Publications scientifiques de l'Université de Reims Champagne-Ardenne
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Refractive indices of photochemical haze analogs for Solar System and exoplanet applications: A cross-laboratory comparative study between the PAMPRE and COSmIC experimental setups
No full textInternational audiencePrevious observations of Titan, Pluto, and Solar System gas giants, along with recent observations of exoplanet atmospheres with the James Webb Space Telescope, have taught us that photochemical hazes are ubiquitous and form in a variety of temperature, gas composition, and irradiation environments. Despite their crucial role in understanding their impact on observations and on the planetary radiative budget, the refractive indices of these haze particles remain unknown and are strongly influenced by changes in gas-phase chemistry. In this study, we performed a cross-laboratory investigation to assess the effect of the experimental setup and gas composition on the refractive indices of Titan, Pluto, and exoplanet haze analogs. We report new data in a broad spectral range from UV to far-IR (up to 200 µm) for future use in climate models and retrieval frameworks. We compare the refractive indices of laboratory haze analogs produced from six different gas compositions, in which we varied the relative abundances N 2 /CH 4 and CH 4 /CO in the initial gas mixture, using the PAMPRE (LATMOS, France) and COSmIC (NASA Ames Research Center, USA) experimental setups. We observed strong variations in the k values in the spectral range from UV to near-IR between the different analogs, which are caused by both the experimental setup and changes in the gas N 2 /CH 4 ratio. We find that the gas N 2 /CH 4 ratio has a stronger influence on the haze refractive indices in the entire spectral range compared to the gas CH 4 /CO ratio. The experimental setup is the primary factor affecting the refractive indices, confirming that the gas residence time, irradiation, pressure, and gas temperature are important parameters influencing the composition of the solid analog. The higher n and k values in the UV-visible range, along with the stronger amine, alkene, aromatic, and/or hetero-aromatic signatures in the mid-IR for the COSmIC analogs, are consistent with a greater incorporation of nitrogen into the COSmIC solid analogs compared to the PAMPRE analogs, even at similar nitrogen abundances in the gas phase. Haze analogs produced in gas mixtures without nitrogen, similar to the stratospheres of Solar System gas giants and the H 2 -dominated atmospheres of sub-Neptunes, are generally more transparent with lower n values across the entire spectral range from UV to mid-IR and should therefore be carefully considered in climate and observational applications. The variations in IR absorption features between hazes produced with and without nitrogen could help constrain the presence of N 2 in exoplanet atmospheres
Thermal Dearomative Rearrangement of α-(Prop-2-enyl)-α′-(pyridin-2-yl) Malonate Derivatives toward 4 H -Dihydroquinolizines
No full textInternational audienceReported herein is a thermally induced dearomative rearrangement of α-(aza-heteroaryl)-α'-prop-2-enyl malonate derivatives, affording 4H-dihydroquinolizine derivatives (21 examples, 26-89%). The rearrangement, assisted by microwave heating, afforded diastereoselectively quinolizidine scaffolds, known for their broad biological activities. Experimental results and DFT calculations converge to support a stepwise mechanism initiated by intramolecular [1,4]-addition of the pyridine nitrogen to the activated acrylate moiety, followed by a selective ester transfer
Du bon usage de la qualification d'infraction unique en présence d'une pluralité de pratiques commerciales déloyales similaires
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« De la polyvalence motrice à la conscience écologique : Histoire et actualité des Sections Sportives Scolaires « pratiques de pleine nature » et «montagne »
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Identification and validation of cilia-associated molecular candidates deregulated in severe asthma
No full textInternational audienceBackground: Asthma is characterised by a chronic inflammation and airway remodelling. The functionality of the asthma airway epithelium is altered, suggesting a central role in the pathophysiology. Cilia-associated abnormalities have been reported in the airway epithelium of asthmatic patients, but the mechanisms remain elusive. This study investigated cilia-associated dysregulations in cohorts of patients with severe asthma to identify and characterize key molecular drivers of epithelial airway remodelling.Methods: Transcriptomic data from epithelial bronchial brushing samples of three large cohorts of severe asthma patients and non-asthmatic were analysed: U-BIOPRED (GSE76226, n = 105), SARP (GSE63142, n = 81) and IMSA (GSE158752, n = 42). We focused on cilia-associated genes to highlight common differentially expressed genes in all three cohorts, comparing the non-asthmatic and severe asthma groups. Localisation and expression of the three most dysregulated genes were then validated on ex vivo and in vitro samples and correlated to epithelial airway remodelling features and clinical data.Results: Seventeen genes were significantly dysregulated between the non-asthma and severe asthma groups in all three datasets. We identified the three most dysregulated: PHLDB2 (12.7% [4.6–22.4], p < 0.05), NEK6 (8.4% [5.5–12.8], p < 0.05) and SCNN1G (6.8% [4.3–9.9], p < 0.05) as molecular candidates. In ex vivo severe asthma bronchial biopsies, the protein levels were upregulated 1.2-fold for PHLDB2 (p = 0.2844), 2.4-fold (p < 0.01) for NEK6, and 2.0-fold for SCNN1G (p < 0.05). The expressions of these candidates were correlated with epithelial remodelling features in both groups. In vitro, the expression of SCNN1G was upregulated in airway epithelial cells upon IL-13 stimulation, suggesting that SCNN1G may be dynamically regulated during epithelial differentiation under pro-inflammatory conditions. Finally, protein expression of PHLDB2, NEK6 and SCNN1G in fully differentiated air-liquid interface culture was associated with epithelial remodelling features with or without inflammatory stimulation.Conclusion: This study highlights the dysregulation of three cilia-associated genes, PHLDB2, NEK6, and SCNN1G, in the bronchial epithelium of patients with SA. Their association with epithelial remodelling features and altered differentiation under inflammatory conditions highlights their potential involvement in asthma pathogenesis and their potential as predictive biomarkers or therapeutic targets in severe asthma
Court-circuiter le secteur de l’électricité ? Une analyse des conditions institutionnelles d’émergence des AMEP en France
No full textInternational audienceUsing meso-economic analysis from an industrial economics perspective, the article examines the conditions under which Associations pour la Mutualisation d'une Energie de Proximité (AMEP) emerged in France as a particular form of collective self-consumption within energy communities. A historical review of sectoral developments since the 20th century reveals the market and institutional regulations that have enabled the emergence of citizen actors in the electricity sector, as well as the intertwining of political, productive and technical dynamics in the emergence of new modes of electricity production, supply and consumption. The article thus highlights the logic of productive and political differentiation of AMEP with regard to industrial actors and with regard to other energy communities involved in structuring and disseminating this new model.Dans une perspective méso-économique issue de l’économie industrielle, l’article revient sur les conditions d’émergence des Associations pour la Mutualisation d’une Énergie de Proximité (AMEP) en France, comme forme particulière d’autoconsommation collective au sein du paysage des communautés d’énergie. La lecture historique des évolutions sectorielles à l’œuvre depuis le XXe siècle rend compte des régulations marchandes et institutionnelles ayant permis l’irruption d’acteurs citoyens dans le secteur de l’électricité mais aussi de l’enchevêtrement de dynamiques politiques, productives et techniques dans l’émergence de nouveaux modes de production, fourniture et consommation d’électricité. L’article met ainsi en lumière les logiques de différenciation productives et politiques des AMEP vis-à-vis des acteurs industriels et des autres communautés d’énergie qui accompagnent la structuration et la diffusion de ce nouveau modèle
A visualizable and widely applicable steric repulsion descriptor for guiding experimental chemistry
No full textInternational audienceWhile steric effects fundamentally shape molecular behavior and are experiencing renewed interest across chemistry, visualizing where they occur remains challenging. Indeed, steric interactions have traditionally been depicted in a qualitative, often sketchy manner. We present SELF (Steric Exclusion Localization Function), which enables the quantification, atomic resolution, and visualization of steric repulsion in three dimensions (whether between molecules or between fragments of a single molecule) directly from quantum-mechanical calculations. Accessible through the user-friendly IGMPlot software, SELF transforms abstract quantum-mechanical concepts into visual insights that chemists can immediately interpret and apply. We illustrate SELF's versatility across diverse chemical systems: from understanding atropisomerism in pharmaceutical scaffolds to rationalizing selectivity in catalysis through steric effects of phosphorus ligands in organometallic chemistry. Unlike traditional quantum-mechanical methods which condense the characteristics of steric effects into a single number, SELF provides unprecedented spatial resolution of steric clashes while maintaining rigorous quantitative analysis. This approach bridges the gap between theoretical concepts and practical chemical understanding, making sophisticated quantum-mechanical analysis accessible to the broader chemical community. We hope this tool will prove valuable for chemical design, research applications, and teaching steric effects
Jesuit Rhetoric across Space and Time: Local and Global Perspectives
No full textInternational audienceA product of Renaissance educational thought, Jesuit rhetoric has trained generations of churchmen and lay citizens right up to the present day. This book aims to show the wealth of current international research on Jesuit rhetoric, in its pedagogical dimension (from sixteenth-century manuals to today's university writing courses), its practical implementation (in speeches, music or theology). Its chapters span both religious contexts—engagements with Protestants, Jews, Orthodox Christians, and Dominicans—and geographical ones, including encounters between Europe and regions such as Sri Lanka, China, and Japan
