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The correlations between structural features, critical current density and pinning landscape of YBa2Cu3O7-δ and MgB2-based materials produced in the forms of bulk melt-textured (MT-YBCO) and polycrystalline (MgB2) blocks and wires with excellent superconducting characteristics were revealed. The impurity oxygen distribution, higher borides inclusions and carbon doping are most important for the critical currents and pinning forces in MgB2, while the twin density and the density of Y211 inclusions are relevant in MT-YBCO.

A recent paper devoted to unusual fine-scale tubular tunnels found in pyrope and almandine garnets suggested that the 5 to 100 μm diameter tunnels were produced by an endolithic organism that is able to chemically dissolve and penetrate the mineral, perhaps in search of nutrients. The hypothesized microbial boring of the garnets was based on the finding of endolithic remains in the tunnels, but boring alone does not adequately explain the linear, highly aligned or occasionally branched tunnels that have been imaged. We have prepared this short Letter, in the spirit of Occam’s Razor, to highlight the very probable role that dislocations play in the creation of such tunnels by preferential etching of a dislocation-rich deformation microstructure. The geometrical features of the tunnels possess all the characteristics of classical dislocation substructures that have been observed in natural and synthetic garnets.

The selection of plant species at mine sites is mostly based on metal content in plant parts. Recent works have proposed referring to certain ecological aspects. However, plant traits for plant metal-tolerance still need to be accurately assessed in the field. An abandoned Zn-Pb mine site in Gard (France) offered the opportunity to test a set of ecological criteria. The diversity of micro-habitats was first recorded through floristic relev&eacute, s and selected categorical and measured plant traits were compared for plant species selection. The floristic composition of the study site consisted in 61 plant species from 31 plant families. This approach enabled us to focus on seven wild plant species naturally growing at the mining site. Their ability to form root symbioses was then observed with a view to phytostabilization management. Four species were considered for phytoextraction: Noccaea caerulescens (J. et C. Presl) FK Meyer, Biscutella laevigata L., Armeria arenaria (Pers.) Schult. and Plantago lanceolata L. The metal content of their aerial and root parts was then determined and compared with that of soil samples collected at the same site. This general approach may lead to the development of a knowledge base for assessment of the ecological restoration trajectory of the site and can help in plant selection for remediation of other metal-rich soils in the Mediterranean area based not only on metal removal but on ecological restoration principles.

International audience; In polluted protected areas, using phytoremediation raises the question of the choice of the plant species to select. As an example, Atriplex halimus has been identified as a proliferative plant species that needs to be eradicated in the Calanques National Park (PNCal). Since it has been proven that the spontaneous populations of this plant species could phytostabilize shore waste deposits generated by past industrial activities within the PNCal territory, its status seems controversial, presenting a dilemma between biodiversity management of a protected area and ecological solutions for pollution management. To address this issue, we assessed the ability of A. halimus to grow on different soils from this territory, in order to estimate the potential invasiveness of this plant in this territory. Petri dish germinations and pot-growth experiments showed 50% germination of seeds collected on local individuals from the most polluted PNCal soil and 20% growth reduction of seedlings. Soil analysis showed that limitation of growth was caused by high pH value and sparsely available micronutrients as well as metal and metalloid contamination. Our results suggested that local populations of A. halimus may stabilize the highly metal and metalloid polluted salt-affected soils of the PNCal, with low seed germination potential lowering the eventuality of a propagation over the PNCal territory. As a consequence of this study, the administration of the PNCal decided not to remove A. halimus populations along the polluted coastline until another solution to prevent pollution dispersal had been found. This laboratory approach may be extended to other similar situations where plant species may be evaluated not only in term of phytoremediation potential but also in term of biodiversity preservation.

International audience; This study highlights the trace metal and metalloid (TMM) accumulation in Rosmarinus officinalis L. and its chemical responses when exposed to high levels of contamination. R. officinalis individuals growing along a gradient of mixed TMM soil pollution, resulting from past industrial activities, were analysed. Several plant secondary metabolites, known to be involved in plant tolerance to TMM or as a plant health indicator, were investigated. The levels of thiol compounds and phytochelatin precursors (cysteine and glutathione) in the shoots were measured in the laboratory, while a portable non-destructive instrument was used to determine the level of phenolic compounds and chlorophylls directly on site. The level of Pb, As, Sb and Zn contaminations within the soil and plants was also determined.The results highlighted a decrease of TMM translocation with increases of soil contamination. The concentration of TMM in the shoots followed the Mitscherlich equation and reached a plateau at 0.41, 7.9, 0.37, 51.3 mg kg−1 for As, Pb, Sb and Zn, respectively. In the shoots, the levels of thiols and phenols were correlated to concentrations of TMM. Glutathione seems to be the main thiol compounds involved in the tolerance to As, Pb and Sb. Phenols indices, using non-destructive measurements, may be considered as an easy way to establish a proxy to estimate the TMM contamination level of the R. officinalis shoots. The study highlights metabolic processes that contribute to the high potential of R. officinalis for phytostabilisation of TMM in contaminated areas in the Mediterranean.

