Cultural landscapes of the XXI century: world heritage and local responsibility

Reikšminiai žodžiai: Kultūriniai kraštovaizdžiai; Kuršių nerija; Pasaulinis paveldas; UNESCO; Vietinių žmonių atsakomybė; Vietos gyventojai; XXI a. kultūriniai kraštovaizdžiai; And Local Responsibility; Cultural Landscapes; Cultural Landscapes of the XXI Century; Curonian Spit; Local dwellers; UNESCO; World Heritag

On Protein Preferential Solvation in Water:Glycerol Mixtures

For proteins in solvent mixtures, the relative abundances of each solvent in their solvation shell have a critical impact on their properties. Preferential solvation of a series of proteins in water-glycerol mixtures is studied here over a broad range of solvent compositions via classical molecular dynamics simulations. Our simulation results reveal that the differences between shell and bulk compositions exhibit dramatic changes with solvent composition, temperature and protein nature. In contrast with the simple and widely used picture where glycerol is completely excluded from the protein interface, we show that for aqueous solutions with less than 50% glycerol in volume, protein solvation shells have approximately the same composition as the bulk solvent and proteins are in direct contact with glycerol. We further demonstrate that at high glycerol concentration, glycerol depletion from the solvation shell is largely due to an entropic factor arising from the reduced accessibility of bulky glycerol molecules in protein cavities. The resulting molecular picture is important to understand protein activity and cryopreservation in mixed aqueous solvents.<br /

Enzyme-like reactivity for increasing selectivity in CO2 electrochemical reduction

The development of selective catalysts for the reduction of CO2 mostly focuses on electrocatalytic approaches and aims at increasing the selectivity of the reaction while keeping a high activity, which is difficult to achieve. Metalloporphyrins are good catalysts for CO2 reduction because they have favorable electronic properties and offer the possibility to make use of secondary coordination sphere effects. Here, we present a new approach to CO2 reduction, which is based on host-guest chemistry enabled by an iron porphyrin cage catalyst. When this iron porphyrin cage catalyst is immobilized on a conducting carbon support the selectivity for CO2 reduction to CO stays above 90 % in a wide range of overpotentials. The hosting of potassium ions in the cage of the catalyst decreases the overpotential of the reduction and increases the catalytical activity while retaining the high selectivity. DFT calculations show that the potassium ions assist the reduction of CO2 by making the 2-electron transfer from iron(0) to CO2 exothermic. Upon protonation, the Fe-COOH intermediates have been trapped by combining an electrochemical cell with an electrospray ionization mass spectrometer and their structure has been characterized by cryogenic ion spectroscopy

Crystallization of 2D Hybrid Organic–Inorganic Perovskites Templated by Conductive Substrates

2D hybrid organic–inorganic perovskites are valued in optoelectronic applications for their tunable bandgap and excellent moisture and irradiation stability. These properties stem from both the chemical composition and crystallinity of the layer formed. Defects in the lattice, impurities, and crystal grain boundaries generally introduce trap states and surface energy pinning, limiting the ultimate performance of the perovskite; hence, an in-depth understanding of the crystallization process is indispensable. Here, a kinetic and thermodynamic study of 2D perovskite layer crystallization on transparent conductive substrates are provided—fluorine-doped tin oxide and graphene. Due to markedly different surface structure and chemistry, the two substrates interact differently with the perovskite layer. A time-resolved grazing-incidence wide-angle X-ray scattering (GIWAXS) is used to monitor the crystallization on the two substrates. Molecular dynamics simulations are employed to explain the experimental data and to rationalize the perovskite layer formation. The findings assist substrate selection based on the required film morphology, revealing the structural dynamics during the crystallization process, thus helping to tackle the technological challenges of structure formation of 2D perovskites for optoelectronic devices