Successful 54 Gbit/s on–off keying (OOK) transmission over 2.2 km of multimode OM4 fibre is demonstrated. The decisive advantages of the single mode over multimode vertical cavity surface emitting ...laser (VCSEL) in transmission experiments are shown.
Porous polymeric beads have been used as templates for the fabrication of porous metal oxide spheres. The beads were soaked in sols of titanium dioxide, zirconium dioxide, iron oxide, aluminum oxide, ...indium oxide, tin oxide, and cerium oxide. Successful infiltration and templating was obtained for titania, zirconia, tin oxide, and ceria giving monodisperse, nonaggregated spheres with a porous surface and inner structure. The use of iron and aluminum oxide sols resulted in cracked spheres with excess oxide material on the sphere surfaces, and in the case of indium oxide, broken, hollow, shell-like structures were produced. Combining the iron, aluminum, or indium oxide sols with the titania sol, at a 1:1 weight ratio, and impregnating the template produced inorganic spheres containing the two metal oxides. The photocatalytic properties of the titania and mixed titania/indium oxide spheres were studied by monitoring the decomposition of 2-chlorophenol as a function of time and solution pH. Both the porous titania and mixed titania/indium oxide spheres were more efficient photocatalysts than Degussa P25 titania, a commercial standard. Optimum solution pH for the photocatalytic reaction was determined to be pH 6 for the titania spheres and pH 4 for the titania/indium oxide sample. Pyridine adsorption on the mixed titanium/indium oxide spheres showed FTIR peak shifts similar to those of the indium oxide spheres, which indicated the presence of stronger Lewis acid sites compared with the titania spheres.
•Ultrasound accelerates synthesis of nanofibrillar cellulose/polystyrene composite.•High biodegradability of nanofibrillar cellulose/polystyrene composite.•High mechanic strength of nanofibrillar ...cellulose/polystyrene composite.
A new method of the synthesis of nanofibrillar cellulose/polystyrene composite based on ultrasonic treatment of styrene emulsion in cellulose-water solution was elaborated. A new approach does not require additional heating and proposes a significantly faster synthesis (15 min, 45 °C) of the target composite compared to the methods described previously. A comprehensive analysis did not reveal any significant differences between mechanical, physical and biodegradable properties of the composite obtained by ultrasonic method and that one obtained by conventional thermal method, which requires much higher temperature (above 75 °C) and reaction duration (from 3 h).
A powder of uniform high entropy alloy AlCoCrFeNi was produced by relatively short-term (90 min) mechanical alloying in a planetary mill followed by annealing at 873, 1073 and 1273 K for 5.5 h. ...Results of high-temperature in situ XRD analyses demonstrated the occurrence of specific crystal lattice transformations taking place in major fcc and bcc phases during annealing and cooling down. Shrinkage of atomic structures was detected for all phases after annealing at any temperature, while precipitation of the σ-phase occurred only at 1073 K. A drift of the (111) peak relative to the (200) peak of the fcc phase at 1273 K allowed us to assume the occurrence of weak martensitic transformations: a high-temperature cubic phase turns into slightly tetragonal phase (a/c = 1.00426) upon cooling down to room temperature. This transformation takes place without mechanical stress or deformation. Despite structural transformations, the major high-entropy phases remained after annealing.
•Equiatomic CoCrFeNiAl alloy was produced by a quick (90 min) mechanical synthesis.•Annealing converts as-synthesized disordered phase into distinct fcc and bcc phases.•Shrinkage of crystal structure up to 0.7% occurs due to annealing at 873–1273 K.•High-temperature in situ XRD reveals cubic-tetragonal transformation in fcc phase.•The fcc and bcc high-entropy phases persist in alloy after 5.5 h of heat treatment.