Comprehensive experimental results of fully oxidized (up to YBa2Cu3O6,9-7) melt-textured YBaCuO materials with different microstructures are presented. These microstructures are built respectively: (1) with a high dislocations density but almost without twins (after high temperature treatment at 2 GPa) and (2) with a high twin density, but practically free from dislocations and stacking faults (after high temperature oxygenation at 10-16 MPa). It is shown that for attaining high critical current densities and fields of irreversibility (jc(H‖c, 0 T)=9·104 A/cm2, H irr=9.7 T at 77 K), a high twin density in YBa2Cu3O6.9-7 matrix of MT-YBCO is required. The density of twins in fully oxidized materials depends on the distances between Y2BaCuO5 inclusions, larger twin densities are related to shorter distances between inclusions. The influence of phase composition of the initial powder mixtures on the distances between Y2BaCuO5 inclusions have been characterized and discussed.

International audience; Astragalus tragacantha is a protected plant species in France that grows even in the trace metal and metalloid (TMM) polluted soils of the Calanques National Park (PNCal). Soils are mainly contaminated by lead, copper, zinc and arsenic. An ex situ experiment was conducted, firstly to determine the molecular responses and root traits involved in the TMM tolerance of this plant species by growing individuals in a soil from the surroundings of one of the brownfields of the PNCal, known as l’Escalette, where this plant species grows spontaneously. Secondly, in order to determine the plasticity of these responses, seeds were collected from three different populations, one at l’Escalette (polluted site), one from the Frioul archipelago (non-polluted, insular site) and one from La Seyne (non-polluted, littoral site). The results of this study confirmed the capacity of A. tragacantha to germinate and grow in TMM contaminated soils. Only moderate significant variations in chlorophyll and flavonol indices, proline content and antioxidant activities were detected between polluted and control soil conditions for all populations. The main driver for A. tragacantha TMM tolerance seemed to be its ability to be associated with root symbionts i.e. arbuscular mycorrhizal fungi and dark septate endophytes, corresponding to a nutrient-uptake strategy trait. This work provides support for the challenge of A. tragacantha conservation along the littoral of the PNCal, because increasing the number of A. tragacantha individuals would both increase vegetation cover of the polluted soils to reduce the pollution transfer and reinforce the populations of this species.

International audience; The mechanical properties of materials usually depend on the size of the considered object. Silicon, for instance, undergoes between the macroscopic and nanometer scales, a brittle-to-ductile transition at room temperature. Although essential for the constantly developing Si-based nanotechnologies, the origin of this remarkable behaviour change remains undetermined for several years. The observation of the mechanisms responsible for plastic deformation in nano-objects is indeed highly challenging at the microscopic scale. One needs controlling the deformation while identifying induced individual plastic events at the smallest scale during the first stages of plasticity. This work describes nano-compression experiments on 100 nm-diameter Si nanopillars followed by post-mortem analysis of the deformed specimens through SEM and atomic resolution TEM imaging. The observed plastic deformation disrupts the usual description of low-temperature undissociated-dislocations-mediated plasticity and is comforted by molecular dynamics calculations. These results shed a new light on the transition between ductile and brittle regimes in silicon by introducing the missing link between plasticity and fracture.

International audience; A field study was conducted along a fluorine gradient of soil pollution in Tunisia from Gabes, the most polluted site, to Smara, the reference site. Variations of fluoride (F) concentrations in soils were detected over one year in Gabes, Skhira and Smara. F concentrations in the aerial part of two native plant species, i.e. Erodium glaucophyllum and Rantherium suaveolens, were above the usual background concentrations. Bioaccumulation factors ranged from 0.08 to 1.3. With F concentrations in aerial parts up to 355 mg kg-1, both species may be described as Faccumulators. Both species showed an earlier vegetative growth in Gabes than in Smara. However, some difference between their strategies could be observed i.e. E. glaucophyllum shortening the period of its vegetative growth with an escape strategy and R. suaveolens decreasing its ratio of alive:dead parts potentially lowering the F toxicity by storage in dead cells. However, at a tissue level, mechanisms of tolerance were similar. Leaf section micrographs of both species showed a higher calcium accumulation in leaf midveins at Gabes than at Smara, confirming the role of calcium in plant F tolerance strategies.

This paper focuses on the dislocation configurations that show up during the annihilation of a perfect dislocation vacancy dipole. Indeed unexpected transient dislocation core structures can be evidenced out of the atomistic structures computed during this annihilation process. Using the Geometric Phase Analysis these dislocation configurations can be analysed as partial dislocations, resulting from the dissociation of a perfect dislocation with ½[110] Burgers vector, bounding a nano crack (or a point defect cluster) along a (111) shuffle plane. Those partial dislocations appear as to be associated with an incipient dissociation/crack present in the core of perfect shuffle dislocations. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

International audience; Perfect dislocations have been found controlling the plasticity of silicon at high stress. Such evidence has been obtained from a number of experiments and atomistic computations. This is also consistent with the larger Peierls stresses encountered by partial dislocations as compared to perfect dislocations at low temperatures. However at very high stress and in the same temperature range partial dislocation have been reported to occur in a few experiments as well as in some atomistic computations. The aim of this paper is to discuss in what situations partial dislocations can be nucleated, what could be the nuclei responsible for their nucleation and the conditions where partial dislocations could control the plastic deformation in the place of perfect dislocations.

