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Divergent Reactivity of E / Z ‐Azobenzene‐Based Phosphine‐Gold Catalysts: Toward an ON‐ON Catalytic Photoswitch Process
No full textInternational audienceThis work discloses a strategy for the implementation of ON‐ON organometallic catalytic processes using photoresponsive phosphine ligands. The approach leverages on the regiodivergent reactivity of mono‐ and bimetallic gold complexes that results from π‐ vs σ,π‐activations of alkynyl‐substituted urea substrates, for the selective formation of either dihydroquinazolinone or indole‐carboxamide products, via intramolecular hydroamidation
L'énergie photovoltaïque sous concentration: des cellules solaires sous «stéroïdes »?
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Macrophages restrict tumor permissiveness to immune infiltration by controlling local collagen topography through a Tcf4-Collagen3 fibrotic axis
No full textAbstract During tumorigenesis, the extracellular matrix (ECM), which constitutes the structural scaffold of tissues, is profoundly remodeled. While the impact of such remodeling on tumor growth and invasion has been extensively investigated, much less is known on the consequences of ECM remodeling on tumor infiltration by immune cells. By combining tissue imaging and machine-learning, we here show that the localization of T lymphocytes and neutrophils, which orchestrate antitumor immune responses, can be predicted by defined topographical features of fibrillar collagen networks. We further show that these collagen topographies result from the activation of a fibrotic pathway controlled by the transcription factor Tcf4 upon depletion of tumor-associated macrophages at late tumor stages. This pathway promotes the deposition of collagen 3 by both tumor and stromal cells, resulting in intermingled collagen networks that favor intra-tumoral T cell and neutrophil localization. Importantly, analysis of human colorectal cancer public bulk RNAseq databases showed a strong correlation between Tcf4 and collagen 3 , as well as between the expression of these genes and tumor infiltration by T lymphocytes and neutrophils, attesting the clinical relevance of our findings. This study highlights the key structural role of macrophages on the tumor extracellular matrix and identifies collagen network topographies as a major regulator of tumor infiltration by immune cells
Cospatial ice mapping of H2O with CO2 and CO across a molecular cloud with JWST/NIRCam
No full textInternational audienceIn the coldest regions of molecular clouds, carbon and oxygen are incorporated into icy dust grains. Despite its outsized role in star and planet formation, sequential formation of ice is poorly constrained. Infrared spectroscopy probes ice chemistry, but previous telescopes observed insufficient lines of sight to map a single cloud. Here we present cospatial maps of H 2 O, CO 2 and CO ice over the central region of the Chamaeleon I molecular cloud, using 44 lines of sight observed with the James Webb Space Telescope. Correlations at column densities ten times larger than previous work suggest additional CO 2 ice formation in CO ice for the densest lines of sight. This large statistical sampling within a single cloud represents a step change in ice mapping, eliminating averaging over clouds with different intrinsic chemical environments. Mapping opens the door to probing gas–grain exchanges, snow lines and chemical evolution in the densest regions and drawing conclusions on the impact of ice chemistry on wider astrophysics
Prediction of the aqueous redox properties of functionalized quinones using a new QM/MM variational formulation
No full textInternational audienceWe recently proposed to couple quantum mechanics (QM) methods with molecular density functional theory (MDFT) to describe mixed quantum-classical systems [J. Chem. Phys. 161, 014113 (2024)]. This approach is particularly appropriate to account for solvent effect into QM calculations. Motivated by the growing interest in quinones as potential electrolytes for aqueous redox-flow batteries, we apply the QM/MDFT framework to compute the two-electrons redox potentials of a series of Benzoquinone/Hydroquinone couples in aqueous solution. However, since these molecules are made of several dozens of atoms, their geometries are not trivial. This motivates the development of a geometry optimization procedure within the QM/MDFT framework.To this end, we introduce a new variational formulation for the grand potential of a mixed quantum-classical system. Within the Born-Oppenheimer approximation, and neglecting electronic entropy, the quantum solute is described by a product of electronic and nuclear density matrices, both depending parametrically on coordinates of the classical solvent. It can then be shown that a functional of the total density matrix satisfies a variational principle for the grand potential. Using a mean-field