Crossed-beam universal-detection reactive scattering of radical beams characterized by laser-induced-fluorescence: the case of C2 and CN

International audienceWe have generated continuous supersonic beams of dicarbon (C2) and cyano (CN) radicals by a high-pressure radio-frequency discharge beam source starting from dilute mixtures in rare gases of suitable precursor molecules. We have subsequently characterized their internal quantum state distributions by laser-induced-fluorescence (LIF) in a new crossed molecular beam-laser apparatus. We have used these supersonic beams to study the reactive scattering of C2 and CN radicals with unsaturated hydrocarbons. We report here on the C2 and CN radical beam characterization by LIF and on dynamics studies of the reactions CN + C2H2 (acetylene) and CN + CH3CCH (methylacetylene) by the crossed molecular beam scattering technique with universal mass spectrometric detection and time-of-flight analysis. The role of CN rovibrational excitation on the dynamics of the CN + C2H2 reaction is discussed with reference to previous dynamics and kinetics studies. These reactions are of interest in the chemistry of planetary atmospheres (Titan) and the interstellar medium as well as in combustion

Is PPP a tool for achieving Sustainable Development Goals? An empirical analysis in the Italian cultural heritage sector

This paper discusses the significance of Public-Private Partnerships (PPPs) in achieving sustainable development goals (SDGs) and analyses such partnerships in the context of fundraising strategies. The focus is on assessing the sensitivity of PPPs to sustainability concerns, especially when the State relies on external financing. The paper explores how collaboration between the private and public sectors aligns with the restoration and conservation of assets, financial returns for donors, and the pursuit of sustainable objectives. Given the absence of a standardized ranking for sites based on SDG impact, the study investigates the willingness to finance sustainability among both financing actors and the public recipients. The study specifically examines the long-term effectiveness of the Italian ArtBonus tool in contributing to SDGs. Descriptive statistical analysis is carried out in order to provide a first analytical picture of the diffusion of the Italian tool of ArtBonus and deductive content analysis of three case studies is employed to evaluate the level of transparency of communication regarding the SDG's targets. The research emphasizes the need for a consistent method for using SDG targets related to cultural heritage. A concrete reporting method is proposed, aiming to establish a dual commitment for receiving institutions, ensuring accountability at both the project's inception and conclusion. This approach encourages the integration of activities contributing to SDGs, providing guidelines for users and promoting transparency by requiring beneficiaries to inform the community about funded projects and their sustainability impact. Further research is recommended to expand the study and refine the reporting system

Étude des algorithmes de sélection d’unités pour la synthèse de la parole à partir du texte

This PhD thesis focuses on the automatic speech synthesis field, and more specifically on unit selection. A deep analysis and a diagnosis of the unit selection algorithm (lattice search algorithm) is provided. The importance of the solution optimality is discussed and a new unit selection implementation based on a A* algorithm is presented. Three cost function enhancements are also presented. The first one is a new way – in the target cost – to minimize important spectral differences by selecting sequences of candidate units that minimize a mean cost instead of an absolute one. This cost is tested on a phonemic duration distance but can be applied to others. Our second proposition is a target sub-cost addressing intonation that is based on coefficients extracted through a generalized version of Fujisaki's command-response model. This model features gamma functions modeling F0 called atoms. Finally, our third contribution concerns a penalty system that aims at enhancing the concatenation cost. It penalizes units in function of classes defining the risk a concatenation artifact occurs when concatenating on a phone of this class. This system is different to others in the literature in that it is tempered by a fuzzy function that allows to soften penalties for units presenting low concatenation costs.La synthèse de la parole par corpus (sélection d'unités) est le sujet principal de cette thèse. Tout d'abord, une analyse approfondie et un diagnostic de l'algorithme de sélection d'unités (algorithme de recherche dans le treillis d'unités) sont présentés. L'importance de l'optimalité de la solution est discutée et une nouvelle mise en œuvre de la sélection basée sur un algorithme A* est présenté. Trois améliorations de la fonction de coût sont également présentées. La première est une nouvelle façon – dans le coût cible – de minimiser les différences spectrales en sélectionnant des séquences d'unités minimisant un coût moyen au lieu d'unités minimisant chacune un coût cible de manière absolue. Ce coût est testé pour une distance sur la durée phonémique mais peut être appliqué à d'autres distances. Notre deuxième proposition est une fonction de coût cible visant à améliorer l'intonation en se basant sur des coefficients extraits à travers une version généralisée du modèle de Fujisaki. Les paramètres de ces fonctions sont utilisés au sein d'un coût cible. Enfin, notre troisième contribution concerne un système de pénalités visant à améliorer le coût de concaténation. Il pénalise les unités en fonction de classes reposant sur une hiérarchie du degré de risque qu'un artefact de concaténation se produise lors de la concaténation sur un phone de cette classe. Ce système est différent des autres dans la littérature en cela qu'il est tempéré par une fonction floue capable d'adoucir le système de pénalités pour les unités présentant des coûts de concaténation parmi les plus bas de leur distribution

