Portail HAL UHA (Université de Haute-Alsace)
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Catalytic Deprotection of Alkyne Dicobalt Hexacarbonyl Complexes using Near-Infrared Photocatalysis
No full textInternational audienceDicobalt hexacarbonyl complexes are well-known for their applications in Nicholas reaction or simply as protecting group for alkynes. To recover the alkyne, demetallation is necessary, which usually involves a stoichiometric amount of an oxidizing agent or a strong ligand. This article reports a demetallation methodology based on a photocatalytic process. This approach employs a photocatalyst under aerobic conditions and the optimal results were achieved using mild nearinfrared irradiation. Mechanistic investigation is also presented to elucidate how the photocatalytic system promotes this deprotection. This tool is compatible with one-pot reaction and orthogonal deprotection of alkyne offering new perspectives for further applications
Tailoring van der Waals interactions in ultra-thin two dimensional metal–organic frameworks (MOFs) for photoconductive applications
No full textInternational audienceThe diverse structural tunability of 2-dimensional π-stacked layered metal–organic frameworks (2D MOFs) enables the control of charge carrier mobility to achieve specific photoconductive characteristics. This study demonstrates the potential of various theoretical methodologies and frameworks in establishing a correlation between structure and functionality for such purposes. Through a focus on the archetypal Ni3(HITP)2 2D MOF, we examine the impact of quantum confinement and stacking fault defects on the absorption spectra using our recently-developed Frenkel–Holstein Hamiltonian. Specifically, the relationship between optical properties and number of layer units along the π-stacking direction is discussed. We employ Marcus rate theory to evaluate vertical carrier mobility subject to inter-layer proximity and different crystal packing which affect van der Waals interactions between layers. The insights presented in this research can inform the development of guidelines for enhancing photoconductive properties in 2D MOF nanosheets
High Photoinitiating Efficiency of Benzothioxanthene-based Oxime Esters in Photopolymerization via Photocleavage and/or Single Electron Transfer under Visible Light and Sunlight
No full textInternational audienceIn this work, six benzothioxanthene-based oxime esters were employed as photoinitiators for photopolymerization with visible light (LED) and sunlight. Their abilities to behave as Type I photoinitiators by mean of a photocleavage mechanism of oxime esters but also in multicomponent photoinitiating system with an iodonium salt (through an electron transfer mechanism) were both explored with the different structures. Due to their broad absorption spectra tailing up 600 nm, photoinitiating properties of the benzothioxanthene-based oxime esters were systematically tested under excitation with low-intensity LED light at wavelengths of 405 nm and 450 nm. Additionally, to the polymerization tests done under artificial light, different benzothioxanthene-based oxime esters were also investigated as solar photoinitiators and displayed a high reactivity in France (Western Europe) even in winter conditions. For the best candidates i.e. the most reactive structures, direct laser write experiments were carried out, evidencing the interest of these structures
Chauffage domestique au bois : Bûches traditionnelles versus bûches densifiées
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CONTACT FORMS ON THE SIMPLE LIE GROUP SL(2p, K)
No full textWe construct a contact form on the simple Lie group SL(2p) for any p. This form is invariant by the action of the subgroup SO(2p)
Was there an alternative to monarchy ? Radicalism and antiroyalism in the 1640s
No full textInternational audienceWhile republicanism in the 1650s is now well documented, relatively little scholarly attention has been paid to antiroyalism in the 1640s. This contribution aims to fill a gap by focusing on forms of antimonarchism in those seminal years in the history of the British Isles—a decade that culminated in the trial and execution of King Charles I. It teases out the complexity and inconsistency of Civil War radicals’ attitudes to monarchy as a political regime, and hence to the future political settlement of the kingdom, first after the king’s defeat in the first Civil War in 1646, second at the time of the radicalisation of the New Model Army in 1647, and then after the regicide in 1649 and the establishment of the republic. Writings by Leveller figures and New Model Army radicals are examined with reference to their authors’ positioning on the Stuart monarchy, King Charles in particular, and on monarchy at large. I discuss the possible alternatives to monarchy as envisaged by these radicals—or the actual lack of alternatives—and I argue that such attitudes were mostly context-based: they were prompted by historical circumstances, as much as they were shaped by the theoretical underpinnings of their discourse.Si le républicanisme des années 1650 est à présent bien connu, l’anti-royalisme des années 1640 reste relativement peu étudié. Cet article a pour but de combler un vide en s’attachant aux formes que prit l’opposition à la monarchie dans ces années révolutionnaires, dont l’apogée fut le procès et l’exécution du roi Charles Ier. Il s’efforce de mettre en lumière la complexité et, parfois, l’incohérence des positions des radicaux anglais des guerres civiles quant à la monarchie en tant que régime politique et, partant, quant au règlement de la crise politique, d’abord à la suite de la défaite du roi lors de la première guerre civile en 1646, ensuite lors de la radicalisation de l’Armée du Nouveau Modèle en 1647, et enfin après le régicide en 1649 et la mise en place de la république. Divers écrits produits par les Niveleurs et des radicaux de l’Armée du Nouveau Modèle sont étudiés relativement au positionnement de leurs auteurs sur la monarchie Stuart, le roi Charles en particulier, et sur la monarchie au sens large. Nous tentons d’identifier les alternatives possibles à la monarchie, ou l’absence d’alternatives, et faisons l’hypothèse que ce positionnement, fortement lié au contexte des guerres civiles, fut conditionné tout autant par les circonstances historiques que par l’assise idéologique des acteurs
