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In the context of calling for low carbon emissions, lithium-ion batteries (LIBs) have been widely concerned as a power source for electric vehicles, so the fundamental science behind their manufacturing has attracted much attention in recent years. Calendering is an important step of the LIB electrode manufacturing process, and the changes it brings to the electrode microstructure and mechanical properties are worth studying. In this work, we reported the observed cracking of active material (AM) particles due to calendering pressure under ex situ nano-X-ray tomography experiments. We developed a 3D-resolved discrete element method (DEM) model with bonded connections to physically mimic the calendering process using real AM particle shapes derived from the tomography experiments. The DEM model can well predict the change of the morphology of the dry electrode under pressure, and the changes of the applied pressure and porosity are consistent with the experimental values. At the same time, the model is able to simulate the secondary AM particles cracking by the fracture of the bond under force. Our model is the first of its kind being able to predict the fracture of the secondary particles along the calendering process. This work provides a tool for guidance in the manufacturing of optimized LIB electrodes.

Water pollution by heavy metals is a problem of both western and developing countries. Heavy metal pollution can be associated to human activity, such as wastewaters from processing of ore mining, but also to simple contamination from metal rich soils. Whichever the case, chemical and physical methods are generally employed to depollute water. Since most chemicals are themselves polluting agents, there is an increasing interest in finding biobased and biodegradable alternative chemicals, both efficient in removing metals and benign to the environment. Biosurfactants are green chemicals produced by fermentation of yeasts and bacteria and with a good environmental score. Among many applications, this class of compounds has been used to remove heavy metals from contaminated soils. Within this framework, we propose a new mechanism of depolluting water using a glucolipid biosurfactant, G-C18:1, composed of glucose (G) and a C18:1 fatty acid (oleic acid). This compound is able to form a metallogel by complexing cations in water, thus trapping heavy metals (Cu 2+ , Ni 2+ , Cr 2+ and Co 2+) in the gel phase. This mechanism allows to remove up to 95% for cobalt and 88 ± 10%, 80 ± 3% and 59 ± 6% for Cu 2+ , Ni 2+ and Cr 2+ , respectively. A dedicated structural study shows that this is possible because positively charged species induce gelation of G-C18:1 through a micelle-to-wormlike phase transition, most likely driven by a charge neutralization process. This work shows that wise control of the nanoscale properties of green chemicals can strongly benefit to develop a sustainable future.

International audience; Nacre, also called mother-of-pearl, is a naturally occurring biomineral, largely studied by chemists, structural biologists, and physicists to understand its outstanding and diverse properties. Nacre is constituted of aragonite nanograins surrounded by organic matrix, and it has been established that the organic matrix is responsible for initiating and guiding the biomineralization process. The first challenge to study the organic matrix of nacre lays in its separation from the biomineral. Several extraction methods have been developed so far. They are categorized as either strong (e.g., decalcification) or soft (e.g., water, ethanol) and they allow specific extractions of targeted compounds. The structure of the nacreous organic matrix is complex, and it provides interesting clues to describe the mineralization process. Proteins, sugars, lipids, peptides, and other molecules have been identified and their role in mineralization investigated. Moreover, the organic matrix of nacre has shown interesting properties for human health. Several studies are investigating its activity on bone mineralization and its properties for skin care. In this review, we focus on the organic constituents, as lipids, sugars, and small metabolites which are less studied since present in small quantities.

International audience; This contribution aims to define an analysis procedure for abnormal deposits in human tissues starting from in vivo characterization, down to the nanoscale using major instrumentation. Such an integrated approach is based on recent literature, but particularly on our research over the last twenty years on pathological calcifications. To this end, we begin by describing four successive analytical steps, on the injury site or physician’s surgery, at the hospital, at a typical physicochemical laboratory, and finally at a large scale (possibly multinational) facility. For the first step, we present various techniques which can be implemented on portable instruments. For the second step, commercial analytical setups are used. In a physicochemical laboratory, prototype or commercial setups are used and finally on large scale instruments, characterization techniques with better spatial resolution and/or higher sensitivity or techniques specific to synchrotron radiation are employed.

International audience; Polyacid-functionalized inorganic mesoporous materials have attracted considerable interest as catalysts, permselective molecular sieves or drug carriers. Despite their great interest, their synthesis into ordered mesostructures incorporating polyacids densely and homogeneously distributed in the mesopores, is a challenge. Moreover, their properties as conductors for energy applications remain completely unexplored. Here we report an efficient, one-shot environmentally friendly synthesis route to prepare ordered mesoporous silica functionalized with strong polyacids, which exhibits excellent proton conductivity. We used polyion electrostatic complex micelles as structure-directing, functionalizing and pore-generating agents to obtain a material of remarkable textural and functional quality. It presents large and ordered mesopores hosting monodisperse polyacid chains corresponding to a dense and homogeneous functionalization of 1.2 mmolSO 3 H.gSiO 2-1 and a function density of 1 SO3H per nm 3 of mesopore volume. Overcoming the performance-limiting inhomogeneities, we designed a superprotonic conductor, while the high value of the conductivity, 0.024 S cm-1 at 363 K/95% relative humidity, was maintained at least 7 days.

International audience; The formation of 2:1 and 1:1 phyllosilicates in Fe–Si–O–H systems occurs in various geological and engineering settings; however, the identification and characterization of these minerals is very challenging due to the limited amount that is accessible, the very small particle size, and often the large degree of heterogeneity of these samples. To overcome these drawbacks, the synthesis of iron-rich phyllosilicates was attempted in this study with an initial Fe/Si molar ratio ranging from 0.50 to 2.33. The synthesis was performed at 150°C under hydrothermal conditions over a period of 7 days. Synthesis products were characterized by X-ray diffraction and fluorescence, by infrared, Raman, and Mössbauer spectroscopies, and by transmission electron microscopy. Results revealed that the stability field of the 2:1 clay mineral was wider than that of the 1:1 clay mineral. The 2:1 clay mineral was less sensitive to redox conditions compared to the 1:1 clay mineral. In addition, a heterogeneity of phases formed (iron oxides, nontronite, cronstedtite, or greenalite) was identified.

In this work different variables that can affect the catalytic behavior of CuO-CeO2 supported on mesoporous silica (SBA-15 and SBA-16) were studied. The influence on the COPrOx activity of the relative concentration of the CuO and CeO2 active phase and different impregnation methods in mesoporous support was analyzed. The physicochemical characterization was performed EDS-SEM and TEM-STEM, N2 isotherms, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The incipient wetness impregnation method (IWI) was the better alternative to introduce the active phases compared to solid state impregnation (SSI). In addition, the catalysts based on 2-D structure of SBA-15 were more active and selective than those based in 3-D SBA-16. In general, the high surface area of the supports benefited the dispersion of CuO and CeO2 oxides nanoparticles. All catalysts displayed the preservation of the mesostructure and the formation of nanoparticles of active phases (less than 10 nm) detected by TEM. The best COPrOx catalyst, obtained from the SBA-15 fibers by IWI method, with a relative CuO concentration of 0.2, exhibited XCO ≥ 99% at 175 °C and above 90% in a wide window of temperatures. This catalyst showed an adequate performance in presence of CO2 and H2O and good recovery of CO conversion and selectivity. The analysis by XPS revealed that the majority species were Ce4+, however in some catalysts Ce3+ species are also present, which are associated with vacancies oxygen and favor the redox process. In addition, Cu2+ and Cu+ species are present, the latter recognized as a key site of CO adsorption in the reaction mechanism.

Ultrafast laser processing can induce surface nanostructurating (SNS) in most materials with dimensions close to the irradiation laser wavelength. In-situ SNS characterization could be key for laser parameter's fine-tuning, essential for the generation of complex and/or hybrid nanostructures. Laser Induced Periodic Surface Structures (LIPSS) created in the ultraviolet (UV) range generate the most fascinating effects. They are however highly challenging to characterize in a non-destructive manner since their dimensions can be as small as 100 nm. Conventional optical imaging methods are indeed limited by diffraction to a resolution of ≈ 150 nm. Although optical super-resolution techniques can go beyond the diffraction limit, which in theory allows the visualization of LIPSS, most super-resolution methods require the presence of small probes (such as fluorophores) which modifies the sample and is usually incompatible with a direct surface inspection. In this paper, we demonstrate that a modified label-free Confocal Reflectance Microscope (CRM) in a photon reassignment regime (also called re-scan microscopy) can detect sub-diffraction limit LIPSS. SNS generated on a titanium sample irradiated with a λ =257 nm femtosecond UV-laser were characterized with nanostructuring period ranging from 105 nm to 172 nm. Our label-free, non-destructive optical surface inspection was done at 180µm²/s, and the results are compared with commercial SEM showing the metrological efficiency of our approach., L'interaction entre un laser ultrarapide et une objet peut induire une nanostructuration de surface (NSS) dans la plupart des matériaux, avec des dimensions proches de la longueur d'onde du laser d'irradiation. La caractérisation de NSS in-situ pourrait être la clé permettant un réglage fin des paramètres lasers, essentiel pour la génération de nanostructures complexes et/ou hybrides. Les structures de surface périodiques induites par laser (LIPSS) générées par une illumination ultraviolette (UV) génèrent les effets les plus fascinants. Ils sont cependant très difficiles à caractériser de manière non destructive puisque leurs dimensions descendre à 100 nm. Les méthodes d'imagerie optique classiques sont en effet limitées par la diffraction à une résolution de ≈ 150 nm. Bien que les techniques de super-résolution optique puissent aller au-delà de la limite de diffraction, ce qui permet en théorie la visualisation de LIPSS, la plupart des méthodes de super-résolution nécessitent la présence de petites sondes (comme des fluorophores) qui modifient l'échantillon et sont généralement incompatibles avec une imagerie directe des surfaces. Dans cet article, nous démontrons qu'un microscope confocale en réflectance sans marquage (CRM) dans un régime de réallocation de photons (également appelé microscopie de re-scan) peut détecter des LIPSS spis la limite de diffraction. Les NSS générées sur un échantillon de titane irradié avec un laser UV femtoseconde λ = 257 nm ont été caractérisés avec une période de nanostructuration allant de 105 nm à 172 nm. Notre inspection de surface optique sans marquage et non destructive a été effectuée à 180 µm²/s, et les résultats sont comparés avec un MEB commercial montrant l'efficacité métrologique de notre approche.

