Top 10 Science and Technology Inventions for the Week of September 29, 2023
01. Imaging the elusive skyrmion: Neutron tomography reveals their shapes and dynamics in bulk materials
02. Light and sound waves reveal negative pressure
03. Material would allow users to ‘tune’ windows to block targeted wavelengths of light
04. Nanofluidic device generates power with saltwater
05. Novel approach towards nanomaterials developed
06. One-atom-thick ribbons could improve batteries, solar cells and sensors
07. Researchers advance topological superconductors for quantum computing
08. Researchers fabricate chip-based optical resonators with record low UV losses
09. Single sideband modulation technique can relax the bandwidth restriction
10. Transistor-inspired ultra-sensitive materials heat up advanced data security
And others
Efficient fuel-molecule sieving using graphene
Successful optical biosensing using dual optical combs: High sensitivity and rapid detection of biomolecules
Topological materials open a new pathway for exploring spin hall materials
Towards computational design of molecules with desired properties
Transparent wood-based coating doesn’t fog up
Efficient fuel-molecule sieving using graphene
Phys.org September 22, 2023
Proton exchange membranes with high proton conductivity and low crossover of fuel molecules are required to realize advanced fuel-cell technology. The selective transportation of protons, which occurs by blocking the transportation of fuel molecules across a proton exchange membrane, is crucial to suppress crossover while maintaining a high proton conductivity. An international team of researchers (Japan, Germany) proposed a simple yet powerful method for optimizing the crossover-conductivity relationship by pasting sulfanilic-functionalized holey graphenes onto a Nafion membrane. Their results showed that the sulfanilic-functionalized holey graphenes supported by the membrane suppressed the crossover by 89% in methanol and 80% in formate compared with that in the self-assembled Nafion membrane. They observed approximately 60% reduction in the proton conductivity. According to the researchers this method exhibits the potential for application in advanced fuel cells that use methanol and formic acid as chemical fuels to achieve high energy efficiency… read more. Open Access TECHNICAL ARTICLE
Imaging the elusive skyrmion: Neutron tomography reveals their shapes and dynamics in bulk materials
Phys.org September 26, 2023
Commonly observed in thin systems as two-dimensional sheets, in three dimensions skyrmions form tubes that are thought to nucleate and annihilate along their depth on points of vanishing magnetization. However, a lack of techniques that can probe the bulk of the material has made it difficult to perform experimental visualizations of skyrmion lattices and their stabilization through defects. An international team of researchers ( Canada, USA – NIST, SUNY Buffalo, Germany) provided three-dimensional visualizations of a bulk Co8Zn8Mn4 skyrmion lattice through a tomographic algorithm applied to multiprojection small-angle neutron scattering measurements. Reconstructions of the sample showed a disordered skyrmion lattice exhibiting three-dimensional topological transitions through emergent (anti) monopole branching and segmentation defect pathways. According to the researchers their technique provides insights into skyrmion stabilization and topological transition pathways in a bulk skyrmion lattice, guiding the future development and manipulation of skyrmion materials for spintronic applications… read more. Open Access TECHNICAL ARTICLE
Light and sound waves reveal negative pressure
Phys.org September 25, 2023
Pressure is encountered in various fields – atmospheric pressure in meteorology, blood pressure in medicine, etc. Examining the physical properties of materials under a wide range of thermodynamic states is a challenging problem due to the extreme conditions the material must experience. Such temperature and pressure regimes, which result in a change in the refractive index and sound velocity, can be accessed by optoacoustic interactions such as Brillouin–Mandelstam scattering. An international team of researchers (Germany, France, Australia) demonstrated the Brillouin–Mandelstam measurements of nanolitre volumes of liquids in extreme thermodynamic regimes enabled by a fully sealed liquid-core optical fibre containing carbon disulfide. Within this waveguide, which exhibited tight optoacoustic confinement and a high Brillouin gain, they were able to conduct spatially resolved measurements of the local Brillouin response, which gave access to a resolved image of the temperature and pressure values along the liquid channel. They measured the material properties of the liquid core at very large positive pressures (above 1,000 bar) and substantial negative pressures (below –300 bar), as well as explored the isobaric and isochoric regimes. The extensive thermodynamic control allowed the tunability of the Brillouin frequency shift of more than 40% using only minute volumes of liquid… read more. Open Access TECHNICAL ARTICLE
Material would allow users to ‘tune’ windows to block targeted wavelengths of light
Phys.org September 26, 2023
Dual-band electrochromism, the independent modulation of visible and near-infrared light by a single material, is highly desirable for smart windows to enhance the energy efficiency of buildings. Tungsten oxides are commercially important electrochromic materials, exhibiting reversible visible and near-infrared absorption when electrochemically reduced in an electrolyte containing small cations or protons. The presence of structural water in tungsten oxides has been associated with faster electrochromic switching speeds. A team of researchers in the US (North Carolina State University, UT Austin, Vanderbilt University) found that WO3·H2O, a crystalline hydrate, exhibited dual-band electrochromism unlike the anhydrous WO3. Making use of this property they tuned the electrochromic response of tungsten oxides demonstrated absorption of near-infrared light at low Li+/e– injection, followed by the absorption of visible light at higher Li+/e– injection because of an electrochemically induced phase transition. The dual-band modulation was possible due to the more open structure of WO3·H2O compared to WO3, which facilitated a more extended solid-solution Li+ insertion regime that benefited the modulation of near-infrared radiation via plasmon absorption. Higher degrees of Li+/e– insertion led to polaronic absorption associated with localized charge storage. According to the researchers their results show how structural factors influence the electrochemically induced spectral response of transition-metal oxides and the important role of structural water beyond optical switching speed… read more. TECHNICAL ARTICLE