International audience; This is an in natura study aimed to determine the potential of Rosmarinus officinalis for phytostabilization of trace metal and metalloid (TMM)-contaminated soils in the Calanques National Park (Marseille, southeast of France). The link between rosemary tolerance/accumulation of As, Pb, Sb, and Zn and root symbioses with arbuscular mycorrhizal (AM) fungi and/or dark septate endophytes (DSE) was examined. Eight sites along a gradient of contamination were selected for soil and root collections. TMM concentrations were analyzed in all the samples and root symbioses were observed. Moreover, in the roots of various diameters collected in the most contaminated site, X-ray microfluorescence methods were used to determine TMM localization in tissues. Rosemary accumulated, in its roots, the most labile TMM fraction in the soil. The positive linear correlation between TMM concentrations in soil and endophyte root colonization rates suggests the involvement of AM fungi and DSE in rosemary tolerance to TMM. Moreover, a typical TMM localization in root peripheral tissues of thin roots containing endophytes forming AM and DSE development was observed using X-ray microfluorescence. Rosemary and its root symbioses appeared as a potential candidate for a phytostabilization process of metal-contaminated soils in Mediterranean area.

The unexpected occurrence of extended stacking faults in silicon nanostructures at high stress and low temperature is discussed. It is shown that those stacking faults result from the operation of “composite” dislocation core structures. It is demonstrated that such cores allow for the propagation of partial dislocations in the shuffle set with the benefit of a low Peierls stress. A classical atomistic calculation confirms indeed that shuffle partial dislocations can move under a shear stress of about 3.3 GPa (5.5% shear strain) at room temperature.

Physical properties of nano-objects differ from what they are in bulk materials when the size decreases down to the nanometre scale. This behavioural change, named size effect, also applies to mechanical properties and has been evidenced in various materials. For instance, at low temperature, bulk silicon is known to be a brittle material while silicon nano-objects exhibit a ductile behavior. Although mechanical properties of silicon have been intensively studied over the last decades, the origin of this remarkable brittle-to-ductile transition at small scales remains, however, undetermined. In this article, a study of the plastic behaviour of nano-pillars is reported. The main results obtained from the combination of numerical calculations and experimental compression tests followed by atomically-resolved transmission electron microscopy imaging are described. We discuss the possibility for perfect dislocations to dissociate at low temperature and the underrated role of shuffle partial dislocations in plastic deformation of silicon. The formation of unexpected extended defects in the {115} planes with increasing plastic strain, also appears as a key-factor leading to the transition between ductile and brittle regimes at small scales.

International audience; The role of silicon (Si) in alleviating biotic and abiotic stresses in crops is well evidenced by empirical studies; however, the mechanisms by which it works are still poorly known. The aim of this study is to determine whether or not phytolith composition and distribution in wheat are affected by drought and, if so, why. Durum wheat was grown using hydroponics in the presence of polyethylene glycol (PEG)-6000 to perform a water-stress simulation. We developed an original method for in situ analysis of phytoliths in leaves via X-ray imaging. PEG was efficient in inhibiting water uptake by roots and creating stress, and prevented a small fraction of Si from being accumulated in the shoots. The application of Si with PEG maintained shoot and root fresh weights (FW) and relative water content at higher values than for plants without Si, especially at PEG 12%. Our data show that, under water stress in the presence of Si, accumulation of phytoliths over the veins provides better support to the leaf, thus allowing for a better development of the whole plant than in the absence of Si. The development of silicified trichomes in durum wheat depends primarily on the availability of Si in soil and is not an adaptation to water stress.

Different core structures have been evidenced in silicon which control, respectively, low and high temperature deformation. Indeed perfect shuffle dislocations have been found to build deformation microstructures in the temperature range and stress where silicon is usually brittle. In contrast, the plastic regime is controlled by dissociated glide set dislocations. This paper aims at relating the plastic properties of silicon to the core structure of dislocations and in particular to the existence and the properties of these two core structures.

International audience; The aim of this study was to develop an effective and non-destructive method for the selection of native Mediterranean plants with phytoremediation potential based on their spontaneous recovery capacities. The study site consisted in a mixed contaminated soils (As, Cu, Pb, Sb, Zn) in the vicinity of a former lead smelting factory abandoned since 1925 in the Calanques National Park (Marseille, southeastern France). We developed an integrated characterization approach that takes into account topsoil metal(loid)s (MM) contamination, plant community composition and structure and mesologic parameters without using destructive methods. From a statistical selection of significant environmental descriptors, plant communities were described and interpreted as the result of spontaneous recovery under multiple stresses and local conditions (both natural and anthropogenic). We collected phytoecological and MM topsoil data using field monitoring and geographic information system (GIS) on a pollution hotspot where natural plant communities occur. The results of the multivariate analysis performed between species and descriptors indicated that a century of MM pollution pressure produced a significant correlation with plant community dynamics in terms of composition, diversity and structure, leading to the co-occurrence of different plant succession stages. Thus, these successions seemed linked to the variability of anthropogenic disturbance regimes within the study site. We recorded high topsoil contamination heterogeneity at the scale both of the plot and of the whole study area that suggested a heterogeneous MM distribution pattern dependent on the source of contaminants and site environmental variability. We identified 4 spontaneous plant communities co-occurring through a MM contamination gradient that could be used later from degraded to reference communities to define ecological restoration target combined to phytoremediation applications with respect to local conditions. Our results suggested that some of the native plant species such as Coronilla juncea and Globularia alypum might be tolerant to high mixed MM soil concentrations and they could thus be used for phytostabilization purposes in polluted Mediterranean areas in regard to their life-traits. Our non-destructive methodology led both to the selection of tolerant native plant species and communities and identification of highly polluted priority intervention areas through the study site where phytostabilization should be implemented. Furthermore, by analyzing succession dynamics linked to contamination patterns throughout the area and spontaneous recovery of native tolerant vegetation, our methodology opens up broad perspectives and research fields for ecological restoration for Mediterranean protected and contaminated areas based on ecosystem trajectories and new approaches for the integrative management of polluted soils. (C) 2016 Elsevier Ltd. All rights reserved.