Quantification of activated carbon functional groups and active surface area by TPD-MS and their impact on supercapacitor performance
No full textInternational audienceCarbon oxygenated functional groups and active sites play an important role in the interactions with the electrolytes in aqueous supercapacitors. For the first time, correlations between each type of O-surface groups and electrochemical performance are established by means of thermodesorption coupled with mass spectrometry (TPD-MS). A set of five activated carbons and one soft-salt templated carbon, were studied in three different pH electrolytes, 1M H2SO4, 1M KOH and 1M Na2SO4. Linear correlations between surface groups and capacitance were found: acidic groups such as carboxylic acid and phenol-ether groups improve capacitance, whereas carbonylquinone groups are detrimental. Moreover, active surface area (ASA) is for the first time measured for activated carbons thanks to a new protocol, which minimises material burn-off during oxygen chemisorption. In addition, a new approach consisting in the quantification of the ASA is proposed. It has been highlighted that certain active sites are linearly correlated to an improvement of capacitance. Although the oxygen surface groups and ASA improve the capacitance via pseudo-capacitance phenomena, the capacitive mechanisms, governed by the porosity of the activated carbons, are shown to be predominant. Among all materials, the soft-salt templated carbon gives the best electrochemical performance. Indeed, it combines a large quantity of carboxylic acid and phenol-ether surface groups as well as appropriate ASA. Moreover, it has a high specific surface area (2556 m²•g -1 ) and optimal pore size (0.89 nm). All these characteristics, provide a high capacitance, a high rate capability and a high capacitance retention after 10,000 cycles
CINDERELLA A semi-automatic user-friendly tool for curation of mass spectrometry metabolomic data
No full textInternational audienceIn non-targeted metabolomics, the automatic pre-processing of mass spectrometry data, coupled with liquid or gas chromatography, is of great importance to highlight true biomarkers of interest while limiting false positives or false negatives. Many software offer more or less robust algorithms for the pre-processing stages (peak detection, alignment and integration), which generate hundreds or even thousands of features, but do not necessarily integrate pre-treatment (or cleaning) methods. In fact, a significant proportion of the signals extracted at the end of data pre-processing still need to be corrected or eliminated before the data can be statistically processed. Existing automated tools are often too strict and lack in visualisation steps. Thus, we are developing CINDERELLA (Comprehensive INtegrated Data Editing and Refinement for metabolomics by ELiminating Low-quality signals and Artifacts), an R tool with a user-friendly interface for semi-automatic and supervised artifact elimination. Based on pre-processed data and sample metadata, CINDERELLA can, at the user's request, (i) remove features and/or samples containing too many missing values and replace the remaining missing values so as not to impact statistical tests, (ii) perform sample normalisation with the internal standard values and/or the amount of biological samples, (iii) correct batch effects, (iv) filter out artifacts and biologically irrelevant signals and (v) assess the quality of the remaining features. Each step is accompanied by interactive decision-support tables and graphs, which are compiled in an automatic output report for monitoring the data treatment process
Controlling photopolymerization reaction in layer‐by‐layer photopolymerization in 3D printing
No full textInternational audienceAbstract Today, controlling the photopolymerization process during the 3D printing in vat photopolymerization is a key challenge. In this work, it is shown that using a relatively limited set of parameter, it is possible to estimate key factors involved in such process. On the basis of 16 formulations containing different concentrations of photoinitiator and UV filter, attempt was made to rationalize the photonic parameters used in the 3D printing process, that is, the depth of penetration Dp and the critical energy Ec . It is shown that the experimental Dp values can be correlated with calculated ones from Bouguer–Beer–Lambert law. Real‐time Fourier‐transform infrared spectroscopy (RT‐FTIR) experiments were performed under similar conditions as in 3D printing. The conversion profiles were used to estimate the Ec values. The limits of this approach was discussed as a function of the UV filter concentration. Finally, the RT‐FTIR curves are exploited to predict the in‐depth conversion of the different 3D printed layers and compared to experimental results obtained by confocal Raman microscopy