Nanofluidic device generates power with saltwater
Nanowerk September 23, 2023
Researchers at the University of Illinois designed a nanofluidic device capable of converting ionic flow into usable electric power. Combining computational and analytical approach based on Green’s function technique and Boltzmann transport formalism they established the onset of electronic current in a doped silicon membrane induced by the long-range Coulomb interaction of ions flowing through a nanofluidic channel. Characterized by an open circuit voltage and short circuit current, the electronic Coulomb drag provided a new paradigm for power harvesting. Their model predicted a current amplification of the ionic drag current because of the large momentum transfer from heavy ions to charge carriers in silicon, which was achieved for both anions and cations flowing in the nanochannel irrespective of the dopant type in the semiconductor. The analysis indicated the versatility of this effect with respect to the nature of the electrolyte and the semiconducting materials, provided proper tuning of their structures and design configurations… read more. TECHNICAL ARTICLE
Novel approach towards nanomaterials developed
Nanowerk September 25, 2023
In a typical approach for creating nanostructures ligands are grafted onto the surfaces of nanoparticles to improve the dispersion stability and control interparticle interactions. Ligands remain secondary and usually are not expected to order significantly during superstructure formation. Researchers in Germany investigated how ligands can play a more decisive role in the formation of anisotropic inorganic–organic hybrid materials. They grafted poly(2-iso-propyl-2-oxazoline) (PiPrOx) as a crystallizable shell onto SiO2 nanoparticles. By varying the PiPrOx grafting density, both solution stability and nanoparticle aggregation behavior could be controlled. Upon prolonged heating, anisotropic nanostructures formed in conjunction with the crystallization of the ligands. Self-assembly of hybrid PiPrOx@SiO2 (shell@core) nanoparticles first, formed amorphous aggregates via gelation, mediated by the interaction between nanoparticles through grafted polymer chains. As a second step, slow radial growth of fibers was observed via directional crystallization, governed by the incorporation of crystalline ribbons formed from free polymeric ligands in combination with crystallization of the covalently attached ligand shell. According to the researchers their work revealed how crystallization-driven self-assembly of ligands can create intricate hybrid nanostructures… read more. TECHNICAL ARTICLE
One-atom-thick ribbons could improve batteries, solar cells and sensors
Science Daily September 21, 2023
Quasi-1D nanoribbons provide a unique route to diversifying the properties of their parent 2D nanomaterial, introducing lateral quantum confinement and an abundance of edge sites. Phosphorus-only materials do not conduct electricity very well, hindering their use for certain applications. Researchers in the UK created a new family of nanomaterials with the creation of arsenic–phosphorus alloy nanoribbons (AsPNRs). By ionically etching the layered crystal black arsenic–phosphorus using lithium electride followed by dissolution in amidic solvents, solutions of AsPNRs were formed. The ribbons were typically few-layered, several micrometers long with widths tens of nanometers across, and both highly flexible and crystalline. The AsPNRs were highly electrically conducting above 130 K due to their small band gap (ca. 0.035 eV), paramagnetic in nature, and had high hole mobilities, as measured with the first generation of AsP devices, directly highlighting their properties and utility in electronic devices such as near-infrared detectors, quantum computing, and charge carrier layers in solar cells… read more. Open Access TECHNICAL ARTICLE
Researchers advance topological superconductors for quantum computing
Nanowerk September 21, 2023
The interface between 2D topological Dirac states and an s-wave superconductor is expected to support Majorana-bound states (MBS) that can be used for quantum computing applications. Realizing these novel states of matter and their applications requires control over superconductivity and spin-orbit coupling to achieve spin-momentum-locked topological interface states (TIS) which are simultaneously superconducting. A team of researchers in the US (Oak Ridge National Laboratory, Rutgers State University of New Jersey) have shown superconductivity in monolayer (ML) FeTe1–ySey (Fe(Te,Se)) grown on Bi2Te3 by molecular beam epitaxy (MBE). Spin and angle-resolved photoemission spectroscopy (SARPES) directly resolved the interfacial spin and electronic structure of Fe(Te,Se)/Bi2Te3 heterostructures. For y = 0.25, the electronic structure was found to overlap with the Bi2Te3 TIS and the desired spin-momentum locking was not observed. In contrast, for y = 0.1, reduced inhomogeneity measured by scanning tunneling microscopy and a smaller Fe(Te,Se) Fermi surface with clear spin-momentum locking in the topological states were found. The researchers have demonstrated that the Fe(Te,Se)/Bi2Te3 system is a highly tunable platform for realizing MBS where reduced doping can improve characteristics important for Majorana interrogation and potential applications… read more. TECHNICAL ARTICLE
Researchers fabricate chip-based optical resonators with record low UV losses
Phys.org September 26, 2023
UV and visible photonics enable applications ranging from spectroscopic sensing to communication and quantum information processing. Photonics structures in these wavelength regimes tend to experience higher loss than their IR counterpart. Particularly in the near-UV band, on-chip optical microresonators have not yet achieved a quality factor beyond 1 million. A team of researchers in the US (Yale University, industry) developed ultra-low-loss photonic waveguides and resonators patterned from alumina thin films prepared by a highly scalable atomic layer deposition process. They demonstrated ultra-high Q factor of 1.5×106 at 390 nm, a record value at UV bands, and 1.9×106 at 488.5 nm… read more. Open Access TECHNICAL ARTICLE