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The core-shell approach for thermally conductive and electrically insulating polymer nanocomposites: A review
No full textInternational audienceThe development of new high-performance materials in the field of polymercomposites is becoming increasingly challenging as the requirements forreal-life applications evolve rapidly. In particular, the issue of heat dissipationin a multitude of devices has become a matter of critical importance due tothe ever-increasing compaction of electronic devices and the significantgrowth in power density stored in batteries. This calls for the development ofnovel solutions to enhance heat dissipation while preserving electricalinsulation properties, particularly in light of safety concerns. In this context,polymer nanocomposites can play a significant role, as the incorporation ofspecific fillers can markedly improve their intrinsic properties, namely, lowelectrical conductivity, lightweightness, processability, and low cost. Newfillers based on a core–shell structure have recently emerged. They aretypically nanoscopic in size and synthesized through fine chemical processesto optimize their performance and ensure optimal cohesion with the polymermatrix. Nanocomposites based on core–shell nanofiller yield remarkable andhighly promising outcomes, often exceeding the state of the art. This reviewarticle presents a comprehensive overview of these nanostructures and theirapplications, elucidating their significance and results, and discusses theirrole in achieving optimal heat dissipation.Le développement de nouveaux matériaux à hautes performances dans le domaine des composites polymères devient de plus en plus difficile car les exigences des applications réelles évoluent rapidement. En particulier, la question de la dissipation de la chaleur dans une multitude d'appareils est devenue d'une importance cruciale en raison de la densification des composants, de la miniaturisation des appareils électroniques et de l'augmentation significative de la densité de puissance stockée dans les batteries. Il est donc nécessaire de développer de nouvelles solutions pour améliorer la dissipation de la chaleur tout en préservant les propriétés d'isolation électrique, en particulier à la lumière des préoccupations en matière de sécurité. Dans ce contexte, les nanocomposites polymères peuvent jouer un rôle important, car l'incorporation de charges spécifiques peut améliorer sensiblement leurs propriétés intrinsèques, à savoir leur faible conductivité électrique, leur légèreté, leur facilité de mise en œuvre et leur faible coût. De nouvelles charges basées sur une structure cœur-coquille sont apparues récemment. Elles sont généralement de taille nanoscopique et synthétisées par des procédés chimiques fins afin d'optimiser leurs performances et de garantir une cohésion optimale avec la matrice polymère. Les nanocomposites basés sur des nano-charges de type cœur-coquille donnent des résultats remarquables et très prometteurs, dépassant souvent l'état de l'art. Cet article présente une vue d'ensemble de ces nanostructures et de leurs applications, en élucidant leur importance et leurs résultats, et discute de leur rôle dans l'obtention d'une dissipation thermique optimale
Procédé d'extraction par ancrage puis traction du faisceau électrochimique d'accumulateurs électrochimiques hors d'usage et/ou en fin de vie, réalisé individuellement ou par module de batterie ou par pack-batterie, en vue de son(leur) recyclage,
No full textDecarbonizing the cement industry is crucial for reducing CO<sub>2 </sub> emissions: Myth or reality?
No full textInternational audienceThe cement production contributes to about ~8% (≈2.5 gigaton by the year) of total anthropogenic CO2 emissions in the world. About 2/3 of these emissions are related to limestone calcination during cement clinker fabrication using mainly limestone, clay and silica sand. In this way, decarbonation of this industry is therefore a key challenge for a reduction of CO2 emissions. In this communication letter, an innovative chemical process is reported in order to avoid the CO2 emissions related to limestone calcination process. In effect, limestone (CaCO3) calcium source can be previously transformed into portlandite mineral (Ca(OH)2). In this manner, if the limestone is replaced by engineered portlandite, the cement clinker production will only reject vapor water during calcium silicates formation at high temperature as simplified for tri-calcium silicate: 3 Ca(OH)2 + SiO2 →3CaO.SiO2 + 3H2Ovapor (innovative reaction.In this experimental-technological study (TRL close to 2), portlandite production from limestone concerns well-known chemical reactions and the use of conventional reactants (e.g., HCl and NaOH). Acid reactant in order to extract calcium in solution (CaCO3 + 2HCl → Ca2+ + 2Cl- + H2 O + CO2(gas) (unit or reactor 1) and soda reactant to sequester simultaneously the produced carbon dioxide by chemisorption process (CO2(gas) + 2NaOH → CO3-2 + 2Na+ + H2O) leading to a carbonated solution (unit or reactor 2). Soda solutions are also utilized to produce portlandite from calcium solution (Ca2+ + 2Cl- + 2NaOH → Ca(OH)2 + 2NaCl). Portlandite mineral is then recovered from slurry by simple settling and water washing to remove residual soHdium chloride. Moreover, alkaline-carbonate solution obtained in reactor 2 by CO2 chemisorption process can be utilized to produce magnesite (MgCO3) “the most stable carbonate under Earth surface conditions” via indirect carbonation of Mg-silicates minerals or other stable carbonates. In this study, all main chemical reactions at the lab scale were optimized/characterized by Raman spectroscopy in real-time, X-ray diffraction and FESEM. In summary, this basic technology research (≈TRL 2) offers a realistic possibility/process to produce low-carbon cement and concrete by using the current existing technologies at the industrial scale
Continuous biocatalysis with wall-immobilized enzymes in milli-structured reactors
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Correlation of acid sites with morphology of layered silicates
