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The study refers to the experimental investigation of solar photovoltaic collectors' behaviour when the glazed surface is treated with a nanometric layer of hydrophobic solution. The experiment was carried out on two photovoltaic collectors, of which one was considered as reference and the other one was coated with a commercial hydrophobic solution. It was studied the evolution of the following electrical parameters: current, voltage, power, efficiency and daily energy production. The voltage was almost unaffected, but for all the others parameters, important drop were recorded. The preliminary conclusion of the study is that the use of hydrophobic solutions, for the treatment of glazed surfaces of solar collectors is not recommended. This hypothesis needs supplementary investigations and measurements in the context of reduced available information concerning the optical properties of hydrophobic solutions.

International audience; Electrical properties of grain boundaries, free of any secondary phases, have been investigated in cubic nanostructured zirconia ceramics. Pure 8YSZ powders were synthesised by spray pyrolysis process. These powders were used to perform dense nanostructured ceramics using two compaction techniques: cold isostatic pressing (CIP) and hot uniaxial pressing (HUP) in an oxidising atmosphere. Grain sizes ranging from 25 to 242 nm and relative densities from 93 up to 98% were obtained. Electrical contribution of the bulk and the blocking effect due to grain boundaries were determined by impedance spectroscopy and analysed according to the brick layer model. The additional blocking effect is a decreasing function of the grain size but its magnitude reaches a plateau quite insensitive to the grain size below 100 nm. This indicates that the recorded electrical contribution originates from an intrinsic effect. This can be related to a dominant electrical contribution of space charge layers located at the grain boundaries area of nanoscale grain sizes.

The increasing technology node scaling makes VLSI devices extremely vulnerable to Single Event Effects (SEEs) induced by highly charged particles such as heavy ions, increasing the sensitivity to Single Event Transients (SETs). In this paper, we describe a new methodology combining an analytical and oriented model for analyzing the sensitivity of SET nanometric technologies. The paper includes radiation test experiments performed on Flash-based FPGAs using heavy ions radiation beam. Experimental results are detailed and commented demonstrating the effective mitigation capabilities thanks to the adoption of the developed model.

International audience; MolybdatesZn1-xCoxMoO4(0≤ x ≤0.3) were elaborated by the Sol-Gel method with pH=3.The results obtained by DRX show a single-phase domain startingfrom 500°C for x ≤ 0.3 isostructural to ZnMoO4.The powder ofZn0.7Co0.3MoO4treated at 500°C and 700°C is formed by nano-sized primary crystallitesof size between 80 and 160nm. The colorimetric parameters (L a* b*) of powders obtained at 700°C present adegree of high bluing.

International audience; The present paper deals with the preparation of nanometric yttria powders. A sol–gel method has been adopted to synthesize a precursor gel which, after being heated, leads to Y2O3. Two main parameters are taken into account: the nature of the chelating agent and the [chelating agent]/[Y] relative concentration. The influence of these parameters on the composition and crystallization state of the precursor gel has been studied in the first part and on the grain morphologies of the resulting yttria powder in the second part. It has been shown that, depending on the chelating agent, nanometric powders presenting either needles, platelets or spherical shapes can actually be obtained at 800°C or 1100°C.

International audience; Electrical properties of doped nanocrystalline ceramics of xR2O3–ZrO2 with 1≤x mol% final content≤3.5 of Sc2O3, Yb2O3, Y2O3, Gd2O3 and Sm2O3 were studied. Rare-earth oxide dopants were selected for their lower valence (+3) compared to Zr4+ and for an increase in their ionic radii ranging from 0.087 to 0.109 nm, respectively, from Sc3+ to Sm3+. This systematic study is focused on compositions defined as the minimal dopant concentration at which the tetragonal single-phase is stabilized. These ceramics are characterized by a good purity (quantity of Si less than 0.1 wt.%) and are found to be perfectly stable in temperature, keeping their microstructure constant. Impedance spectroscopy was used to determine the tetragonal zirconia matrix electrical contribution and the internal interface blocking effect. Both specific and blocking conductivities decrease when the dopant ionic radius is increased. The influence of space-charge layers on the increasing blocking effect was suggested.

Aluminum is used as a metal fuel in energetic materials for the improvement of propulsion performance and density. Both nano-sized and micrometer-sized activated powders represent valuable options in order to improve metal combustion properties, each possessing advantages and drawbacks. These ingredients bear peculiar properties (namely, higher specific surface, coatings, or surface characteristics) which generate high mixing viscosity once suspended in a polymer as well as altered mechanical properties of the final product. Four different powders dispersed in a polymer binder are taken into consideration and the evolution of viscosity in time during the curing process is investigated. The suspending medium is represented by a mixture of hydroxyl-terminated polybutadiene (HTPB), isophorone diisocyanate (IPDI) and dioctyl adipate (DOA). Viscosity was measured for 5 h on samples under isothermal curing at 60 °C. Non-isothermal DSC kinetic analyses were also performed using the Kissinger method. It was found that, for the test conditions, a size reduction of metal particles slowed down the increment rate of curing viscosity while some peculiar coatings, such as fatty acids, introduced opposite trends.

