From amines to (form)amides: a simple and successful mechanochemical approach

Two easily accessible routes for preparing an array of formylated and acetylated amines under mechanochemical conditions are presented. The two methodologies exhibit complementary features as they enable the derivatization of aliphatic and aromatic amines

Les dynamiques de la végétation et des anthroposystèmes d’altitude cernées par l’anthracologie pastorale et minière à l’échelle d’un haut vallon alpestre (Freissinières, France)

This review paper outlines the reconstruction of vegetation and altitude anthroposystem dynamics, at the scale of the Freissinières high valley, based on the anthracological analysis of mining and (agro-) pastoral carbonised deposits, dating from the Bronze Age to the Renaissance. Archaeological and chronological features of the various deposit contexts, sampling protocol and laboratory methods used, have been outlined. All the obtained data has been summarized in diagrams, and attempts have been made to model vegetation dynamics and areas of firewood supply for mining and pastoral activities. Thus, this study identifies the major subalpine floristic changes that have occurred since the Bronze Age, the development of wood pasture and the lowering of the upper limit of dense forest associated with heathlands and thicket expansion. In addition, this study characterises the evolution of supply practices of fuel wood and the management of uncultivated area -particularly during the Middle Ages- and grasps the leaf-fodder cycle, documented by charcoals at the turn of the Modern era

Electrochemically driven efficient enzymatic conversion of CO2 to formic acid with artificial cofactors

Enzymatic reduction of CO2 to formic acid with the enzyme formate dehydrogenase (FDH) and a cofactor is a promising method for CO2 conversion and utilization. However, the natural cofactor nicotinamide adenine dinucleotide (NADH) shows some drawbacks such as a low reduction efficiency and forms isomers or dimers (1,6 - NADH or NAD dimer) in the regeneration reaction. To overcome them and to improve the production of formic acid, in this work, the artificial cofactors, i.e., the bipyridinium-based salts of methyl viologen (MV2+), 1,1’-dicarboxymethyl-4,4’-bipyridinium bromine (DC2+), and 1,1’-diaminoethyl-4,4’-bipyridinium bromine (DA2+), were used to replace NADH, and the effect of different functional groups on the electrochemical regeneration and catalytic performance in the enzymatic reaction was studied systematically. Also, studies using the natural cofactor NADH were carried out for comparison. It was found that the cofactor with amino groups showed the highest catalytic efficiency (kcat/Km) of 0.161 mM-1min-1, which is 536 times higher than that of the natural cofactor NADH. Molecular Dynamics simulations were conducted to give further molecular insight into the behavior of the cofactors. Analyzing the free energy profiles of the complexes between CO2 in the FDH active site with different artificial cofactors indicated that the artificial cofactor with the amino groups had the highest affinity for CO2, being consistent with the experimental observations

Mechanochemistry: New Tools to Navigate the Uncharted Territory of “Impossible” Reactions

Mechanochemical transformations have made chemists enter unknown territories, forcing a different chemistry perspective. While questioning or revisiting familiar concepts belonging to solution chemistry, mechanochemistry has broken new ground, especially in the panorama of organic synthesis. Not only does it foster new “thinking outside the box”, but it also has opened new reaction paths, allowing to overcome the weaknesses of traditional chemistry exactly where the use of well-established solution-based methodologies rules out progress. In this Review, the reader is introduced to an intriguing research subject not yet fully explored and waiting for improved understanding. Indeed, the study is mainly focused on organic transformations that, although impossible in solution, become possible under mechanochemical processing conditions, simultaneously entailing innovation and expanding the chemical space

Prediction of steel coils mechanical properties and microstructure by using deep learning and advanced data preprocessing techniques

In the production of steel strips, the fulfillment of required product properties is a key factor to improve the company’s productivity and competitiveness. Product characteristics can be evaluated online throughout the length of the strip by means of non–destructive tests such as the IMPOC whose output signal is related to mechanical properties and their uniformity. In this work, a novel approach based on the use of deep–neural–networks and advanced analytics is used to develop a model for the prediction of IMPOC signal from process parameters. The model provides plant managers with an insight into the relationships among process conditions, product characteristics and mechanical properties in order to suitably set up process parameters to meet product requirements. In this work, different model architectures and data processing techniques are evaluated leading an overall prediction error lower than 5% that puts the basis for their integration into the plant

Spectroscopic and in silico studies on the interaction of substituted pyrazolo[1,2-a]benzo[1,2,3,4]tetrazine-3-one derivatives with c-myc g4-dna

