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Designing and manufacturing multifunctional nanoparticles (NPs) are of considerable interest for both academic and industrial research. Among NPs used in this field, iron oxide NPs show low toxicity compared to metallic ones and are thus of high interest for biomedical applications. In this work, superparamagnetic Fe3−δO4-based core/shell NPs were successfully prepared and characterized by the combination of different techniques, and their physical properties were investigated. We demonstrate the efficiency of the layer-by-layer process to graft polyelectrolytes on the surface of iron oxide NPs. The influence of the polyelectrolyte chain configuration on the magnetic properties of the Fe3−δO4/polymer core/shell NPs was enlightened. The simple and fast process described in this work is efficient for the grafting of polyelectrolytes from surfaces, and thus, derived Fe3−δO4 NPs display both the physical properties of the core and of the macromolecular shell. Finally, the cytotoxicity toward the human THP-1 monocytic cell line of the core/shell NPs was assessed. The results showed that the polymer-capped Fe3−δO4 NPs exhibited almost no toxicity after 24 h of exposure at concentrations up to 25 μg mL–1. Our results show that these smart superparamagnetic nanocarriers with stealth properties are promising for applications in multimodal cancer therapy, including drug delivery.

7 Figuras, 2 Tablas, Mesoporous carbons containing up to 3.6 at.% N and 4.4 at.% O and exhibiting graphitic character have been prepared from Ni(II) and Fe(II) phthalocyanines by direct pyrolysis or by HTC + pyrolysis, and subsequently applied as supercapacitor materials. No mesoporous templates or doping post-treatments were used, and the catalytic effect of Ni(II) and Fe(II), naturally present in the precursor molecules, allowed obtaining graphitic carbons at temperatures ≤ 900 °C. Metals were encapsulated in the core of onion–like structures with no contact with the electrolyte, so that electrodes were prevented from degradation during device operation. The materials exhibited high rate capabilities up to 1 V s−1, higher interfacial capacitances than a wide variety of materials possessing higher surface areas, and high capacitance retentions up to 99% at 5 A g−1 current density throughout 10 000 charge–discharge cycles. The electrochemical performances of the phthalocyanine-derived carbons are due to their graphitic character and to the pseudocapacitance contribution of the surface groups through Faradaic reactions. This work opens a new way to obtain carbon materials from a great family of metal phthalocyanines, since the central metal and the radicals of the latter can be varied to tune the carbon properties for specific applications., The IJL research team gratefully acknowledges the Dr. Marta Sevilla’s departement for its scientific support, and the financial support of the CPER 2007-2013 “Structuration du Pôle de Compétitivité Fibres Grand’Est” (Competitiveness Fibre Cluster), through local (Conseil Général des Vosges), regional (Région Lorraine), national (DRRT and FNADT) and European (FEDER) funds. Dr. A. Sanchez-Sanchez acknowledges the CNRS for financing her post-Doctoral contract.

Textile wastewater containing toxic dyes needs efficient treatment before being released into the environment. Certain dyes are known or presumed to have carcinogenic potential for humans. In this work, hybrid electrochemical processes including electrocoagulation (EC) alone and combined with electro Fenton (EF), anodic oxidation (AO) and peroxi-coagulation (PC) were tested to treat real textile wastewater using a batch reactor. A sequential EC and EF (EC-EF) process was found to be more effective. The experimental results indicated that the effectiveness of the treatment decreases in the following order: EC-EF > EC-AO > EC-PC > EC. EC-EF results showed a decrease in chemical oxygen demand (COD, 97%), total organic carbon (98%), total suspended solids (98%), and the concentration of metal species; showing that the treatment of such wastewater type can be achieved by combined EC-EF process in a one-pot bench-scale reactor. The electrical energy consumption, the iron dissolution, and the biological oxygen demand/COD ratios of EC and EC-EF processes were evaluated. Characterization of the sludge generated during EC treatment at current density of 20 mA cm− 2 was carried out. Precipitation, adsorption, and electrochemical oxidation/reduction of organic dyes and metallic ions occurred during the treatment. This investigation shows the efficiency of combined EC-EF to treat textile wastewater.

The preparation of well-defined organo-mineral assemblies under controlled conditions is required to improve our understanding of the formation and surface reactivity of micrometric aggregates, ubiquitous in soils and continental aquatic media. We aim at investigating the building of organo-mineral assemblies with a specific focus on the assembly mode and its consequence on the final properties of the micrometric aggregates. In this work, the preparation and detailed characterization of clay-size aggregates composed of a clay mineral (illite), organic polymer (Dextran polysaccharide) and iron (hydr)oxide are reported, with a focus on the structural organization of the generated aggregates. A step-by-step strategy was developed, and three sets of clay-size composites were prepared with illite particles as a starting material. In two first steps, two distinct sets of two-component composites were obtained according to different procedures. Illite‑iron (hydr)oxide composites were obtained by alkaline hydrolysis of iron in the presence of illite particles, and illite-Dextran aggregates were obtained through the addition of Dextran polysaccharide to an illite suspension. In a third step, three-component micro-aggregates were obtained by subsequent addition of Dextran to suspensions containing the formed illite‑iron (hydr)oxide composite. The so-prepared 2- and 3- component aggregates were investigated by electrophoresis, electron microscopy, X-ray absorption and FTIR spectroscopies. For materials containing Dextran, electrophoretic mobility measurements evidenced variations of surface charge, combined with an increase of aggregate size highlighted by dynamic light scattering. Electron microscopy and EXAFS at iron K-edge evidenced the precipitation of nanoparticles of iron (hydr)oxide onto clay mineral surfaces. FTIR data in transmission and diffuse reflectance modes supported not only the adsorption of Dextran but also the preferential localization of Dextran at the external surfaces of the aggregates. All in all, data collected on the two- and three-component materials demonstrated that the presence of iron (hydr)oxide nanoparticles on the surface of illite strongly modified the organization of organic and mineral constituents.

