Phys.org June 30, 2021 An international team of researchers (Israel, Japan) reports a stable ferroelectric order emerging at the interface between two naturally grown flakes of hexagonal boron nitride, which were stacked together in a metastable non-centrosymmetric parallel orientation. They observed alternating domains of inverted normal polarization, caused by a lateral shift of one lattice site between the domains. Reversible polarization switching coupled to lateral sliding was achieved by scanning a biased tip above the surface. Their calculations trace the origin of the phenomenon to a subtle interplay between charge redistribution and ionic displacement and provide intuitive insights to explore […]
Top 10 Science and Technology Inventions for the Week of June 25, 2021
01. Researchers propose the use of quantum cascade lasers to achieve private free-space communications 02. Mining precious rare-earth elements from coal fly ash with a reusable ionic liquid 03. Outstanding organic solar cells’ performance achieved by using new technology 04. Perovskite memory devices with ultra-fast switching speed 05. Ocean Microbes May Actually Help Moderate Earth’s Temperature, Scientists Say 06. A bright future: Using visible light to decompose CO2 with high efficiency 07. Inkjet printing ‘impossible materials’ 08. Meringue-like material could make aircraft as quiet as a hairdryer 09. Sound-induced electric fields control the tiniest particles 10. Researchers develop a model […]
A bright future: Using visible light to decompose CO2 with high efficiency
Science Daily June 21, 2021 AgIO3 is useful for the CO2 reduction reaction. However, it needs much higher energy than what visible light can provide to function as an efficient photocatalyst. Researchers in Japan developed a new photocatalyst that incorporates single-walled carbon nanotubes (SWCNTs) with AgIO3 and AgI to form a three-component composite catalyst which solve both the synthesis and the electron transfer pathway problems. Spectroscopic observations using the composite showed that during the synthesis process, the encapsulated iodine molecules received charge from the SWCNT and converted into specific ions. They reacted with AgNO3 to form AgI and AgIO3 microcrystals, […]
A Coronavirus Epidemic Hit Humanity 20,000 Years Ago, DNA Study Reveals
Science Alert June 24, 2021 Modern human genomes contain evolutionary information tracing back tens of thousands of years, which may help identify the viruses that have impacted our ancestors—pointing to which viruses have future pandemic potential. An international team of researchers (Australia, USA – University of Arizona, UCSF) applied evolutionary analyses to human genomic datasets to recover selection events involving tens of human genes that interact with coronaviruses, including SARS-CoV-2, that likely started more than 20,000 years ago. These adaptive events were limited to the population ancestral to East Asian populations. Multiple lines of functional evidence support an ancient viral […]
The first observation of the superscattering effect of metamaterials
Phys.org June 23, 2021 Superscattering effects, such as stopping wave propagation in an air channel, have not been verified from illusion devices physically because of the challenge of metamaterial design, fabrication, and material loss. Researchers in China have implemented a big metamaterial superscatterer, and experimentally demonstrated its superscattering effect at microwave frequencies by field-mapping technology. They confirmed that superscattering is originated from the excitation of surface plasmons. They experimentally showed that an invisible gateway integrated with superscatterer could stop electromagnetic waves in an air channel with a width much larger than the cutoff width of the corresponding rectangular waveguide. The […]
Harvesting drinking water from humid air around the clock
Science Daily June 23, 2021 Researchers in Switzerland have designed and demonstrated a system that synergistically combines radiative shielding and cooling with a fully passive superhydrophobic condensate harvester, working with a coalescence-induced water removal mechanism. A shield, accounting for the atmospheric radiative heat, facilitates daytime atmospheric water harvesting under solar irradiation at realistic levels of relative humidity. The remarkable cooling power enhancement enables dew mass fluxes up to 50 g m−2 hour−1, close to the ultimate capabilities of such systems. The results demonstrate that the yield of related technologies can be at least doubled, while cooling and collection remain passive, […]
Meringue-like material could make aircraft as quiet as a hairdryer
Pys.org June 18, 2021 Researchers in the UK have developed an ultralight graphene oxide (GO)/polyvinyl alcohol (PVA) aerogel (GPA) with hierarchical and tunable porosity embedded in a honeycomb scaffold. The aerogels have an enhanced ability to dissipate sound energy, with an extremely low density of 2.10 kg m−3. They experimentally evaluated and optimised the effects of composition and thickness on sound absorption, and sound transmission losses. Then employed a semi-analytical approach to evaluate the effect of different processing times on acoustic properties and assessed the relationships between the acoustic and non-acoustic properties of the materials. Over the 400–2500 Hz range, […]
Ocean Microbes May Actually Help Moderate Earth’s Temperature, Scientists Say
Science Alert June 18, 2021 As marine methane seeps, vast quantities of methane move through the shallow subseafloor, where it is largely consumed by microbial communities. A team of researchers in the US (Harvard University, DOE, USGS, UCLA, Caltech) conducted a continental-scale survey of seven geologically diverse seafloor seeps and found that carbonate rocks from all sites host methane-oxidizing microbial communities with substantial methanotrophic potential. In laboratory-based mesocosm incubations, chimney-like carbonates from the coast of Southern California exhibited the highest rates of anaerobic methane oxidation measured to date. After a thorough analysis of physicochemical, electrical, and biological factors, they attributed […]
Outstanding organic solar cells’ performance achieved by using new technology
EurekAlert June 23, 2021 Although the organic photovoltaic (OPV) elements are lighter, more flexible, and cheaper to produce, their efficiency still falls behind that of other photovoltaic technologies. An international team of researchers (Saudi Arabia, Lithuania, Greece) synthesised a material, which self-assembles into a monolayer that can cover a variety of surfaces and function as a hole-transporting layer in a solar element. They made some modifications in the material used in self-assembling molecular-thin layer (SAM) formation to tailor it for organic solar elements. The organic solar cell using Br-2PACz molecule-thin coating as a hole-transporting layer achieved a power conversion efficiency […]
Perovskite memory devices with ultra-fast switching speed
Science Daily June 22, 2021 Halide perovskite-based memory devices have limitations of slow switching speed which hinder their practical application in memory devices. Researchers in South Korea have successfully developed ultra-fast switching memory devices using halide perovskites by using a combined method of first-principles calculations and experimental verification. From a total of 696 compounds of halide perovskites candidates, Cs3Sb2I9 with a dimer structure was selected as the best candidate for memory application. They fabricated memory devices using the dimer-structured Cs3Sb2I9 to verify the calculation results. The devices were operated with an ultra-fast switching speed of 20 ns, which was more […]