Phys.org January 24, 2023 Most studies using the GHz burst mode femtosecond laser pulses focus on ablation of materials to achieve high-efficiency and high-quality material removal. Researchers in Japan explored the ability of the GHz burst mode femtosecond laser processing to form laser-induced periodic surface structures (LIPSS) on silicon. The direction of LIPSS formed by the single-pulse mode with linearly polarized laser pulses is typically perpendicular to the laser polarization direction. They showed that the GHz burst mode femtosecond laser created unique two-dimensional LIPSS. The team has proposed a possible mechanism for the formation of 2D LIPSS formed by the […]
Half-century of cyclone data puts researchers on track to explore future risks
Phys.org January 19, 2023 Tropical cyclones (TCs) with genesis in the Coral Sea present significant hazards to coastal regions in their surroundings. In addition, the erratic nature of TC tracks is not well understood in this region. Researchers in Australia grouped Coral Sea TC tracks over the last fifty years based on K-means clustering of the maximum wind-weighted centroids to extract valuable new cyclone power, track curvature and location related information to predict their behaviour. They assessed the TC track variance and curvature (sinuosity) and identified three well-defined clusters of TC tracks. The results showed differing predominant directions of TC […]
Models show Tonga eruption increases chances of global temperature rising temporarily above 1.5 C
Phys.org January 25, 2023 On 15 January 2022, the Hunga Tonga–Hunga Ha’apai (HTHH) eruption injected 146 MtH2O and 0.42 MtSO2 into the stratosphere. This large water vapour perturbation means that HTHH will probably increase. An international team of researchers (UK, Austria) estimated the radiative response to the HTHH eruption and derived the increased risk that the global mean surface temperature anomaly shortly exceeds 1.5 °C following the eruption. They showed that HTHH has a tangible impact of the chance of imminent 1.5 °C exceedance (increasing the chance of at least one of the next 5 years exceeding 1.5 °C by 7%), but the level of climate […]
Multimillion-dollar trade in paper authorships alarms publishers
Nature 18 January 2023 An international team of researchers (Germany, UK) have uncovered hundreds of online advertisements that offer the chance to buy authorship on research papers to be published in reputable journals. Publishers and journals are investigating the claims and have retracted dozens of articles over suspicions that people have paid to be named as authors, despite not participating in the research. In July 2022, the International Journal of Emerging Technologies in Learning retracted 30 papers linked to adverts on International Publisher. In May 2022, Springer Nature retracted a paper for the first time over suspicions that some of […]
New shield blocks electromagnetic interference while allowing wireless optical signals
Phys.org January 25,2023 An international team of researchers (Sweden, China) experimentally demonstrated, for the first time, a mechanically flexible silver mesh that is visibly transparent, allows high-quality infrared wireless optical communication and efficiently shields electromagnetic interference in the X band portion of the microwave radio region. The Ag mesh/polyethylene (PE) achieved high average EMI shielding effectiveness (SE) of 28.8 dB in the X band with an overall transmittance of 80.9% at 550 nm. With a polydimethylsiloxane (PDMS) coating, the average EMI SE was still up to 26.2 dB and the overall transmittance was increased to 84.5% at 550 nm due […]
Novel method helps recover obscured images
Phys.org January 23, 2023 Imaging through scattering medium is challenging. Computational reconstruction from scattered signals is used frequently. An international team of researchers (China, Saudi Arabia) has experimentally demonstrated reconstruction-free real-time imaging of static and moving objects with their actual orientation information under single-wavelength and white light illumination. They proposed a modified speckle autocorrelation imaging (SAI) method inspired by the self-imaging results. According to the researchers their strategy does not requires pre-calibration or acquisition of point-spread-function, active control of wavefronts, complicated equipment, iterations or carefully adjusted parameters. The work could pave the way towards rapid and high-quality imaging through scattering […]
Photonic hopfions: Light shaped as a smoke ring that behaves like a particle
Phys.org January 19, 2023 Achieving hopfions with light waves is very elusive. An international team of researchers (UK, China) proposed and demonstrated photonic counterparts of hopfions with exact characteristics of Hopf vibration, Hopf index, and Hopf mapping from real-space vector beams to homotopic hyperspheres representing polarization states. They experimentally generated photonic hopfions with on-demand high-order Hopf indices and independently controlled topological textures, including Néel-, Bloch-, and antiskyrmionic types. They also demonstrated a robust free-space transport of photonic hopfions, thus showing the potential of hopfions for developing optical topological informatics and communications. According to the researchers their work provides a theoretical […]
Scientists demonstrate quantum recoil for the first time, paving the way for precise X-ray imaging
Phys.org January 19, 2023 More than 80 years after quantum recoil was proposed researchers in Singapore have demonstrated the phenomenon of quantum recoil showing that it is observable at room temperature. By scattering free electrons off the periodic two-dimensional atomic sheets of van der Waals materials in a tabletop platform, they showed that the X-ray photon energy is accurately predicted only by quantum recoil theory, that it can be enormous, to the point that a classically predicted X-ray photon is emitted as an extremely low-energy photon. According to the researchers quantum recoil is a means of precision control over outgoing […]
Scientists observe ‘quasiparticles’ in classical systems for the first time
Phys.org January 26, 2023 The concept of quasiparticles has become a cornerstone of condensed quantum matter, where it explains a variety of emergent many-body phenomena such as superfluidity and superconductivity. Researchers in South Korea used quasiparticles to explain the collective behaviour of a classical system of hydrodynamically interacting particles in two dimensions. In the disordered phase of this matter, measurements revealed a subpopulation of long-lived particle pairs. Modelling and simulation of the ordered crystalline phase identified the pairs as quasiparticles, emerging at the Dirac cones of the spectrum. The quasiparticles stimulated supersonic pairing avalanches, bringing about the melting of the […]
Scientists unveil least costly carbon capture system to date
Science Daily January 23, 2023 Rigorous process modeling and techno-economic analyses are limited for emerging carbon capture technologies. A team of researchers in the US (PNNL, industry, Washington State University) has developed four CO2-Binding Organic Liquids (CO2BOLs), all water-lean solvents, as promising options towards energy-effective and low-cost carbon capture from point sources. CO2BOLs can capture up to 97–99% CO2 from coal fired plant. The estimated carbon capture cost is about 12–23% less expensive than the conventional aqueous amine technology. In addition to vapor liquid equilibrium and kinetics (key properties for aqueous solvents), viscosity, volatility, and hydrophobicity, also have strong impacts […]