International audience; Dispersion and absorption are examined for dilute suspensions of Ultrasound Contrast Agents of nanometric size (nACUs), with typical radii around 100 nm. This new generation of contrast agents is designed for targeted delivery of drugs. Compared to standard contrast agents used for imaging, particles are of smaller size to pass the endothelial barrier, their shell made up of biocompatible polymer (PLGA) is stiffer to undergo a longer time life and they have a liquid (PFOB) instead of a gaseous core. Ultrasound propagation in dilute suspension of nACUs is modelled by combining i) a dilatational mode of oscillation assuming an incompressible shell with a visco-elastic behaviour of Maxwell type (relaxation), and ii) a translational mode of oscillation induced by visco-inertial interaction with the ambient fluid. Experimental measurements of the dispersion and absorption properties of nACUs solutions over the 1-100 MHz frequency range are performed for various temperatures and concentrations. They allow to fit with good accuracy three unknown parameters of the nACUs shell: the thickness, the Young modulus and the viscosity (or equivalently the relaxation frequency). Obtained values are compatible with literature data and offer insight into the behaviour of PLGA shells in suspension [Work supported by programme Emergence-UPMC].

The influence of confinement on biomolecule motion in glass channels of nanometric height has been investigated with fluorescence correlation spectroscopy (FCS). We measured intrachannel molecule diffusion time and concentration based on a single-component diffusion model as a function of molecule size to channel height (r(g)/h). Poly(ethylene glycol) (PEG) of 20 kDa and dextran of 40 kDa showed a reduction of their diffusion coefficients of almost 1 order of magnitude when nanochannel height approached probe diameter, whereas rhodamine 6G (Rh6G) was shown to be almost unaffected from confinement. Subdiffusive motion has been proven for flexible molecules in nanochannels, and deviations toward a square root dependence of mobility with time for confinement up to molecule size r(g)/h approximately 0.5 were registered. Diffusion coefficient time dependence has been evaluated and described with a model that accounts for diffusion time increase due to molecule rearrangements related to molecule flexibility and surface interactions dynamics. The evaluation of the subdiffusive mode and the key parameters extracted at the single-molecule level of partitioning, intrachannel diffusion time, desorption time, and binding probability at surfaces can be exploited for the engineering of bioanalytic nanodevices.

The product quality of energetic materials is predominantly determined by the crystallization process applied to produce these materials. It has been demonstrated in the past that the higher the product quality of the solid energetic ingredients, the less sensitive a plastic bonded explosive containing these energetic materials becomes. The application of submicron or nanometric energetic materials is generally considered to further decrease the sensitiveness of explosives. In order to assess the product quality of energetic materials, a range of analytical techniques is available. Recent attempts within the Reduced-sensitivity RDX Round Robin (R4) have provided the EM community a better insight into these analytical techniques and in some cases a correlation between product quality and shock initiation of plastic bonded explosives containing (RS-)RDX was identified, which would provide a possibility to discriminate between conventional and reduced sensitivity grades. In this paper experimental results of two relatively new crystallization techniques are shown. Submicron and nanometric RDX particles have been produced and characterized. Also results on the characterization of different commercial RDX grades will be shown, including data related to a part of the samples received within the R4 programme. Finally, experimental data will be presented and discussed on insensitive plastic bonded explosives (PBXs). © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

The product quality of energetic materials is predominantly determined by the crystallization process applied to produce these materials. It has been demonstrated in the past that the higher the product quality of the solid energetic ingredients, the less sensitive a plastic bonded explosive containing these energetic materials becomes. The application of submicron or nanometric energetic materials is generally considered to further decrease the sensitiveness of explosives. In order to assess the product quality of energetic materials, a range of analytical techniques is available. Recent attempts within the Reduced-sensitivity RDX Round Robin (R4) have provided the EM community a better insight into these analytical techniques and in some cases a correlation between product quality and shock initiation of plastic bonded explosives containing (RS-)RDX was identified, which would provide a possibility to discriminate between conventional and reduced sensitivity grades. In this paper experimental results of two relatively new crystallization techniques are shown. Submicron and nanometric RDX particles have been produced and characterized. Also results on the characterization of different commercial RDX grades will be shown, including data related to a part of the samples received within the R4 programme. Finally, experimental data will be presented and discussed on insensitive plastic bonded explosives (PBXs). © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

International audience; A systematic study of the influence of the rare-earth (Sc, Yb, Y, Gd, Sm) dopant content and the ionic radius on the structural changes was undertaken on nanocrystalline-doped zirconia ceramics, which present the same microstructure. Tetragonal single-phased ceramics which were prepared by sintering of nano-powders obtained by spray pyrolysis at 1500 °C for 2 h in air, are characterized by an average grain size as low as 60 nm. Their densities are about 96% of the theoretical values. A good homogeneity in composition and in grain size was obtained for all samples. This exceptionally low grain growth during the sintering was related to the high purity of the materials and also to the morphology of the powders. Tetragonal solid solution domains were determined from Differential Thermal Analysis (DTA), X-ray Diffraction (XRD), and Raman spectrometry measurements. The size of the solid solution domain depends on the dopant ionic radius and on the grain size.