HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
Not a member yet
13939 research outputs found
Sort by
Shaping of CO2 adsorption MOF materials in porous sheets: structure/properties/performance relationship
No full textNational audienc
Modelling pinching dynamics in thin films of binary mixtures
No full textInternational audienceIn binary mixtures, the lifetimes of surface bubbles can be five orders of magnitude longer than those in pure liquids because of slightly different compositions of the bulk and the surfaces, leading to a thickness-dependent surface tension of thin films. Taking advantage of the resulting simple surface rheology, we derive the equations describing the thickness, flow velocity and surface tension of a single liquid film, using thermodynamics of ideal solutions and thin film mechanics. Numerical resolution shows that, after a first step of tension equilibration, the Laplace-pressure-driven flow is associated with a flow at the interface driven by an induced Marangoni stress. The resulting parabolic flow with mobile interfaces in the film further leads to its pinching, eventually causing its rupture. Our model paves the way for a better understanding of the rupture dynamics of liquid films of binary mixtures
Biobased styrene copolymers prepared from mixtures of molecules fromlignin depolymerization
No full textInternational audienc
The Grotte du Bison Neandertals (Arcy-sur-Cure, France)
No full textInternational audienceThe Grotte du Bison, in Arcy-sur-Cure (Yonne, France), yielded a large assemblage of 49 Neandertal remains from late Mousterian layers, offering critical insights for the study of Middle to Upper Paleolithic populations of Western Europe. Previous studies described the external morphology of 13 isolated teeth and a partial maxilla. Building on this previous work, the current study provides further descriptions and analyses of the remains, including one postcranial fragment, six cranial fragments, two maxillary fragments, and 40 isolated teeth. The dental remains are examined for a more detailed assessment of the metric and nonmetric variability of their external and internal morphologies. We focus our description on preservation, health status, and age at death, and we assess the minimum number of individuals. The dental variability is also compared to that of Middle and Upper Pleistocene hominins. Our results indicate that the collection represents at least nine to 17 individuals, comprising mostly children and adolescents. Five to seven pairings are identified based on shared dental traits, developmental criteria, such as perikymata and pitted hypoplasia, wear patterns, and taphonomic alterations. This collection exhibits characteristic Neandertal features, including occasionally markedly expressed traits (e.g., I1 and P3 ridging and tubercular expressions), as well as a homogenous expression of accessory structures (particularly for the molars). The highest morphological variability is observed on maxillary premolar roots, which display different stages of root fusion, mesially placed hypercementosis, and pulp cavity extension. This collection also reflects the morphological and behavioral diversity observed in the other Arcy-sur-Cure caves
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
Atomic Force Microscopy Reveals Differences In Mechanical Properties Linked To Cortical Structure In Mouse And Human Oocytes
No full textInternational audienceCell mechanical properties regulate biological processes such as oocyte development. Cortical tension is regulated via actomyosin cortex remodeling to ensure optimal oocyte quality. However, the evolution of other mechanical parameters and their relationship with cortex structure remain poorly understood in mammalian oocytes. In this work, a methodology combining multiple mechanical parameters measured through Atomic Force Microscopy is proposed to investigate the relationship between oocyte mechanical properties and cortex organization. By studying mouse oocytes at various stages of development, along with engineered ones with specific cortex organization, it is demonstrated that a thin actin cortex corresponds to stiff oocytes while a thick one is associated with softer oocytes. It is further revealed that maternal age, a critical factor for fertility, affects mouse oocytes mechanics, correlating with alterations in their cortex structure. Finally, it is shown that the evolution of mechanical properties differs between human and mouse oocyte development, highlighting species-specific differences in cortex organization
Morphogenèse des fleurs de fromage par raclage