A new ternary phase with a composition Al1+xV2Sn2–x (x = 0.19) has been found during investigation of the Al–V–Sn ternary system. Single-crystal X-ray diffraction measurements reveal that this ternary phase crystallizes with an orthorhombic structure with a = 5.5931(1) A, b = 18.8017(5) A, and c = 6.7005(2) A (space group Cmce). This compound is thus isostructural to the GaV2Sn2 structure type, showing a layered structure composed of vanadium cluster bands formed with pentagonal faces intercalated by Sn atom layers. High-resolution transmission electron microscopy measurements confirm the orthorhombic structure. Regarding lattice perfection, no dislocation could be identified within the probed Al1.19V2Sn1.81 single-crystal lamella. Ab initio calculations reveal a reduction of the density of states at the Fermi level, which could be attributed to both a Hume–Rothery effect combined with strong spd hybridization.

Present study focuses on crystal violet adsorption by mineral halloysite and synthetic pecoraite nanoscrolls. Being scrolled in opposite directions, these two materials serve both as good adsorbents and model objects to understand the dye adsorption mechanism. Heat treatment of the nanoscrolls allowed us to track the adsorption process features by changing the structure and surface state of the particles. Structural transitions were observed by complementary techniques including X-ray diffraction, thermal analysis, electron microscopy, N2 adsorption and ς-potential measurements. By a fast UV/VIS study of adsorption kinetics, it became possible to take a closer look at the very initial steps of the process. Intraparticle diffusion governs the overall adsorption kinetics of the dye by halloysite and pecoraite nanoscrolls. The presence of OH-groups on the nanoscrolls' surface strongly facilitates the initial stage of adsorption. Structural transition at around 600 °C increases adsorption rate and performance of synthetic pecoraite due to ς-potential sign change.

Nanosecond-pulsed spark discharge between two lead electrodes in liquid nitrogen has been used to synthesize hexagonal lead nanosheets. These original nanostructures are collected on a substrate located under the electrodes. After the full evaporation of the liquid nitrogen, the nanosheets are oxidized in air and transform into a lead dioxide. The resulting hexagonal sheets have typical widths of around 1 µm and typical thicknesses of around 10 nm. Investigations by energy dispersive spectroscopy microanalysis, transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy and electron microdiffraction were performed in order to identify the crystal structure in which these hexagonal nanosheets crystallize. An analysis of the chemical composition pointed to a stoichiometric lead dioxide, PbO2. This PbO2lead dioxide crystallizes in the hexagonal system (a= 0.912 nm andc= 1.265 nm) and belongs to the space groupP6/m2/m2/m. On the basis of group theory (symmetry analysis), the nanosheets develop a hexagonal-prismatic shape in liquid nitrogen, assumed to be an isotropic medium. From the energetic point of view, this shape, dictated by the 6/m2/m2/mpoint group, corresponds to an absolute extremum, an indicator of the stability of this lead dioxide. A mechanism similar to that of the ledge mechanism explaining the formation of thin plates in a metallic matrix has been adapted and proposed for the formation of the lead nanosheets in the liquid nitrogen. When the liquid nitrogen is removed, the lead nanosheet is oxidized, leading to a lead dioxide, inheriting the nanosheet morphology. As far as the authors are aware, this is the first time that such a lead dioxide has been synthesized by spark discharge in liquid nitrogen followed by oxidation in air. The crystallographic structure is determined and the morphology is explained. A mechanism for the development of the lead nanosheets and their oxidation is proposed. This hexagonal phase, designated γ-PbO2, is thought to be the third polymorph after the α-PbO2and β-PbO2phases of lead dioxide, the former being orthorhombic and the latter being tetragonal.

Batteryless, wireless, and packageless acoustic wave sensors are particularly desirable for harsh high-temperature environments. In this letter, an acoustic wave sensor based on a lithium niobate (Y + 128° cut, abbreviated LN-Y128) substrate with a buried platinum interdigital transducer (IDT) in an aluminum nitride (AlN) overlayer is investigated. Previously, it was demonstrated theoretically that due to the specific properties of LN-Y128, Rayleigh-type guided waves can propagate at the AlN/IDT(Pt)/LN-Y128 interface. Here, this structure is, for the first time, studied experimentally, including the growth and properties of the AlN layer onto irregular platinum IDTs. Both Shear Horizontal and Rayleigh-type waves have been identified after the AlN deposition and the velocities are consistent with the fitted SDA-FEM-SDA (a combination of finite element modeling with spectral domain analysis) simulations. Electrical measurements with a surface perturbation and temperature measurements show that the AlN/IDT(Pt)/LN-Y128 bilayer structure is promising as a packageless high-temperature sensor.

In Agadir, a water-scarce Moroccan region, municipal and industrial wastewater is tertiary-treated to be reused in golf courses. Wastewater reuse has been constrained by severe clogging of emitters, which caused technical and financial problems. This study aimed to perform an in-depth characterization of the treated wastewater (TWW) in relation to its susceptibility to cause clogging, and to assess the capacity of an aeration post-treatment to reduce the clogging potential. The post-treatment consisted of injecting different airflows (0–33 L/(h Lreactor) into the TWW. The structural, morphological and elemental composition of the clogging matter collected in the irrigation pipeline was characterized using scanning electron microscopy, scanning transmission electron microscopy, X-ray diffraction and X-ray energy dispersive spectroscopy. The 15-day aeration post-treatment at 16.5 L/(h Lreactor) presented the best cost–benefit ratio. Organic matter was totally degraded. Calcium was reduced by 9%, bicarbonates by 54%. The analysis of the deposits induced by the aeration post-treatment revealed a relevant decrease of the major constituents of the clogging deposits found in the irrigation pipeline. The results show the effectiveness of post-aeration in biodegrading residual organic matter and precipitating several salts, thus reducing the clogging potential.

peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 05/11/2021 Here we report on the thermal properties of Mg−Ni‐phyllosilicate nanoscrolls as a promising precursor for production of Ni/silicate composite catalysts. Spontaneous scrolling of the phyllosilicate layer originating from size difference between metal‐oxygen and silica sheets provides high surface area of the catalyst. Metal nanoparticles can be obtained directly from the matrix by H2 reduction. The phyllosilicate structure passed through a number of transformations including partial dehydroxylation with formation of sepiolite‐like phase followed by silicate or oxide crystallization. Temperature ranges of these transitions overlapped with the reduction process sophisticating the H2 consumption profiles. In particular, some amount of Ni2+ got sealed up by the sepiolite structural features, that opened a path for the tuning of Ni0 : Ni2+ ratio of the catalyst. An increase of Ni content in the system yielded a decrease in the metal nanoparticles sizes due to both high intensity of nucleation and type of residual matrix. Ni nanoparticles size distribution and specific surface area of the composite catalysts governed conversion rate of hexene‐1 and acetone hydrogenation. In the view of the turnover frequency MgNi2Si2O5(OH)4 precursors were slightly more preferable than pure Ni3Si2O5(OH)4.