Silicon micropillars obtained by FIB from Floating Zone silicon single crystal have been deformed in situ in a SEM between room temperature and 400 °C. Pillars with axis were studied in order to promote single slip deformation. Mechanical data as a function of pillar diameter and surface deformation microstructures observed by SEM are reported. Yield stresses as a function of temperature are compared with those resulting from high-pressure tests (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The aim of this study was to investigate the properties of cultivated urban soils and metal concentrations in these soils and in roots and leaves of the crops Amaranthus cruentus (amaranth) and Hibiscus sabdariffa(roselle). The soil physicochemical properties showed a poor fertility rate of cultivated soils. The metal concentrations in soils were in the range of concentrations for uncontaminated agricultural soils. The ranges of concentrations of metals were as follows: Aluminium (Al), 239-1222 mg/kg; cadmium (Cd), Al > Mn > Zn > Cu >Pb; in roots, Al > Fe > Zn > Mn > Cu > Pb. Al and Fe were weakly bioaccumulated but their concentrations were high. Cu and Mn were more accumulated in leaves than roots for amaranth and roselle. The leaves of amaranth were found to accumulate soil Cu and Zn more efficiently than other tissues of both vegetables. The translocation factor was in the order: Mn > Cu > Fe > Zn > Al, and when this value was compared between amaranth and roselle, it was observed to be higher in amaranth than in roselle. The concentrations of the essential elements Cu and Mn in roselle, and Cu, Fe, Mn and Zn in amaranth indicate that these leafy vegetable are a good nutrient sources. Key words: Soil, edible vegetables, metals, bioconcentration factor (BCF), translocation factor (TF).

Type Ib synthetic diamonds from De Beers with a low dislocation density have been deformed under confining pressure under pressure of 5 GPa in a multianvil apparatus between 900 and 1200 °C and in a D-DIA experimental set up at 1100 °C and strain rate of 7 × 10−5 s−1. TEM observations of diamond deformed at 1100 °C, the lowest deformation temperature where plasticity was unambiguously evidenced are reported in this work. Two types of dislocations have been found to coexist: dissociated and perfect. No large stacking faults resulting from the dissociation splitting blow up under large stress have been observed. Numerous dipoles are found in the microstructure which can be built with perfect or dissociated dislocations. These results are discussed in relation with dislocation core configuration calculations.

It has been established that the oxygenation of the structure of YBa2Cu3O7−δ (Y123) textured ceramic materials under elevated pressure (up to 10–16 MPa) and high temperatures (700–900°C) for a relatively short time (72 h) makes it possible to attain the record superconducting (at 77 K in the ab plane of Y123 phase jc ≈ 100 kA/cm2 (0 T), 55 kA/cm2 (2 T) and Hirr 9.5 T) and mechanical (microhardness up to HV = 7.6 GPa and fracture toughness up to KIc = 4.4 MPa·m0.5 under 4.9 N) properties. The high material characteristics have been explained by the formation of a nanostructure from twins acting as pinning centers (the density of twinning being 20–35 m−1) and a considerably smaller amount of microcracks (< 0.2 m−1) as well as by prevention of macrocracking.

4H-SiC intrinsic homoepitaxied single crystals have been nano indented at room temperature using a spherical indentor and the related deformation microstructures have been analyzed by Transmission Electron Microscopy. Dislocations are lying in the basal plane but have been found to be perfect, in contrast with observations made at higher temperature. Although such a change in deformation mechanism has been observed in other semiconductors such as Silicon and Indium Antimonide, it was unexpected in a very low stacking fault material such as SiC.

Results of deformation experiments on 4H-SiC single crystals below the usual brittle to ductile transition temperature are reported and discussed in comparison of previous literature data. Si-core and C-core partials are evidenced in the basal plane, and perfect dislocations are also observed on other crystallographic planes. These results could indicate that dislocation activity under high stress is more complex than expected.

