Nanowerk July 9, 2021 A team of researchers in the US (UCLA, UC Irvine) explored the interface energy transport in semiconductor materials with high thermal conductivity, including boron arsenide (BAs) and boron phosphide (BP). They showed that BAs and BP cooling substrates can be heterogeneously integrated with metals, a wide-bandgap semiconductor (gallium nitride, GaN) and high-electron-mobility transistor devices. GaN-on-BAs structures exhibit a high thermal boundary conductance of 250 MW m−2 K−1, and comparison of device-level hot-spot temperatures with length-dependent scaling (from 100 μm to 100 nm) shows that the power cooling performance of BAs exceeds that of reported diamond devices. Operating AlGaN/GaN high-electron-mobility transistors with […]
The demonstration of ultrafast switching to an insulating-like metastable state
Phys.org July 13, 2021 Superconductors host collective modes that can be manipulated with light. An international team of researchers (Japan, France) has shown that a strong terahertz light field can induce oscillations of the superconducting order parameter in NbN with twice the frequency of the terahertz field. The result can be captured as a collective precession of Anderson’s pseudospins in ac driving fields. A resonance between the field and the Higgs amplitude mode of the superconductor then results in large terahertz third-harmonic generation. Their method paves a way toward nonlinear quantum optics in superconductors with driving the pseudospins collectively and […]
Discovery of 10 faces of plasma leads to new insights in fusion and plasma science
Phys.org July 13, 2021 Researchers at Princeton University systematically mapped out all the topological phases of cold magnetized plasmas and established the bulk-edge correspondence. They found that for the linear eigenmodes, there are 10 topological phases in the parameter space of density n, magnetic field B, and parallel wavenumber kz, separated by the surfaces of Langmuir wave-L wave resonance, Langmuir wave-cyclotron wave resonance, and zero magnetic field. For fixed B and kz, only the phase transition at the Langmuir wave-cyclotron wave resonance corresponds to edge modes. A sufficient and necessary condition for the existence of this type of edge modes […]
Electrons in quantum liquid gain energy from laser pulses
Phys.org July 13, 2021 Laser-assisted electron scattering (LAES), a light–matter interaction process that facilitates energy transfer between strong light fields and free electrons, has so far been observed only in gas phase. An international team of researchers (Austria, Japan) has detected LAES at condensed phase particle densities, for which they created nano-structured systems consisting of a single atom or molecule surrounded by a superfluid He shell of variable thickness. They observed that free electrons, generated by femtosecond strong-field ionization of the core particle, can gain several tens of photon energies due to multiple LAES processes within the liquid He shell. […]
Global evidence links rise in extreme precipitation to human-driven climate change
Phys.org July 7, 2021 Detecting anthropogenic forcing is difficult to detect in observational record. Researchers at UCLA used artificial neural networks to find patterns of extreme precipitation in weather records. They found multiple lines of evidence that human activity has intensified extreme precipitation during recent decades. Even when the data sets were widely different, they were able to see the human influence…read more. Open Access TECHNICAL ARTICLE
Harnessing the dark side
Nanowerk July 13, 2021 Optical singularities, which appear completely dark, typically occur when the phase of light with a specific wavelength, or color, is undefined. Researchers at Harvard University have developed a new way to control and shape optical singularities. The metasurface tilts the wavefront of light in a very precise manner over a surface so that the interference pattern of the transmitted light produces extended regions of darkness. Their approach allows precise engineering of dark regions with remarkably high contrast. Engineered singularities could be used to trap atoms in dark regions and improve super high-resolution imaging. As darkness has […]
The hidden culprit killing lithium-metal batteries from the inside
EurekAlert July 14, 2021 A team of researchers in the US (Sandia National Laboratory, University of Oregon, industry, Lawrence Berkeley National Laboratory) repeatedly charged and discharged lithium coin cells with the same high-intensity electric current that electric vehicles need to charge. Using cryogenic femtosecond laser cross sectioning and subsequent scanning electron microscopy, they observed the electroplated Li-metal morphology and the accompanying solid electrolyte interphase (SEI) into and through the intact coin cell battery’s separator, gradually opening pathways for soft-short circuits that cause failure. They found that separator penetration by the SEI guided the growth of Li dendrites through the cell. […]
Licensing Opportunity: Virus-Like Particle Technology for Universal Flu Vaccine
Global Biodefense July 13, 2021 The National Institutes of Health (NIH) has a Technology Transfer opportunity available for a virus-like particle (VLP) vaccine technology for influenza viruses, based on a mixture of VLPs expressing the hemagglutinin protein or the neuraminidase protein from influenza virus strains belonging to different virus subtypes. The technology has demonstrated broad protection against lethal challenge in mice with various influenza virus strains and virus subtypes. Results from ferret and mouse studies demonstrate broad heterosubtypic protection against various influenza virus subtypes, further supporting and strengthening the proposed application of this technology as a universal influenza virus vaccine…read […]
New ‘Metafabric’ Passively Cools The Human Body by Almost 5 Degrees Celsius
Science Alert July 13, 2021 The metafabric developed by researchers in China uses titanium oxide-polylactic acid composite nanoparticles laminated with a thin layer of polytetrafluoroethylene (PTFE). It is designed to strongly reflect visible light (VIS), mid-infrared (MIR) and ultraviolet (UV) ranges. The wide distribution of nanoparticles, when combined with PTFE nanobeads, provides broad-spectrum scattering and reflectivity across the UV-VIS-NIR band. They tested the material in clear sky conditions measuring the temperature of the fabric in comparison to other common materials lying on a panel. Under peak solar irradiance between 11:00 and 15:00, the temperature of the metafabric was approximately 5.0°, […]
Mosquito-resistant clothing prevents bites in trials
Phys.org July 13, 2021 An international team of researchers (USA – North Carolina State University, Germany) has developed a mathematical model for fabric barriers that resist bites from Aedes aegypti mosquitoes based on textile physical structure and no insecticides. The model was derived from mosquito morphometrics and analysis of mosquito biting behavior. Woven filter fabrics, precision polypropylene plates, and knitted fabrics were used for model validation. Based on the model predictions, prototype knitted textiles and garments were developed that prevented mosquito biting, and comfort testing showed the garments to possess superior thermophysiological properties. The fabrics provided a three-times greater bite […]