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In the research of new nanocomposite proton-conducting membranes, SnO2 ceramic powders with surface functionalization have been synthesized and adopted as additives in Nafion-based polymer systems. Different synthetic routes have been explored to obtain suitable, nanometer-sized sulphated tin oxide particles. Structural and morphological characteristics, as well as surface and bulk properties of the obtained oxide powders, have been determined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) and Raman spectroscopies, N2 adsorption, and thermal gravimetric analysis (TGA). In addition, dynamic mechanical analysis (DMA), atomic force microscopy (AFM), thermal investigations, water uptake (WU) measurements, and ionic exchange capacity (IEC) tests have been used as characterization tools for the nanocomposite membranes. The nature of the tin oxide precursor, as well as the synthesis procedure, were found to play an important role in determining the morphology and the particle size distribution of the ceramic powder, this affecting the effective functionalization of the oxides. The incorporation of such particles, having sulphate groups on their surface, altered some peculiar properties of the resulting composite membrane, such as water content, thermo-mechanical, and morphological characteristics.

Elastin is a cross-linked protein, whose soluble precursor is tropoelastin, responsible for resilience and elastic recoil in vertebrate tissues. Glycine and proline are among the most repeated amino acids in tropoelastin primary structure, the high flexible glycine being present 222 times and the more constrained proline being present 96 times. In order to deeper investigate the role of glycine and proline residues in elastin, we studied the molecular and supramolecular structures of polyglycine and poly-L-proline homopolypeptides as significant sequences for the protein. As a matter of fact, up to now, if few conformational studies are accessible only for poly-L-proline homopolypeptide in solution and for polyglycine homopolypeptide in the solid state, limited supramolecular studies are available for both homopolypeptides. Given the self-aggregation properties of these homopolypeptides, we investigated the aggregation mechanism by turbidimetry measurements together with Congo red birefringence assay, ThT fluorescence spectroscopy, and atomic force microscopy and transmission electron microscopy studies. At molecular level, we show the dominance of the cross-b structure for polyglycine fibrils while for poly-L-proline aggregates PPII conformation prevails. At supramolecular level, the results show that polyglycine is able to self-aggregate into amyloid-like fibres while poly-L-proline aggregates by following a specific pathway ranging from protofibrils to fibrils. These findings suggest that the self-aggregation properties of elastin are influenced by tropoelastin primary structure thus explaining why glycine-rich elastin-derived polypeptide sequences are amyloidogenic (Gly-effect) while proline-rich elastin-derived polypeptide sequences (Pro-effect) are able to coacervate.

We report on the process of lithium intercalation in V 2 O 5 thin films deposited onto standard ITO-coated glass substrates. The films were deposited via a well-established sol-gel route, and the samples were examined as working electrodes in a range of potentials versus lithium reference electrode. This paper follows up issues arising from parallel spectroscopic characterizations of the films by X-ray photoelectron spectroscopy (XPS). Specifically, the XPS examination showed that not all of the Li-ion charge inserted was accounted for by the V(5) to V(4) reduction, but the stoichiometric balance could be maintained only by considering additional oxygens arising from the intercalation procedure, leading to Li 2 O formation. In this work, we have examined the possibility that the source of oxygen is the ITO substrate. To this purpose, films of V 2 O 5 deposited on silicon substrates have been prepared using the sol-gel process and examined by XPS after electrochemical intercalation/de-intercalation cycles. We show that in this case a perfect balance between electrochemical charge, inserted Li and reduced vanadium is obtained. A further indication of ITO-substrate effects was obtained from examination, by the same methods, of some unconventional V 2 O 5 films that had been co-precipitated with a siloxane, designed to provide a template structure. The results obtained from this material imply that a barrier layer is formed at the ITO interface and, therefore, the formation of Li 2 O is avoided. The results are discussed in terms of the possible degradation of conventional V 2 O 5 on ITO as a result of electrochemically induced interface reactions.

The ultrashort pulsed laser deposition of vanadium oxide thin films has been carried out by a frequency-doubled Nd:glass laser with a pulse duration of 250 fs. The characteristics of the plasma produced by the laser−target interaction have been studied by ICCD imaging and optical emission spectroscopy. The results confirm that an emitting plasma produced by ultrashort laser pulses is formed by both a primary and a secondary component. The secondary component consists of particles with a nanometric size, and their composition and spatial angular distribution influence the deposited films. In fact, these films, analyzed by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and atomic force microscopy, are formed by the aggregation of a large number of nanoparticles whose composition is explained by a model based on equilibrium thermal evaporation from particles directly ejected from the target. On these basis, the presence in the films of a mixture of V2O5 and VO2 is discussed.