Cuprous oxide materials are of growing interest for optoelectronic devices and were produced by several chemical and physical methods. Here, we report on the structural, optical, and electrical properties of CuxO thin films prepared by the pulsed laser deposition technique. The substrate temperature, as well as the oxygen partial pressure in the deposition chamber, were varied to monitor the copper to oxygen ratio within the deposited films. The growth conditions were carefully optimized to provide the highest conductivity and mobility. Thus, 100 nm thick cuprous oxide films (Cu2O) deposited at 750 °C exhibited a resistivity of 16 Ω∙cm, high mobility of 30 cm2/(V∙s), and a bandgap of around 2 eV. The film deposited at the optimized deposition parameters on Nb:STO (001) substrate with Au top electrode showed a photovoltaic response with an open circuit voltage of 0.56 V. These results path the way to efficient solar cells made with Cu2O films via the pulsed laser deposition technique.

The capability to finely tailor material thickness with simultaneous atomic precision and non-invasivity would be useful for constructing quantum platforms and post-Moore microelectronics. However, it remains challenging to attain synchronized controls over tailoring selectivity and precision. Here we report a protocol that allows for non-invasive and atomically digital etching of van der Waals transition-metal dichalcogenides through selective alloying via low-temperature thermal diffusion and subsequent wet etching. The mechanism of selective alloying between sacrifice metal atoms and defective or pristine dichalcogenides is analyzed with high-resolution scanning transmission electron microscopy. Also, the non-invasive nature and atomic level precision of our etching technique are corroborated by consistent spectral, crystallographic and electrical characterization measurements. The low-temperature charge mobility of as-etched MoS$_2$ reaches up to $1200\,$cm$^{2}\cdot$V$^{-1}\cdot$s$^{-1}$, comparable to that of exfoliated pristine counterparts. The entire protocol represents a highly precise and non-invasive tailoring route for material manipulation., 46 pages, 4 figures, with SI

International audience; Aggregates of charged metal particles obtained by electrostatic coupling with a compound of opposite charge in the vicinity of the net zero charge ratio are of interest in the field of plasmonics because the inter-particle distance is minimal, which favours plasmonic coupling. However, these structures present a low colloidal stability limiting the development of applications. In this article we show that globally neutral aggregates formed by electrostatic complexation of citrate-stabilized gold particles and a quaternized chitosan (i.e., polycation) around the net zero charge ratio could be stabilized at a nanometric size by the subsequent addition of polyelectrolyte chains. Furthermore, the sign of the charge carried by the stabilizing chains determines the sign of the global charge carried by the stabilized complexes. The stabilization is demonstrated in saline environment on a broad pH range as well as in a cell culture media over periods of several days. Contrarily to stabilization by charged particles, our stabilized complexes are found to retain their initial characteristics (i.e. shape, size, internal structure and optical properties) after stabilization. Hence, the plasmonic coupling allows to maximize the optical absorption around the 800 nm wavelength at which the lasers used for thermoplasmonic and surface enhanced Raman scattering analysis operate.

National audience

International audience; Chromium coated zirconium based nuclear fuel claddings are among the most promising evolutive concepts in the field of Enhanced Accident Tolerant Fuel (EATF) developments [1-2]. The development of these new claddings has been accelerated since 2011 and the Fukushima-DAICHI nuclear accident. Among some other objectives, one of the main ideas is to develop new concepts of nuclear fuel claddings able to delay the High Temperature (HT) steam oxidation kinetics and the associated hydrogen production (explosion risk) and to improve the resultant Post-Quenching (PQ) cladding strength and ductility upon and following hypothetical accident conditions such as Loss-of-Coolant-Accident (LOCA). In this context, Cr-coated Zr based alloys, with 10-20µm thick Cr coating (PVD deposition), show promising behaviour .

Research efforts on the low temperature magnetic order and electronic properties of U$_3$O$_8$ have been inconclusive so far. Reinterpreting neutron scattering results, we use group representation theory to show that the ground state presents collinear out-of-plane magnetic moments, with antiferromagnetic coupling both in-layer and between layers. Charge localization relieves the initial geometric frustration, generating a slightly distorted honeycomb sublattice with N\'eel order. We show, furthermore, that spin-orbit coupling has a giant effect on the conduction band states and band gap value. Our results allow a reinterpretation of recent optical absorption measurements., Comment: 12 pages, including supplemental material

This thesis work aims to contribute to the development of new fiber sources emitting over a wide range of wavelengths in the IR, in particular to detect greenhouse gases in the mid-infrared range. Our spectroscopy results with nitrous oxide N2O and methane CH4 are obtained in band III. To achieve this, the generation of supercontinuum (SC) covering band III was made possible by using chalcogenide optical fibers, purified and free of highly toxic elements according to REACH regulations, in particular arsenic and antimony. The fibrable vitreous composition belonging to the Ge-Se-Te ternary system fits perfectly into the context of sustainable development, it is the one that has been identified and developed in the ICB laboratory. The setting up of experimental setups with different femtosecond sources was carried out in order to generate a supercontinuum covering the interval between 8 µm and 12 µm, belonging to the third band of atmospheric transparency. The optimization of many experimental parameters led to obtaining a wide supercontinuum from 1.7 µm to 18 µm with 40 dB of dynamic range, the fiber being pumped with a non-collinear optical parametric amplifier. Other non-fibered and fibered sources have made it possible to achieve original results concerning SCs with our step-index fibers and three-hole suspended core fibers. This led to the development of gas spectroscopy experiments. Several setups with different gas cells have been made with different sources, leading to important results. Nitrous oxide and methane have both been detected at wavelengths little explored so far, around 8 µm. The best experimental configuration led, with the supercontinuum emitted by a Ge-Se-Te fiber, to the detection of 14 ppm of methane when the fiber is pumped by an optical parametric oscillator. Detection goes down to 11 ppm of this gas if the Ge-Se-Te fiber is pumped by a fiber source., Ces travaux de thèse ont pour objectif de contribuer au développement de nouvelles sources fibrées émettant sur une large plage de longueurs d’ondes dans l’IR, en particulier pour détecter des gaz à effet de serre dans le domaine du moyen infrarouge. Des résultats de spectroscopie avec du protoxyde d’azote N2O et du méthane CH4 ont été obtenus dans la bande III. Pour y parvenir, la génération de supercontinuum (SC) couvrant la bande III a été rendue possible en employant des fibres optiques chalcogénures, purifiées et exemptes d’éléments fortement toxiques d’après la réglementation REACH, notamment l’arsenic et l’antimoine. La composition vitreuse fibrable appartenant au système ternaire Ge-Se-Te s’inscrit parfaitement dans le contexte du développement durable, c’est celle qui a été identifiée et développée au laboratoire ICB. La mise en place de montages expérimentaux avec différentes sources femtosecondes a été réalisée de façon à générer un supercontinuum couvrant l’intervalle compris entre 8 µm et 12 µm, appartenant à la troisième bande de transparence atmosphérique. L’optimisation de nombreux paramètres expérimentaux a mené à l’obtention d’un supercontinuum large de 1,7 µm à 18 µm avec 40 dB de dynamique, la fibre étant pompée avec un amplificateur paramétrique optique non-collinéaire. D’autres sources non fibrées et fibrées ont permis d’atteindre des résultats originaux concernant les SC avec nos fibres à saut d’indice et à cœur suspendu trois trous. Cela a conduit à développer des expériences de spectroscopie de gaz. Plusieurs montages avec différentes cellules de gaz ont été réalisés avec différentes sources, menant à d’importants résultats. Le protoxyde d’azote et le méthane ont été détectés à des longueurs d’onde peu explorées jusqu’à présent, vers 8 µm. La meilleure configuration expérimentale a conduit, avec le supercontinuum émis par une fibre Ge-Se-Te, à la détection de 14 ppm de méthane lorsque la fibre est pompée par un oscillateur paramétrique optique. La détection descend jusqu’à 11 ppm de ce gaz si la fibre Ge-Se-Te est pompée par une source fibrée.

