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The present work reports a green biosynthesis of gold nano particles (EO-AuNPs) using an essential oil (EO) as a reducing agent of the Au(III) in HAuCl4. The EO was extracted by hydro-distillation from Diplotaxis acris flowers. A total of 16 compounds were detected from the EO oil by using GC–MS and 5-methylsulfanylpentanenitrile was identified as the major component (73.60 %). The biosynthesized EO-AuNPs were characterized performing UV–Vis, IR,XRD and TEM analyses.The UV-Vis revealed the typical features of surface plasmon resonance (SPR) of AuNPs at ~526 nm. The FT-IR spectrum of the biosynthesized nano particles exhibited the features of the nitrile (-C≡N) functional group indicating that the -C≡N-bearing EO components are likely acting as reducing and stabilizing agents for the formation of EO-AuNPs. The plausible scheme of EO-AuNPsformation was proposed.The TEM analysis showed that the EO- AuNPs were almost spherical in shape with an average particle size of 12.7 nm. In addition, the antimicrobial activity was carried out by diffusion of agar wells method. The results proved that the EO-AuNPs displayed a potential antimicrobial against gram negative strains, with a maximum zone of inhibition of 16 mm for E. coli at a concentration of 100 µg / ml.

The interest in belite (Ca2SiO4 + impurities or dopants) phase increases significantly since new types of clinkers based essentially on this phase become promising alternatives to Portland clinker for reducing CO2 emission. Belite is also of interest as a biomedical cement. For the cement industry, stabilization of the β-polymorph is essential since the γ-polymorph has no hydraulic activity. In order to understand the mechanism of β-polymorph stabilization, this paper explores the addition of three dopants, namely P, B and S. It turns out that these dopants can modify the lattice parameters of Ca2SiO4 and induce specific twinning morphologies and surface relief, as well as grain boundaries deformations. A link between the addition of dopant leading to significant microstructural changes and the stabilization of β-polymorph has been established.

Dicalcium silicate finds applications in different fields (cement, bio-ceramics, refractories). In the case of Portland cement, its interest is its lower sintering temperature compared to tricalcium silicate and therefore an interesting compound for low CO2 cements. Dicalcium silicate goes through different polymorphic forms, namely α, α'H, α'L, β and γ, as the temperature decreases. In theory, only the γ-phase is stable at room temperature. In a polycrystalline material, the different polymorphs can co-exist depending on several factors (sintering conditions, presence of impurities, grain size) and the interpretations given in the literature are sometimes contradictory. For cement applications, only the α, α' or β polymorphs react with water to give hydrates while γ does not. Therefore, this paper focuses specifically on the effect of grain size on the β to γ transformation. We also propose that the transformation is semi-reconstructive and not martensitic as suggested by some authors.

A set of Co substituted Ni–Zn nanoferrites with a nominal composition Co0.2Ni0.3Zn0.5Fe2O4 was prepared by the polyol method. The influence of a number of synthetic parameters on the structure, microstructure, and the magnetic properties was investigated. X-ray diffraction, infrared, energy dispersive X-ray, transmission electron microscopy, and vibrating sample magnetometry were employed for this purpose. The X-ray diffraction results confirmed the formation of a single phase nanocrystalline spinel-type ferrite powders. In addition, the cell parameter and the integrated intensity ratio I220/I422 was found to vary with the synthesis conditions suggesting deviation from the nominal chemical composition and/or a probable deviation from the preferential (that of the bulk) cations occupancy of the tetrahedral (A) and the octahedral (B) spinel sites. For the so-called bulk ferrite obtained by moderate sintering nanoparticles of the stoichiometric ferrite, a cation distribution similar to that of the bulk was suggested. Transmission electron microscopy analysis of the as-produced ferrites revealed the formation of nanoparticles with mean particle size in the range ~4–12 nm. The magnetic properties of both as-prepared nanoparticles and the so-called bulk ferrite were studied. All the as-produced particles exhibited superparamagnetic behavior at room temperature with a gradual decrease of the blocking temperature with the decrease of crystallite size. Additionally, the saturation magnetization, the coercivity, and the Curie temperature were found to be clearly dependent on the stoichiometry, the cations occupancy, and/or the grains morphology. For the stoichiometric ferrites the relatively higher Curie temperature values measured for the smaller particles was interpreted on the basis on the cations distribution change; for the as-produced nanoparticles a fraction of Zn2+ ions is expected to migrate from A to B sites accompanied with a reverse transfer of an equal amount of the paramagnetic cations from B to A sites.

