialized training. Researchers have discovered that a specific wavelength of UVC light – 222 nm – could be much less dangerous to […]
Researchers advance fuel cell technology
Science Daily June 8, 2020 A team of researchers in the US (Washington State University, UMass Lowell, Stony Brook, Brookhaven National Laboratory, Pacific Northwest National Laboratory) used an inexpensive catalyst made from nickel and then added molybdenum nanoparticles as a dopant to make a fuel cell. In tests the fuel cell was able to run for 24 hours straight without failing. The system was resistant to carbon build-up and sulfur poisoning. Fuel cells that run on gasoline tend to build up carbon within the cell, stopping the conversion reaction. Other chemicals that are common in liquid fuels, such as sulfur, […]
Researchers develop viable sodium battery
Science Daily June 1, 2020 An international team of researchers (USA – Pacific Northwest National Laboratory, Brookhaven National Laboratory, Washington State University, China) created a layered metal oxide cathode and a liquid electrolyte that included extra sodium ions. The cathode design and electrolyte system allowed for continued movement of sodium ions, preventing inactive surface crystal build-up, and allowing for unimpeded electricity generation. The research revealed the essential correlation between cathode structure evolution and surface interaction with the electrolyte. They are working to better understand the important interaction between the electrolyte and the cathode, so they can work with different materials […]
Scientists apply ‘twistronics’ to light propagation and make a breakthrough discovery
Nanowerk June 11, 2020 As recent research showed how superconductivity is achieved in a pair of stacked graphene layers that were rotated to the “magic twist angle” and careful control of rotational symmetries can unveil unexpected material responses. Now an international team of researchers (Singapore, USA – City University of New York, Australia, China) has discovered that an analogous principle can be applied to manipulate light in highly unusual ways. They stacked two thin sheets of molybdenum trioxide and rotated one of the layers with respect to the other. When the materials were excited by a tiny optical emitter, they […]
Surprisingly strong and deformable silicon
EurekAlert June 10, 2020 Silicon is very brittle which can become a problem when trying to make MEMS from silicon, such as the acceleration sensors in smartphones. Researchers in Switzerland have demonstrated that Si processed by modern lithography procedures exhibits an ultrahigh elastic strain limit, near ideal strength (shear strength ~4 GPa) and plastic deformation at the micron-scale, one order of magnitude larger than samples made using focused ion beams, due to superior surface quality. This extended elastic regime enables enhanced functional properties by allowing higher elastic strains to modify the band structure. Further, the micron-scale plasticity of Si allows the investigation […]
Three research groups, two kinds of electronic properties, one material
Science Daily June 10, 2020 An international team of researchers (Israel, Germany) has shown that Bi2TeI (bismuth, tellurium and iodine ) is a dual topological insulator. It exhibits band inversions at two-time reversal symmetry points of the bulk band, which classify it as a weak topological insulator with metallic states on its ‘side’ surfaces. The mirror symmetry of the crystal structure concurrently classifies it as a topological crystalline insulator. They show the existence of both two-dimensional Dirac surface states, which are susceptible to mirror symmetry breaking, and one-dimensional channels that reside along the step edges. Their mutual coexistence on the […]
Ultra-thin camera lenses of the future could see the light of day
Nanowerk June 11, 2020 The fabrication of state-of-the-art metasurfaces typically involves several expensive, time-consuming, and potentially hazardous processing steps. Researchers in Sweden have developed a method to construct phase-gradient metasurfaces from an exposed standard electron beam resist. They demonstrated the advantages of the method by constructing high-performance flat optics for the entire visible wavelength range. The method dramatically cuts the required processing time, cost, and reduces safety hazards. The method could be a step towards large-scale production of metasurfaces…read more. Open Access TECHNICAL ARTICLE