A new microcontainer for DNA delivery based on biocompatible polyβ-glucuronic acid-(1 → 3)-N-acetyl-β-galactosamine-6-sulfate-(1 → 4)(chondroitin sulfate)/poly(-l-arginine) microcapsules with 40 nm ...thick molecularly organized shell was proposed. DNA molecules were deposited as DNA/sperimidine complex on the surface of template 4 μm core particles followed by layer-by-layer nanoassembly of protective chondroitin sulfate/poly(-l-arginine) shell. After template core dissolution, DNA molecules were captured inside microcapsules retaining a natural double-helix structure. The developed DNA encapsulation approach can be employed for targeted delivery of plasmid DNA in living cells.
Phase change materials (PCMs) store latent heat energy as they melt and release it upon freezing. However, they suffer from chemical instability and poor thermal conductivity, which can be improved ...by encapsulation. Here, we encapsulated a salt hydrate PCM (Mg(NO3)2·6H2O) within all-silica nanocapsules using a Pickering emulsion template. Electron microscopy analysis demonstrated robust silica–silica (RSS) shell formed inner silica layer of approximately 45 nm thickness, with silica Pickering emulsifiers anchored to the surface. The RSS nanostructured capsules are 300–1000 nm in size and have far superior thermal and chemical stability compared with that of the bulk salt hydrate. Differential scanning calorimetry showed encapsulated PCMs were stable over 500+ melt/freeze cycles (equivalent to 500+ day/night temperature difference) with a latent heat of 112.8 J·g–1. Thermogravimetric analysis displayed their impressive thermal stability, with as little as 37.2% mass loss at 800 °C. Raman spectroscopy proved the presence of salt hydrate within RSS capsules and illustrated the improved chemical stability compared to non-encapsulated Mg(NO3)2·6H2O. Energy capsule behavior compared with the bulk material was also observed at the macroscale with thermal imaging, showing that the melting/freezing behavior of the PCM is confined to the nanocapsule core. The thermal conductivity of the silica shell measured by laser flash thermal conductivity method is 1.4 ± 0.2 W·(m·K)−1, which is around 7 times more than the thermal conductivity of the polymer shell (0.2 W·(m·K)−1). RSS capsules containing PCMs have improved thermal stability and conductivity compared to polymer-based capsules and have good potential for thermoregulation or energy storage applications.
High-entropy alloy CoCrFeNiMn was produced by short high energy ball milling (90 min) and spark plasma sintering (10 min at 1073 K). Co-existence of two fcc-phases with lattice parameters 0.360 nm ...and 0.356 nm was demonstrated via HRTEM, XRD and other methods. The matrix fcc-phase with larger parameter transforms into the more compact phase during annealing up to 1273 K. Similar transformation partially occurs after SPS. Some elements, mostly Cr and Mn, released from the matrix phase and formed precipitates. Up to three types of precipitates, with characteristic size from 10-30 nm to 200–300 nm, have been detected and studied. Electric and thermal properties of the material, measured at room and elevated temperature, shown that lattice thermal conductivity plays an important role, along with free electron thermal conductivity.
Display omitted
•CoCrFeNiMn produced by 90 min of high energy ball milling and consolidated by SPS.•Two fcc-phases present in the alloy with lattice parameters 0.360 and 0.356 nm.•The loose fcc-phase transforms into more compact phase when annealing up to 1273 K.•Cr and Mn release from the fcc-matrix phase forming precipitates 10-30 and 200–300 nm.•Electric and thermal conductivities are measured at room and elevated temperature.
•A system with three-body forces in strong confinement is investigated by means of molecular dynamics simulation. The crystal structure of this system at different densities is studied.
Crystal ...structure of the Stillinger-Weber system in a narrow slit pore is studied. It is discovered that depending on the density the system forms several different crystal phases. Importantly, the system splits into several layers, and the symmetry of different layers can be different, which is not observed in systems with pair interaction only.
We present a novel method for remote release of an encapsulated material from polyelectrolyte capsules based on laser light illumination. Two different components were introduced in the ...polyelectrolyte shells of PAH/PSS capsuleseither Ag nanoparticles or IR dyeto induce absorption of light. Under laser illumination the capsules containing Ag nanoparticles or IR dye were deformed or cut, thus providing a venue for remote release of encapsulated materials. The experiments were conducted with a low-power near-infrared continuous-wave laser diode.
PDF
