Interferometric length metrology for the dimensional control of ultra-stable Ring Laser Gyroscopes

We present the experimental test of a method for controlling the absolute length of the diagonals of square ring laser gyroscopes. The purpose is to actively stabilize the ring cavity geometry and to enhance the rotation sensor stability in order to reach the requirements for the detection of the relativistic Lense-Thirring effect with a ground-based array of optical gyroscopes. The test apparatus consists of two optical cavities 1.32 m in length, reproducing the features of the ring cavity diagonal resonators of large frame He-Ne ring laser gyroscopes. The proposed measurement technique is based on the use of a single diode laser, injection locked to a frequency stabilized He-Ne/Iodine frequency standard, and a single electro-optic modulator. The laser is modulated with a combination of three frequencies allowing to lock the two cavities to the same resonance frequency and, at the same time, to determine the cavity Free Spectral Range (FSR). We obtain a stable lock of the two cavities to the same optical frequency reference, providing a length stabilization at the level of 1 part in $10^{11}$, and the determination of the two FSRs with a relative precision of 0.2 ppm. This is equivalent to an error of 500 nm on the absolute length difference between the two cavities

On the Use of Quantum Chemistry for the Determination of Propagation, Copolymerization, and Secondary Reaction Kinetics in Free Radical Polymerization

Throughout the last 25 years, computational chemistry based on quantum mechanics has been applied to the investigation of reaction kinetics in free radical polymerization (FRP) with growing interest. Nowadays, quantum chemistry (QC) can be considered a powerful and cost-effective tool for the kinetic characterization of many individual reactions in FRP, especially those that cannot yet be fully analyzed through experiments. The recent focus on copolymers and systems where secondary reactions play a major role has emphasized this feature due to the increased complexity of these kinetic schemes. QC calculations are well-suited to support and guide the experimental investigation of FRP kinetics as well as to deepen the understanding of polymerization mechanisms. This paper is intended to provide an overview of the most relevant QC results obtained so far from the investigation of FRP. A comparison between computational results and experimental data is given, whenever possible, to emphasize the performances of the two approaches in the prediction of kinetic data. This work provides a comprehensive database of reaction rate parameters of FRP to assist in the development of advanced models of polymerization and experimental studies on the topic

Aqueous Free-Radical Polymerization of Non-Ionized and Fully Ionized Methacrylic Acid

Water-soluble, carboxylic acid monomers are known to exhibit peculiar kinetics when polymerized in aqueous solution. Namely, their free-radical polymerization rate is affected by several parameters such as monomer concentration, ionic strength, and pH. Focusing on methacrylic acid (MAA), even though this monomer has been largely addressed, a systematic investigation of the effects of the above-mentioned parameters on its polymerization rate is missing, in particular in the fully ionized case. In this work, the kinetics of non-ionized and fully ionized MAA are characterized by in-situ nuclear magnetic resonance (NMR). Such accurate monitoring of the reaction rate enables the identification of relevant but substantially different effects of the monomer and electrolyte concentration on polymerization rate in the two ionization cases. For non-ionized MAA, the development of a kinetic model based on literature rate coefficients allows us to nicely simulate the experimental data of conversion versus time at a high monomer concentration. For fully ionized MAA, a novel propagation rate law accounting for the electrostatic interactions is proposed: the corresponding model is capable of predicting reasonably well the electrolyte concentration effect on polymerization rate. Nevertheless, further kinetic information in a wider range of monomer concentrations would be welcome to increase the reliability of the model predictions

Quantum chemistry investigation of free radical polymerization kinetics : power and limits of the tool

