Search

International audience; The utilization of the anodic TiO 2 nanotube layers, with uniform Al 2 O 3 coatings of different thicknesses (prepared by atomic layer deposition, ALD), as the new electrode material for lithium-ion batteries (LIBs), is reported herein. Electrodes with very thin Al 2 O 3 coatings (∼1 nm) show a superior electrochemical performance for use in LIBs compared to that of the uncoated TiO 2 nanotube layers. A more than 2 times higher areal capacity is received on these coated TiO 2 nanotube layers (∼75 vs 200 μAh/cm 2) as well as higher rate capability and coulombic efficiency of the charging and discharging reactions. Reasons for this can be attributed to an increased mechanical stability of the TiO 2 nanotube layers upon Al 2 O 3 coating, as well as to an enhanced diffusion of the Li + ions within the coated nanotube layers. In contrast, thicker ALD Al 2 O 3 coatings result in a blocking of the electrode surface and therefore an areal capacity decrease. ■ INTRODUCTION During the last decade, TiO 2 nanomaterials have widely been studied as an alternative electrode material for lithium-ion batteries (LIBs). 1−15 TiO 2 has a higher lithiation potential (∼1.6 V vs Li/Li +) compared to that of the negative electrodes, such as graphite (∼0.1 V vs Li/Li +), and therefore enhances safety of the cells and provides a good capacity retention on cycling and a low self-discharge. 1−4 Furthermore, TiO 2 shows low volume changes of less than 4% upon reversible insertion and extraction of Li + in the lattice. However, TiO 2 also has a poor electrical conductivity and shows limited Li + uptake and slow Li + insertion kinetics. 1−4 To overcome these drawbacks, nanostructured TiO 2 , such as mesoporous microspheres, 5 nanowires, 6,7 nanoparticles, 8 nanoflakes, 9 or TiO 2 nano-tubes, 1−4,10 produced via different methods have been considered as anodes due to the larger specific surface area. Although most of these structures are randomly oriented and have to be deposited on the back contact of the electrode, self-organized TiO 2 nanotube layers produced by electrochemical anodization of the Ti substrates consist of straight and vertically aligned nanotubes in direct electrical contact with the underlying Ti substrate. 16 Another advantage of the vertically aligned nanotube layers is a direct diffusion path for the Li + ions, resulting in a superior electrochemical performance. 11 To further increase the capacity and conductivity of the TiO 2 nanotubes for their use in LIBs, they have been decorated or coated with other metals and metal oxides, with higher conductivities and capacities, for example, Ag, 17 Cu 6 Sn 5 , 18 Fe 2 O 3 , 19 SnO, 20 SnO 2 , 21,22 or ZnO. 23 Another advantage of these composite structures is that due to their hollow tubular architecture they can bear volume variations upon battery cycling without mechanical failure. Among the various methods that can be used for the coating and decoration of the TiO 2 nanotube layers, atomic layer deposition (ALD) has been the only method that creates uniform coatings of the nanotube walls from inside as well as outside, with a precise control of the coating thickness according to the deposition cycles. 24−26 However, although several reports can be found on utilization of the ALD coatings of different materials to modify the electrodes for lithium-ion battery application, 27−33 only one publication reports on the use of ALD to coat an anode prepared from an anodic TiO 2 nanotube layer with ZnO. 23 Usually, passivation layers on the electrode surfaces (solid electrolyte interphase (SEI)) are formed via decomposition of

International audience; Phase properties of gases adsorbed in small nanopores are mainly determined by the pore size and shape as well as the structural heterogeneity of the adsorbate. Here we analyze the evolution of the melting mechanism that occurs in pores

International audience; Alumina catalysts are frequently used in refineries for the hydrotreatment of heavy petroleum fraction that are enriched in asphaltenes. The transport of real and model asphaltenes molecules through powder and alumina's extrudates treated or not at 150°C to remove or not surfaceadsorbed water was studied. The kinetics and isotherms of adsorption at 298 K were obtained by the solution depletion method. Calorimetric experiments were also investigated. The kinetic is faster on the powder than on the alumina extrudates where the equilibrium is reached after 24 hours (against 1 hour for the powder) due to mass transfer limitation. The capacity of adsorption of model asphaltenes on untreated powder and extrudates is comparable around 1.1 and 1.2 mg.m-2 and increases with the heat treatment due to water removal. Both adsorption strength and capacity of real asphaltenes on alumina is lower compared to the model asphaltene molecule which could be explained by the strong interaction between the acidic function of the model molecule and the alumina surface. The calorimetric study in absence of alumina shows the dimerization of model asphaltene molecules. In presence of alumina, the enthalpy of adsorption of model and real asphaltenes on alumina is determined. The enthalpy of adsorption of model asphaltenes on treated powder is higher than on untreated powder meaning that more energetic sites are available (probably due to the release of water-occupied sites) and the curve obtained for treated powder suggests different adsorption sites. The enthalpy of adsorption of model asphaltene is higher for the treated extrudates but these results must be taken carefully because the kinetic of adsorption is very slow (24 hours) for extrudates. The effect of flow rate was studied by saturating an extrudate column with model asphaltene molecules. The adsorption increases as the flow rate decreases which could be explained by higher friction in the macropores leading to the release of weakly retained asphaltenes as the flow rate increases or by less intermediate pore blocking by asphaltenes as the flow rate and thus the pressure increases. This study shows that the transport of asphaltenes through porous alumina supports is a complex process depending on many parameters.

Since 2019, at the Institut de Recherche sur l'Enseignement des Sciences in Aix-Marseille Université, we have been running a workshop aimed at exploring solutions to the difficulties regularly encountered in interdisciplinary teaching. At regular intervals, this workshop brings together six teachers from different disciplines - from university and high school - who are simply given the time to present and explain to each other the specificities of the discipline they teach, using a basic categorial grid to guide analysis and enable comparison. However, our initial findings indicate that the primary beneficiary of these interdisciplinary encounters is disciplinary teaching itself. In fact, this introspective and collective work has brought to light fundamental implicits, specific or common, to these disciplines that teachers were unaware of; that they had never shared with their students; and that they identified as the source of hitherto unspeakable difficulties encountered by many of them. The hypothesis defended here is therefore that - through an effect of analogies and contrasts - interdisciplinary dialogue can be a formidable tool for reinforcing and clarifying disciplinary teaching, and could play a key role in teacher training., Depuis 2019, au sein de l’Institut de Recherche sur l’Enseignement des Sciences d’Aix-Marseille Université, nous animons un atelier visant à explorer des solutions aux difficultés régulièrement rencontrées dans l’enseignement interdisciplinaire. Cet atelier réunit à intervalles réguliers six enseignants de disciplines différentes — de l’université et du lycée — auxquels est simplement donné le temps de présenter et expliquer les uns aux autres les spécificités de la discipline qu’ils enseignent, à l’aide d’une grille catégorielle élémentaire, guidant l’analyse et permettant la comparaison. Or, nos premières conclusions indiquent que le premier bénéficiaire de ces rencontres interdisciplinaires est l’enseignement disciplinaire lui-même. De fait, ce travail introspectif et collectif a fait émerger des implicites fondamentaux spécifiques ou communs à ces disciplines dont les enseignants n’avaient pas conscience ; qu’ils n’avaient jamais partagé avec leurs élèves ; et qu’ils ont identifié comme la source de difficultés jusque-là inexprimables rencontrées par nombre d’entre eux. L’hypothèse défendue ici est donc que — par effet d’analogies et de contrastes — le dialogue interdisciplinaire peut être un formidable outil de renforcement et de clarification de l’enseignement disciplinaire, qui pourrait jouer un rôle clé dans la formation des enseignants.

International audience; The temporal and spatial evolution of dispersed media is a fundamental problem in a widerange of physicochemical systems, such as emulsions, suspensions or aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore subject to the influence of gravity which determines the sedimentation rate of their dispersed phase. This effect can be dominant and prevent a detailed study of the phenomena occurring between the constituents themselves, such as the coalescence of drops in emulsions, the evaporation of droplets or the flocculation in suspensions. In this context, the Centre National d'Etudes Spatiales (CNES) has recently supported the development of a new instrument to produce populations of droplets, a few micrometers in radius, under controlled conditions with the objective of allowing a detailed study of their properties in microgravity conditions. The principle of this instrument is to generate, by a fast compression/expansion of air, populations of water droplets and to track their evolution by optical scanning tomography in transmission mode within a volume of approximately 2 mm3. Parabolic flight experiments have shown the possibility to generate and accurately follow the evolution of populations of several hundred droplets for more than 20 seconds. The first experimental results show that it is possible to study their evaporation kinetics or their motion when imposing Von Karman swirling flows to air. This work is part of the AEROSOL project of DECLIC-EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming.

International audience; We present the results of extensive fully atomistic molecular dynamics (MD) simulations of tetracosane (C24H50) bilayer and trilayer systems adsorbed onto the basal plane of graphite. At low temperature, both layers of the bilayer exist in well-defined solid phases. With increasing temperature, the system exhibits separated smectic phases that eventually lead to melting. During this process, we observed a strong interlayer translational correlation and mobility between layers; however, the upper layer presents more intra- (chain) and intermolecular disorder because of a lack of confinement and a greater distance to the graphite substrate. Simulations of the perpendicular trilayer patch show that gauche defects provide the main mechanism for spreading of the bottom and outer perimeter of the patch in the solid, leading to the ultimate collapse of the patch with increasing temperature and formation of a flat (parallel) trilayer that melts at a higher temperature than the bilayer structure. The wide variety of structural order parameters, thermodynamic functions, and probability distributions we employed provide a clear picture of the roles of gauche defects, confinement, and interlayer correlation in the phases and phase transitions exhibited by these confined organic layers.

International audience; ! abstract The mechanisms of methane adsorption in (i) homogeneous carbon slit pores of widths between 1 nm and 2 nm and (ii) heterogeneous MOF pores of similar unit cell sizes have been compared. We discuss the mechanism of layering transition in subcritical conditions, for temperatures between 80 K and 180 K. The layer formation is strongly temperature-dependent. In slit pores it varies from a sharp adsorption at low temperatures to a more continuous uptake at higher temperatures. The pore size defines the number of adsorbed layers: the 1 nm pore allows adsorption of 2 layers while the 2 nm pore allows adsorption of 5 layers of methane molecules. We compare this behavior with the mechanism of adsorption in two MOFs, IRMOF-1 and IRMOF-16, with strongly heterogeneous walls (both structurally and energetically). This comparison allows us to discuss separately the influence of wall topology and intermolecular interactions on the mechanism of layering.

International audience; Design of efficient solar energy-conversion materials has attracted much interest in the last decades. Among these materials, copper-based semiconducting chalcogenides have been employed as alternatives for copper indium gallium selenide (CIGS) thin-film solar cells due to their low toxicity and earth-abundant absorber components. In the present manuscript, structural, electronic, topological, and optical properties of ternary chalcogenide CuSbS2, Cu3SbS3, and Cu3SbS4 have been investigated using the full potential linear augmented plane wave (FP-LAPW) method. An indirect bandgap is observed for CuSbS2 with Eg = 1.178 eV and a direct bandgap is found for Cu3SbS3, and Cu3SbS4 with Eg = 1.283 and 1.0 eV, respectively. The valence band maximum (VBM) of CuSbS2, Cu3SbS3, and Cu3SbS4 are mainly predominated by a strong Cu-3d and S-3p orbitals hybridization. The conduction band of CuSbS2 and Cu3SbS3 are mainly characterized by Sb-5p orbital and S-3p orbital mixing. However, conduction band of Cu3SbS4 is dominated by the mixing of Sb-5s and S-3p orbitals. It is found that the Cu-S and Sb-S bonds lie in the transit closed-shell zone, between the typical ionic and covalent bonds. The optical properties of CuSbS2, Cu3SbS3, and Cu3SbS4 in terms of absorption coefficient, extinction coefficient, refractive index, and reflectivity have been investigated. The results show that the CuSbS2, Cu3SbS3, and Cu3SbS4 compounds have real potential to be used for solar-energy conversion.

International audience; The temporal and spatial evolution of dispersed media is a fundamental problem in a wide range of physico-chemical systems, such as emulsions, suspensions or aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore sensitive to buoyancy which determine s the rate of sedimentation of the dispersed phase . The latter usually prevent s a detailed study of the phenomena occurring between the constituents of aerosols , such as coalescence and evaporation of drops or flocculation of fine particles . The idea of this work is to generate with a fast compression/expansion of air, populations of water drop let s and to track their evolution by optical scanning tomography in transmission mode. Parabolic flights experiments have shown the possibility to generate and accurately follow the evolution of several hundred droplets for more than 20 seconds of microgravity within a 2 mm 3 volume . First results show that it is possible to study their evaporation kinetics as well as their motion when moving in a Von Karman swirling flow. This work is part of the AEROSOL project of DECLIC EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming.

International audience; In this work, a novel oxygen vacancy mediated 2D/2D g-C3N4/CeO2 S-scheme heterojunction was constructed through a hydrothermal method by combing carboxylated g-C3N4 (C-g-C3N4) with CeO2 sheets treated by hydrogen (CeO2-S-H2). The ratio of Ce 3+ /Ce 4+ in CeO2 was increased from 28.2% to 32.08% through hydrogen treatment, which further improved visible light absorption and charges separation efficiency of heterojunction. As a result, C-g-C3N4/CeO2-S-H2 heterojunction exhibited excellent CO2 reduction activity compared with pure C-g-C3N4 and CeO2. The highest CO yields in 8 h of 60%C-g-C3N4/CeO2-S-H2 was 2.41, 6.83 and 1.72 times that of pure C-g-C3N4, CeO2-S and CeO2-S-H2, respectively. Interestingly, the amount of CH4 generated by C-g-C3N4 was negligible. However, CH4 yields of 60%C-g-C3N4/CeO2-S-H2 reached 11.997 umol/g in 8 h. The results indicated that the introduction of oxygen vacancies can effectively enhance CH4 production, which can be used as a reference for the development of photocatalysts with high activity and selectivity. Simultaneously, the C-g-C3N4/CeO2-S-H2 heterojunction also demonstrated the good ciprofloxacin degradation activity. The possible S-scheme photocatalytic mechanism of C-g-C3N4/CeO2-S-H2 heterojunction was proposed. This study provides a new idea for the design of photocatalysts with high efficiency of converting carbon dioxide into solar fuels.

International audience

International audience; In this study, lychee-like TiO2@Fe2O3 microspheres with a core-shell structure have been prepared by coating Fe2O3 on the surface of TiO2 mesoporous microspheres using the homogeneous precipitation method. The structural and micromorphological characterization of TiO2@Fe2O3 microspheres has been carried out using XRD, FE-SEM, and Raman, and the results show that hematite Fe2O3 particles (7.05% of the total mass) are uniformly coated on the surface of anatase TiO2 microspheres, and the specific surface area of this material is 14.72 m2 g−1. The electrochemical performance test results show that after 200 cycles at 0.2 C current density, the specific capacity of TiO2@Fe2O3 anode material increases by 219.3% compared with anatase TiO2, reaching 591.5 mAh g−1; after 500 cycles at 2 C current density, the discharge specific capacity of TiO2@Fe2O3 reaches 273.1 mAh g−1, and its discharge specific capacity, cycle stability, and multiplicity performance are superior to those of commercial graphite. In comparison with anatase TiO2 and hematite Fe2O3, TiO2@Fe2O3 has higher conductivity and lithium-ion diffusion rate, thereby enhancing its rate performance. The electron density of states (DOS) of TiO2@Fe2O3 shows its metallic nature by DFT calculations, revealing the essential reason for the high electronic conductivity of TiO2@Fe2O3. This study presents a novel strategy for identifying suitable anode materials for commercial lithium-ion batteries.

International audience; We carry out random walk simulations on prototypical porous structures that are representative of actual hierarchical silica-based materials. The main throughput of the mesoscopic simulations proposed here is the tortuosity defined as the ratio of the fluid mean square displacements calculated in the absence and in the presence of the porous medium. This is a rigorous mathematical definition that has the advantage to be comparable to the ratio of self-diffusion coefficients for the bulk and confined fluid, which can be directly determined by means of diffusion experiments. Such tortuosity can also be compared with the ratio of bulk and effective electrical conductivities. These calculations are applied here to hierarchical materials such as those encountered in chromatography, membrane science or catalysis. The simulation results are compared to experimental data as well as to effective equations-such as Maxwell's equation-which are often invoked to infer tortuosity expressions based on effective mean field theories.

In this study, 20Li2O-60V2O5-(20 − x)B2O3-xBi2O3 (x = 5, 7.5, 10 mol%) glass materials have been prepared by the melt-quenching method, and the structure and morphology of the glass materials have been characterized by XRD, FTIR, Raman, and FE-SEM. The results show that the disordered network of the glass is mainly composed of structural motifs, such as VO4, BO3, BiO3, and BiO6. The electrochemical properties of the glass cathode material have been investigated by the galvanostatic charge-discharge method and cyclic voltammetry, and the results show that with the increases of Bi2O3 molar content, the amount of the VO4 group increases, and the network structure of the glass becomes more stable. To further enhance the electrochemical properties, glass-ceramic materials have been obtained by heat treatment, and the effect of the heat treatment temperature on the structure and electrochemical properties of the glass has been studied. The results show that the initial discharge capacity of the glass-ceramic cathode obtained by heat treatment at 280 °C at a current density of 50 mA·g−1 is 333.4 mAh·g−1. In addition, after several cycles of charging and discharging at a high current density of 1000 mA·g−1 and then 10 cycles at 50 mA·g−1, its discharge capacity remains at approximately 300 mAh·g−1 with a capacity retention rate of approximately 90.0%. The results indicate that a proper heat treatment temperature is crucial to improving the electrochemical properties of glass materials. This study provides an approach for the development of new glass cathode materials for lithium-ion batteries.

Thermoelectric materials have attracted extensive attention because they can directly convert waste heat into electric energy. As a brand-new method of alloying, high-entropy alloys (HEAs) have attracted much attention in the fields of materials science and engineering. Recent researches have found that HEAs could be potentially good thermoelectric (TE) materials. In this study, special quasi-random structures (SQS) of PbSnTeSe high-entropy alloys consisting of 64 atoms have been generated. The thermoelectric transport properties of the highest-entropy PbSnTeSe-optimized structure were investigated by combining calculations from first-principles density-functional theory and on-the-fly machine learning with the semiclassical Boltzmann transport theory and Green–Kubo theory. The results demonstrate that PbSnTeSe HEA has a very low lattice thermal conductivity. The electrical conductivity, thermal electronic conductivity and Seebeck coefficient have been evaluated for both n-type and p-type doping. N-type PbSnTeSe exhibits better power factor (PF = S2σ) than p-type PbSnTeSe because of larger electrical conductivity for n-type doping. Despite high electrical thermal conductivities, the calculated ZT are satisfactory. The maximum ZT (about 1.1) is found at 500 K for n-type doping. These results confirm that PbSnTeSe HEA is a promising thermoelectric material.

International audience; The hydrolytic stability of ionomer membranes is a matter of concern for the long-term durability of energy storage and conversion devices. Various reinforcement strategies exist for the improvement of the performances of the overall membrane. We propose in this article the stabilization of membranes based on aromatic ion conducting polymers (SPEEK and SPPSU) by the introduction of an electrospun mat of inexpensive PPSU polymer. Characterization data from hydrolytic stability (mass uptake and dimension change) and from mechanical and conductivity measurements show an improved stability of membranes in phosphate buffer, used for enzymatic fuel cells, and in distilled water. The synergistic effect of the reinforcement, together with the casting solvent and the thermal treatment or blending polymers, is promising for the realization of high stability ionomer membranes.

International audience; The energetics of sulfur-carbon interaction are studied using thermo-desorption and immersion microcalorimetry experiments. Sulfur is incorporated in meso- and microporous carbons by impregnation either from the liquid phase or the vapor phase. Varying the temperature of impregnation enables to fill preferentially microporous domains (vapor impregnation) or both micro-meso-macro domains (liquid impregnation). The three carbons lead to similar immersion enthalpies per unit area for liquid sulfur. This suggests that they possess similar surface-liquid interactions and that liquid sulfur, below the polymerization temperature, wets the whole surface accessible to nitrogen.

International audience; The efficient storage and transportation of natural gas is one of the most important enabling technologies for use in energy applications. Adsorption in porous systems, which will allow the transportation of high-density fuel under low pressure, is one of the possible solutions. We present and discuss extensive grand canonical Monte Carlo (GCMC) simulation results of the adsorption of methane into slit-shaped graphitic pores of various widths (between 7 angstrom and 50 angstrom), and at pressures P between 0 bar and 360 bar. Our results shed light on the dependence of film structure on pore width and pressure. For large widths, we observe multi-layer adsorption at supercritical conditions, with excess amounts even at large distances from the pore walls originating from the attractive interaction exerted by a very high-density film in the first layer. We are also able to successfully model the experimental adsorption isotherms of heterogeneous activated carbon samples by means of an ensemble average of the pore widths, based exclusively on the pore-size distributions (PSD) calculated from subcritical nitrogen adsorption isotherms. Finally, we propose a new formula, based on the PSD ensemble averages, to calculate the isosteric heat of adsorption of heterogeneous systems from singlepore-width calculations. The methods proposed here will contribute to the rational design and optimization of future adsorption-based storage tanks.

International audience; Adsorption of mixtures of methane and methyl merkaptan in nanoporous carbon

International audience; Recently, porous organic crystals (POC) based on macrocycles have shown exceptional sorption and separation properties. Yet, the impact of guest presence inside a macrocycle prior to adsorption has not been studied. Here we show that the inclusion of trimethoxybenzyl-azaphosphatrane in the macrocycle cucurbit-[8]uril (CB[8]) affords molecular porous host-guest crystals (PHGC-1) with radically new properties. Unactivated hydrated PHGC-1 adsorbed iodine spontaneously and selectively at room temperature and atmospheric pressure. The absence of (i) heat for material synthesis, (ii) moisture sensitivity, and (iii) energy-intensive steps for pore activation are attractive attributes for decreasing the energy costs. 1 H NMR and DOSY were instrumental for monitoring the H 2 O/I 2 exchange. PHGC-1 crystals are non-centrosymmetric and I 2-doped crystals showed markedly different second harmonic generation (SHG), which suggests that iodine doping could be used to modulate the non-linear optical properties of porous organic crystals.

International audience; The kinetics of spontaneous emulsification is investigated on aqueous pendant drops in paraffin oil. Optical microscopy in transmission mode is used for high-spatial-resolution image recording. The influence of a lipophilic surfactant (Span 80) and two water-soluble surfactants (CTAB and SDS) is investigated. As time runs, the drops interface turns opaque due to the formation of microstructures associated with spontaneous emulsification. The time evolution of this phenomenon is shown to depend upon temperature and surfactant concentration which leads to an overall shrinkage due to gradual water uptake and transport into paraffin oil. Spontaneous emulsification kinetics depends upon the chemical composition. Higher concentration of Span 80 and CTAB (resp. SDS) are shown to promote (resp. hinder) water transport. This work provides new insights into the understanding of spontaneous emulsification when combining the properties of non-ionic and ionic surfactants.

International audience; Aerosols are divided systems in which liquid and/or solid particles evolve in a continuous gas phase. They are naturally subject to the influence of gravity, which determines the settling speed of the particles they contain. Aerosols have many applications in the pharmaceutical and cosmetic industries (inhalers, sprays), in metallurgy (spray drying) and in agriculture (pesticides). From an academic point of view, they are the subject of intense research activity. The description of their evolution is, for example, a major issue in climatology. With global warming, more water is evaporatingin the air resulting in more cloud formation and a higher importance of cloud microphysics in the understanding of the climate evolution. In this context, CNES has recently supported the development of a new instrument allowing not only to produce aerosols under controlled thermodynamicconditions but also to follow their evolution in microgravity. This work presents results of parabolic flight experiments. It demonstrates the possibility of producing aerosols and to investigate their properties with optical microscopy for periods of about twenty seconds.

International audience; The temporal and spatial evolution of dispersed media is a fundamental problem in a wide range of physicochemical systems, such as emulsions, suspensions and aerosols. These systems are multiphasic and involve compounds of different densities. They are therefore subject to the influence of gravity which determines the sedimentation rate of their dispersed phase. This effect can be dominant and prevent a detailed study of the phenomena occurring between the constituents themselves, such as the coalescence of drops in emulsions, the evaporation of droplets or the flocculation in suspensions. In this context, the Centre National d'Etudes Spatiales (CNES) has recently supported the development of a new instrument to produce populations of droplets, a few micrometers in radius, under controlled conditions with the objective of allowing a detailed study of their properties in microgravity conditions. The principle of this instrument is to generate, by a fast compression/expansion of air, populations of water droplets and to track their evolution by optical scanning tomography in transmission mode within a volume of approximately 2 mm 3. Parabolic flight experiments have shown the possibility to generate and accurately follow the evolution of populations of several hundred droplets for more than 20 seconds. The first experimental results show that it is possible to study their evaporation kinetics or their motion when imposing Von Karman swirling flows. This work is part of the AEROSOL project of DECLIC-EVO supported by CNES and aims to help the understanding of cloud microphysics which remains a critical open problem in the context of global warming.

International audience; Adsorptive separation of propylene (C3H6) and propane (C3H8) may represent an energy-efficient alternative to conventional cryogenic distillation. In this perspective, a set of zeolitic adsorbents of LTA type structure (pure-silica zeolite (Si-LTA) and cation- (Na+, 33% of Li+, 50% of Mg2+ and 50% of Ca2+) containing zeolites) were prepared, then characterized using various techniques such as PXRD, gas adsorption measurement, TGA, XRF, SEM and EDX mapping. Thanks to an in-house manometric dosing setup coupled with a Tian-Calvet type microcalorimeter, the pure gas adsorption isotherms and their corresponding differential enthalpies of adsorption were measured at 303 K and for pressures up to 5 bar. To fit those adsorption data, the dual-site Langmuir was selected as the best fit model, and by using the Ideal Adsorbed Solution Theory (IAST), thermodynamic selectivities were determined. The mass transfer constants were also estimated by fitting, separately, the Linear Driving Force (LDF) and isothermal micropore diffusion models to adsorption kinetic curves, thus allowing kinetic type selectivities to be calculated. The combination of those selectivities reveals that the thermodynamic separation of C3H6 from C3H8 is highly favorable on CaNa-LTA, followed by its MgNa-LTA counterpart with IAST selectivities around 15 and 5, respectively. On the other hand, the monovalent cationic zeolites (i.e., Na- and LiNa-LTA) show a predominance of steric effects. Also, except for Si-LTA which shows a moderate kinetic separation, the studied materials are potential candidates, in the following order CaNa- > MgNa- > LiNa- > Na-LTA, for the separation of C3H6 from C3H8 by adsorption-based technologies.

Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the reactivity of metal–organic frameworks. In this work, various MOF‐808 (Zr) samples are synthesized and characterized with the final aim to understand how defects and/or platinum nanoparticle encapsulation act on the intrinsic and reactive properties of these MOFs. The reactivity of the pristine, defective and Pt encapsulated MOF‐808 is quantified with water adsorption and CO2 adsorption calorimetry. The results reveal strong competitive effects between crystal morphology and missing linker defects which in turn affect the crystal morphology, porosity, stability, and reactivity. In spite of leading to a loss in porosity, the introduction of defects (missing linkers or Pt nanoparticles) is beneficial to the stability of the MOF‐808 towards water and could also be advantageously used to tune adsorption properties of this MOF family., Defects and metal nanoparticle encapsulations have been shown to have significant impacts on structure, texture, morphology and reactivity of the synthesized MOFs. Control over defects creation and metal nanoparticle encapsulations can become useful avenues to adjust the properties of MOFs.

International audience

Two novel amorphous metal–organic frameworks (aMOFs) with chemical composition {[Zn2(MTA)]·4H2O·3DMF}n (UPJS-13) and {[Cd2(MTA)]·5H2O·4DMF}n (UPJS-14) built from Zn(II) and Cd(II) ions and extended tetrahedral tetraazo-tetracarboxylic acid (H4MTA) as a linker were prepared and characterised. Nitrogen adsorption measurements were performed on as-synthesized (AS), ethanol exchanged (EX) and freeze-dried (FD) materials at different activation temperatures of 60, 80, 100, 120, 150 and 200 °C to obtain the best textural properties. The largest surface areas of 830 m2 g−1 for UPJS-13 (FD) and 1057 m2 g−1 for UPJS-14 (FD) were calculated from the nitrogen adsorption isotherms for freeze-dried materials activated at mild activation temperature (80 °C). Subsequently, the prepared compounds were tested as adsorbents of greenhouse gases, carbon dioxide and methane, measured at high pressures. The maximal adsorption capacities were 30.01 wt% CO2 and 4.84 wt% CH4 for UPJS-13 (FD) and 24.56 wt% CO2 and 6.38 wt% CH4 for UPJS-14 (FD) at 20 bar and 30 °C.

This short review summarizes the improvements on biological fuel cells (BioFCs) with or without ionomer separation membrane. After a general introduction about the main challenges of modern energy management, BioFCs are presented including microbial fuel cells (MFCs) and enzymatic fuel cells (EFCs). The benefits of BioFCs include the capability to derive energy from waste-water and organic matter, the possibility to use bacteria or enzymes to replace expensive catalysts such as platinum, the high selectivity of the electrode reactions that allow working with less complicated systems, without the need for high purification, and the lower environmental impact. In comparison with classical FCs and given their lower electrochemical performances, BioFCs have, up to now, only found niche applications with low power needs, but they could become a green solution in the perspective of sustainable development and the circular economy. Ion exchange membranes for utilization in BioFCs are discussed in the final section of the review: they include perfluorinated proton exchange membranes but also aromatic polymers grafted with proton or anion exchange groups.

International audience; Flexible stimuli-responsive metal−organic frameworks have become promising candidates for numerous applications in gas-related technologies; however, the methods of fine tuning their responses are still limited and sought after. In this work, we demonstrate control over the adsorption properties of a flexible platform by incorporating halogen substituents (X = F, Cl, Br, I) into an eightfold interpenetrated isoreticular series [Zn(oba)(X-pip)] n (JUK-8X; X-pip = 4-pyridyl-functionalized benzene-1,3-dicarbo-5-halogenohydrazide; oba 2− = 4,4′-oxydibenzoic carboxylate). The introduced halogen atoms allow for precise tuning of CO 2 gate-opening pressures from p/p 0 = 0.08 for the parental JUK-8 to 0.78 for the chlorinefunctionalized JUK-8Cl. The presence of fluorine or chlorine substituent in the X-pip linker practically does not influence the maximum molar CO 2 uptake as compared to JUK-8, whereas larger bromine or iodine atoms increase this uptake by 59 and 48%, respectively. Utilizing in situ powder X-ray diffraction (PXRD) during CO 2 adsorption for a model JUK-8F, we propose a detailed mechanism of phase transitions including positions of the adsorbed gas molecules for the two loaded phases. Density functional theory calculations supported by in situ PXRD measurements at a saturation pressure shed light on the unusual CO 2 adsorption properties of JUK-8Br and JUK-8I. Overall, our report demonstrates the use of halogen interactions for the control of a gas-responsive system and provides insightful guidance for the further development of flexible, adaptable materials.

International audience; In this work, we studied the combination of nitrogen-doped carbon quantum dots (N-CQD), a hydroxide-ion conducting ionomer based on polysulfone (PSU) and polyaniline (PANI), to explore the complementary properties of these materials in high-performance nanostructured electrodes for the oxygen reduction reaction (ORR) in alkaline solution. N-CQD were made by hydrothermal synthesis from glucosamine hydrochloride (GAH) or glucosamine hydrochloride and N-Octylamine (GAH-Oct), and PSU were quaternized with trimethylamine (PSU-TMA). The nanocomposite electrodes were prepared on carbon paper by drop-casting. Furthermore, we succeeded in preparing PSU-TMA + PANI + GAH-Oct fibers by electrospinning. The capacitance of the electrodes was investigated by cyclic voltammetry and impedance spectroscopy, which gave similar trends. The ORR was investigated by linear sweep voltammetry at rotating disk electrode speeds between 250 and 2000 rpm in an oxygen-saturated 1 M KOH solution. Koutecky–Levich plots showed that four electrons were exchanged for nanocomposite electrodes containing CQD. The highest reduction currents were measured for the electrodes containing GAH-Oct. The Tafel plots gave the lowest slope and the most positive half-wave potential for PSU-TMA + PANI + GAH-Oct fibers. The best electrocatalytic activity of this electrode could be related to the high amount of graphitic nitrogen in GAH-Oct. Long-term cycling tests showed no significant modification of the onset potential, but a change of the current in the mass transport limited region, indicated the evolution of the microstructure of the nanocomposite ORR electrode modifying the mass transport conditions during the first 400 cycles before reaching stationary conditions. FTIR spectra were used to study possible electrode degradation after the ORR in 1 M KOH: the only change was due to the reaction of PANI emeraldine salt to emeraldine base, whereas the other constituents of the multiphase electrode did not show any degradation.

International audience; This work describes self-assembled monolayers (SAMs) of two ferrocene derivatives with twoanchoring groups (at the bottom and at the top of the SAM) deposited on ultra-flat templatestripped gold substrates by cyclic voltammetry and analyzed by complementary surfacecharacterization techniques. The SAM of each molecule is deposited by three differentprotocols: direct deposition (1 step), Click reaction on surface (2 steps) and reverse Clickreaction on surface (2 steps). The SAM structure is well-studied to determine the SAMorientation, SAM arrangement and ferrocene position within the SAM. Electron transferkinetics have also been performed which agree with the quality of each SAM. With the helpof two anchoring groups and Click-chemistry active functional groups, we have shown thatthe two molecules can be deposited by either end controlling the position of ferrocene. Wefurther investigated the involvement of the triazole five membered ring in the electrontransfer mechanism. We have found that a carbon spacer between ferrocene and triazoleimproves the SAM packing. This study enhances the understanding of tethering thiol and thiol acetate anchoring groups on gold by controlled orientation which may help in developmentof functional molecular devices requiring two anchoring groups.

Proton-conducting polymers, such as sulfonated poly(ether ether ketone) (SPEEK), are of great industrial interest. Such proton exchange membranes show high tendencies for water and water vapor uptake. The incorporation of water not only leads to mass and dimensional changes, but also to changes in conductivity by several orders of magnitude. Both properties highly impact the potential application of the materials and, therefore, have to be known precisely. As hydration is diffusion controlled, thin films may behave differently to bulk specimens. However, the determination of small mass changes occurring in thin-film samples is very challenging. In this work, a new measurement setup is presented to simultaneously characterize the mass change and the conductivity of thin polymer films. The mass change is measured by resonant piezoelectric spectroscopy (RPS) with a nanobalance, which is based on high-precision piezoelectric resonators operating in thickness-shear mode (TSM). The mass resolution of this nanobalance is ±7.9 ng. Electrochemical impedance spectroscopy and an interdigitated electrode array are used for conductivity measurements. The approach is validated by comparing two SPEEK films with different degrees of sulfonation (DS). The relative humidity (RH) in the measurement setup was changed stepwise within the range ∼ 2 %

A single crystalline layered semiconductor In1.2Ga0.8S3 phase was grown, and by intercalating p-aminopyridine (NH2-C5H4N or p-AP) molecules into this crystal, a new intercalation compound, In1.2Ga0.8S3·0.5(NH2-C5H4N), was synthesized. Further, by substituting p-AP molecules with p-ethylenediamine (NH2-CH2-CH2-NH2 or p-EDA) in this intercalation compound, another new intercalated compound—In1.2Ga0.8S3·0.5(NH2-CH2-CH2-NH2) was synthesized. It was found that the single crystallinity of the initial In1.2Ga0.8S3 samples was retained after their intercalation despite a strong deterioration in quality. The thermal peculiarities of both the intercalation and deintercalation of the title crystal were determined. Furthermore, the unit cell parameters of the intercalation compounds were determined from X-ray diffraction data (XRD). It was found that increasing the c parameter corresponded to the dimension of the intercalated molecule. In addition to the intercalation phases’ experimental characterization, the lattice dynamical properties and the electronic and bonding features of the stoichiometric GaInS3 were calculated using the Density Functional Theory within the Generalized Gradient Approximations (DFT-GGA). Nine Raman-active modes were observed and identified for this compound. The electronic gap was found to be an indirect one and the topological analysis of the electron density revealed that the interlayer bonding is rather weak, thus enabling the intercalation of organic molecules.

International audience; In this study, home-made amorphous TiO2 microspheres with good mono-dispersity and large numbers of mesopores on the surface were used as substrates. The intermediate microspheres were obtained by adding Co/Ni sources with different Co/Ni molar ratios in a water bath and making them react by water bath heating. By calcining the intermediate microspheres deposited on the TiO2 ones, a core–shell structured spherical CoTiO3/NiTiO3 inorganic composite pigment was prepared. The synthesized pigments were characterized by X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), laser particle size (LPS) analysis and colorimetry. The results show that when the calcination temperature is 800 °C and the Co/Ni molar ratio is 0.5:0.5, the pigments consist of a TiO2 core and outer ilmenite CoTiO3/NiTiO3 shell. Moreover, the surface of the product microspheres is smooth, and the particles are of regular sphericity with a uniform particle size of about 1.8 μm. The colorimetric analysis from the samples calcined at 800 °C shows color changes from yellow-green to dark green as the Co/Ni molar ratio increases (0.1:0.9 to 0.9:0.1). A Co/Ni molar ratio that is too high or too low results in the formation of by-products such as Co3O4 or NiO, respectively, which adhere to the product surface and affect the chromaticity of the product. This work has enabled the chromatic modulation of yellow-green inorganic pigments, providing a solution for the preparation of spherical inorganic pigments that are more suitable for industrial inkjet printing.

In this work we report the synthesis of the new ionomer poly(alkylene biphenyl butyltrimethyl ammonium) (ABBA) with a backbone devoid of alkaline-labile C-O-C bonds and with quaternary ammonium groups grafted on long side chains. The ionomer was achieved by metalation reaction with n-butyllithium of 2-bromobiphenyl, followed by the introduction of the long chain with 1,4-dibromobutane. The reaction steps were followed by 1H-NMR spectroscopy showing the characteristic signals of the Br-butyl chain and indicating the complete functionalization of the biphenyl moiety. The precursor was polycondensed with 1,1,1-trifluoroacetone and then quaternized using trimethylamine (TMA). After the acid catalyzed polycondensation, the stoichiometric ratio between the precursors was respected. The quaternization with TMA gave a final degree of amination of 0.83 in agreement with the thermogravimetric analysis and with the ion exchange capacity of 2.5 meq/g determined by acid–base titration. The new ionomer blended with poly(vinylalcohol) (PVA) or poly(vinylidene difluoride) (PVDF) was also characterized by water uptake (WU) and ionic conductivity measurements. The higher water uptake and ionic conductivity observed with the PVDF blend might be related to a better nanophase separation.

Since 2019, at the Institut de Recherche sur l'Enseignement des Sciences in Aix-Marseille Université, we have been running a workshop aimed at exploring solutions to the difficulties regularly encountered in interdisciplinary teaching. At regular intervals, this workshop brings together six teachers from different disciplines - from university and high school - who are simply given the time to present and explain to each other the specificities of the discipline they teach, using a basic categorial grid to guide analysis and enable comparison. However, our initial findings indicate that the primary beneficiary of these interdisciplinary encounters is disciplinary teaching itself. In fact, this introspective and collective work has brought to light fundamental implicits, specific or common, to these disciplines that teachers were unaware of; that they had never shared with their students; and that they identified as the source of hitherto unspeakable difficulties encountered by many of them. The hypothesis defended here is therefore that - through an effect of analogies and contrasts - interdisciplinary dialogue can be a formidable tool for reinforcing and clarifying disciplinary teaching, and could play a key role in teacher training.; Depuis 2019, au sein de l’Institut de Recherche sur l’Enseignement des Sciences d’Aix-Marseille Université, nous animons un atelier visant à explorer des solutions aux difficultés régulièrement rencontrées dans l’enseignement interdisciplinaire. Cet atelier réunit à intervalles réguliers six enseignants de disciplines différentes — de l’université et du lycée — auxquels est simplement donné le temps de présenter et expliquer les uns aux autres les spécificités de la discipline qu’ils enseignent, à l’aide d’une grille catégorielle élémentaire, guidant l’analyse et permettant la comparaison. Or, nos premières conclusions indiquent que le premier bénéficiaire de ces rencontres interdisciplinaires est l’enseignement disciplinaire lui-même. De fait, ce travail introspectif et collectif a fait émerger des implicites fondamentaux spécifiques ou communs à ces disciplines dont les enseignants n’avaient pas conscience ; qu’ils n’avaient jamais partagé avec leurs élèves ; et qu’ils ont identifié comme la source de difficultés jusque-là inexprimables rencontrées par nombre d’entre eux. L’hypothèse défendue ici est donc que — par effet d’analogies et de contrastes — le dialogue interdisciplinaire peut être un formidable outil de renforcement et de clarification de l’enseignement disciplinaire, qui pourrait jouer un rôle clé dans la formation des enseignants.

International audience

International audience; Hydroxide exchange membrane fuel cells (AEMFC) are clean energy conversion devices that are an attractive alternative to the more common proton exchange membrane fuel cells (PEMFCs), because they present, among others, the advantage of not using noble metals like platinum as catalysts for the oxygen reduction reaction. The interest in this technology has increased exponentially over the recent years. Unfortunately, the low durability of anion exchange membranes (AEM) in basic conditions limits their use on a large scale. We present in this review composite AEM with one-dimensional, two-dimensional and three-dimensional fillers, an approach commonly used to enhance the fuel cell performance and stability. The most important filler types, which are discussed in this review, are carbon and titanate nanotubes, graphene and graphene oxide, layered double hydroxides, silica and zirconia nanoparticles. The functionalization of the fillers is the most important key to successful property improvement. The recent progress of mechanical properties, ionic conductivity and FC performances of composite AEM is critically reviewed

La relation sciences et art au sein de la Licence Sciences et humanités La chimie est un cas à part parmi les sciences : elle s’est construite au moins autant par la pratique que par la connaissance théorique. Les Égyptiens savaient non seulement préparer le pigment bleu, connu sous le nom de bleu égyptien, mais ils savaient aussi fabriquer l’antimoniate de plomb de couleur jaune, le blanc de plomb et le minium de couleur rouge. Ce savoir-faire révèle l’Égypte ancienne comme une civilisation ...

International audience; A pH-responsive drug delivery system composed of N-(propyl)aniline (N-ANI) modified mesoporous silica nanoparticles as a carrier, and β-cyclodextrin (β-CD) as a cap was prepared and investigated. The system was studied for co-adsorption and co-delivery of two different drugs; an anticancer drug 5-fluorouracil (5-FU), and anti-inflammatory agent naproxen (NAP). Detailed adsorption study of the drugs themselves as well as in their mutual mixture was performed. The drug release experiments were realized in simulated body fluid (pH = 7.4) and slightly acidic medium (pH = 5) imitating the pH of tumor affected area. The experiments showed, that at physiological pH 7.4, the prepared drug delivery system released no drug, at slightly acidic medium (pH = 5) the β-CD caps were loosened, and drugs were released (88.5% and 98.7% for 5-FU and NAP, respectively). To investigate the efficiency of the designed system for the delivery in biological environment, the biocompatibility and cytotoxicity experiments were performed using U87 MG and SKBR3 cancer cells by fluorescence microscopy, flow-cytometry, MTT. apoptotic and CAM assays.

International audience; The present study reports a synthetic condensation process of a vegetable oil (waste) reacted with triethanolamine, maleic anhydride and acrylonitrile in (1 : 1.2 : 2 : 1) mole ratios to obtain N-(β-ethoxypropionitrile)-N,N-bis(2-hydroxyethylethoxy) fatty amide as a major inhibitory product. Corrosion property of steel in a 3% NaCl solution in the presence of a potential inhibitor was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. These methods gave consistent results, from which it is noticeable that inhibition efficiency increases with the increasing concentration of the inhibitor. Gravimetric studies show an increase in the sample mass at an inhibitor concentration of 10 mM, indicative of adsorbed film formation on the surface. The polarization curve results showed that the compound demonstrates itself as an anodic-type inhibitor. A rise in polarization resistance values in the EIS measurements also confirmed that the compound acts as an effective inhibitor of steel corrosion. Furthermore, the R(CR)(QR) equivalent circuit was used to interpret the results obtained in the investigation of the corrosion behaviour of steel in solution with an inhibitor. The standard adsorption free energies calculated from the Langmuir isotherm indicate that adsorption takes place by physical and chemical mechanisms. The presence of adsorbed protective film was confirmed by FT-IR spectrum and SEM micrographs.

