Fe/GeTe(111) heterostructures as an avenue towards 'ferroelectric Rashba semiconductors'-based spintronics

By performing density functional theory (DFT) and Green's functions calculations, complemented by X-ray Photoemission Spectroscopy, we investigate the electronic structure of Fe/GeTe(111), a prototypical ferromagnetic/Rashba-ferroelectric interface. We reveal that such system exhibits several intriguing properties resulting from the complex interplay of exchange interaction, electric polarization and spin-orbit coupling. Despite a rather strong interfacial hybridization between Fe and GeTe bands, resulting in a complete suppression of the surface states of the latter, the bulk Rashba bands are hardly altered by the ferromagnetic overlayer. This could have a deep impact on spin dependent phenomena observed at this interface, such as spin-to-charge interconversion, which are likely to involve bulk rather than surface Rashba states.Comment: 8 pages, 4 figure

Mechanical lifting energy consumption in work activities designed by means of the "revised NIOSH lifting equation"\u80\u9d

The aims of the present work were: to calculate lifting energy consumption (LEC) in work activities designed to have a growing lifting index (LI) by means of revised NIOSH lifting equation; to evaluate the relationship between LEC and forces at the L5-S1 joint. The kinematic and kinetic data of 20 workers were recorded during the execution of lifting tasks in three conditions. We computed kinetic, potential and mechanical energy and the corresponding LEC by considering three different centers of mass of: 1) the load (CoML); 2) the multi-segment upper body model and load together (CoMUpp+L); 3) the whole body and load together (CoMTot). We also estimated compression and shear forces. Results shows that LEC calculated for CoMUpp+L and CoMTot grew significantly with the LI and that all the lifting condition pairs are discriminated. The correlation analysis highlighted a relationship between LEC and forces that determine injuries at the L5-S1 joint

UV Treatment of the Stabilizing Shell for Improving the Photostability of Silver Nanoparticles

Silver nanoparticles or nanoclusters are quite sensitive to light exposure. In particular, irradiation in the localized surface plasmon resonance (LSPR) region brings about a drastic modification of their optical properties due to growth and reshaping of the nanoparticles. In order to obtain luminescent colloids, small silver colloidal nanoparticles were prepared in chloroform using vinylpyrrolidone oligomers as capping agent and their luminescence properties were used to control their stability upon prolonged exposure to visible light. The polymeric shell around the metal clusters was hardened through photo-cross-linking by UV light. This process did not alter the morphology and the optical properties of the nanoparticles but greatly improved the particle photostability as confirmed also by confocal laser scanning microscopy measurements. The data clearly show that UV curing of the stabilizing layer could be a simple postsynthetic procedure to obtain materials with stable properties

Una proposta didattica sulla teoria della relativita ristretta: un approccio geometrico

All’interno di questa tesi di laurea magistrale viene elaborata una proposta didattica sulla teoria della relatività ristretta a partire da un approccio geometrico. Si vedrà che i motivi che giustificano questo tipo di approccio, più precisamente storico-geometrico, sono da ricercarsi nel legame epistemologico esistente tra matematica e fisica. Si osserverà poi come la storia possa fungere da ponte tra le due discipline e si individueranno i temi chiave dell’integrazione della storia nell’insegnamento della matematica e della fisica. Si proporrà quindi una breve contestualizzazione storica del periodo per poi elaborare la proposta didattica vera e propria. Essa si propone come un’alternativa all’usuale approccio fisico che parte dalle trasformazioni di Lorentz (1904) e dai due postulati della relatività ristretta di Einstein (1905), approfondendo il punto di vista dei matematici dei primi anni del 1900. Prendendo spunto da una rivisitazione in chiave didattica dei lavori di H.A. Lorentz, J.H. Poincaré e H. Minkowski si partirà dalla struttura di gruppo delle trasformazioni tra sistemi inerziali (J.H. Poincaré 1904) per arrivare al concetto di spazio-tempo e alle trasformazioni che lasciano invariato il cono di luce (H. Minkowski 1908). In conclusione vengono osservati gli effetti relativistici sui diagrammi di Minkowski