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Atmospheric-Pressure Operation of All-Solid-State Batteries Enabled by Halide Solid Electrolyte
No full textInternational audienceAll-solid-state batteries aim to provide increased safety and higher energy density for next-generation energy storage. However, challenges remain due to volume changes and inadequate contact between the cathode active material and solid electrolyte particles, leading to poor cyclability. This study investigates the use of the halide-based Li3YBr2Cl4 solid electrolyte to address these issues. Through experimental evaluations with the LiNi0.6Mn0.2Co0.2O2 cathode material, we demonstrate reliable operation down to 0.1 MPa against a LiIn alloy and 0.2 MPa against a Li metal anode, with limited capacity loss. Furthermore, we observe that pressures below 5 MPa do not hinder the rate capabilities, retaining 70% of the C/20 capacity even under 1C discharge rate. These findings underscore the potential of halide-based ASSBs for practical applications and Li metal integration, providing insights for developing reliable low-pressure all-solid-state battery systems
Voltammetric techniques for low-cost on-site routine analysis of thymol in the medicinal plant Ocimum gratissimum
No full textInternational audienceThe composition of essential oils varies according to culture conditions and climate, which induces a need for simple and inexpensive characterization methods close to the place of extraction. This appears particularly important for developing countries. Herein, we develop an analytical strategy to determine the thymol content in Ocimum Gratissimum, a medicinal plant from Benin. The protocol is based on electrochemical techniques (cyclic and square wave voltammetry) implemented with a low cost potentiostat. Thymol is a phenol derivative and was directly oxidized at the electrode surface. We had to resort to submillimolar concentrations (25–300 μM) in order to minimize production of phenol oligomers that passivate the electrode. We worked first on two essential oils and realized that in one of them the thymol concentration was below our detection method. These results were confirmed by gas chromatography – mass spectrometry. Furthermore, we optimized the detection protocol to analyze an infusion made directly from the leaves of the plant. Finally, we studied whether the cost of the electrochemical cell may also be minimized by using pencil lead as working and counter electrodes
Unveiling the Full Dynamical and Reactivity Profiles of Acetylcholinesterase: A Comprehensive All-Atom Investigation
No full textInternational audienceAcetylcholinesterase is one of the most significant known serine hydrolases, governing the mammalian nervous system. Its high rate speed, operating at the diffusion limit, combined with its buried active site feature, has made it a subject of extensive research over the last decades. Despite several studies focused on atomistic details of its different steps, a comprehensive theoretical investigation of the entire catalytic cycle has not yet been reported. In this work, we present an intuitive workflow aiming at describing the full dynamical and reactive profiles of AChE by coupling extensive Steered Molecular Dynamics (SMD) simulations for ligand diffusion and hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) computations to decipher the complete reactivity of the substrate within the enzyme. This comprehensive approach provides a broader view of the interconnections between each step that would not be readily accessible if studied independently. Our simulations reveal that although individual steps do not indicate any strong limiting step, a solvent water molecule reorganization between the acylation and deacylation processes through the reactivity results in an energy cost of 20 kcal/mol. The observed barrier surpasses all others and discloses insights on a strong polarization effect acting on water molecules near the active site. An AMOEBA polarizable Molecular Dynamics simulation tends to confirm this assumption by capturing a substantial dipole moment (3.10 D) on the water molecule closest to the reaction site. These results shed light on the crucial correlation between this high--energy water reorganization and the polarization of confined water molecules. Consequently, carefully considering and modeling buried (polarizable) water molecules is of paramount importance when modeling full enzymatic activity. Therefore, this work will also provide valuable insights for future research on related enzymes with buried active sites
Interface Characterization by Nanoindentation and EBSD of Cu/Cu and Al/Cu Joints Produced by Magnetic Pulse Welding (MPW)
