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Antimony Trioxide Extraction from E-Waste Brominated Flame-Retardant Laden Plastics by Simultaneous Liquid–Liquid Extraction and Leaching
No full textInternational audienceA novel method for extracting antimony from electronic waste plastics has been investigated in this work. Antimony trioxide is initially incorporated into these plastics in synergy with brominated molecules hence their common name "brominated plastics". This combination offers excellent flameretardant properties. The mechanical recycling of brominated plastics is prohibited due to the hazardous nature of the molecules that are generated during the process. Therefore, this article explores the use of a plastic dissolution method combined with liquid-liquid interfacial leaching to remove antimony trioxide while recovering a plastic cleansed of this problematic additive. The primary investigative focus pertained to the refinement of the aqueous extractant solution, while the secondary focus centred on the selection of the dissolution solvent. The process demonstrates high efficiency in antimony extraction, achieving up to 98 mass% recovery, with minimal impact on the structural integrity of the ABS (Acrylonitrile Butadiene Styrene) plastic. By insolubilizing the plastic to recover it, it is also feasible to recover up to 98 mass% of the brominated molecules, thereby ensuring compliance with legal thresholds for the reuse of plastics. This methodology not only</div
Comparative analysis of electric potential in p-GaN/InGaN/n-GaN nanowire LEDs
No full textInternational audienceRecent advances in the development of deep ultraviolet, light emitting diodes (LEDs) have been reported for nanowire (NW) device geometries composed of nitride semiconductors. Typically, these involve arrays of NWs where the level of variation in the electrical and optical properties of individual NW LEDs is unknown. In this work, the electric potential distributions in axial p-GaN/InGaN/n-GaN NW LEDs grown by plasma-assisted molecular beam epitaxy are investigated using electron holography (EH). Two kinds of NWs are observed to grow simultaneously on the same substrate. One type exhibits a long, thin morphology and a varying diameter, while the other has a short, wide morphology with a uniform diameter. Although the bottom p-GaN and InGaN regions have similar lengths in both types, the top n-GaN region are five times longer in the first type. Photoluminescence spectra from arrays, show an InGaN emission peak ranging from 2.55 eV to 2.65 eV, which indicates an average In composition of 20 ± 3 percent. This is consistent with energy dispersive x-ray maps from individual NWs of both types, which reveal a core/shell InGaN/GaN structure with similar composition. However, the EH potential maps reveal a built-in junction voltage of approximately 3 V in the long, thin NWs, while the short NWs exhibit a drastic reduction, with a junction voltage of only 0.6 V. The difference is primarily attributed to the length of the short wire n-doped segment being too short to reach the flat potential of a complete p–n junction
A Microfluidic Platform for Actin‐Based Membrane Remodeling Reveals the Stabilizing Role of Branched Actin Networks on Lipid Microdomains
No full textInternational audienceCell shape changes, essential for processes such as motility or division, are controlled by the actomyosin cortex that actively remodels biological membranes. Their mechanisms can be deciphered in vitro using biomimetic reconstituted systems, such as giant unilamellar vesicles (GUVs) with controlled lipid composition coupled to reconstituted actin networks. These assays allow mimicking cell shape changes in controlled biochemical and biophysical environments. However, studying the dynamics of these shape changes on statistically significant populations of GUVs with the possibility to sequentially modify the protein composition of the assay is a major experimental challenge. To address these issues, a microfluidic approach is used to immobilize several dozens of isolated GUVs and monitor membrane and actin network evolution. The loading of the chamber with GUVs and actin is first characterized. Then, the actin‐induced remodeling of populations of homogeneous and phase‐separated GUVs is monitored and shows that actin networks prevent the coalescence of lipid microdomains and that, in return, the number of domains affects the actin network structure. This microfluidic‐based experimental strategy, thus, allows for studying actin‐induced membrane deformation in vitro and can be adapted to other studies on membrane remodeling processes
Supramolecular “sergeants”: in situ and multi-level induction of chirality in helical assemblies of triarylamine trisamide monomers
