Phys.org December 20, 2024 Although porous structures should favor colonization by microorganisms, they have not yet been exploited as abiotic scaffolds for the development of living materials. Researchers in Switzerland developed porous ceramics that are colonized by bacteria to form an engineered living material with self-regulated and genetically programmable carbon capture and gas-sensing functionalities. The carbon capture capability was achieved using wild-type photosynthetic cyanobacteria, whereas the gas-sensing function was generated utilizing genetically engineered E. coli. Hierarchical porous clay was used as a ceramic scaffold and evaluated in terms of bacterial growth, water uptake, and mechanical properties. Using state-of-the-art chemical analysis […]
Category Archives: Materials science
Machine learning speeds up prediction of materials’ spectral properties
Phys.org December 23, 2024 Koopmans spectral functionals enable the prediction of spectral properties with state-of-the-art accuracy which relies on capturing the effects of electronic screening through scalar, orbital-dependent parameters. The parameters must be computed for every calculation, making Koopmans spectral functionals more expensive. Researchers in Switzerland developed a machine-learning model that can predict these screening parameters directly from orbital densities calculated at the density-functional theory (DFT) level. In two cases they showed that using the screening parameters predicted by this mode led to orbital energies that differ by less than 20 meV on average. This approach substantially reduced the run time […]
Scientists develop material with almost perfect water repellency
Phys.org December 12, 2024 While the accessible pores render an enormous variety of functionalities to the bulk of metal–organic frameworks (MOFs), the outer surfaces exposed by these crystalline materials also offer unique characteristics not available when using conventional substrates. An international team of researchers (Germany, India) fabricated superhydrophobic substrates with static water contact angles over 160° by grafting hydrocarbon chains to well-defined MOF thin films (SURMOFs) prepared using layer-by-layer methods. A detailed theoretical modelling of the hydrocarbon chains grafted on the outer SURMOF surface with well-defined spacing between anchoring points revealed that the grafted hydrocarbon chains behaved similarly to polymer […]
Tiny particle, huge potential: Scientists discover new type of quasiparticle present in all magnetic materials
Phys.org December 17, 2024 When the geometrical size of a nanomagnetic system is constricted to the limiting domain wall length scale, the competing energetics between anisotropy, exchange, and dipolar interactions can cause emergent kinetics due to quasiparticle relaxation, like bulk magnets of atomic origin. A team of researchers in the US (Columbia University, Oak Ridge National Laboratory) conducted an experimental and theoretical study to support that constricted nanomagnets, made of antiferromagnetic and paramagnetic neodymium thin film with honeycomb motif, revealed fast kinetic events at picosecond timescales due to the relaxation of topological quasiparticles that persisted to low temperature in the […]
Cooperative motion by atoms protects glass from fracturing
Phys.org December 2, 2024 The slow β, or Johari–Goldstein (JG) relaxation process, has been widely observed in glasses and is known to induce the stress relaxation associated with mechanical properties. So far, jumping motions of only a fraction of the particles were believed to contribute to the JG process in glass. However, there is no direct experimental evidence of the atomic-scale images due to the difficulties in microscopic observation. Researchers in Japan observed atomic motions in the quasi-spherical model ionic-glass-former calcium potassium nitrate. The experiment directly indicated that most particles underwent angstrom-scale motions in the time scale of the JG […]
MIT physicists predict exotic form of matter with potential for quantum computing
MIT News November 18, 2024 Based on the recent discovery of fractional quantum anomalous Hall states in moiré systems, researchers at MIT studied a family of moiré systems, skyrmion Chern band models, which could be realized in two-dimensional semiconductor-magnet heterostructures and capture the essence of twisted transition metal dichalcogenide homobilayers. Using many-body exact diagonalization they showed that, despite strong Berry curvature variations in momentum space, the non-Abelian Moore-Read state could be realized at half filling of the second miniband. According to the researchers, their results demonstrate the feasibility of non-Abelian fractionalization in moiré systems without Landau levels and shed light […]
Fluids thicken at the speed of light: A new theory extends Einstein’s relativity to real fluids
Phys.org November 7, 2024 Researchers in Germany derived a general theory of the viscosity of gases based on the relativistic Langevin equation and nonaffine linear response theory. The proposed relativistic theory was able to recover the viscosity of nonrelativistic classical gases, with all its key dependencies on mass, temperature, particle diameter, and Boltzmann constant, in the limit of Lorentz factor =1. It also unveiled the relativistic enhancement mechanism of viscosity. According to the researchers in the limit of ultra relativistic fluids, the theory provides an analytical formula which reproduces the cubic increase of viscosity with temperature in agreement with various […]
Scientists unlock mechanisms of liquid-repellent surfaces
Phys.org November 11, 2024 Understanding and controlling liquid interactions on tiny, advanced surfaces, a breakthrough that could impact a wide range of industries, from self-cleaning materials to medical devices. Through experimental approaches and theoretical analysis, a team of researchers in Australia assessed how variations in geometry and material impact wettability. Key findings revealed that SiC re-entrant structures had similar hydrophobic behavior. Although flat SiC surfaces exhibited higher inherent hydrophobicity than flat SiO₂, re-entrant geometry predominantly influenced wetting behavior. Structures with lower solid area fractions showed increased hydrophobicity, with a distinct hierarchy: micro lines were the least hydrophobic, followed by shark-skin […]
Successful development of a perfect diamagnetic conducting polymer
Phys.org October 28, 2024 Researchers in Japan synthesized Fe-doped polyaniline (D-PANI) in which they observed diamagnetism at T < 24 K under a weak external magnetic field. D-PANI was air-stable and showed the Peierls transition, as its resistivity increased rapidly at low temperatures, behaving as an electromagnetic insulator. It showed high sensitivity to magnetic fields, with its diamagnetic character changing under a relatively low magnetic field at 4 K. Its resistivity remained almost constant at high temperatures, and the nearest neighbor electron hopping conduction. Polarons in D-PANI showed perfect diamagnetism at low temperatures. After purification, D-PANI contained C, N, O, […]
Discovery challenges existing theories of magnetism in kagome metals
Phys.org October 30, 2024 The rare earth RMn6Sn6 (R = rare earth) family magnetic kagome systems, where their kagome flat bands are calculated to be near the Fermi level in the paramagnetic phase have been reported. While partially filling a kagome flat band is predicted to give rise to a Stoner-type ferromagnetism, experimental visualization of the magnetic splitting across the ordering temperature has not been reported for any of these systems leaving the nature of magnetism in kagome magnets an open question. An international team of researchers (USA – Rice University, Brookhaven National Lab, Los Alamos National Laboratory, Israel, Czech Republic) probed […]