approximation, we express the grand potential of the mixed quantum-classical system as a variational problem which depends only on the nuclear density matrix. The nuclei experience an external field generated by the electronic and classical one-particle densities.In practice, the computation of the grand potential is reduced to a sequence of density optimizations. First, the classical solvent density and the solute electronic density are optimized for a fixed solute nuclear geometry, using the previously reported mixed quantum mechanics/classical procedure. Subsequently, the solute geometry is optimized for a fixed solvent configuration. Finally, the redox potentials of a selection of Benzoquinone/Hydroquinone couples are computed after geometry optimizations. The predictions are in good agreement with QM calculation using a continuum solvent model and with experimental data</p
Using foams for the oxidative dissolution of copper particles: the transport of reactants is controlled by the foam structure
No full textInternational audienceWe study the oxidation of micrometric copper particles in rotating aqueous foams by oxygen O 2 present in the gas bubbles and in the presence of protons H + in the continuous phase. Our goal is to understand the link between the reaction kinetics and the transfer of the three reactants present in three different phases in the foam by monitoring foam structure using simple experimental tools. Measuring the bubble size evolution and the foam liquid fraction enable us to obtain an insight into the transfer of O2 by diffusion in the thin liquid films, while measuring the foam liquid fraction and using a pH sensitive dye enable us to observe the distribution of protons within the foams. Finally, the trapping of particles in the dry foams can be observed directly with a camera. We vary the rotating speed which influences the amount of liquid effectively incorporated inside the foams, which in turn controls the quantity of particles and protons within the foams. We prove that the foam structure controls the transfer of reactants and hence the reaction kinetics. Wetter foams ensure a steady transport of particles and protons, resulting in a steady increase of the amount of copper dissolved over time. In the drier foams, the O2 transfer is faster so that the kinetics is faster than in wet foams at short times. Yet the transport of the particles and the continuous phase is hampered leading to a slower kinetics at longer times. These results will guide the design and handling of reactive foams when used as chemical reactors
Enhancing Open-Circuit Voltage in Infrared PbS Quantum Dot Heterojunction Solar Cells Using ZnO Nanowires Passivated by Atomic Layer Deposition of Al 2 O 3
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Purification protocol of hypertrophied hepatic stellate cells for their transcriptomic characterization from CDAHFD mice liver
No full textSummary Hepatic stellate cells (HSC) are known for their major role in hepatic fibrosis. Recently, it has been shown that different subpopulations of HSC co-exist during fibrogenesis and play different roles in the establishment of fibrosis. We previously highlighted, in murine model and human biopsies, a specific subpopulation of hypertrophied HSC (hypHSC) which exhibit exacerbated retinoid droplets and were closely associated to collagen fibers. The present study describes the purification protocol of hypHSC developed from a murine model of metabolic liver fibrosis. Liver dissociation followed by density gradient and fluorescence assisted cell sorting allowed us to obtain higlhly pure hypHSC preparations. Then, a transcriptomic analysis (bulk RNAseq) of hypHSCs versus quiescent HSCs purified from healthy mouse liver, was performed. This showed that hypHSCs molecular signature differs from HSC subtypes already described in the literature, with a “hybrid” profile of both inflammation and matrix remodeling. Our study highlights that a phenotype-to-molecular approach can provide complementary elements to single-cell molecular approaches
CO-to-sugars conversion from one-pot two-step electroorganocatalytic process
No full textInternational audienceThe conversion of C1 molecules (single-carbon species) into C n products (carbon chains) is a key challenge for developing sustainable chemical feedstocks to replace fossil resources. Carbohydrates, a vital class of complex polycarbon molecules, are mainly extracted from biomass, but de novo synthesis provides a complementary route to access rare and non-natural carbohydrates. Here, we report a fully integrated, one-pot two-step system converting carbon monoxide (CO) into carbohydrates. This process couples the electroreduction of CO to formaldehyde with the organocatalytic oligomerization of formaldehyde into C5-6 carbohydrates selectively. This work establishes a novel pathway to utilize CO as a building block for synthesizing complex carbon chains