Uranium dioxide (UO2) is the main component of nuclear fuels. This compound is very susceptible to oxidation, which results in the formation of the mixed-valence oxide U3O8. [1] From an application point of view, this interest relates to the safe and sustainable management of nuclear fuel. Our goal is an understanding of this oxidation process at the atomic level, using ab initio electronic structure calculations. The focus of this work lies in the early oxidation of stoichiometric UO2, where excess oxygen can be treated as interstitial point defects. In order to study this oxidation we investigate the adsorption of the O atom and oxygen-containing molecules (O2, H2O, H2O2) on the three most stable UO2 surfaces ((111), (110), and (100)). The calculations are performed within DFT, using PBE+U including spin-orbit coupling and taking into account the non-collinear 3k (transverse) magnetic ground state. Dissociative adsorption is found for H2O and H2O2 on the (111) and (100) UO2 surfaces respectively, forming hydroxyl groups on the surface. Adsorption on the UO2 surface lowers the barrier for the dissociation of O2. The defect formation energy is calculated for interstitial oxygen, up to several layers into the material starting from the surface. Additionally, adsorption energies are studied as a function of temperature and partial pressure.

International audience; Lithium molybdate single crystals up to one kilogram have been grown by a conventional Czochralski process. The growth configuration (geometry, coil, crucible, insulation casing) was optimized by numerical simulation of heat and mass transfer. Dislocations are shown to belong to the basal glide system. Their density (≤ 10 4 cm-2) and luminescence properties indicate crystal quality similar to that of previously reported crystals grown by Czochralski technique. Numerical simulation of thermo-elastic stresses suggest that the crack observed in one of these crystals is rather due to a mechanical accident than to internal stresses during growth.

Supramolecular peptide-based hydrogels attract great attention in several fields, i.e., biomedicine, catalysis, energy, and materials chemistry, due to the noncovalent nature of the self-assembly and functional tunable properties defined by the amino acid sequence. In this work, we developed an injectable hybrid supramolecular hydrogel whose formation was triggered by electrostatic interactions between a phosphorylated tripeptide, Fmoc-FFpY (F: phenylalanine, pY: phosphorylated tyrosine), and cationic polymer nanoparticles made of vinylimidazole and ketoprofen (poly(HKT-co-VI) NPs). Hydrogel formation was assessed through inverted tube tests, and its fibrillary structure, around polymer NPs, was observed by transmission electron microscopy. Interestingly, peptide self-assembly yields the formation of nontwisted and twisted fibers, which could be attributed to β-sheets and α-helix structures, respectively, as characterized by circular dichroism and infrared spectroscopies. An increase of the elastic modulus of the Fmoc-FFpY/polymer NPs hybrid hydrogels was observed with peptide concentration as well as its injectability property, due to its shear thinning behavior and self-healing ability. After checking their stability under physiological conditions, the cytotoxicity properties of these hybrid hydrogels were evaluated in contact with human dermal fibroblasts (FBH) and murine macrophages (RAW 264.7). Finally, the Fmoc-FFpY/polymer NPs hybrid hydrogels exhibited a great nitric oxide reduction (∼67%) up to basal values of pro-inflammatory RAW 264.7 cells, thus confirming their excellent anti-inflammatory properties for the treatment of localized inflammatory pathologies., Financial support from Spanish Research Council (CSIC) and French Research Council (CNRS) for the project PICS (International Emerging Actions) 2018 HYDROPRINT isgratefully acknowledged. The authors also acknowledge funding from CIBER-BBN, Spanish Ministry of Science, Innovation and Universities (MAT2017-83014-C2-2-P and MAT2017-84277-R), and the training program for Academic Staff, grant number FPU15/06109, of the Spanish Ministry of Education Culture and Sport.

International audience; Metal matrix nanocomposites encompassing low-melting point metal nano-inclusions are promising candidates for thermal regulation of devices at high temperature. They are usually processed by solid-state routes that provide access to a limited range of materials and are hardly compatible with complex shaping processes and with large-scale applications. Herein, we develop a liquid-phase processing technique to design aluminum matrix nanocomposites made of phase change nanoparticles, using bismuth nanoparticles as a proof-of-concept. The bismuth nanoparticles derived from colloidal chemistry are first encapsulated in a silica shell and then dispersed by ultrasonication into molten aluminum. Using X-ray diffraction, electron microscopy, and X-ray photoelectron spectroscopy, we probe the evolution of the bismuth particles and of the inorganic shell. We demonstrate that the silica shell acts as a barrier against extensive coalescence of particles during the dispersion process, thus enabling a decrease and a widening of the phase change temperature range.

International audience; The development of nanocomposite supramolecular hydrogels, which can be activated by local or external stimuli (pH, redox, enzyme, heat), is highly promising for various applications including implantable materials for antitumor or tissue engineering applications. Here, we show that large pore stellate mesoporous silica modified with isobutyramide grafts allow >100% wt. loading of enzymes, which ensures through the enzyme-assisted self-assembly an easy, rapid, and efficient way to design smart thermoresponsive nanocomposite supramolecular hydrogels. The typical temperature increase (42 °C), which may be induced by hyperthermia anticancer treatments, leads to the controlled-release of doxorubicin encapsulated in the resulting peptide self-assembled material.

International audience; The adaptability of hydrogels allows these structures to be used in a variety of industries, including biomedicine, soft electronics, and sensors.

International audience; We develop multidrug-loaded cubosome and spongosome lipid nanoparticles for targeting of endoplasmic reticulum stress as a potential emerging therapeutic strategy against neuronal degeneration. The multicompartment organization of the liquid crystalline nanoparticles (LCNPs), fabricated by self-assembly, was characterized by cryogenic transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS). Monooleinbased cubosome and spongosome LCNPs co-encapsulated the natural plant-derived antioxidant curcumin, fish oil rich in ω-3 polyunsaturated fatty acids (PUFA), and the neurotrophin brain-derived neurotrophic factor (BDNF), which is of vital need for neurogenesis. The neuroprotective properties of the nanoparticles were in vitro investigated in a cellular model of tunicamycin-induced endoplasmic reticulum (ER) stress using differentiated human neuroblastoma SH-SY5Y cells deprieved from serum. The intracellular accumulation of aggregates of misfolded proteins, typical for the ER stress process, was analyzed by fluorescence microscopy co-localization imaging and ER staining. The performed cellular bioassays established that the BDNF-loaded LCNPs enhanced the neuronal cell survival. The diminution of the tunicamycin-induced ER stress upon internalization of neuroprotective nanoparticles was quantified via the changes in the Thioflavin T fluorescence, which is a sensitive marker of protein aggregation. LCNPs with multi-drug loading appear to be promising candidates to face the challenges in neuroprotective nanomedicine development by exploiting ER-stress targeting mechanisms.

International audience; The worldwide massive production of plastics (368 Mt per year) and the poor recycling rate of wastes materials make them a scourge for the environmental. Waste storage in landfills and waste incineration are not sustainable solutions, as well as the mechanical recycling which gradually degrades the physical properties of plastic polymers. Chemical recycling, which is the depolymerization of materials into valuable monomers or chemicals, seems to be an appealing route for the future. Currently, well-known solvolysis processes catalyzed by bases, acids and ionic liquids enable the depolymerization of polymers by hydrolysis, aminolysis or transesterification reactions. They offer the recovery of pure monomers useful for the production of new virgin plastics. Recently, the reductive depolymerization processes have appeared as alternative approaches to access new value added products from plastics. The goal is to develop catalytic systems able to selectively cut and reduce polarized bonds (carbon-oxygen and/or carbon-nitrogen) of the polymers to obtain the corresponding monomers (alcohols, amines or hydrocarbons). Such reductive deconstruction methods are scarce and are all based on the use of H$_2$ or hydrosilanes as reductants. The catalytic hydrogenolysis of oxygenated and nitrogenated polymers (polyesters, polyamines and polyurethanes) was reported with Ru(II) and Ir(III) catalysts under high pressures and temperatures, whereas their catalytic hydrosilylations could take place under milder conditions with metal-based catalysts (Ir(III), Zn(II), Mo(VI)) or organocatalysts ([Ph$_3$C][B(C$_6$F$_5$)$_4$] and B(C$_6$F$_5$)$_3$). Hydroboranes as reductants could offer distinct reactivity and selectivity due to their higher hydride donor ability than hydrosilanes and an additional pronounced Lewis acidity. Inspired by the work of T. J. Marks et al., on the reduction of esters, we considered La[N(SiMe$_3$)$_2$]$_3$ as a 4f-catalyst and the pinalcolborane as a hydride donor, for the reductive depolymerization of a wide range of polyesters and polycarbonates.