No full textInternational audienceMagnetic Pulse Welding (MPW) is a high-velocity impact welding technique that allows the joining of dissimilar materials such as aluminium and copper. Welding should be produced under the appropriate conditions: impact velocity (200-500 m.s-1) and collision angle (10-30°). The formation mechanisms leading to the welding creation are not very clear. This work investigates the microstructure and hardness at the interface to understand these mechanisms. Al/Cu and Cu/Cu samples were formed with identical process parameters. They were first compared to the literature using Vickers microhardness. Obtained results are standard and correspond to previous studies. In a second step, a detailed characterization of the interface using nanoindentation and electron backscattered diffraction (EBSD) methods is done. Different behaviors were found at the interface between Al/Cu and Cu/Cu. Al/Cu exhibited a thin layer of intermetallic compounds (IMC), increasing the hardness at the interface. This layer was composed of Al2Cu and Al4Cu9 compounds, as demonstrated by Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD). Cu/Cu presented a dissimilar behavior at the interface. The flyer sheet shows an increase in hardness due to grains deformation and distortion. While, the base sheet manifested a decrease in hardness caused by dynamic recovery or recrystallization at the interface. In both cases, the samples were deformed and hardened due to the plastic deformation induced during impact. These results are complementary to previous studies. They provide new insights that could be used to improve our understanding of the mechanisms behind such high-velocity impact welding
Recent advances in Fe-based bioresorbable stents: Materials design and biosafety
No full textInternational audienceFe-based materials have received more and more interests in recent years as candidates to fabricate bioresorbable stents due to their appropriate mechanical properties and biocompatibility. However, the low degradation rate of Fe is a serious limitation for such application. To overcome this critical issue, many efforts have been devoted to accelerate the corrosion rate of Fe-based stents, through the structural and surface modification of Fe matrix. As stents are implantable devices, the released corrosion products (Fe2+ ions) in vessels may alter the metabolism, by generating reactive oxygen species (ROS), which might in turn impact the biosafety of Fe-based stents. These considerations emphasize the importance of combining knowledge in both materials and biological science for the development of efficient and safe Fe-based stents, although there are still only limited numbers of reviews regarding this interdisciplinary field. This review aims to provide a concise overview of the main strategies developed so far to design Fe-based stents with accelerated degradation, highlighting the fundamental mechanisms of corrosion and the methods to study them as well as the reported approaches to accelerate the corrosion rates. These approaches will be divided into four main sections, focusing on (i) increased active surface areas, (ii) tailored microstructures, (iii) creation of galvanic reactions (by alloying, ion implantation or surface coating of noble metals) and (iv) decreased local pH induced by degradable surface organic layers. Recent advances in the evaluation of the in vitro biocompatibility of the final materials and ongoing in vivo tests are also provided
La mutation humaine VGLUT3-pT8I induit une signalisation dopaminergique striatale inégale et une consommation inadaptée d'aliments ou de drogues chez les souris mâles.
No full textInternational audienceAbstract Cholinergic striatal interneurons (ChIs) express the vesicular glutamate transporter 3 (VGLUT3) which allows them to regulate the striatal network with glutamate and acetylcholine (ACh). In addition, VGLUT3-dependent glutamate increases ACh vesicular stores through vesicular synergy. A missense polymorphism, VGLUT3-p.T8I, was identified in patients with substance use disorders (SUDs) and eating disorders (EDs). A mouse line was generated to understand the neurochemical and behavioral impact of the p.T8I variant. In VGLUT3 T8I/T8I male mice, glutamate signaling was unchanged but vesicular synergy and ACh release were blunted. Mutant male mice exhibited a reduced DA release in the dorsomedial striatum but not in the dorsolateral striatum, facilitating habit formation and exacerbating maladaptive use of drug or food. Increasing ACh tone with donepezil reversed the self-starvation phenotype observed in VGLUT3 T8I/T8I male mice. Our study suggests that unbalanced dopaminergic transmission in the dorsal striatum could be a common mechanism between SUDs and EDs.Les interneurones cholinergiques striataux (ChI) expriment le transporteur vésiculaire de glutamate 3 (VGLUT3), ce qui leur permet de réguler le réseau striatal par le glutamate et l'acétylcholine (ACh). De plus, le glutamate, dépendant de VGLUT3, augmente les réserves vésiculaires d'ACh par synergie vésiculaire. Un polymorphisme faux-sens, VGLUT3-p.T8I, a été identifié chez des patients présentant des troubles liés à l'usage de substances (TUS) et des troubles du comportement alimentaire (TCA). Une lignée de souris a été générée afin d'étudier l'impact neurochimique et comportemental de la variante p.T8I. Chez les souris mâles VGLUT3 T8I/T8I, la signalisation glutamatergique est inchangée, mais la synergie vésiculaire et la libération d'ACh sont atténuées. Ces souris mâles mutantes présentent une libération de dopamine réduite dans le striatum dorsomédial, mais pas dans le striatum dorsolatéral, ce qui favorise la formation d'habitudes et exacerbe les comportements alimentaires ou l'usage inapproprié de drogues. L'augmentation du tonus cholinergique induite par le donépézil a inversé le phénotype d'auto-privation observé chez les souris mâles VGLUT3 T8I/T8I. Notre étude suggère qu'un déséquilibre de la transmission dopaminergique dans le striatum dorsal pourrait constituer un mécanisme commun aux troubles liés à l'usage de substances et aux troubles du comportement alimentaire
