Phys.org November 7, 2024 Researchers in Germany derived a general theory of the viscosity of gases based on the relativistic Langevin equation and nonaffine linear response theory. The proposed relativistic theory was able to recover the viscosity of nonrelativistic classical gases, with all its key dependencies on mass, temperature, particle diameter, and Boltzmann constant, in the limit of Lorentz factor =1. It also unveiled the relativistic enhancement mechanism of viscosity. According to the researchers in the limit of ultra relativistic fluids, the theory provides an analytical formula which reproduces the cubic increase of viscosity with temperature in agreement with various […]
In step forward for quantum computing hardware, IU physicist uncovers novel behavior in quantum-driven superconductors
EurekAlert November 12, 2024 An international team of researchers (India, USA – Indiana University) studied the transport signatures of unpaired Floquet Majorana fermions in the Josephson current of weakly linked, periodically driven topological superconductors. They obtained analytical expressions for the occupation of the Floquet Majorana fermions in the presence of weak coupling to thermal reservoirs, and showed that, similar to undriven topological superconductors, for sufficiently low temperatures and large systems the Josephson current involving Floquet Majorana fermions is in the phase difference across the junction and depends linearly on the coupling between superconductors. Unlike the static case, the amplitude of […]
Measurements from ‘lost’ Seaglider offer new insights into Antarctic ice melting
Phys.org November 8, 2024 Solar-warmed surface waters subduct beneath Antarctica’s ice shelves because of wind forcing, but this process is poorly observed and its interannual variability is yet to be assessed. Researchers in the UK observed a 50-meter-thick intrusion of warm surface water immediately beneath the Ross Ice Shelf. Temperature in the uppermost 5 meters decreased toward the ice base in near-perfect agreement with an exponential fit, consistent with the loss of heat to the overlying ice. They found that Ekman forcing drove a heat transport into the cavity sufficient to contribute considerably to near-front melting; this transport increased over […]
MIT engineers make converting CO2 into useful products more practical
MIT News November 13, 2024 Electrochemical CO2 reduction has emerged as a promising CO2 utilization technology, with Gas Diffusion Electrodes becoming the predominant architecture to maximize performance. The electrodes must maintain robust hydrophobicity to prevent flooding, while also ensuring high conductivity to minimize ohmic losses. Researchers at MIT demonstrated a hierarchically conductive electrode architecture which overcame the scaling limitations by employing inter-woven microscale conductors within a hydrophobic expanded Polytetrafluoroethylene membrane. They developed a model which captured the spatial variability in voltage and product distribution on electrodes due to ohmic losses and used it to rationally design the hierarchical architecture which […]
Nanoscale transistors could enable more efficient electronics
MIT News November 4, 2024 A range of novel transistor concepts have been explored for the development of data-centric computing for energy-efficient electronics that can overcome the fundamental limitations of conventional silicon transistors. However, an approach that can simultaneously offer high drive current and steep slope switching while delivering the necessary scaling in footprint is still lacking. An international team of researchers (USA – MIT, France, Italy) developed scaled vertical-nanowire heterojunction tunnelling transistors that were based on the broken-band GaSb/InAs system. The approach relies on extreme quantum confinement at the tunnelling junction and was based on an interface-pinned energy band […]
Physicists create tiny hurricanes of light that could transport huge amounts of data
Phys.org November 11, 2024 Photonic modes exhibiting polarization winding akin to a vortex possess an integer topological charge. Lasing with topological charge 1 or 2 can be realized in periodic lattices of up to six-fold rotational symmetry—higher order charges require symmetries not compatible with any two-dimensional Bravais lattice. Researchers in Finland experimentally demonstrated lasing with topological charges as high as −5, +7, −17 and +19 in quasicrystals. They discovered rich ordered structures of increasing topological charges in reciprocal space. Their quasicrystal design utilized group theory in determining electromagnetic field nodes, where lossy plasmonic nanoparticles were positioned to maximize gain. According […]
Physicists reveal how layers and twists impact graphene’s optical conductivity
Phys.org November , 2024 An international team of researchers (USA – Florida State University, China) explored the advantages of moiré superlattices in twisted bilayer graphene (TBG) aligned with hexagonal boron nitride (hBN) for passively enhancing optical conductivity in the low-energy regime. To probe the local optical response of TBG/hBN double-moiré lattices, they used infrared nano-imaging in conjunction with nanocurrent imaging to examine local optical conductivity over a wide range of TBG twist angles. They showed that interband transitions associated with the multiple moiré flat and dispersive bands produced tunable transparent IR responses even at finite carrier densities, which is in […]
Plastic-eating insect discovered in Kenya
Phys.org November 11, 2024 Researchers in Kenya evaluated the ability of the mealworm to consume Polystyrene (PS) its associated gut microbiota diversity. During the PS feeding trials intake increased over a 30-day period and the overall survival rates of the larvae decreased when fed a sole PS diet. The predominant bacteria observed in larvae fed PS diets were Kluyvera, Lactococcus, Klebsiella, Enterobacter, and Enterococcus, while Stenotrophomonas dominated the control diet. According to the researchers their findings demonstrated that the newly identified lesser mealworm could survive on a PS diet and has a consortium of important bacteria strongly associated with PS […]
Scientists capture images of a new quantum phase in electron molecular crystals
Phys.org November 17, 2024 Semiconductor Moiré superlattices provide a versatile platform to engineer quantum solids composed of artificial atoms on moiré sites. Previous studies have mostly focused on the simplest correlated quantum solid—the Fermi-Hubbard model—in which intra-atom interactions are simplified to a single onsite repulsion energy. An international team of researchers (USA – UC Berkeley, Lawrence Berkeley National Laboratory, MIT, University of Arizona, Japan) experimentally observed Wigner molecular crystals emerging from multielectron artificial atoms in twisted bilayer tungsten disulfide moiré superlattices. Using scanning tunneling microscopy, they demonstrated that Wigner molecules appeared in multielectron artificial atoms when Coulomb interactions dominated. The […]
Scientists unlock mechanisms of liquid-repellent surfaces
Phys.org November 11, 2024 Understanding and controlling liquid interactions on tiny, advanced surfaces, a breakthrough that could impact a wide range of industries, from self-cleaning materials to medical devices. Through experimental approaches and theoretical analysis, a team of researchers in Australia assessed how variations in geometry and material impact wettability. Key findings revealed that SiC re-entrant structures had similar hydrophobic behavior. Although flat SiC surfaces exhibited higher inherent hydrophobicity than flat SiO₂, re-entrant geometry predominantly influenced wetting behavior. Structures with lower solid area fractions showed increased hydrophobicity, with a distinct hierarchy: micro lines were the least hydrophobic, followed by shark-skin […]