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International audience; Polygonal-shaped about 75 nm sized and highly crystallized Eu3+-doped β-NaYF4 particles were directly prepared under mild conditions using the polyol process. A set of operating parameters were optimized for such a purpose. A conventional heating under reflux for 30 min of a mixture of Y(III) and Eu(III) acetate, ammonium fluoride, sodium hydroxide and oleic acid (OA) dissolved in ethyleneglycol offered a pertinent material processing route if a large excess of NH4F and an enough amount of OA were used. Typically, the former parameter provides an exclusive stabilization of the desired β allotropic form, while the latter allows a significant size decrease of the particles. Thanks to their coating by a double OA layer, the produced particles exhibited a hydrophilic surface feature when dispersed in water and when excited under UV light they emitted a very intense red photoluminescence. Additionally, they did not evidence any accurate cytotoxicity when incubated with healthy human foreskin fibroblast (BJH) cells for doses as high as 50 μg·mL−1 and contact time as long as 48 h, highlighting the ability of the prepared particles to be used as efficient down-converter light sources for cell labelling.

The effect of sintering conditions (the temperature and the pressure) on the electrical/dielectric and the magnetic properties of a nanocrystalline Co0.2Ni0.3Zn0.5Fe2O4 was studied. The XRD and EDX results confirmed a single phase nanocrystalline spinel-type ferrite structure of both the as-prepared polyol-made powder and its associated ones sintered between 773 and 1273 K. In addition, analysis of the integrated intensity ratios I220/I222 and I220/I422 indicated changes in the cation occupancy with sintering temperature variation. This result is supported by IR analysis. As expected, the mean particle size inferred from XRD and TEM increased with sintering temperature increase, it ranges from~2 nm for the as-prepared ferrite to~83 nm for the ferrite sintered at 1273 K. The electrical/dielectric properties were investigated over a wide range of frequency and temperature. The sintered ferrites showed a semiconductor behavior with conductivity following the Arrhenius law. At moderately sintering temperatures, the increase of conductivity was attributed to the increase Fe2+ concentration, while, at higher temperatures, the increase is mainly due to the decrease of porosity. The loss factor of our nanoferrites was found to decrease drastically with both the pressure and temperature of sintering showing better values than reported for similar ferrites. Magnetic measurements conducted on a VSM apparatus showed a superparamagnetic behavior at room temperature. In addition, the saturation magnetization was found to increase in a continuous manner with the sintering temperature increase consequence of particle size increase. Finally, the Curie temperature was found to vary slightly between 600 and 631 K, the chemical composition seems to be the main parameter influencing this feature.

Nowadays there is a continuously increasing worldwide concern for the development of efficient wastewaters treatment technologies. Among the heavy metal ions, chromium holds a distinct position due to its high toxic nature to biological systems. This study aims to assess magnetite derivatives nanoparticles for the removal of Cr(VI) species. Crystalline magnetite-rich (Magn) and pure maghemite (Magh) nanoparticles were produced by the polyol method and by subsequent heat treatment of Magn, respectively. The XRD analysis confirmed the formation of nanosized single phase cubic spinels with a cell parameter of 8.3710(2) A for Magn and 8.3401(2) A for Magh, consistent with those of a magnetite-rich ferrite and maghemite, respectively. TEM analysis showed that the two nanoferrites possessed comparable mean particle size of ∼15 nm. Magn and Magh showed superparamagnetic behavior at room temperature and reasonable saturation magnetizations at 300 K of 69 and 67 emu.g−1, respectively. The Curie temperature of both nanoferrites exceeded 350 °C allowing the materials to work in severe conditions. Room temperature, batch adsorption experiments of Cr(VI) onto maghemite nanoparticles were carried out at pH 2.0. Adsorption efficiency increased rapidly was the increase of the nanoparticles dose. For a 20 mg.L−1 Cr(VI) solution a 100% removal was found with ∼3 g.L−1 dose. Additionally, for a given dose (4.0 g.L−1), the adsorption rate measured as a function of time for different Cr(VI) concentrations was very rapid; ∼90% of removable Cr(VI) species was achieved within 10 min. The high rate of Cr(VI) uptake takes advantages of the high active surface chemistry of the nanoparticles. The adsorption of Cr(VI) onto Magh nanoparticles followed a pseudo-second order kinetics indicating a chemisorption process. Further, the Langmuir isotherm model was found to best describe the equilibrium data with a maximum adsorption capacity of 12.5 mg.g−1 for an adsorbent dosage of 4.0 g.L−1.

Highly crystalline CoxNi0.5−xZn0.5Fe2O4 (x=0.0, 0.2, 0.4) nanoparticles of about 5 nm in size were synthesized by the polyol method and subsequently sintered at 700 °C for 4 h. The structural, electrical, and magnetic properties of the sintered ferrites were investigated using various techniques including X-ray diffraction, thermal analysis, infrared and energy dispersive X-ray spectroscopies, transmission electron microscopy, and vibrating sample magnetometry. The lattice parameter increased linearly with Co content in agreement with increasing substitution of Ni2+ for Co2+. The sintered powders are composed of nanograins with average size ranging from ~30 to ~40 nm. The electrical study showed a resistivity decrease with increasing temperature indicating a semiconducting behavior. In addition, the dc conductivity was found to follow the Arrhenius law with a slope change observed at a critical temperature, the Curie temperature. The variation of the dielectric properties (dielectric constant and the dielectric loss) with frequency and temperature was explained on the basis of Maxwell–Wagner type of interfacial polarization. At room temperature, the best characteristics (high resistivity, high permittivity, and low loss factor) were found with the Co composition x=0.2. They were found to be considerably better than those of the unsubstituted Ni–Zn bulk ferrite. Magnetic investigation showed that all the sintered particles exhibit superparamagnetic behavior at room temperature. Additionally, the saturation magnetization and the Curie temperature showed similar trend; they increased slightly from x=0.0 to x=0.2 and then they decreased notably for the composition x=0.4. This can be attributed to the changes of superexchange interactions between cations in the spinel-type sublattices on Ni substitution.

