HAL-CEA
Not a member yet
145450 research outputs found
Sort by
An optimized electrically conductive Si-Fe matrix to boost the performance of Si electrodes in Li-ion Batteries
No full textInternational audienceThe development of Si-based anodes has opened the venue to increase the energy density in lithium-ion batteries (LIBs). Nonetheless, the use of Si-based electrodes usually leads to a gradual loss in the cell’s electrochemical performance due to the significant volume expansion of silicon in electrode reactions. Combining silicon, a poor electronic conductor, with an electronically conductive Li-inactive phase, is a promising strategy to alleviate the volume expansion of silicon during lithiation and delithiation while providing a robust electronic network. Si-Fe alloys are prospective candidates [1, 2, 3] which could be used to maintain the electronic network in the silicon electrodes. In this study, different Si-Fe alloys are synthesized using ball-milling (BM) and arc melting (AM) techniques, leading to highly different chemical compositions and powder morphologies to better understand the role of iron silicide inactive phases in electrochemical reactions and optimize their performance. The use of AM results in the formation of Si and α-Fe2Si5 conducting matrix in a desired ratio, as expected from the Si-Fe binary phase diagram, while BM generates a mixture of phases, including undesirable products. Thanks to the presence of the inactive iron silicide phase (α-Fe2Si5), the electrical conductivity of the Si/α-Fe2Si5 composite can be increased up to 103 S.m-1, five orders of magnitude compared to pristine Si. The electrochemical testing results show that the performance of such a composite is strongly influenced by the balance between Si and inactive iron silicide phase, as well as their interparticle contact. Dilatometry tests in full cell configuration also demonstrate the advantage of using α-Fe2Si5 as a matrix to buffer Si volume change, prevent the loss of active material, and maintain a reversible swelling of 24% throughout cycling up to the 45th cycle. After optimization of electrode and electrolyte formulations, such composites could significantly outperform current Si/C electrodes in terms of volumetric capacity, rate capability and long-term cycling
Oxide glasses materials: potential candidates as positive electrodes active materials for Li-ion and Na-ion batteries
No full textInternational audienceDevelopment of new positive electrode (or cathode) active materials is important to improve Li-ion and Na-ionbatteries performances. Commercial materials are crystalline (LFP, NMC, …), but some studies reach interestingperformances developing Vanadium-containing glass cathodes [1], up to 1000 Wh/kg at the material level after 10cycles [2]. Glass asset is its disordered network which could theoretically incorporate high amount of transition metalsproviding high specific discharge capacities. It is also structural change tolerant, making alcalin insertion/deinsertionpossible during battery discharge/charge.Nevertheless, Vanadium is a toxic critical element, and the literature is scarce on Vanadium-free glass cathodes. Here,we explore new Vanadium-free phosphate based glass compositions as cathode active materials. The glasses weresynthetized using the melt-quenching technique, and characterized by X-ray diffraction (XRD), differential thermalanalysis-thermogravimetric analysis (DTA-TGA), scanning electron microscopy (SEM), energy-dispersive X-rayspectroscopy (EDX), and X-ray fluorescence (XRF) to determine their properties. Electrochemical ImpedanceSpectroscopy and Chronoamperometry were also performed on bulk glass to assess electrical and ionic conductivitiescontributions.Glass powders were then integrated in composite electrodes and assembled into coin cell in both Li-ion and Na-ionconfigurations. The electrochemical performances were evaluated through galvanostatic cycling using ARBIN benchat a low rate of C/50.Post-mortem analyses (Raman spectroscopy, XRD) were also conducted to investigate glass structure during cycling,as alkaline incorporation inside the positive electrode is frequently associated with phases formation or structuralchanges.As a whole, these characterizations will elucidate the mechanisms driving electrochemical performance. Results willbe added to a database to correlate glass composition with electrochemical performance, identify key parameters, andpredict optimized compositions. The aim is to achieve 1000 Wh/kg energy density with stable cycle life.References:[1] Wang et al., Journal of Non-Crystalline Solids, 619 (2023).[2] Afyon et al., Scientific Reports, 4:7113 (2014)