Combined crossed beam and theoretical studies of the C(1D)+CH4 reaction

The reaction involving atomic carbon in its first electronically excited state 1D and methane has been investigated in crossed molecular beam experiments at a collision energy of 25.3 kJ mol-1. Electronic structure calculations of the underlying potential energy surface (PES) and Rice–Ramsperger–Kassel–Marcus (RRKM) estimates of rates and branching ratios have been performed to assist the interpretation of the experimental results. The reaction proceeds via insertion of C(1D) into one of the C-H bonds of methane leading to the formation of the intermediate HCCH3 (methylcarbene or ethylidene), which either decomposes directly into the products C2H3 + H or C2H2 + H2 or isomerizes to the more stable ethylene, which in turn dissociates into C2H3 + H or H2CC + H2. The experimental results indicate that the H-displacement and H2-elimination channels are of equal importance and that for both channels the reaction mechanism is controlled by the presence of a bound intermediate, the lifetime of which is comparable to its rotational period. On the contrary, RRKM estimates predict a very short lifetime for the insertion intermediate and the dominance of the H-displacement channel. It is concluded that the reaction C(1D)+CH4 cannot be described statistically and a dynamical treatment is necessary to understand its mechanism. Possibly, nonadiabatic effects are responsible for the discrepancies, as triplet and singlet PES of methylcarbene cross each other and intersystem crossing is possible. Similarities with the photodissociation of ethylene and with the related reactions N(2D) + CH4, O(1D) + CH4 and S(1D) + CH4 are also commented on

Reaction dynamics and relative yields of the H- and CH3-displacement channels in the O + CH3CCH reaction

The O + CH3CCH reaction has been investigated in crossed molecular beam experiments at a collision energy of 38.7 kJ mol−1. Product angular and translational energy distributions have been measured for the H- and CH3-displacement channels and their relative branching ratio has been determined. The CH3-displacement channel is more important (by a factor of 3) than the H-displacement channel. This is not explained by a preference for the addition on the substituted acetylenic carbon atom, but rather by the different tendencies of the two addition intermediates CH3CCOH and CH3COCH to undergo intersystem crossing to the underlying singlet potential energy surface.Web of Science602625

Reaction dynamics and relative yields of the H- and CH3-displacement channels in the O + CH3CCH reaction

The O + CH3CCH reaction has been investigated in crossed molecular beam experiments at a collision energy of 38.7 kJ mol−1. Product angular and translational energy distributions have been measured for the H- and CH3-displacement channels and their relative branching ratio has been determined. The CH3-displacement channel is more important (by a factor of 3) than the H-displacement channel. This is not explained by a preference for the addition on the substituted acetylenic carbon atom, but rather by the different tendencies of the two addition intermediates CH3CCOH and CH3COCH to undergo intersystem crossing to the underlying singlet potential energy surface.Web of Science602625

Isomer-Specific Chemistry in the Propyne and Allene Reactions with Oxygen Atoms: CH3CH + CO versus CH2CH2 + CO Products

reserved9We report direct experimental and theoretical evidence that, under single-collision conditions, the dominant product channels of the O(3P) + propyne and O(3P) + allene isomeric reactions lead in both cases to CO formation, but the coproducts are singlet ethylidene (1CH3CH) and singlet ethylene (CH2CH2), respectively. These data, which settle a long-standing issue on whether ethylidene is actually formed in the O(3P) + propyne reaction, suggest that formation of CO + alkylidene biradicals may be a common mechanism in O(3P) + alkyne reactions, in contrast to formation of CO + alkene molecular products in the corresponding isomeric O(3P) + diene reactions, either in combustion or other gaseous environments. These findings are of fundamental relevance and may have implications for improved combustion models. Moreover, we predict that the so far neglected 1CH3CH + CO channel is among the main reaction routes also when the C3H4O singlet potential energy surface is accessed from the OH + C3H3 (propargyl) entrance channel, which are radical species playing a key role in many combustion systems.Vanuzzo, Gianmarco; Balucani, Nadia; Leonori, Francesca; Stranges, Domenico; Falcinelli, Stefano; Bergeat, Astrid; Casavecchia, Piergiorgio; Gimondi, Ilaria; Cavallotti, CarloVanuzzo, Gianmarco; Balucani, Nadia; Leonori, Francesca; Stranges, Domenico; Falcinelli, Stefano; Bergeat, Astrid; Casavecchia, Piergiorgio; Gimondi, Ilaria; Cavallotti, CARLO ALESSANDR

Testi, carteggi e metadati: il caso Fracassetti

L’archivio di Giuseppe Fracassetti (1802-1883), conservato presso la Biblioteca Civica “Romolo Spezioli” di Fermo, documenta il grande interesse dello studioso nei confronti della letteratura di ogni tempo. Nell’ingente patrimonio di autografi conservato nel Fondo, spiccano in particolare le carte delle traduzioni dal greco, dal latino e dalle lingue straniere, a cui lo studioso dedicò molti anni di febbrile attività: studi preparatori, fogli di abbozzi, stesure in pulito, che consentono di ripercorrere l’intero iter redazionale di ciascuna delle sue opere. Il tutto affiancato da fitti carteggi, testimoni, una volta di più, della continua (e condivisa) riflessione cui Fracassetti sottopose i propri lavori. Il presente volume raccoglie i risultati di una prima rassegna di studi, vale a dire il convegno “Testi, carteggi e metadati: il caso Fracassetti”, tenutosi a Bologna il 17 marzo 2022 e articolato in tre sezioni: Fra edito e inedito, Strumenti e metodi, Esperienze di lavoro. Si tratta di dieci contributi (e un’appendice), che illuminano gli studi, i volgarizzamenti, i carteggi, editi e inediti, di Fracassetti, e propongono nuovi metodi e strumenti per rendere più fruibile la sua produzione