Nella grande varietà di reazioni elementari coinvolte nella polimerizzazione radicalica, si definiscono reazioni secondarie quelle che si verificano accanto allo schema cinetico convenzionale, e che sono tanto influenti sulle caratteristiche di processo quanto sono difficili da caratterizzare sperimentalmente. Dall'altro lato, la chimica computazionale basata sulla meccanica quantistica sta emergendo come una risorsa utile per lo studio delle cinetiche di reazione di polimerizzazione. In questo lavoro, un approccio teorico viene adottato per determinare i parametri cinetici di reazioni secondarie attive nelle polimerizzazione radicale. In particolare, un metodo basato sulla teoria del funzionale di densità viene applicato allo studio di sistemi polimerici con complessità crescente, con l'obiettivo finale ai polimeri e copolimeri acrilici. La rilevanza di reazioni di trasferimento intermolecolare in sistemi polimerici d'interesse è evidenziato, e viene determinato l'effetto di tunneling quantistico sulle reazioni di trasferimento di idrogeno. Il ruolo dei radicali intracatena nella formazione di ramificazioni corte è stabilita dalla caratterizzazione della loro reattività nel contesto di reazioni di trasferimento intramolecolare, propagazione, beta-scissione, e trasferimento ad agente. La chimica quantistica risulta essere un potente strumento per la stima dei parametri cinetici di reazioni poco accessibili nonché nella comprensione dei meccanismi più complessi della polimerizzazione radicalica. Da ultimo, il rapporto costo-efficacia dei metodi basati sulla teoria del funzionale di sensità nel fornire coefficienti cinetici precisi è valutato criticamente rispetto allo studio di condizioni al limite dell'applicazione, come gli effetti di conformazione molecolare e del solvente sulla cinetica di reazione.Among the large number of elementary steps involved in free radical polymerization, secondary reactions running beside the conventional kinetic scheme are as effective on the process features as they are hard to be experimentally characterized. Otherwise, computational chemistry based on quantum mechanics is emerging as a useful resource in the investigation of polymerization reaction kinetics. In this study, a theoretical approach is adopted to determine kinetic parameters of secondary reactions active in radical polymerization. Particularly, an improved density functional theory method is applied to the investigation of polymer systems with increasing complexity, with the final aim being acrylate polymers and copolymers. The relevance of backbiting in well-known free radical polymerization systems is highlighted, determining the effect of quantum tunneling on hydrogen transfer reactions. The role of mid-chain radicals in the origination of short branches is established by the characterization of their reactivity in the context of internal backbiting, propagation, β-scission, and chain transfer to agent reactions. Quantum chemistry is found to be a powerful tool in the estimation of kinetic parameters of less accessible reactions as well as in the understanding of intriguing radical polymerization mechanisms. Eventually, the cost-effectiveness of density functional theory methods in providing accurate rate coefficients is critically evaluated with respect to the study of borderline conditions, such as solvent and molecular conformation effects on reaction kineticsDIPARTIMENTO DI CHIMICA, MATERIALI E INGEGNERIA CHIMICA GIULIO NATTA25CAVALLOTTI, CARLO ALESSANDROFARAVELLI, TIZIAN

The GINGER Project and status of the ring-laser of LNGS

A ring-laser attached to the Earth measures the absolute angular velocity of the Earth summed to the relativistic precessions, de Sitter and Lense-Thirring. GINGER (Gyroscopes IN GEneral Relativity) is a project aiming at measuring the LenseThirring effect with a ground based detector; it is based on an array of ring-lasers. Comparing the Earth angular velocity measured by IERS and the measurement done with the GINGER array, the Lense-Thirring effect can be evaluated. Compared to the existing space experiments, GINGER provides a local measurement, not the averaged value and it is unnecessary to model the gravitational field. It is a proposal, but it is not far from being a reality. In fact the GrossRing G of the Geodesy Observatory of Wettzell has a sensitivity very close to the necessary one. G ofWettzell is part of the IERS system which provides the measure of the Length Of the DAY (LOD); G provides information on the fast component of LOD. In the last few years, a roadmap toward GINGER has been outlined. The experiment G-GranSasso, financed by the INFN Commission II, is developing instrumentations and tests along the roadmap of GINGER. In this short paper the main activities of G-GranSasso and some results will be presented. The first results of GINGERino will be reported, GINGERino is the large ring-laser installed inside LNGS and now in the commissioning phase. Ring-lasers provide as well important informations for geophysics, in particular the rotational seismology, which is an emerging field of science. GINGERino is one of the three experiments of common interest between INFN and INGV

Animal welfare in cattle: opportunities for livestock farms in Veneto and challenges for research

openNegli ultimi anni il benessere animale è diventato un tema di grande attenzione sociale poiché è aumentato il valore dato dai cittadini alla salvaguardia di questo aspetto. Contestualmente sono cambiati gli obiettivi e gli interventi attuati dalla Politica Agricola Comune a sostegno delle aziende agricole, che hanno visto crescere l’importanza della tutela dello stato di benessere degli animali allevati. Notevoli sono stati poi gli sforzi economici messi in atto dall’Unione Europea per finanziare investimenti finalizzati al miglioramento del benessere animale, affiancati dall’impegno preso per un aggiornamento della normativa comunitaria e l’incentivazione del progresso tecnologico su tali aspetti. In questa trattazione verranno analizzati i principali metodi di valutazione del benessere animale e le misure a cui le aziende zootecniche venete possono accedere attraverso la PAC e il CSR Veneto 2023-2027. Un focus specifico è dedicato poi agli interventi finanziati e alla loro influenza sul benessere animale negli allevamenti. Verranno infine presentate le sfide future che la ricerca europea intende affrontare sul tema del benessere animale.In the last years, animal welfare has become a topic of great social attention, as the value given by citizens to the protection of this aspect has increased. At the same time, the objectives and interventions implemented by the Common Agricultural Policy to support farms have changed, which have seen the importance of protecting the welfare status of farmed animals grow. The European Union has also made significant economic efforts to finance investments aimed at improving animal welfare, alongside the commitment made to update community legislation and encourage technological progress on these aspects. This paper will analyse the main methods of assessing animal welfare and the measures that Veneto livestock companies can access through the CAP and the CSR Veneto 2023-2027. A specific focus is then dedicated to the funded interventions and their influence on animal welfare in farms. Finally, the future challenges that European research intends to address on the topic of animal welfare will be presented