Transport of Canadian forest fire smoke over the UK as observed by lidar

Layers of aerosol at heights between 2 and 11&thinsp;km were observed with Raman lidars in the UK between 23 and 31 May 2016. A network of these lidars, supported by ceilometer observations, is used to map the extent of the aerosol and its optical properties. Space-borne lidar profiles show that the aerosol originated from forest fires over western Canada around 17 May, and indeed the aerosol properties – weak volume depolarisation ( &lt; 5&thinsp;%) and a lidar ratio at 355&thinsp;nm in the range 35–65&thinsp;sr – were consistent with long-range transport of forest fire smoke. The event was unusual in its persistence – the smoke plume was drawn into an atmospheric block that kept it above north-western Europe for 9 days. Lidar observations show how the smoke layers became optically thinner during this period, but the lidar ratio and aerosol depolarisation showed little change. The results demonstrate the value of a dense network of observations for tracking forest fire smoke, and show how the dispersion of smoke in the free troposphere leads to the emergence of discrete thin layers in the far field. They also show how atmospheric blocking can keep a smoke plume in the same geographic area for over a week.</p

Lyotropic Liquid Crystals from Colloidal Suspensions of Graphene Oxide

Lyotropic liquid crystals from colloidal particles have been known for more than a century, but have attracted a revived interest over the last few years. This is due to the developments in nanoscience and nanotechnology, where the liquid crystal order can be exploited to orient and reorient the anisotropic colloids, thus enabling, increasing and switching the preferential properties of the nanoparticles. In particular, carbon-based colloids like carbon nanotubes and graphene/graphene&ndash;oxide have increasingly been studied with respect to their lyotropic liquid crystalline properties over the recent years. We critically review aspects of lyotropic graphene oxide liquid crystal with respect to properties and behavior which seem to be generally established, but also discuss those effects that are largely unfamiliar so far, or as of yet of controversial experimental or theoretical outcome

Transport of Canadian forest fire smoke over the UK as observed by lidar

Abstract. Layers of aerosol at heights between 2 and 11 km were observed with Raman lidars in the UK between 23 and 31 May 2016. A network of such lidars, supported by ceilometer observations, is used to map the extent of the aerosol and its optical properties. Spaceborne lidar profiles show that the aerosol originated from forest fires over Western Canada around 17 May, and indeed the aerosol properties – weak depolarisation and a lidar ratio at 355 nm in the range 35–65 sr – were consistent with long-range transport of forest fire smoke. The event was unusual in its persistence – the smoke plume was drawn into an atmospheric block that kept it above North-west Europe for nine days. Lidar observations show how the smoke layers became optically thinner during this period, but the lidar ratio and aerosol depolarisation showed little change. </jats:p

Stabilization of liquid crystal blue phases by carbon nanoparticles of varying dimensionality

The thermal stabilization of blue phases is a subject that has been of scientific and technological interest since their discovery. Meanwhile, carbonaceous nanomaterials such as C60 fullerenes, carbon nanotubes and graphene have generated interdisciplinary interest spanning across solid-state physics, organic chemistry, colloids, all the way to soft matter physics. Herein, the stabilization of liquid crystal blue phases by doping with C60, single-walled carbon nanotubes and graphene oxide is described. All three types of particles are found to extend the combined temperature range of blue phases I and II by a factor of ∼5. Furthermore, mixtures of pairs of different materials, and all three types are shown to stabilize the blue phases. The temperature range of the blue phases is shown to grow at the expense of the cholesteric phase. This leads to a blue phase-cholesteric-smecticA phase triple-point in all cases except that of doping with carbon nanotubes. The mechanisms of this thermal stabilization are discussed in light of theoretical descriptions for other established systems