LSb(μ‐I)2(μ‐S)SbL: a Neutral Triply Bridged Complex obtained from Sb Powder and Diiodine activated by Tetraphenyldithioimidodiphosphine (HL)

The synthesis of the complex LSb(μ‐I)₂(μ‐S)SbL ( 1 ) was accomplished by reacting antimony powder with diiodine activated by tetraphenyldithioimidodiphosphine (SPPh₂NHPPh₂S) (H L ). X‐ray diffraction (tetragonal, M = 1426.30, space group I 4₁/a (No. 88), Z = 8, a = 18.020(2) Å, c = 33.037(4) Å) shows that ( 1 ) is a dinuclear Sb^III complex, in which the two metal ions are bridged by one sulphide and two iodide anions. An anionic bidentate L ligand completes the coordination sphere of each metal with its two sulphur atoms, leading to a slightly distorted pyramidal coordination geometry, since each metal ion shows the presence of a sterically active lone‐pair in trans position to the bridging sulphide. ³¹P CP‐MAS NMR and IR spectroscopies are in accordance with the structural features of the complex.     

Vibrational Energy Transfer in CO+N2 Collisions: A Database for V–V and V–T/R Quantum-Classical Rate Coefficients

Knowledge of energy exchange rate constants in inelastic collisions is critically required for accurate characterization and simulation of several processes in gaseous environments, including planetary atmospheres, plasma, combustion, etc. Determination of these rate constants requires accurate potential energy surfaces (PESs) that describe in detail the full interaction region space and the use of collision dynamics methods capable of including the most relevant quantum effects. In this work, we produce an extensive collection of vibration-to-vibration (V–V) and vibration-to-translation/rotation (V–T/R) energy transfer rate coefficients for collisions between CO and N2 molecules using a mixed quantum-classical method and a recently introduced (A. Lombardi, F. Pirani, M. Bartolomei, C. Coletti, and A. Laganà, Frontiers in chemistry, 7, 309 (2019)) analytical PES, critically revised to improve its performance against ab initio and experimental data of different sources. The present database gives a good agreement with available experimental values of V–V rate coefficients and covers an unprecedented number of transitions and a wide range of temperatures. Furthermore, this is the first database of V–T/R rate coefficients for the title collisions. These processes are shown to often be the most probable ones at high temperatures and/or for highly excited molecules, such conditions being relevant in the modeling of hypersonic flows, plasma, and aerospace applications.     

Enriching the Finite Element Method with meshfree techniques in structural mechanics

The automatic generation of meshes for the Finite Element method can be an expensive computational burden, especially in structural problems with localized stress peaks. The use of meshless methods can address such an issue, as these techniques do not require the existence of an underlying connection among the nodes selected in a general domain. However, a thoroughly meshfree technique can be computationally quite expensive. Usually, the most expensive tasks rely on identifying the nodal contacts and computing the Galerkin integrals. In this thesis we advance a novel hybrid technique that blends Finite Elements with the Meshless Local Petrov-Galerkin method with the aim at exploiting the most attractive properties of each procedure. The idea relies on the use of the Finite Element Method to compute a background solution that is locally improved by enriching the approximating space with the basis functions associated to a few meshless nodes, thus taking advantage of the flexibility ensured by the use of particles disconnected from an underlying grid. Adding the meshless particles only where needed avoids the cost of mesh refining, or even of re-meshing, without the prohibitive burden of a thoroughly meshfree approach. In particular, two enriching methods are introduced and discussed, with applications in structural mechanics. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Analysis of a viscous soft dielectric elastomer generator operating in an electrical circuit

Dielectric Elastomer Generators (DEGs) are able to convert mechanical work into electric energy. A soft dielectric elastomer generator can be modelled as a strain-dependent variable capacitor undergoing large viscoelastic deformation. In this work we analyze an electrical circuit for energy harvesting in which the DEG is stretched periodically by a source of mechanical work. Since these devices undergo a high number of electro-mechanical loading cycles at large deformation, it turns out that viscous effects must be carefully taken into account as they strongly affect the generator performance. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Alternative Fast and Slow Primary Charge-Separation Pathways in Photosystem II

Photosystem-II (PSII) is a multi-subunit protein complex that harvests sunlight to perform oxygenic photosynthesis. Initial light-activated charge separation takes place at a reaction centre consisting of four chlorophylls and two pheophytins. Understanding the processes following light excitation remains elusive due to spectral congestion, the ultrafast nature, and multi-component behaviour of the charge-separation process. Here, using advanced computational multiscale approaches which take into account the large-scale configurational flexibility of the system, we identify two possible primary pathways to radical-pair formation that differ by three orders of magnitude in their kinetics. The fast (short-range) pathway is dominant, but the existence of an alternative slow (long-range) charge-separation pathway hints at the evolution of redundancy that may serve other purposes, adaptive or protective, related to formation of the unique oxidative species that drives water oxidation in PSII.     

Efficient DNA Extraction and Amplification of Samples from the Archeological Site of Pompei (Italy)

Due to their growth and metabolism, microorganisms can cause severe damage to Cultural Heritage, through mechanical and chemical processes. In this paper we used molecular approaches to study bacterial communities on samples from the archeological site of Pompei (Italy). In particular four DNA extraction methods without prior cultivation of the microflora were compared. In terms of efficiency, the DNA extraction method based on the Tri-Reagent™ kit gave the best results. All extraction protocols coupled with 16S rDNA fragments PCR amplification were satisfactory; but the best results were obtained by Klentaq DNA LA Polymerase™; this enzyme can be considered an effective tool for amplification of DNA from Cultural Heritage and possibly other environmental samples.     

Acid-Resistant BODIPY Amino Acids for Peptide-Based Fluorescence Imaging of GPR54 Receptors in Pancreatic Islets

The G protein-coupled kisspeptin receptor (GPR54 or KISS1R) is an important mediator in reproduction, metabolism and cancer biology; however, there are limited fluorescent probes or antibodies for direct imaging of these receptors in cells and intact tissues, which can help to interrogate their multiple biological roles. Herein, we describe the rational design and characterization of a new acid-resistant BODIPY-based amino acid (Trp-BODIPY PLUS), and its implementation for solid-phase synthesis of fluorescent bioactive peptides. Trp-BODIPY PLUS retains the binding capabilities of both short linear and cyclic peptides and displays notable turn-on fluorescence emission upon target binding for wash-free imaging. Finally, we employed Trp-BODIPY PLUS to prepare some of the first fluorogenic kisspeptin-based probes and visualized the expression and localization of GPR54 receptors in human cells and in whole mouse pancreatic islets by fluorescence imaging.     

Birkhoff Normal Form and Long Time Existence for Periodic Gravity Water Waves

We consider the gravity water waves system with a periodic one-dimensional interface in infinite depth and give a rigorous proof of a conjecture of Dyachenko-Zakharov [16] concerning the approximate integrability of these equations. More precisely, we prove a rigorous reduction of the water waves equations to its integrable Birkhoff normal form up to order 4. As a consequence, we also obtain a long-time stability result: periodic perturbations of a flat interface that are initially of size ε remain regular and small up to times of order ${\epsilon }^{-3}$. This time scale is expected to be optimal. © 2022 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC.