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Unique role of BSF glass in overcoming conventional glass-ceramic limitations in BNT for enhanced energy storage
No full textInternational audienceThis study reveals a departure from typical behavior in glass-ceramics, namely that the addition of glasses reduces dielectric polarization owing to their low dielectric character. Notably, incorporating a distinct relaxor-like class of glass (BSF) into pristine Bi0.5Na0.5TiO3 (BNT) ceramics significantly bolstered their energy storage capabilities. The latter alters the ferroelectric response, yielding slimmer P-E loops, a higher maximum polarization, and a substantially greater Wrec. Optimal compositions (2–4 wt% BSF) achieve 132.5 mJ/cm3 with 70 % peak efficiency, outperforming the 42.4 mJ/cm3 at 42 % efficiency for BNT. An interplay of elemental diffusion, interfacial polarization, and microstructural refinement promotes reversible domain switching, resulting in these enhancements. Possible field-induced polarization saturation at higher BSF contents gives rise to an exceptionally high Pmax (42.7 μC/cm2), demonstrating high polarizability levels for a glass-ceramic composite. This work highlights the unique role of the BSF glass in overcoming conventional limitations and offers a tunable route to high-efficiency, sustainable energy storage materials with potential applications in multifunctional technologies and devices
Mapping ESG-Driven sustainable development: A retrospective review and future research agenda
No full textInternational audienceThis present article conducts a bibliometric review and content analysis of the current body of research on environmental, social, and governance (ESG) performance. The present review aimed to provide a retrospective overview of ESG performance research within financial, non-financial, and mixed contexts. We followed PRISMA guidelines to ensure the inclusion of all eligible research papers, and obtained a sample of 169 articles selected from high-quality journals indexed in the Scopus database. Our contribution to the literature consists on investigating research trends and co-citation analysis and identified six main research thematic areas of ESG performance within financial, non-financial, and mixed contexts: (1) ESG Performance-Financial performance nexus, (2) sustainability governance-related performance, (3) Gender diversity and ESG performance, (4) ESGrelated disclosures and Rating, (5) Environmental impacts and carbon emissions and (6) Environmental uncertainty and Performance assessment. We reveal emerging research gaps and identify important potential avenues for further exploration. Our study provides valuable insights for practitioners, academics and policymakers to ensure ESG integration and effectiveness while achieving profitability and sustainability in the business landscape.</div
Marine litter, microplastic pollution and organic additives assessments in polar areas through an opportunistic cruise ship-based approach
No full textInternational audienceThis study presents findings from the opportunistic cruise, which performed microplastic and chemicalcontaminant sampling in surface waters, sediments, and ice in a sector of the western Arctic and the southwesternpart of the Antarctic Peninsula. Microplastics were detected in 100 % of the samples. Floating microplasticdensities (100–5000 μm) reached up to 314,251 items/km2 in Antarctica and 63,593 items/km2 in theArctic. The smallest particles (100–300 μm) dominated in southwestern Antarctic Peninsula (97 %) where thefibers (80 %) and fragments (19 %) were the main components. In the eastern Arctic, the two size classes(100–300 μm and 300–1000 μm) were more evenly distributed (58 % and 40 % respectively) and polymer diversity.Sediment microplastic concentrations were higher in the Arctic (up to 470 items/kg) compared tosouthwestern Antarctic Peninsula (maximum 399 items/kg). OrganoPhosphate Esters and PhthAlate Esters werealso measured for the first time in southwestern Antarctic Peninsula seawater (35.18 ±18.31 ng/L and 72.68 ±39.71 ng/L, respectively) and ice (50.44 ±24.79 ng/L and 16.72 ±11.46 ng/L, respectively). This studydemonstrates the utility of cruise ship-based sampling for monitoring remote regions and it contributes criticalbaseline data for global microplastic assessments.Cette étude présente les résultats d’une campagne opportuniste menée à bord d’un navire, au cours de laquelle des échantillonnages de microplastiques et de contaminants chimiques ont été réalisés dans les eaux de surface, les sédiments et la glace, dans un secteur de l’Arctique occidental et dans la partie sud-ouest de la péninsule Antarctique. Des microplastiques ont été détectés dans 100 % des échantillons. Les densités de microplastiques flottants (100–5000 µm) ont atteint jusqu’à 314 251 particules/km² en Antarctique et 63 593 particules/km² dans l’Arctique. Les plus petites particules (100–300 µm) dominaient dans la région sud-ouest de la péninsule Antarctique (97 %), où les fibres (80 %) et les fragments (19 %) constituaient les principaux types de particules. Dans l’Arctique oriental, les deux classes de taille (100–300 µm et 300–1000 µm) étaient plus équitablement réparties (58 % et 40 % respectivement), avec une plus grande diversité de polymères. Les concentrations de microplastiques dans les sédiments étaient plus élevées dans l’Arctique (jusqu’à 470 particules/kg) que dans la région sud-ouest de la péninsule Antarctique (maximum de 399 particules/kg). Des esters organophosphorés et des esters de phtalates ont également été mesurés pour la première fois dans l’eau de mer de la région sud-ouest de la péninsule Antarctique (35,18 ± 18,31 ng/L et 72,68 ± 39,71 ng/L, respectivement) ainsi que dans la glace (50,44 ± 24,79 ng/L et 16,72 ± 11,46 ng/L, respectivement). Cette étude démontre l’intérêt des prélèvements réalisés à partir de navires de croisière pour le suivi des régions éloignées et apporte des données de référence essentielles pour les évaluations globales des microplastiques