No full textInternational audienceThe induction and transmission of chirality across multiple length scales is fundamental to many (bio) chemical processes. For the majority of macromolecular and supramolecular structures adopting a helical configuration, this is harnessed by means of a monomer embedding a stereogenic element, also called a “sergeant” because of its ability to transfer its chirality preference to achiral monomers. Herein, we devise a triarylamine trisamide (TATA) monomer embedding a (thio)urea unit able to interactwith a chiral phosphate anion through hydrogen bonding. Thanks to the orthogonal nature of the amide and (thio)urea functions, the anion specifically binds to the (thio)urea unit, thus yielding a supramolecular monomer acting as a “sergeant” i.e. allowing efficient chirality induction in amide-bonded TATA helical copolymers composed of various types of achiral TATA monomers. Unlike covalent “sergeants”, chirality can be induced in situ by binding of the chiral anion to pre-formed coassemblies. In addition, the catalytic performance of TATA coassemblies embedding intrinsically achiral phosphine-functionalized TATA monomers has been evaluated: higher enantioselectivities are reached with the supramolecular versus covalent “sergeant”. Our work may facilitate the design and development of supramolecular“sergeants” as a modular approach to induce chirality in supramolecular helical copolymers and catalysts
Processing and shaping of large diamonds using a laser microjet technology
No full textInternational audienceDiamond has excellent thermal conductivity, unique electrical properties and hardness that enable high-end technologies and make it a strategic material [1]. In recent years, significant improvements have been achieved regarding lab-grown diamond quality and purity both for power electronics and quantum technologies, two applications in which diamond is an outstanding material platform. In particular, diamond substrates larger than 1 cm² are now commercially available although they remain relatively scarce. Prospects in reproducibly achieving “wafer sizes” of several inches are already on the right track, thanks to advances in mosaic and heteroepitaxial growth [2]. These advancements have opened up new possibilities for the application of diamond in various high-tech fields, at an industrial scale. However, as a hard material, these improvements in diamond dimensions come with a drawback: shaping, slicing and polishing large diamond films become a significant challenge. The precision required for cutting and shaping diamonds into specific forms for various applications is also ever more complex and technically demanding to facilitate integration of the material into specific devices. Traditional methods based on standard laser technologies often fall short in terms of accuracy and can lead to material waste or damage. In this presentation, we will focus on this particular topic, describing the advantages of using a laser microjet technology dedicated to diamond processing [3]. With this approach, the laser is guided through a narrow water jet allowing an optimal focus of the beam and minimal material loss throughout the processing. We will demonstrate how optimal processing conditions can be tuned for slicing large diamonds (> 1 inch in diameter) and recycling substrates used for homoepitaxial growth. [1] Bucciolini, M., C. De Angelis, and C. Talamonti, 8.15 - Diamond Detectors for Dosimetry, in Comprehensive Biomedical Physics, A. Brahme, Editor 2014, Elsevier: Oxford. p. 229-248.[2] J.-C. Arnault, S. Saada, V. Ralchenko, Chemical Vapor Deposition Single-Crystal Diamond: A Review, Physica Status Solidi (RRL) – Rapid Research Letters 16 (2022) 2100354. [3] https://www.synova.ch/technology/synova-laser-microjet.htm
Impact of X‐ray Irradiation on the Chemistry and Structure of Biogenic Hydroxyapatite: The Case of Human Enamel
No full textInternational audienceThe influence of X-ray irradiation on dental tissues has been widely studied in the context of radiotherapy for the treatment of head and neck cancer. An observation common to almost all previous reports is the decrease of enamel hardness after irradiation. However, the origin of this loss of mechanical resistance remains a matter of debate. Here, we have conducted a chemical and structural study of the effect of a single 70 Gy dose on human teeth mineralized tissues. Vickers hardness of both enamel and dentin was decreased after irradiation. Microcomputed tomography showed that only the hydroxyapatite density of enamel was modified. Scanning electron microscopy, X-ray diffraction and Raman micro-spectroscopy indicated that the chemistry and crystallinity of the inorganic phase of enamel, and its organization at the micron scale, were not modified. However, Raman spectra highlighted a disorientation of hydroxyapatite nanocrystallites over the whole enamel thickness. The decrease of enamel hardness was correlated with the decrease of mineral density by assuming the presence of an additional irradiation-induced porosity. Our data suggest that X-ray irradiation can create local defects in the enamel structure, decreasing its mechanical stability. These results shed new light on the interactions between X-rays and hydroxyapatite-based materials
Building a community lightsource meta-infrastructure to accelerate battery innovation in Europe