PET Imaging of PD-L1 Occupancy for Preclinical Assessment of the Efficacy of Combined Anti–PD-L1 Immunotherapy and Targeted Therapy
No full textInternational audienceThe development of resistance significantly hampers the efficacy of immunotherapies in cancer treatment. The combination of JQ1, a BRD4 protein inhibitor, and anti–programmed death ligand 1 (PD-L1) immunotherapies has a synergic therapeutic potential to treat solid tumors. This study aimed to evaluate the potential of immuno-PET imaging for measuring pharmacodynamic biomarkers in response to this combination therapy targeting PD-L1. Methods: We synthesized different radioligands derived from the anti–PD-L1 C4 antibody and a minibody targeting murine CD8α for immuno-PET imaging. We conducted experiments on human non–small cell lung cancer and mouse colorectal carcinoma animal models to assess the efficacy of JQ1 and avelumab treatment on PD-L1 expression and immune cell infiltration by immuno-PET imaging. Taking advantage of the unique properties of the C4-derived minibody, we measured PD-L1 occupancy in tumors after treatment. Results: JQ1 efficiently reduced PD-L1 extracellular expression across all tested cell lines in vitro and in vivo. Avelumab and JQ1 treatments alone or in combination led to significant tumor growth reduction in the immunocompetent murine colorectal carcinoma model, reducing mean tumor growth from 725% in the control group to 125% in the combination group. Treatments also significantly increased the survival of mice by 4–12 d compared with the control group. Although imaging CD8-positive T-cell infiltration did not predict tumoral response, imaging the unoccupied fraction of PD-L1 after treatment was predictive of tumor growth reduction and survival. Conclusion: Immuno-PET imaging with noncompetitive radioligands throughout the treatment course could improve the efficiency and support rationalization of the dosing regimen of immunotherapies
A low background setup for low energy X-ray detection in the context of the BabyIAXO/IAXO axion searches
No full textInternational audienceThe BabyIAXO (under construction) and the subsequent IAXO axion helioscopes shall convert hypothetical solar axions in a magnetic field to low energy (0.5 - 10 keV) X-rays, that may be detected within focal spots of about 6 mm diameter each. Since the expected event rate is very low, the X-ray detectors must have a background level below ~ 10-7 counts/keV/cm2/s, while the experimental setup, hosted at DESY, is situated above ground. The base line X-ray detectors are microbulk Micromegas gaseous detectors. However, since these detectors have a rather high energy threshold (~ 2 keV) and modest energy resolution, an R&D project addresses the comparison of the performance of several types of cryogenic detectors in terms of energy threshold, energy resolution and reachable background level with the MicroMegas detectors. In BabyIAXO (2 magnet bores) and in particular in the full IAXO setup that will comprise 8 magnet bores, the different focal planes can be equipped with different detector types offering different energy resolutions, energy thresholds and background levels.We will present a low background setup specifically developed to establish the background level that can be achieved above ground with X-ray detectors based on magnetic microcalorimeters (MMCs). It combines an external lead shield around a dilution refrigerator, an internal shield of low-activity lead and copper, and a cryogenic muon veto composed of germanium wafers also read out by MMCs. First results of test measurements with this setup will be shown
A review of biomass thermochemical gasification: Toward solar hybridized processes for continuous and controllable fuel production
No full textInternational audienceGasification of carbonaceous feedstocks into value-added syngas is a mature chemical process, developed at industrial scale for the production of chemicals and liquid fuels. Biomass gasification could open the path toward renewable fuel production, waste valorization, and carbon capture, but a fraction of the initial feedstock is burnt for process heat. Hence, allothermal solar heating is an attractive option for a clean and efficient production of syngas, enabling solar energy storage under a chemical form. Solar gasification potentially converts the whole feedstock mass while the produced syngas is not contaminated by combustion by-products and the high temperatures help to ensure high syngas yields with minimized char and tars production. Such results were however obtained under favorable solar power input conditions. In practice, the solar power