COVID-19 can spread from asymptomatic but infected people through small aerosol droplets in their exhaled breath. Most studies of the flow of exhaled air have focused on coughing or sneezing; however, speaking while near one another is also risky. In Physics of Fluids, scientists used smoke and laser light to study the flow of expelled breath near and around two people conversing in various relative postures commonly found in the service industry.
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IMAGE: Researchers have developed a new sensor that uses an interband cascade light emitting device (ICLED) and could allow practical and low-cost detection of low concentrations of methane. view more
Credit: Sameer Khan
WASHINGTON Researchers have developed a new sensor that could allow practical and low-cost detection of low concentrations of methane gas. Measuring methane emissions and leaks is important to a variety of industries because the gas contributes to global warming and air pollution. Agricultural and waste industries emit significant amounts of methane, said Mark Zondlo, leader of the Princeton University research team that developed the sensor. Detecting methane leaks is also critical to the oil and gas industry for both environmental and economic reasons because natural gas is mainly composed of methane.
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IMAGE: The definition of χ in systems with S4 symmetry on the orange surface S. The system in (b) has C2,110 symmetry. view more
Credit: @Science China Press
Using the symmetries of the systems, people can define various topological invariants to describe different topological states. The topological materials can be accurately discovered by calculating the topological invariants. Recently, researchers found that irreducible representations and compatibility relationships can be used to determine whether a material is topological nontrivial/trivial insulator (satisfying the compatibility relations) or topological semimetal (violating the compatibility relations), which leads to a large number of topological materials predicted by theoretical calculations. However, Weyl semimetals go beyond this paradigm because the existence of Weyl fermions does not need any symmetry protections (except for lattice translation symmetries). At present, people usually take a ve
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IMAGE: a, the hybrid Kagome-tubular HCPCF cross-section, b, enlarged view of the connecting region between the inner and outer cladding, c, loss measurement results (blue curve), and simulated confinement loss (CL). view more
Credit: by Foued Amrani, Jonas H. Osório, Frédéric Delahaye, Fabio Giovanardi, Luca Vincetti, Benoît Debord, Frédéric Gérôme, Fetah Benabid.
Recent spotlights on IC-HCPCFs are due to the recently demonstrated outstanding ultralow-loss performances and their application capabilities. Nevertheless, while their attenuation achieves impressive figures, the challenge of accomplishing a low loss, single-mode (SM), and polarization-maintaining HCPCF perseveres.
In a new paper published in
Biological systems can harness their living cells for growth and regeneration, but engineering systems cannot. Until now.Researchers are harnessing living bacteria to create engineering materials that are strong, tolerant, and resilient.