International audience; The control of cell fate assisted by synthetic drug-delivering materials is still a challenging task for spatiotemporal regulation of bioactive molecules in native tissues. In this study, the potential of faujasite type (FAU) zeolites for delivering bioactive ions (i.e. Ca 2+ and Mg 2+) to pre-osteoblastic MC3T3-E1 cells is unveiled. Zeolites are porous aluminosilicates with a large surface area suitable for the storage of biologically active compounds. However, only a few studies have reported the use of zeolites in tissue engineering; therefore, this study aims to correlate the release profile of zeolites with the resulting cell functions. The textural properties of zeolites were assessed via MEB, BET, XRF, and EDX analyses. This study shows that either Mg-loaded (Mg-Y) or Ca-loaded (Ca-Y) zeolites are able to gradually release ions over up to three weeks in classical culture media in contrast to the burst release profiles often described in the literature. The ion concentration can be adjusted simply through the mass of zeolite added in the system and was quantified by colorimetric methods and capillary electrophoresis. Three zeolite concentrations were tested (i.e. 1, 1.5, and 3 wt%) for both ion types in order to span biologically relevant ranges (from 5.6 to 19.6 mM). The cell responses against various ionic strengths were evaluated not only by the reduction of resazurin assay for viability/proliferation assessment, but also through immunostainings and collagen secretions (Picrosirius red staining). The cell proliferation was found to be proportional to the Ca 2+ concentration whereas an upper limit seemed to have been reached for Mg 3% compared to Mg 1% and Mg 1.5%. Matrix secretions were delayed under conditions exposed to Ca 2+ relative to Mg 2+ after 7 days, but this trend reversed after 21 days. Overall, this study emphasizes the potential role of FAU as a simple, low cost, biocompatible, and versatile way to modulate the functions of MC3T3-E1 cells through ion delivery over up to three weeks. The ion concentration is correlated with the zeolite concentration, and the payload could be easily handled. Thus, this study will make it possible to broaden the applications of zeolites in tissue engineering which can also be implemented in multiple ways including surface coatings and nanocarriers.

International audience; In this work, a series of Type I photoinitiators (PIs) based on the naphthoquinone scaffold were designed and synthesized for the first time, in order to induce photopolymerization under visible light. As a result, these PIs exhibit excellent photoinitiation abilities in the presence of acrylates monomers upon LED@405 or @455 nm irradiation. Interestingly, some compounds have better photoinitiation performance than the benchmark Type I phosphine-oxide i.e. diphenyl(2,4,6trimethylbenzoyl)phosphine oxide (TPO) upon exposure to LED@455 nm. Chemical mechanisms supporting the photopolymerization process were investigated through different techniques as well as theoretical calculations. In addition, the new proposed structures were also investigated in two-component photoinitiating systems and exhibited a higher efficiency in free radical photopolymerization. Finally, direct laser write approach is successfully used to fabricate 3D objects.

International audience; Complementary tools to classical analytical methods, enzymatic biosensors are widely applied in medical diagnosis due totheir high sensitivity, potential selectivity, and their possibility of miniaturization/automation. Among the different protocolsof enzyme immobilization, the covalent binding and cross-linking of enzymes ensure the great stability of the developedbiosensor. Obtained manually by drop-casting using a specific cross-linker, this immobilization process is not suitable for thespecific functionalization of a single electrode out of a microelectrode array. In the present work, we developed a nanohybridenzymatic biosensor with high sensitivity by a mussel-inspired electro-cross-linking process using a cheap and abundantnatural molecule (tannic acid, TA), gold salt, and native enzymes. Based on the use of a cheap natural compound and goldsalt, this electro-crosslinking process based on catechol/amine reaction (i) is versatile, likely to be applied on any kind ofenzymes, (ii) does not require the synthesis of a specific cross-linker, (ii) give enzymatic biosensors with high and very stablesensitivity over two weeks upon storage at room temperature and (iv) is temporally and spatially controlled, allowing thespecific functionalization of a single electrode out of a microelectrode array. Besides the development of microbiosensors,this process can also be used for the design of enzymatic biofuel cells.

International audience; Limiting the serum protein fouling is a major challenge in the design of nanoparticles (NPs) for nanomedicine applications. Suitable chemical surface modification strategies allow to limit the interactions with adsorbing proteins. In this communication, we address the potential of isobutyramide (IBAM) groups grafted on stellate silica nanoparticles (STMS) for the immobilization of two biocompatible polymers renown for biomedical and low fouling applications: Hydroxypropylcellulose (HPC) and Pluronic F127 (PF127). We report that both polymers can be loaded on STMS@IBAM NPs surface with a maximum loading content close to 10 wt %. Regarding their antifouling properties, we report that the coatings of such HPC or PF127 polymers allow to reduce significantly the human serum albumin (HSA) adsorption in average by 70 % as compared to the surface of the free polymer STMS@IBAM. These results highlight the antifouling potential of these polymer pretreatments on IBAM-modified STMS NPs surface.

International audience; The Composite Ceramic Nuclear Liner project is part of the Cigéo project, a deep geological disposal facility for high-level and long-lived intermediate-level radioactive waste led by Andra, the French national agency for radioactive waste management. The concept of high level radioactive waste (HLW) disposal cells involves the installation of a liner consisting of a hollow cylinder inserted into a micro-tunnel dug into a clay formation. The main function of the liner is to allow the emplacement and the potential recovery of the HLW packages, during the entire period of reversible operation of the facility, estimated to be 100 years. The current preferred solution is a steel liner. However, corrosion of metals under anoxic conditions is likely to generate hydrogen. Among the potential areas of development of the disposal facility, Andra is studying alternative materials to metals for the liner. On top of the mechanical requirements already met by the metallic solutions identified, the new materials must be chemically inert with respect to the vitrified waste and the host rock [2].The objective of the feasibility assessment was to remove the technological barriers associated with the use of ceramic matrix composites (CMC) for the lining of HLW cells. It is an innovative application for materials initially developed for extreme temperatures applications. The project was divided into three parts: (i) literature study and characterization of commercial materials; (ii) in-situ conditions definition and structural analysis; (iii) production of a prototype and pre-industrial implementation. In the first step a state of the art was established and CMCs that could potentially meet the specific requirements of the HL cell liner have been preselected. These materials were of different nature, both in terms of reinforcements and matrix : Oxide/Oxide ; Carbon/Geopolymer (PyroKarb) and Oxide/Geopolymer (PyroXide) produced by the Pyromeral company ; Carbon/Carbon produced by the company Mersen - AW252 long fibres 2.5 D, A202 long fibres 2 D and A015 short fibres. In the second phase, a mechanical study was carried out on these potential materials [3] leading to a design of the liner architecture. Finally, proofs of concept were manufactured in order to validate {material/process} pairs.

International audience; Understanding mechanical properties and their microscopic origins is fundamental for multiple fields in condensed matter research. They are controlled by defects, dislocations, diffusion, as well as microstructures, which are not trivial to study under extreme conditions. This chapter summarizes the last 25 years of advances in high pressure devices, x-ray measurements, and data interpretation capabilities for addressing the deformation and plasticity of materials under extreme conditions, from experiments in large volume presses or diamond anvil cells, texture and stress analysis in powder x-ray diffraction, multi-grain crystallography, to self consistent models of materials behavior. Examples of applications are then provided in the fields of geophysics and materials science along with perspectives for studies of plastic deformation under extreme conditions in the coming years.