International audience; An Al-Zr (4 at.% Zr) film is deposited on High Speed Steel substrates by pulsed Direct Current magnetron sputtering in order to provide sacrificial corrosion resistance of steel. A TiO2 layer is synthesized on the top by aerosol-assisted metal-organic chemical Vapour Deposition (AA-MOCVD) in order to insure anti-biofouling behaviour. TiO2 coating has a typical CVD microstructure and the film is anatase single phased. The as-deposited Al-Zr film is an extended supersaturated solid solution Al(Zr) of Zr in Al. The AA-MOCVD process is performed at 773 K for 40 min. This annealing leads to a fine precipitation of highly coherent metastable Al3Zr(L12) phase in the Al(Zr) matrix. Larger precipitates with a needle like morphology, which crystallize in the equilibrium tetragonal Al3Zr(D023) phase are also observed. Transmission electron microscopy analysis clearly shows the cube on cube orientation between Al3Zr(L12) phase and Al(Zr) matrix. As the cubic Al3Zr(L12) metastable phase is beneficial for the mechanical properties of bulk aluminium based alloys, this result opens the investigation field on Al-Zr coatings, which can provide sacrificial protection of steels.

To clarify the influence of manganese on the oxidation behavior of Ni–Cr alloys, high resolution transmission electron microscopy was used to examine the microstructure and chemistry of oxide scales forming at 1050 °C on Ni–25Cr–xMn (x = 0.5, 1 and 1.5% wt) in 200 Pa O2. The scales consisted of two layers of chromia and one layer of spinel Mn1+xCr2-xO4. The internal layer exhibited an equiaxed grain structure, whereas columnar grains developed in the outer layer. The results demonstrated that the spinel composition at the chromia-spinel interface was similar regardless of the manganese concentration.

Ta, Hf, TaCx, HfCx, and TaxHf1-xCy coatings were deposited by reactive pulsed Direct Current (DC) magnetron sputtering of Ta or Hf pure metallic targets in Ar plus CH4 gas mixtures. The properties have been investigated as a function of the carbon content, which is tuned via the CH4 flow rate. The discharge was characterized by means of Optical Emission Spectroscopy and, in our conditions, both Ta-C and Hf-C systems seem to be weakly reactive. The structure of the as-deposited pure tantalum film is metastable tetragonal &beta, Ta. The fcc-MeCx carbide phases (Me = Ta or Hf) are {111} textured at low carbon concentrations and then lose their preferred orientation for higher carbon concentrations. Transmission Electron Microscopy (TEM) analysis has highlighted the presence of an amorphous phase at higher carbon concentrations. When the carbon content increases, the coating&rsquo, s morphology is first compact-columnar and becomes glassy because of the nano-sized grains and then returns to an open columnar morphology for the higher carbon concentrations. The hardness and Young&rsquo, s modulus of TaCx coatings reach 36 and 405 GPa, respectively. For HfCx coatings, these values are 29 and 318 GPa. The MeCx coating residual stresses increase with the addition of carbon (from one-hundredth of 1 MPa to 1.5 GPa approximately). Nevertheless, the columnar morphology at a high carbon content allows the residual stresses to decrease. Concerning TaxHf1-xCy coatings, the structure and the microstructure analyses have revealed the creation of a nanostructured coating, with the formation of an fcc superlattice. The hardness is relatively constant independently of the chemical composition (22 GPa). The residual stress was strongly reduced compared to that of binary carbides coatings, due to the rotation of substrates.

Functionalized multi-walled carbon nanotubes (MWCNT) have become the focus of increased research interest, particularly in their application as tools in different areas, such as the biomedical field. Despite the benefits associated with functionalization of MWCNT, particularly in overcoming issues relating to solubility, several studies have demonstrated that these functionalized nanoparticles display different toxicity profiles. For this study, we aim to compare NR8383 cells responses to three well-characterized MWCNT with varying functional groups. This study employed cytotoxicity assays, transcriptomics and proteomics to assess their toxicity using NR8383 rat alveolar macrophages as an in vitro model. The study findings indicated that all MWCNT altered ribosomal protein translation, cytoskeleton arrangement and induced pro-inflammatory response. Only functionalized MWCNT alter mTOR signaling pathway in conjunction with increased Lamtor gene expression. Furthermore, the type of functionalization was also important, with cationic MWCNT activating the transcription factor EB and inducing autophagy while the anionic MWCNT altering eukaryotic translation initiation factor 4 (EIF4) and phosphoprotein 70 ribosomal protein S6 kinase (p70S6K) signaling pathway as well as upregulation Tlr2 gene expression. This study proposes that MWCNT toxicity mechanisms are functionalization dependent and provides evidence that inflammatory response is a key event of carbon nanotubes toxicity.

Plasmonic nanosponges are a powerful platform for various nanophotonic applications owing to extremely high local field enhancement in metallic nanopores. The filling of the nanopores with high-refractive index semiconductors (e.g. Si, Ge, GaP, etc.) opens up opportunities for the enhancement of nonlinear effects in these materials. However, this task remains challenging due to the lack of knowledge on the integration process of metal and high-index semiconductor components in such nanoobjects. Here, we investigate metal-dielectric nanoparticles fabricated from bilayer Si/Au films by the laser printing technique via a combination of theoretical and experimental methods. We reveal that these hybrid nanoparticles represent the Au sponge-like nanostructure filled with Si nanocrystallites. We also demonstrate that the Au net provides strong near-field enhancement in the Si grains increasing the white light photoluminescence in the hybrid nanostructures compared to uniform Si nanoparticles. These results pave the way for engineering the internal structure of the sponge-like hybrid nanoparticles possessing white light luminescence and control of their optical properties on demand.

