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Red Emissive 1D Copper(I) Thiolates and Green Emissive 2D Copper(I) Halide Thiolates Displaying Second Harmonic Generation and Two-Photon Absorption Processes
No full textfffInternational audienceCopper(I), as a d10 metal, is a promising affordable noncritical raw material finding great interest for the development of photoluminescent materials. Halide and thiolate-based copper(I) compounds are known for their efficient emission and good stability. In order to rationalize the effect of these two anions in the structure and photoemission of Cu(I) compounds, two new families of coordination polymers have been synthesized: the copper(I)-thiolates: [Cu(p-SPhX)]n (X = F, Cl, Br), and the copper halide thiolates: [Cu3Cl(p-SPhX)2]n (X = F, Cl, Br). The two families display different structural dimensionalities: 1D [Cu(p-SPhX)]n versus 2D [Cu3Cl(p-SPhX)2]n and they exhibit distinct photophysical properties: [Cu(p-SPhX)]n shows usual solid-state red emission, while [Cu3Cl(p-SPhX)2]n hasintense solid-state green anti-Stokes emission, associated, for the noncentrosymmetric compounds, X = F and Br, to non-linear optical (NLO) response, pointing out the effect of the weak halogen interactions of the thiolate ligands on the symmetry and the properties
Ressources éthiques interdisciplinaires pour une autonomie individuelle durable y compris dans la vieillesse. Appropriation subjective du corps, philosophie des âges de la vie et enjeux technologiques dans l’hypermodernité démocratique
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La sociologie française du sport et l’introduction des travaux de Norbert Elias et Eric Dunning. Le rôle d'un lecteur et d'un traducteur. Entretien avec Jacques Defrance
No full textHuman pluripotent stem cell-derived hepatic progenitors exhibit a partially hypoimmunogenic phenotype and actively inhibit immune responses
No full textInternational audienceIntroduction : GStemHep cells are human cryopreserved hepatic progenitors derived from pluripotent of stem cells (GStem cells) using a cGMP-compliant protocol. They were highly effective in rescuing mice from acute liver failure. Methods : The objective of this study was to analyze the immunogenicity and immunoregulatory properties of GStemHep cells. Results : As compared to GStem cells, GStemHep cells showed complete loss of HLA-I (ABC) and they lacked of expression of HLA-II, HLA-G, HLA-E and PD-L1. GStemHep cells also showed increased expression of CD47, maintained high expression of indoleamine 2,3-dioxygenase (IDO) and heme oxygenase-1 (HO-1) and reduced expression of CD200. In comparison with GStem cells, GStemHep cultured in inflammatory conditions increased the expression of PD-L1, CD200, HO-1, HLA-E, CD47 and HLA-I (ABC) as well as maintained expression of IDO and were negative for HLA-II and HLA-G. GStemHep culture in basal or inflammatory conditions has a low or absent immunogenic activity on T cells, associated to a suppressive effect on proliferation partially mediated by IDO. We observed phagocytosis of GStemHep by macrophages that was partially inhibited by CD47 expression. NK cells were activated by resting GStemHep cells. Upon culture in inflammatory conditions that induced expression of HLA-I molecules in GStemHep cells NK cell activation was reduced. Thus, GStemHep cells are partially hypoimmune cells due to the expression of several immune checkpoint inhibitors and the absence of HLA-I molecules. In inflammatory conditions, the expression of several of these molecules was increased but also of HLA-I that could be immunogenic for T cells but it was inhibitory for NK cells. Discussion : GStemHep cells show a favorable immunological profile for their use as allogeneic off-the shelf treatment of liver diseases with loss of hepatocyte function
First observation of ultra-long-range azimuthal correlations in low multiplicity pp and p-Pb collisions at the LHC
No full textInternational audienceThis study presents the first observation of ultra-long-range two-particle azimuthal correlations with pseudorapidity separation of () in proton-proton (pp) and () in proton-lead (p-Pb) collisions at the LHC, down to and below the minimum-bias multiplicity. Two-particle correlation coefficients () are measured after removing non-flow (jets and resonance decays) contributions using the template-fit method across various multiplicity classes, providing novel insights into the origin of long-range correlations in small systems. Comparisons with the 3D-Glauber + MUSIC + UrQMD hydrodynamic model reveal significant discrepancies at low multiplicities, indicating possible dynamics beyond typical hydrodynamic behavior. Initial-state models based on the Color Glass Condensate framework generate only short-range correlations, while PYTHIA simulations implemented with the string-shoving mechanism also fail to describe these ultra-long-range correlations. The results challenge existing paradigms and question the underlying mechanisms in low-multiplicity pp and p-Pb collisions. The findings impose significant constraints on models describing collective phenomena in small collision systems and advance the understanding of origin of long-range correlations at Large Hadron Collider (LHC) energies
Wafer-scale AA-stacked hexagonal boron nitride grown on a GaN substrate
No full textInternational audienceThe stacking sequence of two-dimensional hexagonal boron nitride (hBN) is a critical factor that determines its polytypes and its distinct physical properties. Although most hBN layers adopt the thermodynamically stable AA′ stacking sequence, achieving alternative stacking configurations has remained a long-standing challenge. Here we demonstrate the scalable synthesis of hBN featuring unprecedented AA stacking, where atomic monolayers align along the c axis without any translation or rotation. This previously considered thermodynamically unfavourable hBN polytype is achieved through epitaxial growth on a two-inch single-crystalline gallium nitride wafer, using a metal–organic chemical vapour deposition technique. Comprehensive structural and optical characterizations, complemented by theoretical modelling, evidence the formation of AA-stacked multilayer hBN and reveal that hBN nucleation on the vicinal gallium nitride surface drives the unidirectional alignment of layers. Here electron doping plays a central role in stabilizing the AA stacking configuration. Our findings provide further insights into the scalable synthesis of engineered hBN polytypes, characterized by unique properties such as large optical nonlinearity
Switchable Behavior and Applications of Low‐Dimensional Halide Perovskites under External Environmental Stimuli
No full textInternational audienceThe flexibility and adaptability of low‐dimensional halide perovskites make them ideal candidates for a wide range of cutting‐edge technologies. In addition to their primary applications in photovoltaics, they have recently attracted attention for their potential use in switchable technologies such as smart windows, encrypted messages, and sensors. The interest stems from their switchable properties, which enable them to change their physical properties, in particular photoluminescence and crystal color, in response to external stimuli such as heat, light, pressure, and humidity. This review examines their switchable properties and explores their practical applications in a number of emerging chromic technologies. This paper also provides an in‐depth analysis of the reversibility, switchable optical and electrical properties of low‐dimensional halide perovskites, and the switching mechanisms involved in the transformations they undergo. In addition, the paper is classified according to different switching mechanisms. To assist the research community in developing new designs for new switchable low‐dimensional perovskites, some basic criteria for effective switching materials are outlined here. Finally, the current challenges facing these emerging materials are discussed, and an outlook on future developments and potential breakthroughs in this promising area of research is provided