International audience; Débuté en 2019, le projet ANR Bigdad porte sur l'altération aqueuse des principaux produits verriers industriels mis sur le marché. Depuis quelques décennies la migration d'éléments constitutifs du contenant vers le contenu a été démontrée [1; 7], notamment dans le cas du cristal au plomb [4-6], pouvant conduire à une évolution de la réglementation concernant l'emploi des matières premières (REACh) et les limites de migration. Une partie du projet est présentée ici sur l'effet de différents traitements de surface sur la migration des éléments.Des essais normalisés [2; 3] proposent de retenir l'acide acétique comme milieu représentatif d'un contact alimentaire. Des tests de lixiviation à court et long terme (jusqu'à trois ans d'altération) ont été menés sur cinq compositions industrielles : borosilicate, cristallin au baryum, cristal au plomb, sodocalcique et fluorosilicate (aussi dit verre opale) pour déterminer les mécanismes d'altération propres à chaque verre. Des études structurales par RMN du solide haute résolution avant et après altération, ainsi que des caractérisations poussées par MEB-EDS et ToF SIMS ont été menées pour caractériser les couches d'altérations dont les épaisseurs s'échelonnent de quelques centaines de nanomètres à quelques dizaines de microns après trois ans d'altération.A partir de cette vue d'ensemble du comportement des verres au cours de leur altération en milieu acide, les effets de cinq traitements de surface ont été étudiés du point de vue de leur impact sur la durabilité des produits verriers. Trois traitements par dépôts chimiques ont été sélectionnés : oxyde d'étain (SnO2), oxyde de silicium (SiO2) et oxyde de titane (TiO2) et deux traitement par voie chimique : polissage acide et cémentation. L'ensemble de ces traitements ont été appliqués sur les cinq compositions de verre étudiées précédemment. Les cinétiques d'altération ont pu être collectées sur plus d'un an d'altération et les résultats montrent des effets qui peuvent être particulièrement bénéfiques vis-à-vis du relâchement de certains éléments. Références :1. Bunker, B.C. Molecular mechanisms for corrosion of silica and silicate glasses. Journal of Non-Crystalline Solids, 179, (1994), 300-308.2. Ceramic cookware in contact with food - Release of lead and cadmium -; and 1986. ISO 8391-1:1986.3. Glass hollowware in contact with food - Lead and cadmium emission -, 2019. ISO 7086:2019.4. Graziano, J.H.; and Blum, C. Lead exposure from lead crystal. The Lancet, 337, 8734 (1991), 141-142.5. Guadagnino, E.; Gramiccioni, L.; Denaro, M.; and Baldini, M. Co-operative study on the release of lead from crystalware. Packag. Technol. Sci., (1998), 13.6. Guadagnino, E.; Verita, M.; Geotti-Bianchini, F.; Shallenberger, J.; and Pantano, C.G. Surface analysis of 24% lead crystal glass articles: correlation with lead release. Glass Technology, 43, 2 (2002), 63-69.7. Sinton, C.W.; and LaCourse, W.C. Experimental survey of the chemical durability of commercial soda-lime-silicate glasses. Materials Research Bulletin, 36, 13-14 (2001), 2471-2479.

International audience; Le développement des matériaux composites pour des applications industrielles à grande échelle comme les époxy renforcés par des fibres de verre ou de carbone, posent problème au niveau environnemental. En effet, contrairement aux thermoplastiques, les polymères thermodurcissables utilisés comme matrice des composites sont difficiles à recycler. Dans une démarche visant une production plus écoresponsable des composites, la technique de moulage par transfert de résine (Thermoplastic Resin Transfer Molding – TP-RTM), appartenant à la famille des procédés « Liquid Composite Moulding », permet la production de composites à matrice thermoplastique. Une résine de faible viscosité est nécessaire afin de permettre une bonne imprégnation des fibres. Les mélanges de réactifs utilisés pour la production des composites à matrice thermoplastique peuvent être composés d’un ou plusieurs monomères associés à un catalyseur.[1] Le poly(L-lactide) (PLLA), un polymère biosourcé, biocompatible et biodégradable, est devenu un acteur majeur du marché en particulier pour des applications à courte durée de vie dans des secteurs tel que l’emballage ou le biomédical. A ce jour, l’emploi du PLLA pour des applications à longue durée de vie reste mineure. Ceci est principalement due à son faible allongement à la rupture et à sa faible résistance aux chocs, bien que sa contrainte à rupture soit proche de celle du polypropylène.[2] A l’inverse, la poly(E-caprolactone) (PCL), polymère également biodégradable et biocompatible, possèdeun allongement à la rupture cent fois supérieur au PLLA.[3] Dans ce contexte, i.e. afin d’améliorer les propriétés mécaniques en vue d’une utilisation pour des applications durables, de nouveaux composites à matrice poly(L-lactide-co-ε-caprolactone) (PLCL) renforcés par des fibres de verre ont été produits par TP-RTM (Figure 1). Ces matériaux inédits n’ontjamais été élaborés auparavant, même par les techniques conventionnelles de production de composite. La faible viscosité du mélange des réactifs a permis la production des composites avec une teneur en volume de renfort proche de 50 % et une mouillabilité quasi complète des fibres de verre. Les caractéristiques thermiques, morphologiques et les propriétés mécaniques de ces matériaux inédits seront présentées et discutées.

International audience; Les verres dits opales sont des verres industriels fluorosilicatés constitués d'une matrice vitreuse au sein de laquelle on fait germer et croître des cristaux à l'échelle plutôt nanométrique. Ces verres translucides à aspect blanc laiteux, sont à destination principalement des arts de la table. L'objectif de cette étude est d'évaluer la durabilité chimique de ces verres sur le long terme dans une solution d'acide acétique à 70°C, pendant environ 7,5 mois. L'acide acétique est le milieu retenu comme représentatif d'un contact alimentaire[1]. Cette étude s'inscrit dans le cadre plus large d'un projet ANR nommé Bigdad, portant sur l'altération aqueuse des principaux produits verriers industriels mis sur le marché en caractérisant les phénomènes de migration des éléments constitutifs du contenant vers le contenu. Les verres opales étudiés ont été extraits à partir d'assiettes. Deux surfaces distinctes ont été analysées : l'une lisse provenant de l'assiette côté air, l'autre rugueuse provenant de l'assiette côté moule de centrifugation. Deux variétés de verre ont été choisies : l'un avec une couche d'oxyde d'étain en surface, l'autre sans couche de SnO2.Trois techniques complémentaires ont été utilisées pour caractériser ces verres opales, à l'état sain et à l'état altéré, avec ou sans couche de SnO2 : la spectrométrie de masse d'ions secondaires à temps de vol (ToF-SIMS) qui permet des réaliser des profils d'analyse élémentaire et moléculaire sur la surface (dans cette étude jusqu'à 2,5 m de profondeur) ; la RMN multinucléaire pour sonder la structure locale de ces verres, quantifier les phases cristallines et aussi déterminer l'environnement local autour d'isotopes naturellement présents dans le verre (dans cette étude 29Si, 27Al, 19F et 23Na) ; la microscopie électronique en transmission avec système de microanalyse (ATEM), qui permet d'imager les nanocristaux présents dans les verres opales, et de caractériser texturalement et chimiquement les couches d'altération.Un bilan complet de ces analyses sera présenté, révélant notamment les corrélations entre les résultats obtenus par ces trois techniques de caractérisation et la durabilité chimique de ce type de verre. Références :1. Glass hollowware in contact with food - Lead and cadmium emission -, 2019. ISO 7086:2019.

International audience; The localized surface plasmon resonance (LSPR) of Au nanoparticles (NPs) was used to monitor photopolymerization at the nanoscale, by in situ monitoring the optical response of AuNPs during the light-induced polymerization process. To show the interest of this approach, two configurations were used which correspond to a resonant and a non-resonant excitation regime between the photopolymer and the AuNPs used as nanoprobes. We show that not only this method enables the progress monitoring of the photopolymerization reaction at the nanometric scale but also can highlight the near-field coupling effect responsible for the acceleration of the photoinduced reaction. This methodology appears very interesting to study the photoinduced nanofabrication processes of metal/polymer hybrid nanoparticles and more globally as a methodology to study the photopolymerization reactions at the nanometric scale.

International audience; This paper reports on the thermodynamics through mapping out temperature−concentration phase diagrams and the molecular structure and the morphology of binary organogels prepared with trisamide triarylamine (TATA) in tetrachloroethane and on their ternary thermoreversible hybrid gels formed with polyvinyl chloride (PVC). For low PVC contents, the TATA organogel moiety behaves as in the binary systems, while for higher PVC contents, the thermal behavior is significantly altered with the appearance of a nonvariant event. The molecular structure of the TATA assemblies is compared with that observed in the bulk solid state. Three molecular packings are observed in the bulk, whose crystalline lattices are tentatively derived. Structure I obtained after the crystallization−purification process is seen to transform at higher temperature into structure II. By cooling, structure III is obtained, which transforms reversibly into structure II on heating. The metastability of structure I leads one to contemplate the possible formation of molecular compounds during the crystallization− purification process in the presence of chlorinated solvents, the more so as the crystalline structures in the gels turn out to exhibit high similarities. Finally, the morphology observation reveals that the TATA fibrils and the PVC matrix can be well identified for low PVC contents, while for higher PVC contents, one essentially observes the TATA fibrils.

Ultrafast molecular dynamics in fluids is of great importance in many biological and chemical systems. Although such dynamics in bulk liquids has been explored by various methods, experimental tools that unveil the dynamics of solvated solutes are limited. In this work, we have developed resonant optical Kerr effect spectroscopy (ROKE), which is an analogue of optical Kerr effect spectroscopy that measures the reorientational relaxation of a dilute solute in solution. By adjusting the pump and probe wavelengths at the resonant absorption band of a solute, the time response of the solute was distinguished easily from the negligible signal of the solvent. The heterodyne detection of ROKE enables the determination of reorientational relaxation time constants with an accuracy of 2.6%. The signal-to-noise ratio was high enough (average ∼26.7) to obtain an adequate signal from even a 10 μM solution. Thus, ROKE is a powerful tool to study solute dynamics with high sensitivity in a broad range of applications.