International audience; The effect of sintering conditions (the temperature and the pressure) on the electrical/dielectric and the magnetic properties of a nanocrystalline Co0.2Ni0.3Zn0.5Fe2O4 was studied. The XRD and EDX results confirmed a single phase nanocrystalline spinel-type ferrite structure of both the as-prepared polyol-made powder and its associated ones sintered between 773 and 1273 K. In addition, analysis of the integrated intensity ratios I220/I222 and I220/I422 indicated changes in the cation occupancy with sintering temperature variation. This result is supported by IR analysis. As expected, the mean particle size inferred from XRD and TEM increased with sintering temperature increase, it ranges from~2 nm for the as-prepared ferrite to~83 nm for the ferrite sintered at 1273 K. The electrical/dielectric properties were investigated over a wide range of frequency and temperature. The sintered ferrites showed a semiconductor behavior with conductivity following the Arrhenius law. At moderately sintering temperatures, the increase of conductivity was attributed to the increase Fe2+ concentration, while, at higher temperatures, the increase is mainly due to the decrease of porosity. The loss factor of our nanoferrites was found to decrease drastically with both the pressure and temperature of sintering showing better values than reported for similar ferrites. Magnetic measurements conducted on a VSM apparatus showed a superparamagnetic behavior at room temperature. In addition, the saturation magnetization was found to increase in a continuous manner with the sintering temperature increase consequence of particle size increase. Finally, the Curie temperature was found to vary slightly between 600 and 631 K, the chemical composition seems to be the main parameter influencing this feature.

The present study evaluates the effects of iron oxide nanoparticles (ION) on mitochondrial respiratory chain complexes activities in five organs characterized by different oxidative capacities and strongly involved in body detoxification. Isolated mitochondria were extracted from brain, heart, lung, liver and kidneys in twelve Wistar rats (8 weeks) using differential centrifugations. Maximal oxidative capacities (Vmax), mitochondrial respiratory chain complexes activity using succinate (Vsucc, complexes II, III, and IV activities) or N, N, N', N'-tetramethyl-p-phenylenediaminedihydrochloride (tmpd)/ascorbate (Vtmpd, complex IV activity) and, mitochondrial coupling (Vmax/Vo) were determined in controls and after exposure to 100, 200, 300 and 500μg/ml Fe3O4. Data showed that baseline maximal oxidative capacities were 26.3±4.7, 48.9±4.6, 11.3±1.3, 27.0±2.5 and 13.4±1.7μmol O2/min/g protein in brain, heart, lung, liver, and kidneys mitochondria, respectively. Complexes II, III, and IV activities also significantly differed between the five organs. Interestingly, as compared to baseline values and in all tissues examined, exposure to ION did not alter mitochondrial respiratory chain complexes activities whatever the nanoparticles (NPs) concentration used. Thus, ION did not show any toxicity on mitochondrial coupling and respiratory chain complexes I, II, III, and IV activities in these five major organs.

Highly crystalline CoFe(2)O(4) nanoparticles with different diameters ranging from 2.4 to 6.1 nm have been synthesized by forced hydrolysis in polyol. The size can be controlled through adjusting the nominal water/metal molar ratio. X-ray diffraction, transmission electron microscopy, x-ray absorption spectroscopy and (57)Fe Mössbauer spectrometry were employed to investigate the structure and the microstructure of the particles produced. Magnetic measurements performed on these particles show that they are superparamagnetic with a size-dependent blocking temperature. At 5 K, high saturation magnetization (~85 emu g(-1)) approaching that of the bulk was found for the larger particles, whereas a very large coercivity (14.5 kOe) is observed for the 3.5 nm sized particles.

Crystalline and stoichiometric Co0.2Ni0.3Zn0.5Fe2O4 ferrite nanoparticles were successfully synthesised in polyol medium starting from the low-cost iron (III) chloride and acetates as precursors by the optimisation a number of synthetic parameters. The crystalline structure, the chemical composition, the microstructure, and the thermal stability of the as-produced powders were investigated by X-ray diffraction, infrared spectroscopy, energy dispersive X-ray, X-ray fluorescence spectroscopy, and transmission electron microscopy. We demonstrated that in contrast to the stoichiometric ferrite, which showed excellent thermal stability, the non-stoichiometric ferrites thermally decompose resulting in a stoichiometric ferrite as a major phase and hematite. The degree of deviation from the stoichiometry was calculated on the basis of a proposed decompositional thermal scheme and a quantitative analysis using Rietveld refinement.