MIT News June 15, 2023 Hygroscopic hydrogels are emerging as scalable and low-cost sorbents for atmospheric water harvesting, dehumidification, passive cooling, and thermal energy storage. However, devices using these materials still exhibit insufficient performance, partly due to the limited water vapor uptake of the hydrogels. Researchers in Germany synthesized hygroscopic hydrogels with extremely high salt loadings by tuning the salt concentration of the swelling solutions and the cross-linking properties of the gels. This resulted in unprecedented water uptakes at relative humidity. At 30% RH, the uptake exceeded previously reported water uptakes of metal–organic frameworks by over 100% and of hydrogels […]
Tag Archives: S&T Germany
Trillionths of a second: Photon pairs compress an electron beam into short pulses
Phys.org June 19, 2023 Researchers in Germany used nonlinear-optical two-photon transitions for the quantum-coherent control of a free-electron matter wave in free space. They superimposed an electron beam with two crossed laser beams of different photon energies for non-linear Compton scattering. At suitable angle combinations, the electron energy spectrum became modulated into discrete energy sidebands with thousands of interference maxima. They explained their observations by the cascaded addition and subtraction of two-photon pairs under three-body conservation of energy and momentum. Calculations revealed that the electron matter wave converted into pulses of few-attosecond duration. According to the researchers their work provides […]
New technology developed for quantum cryptography applications
Phys.org May 10, 2023 Temporal modes (TMs), an encoding basis based on the time-frequency degree of freedom of photons, represent one of the most promising high-dimensional alphabets. TM-based quantum communication has until now been limited to a two-dimensional space due to the lack of a suitable decoder. However, quantum communication protocols based on single-photon TMs require suitable multichannel decoders. Researchers in Germany have demonstrated a new device that facilitates demultiplexing of high-dimensional TMs of single photons, and implemented a complete five-dimensional decoder that enables TM-based high-dimensional quantum key distribution. They showed that it is possible to scale the presented decoder […]
Researchers demonstrate high natural radioactivity of manganese nodules
Phys.org May 17, 2023 In search for critical elements, polymetallic nodules at the deep abyssal seafloor are targeted for mining operations. Nodules efficiently scavenge and retain several naturally occurring uranium-series radioisotopes, which predominantly emit alpha radiation during decay. Researchers in Germany have presented new data on the activity concentrations of thorium-230, radium-226, and protactinium-231, as well as on the release of radon-222 in and from nodules from the NE Pacific Ocean. They demonstrated that the activity concentrations for several alpha emitters were often higher than at the surface of the nodules. The observed values could exceed current exemption levels by […]
Magnetic bacteria: Microorganisms can help to extract dangerous heavy metals from wastewater
Phys.org May 8, 2023 Researchers in Germany purified water containing uranium using a special kind of bacteria known as magnetotactic bacteria which can accumulate dissolved heavy metal in their cell walls. The bacteria form nanoscopic magnetic crystals within the cell which are arranged like a row of beads. Each individual magnetic crystal is embedded in a protective membrane. The crystals and membrane form the magnetosome which the bacteria use to align themselves with the Earth’s magnetic field and orientate themselves in their habitat. It also makes them suitable for simple separation processes. The cell walls of magnetotactic bacteria are surrounded […]
Laser light hybrids control giant currents at ultrafast times
Phys.org April 13, 2023 Spin and valley indices represent the key quantum labels of quasi-particles in a wide class of two-dimensional materials and form the foundational elements of the fields of spintronics and valleytronics. Researchers in Germany have discovered a route to induce and control the flow of spin and valley currents at ultrafast times with specially designed laser pulses, offering a new perspective on the ongoing search for the next generation of information technologies. They showed that femtosecond laser light combining optical frequency circularly polarized pulse and a terahertz (THz) frequency linearly polarized pulse can generate precisely tailored and […]
Researchers develop novel nonwovens that are electrically conductive but thermally insulating
Phys.org April 4, 2023 Materials with an extremely low thermal and high electrical conductivity that are easy to process, foldable, and nonflammable are required for sustainable applications, notably in energy converters, miniaturized electronics, and high-temperature fuel cells. Given the inherent correlation between high thermal and high electrical conductivity, innovative design concepts that decouple phonon and electron transport are necessary. Researchers in Germany achieved a unique combination of thermal conductivity and electrical conductivity in electrospun nonwovens comprising carbon as the matrix and silicon-based ceramics as nano-sized inclusions with a sea-island nanostructure. The carbon phase modulates electronic transport for high electrical conductivity, […]
Stalactites and stalagmites in the battery?
Science Daily March 17, 2023 The role of grain boundaries in the nucleation and dendritic growth of metallic lithium is not yet fully understood. Researchers in Germany used operando Kelvin probe force microscopy measurements to map locally time-dependent electric potential changes in the Li6.25Al0.25La3Zr2O12 garnet-type solid electrolyte. They found that the Galvani potential dropped at grain boundaries near the lithium metal electrode during plating as a response to the preferential accumulation of electrons. Time-resolved electrostatic force microscopy measurements and quantitative analyses of lithium metal formed at the grain boundaries under electron beam irradiation supported this finding. Based on these results, […]
A dozen exotic bacteria are found to passively collect rare earth elements from wastewater
Phys.org February 28, 2023 Biosorption of metal ions by phototrophic microorganisms is regarded as a sustainable and alternative method for bioremediation and metal recovery. Researchers in Germany optimized the conditions of rare earth elements (REE) uptake by the cyanobacterial biomass and characterized the most important chemical mechanisms for binding them. They found the highest absorption capacity of lanthanum, cerium, neodymium, and terbium by 12 strains of cyanobacteria in laboratory culture. Biosorption depended strongly on acidity: it was highest at a pH of between five and six and decreased steadily in more acid solutions. They could adsorb amounts of REEs corresponding […]
Wafer-scale nanofabrication of telecom single-photon emitters in silicon
Phys.org February 23, 2023 Monolithic integration of single-photon sources in a controllable way would give a resource-efficient route to implement millions of photonic qubits in photon integrated circuits. To run quantum computation protocols, these photons must be indistinguishable. Building on their previous work researchers in Germany have shown how focused ion beams from liquid metal alloy ion sources are used to place single-photon emitters at desired positions on the wafer while obtaining a high creation yield and high spectral quality. After several cooling-down and warming-up cycles, there was no degradation of their optical properties. To allow for wafer-scale engineering of […]