National audience

International audience; This work presents the experimental study of the behavior of copper and copper oxides in presence of pollutants in steam generator flow-restricted areas. The experiments were conducted under secondary circuit thermochemical conditions. Two redox conditions were performed, reducing ones to reproduce operating conditions, with or without presence of magnetite, and a weakly oxidizing one to simulate an oxygen inlet. High concentrations of sodium and phosphates were used to simulate a heavily polluted environment that can be encountered in flow-restricted areas during hideout process.In a steam generator (SG) of a Pressurized Water Reactor (PWR), the hideout process can occur in flow-restricted areas. Non-volatile polluting species tend to accumulate in these regions due to boiling. Their concentrations can reach up to several orders of magnitude [1] above those encountered in the chemical conditioning yielding extreme pH values. Such pollutants include various metallic elements like iron, nickel, sodium, aluminum or copper, and other ions like sulfates, chlorides or phosphates. Some authors have already discussed the behavior of solid copper species in presence of phosphate under secondary circuit thermochemical conditions. Turner et al. [2] showed how sodium phosphate lead to aconsolidation of a magnetite-copper sludge already formed with few information on which phases were observed, and Ziemniak et al. [3] and Palmer [4] had a major focus on the dissolved species rather than the solids. This study is a step towards a more complete description of the flow-restricted areas, including the interaction of copper and copper oxides with other species present in the secondary circuit. The objective was to identify the stable solid copper-containing species under the thermochemical conditions encountered in SG flow-restricted areas

International audience; The use of postsynaptic current to drive long-lasting luminescence holds a disruptive potential for harnessing the next-generation of smart displays. Multiresponsive long afterglow emission can be achieved by integrating light-emitting polymers in electric spiked transistors trigged by distinct presynaptic signals inputs. Here, we report a highly effective electric spiked long afterglow organic light-emitting transistor (LAOLET), whose operation relies on a nanofloating gate architecture. Long afterglow emission with reconfigurable brightness and retention time is observed upon applying specific positive gate voltage spiked. Conversely, when negative gate voltage stimulus is applied, these LAOLETs function as click-on display. Interestingly, upon endowing the device with force sensing capabilities, it can operate as a long afterglow pressure sensor that emits long-lasting green light subsequently to a controlled extrusion action.

International audience

International audience; Engineered nanomaterials have been found to induce oxidative stress. Cellular oxidative stress, in turn, can result in the induction of antioxidant and detoxification enzymes which are controlled by the nuclear erythroid 2-related factor 2 (NRF2) transcription factor. Here, we present the results of a pre-validation study which was conducted within the frame of BIORIMA (“biomaterial risk management”) an EU-funded research and innovation project. For this we used an NRF2 specific chemically activated luciferase expression reporter gene assay derived from the human U2OS osteosarcoma cell line to screen for the induction of the NRF2 mediated gene expression following exposure to biomedically relevant nanobiomaterials. Specifically, we investigated Fe 3 O 4 -PEG-PLGA nanomaterials while Ag and TiO 2 “benchmark” nanomaterials from the Joint Research Center were used as reference materials. The viability of the cells was determined by using the Alamar blue assay. We performed an interlaboratory study involving seven different laboratories to assess the applicability of the NRF2 reporter gene assay for the screening of nanobiomaterials. The latter work was preceded by online tutorials to ensure that the procedures were harmonized across the different participating laboratories. Fe 3 O 4 -PEG-PLGA nanomaterials were found to induce very limited NRF2 mediated gene expression, whereas exposure to Ag nanomaterials induced NRF2 mediated gene expression. TiO 2 nanomaterials did not induce NRF2 mediated gene expression. The variability in the results obtained by the participating laboratories was small with mean intra-laboratory standard deviation of 0.16 and mean inter laboratory standard deviation of 0.28 across all NRF2 reporter gene assay results. We conclude that the NRF2 reporter gene assay is a suitable assay for the screening of nanobiomaterial-induced oxidative stress responses.

International audience; The goal of this poster presentation is to give an overview of nanofabrication techniques commonly used for the realization of nanostructures in our micro and nanofabrication facilities. We focus on the process equipment available in the CINaM clean room. We will also present some recent scientific results in photonics obtained on plasmonics nano-arrays for molecular sensing (collaboration with B. Demirdjian’s group) [1] and on transition metal dichalcogenide structures showing a non-linear coupling between excitons and Mie scattering resonances in the visible and near infrared spectral regions (collaboration with G. Tselikov) [2]. We will also present the fabrication of nanocluster arrays used for detection of hidden features in the architecture of T-lymphocyte cells (collaboration with K. Sengupta’s group) [3]. Finally, we will present our recent results on fabrication of sharp silicon arrays to wound Caenorhabditis elegans worms (collaboration with J.J. Ewbank’s group) [4].All micro and nanostructures were obtained in our clean room facilities using nanofabrication tools such as optical and electron beam lithography, magnetron sputtering or thermal evaporation and chemical or reactive ion etching.The PLANETE platform is open to the regional scientific research community as well as to innovative companies carrying out research and development projects. All the cleanroom facilities and equipment are available to them to carry out their projects with technical assistance from the platform staff according to their needs.[1] B. Demirdjian, I. Ozerov, F. Bedu, A. Ranguis, and C.R. Henry, ACS Omega 6, 13398 (2021)[2] A.A. Popkova et al. Laser & Photonics Reviews 16, 2100604 (2022)[3] A. Nassereddine et al. Nano Letters 21, 5606 (2022)[3] J. Belougne, I. Ozerov, C. Caillard, F. Bedu, J.J. Ewbank, Scientific Reports 10, 3581 (2020)

International audience; Lateral diffusion of nano-objects on lipid membranes is a crucial process in cell biology. Recent studies indicate that nanoparticle lateral diffusion is affected by the presence of membrane proteins and deviates from Brownian motion. Gold nanoparticles (Au NPs) stabilized by short thiol ligands were dispersed near a free-standing bilayer formed in a 3D microfluidic chip. Using dark-field microscopy, the position of single NPs at the bilayer surface was tracked over time. Numerical analysis of the NP trajectories shows that NP diffusion on the bilayer surface corresponds to Brownian motion. The addition of bovine serum albumin (BSA) protein to the solution led to the formation of a protein corona on the NP surface. We found that protein-coated NPs show anomalous superdiffusion and that the distribution of their relative displacement obeys Lévy flight statistics. This superdiffusive motion is attributed to a drastic reduction in adhesive energies between the NPs and the bilayer in the presence of the protein corona. This hypothesis was confirmed by numerical simulations mimicking the random walk of a single particle near a weakly adhesive surface. These results may be generalized to other classes of nano-objects that experience adsorption-desorption behaviour with a weakly adhesive surface.

International audience; Les verres nucléaires actuellement utilisés pour le confinement des produits de fission et actinides mineurs peuvent inclure un taux de charge allant jusqu'à 18.5%. Les matériaux vitrocéramiques envisagés pour cette application seraient une alternative intéressante qui permettrait de diminuer le volume de colis. Pendant le stockage, les inclusions de phases cristallines, riches en produits de fission, sont soumises à une auto-irradiation α provoquant un gonflement susceptible d'engendrer une fissuration de la matrice vitreuse. La mise en oeuvre de simulations de grande taille devra permettre d'évaluer l'effet de la microstructure sur la fissuration du matériau en se rattachant à des quantités d'intérêt comme le temps avant la première fissuration ou la surface fissurée. Pour répondre à cette question, on se propose de mettre en place une simulation numérique de la fissuration dans ce type de matériau. Les méthodes numériques s'appuyant sur l'utilisation des Transformées de Fourier Rapide (FFT en anglais), dites « méthodes FFT », sont particulièrement adaptées à la simulation du comportement mécanique de matériaux hétérogènes. En effet, comparés à l'utilisation de codes Élément-Finis « standards », les codes FFT sont souvent bien plus performants et très bien adaptés à une implémentation parallèle en mémoire distribuée. Initialement proposée pour des modèles de comportement locaux, linéaires ou non-linéaires, l'utilisation de ces méthodes s'étend désormais au cadre des modèles non-locaux, tels que la plasticité ou l'endommagement à gradient [4, 9]. Par ailleurs, pour simuler la fissuration, les modèles de champ de phase d'endommagement [6, 2] sont l'objet d'un intérêt croissant dans la communauté mécanicienne. Ainsi, l'implémentation du modèle de champ de phase proposé par Miehe [10] a été récemment proposée au sein de codes FFT [4, 5], et notamment au sein du code massivement parallèle AMITEX_FFTP [1]. L'objet de cette communication est donc de présenter les premiers résultats et améliorations mises en places pour l'étude des matériaux hétérogènes à inclusions gonflantes. La première partie de l'exposé se concentrera sur le cadre de comportements élastiques linéaires (avec gonflement des inclusions). Une attention particulière sera portée ici à l'utilisation de voxels composites [7, 8] afin d'améliorer la qualité des simulations numériques [3]. Les analyses seront réalisées dans un premier temps sur des cellules de taille réduite (une inclusion) puis sur des cellules plus larges avec une distribution aléatoire d'inclusions. On présentera ici brièvement les outils génériques développés au CEA pour générer les microstructures, les voxeliser et identifier les voxels composites. Enfin, ces simulations sur matériaux élastiques seront l'occasion d'analyser les performances du code AMITEX_FFTP en terme de scalabilité (faible et forte). La seconde partie de l'exposé sera consacrée aux premières simulations FFT de la fissuration de matériaux hétérogènes avec inclusion gonflante. Après avoir rappelé le modèle de Miehe [10] on présentera son implémentation au sein d'une méthode FFT et plus particulièrement au sein du code AMITEX_FFTP. Cette première implémentation repose sur l█utilisation d'une variable d'« histoire » visant à assurer une évolution croissante du champ de phase et, côté algorithme, sur un schéma alterné (non itératif), consistant à résoudre un problème de champ de phase, puis un problème de mécanique avant de passer au pas suivant. Ce type d█algorithme nécessite l█utilisation de pas de chargements très fin. Pour le traitement spécifique aux matériaux hétérogènes, l█approche retenue est celle proposée par Ernesti [5]. Enfin, on proposera ici différents choix de discrétisation spatiale des équations (des problèmes mécaniques et de champ de phase) et on discutera l█effet de ce choix sur les résultats de simulations. De même, l█effet positif de la prise en compte des voxels composites démontré pour des comportements linéaires sera discuté ici. Les analyses présentées seront réalisées sur des géométries simples ne considérant qu█une seule inclusion (disque en 2D, sphère en 3D).