No full textInternational audienceThe “Tête de moine” Swiss cheese is generally served by scraping the surface of a cylindrical loaf with a sharp tool. This produces thin sheets of cheese that are strongly wrinkled at the edge, resembling frilly flowers and enhancing the tasting experience. In this work we unveil the physical mechanisms at play in this scraping-induced morphogenesis. We measure the deformation of the cheese during scraping and show that plastic deformation occurs everywhere, but find a larger plastic contraction in the inner part of the flower, causing its buckling into shape. We show that it surprisingly derives from the lower friction coefficient evidenced on the cheese close to its crust. Our analysis provides the tools for a better control of chip morphogenesis through plasticity in the shaping of other delicacies, but also in metal cutting. The new shaping mechanism evidenced here (inhomogeneous plastic shrinking induced by scraping) is described in its generality. It can be of interest for other materials such as in metal cutting or for polymer materials, when presenting inhomogeneous properties either by formulation, aging or mechanical processing. Even for homogeneous materials, the fact that friction properties control the metric change is also particularly interesting for material shaping: starting from a simple homogeneous material, but with a blade designed with spatially varying frictional properties~\cite{aymard2024designing}, these results open the possibility of programming complex shaping from a simple scraping process
Operando Photoemission Imaging of the Energy Landscape from a 2D Material-Based Field-Effect Transistor
No full textInternational audienceAs the integration of transition metal dichalcogenides (TMDC) becomes more advanced for optoelectronics, it is increasingly relevant to develop tools that can correlate the structural properties of the materials to their electrical output. To do so, the determination of the electronic structure must go beyond the hypothesis that the properties of the pristine material remain unaffected after device integration, which generates changes in the dielectric environment, including electric fields that are likely to renormalize the electronic spectrum. Here, we demonstrate that nanobeam photoemission spectroscopy is a well-suited tool to unveil the device energy landscape under operando conditions. Both the gate-induced vertical field and the drain in-plane vectorial electric field can be determined with a sub µm resolution. We conduct a correlative description of a field effect transistor, to connect its bias-modified energy landscape with transistor electrical output. The method appears highly suited to unveil how the actual geometry of the flake (thickness, edge effect, presence of structural defects…) is driving the current flow within the device. Lastly, the method appears fully compatible with traditional fabrication for devices, therefore making it relevant for systematic rational optimization of TMDC-based electronic devices
Molecular adsorption induces normal stresses at frictional interfaces of hydrogels
No full textInternational audienceFriction experiments were conducted on hydrogel thin films sliding against a rigid sphere in a low velocity regime where molecular adsorption at the sliding interface sets the friction force, through a dissipative adsorption-stretching-desorption mechanism initially postulated by Schallamach. By carefully imaging the contact from the initial indentation step of the sphere into the hydrogel to steady state sliding, we evidence for the first time that this very same adsorption mechanism also results in a normal force embedding the sphere further into the hydrogel. Observations of this tangential-normal coupling is made on a variety of chemically modified silica spheres, over 3 decades in velocity and at varied normal loads, thereby demonstrating its robustness. Quantitative measurements of the extra normal force and of the friction-velocity relationship versus normal load are well rationalized within a theoretical model based on the thermal actuation of molecular bonds. To do so, we account for the finite non-zero thickness of the sliding interface at which molecular adsorption and stretching events produce an out-of-plane force responsible for both friction and normal adhesive-like pull-in
Stability and Mitochondrial Localization of a Highly Cytotoxic Organogold(III) Complex with Diphosphine Ancillary Ligand in Lung Cancer Cells
No full textInternational audienceWe present a comprehensive study on the chemical reactivity in gas phase, with amino acids and peptides and in cell, the anticancer activity and localization of a series of seven cationic biphenyl gold(III) complexes with aryl, alkyl and chiral diphosphine ancillary ligands. Despite some structural differences, all the complexes similarly featured high stability toward reduction or ligand exchange in cell‐free conditions. The biphenyl Au(III) complex including the 1,2‐diphenylphosphinoethane (dppe) ligand manifested the same high stability in cellular setting, as attested by a combination of cryo‐Synchrotron Radiation‐X‐Ray Fluorescence (cryo‐SR‐XRF) nano‐imaging and cryo‐Synchrotron Radiation‐X‐ray Absorption Spectroscopy (cryo‐SR‐XAS) measurements. Tandem cryo‐SR‐XRF elemental mapping and confocal fluorescence microscopy demonstrated the selective accumulation of the dppe complex in mitochondria. This represents the first study of the speciation and distribution of an organogold(III) complex in cancer cells