International audience; Candida antarctica B lipase (CAL-B) was immobilized on purified and functionalized multiwalled carbon nanotubes (MWCNTs). Both immobilization routes, physical adsorption and covalent bonding, were investigated. MWCNT functionalization by a non-aggressive oxidation by potassium permanganate led to an interesting balance between the hydrophilic and the hydrophobic areas of the MWCNT surface; the former being responsible of the good dispersion of MWCNTs in water and the latter having a favorable affinity with CAL-B. The enzyme loadings reached were significant: around 16 wt. % and 21 wt.% for non-covalent and covalent immobilization, respectively. The enzymatic activity was studied with the reaction of O-acylation of geraniol into geranyl acetate by CAL-B in supercritical CO2. Even if a decay in synthesis of geranyl acetate was observed over cycling for both CAL-B@MWCNT catalysts, it was demonstrated that the regioselectivity of CAL-B was unchanged through immobilization on the MWCNT surface for both routes. Interestingly, it was shown that a fully green enzymatic process can be achieved with these prepared CAL-B@MWCNT biocatalyst. Such approach could be transferred to other support/enzyme systems for developing new eco-friendly synthesis processes.

International audience; We report in this study the experimental investigation of the dynamic viscosity of purified multi-walled carbon nanotubes (MWCNT) water and water-propylene glycol-based nanofluids in the temperature range 10-80 degrees C. Four weight concentrations of MWCNTs are considered, between 0.005 and 0.1 wt.%. Triton X-100, a common nonionic surfactant, is used to disperse the nanotubes and stabilize the nanofluids as evidenced by optical characterization. Purified and non-damaged MWCNTs are used for nanofluid preparation by the two-step method. MWCNT characterization is deeply investigated from a set of complementary techniques such as thermogravimetric analysis, transmission electron microscopy, and Raman spectroscopy. The studied nanofluids behave as Newtonian fluids for low nanotube content while a shear-thinning behavior is noticed for higher concentration. Finally, the viscosity enhancement of nanofluids with MWCNT loading is compared to the modified Maron-Pierce model considering the presence of aggregates and their size obtained from optical observations.

International audience; Because the binary chalcogenide SnTe is an interesting Pb-free alternative to the state-of-the-art thermoelectric material PbTe, significant efforts were devoted to the optimization of its thermoelectric properties over the last few years. Here, we show that saturation-annealing treatments performed at 823, 873 or 973 K under Sn-rich conditions provide a successful strategy to prepare polycrystalline samples with a controlled concentration of Sn vacancies. Both scanning transmission electron microscopy and Mössbauer spectroscopy demonstrate the absence of Sn-rich areas at the grain boundaries in the saturation-annealed samples. Transport property measurements, performed over a wide range of temperatures (5-800 K), show that this technique enables achieving thermoelectric performances at 800 K similar to those obtained using Sn self-compensation. The three saturation annealing temperatures result in comparable transport properties across the entire temperature range due to similar hole concentrations ranging between 1.0 and 1.5 Â 10 20 cm À3 at 300 K. As equally observed in samples prepared by other synthetic routes, the temperature dependence of the Hall mobility evidences that charge transport is strongly affected by point-defect scattering caused by the random distribution of Sn vacancies.

International audience; The interface between pioneer sessile bacteria and a supporting substrate can be probed in situ and at the molecular scale by infrared spectroscopy in the attenuated total reflection mode (ATR‐FTIR). Here, a self‐assembled monolayer (SAM) of amino‐terminated alkanethiol is formed on the internal reflection element (IRE) composed of zinc selenide, and the attachment of model bacterium Lactobacillus rhamnosus GG (LGG) is subsequently studied. The impact of the beforehand surface preparation of the IRE on the SAM is studied on ZnSe substrates (i) cleaned by exposure to ozone/UV, (ii) acid cleaned, or (iii) coated with a thin gold film. The surface properties of the obtained substrates are analyzed by atomic force and electron microscopies, and elastic ion backscattering spectrometry. The kinetics of the formation and the organization of the formed SAMs are strongly surface dependent, as evidenced with ATR‐FTIR. Acid‐cleaned and gold‐coated IREs are the least and most favorable substrates for alkanethiol SAM formation, respectively. Regardless of differences in SAM properties, the average degree of LGG attachment is similar on all functionalized substrates. The molecular organization of LGG cells, however, is substrate‐dependent suggesting a possible effect of SAM organization on the bacteria–substrate interface.

A simple method to synthesise hexagonal lead sheets, which belong to the class of two-dimensional materials, is proposed. These objects are collected on a substrate located under two lead electrodes, between which nanosecond-pulsed spark discharges are ignited in liquid nitrogen. The hexagonal sheets are single crystals produced by gas phase condensation. Once nitrogen completely evaporates, the sheets change to PbO2 by oxidation in air. The oxidation process induces stress that pleats the uppermost sheets or open cracks at the centre. The thickness of the individual objects typically varies from 4 to 20 nm. When the number of discharges is more than about 2000, in addition to sheets, two types of PbO2 sticks start to form: bundles composed of nanosticks (length 5 μm and diameter 50 nm) and isolated sticks (length 20 μm and diameter 500 nm). These new nanostructures mainly form because of the way the discharge erodes the lead electrodes. Initially, anisotropic erosion driven by the orientation of the crystallographic planes of the lead crystals produces octahedra and nanosticks, and the nanosticks grow on the electrode surfaces as discharge proceeds. After about 2000 discharges, the nanosticks are sufficiently long that they can be easily broken, probably by mechanical stress, and they fall onto the underlying substrate.

