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International audience; Water, being the universal solvent, acts as a competing agent in fundamental processes, such as folding, aggregation or biomolecular recognition. A molecular understanding of hydrophobic hydration is of central importance to understanding the subtle free energy differences, which dictate function. Ab initio and classical molecular dynamics simulations yield two distinct hydration water populations in the hydration shell of solvated tert-butanol noted as “HB-wrap” and “HB-hydration2bulk”. The experimentally observed hydration water spectrum can be dissected into two modes, centered at 164 and 195 cm–1. By comparison to the simulations, these two bands are attributed to the “HB-wrap” and “HB-hydration2bulk” populations, respectively. We derive a quantitative correlation between the population in each of these two local water coordination motifs and the temperature dependence of the solvation entropy. The crossover from entropy to enthalpy dominated solvation at elevated temperatures, as predicted by theory and observed experimentally, can be rationalized in terms of the distinct temperature stability and thermodynamic signatures of “HB-wrap” and “HB-hydration2bulk”.

This study aimed to evaluate the efficacy of low-tech augmentative and alternative communication (AAC) aids in improving quality of life (QoL) and mood disorders, as well as the psychosocial impact of assistive devices, in 10 patients affected by amyotrophic lateral sclerosis (ALS) in the early stage of the disease, when speech difficulties appear. The AACtraining (AAC-T) study lasted around six months and comprised two phases of three months each: AAC-intervention (AAC-I) followed by AAC-familiarization (AAC-F). All the patients were assessed at the beginning (T0) and at the end (T1) of AAC-I, as well as at the end of AAC-F (T2). During the AAC-I phase, we applied a three-phase AAC intervention model to evaluate intelligibility of language, participation patterns, communication needs and adaptation to the AAC tools. All the patients showed a gradual and significant improvement, especially in acceptance of the AAC aids, mood and QoL. Moreover, a reduction of caregiver burden was noted. Our study has demonstrated the utility of the AAC aids also in the early stages of the disease in patients with ALS presenting with dysarthria. In our opinion, AAC-T may act as a bridge between the initial and later phases of the disease, when patients need to use high-tech aids, including an eye-tracking communication device. In conclusion, in this study we highlighted how early AAC-T in patients with ALS may be a valuable tool to demonstrate how specific strategies and low-technology aids can improve QoL of these patients and their caregivers, also decreasing stress and depression.

The microscopic dynamics for the gel and liquid-crystalline phase of highly aligned D2O-hydrated bilayers of 1-palmitoyl-oleoyl-sn-glycero-phosphocholine (POPC) were investigated in the temperature range from 248 to 273 K by using incoherent quasi-elastic neutrons scattering (QENS). We develop a model for describing the molecular motions of the liquid phase occurring in the 0.3 to 350 ps time range. Accordingly, the complex dynamics of hydrogen are described in terms of simple dynamical processes involving different parts of the phospholipid chain. The analysis of the data evidences the existence of three different motions: the fast motion of hydrogen vibrating around the carbon atoms, the intermediate motion of carbon atoms in the acyl chains, and the slower translational motion of the entire phospholipid molecule. The influence of the temperature on these dynamical processes is investigated. In particular, by going from gel to liquid-crystalline phase, we reveal an increase of the segmental motion mainly affecting the terminal part of the acyl chains and a change of the diffusional dynamics from a localized rattling-like motion to a confined diffusion.

Molecular dynamics simulations of a coarse-grained, embedded-charge model of lysozyme aqueous solutions are compared with small-angle neutron scattering experiments. Measures concern different solutions with a 10% by weight protein concentration and an increasing pH in the range 2–6. The model is based on a soft-core modification of the original Carlsson–Malmsten–Linse model, where in particular all residues carrying an appreciable amount of residual charge, as a function of the pH, are explicitly taken into account in the overall macromolecular interaction. Simulations reproduce qualitatively the experimental trend of the structure factor such as, in particular, the observed change from a low-pH regime, dominated by repulsive interactions, to behaviour mainly determined by attractive forces, at higher pH. Possible improvements of the model, towards a better reproduction of the structural properties of the real solution, are proposed.

We have investigated the dimyristoylphosphatidylcholine system with a high concentration of butanol (two molecules per phospholipid) via X-ray diffraction, differential scanning calorimetry and density measurements. A lowering of the main transition temperature for the membrane/alcohol system has been observed. The phospholipid bilayer/alcohol system is characterised by a higher density value than the pure membrane, as determined by volumetric measurements. Analysis of diffraction patterns has shown the existence of a more packed structure due to the presence of alcohol. The area of polar head has also been estimated.

The acoustic properties at 10 and 30 MHz of dry and wet boron oxide samples have been investigated over the temperature range between 10 and 300 K. Significant differences in the temperature dependence of acoustic attenuation and longitudinal sound velocity as a function of the annealing treatment and water content have been revealed in the investigated glasses. Measurements, densely performed over the whole temperature range, together with a detailed analysis of the dispersive behaviors, allowed us to evidence the complexity of the relaxational dynamics, as due to the coexistence of different local motions. Above 150 K, the data analysis has been based on the existence of two relaxation processes, whose strengths result to be strictly dependent on the water content. Finally, a possible relation to the empty volume originated from the arrangement of the structural units on nanometer length scale has been put forward.

We investigated molecular motions in the 0.3–350 ps time range of D2O-hydrated bilayers of 1-palmitoyl-oleoyl-sn-glycero-phosphocholine and 1,2-dimyristoyl-sn-glycero-phosphocholine in the liquid phase by quasielastic neutron scattering. Model analysis of sets of spectra covering scale lengths from 4.8 to 30 A revealed the presence of three types of motion taking place on well-separated time scales: (i) slow diffusion of the whole phospholipid molecules in a confined cylindrical region; (ii) conformational motion of the phospholipid chains; and (iii) fast uniaxial rotation of the hydrogen atoms around their carbon atoms. Based on theoretical models for the hydrogen dynamics in phospholipids, the spatial extent of these motions was analysed in detail and the results were compared with existing literature data. The complex dynamics of protons was described in terms of elemental dynamical processes involving different parts of the phospholipid chain on whose motions the hydrogen atoms ride.

By using the fixed energy window method in incoherent elastic neutron scattering, molecular motions in the 150 ps timescale in highly oriented multilayers of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) membranes in excess of water (D2O) have been studied as a function of temperature, in the range from 27 to 325 K. The same system in partially deuterated form and with the addition of a pore-forming peptide (gramicidin) has also been investigated. By proper orientation of the membrane plane with respect to the scattering wavevector Q, information on in plane and out of plane motions of lipid membranes have been derived. Two relevant dynamical transitions were observed at T = 297 K and at T = 270 K. The former is related to the structural main transition from gel to liquid phase of the phospholipid bilayer, while the latter is related to a transition of the aqueous solvent. The inclusion of gramicidin shifts the main transition down to 294 K and the second transition up to 276 K. In both cases the observed dynamical transitions show an enhanced mobility in the direction normal to the membrane plane.