International audience; Nowadays, phosphorescent organic light-emitting diodes (PhOLEDs) is a widespread technology, in which all the high-performance devices are constructed on a stack of different organic layers called multi-layer devices (ML-PhOLEDs). Thanks to these functional layers, the injection, the transport, and the recombination of holes and electrons in the emissive layer (EML) are significantly improved, allowing to reach high performances. In this technology, the ideal devices are the single-layer PhOLEDs (SL-PhOLEDs), with a very simple stack only constituted by the electrodes and the EML. These devices are simple, very easy to fabricate, and can hence significantly decrease their costs. Nevertheless, removing the functional layers of an OLED drastically decreases the performances and there is, so far, only a few examples of high-performance SL-PhOLEDs. Thus, in SL-PhOLEDs, the role of the functional layer should be performed by the EML, which should allow an excellent injection, transport, and recombination of holes and electrons. In this work, thanks to a rational molecular design of the EML, we report a green-emitting SL-PhOLED, displaying a very high external quantum efficiency of 22.7%. The EML of this device is constructed on the barely studied Ir(ppy)2acac phosphor and a high efficiency host material possessing a Donor-spiro-Acceptor design. This performance is, to the best of our knowledge, the highest reported to date for SL-PhOLEDs (all colors considered). Through a structure/property/device performance relationship study combining morphological (AFM), photophysical (time-resolved spectroscopy) and charge transport studies, we show that the EML presents all the required characteristics such as smooth surface, quick radiative deactivation, and ambipolarity. In addition, the comparison with Ir(ppy)3, the most famous green emitter used in PhOLEDs, highlights the high potential of Ir(ppy)2acac. The impact of the phosphorescent emitter on the ambipolarity of the charge transport is particularly evidenced.

International audience; Hierarchical porosity sol-gel monoliths (HPMs) are of increasing interest for a wide variety of applications due to their outstanding microstructural (homogenous) and textural properties (high porosity and specific surface area) [1]. The high flow rate and low-pressure resultant compared to conventional materials, makes them suited for extraction and enrichment of analytes of interest in analytical techniques (HPLC, SPE, etc.) [2–4]. However, pure inorganic materials have rarely been considered for relevant applications in various omics fields such as metabolomics or proteomics [5].In the context, we report on: (i) a pure silica HPM based on a finely tuned bimodal porosity thoroughly controlled, (ii) coupled to a new way to a miniaturize shaping (iii) and its use as an innovative tool for sample preparation prior to glycan analysis by mass spectrometry, as a new source of disease biomarkers (glycomics analysis). The monolith synthesis will be presented with a special emphasize on its robustness and on the modulations of the bimodal porosity obtained ([0.1–5] μm and [1-25] nm). Beside microstructural and textural properties measurements (SEM, Hg porosimetry, etc.), the transport of small molecules through mesoporous network were evaluated by TEM tomography. Finally, the material was processed in different shapes and size (50 μm – 4 mm in diameter) demonstrating a high flexibility of our approach to produce devices dedicated to a biological analysis. The use of HPM for the analysis of both free and protein-bound oligosaccharides present in precious samples (human blood and milk) and their detection by MALDI-TOF mass spectrometry will be presented as a proof of concept. Optimized experimental conditions, as well as material textures and shapes, enabled straightforward and time-efficient purification and MS- based glycomics analysis using minute quantities (few μl) of solvents but above all of complex human biofluids, thus outperforming common laboratory protocols.

International audience; Ultrasmall metal nanoclusters (NCs) are employed in an array of diagnostic and therapeutic applications due to their tunable photoluminescence, high biocompatibility, polyvalent effect, ease of modification, and photothermal stability. However, gold nanoclusters' (AuNCs') intrinsically antimicrobial properties remain poorly explored and are not well understood. Here, we share an insight into the antimicrobial action of atomically precise AuNCs based on their ability to passively translocate across the bacterial membrane. Functionalized by a hydrophilic modified-bidentate sulfobetaine zwitterionic molecule (AuNC-ZwBuEt) or a more hydrophobic monodentate-thiolate, mercaptohexanoic acid (AuNC-MHA) molecule, 2 nm AuNCs were lethal to both Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. The bactericidal efficiency was found to be bacterial strain-, time-, and concentration-dependent. The direct visualizations of the translocation of AuNCs and AuNC-cell and subcellular interactions were investigated using cryo-soft X-ray nano-tomography, transmission electron microscopy (TEM), and scanning TEM energy-dispersive spectroscopy analyses. AuNC-MHA were identified in the bacterial cytoplasm within 30 min, without evidence of the loss of membrane integrity. It is proposed that the bactericidal effect of AuNCs is attributed to their size, which allows for efficient energy-independent translocation across the cell membrane. The internalization of both AuNCs caused massive internal damage to the cells, including collapsed subcellular structures and altered cell morphology, leading to the eventual loss of cellular integrity.