Zinc tin nitride (ZnSnN2) thin films have been deposited on glass and silicon substrates using a reactive co-sputtering process. Although the deposition temperature was limited to the room temperature, the films show a highly crystallization level and a strong preferred orientation in the [001] direction. The film composition, measured using energy dispersive X-ray spectroscopy and electron probe microanalysis, indicates a possible tin understoichiometry (or a zinc and a nitrogen overstoichiometry). As confirmed by transmission electron microscopy, the main oxygen contamination of the films results from oxidation of the grains boundaries after air exposure of the samples. X-ray photoelectron spectroscopy and Mossbauer spectrometry have been used to determine the chemical environment of atoms in the ZnSnN2 crystals. Both methods confirm that Sn4+ ions are bonded to nitrogen atoms and that the oxygen contamination results in the formation of Sn2+ ions. Zinc tin nitride exhibit an electron mobility at room temperature close to 3.8 cm2 V−1 s−1 and an optical band gap of 1.8 eV as measured independently from UV–visible spectrometry and ellipsometry. The results obtained in the present study confirm the suitability of ZnSnN2 thin films as an Earth abundant material for absorber layer in photovoltaic devices.

International audience; Nanofluids which consist of the addition of nanoparticles in a base fluid are envisaged for a large domain of applications. For many of them, the surface tension (ST) behavior of the prepared nanofluids is a key parameter to exploit their thermophysical properties. Due to their remarkable properties, carbon nanotubes (CNTs) are commonly used to develop nanofluids. However, the evolution of the ST of CNT-based nanofluids is still far from being understood and predictable. In the present work, two base fluids were used: water and a commercial mixture of propylene-glycol/water (around 40:60 wt%). The impact of the used multi-walled CNT (MWCNT) addition, MWCNT concentration (0.001 and 0.1 wt%) and temperature variation (273.15–333.15 K) on the density and ST evolution for the two kinds of CNT-based nanofluids is studied. The chemically modified MWCNTs are assumed to bear both localized hydrophilic areas due to grafted functional groups and remaining hydrophobic surfaces. The found difference in ST behavior between the two types of nanofluids is explained in light with the involved interfaces in each nanofluid. ST evolution is found to strongly depend on the CNT surface properties.

In this study we report the microstructure and the thermoelectric properties of p-type Bi-Sb-Te 60 nm nanowires using ion track-etched polycarbonate templates for fixed applied potentials. A mixture of Bi+III, Sb+III and Te+IV in specific tartaric-nitric acid electrolyte was prepared in order to obtain the Bi0.5Sb1.5Te3 compound. Cathodic linear sweep voltammograms revealed the Te deposition followed by the deposition of Bi-Sb-Te compounds at more negative potentials with defined compositions. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) characterizations show polycrystalline and smooth nanowires of 60 nm diameter regardless of the deposition potential. At −0.1 V potential, the nanowires exhibit a chemical content i.e. Bi0.4Sb1.3Te3.3 close to the targeted composition. According to HR-TEM analysis, large grains with preferential orientation in [015]* containing twin boundaries were observed. The Te excess can be explained by the presence of over inserted Te atoms into the quintuplet interstices. The nanostructures exhibit semiconducting behavior with positive Seebeck coefficient (+138 μV/K) associated with electrical resistivity (128 μΩ m). Comparative electrical measurements between individual nanowires and bundle of nanowires show that the overall electrical resistance of the membrane/nanowires composite is governed by internal resistance rather than material one.

The peculiar behaviour of zinc depending on whether it is used pure or alloyed in Cu63Zn37 wire electrodes leads either to nanosheets or to nanoparticles when it is processed by nanosecond pulsed discharges in liquid nitrogen. Using one electrode of copper and one electrode of zinc gives core-shell Cu@Zn nanoparticles but no alloy for the smallest nanoparticles (typically below 20 nm). Once nitrogen is evaporated, their oxidization in air produces Cu2O@ZnO nanoparticles. If both electrodes are made of Cu63Zn37, then the smallest nanoparticles are made of Cu and Zn and oxidized next in air to give Cu2O and ZnO nanoparticles. No alloy is formed either. Time-resolved optical emission spectroscopy gives clues on the origin of such behaviours, explaining why no alloy is formed when electrodes are made of different materials.

A direct band gap of 1.6 eV has been identified in wurtzite CoO thin films, which matches the required value to achieve a theoretically high conversion efficiency solar cell. Its p-type conduction has been determined and an intense sub-gap absorption between 0.7 and 1.1 eV has been observed.

Te-Bi core-shell nanowires were synthesized by electrochemical deposition in ionic liquids without using a template. The nanowires were synthesized in two steps: self-standing single crystal Te nanowires with a diameter of 76.2±28.4nm and a length of a few microns were electrodeposited first, taking advantage of the templating properties of the mixture of ionic liquids EOPipTFSI:EOPipBr 95:5 mole%. The Bi shell was then deposited on the Te core in EOPipTFSI. The influence of various experimental parameters on Bi shell deposition was studied. Thanks to the higher viscosity of the electrolyte compared to an aqueous medium, a lower growth rate is observed, leading to a thin layer of bismuth. In addition, High Resolution Transmission Electronic Microscopy shows that under optimal conditions the Te nanowires are entirely covered by a homogeneous, compact and polycrystalline Bi shell and that the core/shell interface is smooth. Keywords: Core-shell nanowires, Ionic liquid, Electrodeposition, Bismuth, Tellurium

Increased interconnection between carbon nanofiller and ceramic support can give enhanced thermal conduction of a phase change material in thermal energy storage application. In the present work, we demonstrate a new strategy by directly growing the carbon nanofiller (i.e. graphene) on the surface of MgO ceramic via a chemical vapor deposition method forming a direct contact between them. This is realized by depositing a small amount of metal nanoparticles that catalyzes the growth of this carbon nanostructure on the surface of MgO. The successful synthesis of graphene was investigated by high resolution transmission electron microscopy and scanning electron microscopy. The thermal conductivity tests were performed using a transient plane source thermal characterization technique. We show that the material prepared by this method gives better heat conduction as compared to the individual mixing of these components.