International audience; Nanoporous carbons remain the most promising candidates for effective hydrogen storage by physisorption in currently foreseen hydrogen-based scenarios of the world’s energy future. An optimal sorbent meeting the current technological requirement has not been developed yet. Here we first review the storage limitations of currently available nanoporous carbons, then we discuss possible ways to improve their storage performance. We focus on two fundamental parameters determining the storage (the surface accessible for adsorption and hydrogen adsorption energy). We define numerically the values nanoporous carbons have to show to satisfy mobile application requirements at pressures lower than 120 bar. Possible necessary modifications of the topology and chemical compositions of carbon nanostructures are proposed and discussed. We indicate that pore wall fragmentation (nano-size graphene scaffolds) is a partial solution only, and chemical modifications of the carbon pore walls are required. The positive effects (and their limits) of the carbon substitutions by B and Be atoms are described. The experimental ‘proof of concept’ of the proposed strategies is also presented. We show that boron substituted nanoporous carbons prepared by a simple arc-discharge technique show a hydrogen adsorption energy twice as high as their pure carbon analogs. These preliminary results justify the continuation of the joint experimental and numerical research effort in this field.

The scientific literature is replete with data describing novel porous structures, making the selection of an adsorbent for storage and separation applications a difficult task, and often leading t...

International audience; elf-standing binderless FAU-X monoliths with hierarchical trimodal porosity have been synthesized for the first time by a double pseudomorphic transformation. Parent silica monoliths obtained by the combination of spinodal decomposition and sol-gel process have first been synthesized. The silica monoliths have been then transformed into silica-alumina monoliths (0.25

The majority of research into metal-organic frameworks (MOFs) focuses on their crystalline nature. Recent research has revealed solid-liquid transitions within the family, which we use here to create a class of functional, stable and porous composite materials. Described herein is the design, synthesis, and characterisation of MOF crystal-glass composites, formed by dispersing crystalline MOFs within a MOF-glass matrix. The coordinative bonding and chemical structure of a MIL-53 crystalline phase are preserved within the ZIF-62 glass matrix. Whilst separated phases, the interfacial interactions between the closely contacted microdomains improve the mechanical properties of the composite glass. More significantly, the high temperature open pore phase of MIL-53, which spontaneously transforms to a narrow pore upon cooling in the presence of water, is stabilised at room temperature in the crystal-glass composite. This leads to a significant improvement of CO2 adsorption capacity., The formation of composite materials has been widely exploited to alter the chemical and physical properties of their components. Here the authors form metal–organic framework (MOF) crystal–glass composites in which a MOF glass matrix stabilises the open pore structure of MIL-53, leading to enhanced CO2 adsorption.

International audience; Black finished surfaces have extensive applications in many domains, such as optics, solar cells, and aerospace. The single step electrodeposition of superhydrophobic black NiO films from a dimethyl sulfoxide based electrolyte is described in this paper. The physicochemical properties of the obtained film were characterized using Scanning Electron Microscopy, X-ray Diffraction, and electrochemical tests (Electrochemical Impedance Spectroscopy and potentiodynamic polarization). A rough surface with a low reflection of light was formed after the deposition process that increased the contact angle of water from about 87º (for bare Cu) to 163º (in presence of the black coating), which improved the corrosion resistance of the Cu substrate by about 30%. The formed black NiO film revealed a notably high stability and kept its appearance even after corrosion tests.

International audience; Mesoporous silica materials were investigated as the carriers for pH-sensitive drug delivery systems. Porous silica SBA-15 was first functionalized by anchoring N-[3-(trimethoxysilyl) propyl] aniline groups on the surface. After loading of an antineoplastic agent 5-fluorouracil, the pores were capped by β-cyclodextrin molecules. The studied samples were characterized by N 2 adsorption/desorption measurements, thermal analysis, powder X-Ray Diffraction, and Transmission Electron Microscopy. Adsorption properties of 5-fluorouracil were explored via the construction of adsorption isotherms. The amount of 5-FU adsorbed on amine-functionalized SBA-15 was 60 mg per 1 g of solid. The adsorption of 5-fluorouracil on silica was also monitored by microcalorimetry, showing low adsorption enthalpies. Drug release properties from matrices were studied using UV-Visible spectroscopy with the un-blocked and blocked pores configuration to demonstrate the efficiency of the pH-responsive nanovalves and evaluated using different kinetic models. It was shown that no drug release occurred at neutral pH and that more than 80% of drug adsorbed amount was released at pH = 5. Working at the equilibrium, the initial burst of the drug from the silica surface, usually observed in other porous silica drug delivery systems, was avoided. The interaction between the β-cyclodextrin molecules and grafted amine functions were also studied as a function of pH. Finally, the cytotoxicity tests were performed using human glioma U87 MG cells.

Owing to their low lattice thermal conductivity, many compounds of the n(PbTe)-m(Bi2Te3) homologous series have been reported in the literature with thermoelectric (TE) properties that still need improvement. For this purpose, in this work, we have implemented the band engineering approach by applying biaxial tensile and compressive strains using the density functional theory (DFT) on various compounds of this series, namely Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5. All the fully relaxed Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5 compounds are narrow band-gap semiconductors. When applying strains, a semiconductor-to-metal transition occurs for all the compounds. Within the range of open-gap, the electrical conductivity decreases as the compressive strain increases. We also found that compressive strains cause larger Seebeck coefficients than tensile ones, with the maximum Seebeck coefficient being located at −2%, −6%, −3% and 0% strain for p-type Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5, respectively. The use of the quantum theory of atoms in molecules (QTAIM) as a complementary tool has shown that the van der Waals interactions located between the structure slabs evolve with strains as well as the topological properties of Bi2Te3 and PbBi2Te4. This study shows that the TE performance of the n(PbTe)-m(Bi2Te3) compounds is modified under strains.

International audience; In the endless possibility space of metal organic framework design, the quest for new multifunctional materials with desirable properties is still ongoing. At the environmental level, their development poses a promising industrial alternative for the management of aqueous pollutants and for storage and separation of gases. In this context, the recently reported porphyrinic framework 1, [Ni5(H2TCPP)2O(H2O)4]•nS (where H6TCPP is meso-tetra(4-carboxyphenyl)porphyrin and S is the solvent) is investigated through a fundamental study of its thermal and magnetic properties, together with its potential as an adsorbent for pollutants in the liquid and gas phase. Sorption of four organic dye solutions with different chemical features was carried out, with good affinity found towards small cationic species. In addition, a series of different gases (N2, O2, CO, CO2, C1-C4 hydrocarbons) were tested through the use of adsorption microcalorimetry in order to understand the interactions and selectivity of 1. This study affords an in-depth approach to the characterization of a new selective adsorbent for pollutants of industrial interest.