Mixed atomistic–implicit quantum/classical approach to molecular nanoplasmonics

A multiscale quantum mechanical (QM)/classical approach is presented that is able to model the optical properties of complex nanostructures composed of a molecular system adsorbed on metal nanoparticles. The latter is described by a combined atomistic-continuum model, where the core is described using the implicit boundary element method (BEM) and the surface retains a fully atomistic picture and is treated employing the frequency-dependent fluctuating charge and fluctuating dipole (ωFQFμ) approach. The integrated QM/ωFQFμ-BEM model is numerically compared with state-of-the-art fully atomistic approaches, and the quality of the continuum/core partition is evaluated. The method is then extended to compute surface-enhanced Raman scattering within a time-dependent density functional theory framework

The Amsterdam Modeling Suite

In this paper, we present the Amsterdam Modeling Suite (AMS), a comprehensive software platform designed to support advanced molecular and materials simulations across a wide range of chemical and physical systems. AMS integrates cutting-edge quantum chemical methods, including Density Functional Theory (DFT) and time-dependent DFT, with molecular mechanics, fluid thermodynamics, machine learning techniques, and more, to enable multi-scale modeling of complex chemical systems. Its design philosophy allows for seamless coupling between components, facilitating simulations that range from small molecules to complex biomolecular and solid-state systems, making it a versatile tool for tackling interdisciplinary challenges, both in industry and in academia. The suite also emphasizes user accessibility, with an intuitive graphical interface, extensive scripting capabilities, and compatibility with high-performance computing environments

Three-dimensional graphene on a nano-porous 4H-silicon carbide backbone: a novel material for food sensing applications

Background: Sensors that are sensitive to volatile organic compounds, and thus able to monitor the conservation state of food, are precious because they work non-destructively and allow avoiding direct contact with the food, ensuring hygienic conditions. In particular, the monitoring of rancidity would solve a widespread issue in food storage. Results: The sensor discussed here is produced utilizing a novel three-dimensional arrangement of graphene, which is grown on a crystalline silicon carbide wafer previously porousified by chemical etching. This approach allows a very high surface-to-volume ratio. Furthermore, the structure of the sensor surface features a large number of edges, dangling bounds, and active sites, which make the sensor, on a chemically robust skeleton, chemically active, particularly to hydrogenated molecules. The interaction of the sensor with such compounds is read out by measuring the sensor resistance in a four-wire configuration. The sensor performance has been assessed on three hazelnut samples: sound, spoiled, and stink bug hazelnuts. A resistance variation of about ∆R = 0.13 ± 0.02 Ω between sound and damaged hazelnuts has been detected. Conclusions: Our measurements confirm the ability of the sensor to discriminate between sound and damaged hazelnuts. The sensor signal is stable for days, providing the possibility to use this sensor for the monitoring of the storage state of fats and foods in general. © 2023 Society of Chemical Industry

Une entreprise-providence ? Les acteurs de la politique sociale de la Fiat entre collaboration et conflit (années 1920-1960)

Cette contribution analyse l’évolution de la politique sociale de la Fiat, longtemps la plus grande entreprise privée italienne, en relation avec l’histoire des relations industrielles et de l’État-providence. Elle retrace l’essor des initiatives paternalistes dans les années 1920, visant à limiter les conflits industriels et à stabiliser les travailleurs qualifiés, ainsi que leur rôle dans le compromis entre la grande entreprise et l’État fasciste. La guerre a élargi les politiques d’assistance de la Fiat, confiées après la Libération au syndicat et au Parti communiste. Avec la restauration de l’autorité patronale, la politique sociale est redevenue un levier de la gouvernance d’entreprise, mais elle est entrée en crise dans les années 1960 en raison des contradictions liées à la croissance industrielle

Long-lived particle reconstruction downstream of the LHCb magnet

Charged-particle trajectories are usually reconstructed with the LHCb detector using combined information from the tracking devices placed upstream and downstream of the 4 T m dipole magnet. Trajectories reconstructed using only information from the tracker downstream of the dipole magnet, which are referred to as T tracks, have not been used for physics analysis to date. The challenges of the reconstruction of long-lived particles with T tracks for physics use are discussed and solutions are proposed. The feasibility and the tracking performance are studied using samples of long-lived Lambda and KS0 hadrons decaying between 6.0 and 7.6 m downstream of the proton–proton collision point, thereby traversing most of the magnetic field region and providing maximal sensitivity to magnetic and electric dipole moments. The reconstruction can be expanded upstream to about 2.5 m for use in direct searches of exotic long-lived particles. The data used in this analysis have been recorded between 2015 and 2018 and correspond to an integrated luminosity of 6 fb-1. The results obtained demonstrate the possibility to further extend the decay volume and the physics reach of the LHCb experiment

InAs Nanowire-Based Twin Electrical Sensors Enabling Simultaneous Gas Detection

Epitaxially grown InAs NWs are relevant for electrical sensing applications due to the Fermi level pinning at the NW surface and are highly sensitive to the surrounding environment. While a single NW growth batch consists of millions of virtually identical replicas of the same NW, real samples display subtle differences in NW size, shape, and structure, which may affect detection performance. Here, electrical gas detection is investigated in two nominally identical or twin devices fabricated starting from the same NW growth batch. Two individual wurtzite InAs NWs are placed onto a fabrication substrate at a 2 mu m distance with a 90 degrees relative orientation, each NW is electrically contacted, and the nanodevices are exposed to humidity and NO2 flux diluted in synthetic air. Electrical signal versus time is measured simultaneously in each nanodevice upon exposure to different gases and concentrations. The observed detection limit is 2 ppm for NO2 and 20% for relative humidity. Correlation analysis methods are exploited by calculating autocorrelation and cross-correlation functions for the experimental signal pairs, indicating lack of cross-correlation in the signal noise of the two nanodevices, suggesting that signal differences between the twins could be ascribed mainly to nonidealities in the fabrication protocol and nanoscopic differences in the two nanostructures, rather than to different environmental conditions. While InAs nanowires are used here as demonstrators of simultaneous gas sensing, the approach is general and virtually applies to any nanoscale material suitable for the realization of two-terminal electronic devices

Observation of Exotic J/PsiPhi Resonant Structure in Diffractive Processes in Proton-Proton Collisions

The first study of J/Psi Phi production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 fb-1. The data disfavor a nonresonant J/PsiPhi production but are consistent with a resonant model including several resonant states observed previously only in B+->J/Psi Phi K+ decays. The Chi_c0(4500) state is observed with a significance over 6sigma and the Chic1(4274) is confirmed with a significance of more than 4 sigma