Indium antimonide (InSb) has been plastically deformed over a wide temperature range, from 400 down to −176 °C (see the companion paper: Kedjar B, Thilly L, Demenet JL, Rabier J. Acta Mater 2009) and transmission electron microscopy was used to characterize the deformation microstructures. In the ductile regime, i.e. T > T tr1 ≈ 150 °C, the crystal deforms via the nucleation and motion of perfect dislocations belonging to the glide set. In the brittle domain, i.e. for T T tr1 ≈ 150 °C, two regimes are observed: for T tr2 ≈ 20 °C T T tr1 ≈ 150 °C, the crystal deformation takes place via the nucleation and glide of dissociated perfect dislocations or only leading partials, while for T T tr2 ≈ 20 °C, the crystal deformation proceeds via the nucleation and motion of perfect dislocations belonging to the shuffle set. In view of these observations, the brittle-to-ductile transition (at T tr1 ) is confirmed to correspond to a change in the dislocation nature in the glide set, from partial-mediated plasticity at low temperature to perfect-mediated plasticity at high temperature. Another transition is observed at T tr2 and corresponds to the glide-to-shuffle transition which is observed experimentally for the first time in a III–V compound semiconductor.

Highway detention ponds can fill with sediments from runoff water loaded with traffic-related materials. Sediment disposal is problematic and various protocols are currently studied, including phytoremediation. Here we present a preliminary study on four highway detention ponds in southern France to identify key sediment characteristics. Our objectives were to characterize metal content and physicochemical properties of the sediments and to evaluate the role of charophytes, which grow spontaneously in ponds, on metal lability. Vegetated and non-vegetated areas were compared. The lability of Mn, Cu, Zn, and Pb complexes was greater in the presence of charophytes. No variation in grain size composition was observed between non-vegetated and vegetated areas. These results may be useful to implement a phytoremediation strategy using those spontaneous charophytes. Our results suggest that local factors may impact sediment characteristics: for instance, strong gusts of wind, typical of southern France climate, may blow particles (some of them not related to traffic) in and out of detention ponds.

An analysis of the morphology of the extended defects revealed behind dislocation in the slip plane of silicon is presented. These extended defects show an electrical activity contradictorily to dislocations themselves; this is confirmed by Electron Induced Surface Potential (EISP) measurements. It is shown, that the generation of these extended defects is a common phenomenon for diamond lattice materials. The defects generation which has to be elucidated is considered to be relevant to a dynamical dislocation core structure during the plastic deformation of semiconductor materials with covalent lattice. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The possibility to oxygenate the YBa2Cu3O7−δ(Y123) structure to 7−δ ≈ 6.9 atoms (which ensures the highest temperature of transition into the superconductive state of this compound) at high temperature (800°C) and relatively low pressure (16 MPa) of oxygen has been first shown. This fact differs from the generally accepted notions of the equilibrium in the given system. It has been found that the MT-YBCO oxygenation at enhanced pressures and high temperatures decreases the oxygenation time and the amount of cracks and increases the twin density in the material, which positively affects the critical current density and mechanical characteristics of the ceramics. The experiments have shown that twins are largely responsible for high density of the critical currents j c and irreversibility fields in the MT-YBCO ceramics. In the case of high dislocation density (1012 cm−2) and low twin density (0–1 μm−1) in the Y123 structure, the critical current turned out to be an order of magnitude lower than in the case of high twin density (22 μm−1) and absence of dislocations and stacking faults. The density of twins and microcracks (parallel to the ab plane) in the structure of the YBa2Cu3O7−δ phase has been found to depend on the size of the Y2BaCuO5 inclusions and the pattern of their distribution, which in turn is defined by the initial materials. A process has been developed of the oxygenation of the thin-wall (cellular) MT-YBCO ceramics under the conditions of the controllable oxygen pressure from 0.5 kPa to 16 MPa and temperatures from 900 to 800°C. The process allows one to attain record high j c values and double the trapped magnetic field as compared to both the bulk MT-YBCO ceramics oxygenated under the same conditions and thin-wall MT-YBCO ceramics oxygenated at atmospheric pressure and optimal temperature.

Most hydrostatic pressure deformation techniques necessitate the use of a confining medium to apply the pressure. In the case of solid confinement, the embedding medium may modify the specimen stress tensor hydrostaticity. In this study, parallelepiped specimens deformed under gaseous confining pressure with the Paterson press, are embedded in cylindrical jackets. Finite element modelling shows that the pressurization of the ‘sample + jacket’ assembly generates a pre-compression stress of the sample before any deformation test. The evolution of the pre-compression stresses with the sample and jacket Young's moduli ratio, the sample and jacket yield stresses ratio and the spacing between sample and jacket, are characterized. This modelling is applied to 4H-SiC deformed in the brittle regime with the Paterson press as an example.

International audience; Pig manure is a complex mixture with excessive nutrients such as ammonium, microbial pathogens and may contain contaminants such as antibiotics. Conventional pig manure management practices caused water contamination. Sludge treatment wetland has been evaluated to determine its potential use under Mediterranean climate aiming at a parsimonious use of water and preventing water contamination, two major steps to preserve water resources in the Mediterranean Basin. Preliminary NH 4-N degradation was tested using aeration process and/or addition of commercial bacterial products. Aeration alone appeared to be sufficient to ensure nitrogen transformation of the pig manure at lab small-scale (10 L) and medium-scale (300 L). Selected plant species e.g., Carex hispida for use in the integrated constructed wetland tolerated the nitrogen content after aeration enabling their use in a treatment vertical bed.

