Method for Tuneable Homeotropic Anchoring at Microstructures in Liquid Crystal Devices

A simple method for vapour-phase deposition of a silane surfactant is presented, which produces tuneable homeotropic anchoring in liquid crystals. Both the zenithal anchoring energy and surface slip are measured by fitting to the latching threshold versus pulse width characteristic of a zenithal bistable nematic liquid crystal device based on a deep, submicron grating. The method is shown to give microscopic anchoring strength between 5 × 10⁻⁵ and 2 × 10⁻⁴ J/m², with a surface slip of about 100 nm. The silanated surfaces are characterized using atomic force microscopy and X-ray photoelectron spectroscopy, which show a direct relationship between the surface coverage of silane groups and the resulting anchoring energy

Activity of chemolithotrophic nitrifying bacteria under stress in natural soils

Nitrification is an important process in the biogeochemical cycle of nitrogen, linking its reduced and oxidized parts. Since the conversion of ammonium to nitrate has a great impact on the environment, such as weathering of soils, production of greenhouse gases, and eutrophication of surface and ground waters, it is important to know the characteristics of the responsible organisms. Although many organotrophic microorganisms are able to produce oxidized nitrogenous compounds such as nitrite and nitrate, chemolithotrophic nitrifying bacteria are considered to be the most important group producing these compounds from ammonia. A contribution to nitrate production by organotrophic microorganisms has only been observed in some acid coniferous forest soils

Review of recent experimental and modeling advances in the understanding of lower hybrid current drive in ITER-relevant regimes

Progress in understanding lower hybrid current drive (LHCD) at high density has been made through experiments and modeling, which is encouraging given the need for an efficient off-axis current profile control technique in burning plasma. By reducing the wall recycling of neutrals, the edge temperature is increased and the effect of parametric instability (PI) and collisional absorption (CA) is reduced, which is beneficial for increasing the current drive efficiency. Strong single pass absorption is preferred to prevent CA and high LH operating frequency is essential for wave propagation to the core region at high density, presumably to mitigate the effect of PI. The dimensionless parameter that characterizes LH wave accessibility and wave refraction for the experiments in this joint study is shown to bracket the region in parameter space where ITER LHCD experiments will operate in the steady state scenario phase. Further joint experiments and cross modeling are necessary to understand the LHCD physics in weak damping regimes which would increase confidence in predictions for ITER where the absorption is expected to be strong