Science Daily March 17, 2022 Researchers at Columbia University developed a genetically encoded microbial encapsulation system with tunable and dynamic expression of surface capsular polysaccharides that enhances systemic delivery. Based on a small RNA screen of capsular biosynthesis pathways, they constructed inducible synthetic gene circuits that regulate bacterial encapsulation in Escherichia coli Nissle 1917. These bacteria are capable of temporarily evading immune attack, whereas subsequent loss of encapsulation results in effective clearance in vivo. This dynamic delivery strategy enabled a ten-fold increase in maximum tolerated dose of bacteria and improved anti-tumor efficacy in murine models of cancer. In situ encapsulation […]
Ice Cores Reveal Huge Volcanic Eruptions, Bigger Than Anything in The Last 2,500 Years
Science Alert March 20, 2022 Large volcanic eruptions occurring in the last glacial period can be detected by their accompanying sulfuric acid deposition in continuous ice cores. Using such data an international team of researchers (Demark, Switzerland, Italy, UK, Canada) estimated the emission strength, frequency and the climatic forcing of large volcanic eruptions that occurred during the second half of the last glacial period and the early Holocene epoch. Due to limited data resolution and large variability in the sulfate background signal, they identified 1113 volcanic eruptions in Greenland and 737 eruptions in Antarctica within the 51 kyr period. They found […]
Light derails electrons through graphene (w/video)
Nanowerk March 24, 2022 An international team of researchers (Spain, USA – Columbia University, Japan, Singapore) showed that by applying circular polarized infrared light onto the bilayer graphene device, they could selectively excite one specific valley population of electrons in the material, which generated a photovoltage perpendicular to the usual electron flow. By engineering the device and setup in such a way that current only flows with light illumination, they were able to avoid the background noise that hampers measurements and achieved a sensitivity in the detection several orders of magnitude better than any other 2D material. They could control […]
Novel quantum sensing possibilities with nonlinear optics of diamonds
Phys.org March 22, 2022 Taking advantage of the properties, especially the harmonic generation of nitrogen vacancy in diamond researchers Japan have presented an efficient and viable way for creating diamond-based nonlinear optical temperature sensing. Using infrared ultrashort pulse laser stimulation, the team found that the harmonic generation decreased with temperature over the range of 20–300°C. The temperature-dependent change was explained by mismatch due to the speed of different colors of light in the diamond. As the atomic lattice heats up, the difference in the index of refraction between the original light and the higher energy light created by harmonic generation […]
Photonic encryption platform in the ultraviolet and visible
Science Daily March 17, 2022 Researchers in South Korea have developed an optical encryption platform that works simultaneously in the visible and ultraviolet (UV) regimes. They adjusted the physical properties of silicon nitride to reduce its tendency to absorb ultraviolet light. They fabricated a metahologram in which an image clearly appears when ultraviolet laser is irradiated on it. They combined the two metaholograms that work in the ultraviolet and visible light regions to create an anticounterfeiting device that displays a unique product number. The hologram that appears when a visible light laser is irradiated acts as a key and when […]
Physicists create compressible optical quantum gas
Phys.org March 24, 2022 The compressibility of a medium, quantifying its response to mechanical perturbations is a fundamental property determined by the equation of state. For gases of material particles studies of the mechanical response are well established in fields from classical thermodynamics to cold atomic quantum gases. Researchers in Germany demonstrated the measurement of the compressibility of a two-dimensional quantum gas of light in a box potential and obtained the equation of state for the optical medium. The experiment was carried out in a nanostructured dye-filled optical microcavity. They observed signatures of Bose-Einstein condensation at high phase-space densities in […]
Qubits: Developing long-distance quantum telecommunications networks
Science Daily March 22, 2022 An international team of researchers (Switzerland, France) has stored a qubit for 20 milliseconds in crystals doped with europium capable of absorbing light and then re-emitting it. They managed to reach the 100-millisecond mark with a small loss of fidelity. The crystals were kept at -273,15°C, because beyond 10°C above this temperature, the thermal agitation of the crystal destroys the entanglement of the atoms. In theory, it would be enough to increase the duration of exposure of the crystal to radio frequencies, but for the time being, technical obstacles to their implementation over a longer […]
Researchers develop silicon cuboid nanoantenna
Phys.org March 21, 2022 The Purcell effect is commonly used to increase the spontaneous emission rate by modifying the local environment of a light emitter. Researchers in China studied the scattering cross section, polarization charge distribution, and electromagnetic field distribution for electromagnetic plane wave illuminating the silicon dielectric cuboid nanoantenna and identified simultaneous existence of electric dipole (ED), magnetic dipole (MD) and electric quadrupole (EQ) emission resonance modes in this nanoantenna. When they calculated the Purcell factor of ED, MD, and EQ emitters with different moment orientations as a function of radiation wavelength by placing these point radiation source within […]
Researchers develop the world’s first power-free frequency tuner using nanomaterials
Science Daily March 18, 2022 Phase-change materials (PCMs) can switch between amorphous and crystalline states permanently yet reversibly. However, the change in their mechanical properties has largely gone unexploited. The most practical configuration using suspended thin-films suffer from filamentation and melt-quenching. An international team of researchers (UK, USA – University of Pennsylvania) used nanowires as active nanoelectromechanical systems (NEMS) to overcome these limitations. They achieved active modulation of the Young’s modulus in GeTe nanowires by exploiting a unique dislocation-based route for amorphization. The nanowire NEMS enable power-free tuning of the resonance frequency over a range of 30% and their high […]
Single-photon source paves the way for practical quantum encryption
Phys.org March 23, 2022 Researchers in Australia have developed an on-demand way to generate photons with high purity in a scalable and portable system that operates at room temperature. They combined hexagonal boron nitride with a hemispherical solid immersion lens, which increases the source’s efficiency by a factor of six. They incorporated the single-photon source into a fully portable device that can perform QKD. They demonstrated that it could produce over ten million single photons per second at room temperature. The streamlined device is easier to use and much smaller than traditional optical table setups allowing the system to be […]