No full textInternational audienceBreakthroughs in battery research are imperative to provide society with batteries that are safe and sustainable, have a high energy density, and have a long cycle life at low cost. Recent advances in research methodologies, the emergence of new market opportunities, and strategic funding schemes have allowed not only large, but also small companies, universities, and public research organizations to play an increasingly significant role in the advancement of battery technology. Challenges in battery technology development are multifaceted; therefore, a collaborative approach is crucial to bring together various stakeholders and ensure access to the full range of technical and scientific expertise. To grasp the core properties of electrode materials, electrolytes, and interfaces and to identify the mechanisms of battery degradation and failure, a multidisciplinary analytical approach is crucial. This strategy relies on the unique and complementary potential of advanced characterization techniques available at synchrotron and x-ray free electron laser facilities. Science-to-industry interactions are expected to increase the development of new standardized setups to approach realistic operando conditions. Therefore, rapid access to instruments, including high-throughput ex-situ , in-situ and operando capabilities, is key to accelerating the development of safe and sustainable batteries. The purpose of this paper is to discuss how the characterization needs of the battery community can be met by establishing a collaboration network based on a meta-infrastructure model, where the emphasis will be on collaboration and the sharing of experience and data. The proposed methodology considers the urgency in the battery community and the necessary technical developments to reach the scope of collaboration and focuses in particular on the needs for standardization, big data challenges, and open data approaches
Coupling differential voltage analysis and distribution of relaxation times I: Evaluating the impact of NMC811 coating in the degradation of NMC811/Gr cells
No full textInternational audienceThis paper focuses on the coupling of the Differential Voltage Analysis (dV/dQ vs Q) and the Distribution of Relaxation Times (DRT), whose benefits to electrodes development are illustrated by the tracking of degradation effects in the cycling aging of NMC811/Gr coin cells, with and without an NMC electrode coating. The former technique allows monitoring of individual electrode loss of active material (LAM), chemistry change and state of charge (SOC) alignment of the electrodes, whose variation is related mainly to loss of Li inventory (LLI). DRT is a time domain representation of the impedance that offers a high resolution of the resistance processes, complementing the DVA analysis by bringing kinetics degradation of the cells and by identifying in which electrode the main resistance processes are originated. The protocol inserting those techniques in an aging regime is a non-invasive approach, and it indicated the consumption of Li+ ions as the main reason for capacity decay in both cells, with reduced or minimal NMC LAM and chemistry change when coating is applied. From the perspective of power decay, the coating decelerated the impedance rise (IR), mostly related to resistance processes in the positive electrode
Pyridylidene transition metal complexes – An underexplored class of organometallic carbenes
No full textInternational audiencePyridylidene compounds, carbene isomers of related pyridines, remain a fascinating class of intermediates in organic synthesis. Although of high interest as ligands in organometallic and coordination chemistry, this aspect is by far underexplored because of obvious lack of general and efficient synthetic methodologies. This review summarizes the relatively few reported examples of organometallic compounds with pyridylidene ligands. Several important reported examples recently open the way to a promising development of this class of carbenes in organometallic catalysis, biology or materials sciences
Large-Scale Characterization of Chemical Bonding and Topology in the Materials Project Database
No full textInternational audienceTopology is key to the determination of many physical and chemical properties of materials, such as electrical, optical, and magnetic properties, as well as thermal and mechanical behavior. However, despite the growing number of databases of crystalline materials available, there has been very little systematic effort to date to analyze their topology. In this work, we have leveraged recent algorithmic advances in the analysis of chemical bonding and topology determination in order to perform high-throughput analysis of topology of materials on a large-scale database of existing and hypothetical materials, the Materials Project data set of more than 170,000 structures. Beyond the statistical analysis of the most frequent topologies and coordination environments, the publication of these topological data will allow researchers to search for materials by topology and chemical environment, paving the way to enhanced performance in materials screening for applications. We demonstrated two examples of the usefulness of topological considerations in such computational screening