Sébastien Pairis

Zinc distribution and speciation in Arabidopsis halleri × Arabidopsis lyrata progenies presenting various zinc accumulation capacities

The purpose of this study was to investigate the relationship between the chemical form and localization of zinc (Zn) in plant leaves and their Zn accumulation capacity. An interspecific cross between Arabidopsis halleri sp. halleri and Arabidopsis lyrata sp. petrea segregating for Zn accumulation was used. Zinc (Zn) speciation and Zn distribution in the leaves of the parent plants and of selected F(1) and F(2) progenies were investigated by spectroscopic and microscopic techniques and chemical analyses. A correlation was observed between the proportion of Zn being in octahedral coordination complexed to organic acids and free in solution (Zn-OAs + Zn(aq)) and Zn content in the leaves. This pool varied between 40% and 80% of total leaf Zn depending on the plant studied. Elemental mapping of the leaves revealed different Zn partitioning between the veins and the leaf tissue. The vein : tissue fluorescence ratio was negatively correlated with Zn accumulation. The higher proportion of Zn-OAs + Zn(aq) and the depletion of the veins in the stronger accumulators are attributed to a higher xylem unloading and vacuolar sequestration in the leaf cells. Elemental distributions in the trichomes were also investigated, and results support the role of carboxyl and/or hydroxyl groups as major Zn ligands in these cells.

Homogeneous Optical and Electronic Properties of Graphene Due to the Suppression of Multilayer Patches During CVD on Copper Foils

By limiting the carbon segregation at the copper surface defects, a pulsed chemical vapor deposition method for single layer graphene growth is shown to inhibit the formation of few-layer regions, leading to a fully single-layered graphene homogeneous at the centimeter scale. Graphene field-effect devices obtained after transfer of pulsed grown graphene on oxidized silicon exhibit mobilities above 5000 cm^2.V^-1.s^-1.

Magnetic properties of the UNS S39205 duplex stainless steel

Abstract Duplex stainless steels (DSS) present a fine microstructure of paramagnetic austenite and ferromagnetic ferrite. In this work the microstructures of UNS S39205 (old S31803) duplex stainless steel (DSS) samples were modified by high temperature treatment at 1300xa0°C in vacuum followed by four different cooling rates and thermal aging at 475xa0°C for three different times. Magnetic properties (saturation magnetization, remanence, coercive force and magnetic transition temperature) are reported. A relationship between the magnetic saturation and the ferrite volume fraction (Cα) was proposed. An increase in the Curie temperature (Tc) was observed during the aging at 475xa0°C in the fast cooled samples, but not in the slowly cooled ones, where the Cα was too low.

Structural investigations by neutron diffraction of equi-atomic Zr–Ti(V)–Ni(Co) compounds and their related hydrides

Abstract Crystal structure refinements based on neutron diffraction experiments performed on the ternary compounds ZrTiNi, ZrVCo and ZrVNi allow to confirm the stability of the C14 Laves type of structure in a large extent of formula. Besides, SEM/EDX analyses reveal the presence of minor additional phases that precipitate parallel to the main one. Neutron diffraction experiments performed on the corresponding ZrMM′ hydrides indicate that after hydrogen (deuterium) absorption the crystal structure remained unchanged, except for ZrTiNi, where further investigations are underway.

Fabrication and characterization of a Ni-Mn-Ga uniaxially textured freestanding film deposited by DC magnetron sputtering

Homogeneous freestanding films have been obtained by the direct current (DC) magnetron sputtering technique using a sacrificial layer. After annealing, the films are crystallized with a strong out-of-plane texture along the (022) direction. The stoichiometry of the annealed films is close to the target composition and leads to a martensitic transformation around 255K. The annealed films demonstrate ferromagnetic behavior with a Curie temperature of about 362K. The magnetization process has been studied on the both states and during the martensitic transition. The saturation magnetizations have been determined by fitting the experimental data with a saturation approach law in the range 1-5T. Results show the saturation magnetization of the martensite is around 10% higher than that of the austenite. A model based on intrinsic magnetic properties of each state allowing the description of the magnetization M=f (H, T) of such polycrystalline films during the martensitic transformation is presented. The mass fraction of martensite inside the austenite phase can be determined using this model. The shape memory effect is analyzed both by scanning electron microscopy and by optical microscopy with in-situ measurement of the resistance temperature dependence.

LZO, a Protective Barrier Against Oxidation of NiW Alloys

Low cost Coated Conductors (CC) are required to access competitive superconducting cables. The buffer layer architecture is a key aspect of CC processing and very efficient results have been obtained with complex architecture. However, it may not be useful to have so high Jc for cable applications, and then simpler architectures have been considered. Our group has suggested in 2008 that only one buffer could be sufficient. As the deposition of YBCO needs an oxygenated atmosphere at rather high temperature, it is a key stage to study the oxygenationseffects on the buffer layer. The aim of this study is to show results of annealing La2Zr2O7/NiW substrates (LZO/NiW), with LZO deposited by MOD, under different oxygen atmospheres and conditions closed to those used in MOCVD YBCO deposition. The microstructure of the buffer layer is studied in details and tentatively related to oxidation behavior. It is shown in addition that the substrate plays in fact a crucial role, grain boundaries being the main source of oxidation. We anticipate that perhaps oxidation is an important source of degradation of critical current in YBCO.

Effect of the isoelectronic substitution of Sb for As on the magnetic and structural properties of LaFe(As1−xSbx)O

The antiferromagnetic (AFM) order and structural distortion in the LaFe(As

Annealing effect on the magnetic induced austenite transformation in polycrystalline freestanding Ni-Co-Mn-In films produced by co-sputtering

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Structural and dielectric properties of parylene-VT4 thin films

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Effect of twins in Ni substrates on the microstructure of La2Zr2O7 films for coated conductors

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