No full textInternational audienceAcid sites of clay minerals are active to catalyze numerous organic reactions. Previous studies had focused on the types and strength of these sites by correlating them with acid, pillaring or heat treatments, but the relation of acid sites with clay mineral morphology is not well understood. In this study, the synthesis of samples havingsimilar chemical composition and structure, but different morphology characteristics was realized. The surface of samples was characterized by low-pressure argon adsorption at 77 K. The acid sites were probed by thermaldesorption of 2-phenylethylamine. Three sites of different acid strength were identified. Whereas the assignment of these sites to basal and edge surfaces remains debatable, the method of thermal desorption of 2-phenylethylamine could clearly distinguish different sites related to homogenous and heterogeneous surfaces
Appréhender les effets de l’IA dans les organisations pour une psychologie du travail du futur
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A novel fluorine-free lithium salt derived from malononitrile for electrolyte applications in liquid and solid-state batteries
No full textInternational audienceThe transition to clean energy heavily relies on lithium-ion batteries, known for their high energy density and long lifespan. However, the use of fluorinated salts such as LiPF and LiTFSI in commercial cells raises environmental concerns, leading to increased efforts to develop fluorine-free alternatives. In this study, we present the synthesis of lithium (1-naphthalenesulfonyl)-dicyanomethide (LiNPDM), a novel fluorine-free salt containing a dicyanomethide moiety and a naphthalene group, obtained in three steps from naphthalene sulfonate. For comparison, its trifluoromethanesulfonimide analogue (LiNPTFSI) was also prepared. The electrochemical performance of both salts were studied in conventional liquid electrolyte solvents (EC:DMC) and polycarbonate-based solid polymer electrolytes (SPEs). Although LiNPDM shows a narrower electrochemical stability window, attributed to cyano group oxidation at 4.0 V vs Li/Li, its conductivity performance matched those of its fluorinated analogue LiNPTFSI, both in conventional liquid electrolytes (3.5 mS∙cm) and SPEs (∼ 1 × 10 S∙cm at 80°C). These results suggest that the dicyanomethide functional group is a promising fluorine-free alternative to the conventional trifluoromethylsulfonimide group
Energy-Efficient Neuromorphic RF Localization using Analog Spiking Neurons
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Uncertainties in future ecosystem services under land and climate scenarios: The case of erosion in the Alps
No full textInternational audienceHow ecosystems will provide ecosystem services in the future given uncertain changes in climate and land use is an open question that challenges decision-making on adaptation to climate change. Prospective assessments of ecosystem services should carefully include and communicate the sources of uncertainties that affect the predictions. We used the ecosystem service of soil protection against erosion in the Maurienne Valley (French Alps) as a case study to illustrate how several sources of uncertainties can be integrated into an assessment of future ecosystem service supply. We modeled future erosion rates in the Maurienne Valley for years 2020 and 2085 using the Revised Universal Soil Loss Equation (RUSLE) and six climatic and socioeconomic scenarios. We quantified how the ecosystem service supply will be likely affected by climate and land-use change, separately and jointly. We assessed the effects of different sources of uncertainty on projected erosion rates: scenarios, climate models choice, and methods to parametrize the ecosystem service model. Land-use change increased erosion (+ 3.3 ton.ha-1.yr-1 on average, with significant increases in 81 % of the study site), while climate change contributed to a slight reduction (-0.21 ton.ha-1.yr-1 on average with significant decrease 20 % of the study site). The uncertainty of the ecosystem service model parameterization explained 93 % of the variance in erosion values. Furthermore, uncertainty linked to climate models and future scenarios contributed almost equally to the variability in the direction (positive or negative) of erosion change (41 % and 38 % respectively). The uncertainties surrounding the direction of future changes in ecosystem services come mainly from uncertainties in climate models and future scenarios rather than from uncertainties in the ecosystem service model parameters. Assessing the likelihood of future changes in ecosystem services helps prioritize locations where adaptation solutions are likely to be needed
A robust neural determination of the source-count distribution of the Fermi-LAT sky at high latitudes
No full textInternational audienceOver the past 16 years, the Fermi Large Area Telescope (LAT) has significantly advanced our view of the GeV gamma-ray sky, yet several key questions remain - such as the composition of the isotropic gamma-ray background, the origin of the Fermi Bubbles or the potential presence of signatures from exotic physics like dark matter. Addressing these challenges requires sophisticated astrophysical modeling and robust statistical methods capable of handling high-dimensional parameter spaces. In this work, we analyze 14 years of high-latitude () Fermi-LAT data in the range from 1 to 10 GeV using simulation-based inference (SBI) via neural ratio estimation. This approach allows us to detect individual gamma-ray sources and derive a list of significant gamma-ray emitters containing more than 98% of all sources listed in the Fermi-LAT Fourth Source Catalog (4FGL) with a flux (about a factor of three larger than the flux above which 4FGL is nearly complete), without any non-4FGL source detected in that flux range. Additionally, we reconstruct the source-count distribution in both parametric and non-parametric forms, achieving large agreement with previous literature results as well as those sources detected by our SBI pipeline. We also quantitatively validate our gamma-ray emission simulator via an anomaly detection technique, demonstrating that the synthetic data closely reproduces the complexity of the real observations