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Dimethyl sulfoxide (DMSO) is a universal water-soluble solvent widely used in many biotechnological and medical applications, such as cells cryopreservation, and for the treatment of different human diseases (e.g. amyloidosis). Despite the great number of reported studies, the effects of DMSO on the physico-chemical properties of biological membranes are poorly understood. Often, these studies are limited to model membranes composed of phosphatidylcholines (PCs) and cholesterol (Chol). In this work, we explored the effect of DMSO on liposomes composed of the natural egg sphingomyelin (ESM) and Chol as raft-like model membranes. With a multi-technique approach we probe the structure and the thermal stability of ESM/Chol bilayer at different Chol mole fractions. In particular, we investigate the ESM-solvent interactions to clarify the role of DMSO in perturbing the solvating conditions of lipid vesicles and show that the addition of DMSO increases the thermal stability of vesicles. An increase of transition temperature, a decrease of both enthalpy and entropy as well as a decrease of the cooperativity of the gel to liquid phase transition are observed at 0.1 DMSO mole fraction. Fluorescence experiments with the probe Laurdan and FTIR spectra strongly indicate that DMSO exerts a dehydration effect on the membrane. Besides, FTIR measurements with tungsten hexacarbonyl, in combination with fluorescence data of the probe NBD-PE, indicate that DMSO promotes the formation of a highly packed membrane by reducing the thickness of the membrane., (Copyright © 2019 Elsevier B.V. All rights reserved.)

High-resolution vacuum ultraviolet photoabsorption measurements in the wavelength range of 115-320 nm (10.8-3.9 eV) have been performed together with comprehensive relativistic time-dependent density functional calculations (TDDFT) on the low-lying excited sates of tungsten hexacarbonyl, W(CO) 6 . The higher resolution obtained reveals previously unresolved spectral features of W(CO) 6 . The spectrum shows two higher-energy bands (in the energy ranges of 7.22-8.12 eV and 8.15-9.05 eV), one of them with clear vibrational structure, and a few lower-energy shoulders in addition to a couple of lower-energy metal-to-ligand charge-transfer (MLCT) bands reported in the literature before. Absolute photoabsorption cross sections are reported and, where possible, compared to previously published results. On the basis of this combined experimental/theoretical study the absorption spectrum of the complex has been totally re-assigned between 3.9 and 10.8 eV under the light of spin-orbit coupling (SOC) effects. The present comprehensive knowledge of the nature of the electronically excited states may be of relevance to estimate neutral dissociation cross sections of W(CO) 6 , a precursor molecule in focused electron beam induced deposition (FEBID) processes, from electron scattering measurements.

We present the results of our study about the deposition rate of focused electron beam induced processing (FEBIP) as a function of the substrate temperature with the substrate being an electron-transparent amorphous carbon membrane. When W(CO)6 is used as a precursor it is observed that the growth rate is lower at higher substrate temperatures. From Arrhenius plots we calculated the activation energy for desorption, E des, of W(CO)6. We found an average value for E des of 20.3 kJ or 0.21 eV, which is 2.5-3.0 times lower than literature values. This difference between estimates for E des from FEBIP experiments compared to literature values is consistent with earlier findings by other authors. The discrepancy is attributed to electron-stimulated desorption, which is known to occur during electron irradiation. The data suggest that, of the W(CO)6 molecules that are affected by the electron irradiation, the majority desorbs from the surface rather than dissociates to contribute to the deposit. It is important to take this into account during FEBIP experiments, for instance when determining fundamental process parameters such as the activation energy for desorption.