BRILLOUIN SCATTERING IN LIQUID CRYSTALS

On détermine ici le spectre Brillouin du MBBA dans sa phase isotrope. On n'observe aucune dispersion au point de transition.The Brillouin spectrum of the isotropic phase of MBBA was investigated. No dispersion was found at the transition point

Transpiration of the \u2018Rebula\u2019 cuttings (Vitis vinifera L.) grafted on three different rootstocks (Vitis sp.)

The purpose of the investigation was to determine the use of water in grafted vines (Vitis vinifera L.) in dependence on the vine (Vitis sp.) rootstocks. The local vine variety "Rebula' was grafted on three different rootstocks (Vitis sp.): (1) on the 'Rebula' (Vitis vinifera L.) vine itself, (2) on the rootstock 196/17 Castel'[(Vitis vinifera 'Mourv\ue8dre' x Vitis rupestris '1202 Couderc') x Vitis riparia 'Gloire'] and (3) on the rootstock 'B\uf6rner' (Vitis riparia x Vitis cinerea). Daily transpiration was calculated as a difference in the pot mass between the day of measurement and the previous day. Daily differences in the use of water were compared with leaf area and meteorological data (temperature, duration of sun light). Stem water potential (SWP) and, at the end of the trial, leaf area and mass of individual parts of plant (roots, shoot) were determined using destructive method. The dynamics of water used per leaf area unit showed the trend of reduction and the response to the changing meteorological conditions. No statistically significant differences in SWP, leaf area and water used were noticed between rootstocks, however, they existed in the final mass of shoot and roots

Recent achievements in development of TiO2_2-based composite photocatalytic materials for solar driven water purification and water splitting

Clean water and the increased use of renewable energy are considered to be two of the main goals in the effort to achieve a sustainable living environment. The fulfillment of these goals may include the use of solar-driven photocatalytic processes that are found to be quite effective in water purification, as well as hydrogen generation. H$_2$ production by water splitting and photocatalytic degradation of organic pollutants in water both rely on the formation of electron/hole (e$^−$/h$^+$) pairs at a semiconducting material upon its excitation by light with sufficient photon energy. Most of the photocatalytic studies involve the use of TiO$_2$ and well-suited model compounds, either as sacrificial agents or pollutants. However, the wider application of this technology requires the harvesting of a broader spectrum of solar irradiation and the suppression of the recombination of photogenerated charge carriers. These limitations can be overcome by the use of different strategies, among which the focus is put on the creation of heterojunctions with another narrow bandgap semiconductor, which can provide high response in the visible light region. In this review paper, we report the most recent advances in the application of TiO$_2$ based heterojunction (semiconductor-semiconductor) composites for photocatalytic water treatment and water splitting. This review article is subdivided into two major parts, namely Photocatalytic water treatment and Photocatalytic water splitting, to give a thorough examination of all achieved progress. The first part provides an overview on photocatalytic degradation mechanism principles, followed by the most recent applications for photocatalytic degradation and mineralization of contaminants of emerging concern (CEC), such as pharmaceuticals and pesticides with a critical insight into removal mechanism, while the second part focuses on fabrication of TiO$_2$-based heterojunctions with carbon-based materials, transition metal oxides, transition metal chalcogenides, and multiple composites that were made of three or more semiconductor materials for photocatalytic water splitting