Phys.org April 27, 2020 Hyperbolic metasurfaces (HMTSs) are known to support confined surface waves collimated toward specific directions determined by the metasurface dispersion. By rotating two evanescently coupled HMTSs with respect to one another, an international team of researchers (USA – University of New York, UT Austin, Singapore) unveil rich dispersion engineering, topological transitions at magic angles, broadband field canalization, and plasmon spin-Hall phenomena. These findings open remarkable opportunities to advance metasurface optics, enriching it with moiré physics and twistronic concepts…read more. TECHNICAL ARRTICLE
Stretchable lithium-ion battery is based on new micro-honeycomb structure
Nanowerk April 29, 2020 In stretchable batteries the electrodes must have a degree of stretchability because the active materials occupy most of the volume, and the separator and packaging should also be stretchable. Researchers in South Korea have developed an all-component stretchable lithium-ion battery by leveraging the structural stretchability of re-entrant micro-honeycomb graphene–carbon nanotube (CNT)/active material composite electrodes and a physically cross-linked gel electrolyte, without using an inactive elastomeric substrate or matrix. Active materials interconnected via the entangled CNT and graphene sheets provided a mechanically stable porous network framework consisting solely of binder-free, highly conductive materials which provided superior electron […]
UCF researchers develop groundbreaking new rocket-propulsion system
EurekAlert April 30, 2020 A team of researchers in the US (University of Central Florida. industry, Air Force Research Laboratory) presents experimental evidence of continuous detonation in a rotating detonation rocket engine (RDRE) powered by H2/O2 propellants. High-speed chemiluminescence imaging is used to characterize the detonation wave dynamics by introducing a tracer in the hydrogen fuel flow. The results show continuous five-wave co-rotating detonations at various equivalence ratios and flow rates demonstrating the potential for H2/O2 propellant based RDREs for upper-stage rocket engines…read more. TECHNICAL ARTICLE
Unlocking promising properties to create future technologies
EurekAlert April 30, 2020 The manifestation of quantization in macroscopic physical systems has showcased important quantum phenomena, such as quantized conductance in (fractional) quantum Hall effects and quantized vortices in superconductors. An international team of researchers (USA – Rensselaer Polytechnic Institute, Florida State University, UT Dallas, Arizona State University, Japan, Hong Kong) reported the experimental observation of quantized exciton energies in a macroscopic system with strong Coulomb interaction, monolayer WSe2 crystal under a strong magnetic field. This work demonstrates the optical version of the QHE for excitons, and the researchers believe it will open the door for further discovery and […]
‘Wobble’ may precede some great earthquakes
Science Daily April 29, 2020 The land masses of Japan shifted from east to west to east again in the months before the strongest earthquake in the country’s recorded history, a 2011 magnitude-9 earthquake. An international team of researchers (Germany, Chile, USA- Ohio State University) analyzed the “wobble,” may have the potential to alert seismologists to greater risk of future large subduction-zone earthquakes. The imperceptible movement was obvious in data recorded by more than 1,000 GPS stations distributed throughout Japan, in the months leading up to the March 11 Tohoku-oki earthquake. They saw a reversing shift in the land — […]
Top 10 Science and Technology Inventions for the Week of April 24, 2020
01. Researchers identify cells likely targeted by Covid-19 virus 02. A breakthrough in estimating the size of a (mostly hidden) network 03. Wide-band-gap semiconductors could harvest sunlight underwater 04. Electrical manipulation of magnetic particle allows for large high-speed memory 05. Photonic microwave generation using on-chip optical frequency combs 06. Quantum entanglement offers unprecedented precision for GPS, imaging and beyond 07. Toward a more energy-efficient spintronics 08. Drones Use Radio Waves to Recharge Sensors While in Flight 09. New ‘brick’ for nanotechnology: Graphene Nanomesh 10. Unprecedented 3D images of live cells plus details of molecules inside And others… Aquaculture at the […]
Wide-band-gap semiconductors could harvest sunlight underwater
Physics World April 17, 2020 Using detailed-balance calculations researchers at the University of New York have shown that underwater solar cells can exhibit efficiencies from ∼55% in shallow waters to more than 65% in deep waters, while maintaining a power density >5 mW cm −2. They showed that the optimum band gap of the solar cell shifts by ∼0.6 eV between shallow and deep waters and plateaus at ∼2.1 eV at intermediate depths, independent of geographical location. This wide range in optimum band-gap energies opens the potential for a library of wide-band-gap semiconductors to be used for high-efficiency underwater solar […]
Aquaculture at the crossroads of global warming and antimicrobial resistance
Science Daily April 20, 2020 Fish farmers use large quantities of antimicrobials to treat or prevent disease on their farms. However, when used inappropriately, antimicrobials are ineffective and foster the development of resistant bacteria. An international team of researchers (France, Germany) conducted a double meta-analysis to explore how global warming and antimicrobial resistance impact aquaculture. They calculated a Multi-Antibiotic Resistance index (MAR) of aquaculture-related bacteria for 40 countries. They showed that aquaculture MAR indices correlate with MAR indices from human clinical bacteria, temperature and countries’ climate vulnerability and infected aquatic animals present higher mortalities at warmer temperatures. They raise the […]
A breakthrough in estimating the size of a (mostly hidden) network
Phys.org April 22, 2020 For homogeneous networks accessing a mere 10% of the units could be sufficient to exactly infer the size of the entire network. But the same approach fails for heterogeneous networks, which are far more common in the field of complex systems. Researchers at New York University present a model-free approach to address this problem by studying the rank of a detection matrix that collates sampled time series of perceptible nodes from independent experiments. They unveil a connection between the rank of the detection matrix and the control-theoretic notion of observability. With this information it is to […]
Drones Use Radio Waves to Recharge Sensors While in Flight
IEEE Spectrum April 17, 2020 An international team of researchers (Lebanon, Italy) has developed and implemented a RF energy harvesting and wake-up system that scavenges a 2.4 GHz signal from a UAV. It can deliver power wirelessly to remote sensors. The signal transmitted by the UAV is harvested and rectified to DC voltage to power a sensor on the ground. Additionally, the UAV modulates the transmitted signal to encode an address that triggers a particular sensor from sleep mode to active mode. Charging can be initiated from input power levels as low as -18.2~dBm and a sensor can be triggered […]