The present thesis deals with the synthesis, characterisation and implementation of metal-ferrous or ferrous-ferric hydroxide hybrid nanomaterials for the study of electron transfer and electrocatalytic reduction of H₂O₂.The first chapter presents the synthesis and characterisation of ferrous and ferric ferrous hydroxides, carbonated and sulphated green rusts and chukanovite, as well as the corresponding nanohybrids with silver and gold nanoparticles. The second chapter is devoted to the interactions of ferrous or ferric ferrous hydroxide with chromate ion and metal ions (AgⅠ and AuⅢ) and the study of electron transfer. Kinetic studies of the redox interaction of these compounds with chromium (VI) were carried out. The general interaction model of Legrand et al, proposed for RVc, has been validated also for Chu and RVs in the present work. This model considers a decrease of the interaction kinetics by progressive formation of passivating CrIII monolayers. Comparison of the kinetic constants ki allows the compounds to be classified according to their reactivity, RVs ≈ RVc > Chu. The characteristic parameter n0, number of surface sites available for CrⅢ precipitation was determined for the different hydroxide samples and is maximal with Chu and RVs synthesised at 25°C. Subsequently, the reactivity of the Fe(II)-containing matrix towards metal ions was studied. We measured the reaction rates of FeII with AuIII for unmodified VCR, for VCR partially oxidised by air and for VCR passivated with Cr(III). The electron transfer kinetics remain very fast in the inorganic matrix and at the solid/solution interface, except when the passivation is 99% where a very strong slowing down of the interaction and a modification of the morphology of the gold string deposits are observed. In the last chapter, we detailed the development of a new electrochemical sensor based on nanohybrids, mainly Ag-exRVc but also Ag-exChu, Ag-exRVs or Au-exRVc, mixed with carbon ink and applied on a stainless steel disk, and we used them for the electrocatalytic reduction of H₂O₂. The electrochemical behaviour was studied by cyclic voltammetry and chronoamperometry and we showed that there are synergistic effects between the redox properties of the FeIII/FeII system of the inorganic matrix and the surface activity of the silver nanoparticles during the electro-catalysis of hydrogen peroxide reduction. Secondly, we showed that it is possible to combine these nanohybrids with the enzyme Glucose Oxidase in a glucose amperometric biosensor and exploit their electro-catalytic properties for H₂O₂ reduction. Using chronoamperometry and under optimised experimental conditions, the fabricated biosensor shows good catalytic performance for the determination of glucose by reduction of H2O2 formed during the enzymatic reaction, with satisfactory sensitivity and low detection limit., Le présent travail de thèse porte sur la synthèse, la caractérisation et la mise en œuvre de nanomatériaux hybrides métal-hydroxyde ferreux ou ferreux ferriques pour l'étude de transferts d'électrons et la réduction électrocatalytique de H₂O₂.Le premier chapitre présente la synthèse et la caractérisation des hydroxydes ferreux et ferreux ferriques, rouilles vertes carbonatée et sulfatée et chukanovite, ainsi que les nanohybrides correspondants avec des nanoparticules d'argent et d'or. Le deuxième chapitre est consacré aux interactions des hydroxyde ferreux ou ferreux ferriques vis-à-vis de l'ion chromate et des ions métalliques (AgⅠet AuⅢ) et à l'étude des transferts d'électrons. Des études cinétiques de l'interaction redox de ces composés avec le chrome (VI) ont été réalisées. Le modèle général d'interaction de Legrand et al, proposé pour la RVc, a été validé également pour la Chu et la RVs dans le présent travail. Ce modèle considère une diminution de la cinétique d'interaction par formation progressive de monocouches passivantes de CrIII. La comparaison des constantes cinétiques ki permet de classer les composés selon leur réactivité, RVs ≈ RVc > Chu. Le paramètre caractéristique n0, nombre de sites de surface disponibles pour la précipitation de CrⅢ a été déterminé pour les différents échantillons hydroxydes et est maximal avec la Chu et la RVs synthètisées à 25°C. Par la suite, la réactivité de la matrice contenant le Fe(II) vis-à-vis d'ions métalliques a été étudiée. Nous avons mesuré les vitesses de réaction du FeII avec AuIII pour la RVc non modifiée, pour la RVc partiellement oxydée par l'air et pour la RVc passivée avec du Cr(III). Les cinétiques de transfert d'électrons restent très rapides dans la matrice inorganique et à l'interface solide/solution, sauf lorsque la passivation est à 99% où un très fort ralentissement de l'interaction et une modification de la morphologie des dépôts d'or en chapelets sont constatés. Dans le dernier chapitre, nous avons détaillé l'élaboration d'un nouveau capteur électrochimique à base de nanohybrides, Ag-exRVc majoritairement mais aussi Ag-exChu, Ag-exRVs ou Au-exRVc, mélangés à de l'encre carbone et appliqués sur un disque d'inox, et nous les avons utilisés pour la réduction électrocatalytique de H₂O₂. Le comportement électrochimique a été étudié par voltammétrie cyclique et chronoampérométrie et nous avons montré qu'il existe des effets synergiques entre les propriétés redox du système FeIII/FeII de la matrice inorganique et l'activité de surface des nanoparticules d'argent lors de l'électro-catalyse de la réduction du peroxyde d'hydrogène. Ensuite, nous avons montré qu'il est possible d'associer ces nanohybrides avec l'enzyme Glucose Oxydase dans un biocapteur ampérométrique à glucose et d'y exploiter leurs propriétés électro-catalytiques pour la réduction de H₂O₂. En utilisant la chronoampérométrie et sous conditions expérimentales optimisées, le biocapteur fabriqué présente de bonnes performances catalytiques pour la détermination du glucose par réduction du H₂O₂ formé au cours de la réaction enzymatique, avec une sensibilité satisfaisante et une faible limite de détection.

International audience; The increasing population and industrial development are responsible for environmental pollution. Among toxic chemicals, polycyclic aromatic hydrocarbons (PAHs) are highly carcinogenic contaminants resulting from the incomplete combustion of organic materials. Two-dimensional materials, such as transition metal dichalcogenides (TMDCs), are ideal sensory scaffolds, combining high surface-to-volume ratio with physical and chemical properties that are strongly susceptible to environmental changes. TMDCs can be integrated in field-effect transistors (FETs), which can operate as high-performance chemical detectors of (non)covalent interaction with small molecules. Here, we have developed MoS2-based FETs as platforms for PAHs sensing, relying on the affinity of the planar polyaromatic molecules for the basal plane of MoS2 and the structural defects in its lattice. X-ray photoelectron spectroscopy analysis, photoluminescence measurements, and transfer characteristics showed a notable reduction in the defectiveness of MoS2 and a p-type doping upon exposure to PAHs solutions, with a magnitude determined by the correlation between the ionization energies (EI) of the PAH and that of MoS2. Naphthalene, endowed with the higher EI among the studied PAHs, exhibited the highest output. We observed a log–log correlation between MoS2 doping and naphthalene concentration in water in a wide range (10–9–10–6 M), as well as a reversible response to the analyte. Naphthalene concentrations as low as 0.128 ppb were detected, being below the limits imposed by health regulations for drinking water. Furthermore, our MoS2 devices can reversibly detect vapors of naphthalene with both an electrical and optical readout, confirming that our architecture could operate as a dual sensing platform.

Metal dusting is a kind of catastrophic carburization of iron or nickel-base alloys. This phenomenon occurs when the gas mixture is carbon-rich, at temperatures higher than 900°C. The aim of this work consists in forming a protective oxide scale against carburization on the surface of model alloys. In the present work, four model alloys (Fe26Cr, Fe26Cr2Si, Ni25Cr and Ni25CrSi) were pre-oxidized at 900 and 950 °C in a high oxygen containing gas (dry air) or in a low containing oxygen gas mixture (N2-5%H2). Thus, blank and pre-oxidized alloys were exposed to a highly carburizing environment (Ar-10%CH4), at 900 °C. The pre-oxidation study focuses on the oxide scale morphologies and diffusion mechanisms in the oxide scales. Carburization tests show that it is possible to influence the protectiveness of the oxide scales depending on the oxidizing gaseous environment, and temperature. Thereby, a chromia scale alone and/or a non-adherent scale is not an effective way to prevent carburization in highly carburizing environments. However, the presence of silicon in ferritic alloys is beneficial. Its presence in the ferritic matrix prevents chromium carbide formation inside the alloy grains. After oxidation, an amorphous silica scale also limits carbon ingress along the alloy grain boundaries. Silica is chemically more stable than chromia. Then, its presence appears to be essential to ensure a good protection. On the other hand, the non-continuous cristobalite scale formed on austenitic alloys does not appear to be protective enough., Le « metal dusting » est une carburation catastrophique des alliages à base de fer ou de nickel. Ce phénomène a lieu lorsque le mélange gazeux est sursaturé en carbone, à des températures supérieures à 900°C. L’objectif de ce travail consiste à former une couche protectrice d'oxyde sur la surface des alliages. Pour cela, quatre alliages chrominoformeurs modèles (Fe26Cr, Fe26Cr2Si, Ni25Cr et Ni25Cr2Si) sont pré-oxydés à 900 et 950°C dans un mélange gazeux à forte teneur en oxygène (air sec) ou à faible teneur en oxygène (N2-5%H2). Chaque alliage a ensuite été exposé à un environnement fortement carburant (Ar-10%CH4) à 900°C. La carburation des alliages bruts est comparée à celle des alliages recouverts d'une couche d'oxyde. L’étude de l'oxydation met l’accent sur l'aspect morphologique et les mécanismes de diffusion dans les couches d'oxyde formées. Le travail concernant la carburation montre qu’il est possible d’influencer le caractère protecteur des couches de pré-oxydation en fonction du choix de l'environnement gazeux et de la température. Ainsi, la constitution d’une couche de chromine seule et/ou d’une couche non adhérente ne sont pas des situations efficaces pour lutter contre la carburation dans des environnements très carburants. Par contre, la présence du silicium dans les alliages ferritiques est avantageuse à double titre. Sa présence dans la matrice ferritique permet d’éviter la formation des carbures de chrome à l'intérieur des grains de l’alliage. Au cours de la pré-oxydation, le silicium permet également d’obtenir une couche de silice amorphe qui limite la pénétration du carbone dans les joints de grains de l'alliage. Cette couche de silice a l’avantage d’être plus stable chimiquement que la couche de chromine et sa présence apparaît indispensable afin d'assurer une bonne protection. En revanche, la couche non continue de cristobalite obtenue sur les alliages austénitiques n'apparaît pas comme étant aussi protectrice que la silice amorphe.

International audience; We have investigated the early stages of formation of iron oxide nanoparticles from iron stearate precursors in the presence of sodium stearate in an organic solvent by in situ liquid phase transmission electron microscopy (IL-TEM). Before nucleation, we have evidenced the spontaneous formation of vesicular assemblies made of iron polycation-based precursors sandwiched between stearate layers. Nucleation of iron oxide nanoparticles occurs within the walls of the vesicles, which subsequently collapse upon consumption of the iron precursors and growth of the nanoparticles. We then evidenced that fine control of the electron dose, and therefore of the local concentration of reactive iron species in the vicinity of the nuclei, enables controlling crystal growth and selecting the morphology of the resulting iron oxide nanoparticles. Such direct observation of the nucleation process templated by vesicular assemblies in a hydrophobic organic solvent sheds new light on the formation process of metal oxide nanoparticles and therefore opens ways for the synthesis of inorganic colloidal systems with tunable shape and size.