One pot synthesis of ZnO nanoparticle/mesoporous silica nanocomposite for photocatalysis
No full textInternational audienceMetal oxide materials, such as ZnO, have attracted considerable interest in photocatal-ysis due to their ability to generate reactive species under UV irradiation, which are useful for the degradation of organic or inorganic pollutants. However, the efficiency of photocatalysis re-lies on the intrinsic properties of the photocatalyst, such as its specific surface area or stability, or even aggregation when it is in the form of nanoparticles. To address these issues, we synthesized and thoroughly characterized ZnO nanoparticles confined in a mesoporous silica matrix. Several synthesis parameters were investigated, including the method of silica synthesis, the nature of the zinc precursor and the calcination temperature. The resulting materials exhibited a large specific surface area, and nanoparticles of 2 nm were homogeneously dispersed within the silica matrix. The optical properties, UV–visible absorption and photoluminescence, were examined and photocatalytic properties were evaluated through the photoreduction of Cr(VI)
Le generazioni future nella Carta dell’Ambiente: una causa in piena espansione, un diritto in ritardo
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Quantification of four classes of amphiphilic surfactants by solid phase extraction and spectrophotometric detection at nanomolar levels: environmental applications
No full textInternational audienceSurfactants are natural and anthropogenic compounds commonly found in all environmental compartments and can influence cloud formation due to their surface-active properties. In this work, a new method for the sensitive and selective quantification of 4 different classes of amphiphilic surfactants was developed, based on a new solidphase extraction (SPE) procedure with a graphitized carbon black sorbent and optimized spectrophotometric methods using commercial ion-pair reagents and liquid-liquid extraction. The sequential elution used in the SPE step enabled separate quantification of cationic, non-ionic, weak anionic and strong anionic surfactants. The spectrophotometric methods of detection of all classes of surfactants were optimized. A new method was developed for strong anionic surfactants using Toluidine blue O. Significant improvements were also made to existing methods for weak anionic and non-ionic surfactants using methylene blue and iron thiocyanate, respectively. Limits of detection of 0.08, 0.076, 0.91 and 0.20 nmol were achieved for cationic, non-ionic, weak anionic and strong anionic surfactants, respectively. A classification according to the acidity of the anionic group was proposed to distinguish synthetic surfactants (strong acids) from biosurfactants (weak acids). Issues related to interfering species, losses during filtration steps were also addressed, and a new filtration method with polyethylene frits was demonstrated to improve surfactants recoveries for aerosol analysis, with recoveries above 80 % for all types of surfactants. The procedure was applied to real environmental samples, including seawater and freshwater samples, aerosols extracts, and cloud water. Surfactants were successfully detected in all samples, with total concentrations between 12.1 nM and 495 nM for aqueous samples and between 48.4 pmol m -3 and 443 pmol m -3 for aerosol samples. Anionic surfactants were found to be the major constituents in all environmental matrices, but low concentrations of cationic and non-ionic surfactants were also detected in several samples
Micro-scale investigation of the role of fabric on internal stability of gap-graded soils
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Metrological concepts applied to Total Alkalinity measurements in seawater: reference materials, inter-laboratory comparison and uncertainty budget
No full textInternational audienceAbstract. Total alkalinity (TA) measurements in seawater are crucial for characterizing and monitoring the oceanic carbonate system. While international best practices and guidelines exist, the field still lacks widely available traceable reference materials and a well-established uncertainty budget of the measurement method. In this study, we applied key metrological principles – development of reference materials, inter-laboratory comparison and uncertainty quantification – to TA measurements. We developed two reference materials, including an artificial material with a rigorously characterized reference value and an associated uncertainty budget, being traceable to the International System of units (SI). These materials were tested in an inter-laboratory comparison involving five laboratories and demonstrated the applicability of the reference materials developed for quality control. Additionally, we established an uncertainty budget for the TA measurement method using two metrological approaches. The resulting expanded uncertainty was 5 µmol kg−1 (with a coverage factor k=2) in TA, approaching the 4 µmol kg−1 target set by the Global Ocean Acidification Observing Network for climate monitoring. These findings mark a significant step toward improving the quality and comparability of TA measurements, thereby strengthening long-term ocean carbonate system monitoring