The relevant pinning centers of Abrikosov vortices in MgB$_{2}$–based materials are oxygen-enriched Mg-B-O inclusions or nanolayers and inclusions of MgB$_{x}$ (x>4) phases. The high critical current densities, j$_{c}$, of 10$^{6}$ and 10$^{3}$A/cm$^{2}$ at 1 and 8.5 T, respectively, at 20 K can be achieved in polycrystalline materials (prepared at 2 GPa) containing a large amount of admixed oxygen. Besides, oxygen can be incorporated into the MgB$_{2}$ structure in small amounts (MgB$_{1.5}$O$_{0.5}$), which is supported by Auger studies and calculations of the DOS and the binding energy. The j$_{c}$ of melt textured YBa$_{2}$Cu$_{3}$O$_{7-δ }$ (or Y123)-based superconductors (MT-YBaCuO) depends not only on the perfectness of texture and the amount of oxygen in the Y123 structure, but also on the density of twins and micro-cracks formed during the oxygenation (due to shrinking of the c-lattice parameter). The density of twins and microcracks increases with the reduction of the distance between Y$_{2}$BaCuO$_{5}$ (Y211) inclusions in Y123. At 77 K j$_{c}$=8⋅10$^{4}$ A/cm$^{2}$ in self-field and j$_{c}$=10$^{3}$ A/cm$^{2}$ at 10 Т were found in materials oxygenated at 16 MPa for 3 days with a density of twins of 22–35 per μm (thickness of the lamellae: 45-30 nm) and a density of micro-cracks of 200–280 per mm. Pinning can occur at the points of intersection between the Y123 twin planes and the Y211 inclusions. MTYBaCuO at 77 K can trap 1.4 T (38×38×17 mm, oxygenated at 0.1 MPa for 20 days) and 0.8 T (16 mm in diameter and 10 mm thick with 0.45 mm holes oxygenated at 10 MPa for 53 h). The sensitivity of MgB$_{2}$ to magnetic field variations (flux jumps) complicates estimates of the trapped field. At 20 K 1.8 T was found for a block of 30 mm in diameter and a thickness of 7.5 mm and 1.5 T (if the magnetic field was increased at a rate of 0.1 T) for a ring with dimensions 24×18 mm and a thickness of 8 mm.

The recent observation of perfect dislocations at high stress and low temperature in silicon [J. Rabier, P. Cordier, J. L. Demenet, and H. Garem, Mater. Sci. Eng. A 309/310, 74 (2001)] in accordance with the calculations of Duesbery and Joos [M. S. Duesbery and B. Joos, Philos. Mag. A 74, 253 (1996)] has solved the apparent paradox regarding the nature of mobile dislocations in silicon under usual deformation conditions. However, although several experiments and calculations are consistent with those perfect dislocations being located in the shuffle set, little is known about the actual core structure of those dislocations which lie along unusual Peierls valleys: (112)/30°, /41°. This paper aims to review and discuss recent results related to high-stress plasticity and dislocation core structure in silicon.

Compression tests under confining pressure are performed with a Paterson press in order to deform 4H-SiC plastically below the brittle-to-ductile transition temperature. Deformation microstructure in this regime is analysed using conventional and high resolution transmission electron microscopy and is compared with literature. Leading partial dislocations with carbon core and silicon core are observed on basal plane as well as perfect dislocations out of the basal plane. Double stacking faults are evidenced in the deformed microstructure. These original observations indicate that the deformation microstructures of 4H-SiC in the brittle domain are more complex than previously reported. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Mineral Physics Institute, Stony Brooks University, Stony Brooks, NY 11794-2100, USA Received 17 September 2006, revised 18 December 2006, accepted 18 December 2006 Published online 24 May 2007 PACS 61.66.Bi, 61.72.Bb, 61.72.Lk, 62.20.-e, 62.50.+p Mechanical data have been obtained on silicon single crystal under hydrostatic pressure between room temperature and 450 °C. This temperature domain corresponds to the regime where perfect dislocations control plastic deformation. This was achieved using a D-DIA apparatus in the synchrotron beam of NSLS. Stress strain curves were deduced from X Ray diffraction and sample imaging under 5 GPa and a strain rate of 2.5 10

The oxygenation under the high 16 MPa oxygen pressure allows reducing the duration of oxygenation and in the case of thin-walled MT-YBCO ceramics (with drilled holes) leads to a decrease of the amount of macrocracks in the structure and to an increase in critical current density in the ab-planes. An increase in the twin density enhances the critical current density in the ab-planes of the Y123 textured structure of MT-YBCO. After oxygenation under different conditions the MT-YBCO ceramics produced from a mixture of Y123 with Y211 demonstrated a critical current density in magnetic fields above 2 T at 77 K higher in the ab-planes and lower in the perpendicular c-direction than the MT-YBCO produced from Y123 and Y2O3. Mechanical properties (hardness, fracture toughness, Young modulus) have been estimated for various types of MT-YBCO oxygenated under different conditions. Both traditional and thin-walled ceramics have a higher microhardness after oxygenation under high 16 MPa oxygen pressure.