Herein we describe a combined experimental and in silico study of the interaction of a series of pyrazolo[1,2-a]benzo[1,2,3,4]tetrazin-3-one derivatives (PBTs) with parallel G-quadruplex (GQ) DNA aimed at correlating their previously reported anticancer activities and the stabilizing effects observed by us on c-myc oncogene promoter GQ structure. Circular dichroism (CD) melting experiments were performed to characterize the effect of the studied PBTs on the GQ thermal stability. CD measurements indicate that two out of the eight compounds under investigation induced a slight stabilizing effect (2–4 °C) on GQ depending on the nature and position of the substituents. Molecular docking results allowed us to verify the modes of interaction of the ligands with the GQ and estimate the binding affinities. The highest binding affinity was observed for ligands with the experimental melting temperatures (Tms). However, both stabilizing and destabilizing ligands showed similar scores, whilst Molecular Dynamics (MD) simulations, performed across a wide range of temperatures on the GQ in water solution, either unliganded or complexed with two model PBT ligands with the opposite effect on the Tms, consistently confirmed their stabilizing or destabilizing ability ascertained by CD. Clues about a relation between the reported anticancer activity of some PBTs and their ability to stabilize the GQ structure of c-myc emerged from our study. Furthermore, Molecular Dynamics simulations at high temperatures are herein proposed for the first time as a means to verify the stabilizing or destabilizing effect of ligands on the GQ, also disclosing predictive potential in GQ-targeting drug discovery

Insight into the Molecular Model in Carbon Dots through Experimental and Theoretical Analysis of Citrazinic Acid in Aqueous Solution

The molecular emission model is the most accredited one to explain the emission properties of carbon dots (CDs) in a low-temperature bottom-up synthesis approach. In the case of citric acid and urea, the formation of a citrazinic acid (CZA) single monomer and oligomers is expected to affect the optical properties of the CDs. It is therefore mandatory to elucidate the possible role of weak bonding interactions in determining the UV absorption spectrum of some molecular aggregates of CZA. Although this carboxylic acid is largely exploited in the synthesis of luminescent CDs, a full understanding of its role in determining the final emission spectra of the produced CDs is still very far to be achieved. To this aim, by relying on purely first-principles density functional theory calculations combined with experimental optical characterization, we built and checked the stability of some molecular aggregates, which could possibly arise from the formation of oligomers of CZA, mainly dimers, trimers, and some selected tetramers. The computed vibrational fingerprint of the formation of aggregates is confirmed by surface-enhanced Raman spectroscopy. The comparison of experimental data with calculated UV absorption spectra showed a clear impact of the final morphology of the aggregates on the position of the main peaks in the UV spectra, with particular regard to the 340 nm peak associated with n-π∗ transition

Etnoarcheologia dei paesaggi alpini di alta quota nelle Alpi occidentali: un bilancio preliminare

The study of the interaction between human groups and mountain environment is crucial for archaeological research. Ethnoarchaeology contributes the analysis of this interaction in modern and contemporary contexts, aimed at creating analogical models for interpreting the past and understanding human strategies in historical and modern periods. The EthWAL project (Ethnoarchaeology of Western Alpine upland Landscapes), started in 2013, and aims to be a reference for the study of human activities in the alpine uplands during the modern and contemporary age. This is a multidisciplinary (associating archaeological methods to ethnography, historiography, spatial analysis and soil analysis) and multiscalar project (small to large scale). Specific attention is given to traditional pastoral huts. The results of this project will be useful for archaeology and contribute to the management of cultural heritage in high altitude landscapes

Formation of citrazinic acid ions and their contribution to optical and magnetic features of carbon nanodots: A combined experimental and computational approach

The molecular model is one of the most appealing to explain the peculiar optical properties of Carbon nanodots (CNDs) and was proven to be successful for the bottom up synthesis, where a few molecules were recognized. Among the others, citrazinic acid is relevant for the synthesis of citric acid-based CNDs. Here we report a combined experimental and computational approach to discuss the formation of different protonated and deprotonated species of citrazinic acid and their contribution to vibrational and magnetic spectra. By computing the free energy formation in water solution, we selected the most favoured species and we retrieved their presence in the experimental surface enhanced Raman spectra. As well, the chemical shifts are discussed in terms of tautomers and rotamers of most favoured species. The expected formation of protonated and de-protonated citrazinic acid ions under extreme pH conditions was proven by evaluating specific interactions with H2 SO4 and NaOH molecules. The reported results confirm that the presence of citrazinic acid and its ionic forms should be considered in the interpretation of the spectroscopic features of CNDs