International audience; RuO2 nanowires are synthesized by oxidation of ruthenium thanks to a micro-post-discharge at atmospheric pressure. However, RuO2 nanowires form islands. The growth mechanism depending on surface defects, the surface density of the nanowires is limited. We report on the influence of two alkali salts, NaCl and KCl, deposited as grains on ruthenium to act as defects and increase the nanowire density. These grains induce the growth of RuO2 nanowires all around them, creating a circular area where nanowires are found. Nanowires start growing at the triple point at the grain base where the alkali-salt grain, ruthenium from the substrate and oxidizing gaseous species coexist. When nanowires grow, the stress induced in the surrounding layer creates new cracks, making possible the radial propagation of the nanowires. The presence of nanowires on grains is due to the etching mechanism that converts the alkali salt into an oxide, enabling onward oxidation of ruthenium.

Core–shell nanoparticles are synthesized by nanosecond-pulsed discharges in liquid nitrogen using a two-step process. In a first step, copper nanoparticles (resp. zinc nanosheets) are synthesized by eroding pure copper (resp. zinc) electrodes. In a second step, copper (resp. zinc) electrodes are removed and replaced by zinc (resp. copper) electrodes in the liquid loaded with copper nanoparticles (resp. zinc nanosheets). After erosion and air oxidation, once nitrogen has evaporated, Cu@ZnO core–shell nanoparticles are obtained in both configurations. The shell is always ZnO, because of the unusual formation of zinc nanosheets instead of zinc nanoparticles. When Cu electrodes are used first, copper nanoparticles are wrapped in ZnO nanosheets. When Zn electrodes are used first, copper nanoparticles hit zinc nanosheets and get coated to form also Cu@ZnO. In this latter case, Cu 2 O@ZnO are sometimes encountered too but to a much lesser extent. Copper oxidation is then attributed to a failure in the zinc protective shell. Time-resolved optical emission spectroscopy measurements reveal that Cu lines and Zn lines are never emitted simultaneously, the element in the liquid remaining outside the discharge area. If zinc nanosheets are synthesized first, N II lines are exclusively observed during the first 200 ns of discharges with copper electrodes, revealing for this process the possibility of highly energetic processes.

The family of AM4Q8 chalcogenide Mott insulators gained attention in recent years for its application opportunities. Here, we explore and validate the resistive switching mechanism of thin-film of GaV4S8 sandwiched between TiN electrodes. The device is fabricated via processes and materials compatible with microelectronics standards and demonstrates a good control and endurance of the non-volatile transitions over a large range of resistance. The achieved multi-level property enables to envision application as Resistive Random Access Memories (RRAM) or neuromorphic applications. We also showed the important role of the current compliance in the control of the transitions.

Synthetic organic and inorganic carriers often have limitations associated with problematic targeting ability or non-optimized pharmacokinetics, and, therefore, they have restricted therapeutic potential. Natural drug carriers (e.g. mesenchymal stem cells, MSCs) are able to migrate towards the tumor site and penetrate cancerous cells. These biomimetic features make MSCs an attractive delivery platform that allows achieving maximal therapeutic efficiency with minimal toxic side effects. A combination of MSCs exhibiting a homing effect on tumors with stimuli-responsive nanostructured carriers is foreseen to have a huge impact in the field of personalized oncology. Here we develop for the first time a light-sensitive biomimetic delivery platform based on MSCs impregnated with submicron sized composite capsules containing an antitumor drug. This cell-based delivery system triggers the release of the drug upon near-infrared (NIR) laser irradiation due to gold nanorods (Au NRs) incorporated into the capsule wall. The NIR-triggered release of the antitumor drug such as vincristine leads to the effective mortality of tumor spheroids made of primary melanoma cells. Encapsulated vincristine delivered by MSCs into the tumor spheroids and deployed over the whole spheroid upon NIR exposure represents a promising therapy for the improved treatment of malignant neoplasms.

6 Figuras, 3 Tablas.-- Material suplementario disponible en línea en la página web del editor.-- © 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/, Interesting sensing performances of indoor formaldehyde pollution were obtained when small amounts of zinc were introduced in tin oxides. Nanostructured Sn oxide-based porous materials doped with Zn or not, were synthesized using hydrothermal routes. The physicochemical properties of the as-prepared metal-oxide materials were characterized using nitrogen adsorption, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Gas sensors were prepared using the aforementioned tin oxide materials and they exhibited a high sensitivity to formaldehyde at 230 °C, as well as a good repeatability over the time. Their limit of formaldehyde detection was as low as 8 ppb in dry air and 50 ppb in air with 60% RH at 25 °C. These results were much better that those reported in the open literature and they were attributed to both higher area BET, around 180 m2/g, and smaller crystallite size, 3.1 nm., The IJL research team gratefully acknowledges the financial support of the CPER 2007–2013 “Structuration du Pôle de Compétitivité Fibres Grand’Est” (Competitiveness Fibre Cluster), through local (Conseil Général des Vosges), regional (Région Lorraine), national (DRRT and FNADT) and European (FEDER) funds. Part of this work was also supported by CHEERS and TALiSMAN projects (FEDER funds). Dr. Angela Sanchez - Sanchez acknowledges the University of Lorraine, the Region Lorraine and the CNRS for financing her postdoctoral contract.

International audience; The present work reports on the low-pressure, radio-frequency, plasma-driven synthesis of ε-Fe 3 N-type nano-particles homogeneously deposited on a high-surface-area porous carbon support, with tunable magnetic properties, directly depending on the plasma treatment conditions. Iron nanoparticles are formed from the degradation of a solid organometallic precursor mixed with a carbon xerogel in a nitrogen-containing (argon/ammonia) plasma discharge. Variation of the working pressure during the plasma treatment directly affects the residence time of the reactive species, which determines the crystalline state of the nanoparticles, from amorphous at low-pressure treatment to well crystallized at high-pressure treatment. This results in a direct influence of the magnetic properties of the iron nitride nanoparticles. The working pressure results in two competing effects because it enhances the crystallinity (at higher pressure) and also slightly affects the surface chemistry of the nanoparticles by increasing the oxygen content, while the last is believed to deteriorate the magnetic properties; however, the crystallinity enhancement dominates. The synthesized Fe x N/C XG magnetic composites have been applied as filler materials in alginate membranes for ethanol dehydration in a pervaporation experiment. Results indicate a considerably enhanced performance of the alginate membrane as determined by its selectivity, the separation index, and the flux even when using a small Fe x N/C XG loading (3% w/w).