International audience; A field study on the capacity of spontaneous vegetation of four motorway ponds to extract four trace metals (Cd, Cu, Zn and Pb) was carried out. High biomasses (ca. 400 g m (2) DW) of freshwater macroalgae Chara spp. were found in all ponds. However, higher biomasses (ca. 900 and 1600 g m (2) DW for aerial and root parts, respectively) were found for broadleaf cattails Typha spp. with perennial structures. Biomasses of Chara were mainly controlled by seasonal variations and water level of the ponds. Metal contents in Chara vulgaris beds were higher than those in Chara globularis and, with less than half of the biomass corresponded to the same range than those found in Typha. For the latter, the highest contents of metals were found in the root system. Sediments of the ponds were moderately contaminated and the concentrations of the four metals were very low in the water (often under detection level). Translocation factors of the contaminants from sediment to plants were very low (parts per thousand) for all species and phytoextraction of metals from the sediment seemed not to be the main effect of the spontaneous vegetation. However, this latter prevent pollutant transfers provided that the dry and crumbly Chara are collected during summer before being blown outside the pond by strong winds. (C) 2015 Elsevier B.V. All rights reserved.

International audience; Atractylis serratuloides is an abundant native spiny species that grows in the surroundings of superphosphate factories in Tunisia. This plant species is adapted to arid environments and tolerates a high level of fluoride pollution in soils. The aim of this study was to better understand the physiological mechanisms of fluoride tolerance of this species, comparing the fluoride-contaminated sites of Gabes and Skhira with the reference site of Smara. Results demonstrated the involvement of leaf element and phytometabolite balances in the in situ response of A. serrulatoides to fluoride. Calcium, sulphur and magnesium were differently distributed between the sites of Gabes and Smara in all plant organs. No specific tissue fluorine accumulation in root, stem and leaf, even in the most contaminated site at Gabes, was detected by EDAX mapping. Lower anthocyan and flavonol levels but enhanced nitrogen balance index were found in A. serrulatoides leaves from Gabes compared to the two other sites. A. serratuloides appeared as a fluoride excluder and its tolerance involved calcium interactions with fluoride. Moreover, an occurrence of dark septate endophytes and arbuscular mycorhizal fungi in root systems of A. serratuloides was reported for the first time, and these symbioses were present but low at all sites. We suggest the use of this plant species for fluoride-polluted soil stabilization.

Background, Aim and Scope Most studies of sewage sludge disposal effects on plants have focused on high metal loadings. Less attention has been paid to plant responses to trace metal loadings below the recommended limit values. Materials and Methods: Here, a lysimetric experiment was conducted to assess the uptake, distribution and binding of trace metals by metal-induced, sulfhydryl-rich peptides (phytochelatins) in colza (Brassica napus, v. Jaguar) grown on a clayey, silty soil amended with a sewage sludge compost containing trace metal contents far below the recommended limit values established by French legislation. Chemical fractionation of unamended and sludge-amended soils was performed using a sequential extraction technique. Results: Copper concentrations in plant tissues were not affected by compost disposal. Its application at a single rate equivalent to 30 t/ha stimulated the growth of plants. Lead was not detectable in the plant material (< 1 mg g-1 dry wt.). Plants grown on the amended soil accumulated significantly more zinc than control plants. These phytochelatin complexes detected in leaves had a lower molecular weight than those extracted from roots. Those extracted from roots were composed of one type of phytochelatins (PCs) such as in leaves or a mixture of glutathione, PC2 and PC4. In comparison with control plants, sewage sludge compost application caused the synthesis of longer chain PCs in roots and in leaves. Furthermore, in comparison with control roots, glutathione and phytochelatin mixtures of higher molecular weight were detected in roots produced on the amended soil, whereas no significant increase in \total\ Cu and Zn content was observed in these organs after sludge application. Discussion: Compost application induces a significant increase in the proportion of the most labile forms of zinc and especially its pH 4.7 acid-soluble forms and, as a consequence, a higher accumulation of zinc in plants. Effects of copper are limited due to its strong affinity for humic substances and lead does not seem to be transported in any organ of plants. The presence of phytochelatins, even in plants grown on the unamended soil, proved the ability of colza to synthesize them in the presence of zinc and copper. Conclusions: These primary results seem to prove, on one hand, ability of colza (Brassica napus, v. Jaguar) to synthesize phytochelatins as well as in roots, in leaves and, on the other hand, the sensitivity of the PC induction as suggested by their identification in plants grown on the control soil. Synthesis of longer chain PCs in roots and in leaves, and formation of glutathione and phytochelatin mixtures in roots, are plant responses to sewage sludge compost application. Recommendations and Perspectives: Phytochelatin analysis is thus supposedly able to be one of the bioindicators that may be used as an ecotoxicological risk assessment of wastes. Due to its ability to synthesize phytochelatins, colza could be chosen as a plant test. Phytochelatin analysis could also be limited to roots (more sensitive than leaves). However, further experiments are needed. Quantitative analysis of phytochelatins had not been carried out due to insufficient amounts of pure phytochelatin standards, that had allow us to better study relationships between trace metal amounts to vegetal response.

