Phys.org November 22, 2021 Geoengineering using sulfuric acid would happen in the stratosphere. The major inputs for the creation of sulfuric acid are sulfur dioxide, hydroxyl radicals which create hydroxysulfonyl radical (HOSO2). This in turn reacts with oxygen to create sulfur trioxide (SO3) which results in sulfuric acid when it reacts with water. Aerosols formed from the sulfuric acid can reflect sunlight. These reactions create acid rain in the troposphere. If the same chemistry would work in the stratosphere is unknown. An international team of researchers (USA -University of Pennsylvania, Spain) has shown that the photodissociation of HOSO2 occurs primarily […]
By keeping ferroelectric ‘bubbles’ intact, researchers pave way for new devices
Phys.org November 19, 2021 Bubble-like domains, typically a precursor to the electrical skyrmions, arise in ultrathin complex oxide ferroelectric–dielectric–ferroelectric heterostructures epitaxially clamped with flat substrates. An international team of researchers (USA – Argonne National Laboratory, University of Arkansas, University of Chicago, Australia) peeled off heterostructure thin films containing electrical bubbles from the substrate, while keeping them fully intact. To establish that the bubble domains remained intact, they measured the capacitance and piezoelectric properties and found they stayed relatively stable up to a high voltage. The combination of experiment and simulation proved conclusively that these bubbles can live even when removed […]
Doing photon upconversion a solid – Crystals that convert light to more useful wavelengths
Nanowerk November 25, 2021 A promising way to realize photon upconversion (PUC) is through triplet-triplet annihilation (TTA). Researchers in Japan discovered that ANNP, a hydrocarbon molecule originally developed for blue organic LEDs, was an excellent annihilator. They mixed it with platinum octaethylporphyrin (PtOEP), a staple sensitizer that absorbs green light. They demonstrated substantial advantages of the van der Waals solid solution concept to yield molecular crystals with extraordinary performance. A 0.001%-order porphyrin sensitizer is dissolved during recrystallization into the molecular crystals of a blue-fluorescent hydrocarbon annihilator, 9-(2-naphthyl)-10-[4-(1-naphthyl)phenyl]anthracene (ANNP). The solid crystals they produced were highly stable and exhibited outstanding performance. […]
An exploration of tipping in complex systems
Phys.org November 23, 2021 In this review article an international team of researcher (India, Germany, Russia) explored the nature of tipping in complex systems presented in 21 articles and presented them in three broad areas: in the first part, they focus on the mechanisms that can induce tipping between different states; the second group of papers explores the measures that characterize tipping phenomena, and suggests strategies that could be used to control them, and the final part presents several specific case studies of tipping in complex systems, such as traffic flows, precipitation patterns, and dust cloud instabilities. They conclude with […]
How sugar-loving microbes could help power future cars
Phys.org November 22, 2021 A team of researchers in the US (UC Berkeley, University of Minnesota) has harnessed biology and chemistry to turn glucose into olefins. They genetically engineered E. coli to produce a suite of four enzymes that convert glucose into compounds called 3-hydroxy fatty acids. As the bacteria consumed the glucose, they also started to make the fatty acids. To complete the transformation, they used niobium pentoxide (Nb2O5) a catalyst to chop off unwanted parts of the fatty acids in a chemical process, generating the final product: the olefins. According to the team more research is needed to […]
Iodine successfully tested in satellite ion thrusters
Phys.org November 18, 2021 Xenon is used almost exclusively as an ionizable propellant for space propulsion. However, xenon is rare, it must be stored under high pressure and production cost is high. Researchers in France used iodine propellant in a system and presented in-orbit results of the technology. They stored iodine as a solid and sublimated at low temperatures. Plasma was produced with a radio-frequency inductive antenna with enhanced ionization efficiency. Both atomic and molecular iodine ions were accelerated by high-voltage grids to generate thrust, and a highly collimated beam was produced with substantial iodine dissociation. The propulsion system was […]
Magnetic symmetry is not just like looking in a mirror (w/video)
Nanowerk November 18, 2021 Magnetizing RAM technology could reduce energy consumption. To do so domain walls must be better understood. An international team of researchers (USA – UC San Diego, Carnegie Mellon University, University of Colorado, France) uncovered the quantitative explanation for magnetic symmetry breaking during domain wall motion based on experiments performed using thin films of platinum, cobalt, and nickel. By applying magnetic fields in various directions to Pt/Co/Ni they saw that instead of growing in a direction parallel to the magnetic field the domains jetted out along precise, but seemingly arbitrary directions, which appeared to violate conventional notions […]
New device modulates visible light—without dimming it—with the smallest footprint and lowest power consumption
Phys.org November 22, 2021 Currently, the two most suitable materials are silicon nitride and lithium niobate. While both are highly transparent in the visible range, neither one provides very much tunability. A team of researchers in the US (Columbia University, Tufts University) developed a way to dramatically reduce both the size and the power consumption of a visible-spectrum phase modulator, from 1 mm to 10 microns and from tens of mW for π phase tuning to below 1 mW. The key to their solution was to use an optical resonator and to operate it in the strongly over-coupled regime. In […]
New ultrahard diamond glass synthesized
Phys.org November 24, 2021 An international team of researchers (China, USA – Carnegie Institution for Science, Germany, Sweden) has synthesized millimetre-sized samples of transparent, nearly pure sp3 amorphous carbon by heating fullerenes at pressures close to the cage collapse boundary. The material synthesized consists of many randomly oriented clusters with diamond-like short-/medium-range order and possesses the highest hardness, elastic modulus and thermal conductivity observed in any known amorphous material. It also exhibits optical bandgaps tunable from 1.85 eV to 2.79 eV. The ultrahard form of carbon glass with a wealth of potential practical applications for devices and electronics. The use of new […]
Researchers fabricate complex optical components from fluids
Nanowerk November 18, 2021 Based on controlling the minimum energy state of the interface between a curable optical liquid and an immersion liquid and dictating a geometrical boundary constraint a team of researchers in Israel has developed a method to shape liquid volumes and solidify them into desired freeform components. They provided an analytical solution for the resulting topography given a predefined boundary and demonstrated the fabrication of freeform components with sub-nanometer surface roughness within minutes. The process allows for rapid prototyping of high-quality components, has the potential to answer an unmet need in the optical design industry and allowing […]