International audience; Here, we study the stress‐induced self‐organization of Mg2+ and Ni2+ cations in the crystal structure of multiwalled (Mg1–x,Nix)3Si2O5(OH)4 phyllosilicate nanoscrolls. The phyllosilicate layer strives to compensate size and surface energy difference between the metal oxide and silica sheets by curling. But as soon as the layer grows, the scrolling mechanism becomes a spent force. An energy model proposes secondary compensation of strain: two cations distribute along the nanoscroll spiral in accordance with preferable radii of curvature. To reveal this, we study synthetic (Mg1–x,Nix)3Si2O5(OH)4 nanoscrolls by the scanning transmission electron microscopy/energy‐dispersive X‐ray spectroscopy (STEM/EDS) technique. For a number of scrolls, we have found indeed a change of Ni concentration with increase in distance from the nanoscroll central axis. The concentration gradient, according to our estimates, can reach 50 at.% over 25 nm of the wall thickness.

International audience; In this work, a fast (0.5 h), green microwave-assisted synthesis of single crystalline Sb2Se3 nanowires was developed. For the first time we demonstrated a facile solvent-mediated process, whereby intriguing nanostructures including antimony selenide (Sb2Se3) nanowires and selenium (Se) microrods can be achieved by merely varying the volume ratio of ethylene glycol (EG) and H2O free from expensive chemical and additional surfactant. The achieved uniform Sb2Se3 nanowire is single crystalline along [001] growth direction with a diameter of 100 nm and a length up to tens of micrometers. When evaluated as an anode of lithium-ion battery, Sb2Se3 nanowire can deliver a high reversible capacity of 650.2 mAh g−1 at 100 mA g−1 and a capacity retention of 63.8% after long-term 1000 cycles at 1000 mA g−1, as well as superior rate capability (389.5 mAh g−1 at 2000 mA g−1). This easy solvent-mediated microwave synthesis approach exhibits its great universe and importance towards the fabrication of high-performance metal chalcogenide electrode materials for future low-cost, large-scale energy storage systems.

International audience; In the present study, the used graphene nanoplatelets (GNP) are of high structural quality offering the opportunity to modify the adsorbent/adsorbate interactions. Their chemical modification by simple acid oxidation leads to their facile dispersion in water. Morphological, structural and chemical properties of the functionalized GNP are deeply investigated by a set of complementary characterization techniques. The parametric investigation including effects 2 of initial concentration, contact time, solution pH and temperature of methylene blue (MB) adsorption allows to identify those being relevant for MB removal enhancement. MB adsorption is found to increase with contact time, solution temperature and acidic pH. The nature of the MB-GNP interactions and the possible adsorption mechanisms, relatively little understood, are here particularly studied. MB-GNP adsorption is shown to follow a Langmuir isotherm and a pseudo-first-order kinetic model. The adsorption capacity of MB on the chemically modified GNPs (qm=225 mg/g) with respect to the external surface is relatively high compared to other carbon nanomaterials. Such adsorbent certainly merits further consideration for removal of other dyes and heavy metals from wastewaters.

International audience; Purity of carbon nanotubes (CNTs) is essential to avoid a dramatic decrease in their performances. In addition to metallic impurities, carbonaceous impurities have been shown to be responsible for pronounced effects. However, they are highly difficult to be selectively removed from CNT samples because of the similar chemical reactivity of these two kinds of carbon species. The existing purification methods often lead to high CNT consumption (>90 wt %). The proposed method consists of a one-pot gas-phase treatment combining chlorine and oxygen. The CNT powder maintained in a chlorine stream is submitted to oxygen at moderate temperature [350 and 500 °C for single-walled CNTs (SWCNTs) and double-walled CNTs (DWCNTs), respectively], and the thermal treatment is then pursued at 900–1000 °C under chlorine alone. Our work reveals that this approach is able to significantly improve the selectivity of elimination of carbonaceous impurities. Thanks to the proposed purification treatment, only 19 and 11 wt % of carbon species (mainly carbon impurities) are lost for DWCNTs and SWCNTs, respectively. The mechanism proposed involves a protective effect by grafting of chlorine favored to the CNT walls. Because our simple one-pot purification method is also versatile and scalable, it opens new perspectives for CNT applications in high-added value fields.

5 Figuras.-- Material suplementario disponible en línea en la página web del editor., Ordered mesoporous carbons (OMCs) are produced by an easy, fast, and green surfactant-water-assisted mechanochemical mesostructuration (SWAMM) method, using only tannin, water, and Pluronic F127 as raw materials. OMCs are physically activated with CO2 to increase their surface area from ∼500 to ∼2000 m2 g–1 while maintaining the mesoporosity fairly unaltered, which allow studying the effect of the micropore size distribution on the performance of supercapacitors both in aqueous and organic electrolytes. Selected activated OMCs (AOMCs) reach maximum cell capacitance values of 37 and 27 F g–1, at 0.2 A g–1, in aqueous and organic electrolytes, respectively. High long-term stabilities over time and after continuous cycling are found for the tested AOMCs in both kinds of electrolytes. High-rate capabilities are achieved at high current densities with capacitance retentions up to 70% at 80 A g–1 and 44% at 40 A g–1 in aqueous and organic electrolytes, respectively, because of suitable pore size distribution that promotes ion diffusion into the electrodes, in particular for the material activated during 75 min., J.C.-G. gratefully acknowledges CONACYT-SENER (601021/438978) for the assigned scholarship to support her PhD studies, resulting in the work presented herein. This study was partly supported by the French PIA project “Lorraine Université d’Excellence”, reference ANR-15-IDEX-04-LUE, and the TALiSMAN project, funded by FEDER (2019-000214). M.S. thanks funding by the Spanish MINECO-FEDER (CTQ2015-63552-R).

Transparent nanoscale-film heterojunctions based on Cu2O and ZnO were fabricated by atomic layer deposition and reactive magnetron sputtering. The constitutive layers exhibit high crystalline quali...