fluctuations and intermittency must be managed carefully, with a control of the reactor inputs round the clock for stable syngas production. This review aims to provide a state-of-the-art on the variety of scientific topics involved in developing a stable and controllable solar gasification process, and it further addresses the challenges of hybridized solar-autothermal processes. Conventional gasification is first tackled, unraveling the historical background and current applications of the process. Associated chemical mechanisms are described, with some modeling considerations. Concentrated solar power technologies are then described, with a focus on thermochemical applications and existing solar gasification technologies. Finally, the methods to smoothen the effects of fluctuating solar power availability on solar syngas production are assessed, including thermal heat storage and solarautothermal hybridization for continuous day-night operation. The implementation of dynamic control methods is addressed, to assess the practical application of control strategies, paving the way toward continuous solar fuels production.</div
Sources of uncertainty in the SPITFIRE global fire model: development of LPJmL-SPITFIRE1.9 and directions for future improvements
No full textInternational audienceSince its development in 2010, the SPITFIRE global fire model has had a substantial impact on the field of fire modelling using dynamic global vegetation models. It includes process-based representations of fire dynamics, including ignitions, fire spread, and fire effects, resulting in a holistic representation of fire on a global scale. Previously, work had been undertaken to understand the strengths and weaknesses of SPITFIRE and similar models by comparing their outputs against remotely sensed data. We seek to augment this work with new validation methods and extend it by completing a thorough review of the theory underlying the SPITFIRE model to better identify and understand sources of modelling uncertainty. We find several points of improvement in the model, the most impactful being an incorrect implementation of the Rothermel fire spread model that results in large positive biases in fire rate of spread and a live grass moisture parametrization that results in unrealistically dry grasses. The combination of these issues leads to excessively large and intense fires, particularly on the dry modelled grasslands. Because of the tall flames present in these intense fires, which can cause substantial damage to tree crowns, these issues bias SPITFIRE toward high tree mortality. We resolve these issues by correcting the implementation of the Rothermel model and implementing a new live grass mois-ture parametrization, in addition to several other improvements, including a multi-day fire spread algorithm, and evaluate these changes in the European domain. Our model developments allow SPITFIRE to incorporate more realistic live grass moisture content and result in more accurate burnt area on grasslands and reduced tree mortality. This work provides a crucial improvement to the theoretical basis of the SPITFIRE model and a foundation upon which future model improvements may be built. In addition, this work further supports these model developments by highlighting areas in the model where high amounts of uncertainty remain, based on new analysis and existing knowledge about the SPITFIRE model, and by identifying potential means of mitigating them to a greater extent.</div
Supporting Data for “Revealed Preferential Short-Range Anion Ordering in Disordered RbM<sub>2</sub>O<sub>5</sub>F (M = Nb, Ta) Pyrochlore-Type Oxyfluorides”
No full textInternational audienceThis is the Supporting Dataset for the manuscript “Revealed Preferential Short-Range Anion Ordering in Disordered RbM2O5F (M = Nb, Ta) Pyrochlore-Type Oxyfluorides”. DOI: https://doi.org/10.1021/acs.inorgchem.5c00615The dataset comprises the following sections:Powder X-ray diffraction data. (directory)High-field solid-state nuclear magnetic resonance spectroscopy data. (directory)Steps for building and generating structural configurations from the unit cell of RbNb2O5F . (directory)First principle calculations data. (directory)Python scripts used to simulate the theoretical NMR spectra. (directory)Python scripts and raw numerical data for all figures included in the main manuscript and the Supporting Information. (directory)</p
Leveraging ecosystems responses to enhanced rock weathering in mitigation scenarios