The deformation microstructure of single crystals of 4H-SiC resulting from microindentations on a prismatic surface was investigated by TEM. Indentations were performed at 400 and 675°C, i.e. below the brittle to ductile transition temperature of 4H-SiC (temperature close to 1100°C). TEM analysis reveals dissociated dislocations as well as extended stacking faults in the basal plane. In addition, perfect edge dislocations are observed on prismatic planes. From the observations, it is assumed that perfect dislocations are nucleated in the prismatic plane and cross-slip on the basal one where they dissociate.

Numerous original alkaloids are present in tubers of Arisarum vulgare Targ. a species belonging to the Araceae family known in Morocco for its toxicity. Some previous works deal with the activity of these natural compounds as R-irniine. As the enantioselective total synthesis of irniine has been realised, the R- and S-forms were obtained and this last one could be tested. Thus, a study of the cytotoxicity and the electrophysiological activity of S-irniine was carried out on human MRC-5 fibroblasts. A cytotoxic effect of S-irniine at 40 microg/mL was detected on MRC-5 fibroblasts. An electrophysiological study was also carried out on the MRC-5 cells by using the patch-clamp technique and no effect of this compound at this concentration on the outward potassium current of MRC-5 fibroblasts was observed. Thus, this study showed, as it was for R-irniine, that the cytotoxicity of S-irniine was not explained by an effect on the potassium currents.

Melt-textured YBa2Cu3O7 samples were deformed under high pressure–high temperature (HP–HT) conditions (P = 2 GPa, T = 900 and 800°C, t = 15 min). During the HP–HT treatment, samples were in contact with annealed zirconia, preventing oxygen loss, in such a way that the orthorhombic superconductor phase was preserved at the end of the experiment. The deformed microstructure, investigated by transmitted electron microscopy, exhibited original features characterized by a very low twin density, a memory effect on the dislocations shape and a non-classical faulted loops distribution in the matrix. A mechanism, based on the interaction between twin and gliding dislocations, is proposed to explain the nucleation of these aligned loops.

Intergrowths, stacking faults and dislocations have been investigated by transmission electron microscopy in (Hg, Re)Ba2Ca2Cu3O8+δ and HgBa2CaCu2O6+δ bulk superconductors. The stacking fault vectors and the Burgers vectors of partial edge dislocations associated with the nucleation or the annihilation of [Ca–CuO2] bilayers in the unit cells of both compounds are derived by different methods. We discuss the influence of uniaxial stresses on intergrowth propagation and also mechanisms yielding strain relaxation around intergrowths. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Dislocations in silicon are nucleated under high stresses as perfect ones in the shuffle set. It is shown that the same nucleation mechanism operates in hexagonal 4H-polytype SiC but, in contrast to silicon, perfect-shuffle configurations are unstable and transform by cross-slip into glide set dislocations.

Icosahedral Al–Pd–Mn quasicrystalline alloys are known to be extremely brittle at low and intermediate temperatures when deformed with conventional tests. Using specific deformation conditions, such as high confining pressure techniques, allowed plastic deformation of this non-periodic structure at temperatures in the brittle domain. Surprisingly, low temperature deformation microstructures revealed the presence of dislocations, whose motion essentially implicates climb mechanisms. The aim of this study is to use a shear experiment technique, specially designed to favour glide processes, in order to check if glide may occur solely, without any climb component. The results confirm the difficulty to promote pure glide processes and support the idea that both glide and climb are activated.

Transmission electron microscopy observations of melt-textured YBa2Cu3O7–Y2BaCuO5 composites deformed under uniaxial stress and a superposed gaseous confining pressure reveal the activation of a novel YBa2Cu4O8-type stacking fault source. This mechanism operates as a partial Frank Read source leading to small diameter (100–300 nm) loops. Jcab(T) dependences reveal a temperature dependent enhancement which is maximum at low temperatures, i.e., 45% at 5 K. A fit of Jcab(T) to a model that considers two contributions to Jc, namely correlated disorder and weak pinning, reveals that only the weak pinning contribution associated with the newly generated in-plane dislocation substructure is enhanced after deformation.

The essential oil of the aerial parts of Triumfetta rhomboidea was analysed by GC and GC-MS and assayed for its antibacterial and antifungal activities. The main constituents identified were trans-β-caryophyllene (22.4%),kessane (14%) and caryophyllene oxide (13%). The antimicrobial tests showed a mild activity against Escherichia coli and Enterococcus hirae.

Microstructures of Al–Pd–Mn quasicrystalline specimens deformed at low temperatures were studied by transmission electron microscopy. Analysis of the corresponding microstructures indicates that plastic deformation takes place by dislocation glide and climb. Faulted dislocation loops were observed. Tentative explanations are given to explain nucleation and growth of these dislocation loops.

The dislocation substructures of silicon deformed under hydrostatic pressure at room temperature in various deformation conditions have been characterized by transmission electron microscopy. This confirms the occurrence of deformation mechanisms by perfect dislocations for high-stress conditions. Dislocation line instabilities are found being consistent with a deep Peierls potential along 〈123〉 orientations. The nature of the core of those perfect dislocations is discussed in relation with these observations.