Search results for "protonic"

Random Quasi-Phae-Matching in Tantalatio di Litio: origine del fenomeno, confronto tra propagazione bulk e guidata.

2011

We observe second harmonic generation via random quasi phase matching in a 1.5μm periodically poled lithium tantalate. The presence of a slab waveguides allows the comparison between bulk and guided wave configurations.

IPOMAGNESEMIA GRAVE CORRELATA ALL’ASSUNZIONE DI INIBITORE DI POMPA PROTONICA

2017

Gli inibitori di pompa protonica (IPP) sono tra i farmaci più frequentemente assunti nella popolazione anziana, spesso cronicamente, anche per indicazioni non sempre giustificate. Sebbene siano farmaci ben tollerati, emergono sempre nuove e frequenti reazioni avverse. In particolare, negli ultimi anni, sono stati riportati vari case-report di ipomagnesemia insorta dopo terapia prolungata con IPP. Tuttavia, ad oggi, non è stato di-mostrato il meccanismo fisiopatologico con cui queste molecole possono indurre tale disionia. Il magnesio è il secondo catione più abbondante nella cellula e svolge ruoli chiave in molti processi intracellulari. La sua omeostasi è garantita dall’equilibrio tra l’as…

X-ray Spectroscopy of (Ba,Sr,La)(Fe,Zn,Y)O3-δIdentifies Structural and Electronic Features Favoring Proton Uptake

2020

Mixed protonic–electronic conducting oxides are key functional materials for protonic ceramic fuel cells. Here, (Ba,Sr,La)(Fe,Zn,Y)O3−δ perovskites are comprehensively investigated by X-ray spectroscopy (in oxidized and reduced states). Extended X-ray absorption fine structure shows that Zn,Y doping strongly increases the tendency for Fe–O–Fe buckling. X-ray absorption near-edge spectroscopy at the Fe K-edge and X-ray Raman scattering at the O K edge demonstrate that both iron and oxygen states are involved when the samples are oxidized, and for the Zn,Y doped materials, the hole transfer from iron to oxygen is less pronounced. This can be correlated with the observation that these material…

Y:BaZrO3 Perovskite Compounds I: DFT Study on the Unprotonated and Protonated Local Structures

2011

Y-doped BaZrO(3) derivatives were studied by density functional theory (DFT) to investigate the local arrangements of the octahedral sites in Pm3m cubic frameworks. Single- and double substitution of zirconium by yttrium were considered, including in the presence of a nearby oxygen vacancy. Although the structural symmetry of undoped barium zirconate was not modified after yttrium doping, the presence of yttrium induced several differences in the oxygen sites around it, according to the local geometrical arrangement of yttrium in the host matrix. As an example, the differences between such oxygen sites were shown in the presence of a proton. In this case, different stabilization energies ch…

Nuovi conduttori protonici per applicazioni elettrochimiche: sintesi e correlazione struttura-proprietà.

2011

Impedance spectroscopy characterization of functionalized alumina membranes

2005

Abstract Anodic alumina membranes have been impregnated with a protonic conductor either by immersion or by vacuum permeation of a saturated aqueous solution of CsHSO4 for different times. Synthetized salt, obtained through the reaction of cesium carbonate with sulphuric acid (in excess), contained a small quantity of Cs2SO4. Unmodified membranes consist of amorphous Al2O3 with a regular distribution of pores (average diameter: 200 nm) and are stable up to 850 °C. Long impregnation times caused partial dissolution of alumina, with formation of Al(HSO4)3 on the front surfaces as well as into pore walls. From the frequency dispersion of the impedance, the “macroscopic conductivity” of membran…

Computational Studies of the Structure and of the Proton Transport Phenomena in Systems Derived from Barium Cerate Perovskite Structure

2007

The final task of the whole research project is the design of new ceramic materials for protonic conduction in the range of temperature 350-750 °C. To this aim, it was planned to deepen the information on the systems obtained by doping the Ce site in the BaCeO3 perovskite matrices. In these compounds, cerium has been substituted by trivalent elements (Y, In), thus creating – to fulfill charge neutrality – oxygen vacancies that could be filled by hydroxyls groups. In this way protons have been introduced in the structure. These materials are currently investigated by both experimental and computational approaches to integrate framework structure and proton transport phenomena analyses. Due t…