No full textInternational audienceAbstract Carbon dioxide removal (CDR) is deemed necessary to attain the Paris Agreement’s climate objectives. While bioenergy with carbon capture and storage (BECCS) has generated substantial attention, sustainability concerns have led to increased examination of alternative strategies, including enhanced rock weathering (EW). We analyse the role of EW under cost-effective mitigation pathways, by including the CDR potential of basalt applications from silicate weathering (geochemical CDR) and enhanced ecosystem growth and carbon storage in response to phosphorus released by basalt (biotic CDR). Using an integrated carbon cycle, climate and energy system model, we show that the application of basalt to forests could triple the level of carbon sequestration induced by EW compared to an application restricted to croplands. EW also reduces the costs of achieving the Paris Agreement targets as well as the reliance on BECCS. Further understanding requires improved knowledge of weathering rates and basalt side-effects through field testing
Evidence of Alveolar Macrophage Metabolic Shift Following Stereotactic Body Radiation Therapy -Induced Lung Fibrosis in Mice
No full textInternational audienceRadiation-induced pneumopathy is the main dose-limiting factor in cases of chest radiation therapy. Macrophage infiltration is frequently observed in irradiated lung tissues and may participate in lung damage development. Radiationinduced lung fibrosis can be reproduced in rodent models using whole thorax irradiation but suffers from limits concerning the role played by unexposed lung volumes in damage development. Methods and Materials: Here, we used an accurate stereotactic body radiation therapy preclinical model irradiating 4% of the mouse lung. Tissue damage development and macrophage populations were followed by histology, flow cytometry, and single-cell RNA sequencing. Wild-type and CCR2 KO mice, in which monocyte recruitment is abrogated, were exposed to single doses of radiation, inducing progressive (60 Gy) or rapid (80 Gy) lung fibrosis. Results: Numerous clusters of macrophages were observed around the injured area, during progressive as well as rapid fibrosis.The results indicate that probably CCR2-independent recruitment and/or in situ proliferation may be responsible for macrophage invasion. Alveolar macrophages experience a metabolic shift from fatty acid metabolism to cholesterol biosynthesis, directing them through a possible profibrotic phenotype. Depicted data revealed that the origin and phenotype of macrophages present in the injured area may differ from what has been previously described in preclinical models exposing large lung volumes, representing a potentially interesting trail in the deciphering of radiation-induced lung damage processes. Conclusions: Our study brings new possible clues to the understanding of macrophage implications in radiation-induced lung damage, representing an interesting area for exploration in future studies.</p
Speciation of uranium and radium during the treatment of acidic waters from legacy-mine (Le Cellier, France)
No full textInternational audienceThe knowledge of aqueous speciation of uranium and radium in mining context is important for the modelling strategies based on reactive transport. The use of thermochemical databases allows accessing to theoretical speciation when the water compositions are known. If the usual concentration of radium in natural or anthropized waters is too low to have access to speciation experimentally, this can be achieved for uranium(VI), e.g. using time-resolved laser-induced fluorescence spectroscopy (TRLFS). In this work, theoretical radium and uranium inorganic and organic speciation were calculated using the water compositions collected in the legacy-mine site of Le Cellier (Lozère, France) currently under monitoring after its closure and decommissioning, and database file extracted from the Prodata database for the PhreeqC and Orchestra codes. We also have measured TRLFS uranium spectra, which allows monitoring the uranium(VI) evolution from sulphate-like UO2(SO4)n2–2n complexes, at the beginning of the treatment, to characteristic CanUO2(CO3)3(4–2n)- complexes towards the end of the treatment, with an expected decrease of the total uranium concentration. Inorganic thermodynamic calculations are in excellent agreement with the spectroscopic attributions all along the treatment, whatever the speciation code used. The influence of natural organic matter, as part of the dissolved organic carbon outside of the legacy-mine perimeter, cannot be ruled out but is not straightforward to ascertain. The effluent seems only to disturb slightly the uranium speciation in the local stream from UO2CO3(aq) to CanUO2(CO3)3(4–2n)- due to calcium increase