N-Heterocyclic Carbene Boranes: Dual Reagents for the Synthesis of Gold Nanoparticles
No full textInternational audienceGold nanoparticles (AuNPs) is an interesting class of plasmonic nanomaterials owing to their distinctive properties, making them valuable in several applications such as nanocatalysis, nanomedicine, and electronics. Stabilization of these nanomaterials in colloidal suspension to ensure their functionality in the abovementioned applications is a crucial challenge. Due to their formally divalent carbon atom and soft Lewis base character, N-Heterocyclic Carbenes (NHCs) have gained interest in the past decade as strong-binding surface ligands for gold nanoparticles (AuNPs) that can outperform thiols. Typically, in “bottom-up” approach, NHC-stabilized AuNPs (NHC-AuNPs) are synthesized by the reduction of either well-defined Au(I)-NHC complexes or imidazolium haloaurate salts. This method generally produces small NHC-AuNPs (~1-6 nm) as a result of using an excessive amount of reducing agent and the constrained 1:1 ratio of gold-to-ligands in the initial precursor, which makes the nanoparticles size difficult to control. Here we describe a novel “bottom-up” synthesis towards NHC-AuNPs by using NHC-BH3 adduct as a dual reagent, where NHC-BH3 not only acts as a reductant but also as a source of NHCs for nanoparticles stabilization. A simple mixing of NHC-BH3 and readily available Au(I) leads to the formation of monodisperse NHC-AuNPs in quantitative yield validated by UV-Vis spectroscopy. X-ray photoelectron spectroscopy (XPS) was used to characterize the nature of the nanoparticles and to confirm the presence of NHCs as capping ligands on the AuNP surface. In addition, this approach allows the control over the nanoparticle size over the range of 4.9 ± 0.9 to 10.0 ± 2.7 nm by changing the NHC-BH3/Au(I) ratio, as demonstrated by TEM studies. Mechanistic studies including NMR spectroscopy and mass spectrometry demonstrate that the reduction of gold(I) generates NHC-BH2Cl as a by-product. Moreover, for the first time, a precise and controlled seed-mediated growth of gold nanoparticles from 4.8 ± 0.8 nm to 7.7 ± 1.0 nm was achieved using NHC-BH3. This strategy will likely open the possibility of elaboration of more complex nanostructure or bimetallic nanoparticles. This work showcases a practical synthesis towards NHC-AuNPs with tuned size which does not require pre-isolation of NHC-gold complex or imidazolium-gold salt
Iron-catalyzed synthesis of substituted 3-arylquinolin-2(1 H )-ones via an intramolecular dehydrogenative coupling of amido-alcohols
No full textInternational audienceAn iron-catalyzed intramolecular dehydrogenative coupling of amido-alcohols, opening a straightforward access to 3- or 3,4-substituted quinolinones, is described in this report
Spin-bearing molecules as optically addressable platforms for quantum technologies
No full textInternational audienceEfforts to harness quantum hardware relying on quantum mechanical principles have been steadily progressing. The search for novel material platforms that could spur the progress by providing new functionalities for solving the outstanding technological problems is however still active. Any physical property presenting two distinct energy states that can be found in a long-lived superposition state can serve as a quantum bit (qubit), the basic information processing unit in quantum technologies. Molecular systems that can feature electron and/or nuclear spin states together with optical transitions are one of the material platforms that can serve as optically addressable qubits. The attractiveness of molecular systems for quantum technologies relies on the fact that molecular structures of atomically defined nature can be obtained in endless diversity of chemical compositions. Crucially, by harnessing the molecular design protocols, the optical and spin (electronic and nuclear) properties of molecules can be tailored, aiding the design of optically addressable spin qubits and quantum sensors. In this contribution, we present a concise and collective discussion of optically addressable spin-bearing molecules – namely, organic molecules, transition metal (TM) and rare-earth ion (REI) complexes – and highlight recent results such as chemical tuning of optical and electron spin quantum coherence, optical spin initialization and readout, intramolecular quantum teleportation, optical coherent storage, and photonic-enhanced optical addressing. We envision that optically addressable spin-carrying molecules could become a scalable building block of quantum hardware for applications in the fields of quantum sensing, quantum communication and quantum computing
Cyclodextrin‐encapsulated NHCs: increased selectivity and reactivity of CO2 in amine formylation
No full textInternational audienceHerein, we describe the confinement of a N‐Heterocyclic Carbene (NHC) organocatalyst in the cavity of cyclodextrins (CDs). These confined organocatalysts allow the formylation of amines through CO2 hydrosilylation. The presence of the cavity of the CDs leads to substrate‐selectivity between amines in competition reactions. The use of the smallest α‐CD induces the best selectivities but also to increased reactivity compared to the bigger β‐CD. A careful study conducted by NMR and DFT revealed that in α‐CD, the complexed CO2 interacts with the cavity through hydrogen bonds. These H‐bonds destabilize the NHC–CO2 adduct and are accountable for the higher reactivity observed using α‐CD