International audience; The increased need for protecting cutting tools has led to the development of more and more efficient coatings. Ti-Al-N is one of the most studied systems in the hard coating industry due to the high hardness and good oxidation resistance of Ti1−xAlxN coatings. The development of LPCVD processes has led to the discovery of new microstructures and morphologies. In this study, we discuss the microstructural and morphological changes caused by varying the aluminum content in films deposited by low pressure thermal CVD in an industrial reactor at low carrier gas flow and relatively high pressure (>4 kPa). Coatings were characterized using FE-SEM, XRD and TEM analysis, revealing the growth of nanolamellae with modulated Al and Ti contents for the lowest Al containing coatings. The coatings with the highest Al contents were also found to show particular cube-shaped grains with a micromodulation of composition. Experimental Al content values are higher than the calculated one and their evolutions with the AlCl3/(AlCl3 + TiCl4) molar ratio are similar. The hardness and oxidation resistance were characterized and compared with available data in literature. Higher hardness is obtained for coatings having an Al content up to x = 0.65 and a hardness drop is found for higher Al contents. The oxidation resistance of the coatings rises continuously with an increasing Al content.

International audience; Hereby, a facile one step synthesis of polyoxazoline coated Superparamagnetic Iron Oxide Nanoparticles is reported. The functionalization efficiency is demonstrated using several complementary techniques including direct High Resolution-Transmission Electron Microscopy observations of the polyoxazoline layer. The hybrid nanoparticles have a spinel Fd-3 m structure, a mean particle size of around 12 nm and a high saturation magnetization of 72 emu/g.

International audience; The precise quantification of catalyst residues in purified carbon nanotubes is often a major issue in view of any fundamental and/or applicative studies. More importantly, since the best CNTs are successfully grown with magnetic catalysts, their quantification becomes strictly necessary to better understand intrinsic properties of CNT. For these reasons, we have deeply analyzed the catalyst content remained in nickel-yttrium arc-discharge single walled carbon nanotubes purified by both a chlorine-gas phase and a standard acid-based treatment. The study focuses on Ni analysis which has been investigated by transmission electron microscopy, X-ray diffraction, thermogravimetry analysis, and magnetic measurements. In the case of the acid-based treatment, all quantifications result in a decrease of the nanocrystallized Ni by a factor of two. In the case of the halogen gas treatment, analysis and quantification of Ni content is less straightforward: a huge difference appears between X-ray diffraction and thermogravimetry results. Thanks to magnetic measurements, this disagreement is explained by the presence of ions, belonging to NiCl2 formed during the Cl-based purification process. In particular, NiCl2 compound appears under different magnetic/crystalline phases: paramagnetic or diamagnetic, or well intercalated in between carbon sheets with an ordered magnetic phase at low temperature.

The room temperature growth of highly oriented sputtered NiO thin films on glass and silicon substrates previously covered with a oriented Cu2O film is reported. The results are compared to those obtained from single layer NiO thin films using the same deposition conditions. Electron microdiffraction analyses indicate that NiO columns are heteroepitaxially grown on the columns of a Cu2O seed layer. The well-matched atomic configurations between the Cu atoms in the {111} planes of Cu2O and the O atoms in the {111} planes of NiO may provide a strong driving force to promote this local heteroepitaxial growth. Such heteroepitaxial growth behavior in the columns can significantly improve crystallization. Moreover, valence electron energy loss spectroscopy has been employed to investigate the interband transition properties of the NiO films, which shows that the interband transition intensity can be tuned by this local heteroepitaxial growth.

In this work, ZnS:Cu thin films were synthetized by RF magnetron co-sputtering using ceramic ZnS and metallic Cu targets. The power applied to Cu target was changed to vary the Cu content in the films while other experimental parameters remain constant. Whatever the copper content, only the hexagonal ZnS phase was detected by X-ray diffraction and the films are oriented along the c-axis. For films with a Cu content higher than 10.6 at%, the a and c lattice parameters of the crystal cell decrease leading to a shrinkage of the ZnS:Cu cell. Changes in the microstructural, optical and electronic properties of the films are also observed. Regarding the optical properties, the energy bandgap determined by optical absorption decreases with the Cu content. Moreover, an absorption in the near infrared region appears probably due to a plasmon resonance coming from an increase of the holes carrier concentration. From electrical measurements it was found that above a copper concentration of 10 at%, the films are conductive and exhibit a p-type behavior. These results were discussed taking into account the substitution of Zn atoms by Cu ones. Finally, electron energy loss spectrometry measurements clearly showed that copper atoms are present in the ZnS lattice with an oxidation state of +I.

Discharges in liquid nitrogen between 2 electrodes made of either Cu, Ag or Cu28Ag72 enable the production of several types of comparable nano-objects. First, Cu nanoparticles (NPs) with sizes close to 5 ± 4 nm nm and 40 ± 10 nm are obtained with Cu electrodes and get oxidized in the air to form CuO after liquid evaporation. With Cu28Ag72 electrodes, copper contains a small amount of silver that inhibits oxidation. Next, silver nanoparticles are spherical but when doped with copper, they are facetted. Silver-containing nanowires have very similar features whether they are synthesized with silver or CuAg electrodes. They are made by assembly of NPs. Ag nanosheets are either single crystals in the case of CuAg electrodes or assembly of NPs in the case of silver electrodes. Finally, silver nanorods with traces of copper are only found with CuAg electrodes. Time-resolved optical emission spectroscopy indicates that the optical thickness decreases when copper is added to silver, lines appearing immediately after breakdown and not only after emission of a broad continuum. Emission of lines belonging to the N II system is then observed. The energy deposited being nearly constant, the structure of the discharge is assumed to be changed.

International audience; Copper surface after antibacterial test against E. coli was examined in the aspect of corrosion. Results from scanning electron microscope (SEM), grazing incidence X-ray diffractometer (GIXRD) and Raman spectroscopy together confirmed less oxidation on copper surface with the presence of E. coli. The inhibition of the cuprous oxide (Cu2O) layer instead ensured the continuous exposure of copper surface, letting localised corrosion attacks observable and causing a stronger release of copper ions. These phenomena are attributed to the fact that E. coli act as ions reservoirs since high amount of copper accumulation were found by energy dispersive X-ray spectroscopy (EDS).