Chasing the cuprates with dilatonic dyons

Magnetic field and momentum dissipation are key ingredients in describing condensed matter systems. We include them in gauge/gravity and systematically explore the bottom-up panorama of holographic IR effective field theories based on bulk Einstein-Maxwell Lagrangians plus scalars. The class of solutions here examined appear insufficient to capture the phenomenology of charge transport in the cuprates. We analyze in particular the temperature scaling of the resistivity and of the Hall angle. Keeping an open attitude, we illustrate weak and strong points of the approach.Comment: 30 pages, 2 figures, Version to appear in JHE

Chalcogen bonds in selenocysteine seleninic acid, a functional GPx constituent, and in other seleninic or sulfinic acid derivatives

The controlled oxidation reaction of L-selenocystine under neutral pH conditions affords selenocysteine seleninic acid (3-selenino-L-alanine) which is characterized also by means of single-crystal X-ray diffraction. This technique shows that selenium forms three chalcogen bonds (ChBs), one of them being outstandingly short. A survey of seleninic acid derivatives in the Cambridge Structural Database (CSD) confirms that the C−Se(=O)O− functionality tends to act as a ChB donor robust enough to systematically influence the interactional landscape in the solid. Quantum Theory of Atom in Molecules (QTAIM) analysis proves the attractive nature of the short contacts observed in crystals containing the seleninic functionality and calculation of surface molecular electrostatic potential (MEP) reveals that remarkably positive σ-holes can frequently be found opposite to the covalent bonds at selenium. Both CSD searches and QTAIM and MEP approaches show that also the sulfinic acid moiety can function as a ChB donor, albeit less frequently than the seleninic acid one. These findings may contribute to a better understanding, at the atomic level, of the mechanism of action of the enzymes that control oxidative stress and ROS deactivation and that contain selenocysteine seleninic acid and cysteine sulfinic acid in the active site

Metallurgical and mechanical characterization of the historical tie-rod of Duomo di Milano

Tie-rods have an important structural role in most of the vaulted constructions due to their capacity to balance the horizontal thrusts. However, their reliability in ancient buildings is often impaired by the manufacturing technology and the incidence of defects. One paradigmatic example is represented by Duomo di Milano, whose hand forged elements date back to the first half of the 15th century and have been the object of the metallurgical characterization herein presented. The occasion arose from the replacement of a deeply fractured tie-rod, two cross-sections of which were analyzed in details: one close to the breaking surface and the breaking surface itself. The investigations carried out on the first sample were aimed to characterize the material, while those performed on the second one were finalized to estimate the causes of the failure. Stereoscopy, light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and Vickers hardness tests were employed to analyze the local chemical composition, microstructure and mechanical properties of the material. A good agreement among the results of these analyses was found. The insight into the quality of this wrought iron is of remarkable significance as concerns the representativeness of laboratory mechanical tests and the potential of diagnostic techniques for in-situ inspection