Phys.org July 3, 2024 Phonon engineering at the nanoscale holds immense promise for a myriad of applications. However, the design of phononic devices continues to rely on regular shapes chosen according to long-established simple rules. Researchers in Japan demonstrated an inverse design approach to create a two-dimensional phononic metasurface exhibiting a highly anisotropic phonon dispersion along the main axes of the Brillouin zone. A partial hypersonic bandgap was present along one axis, with gap closure along the orthogonal axis which was achieved through genetically optimized unit cells, with shapes exceeding conventional intuition. They experimentally validated their theoretical predictions using Brillouin […]
High-selectivity graphene membranes enhance COâ‚‚ capture efficiency
Phys.org July 6, 2024 Although membranes based on a porous two-dimensional selective layer offer the potential to achieve exceptional performance to improve energy efficiency and reduce the cost for carbon capture, competitive sorption of CO2 with the potential to yield high permeance and selectivity has remained elusive. Researchers in Switzerland showed that a simple exposure of ammonia to oxidized single-layer graphene at room temperature incorporates pyridinic nitrogen at the pore edges. This led to a highly competitive but quantitatively reversible binding of CO2 with the pore. A combination of CO2/N2 separation factor and CO2 permeance from a stream containing 20 vol% […]
Inverse design method improves high-temperature performance of carbide coatings
Phys.org July 3, 2024 Researchers in China prepared the (Hf0.36Zr0.24Ti0.1Sc0.1Y0.1La0.1)C1-δ (HEC) coatings. The HEC possesses higher toughness with a higher Pugh’s ratio of 1.55 in comparison with HfC (1.30). The in-situ formed dense (Hf0.36Zr0.24Ti0.1Sc0.1Y0.1La0.1)O2-δ oxide scale during ablation benefits to improve the anti-ablation performance was attributed to its high structural adaptability with a lattice constant change not exceeding 0.19 % at 2000–2300 °C. According to the researchers the current investigation demonstrated the effectiveness of the inverse theoretical design, providing a novel optimization approach for ablation protection of high-entropy carbide coatings… read more. Open Access TECHNICAL ARTICLE
A management strategy for producing scientific breakthroughs
Phys.org July 2, 2024 A team of researchers in the UK identified the Laboratory of Molecular Biology’s (LMB’s) management model as the key — it sets a culture with incentives and provides oversight to optimize the interplay between science and technology. By integrating high-risk basic science with innovative technology, the LMB facilitates a knowledge feedback loop that helps the institute to identify promising questions and continuously push scientific boundaries. In the context of economics and management theory, the LMB behaves as a ‘complex adaptive system’. They outlined their findings and encourage research organizations, funding bodies and policymakers to consider adopting […]
New and improved camera inspired by the human eye
Science Daily July 1, 2024 Neuromorphic vision sensors or event cameras have made the visual perception of extremely low reaction time possible, opening new avenues for high-dynamic robotics applications. Human vision deals with perceptual fading using the active mechanism of small involuntary eye movements, the most prominent ones called microsaccades. By moving the eyes constantly and slightly during fixation, microsaccades can substantially maintain texture stability and persistence. An international team of researchers (USA – University of Maryland, China, Hong Kong) designed an event-based perception system capable of simultaneously maintaining low reaction time and stable texture. In their design, a rotating […]
New possibilities for reservoir computing with topological magnetic and ferroelectric systems
Phys.org July 3, 2024 Topological spin textures in magnetic materials and arrangements of electric dipoles in ferroelectrics are promising candidates for next-generation information technology and unconventional computing. Exciting examples are magnetic skyrmions and ferroelectric domain walls. In their article an international team of researchers (Germany, Norway) discussed how the physical properties of these topological nanoscale systems can be leveraged for reservoir computing, that is, for translating non-linear problems into linearly solvable ones. Topological nanoscale systems fulfill the requirements for non-linearity, complexity, short-term memory and reproducibility, giving new opportunities for the downscaling of devices, enhanced complexity and versatile input and readout […]
Novel 2D device for quantum cooling converts heat to voltage at ultra-low temperatures
Phys.org July 5, 2024 Nernst effect has potential for energy conversion achieving high performance and versatility at low temperatures. However, achieving high performance and versatility at low temperatures remains elusive. An international team of researchers (Switzerland, Japan) demonstrated a large and electrically tunable Nernst effect by combining the electrical properties of graphene with the semiconducting characteristics of indium selenide in a field-effect geometry. Photovoltage measurements revealed a stronger photo-Nernst signal in the graphene/indium selenide heterostructure compared with individual components. They observed a record-high Nernst coefficient at ultralow temperatures and low magnetic fields, an important step towards applications in quantum information […]
Researchers develop technology to mass produce quantum dot lasers for optical communications
Phys.org June 28, 2024 To produce 75 °C continuous-wave operation research in South Korea investigated InAs/GaAs quantum dot laser diodes (QDLDs) on a GaAs substrate grown by utilizing all-metalorganic chemical vapor deposition technology with a p-AlGaAs cladding layer. The InAs quantum dots (QDs) in a dot-in-a-well (DWELL) structure formed by engineering the strained bottom InGaAs layer were successfully grown without detectable clusters, making it possible to increase the number of DWELL stacks effectively. The results of electron-channeling contrast imaging revealed that dislocations in the p-cladding layer were generated due to the accumulative strain of the DWELL and low-temperature growth. The […]
Scientists achieve first intercity quantum key distribution with deterministic single-photon source
Phys.org July 3, 2024 Quantum key distribution (QKD) enables secure communication. Semiconductor quantum dots (QDs) are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution. Researchers in Germany reported on the first intercity QKD experiment using a bright deterministic single photon source. A BB84 [one time pad encryption] protocol based on polarisation encoding was realized using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure. Utilizing the 79 km long link (equivalent to 130 km for the […]
True scale of carbon impact from long-distance travel revealed
Phys.org July 2, 2024 Researchers in the UK characterized the long-distance travel pattern in England and explored its importance on carbon emissions from and decarbonization of passenger travel. They found that only 2.7% of a person’s trips are for long distance travel (>50 miles one-way), but they account for 61.3% of the miles and 69.3% of the greenhouse gas (CO2 equivalent) emissions from passenger travel. Flying for leisure and social purposes are the largest contributors to long distance miles and emissions. Overall, per capita travel emissions have started decreasing slowly from 2007, but are still higher than in 1997. They […]