Unconventional ferromagnetic and spin-glass states of the reentrant spin glass Fe0.7Al0.3

Spin excitations of single crystal Fe0.7Al0.3 were investigated over a wide range in energy and reciprocal space with inelastic neutron scattering. In the ferromagnetic phase, propagating spin wave modes become paramagnon-like diffusive modes beyond a critical wave vector q0, indicating substantial disorder in the long-range ordered state. In the spin glass phase, spin dynamics is strongly q-dependent, suggesting remnant short-range spin correlations. Quantitative model for S(energy,q) in the ``ferromagnetic'' phase is determined.Comment: 4 pages, 5 figure

DYNAMIQUE EROSIVE ACTUELLE ET TRANSFERTS FLUVIATILES DANS L'OUEST DU BASSIN DE PARIS. Exemple de bassins versants littoraux en Haute Normandie : le Dun, la Ganzeville et l'Yères.

Applied to small coastal river basins of the Western Paris Basin, the interest of this work is to present an integrated approach of the erosion dynamics at the scale of the river basin, from measurements of soil erodibility to high frequency monitoring of transfers in rivers. The objective is to quantify accurately river sediment yields, to identify factors controlling the erosion dynamics and to propose an estimation of continental sedimentary contributions to the English Channel. The obtained results underline that, despite of limonous soils highly erodible and high erosion rates measured from agricultural catchments, the rivers studied have some of the lowest values of sediment yield on a global scale (10, 1 t km-2 an-1 for the Yères River, 1, 3 t km-2 an-1 for the Dun River, 6, 6 t km-2 an-1 for the Ganzeville River). The comparison of these data with those of 214 rivers around the world (including the Somme and the Seine Rivers) confirms the influence of global factors controlling the erosion dynamics: basin area, low relief and moderate runoff. Regionally, this last factor is forced by a karstic hydrological functioning that is involved in the deficit balance of water discharges but also in the relief landscape (surface storage of soils erosion products) and in a fine materials storage in the subsurface karstic network. Within the studied river basins, the contribution of groundwater to the surface flow was established about 90 %. Concerning the sedimentary contributions to the English Channel, the extrapolation of these river sediments yields to all Norman coastal rivers (Seine-Maritime) gives a regional river sediment delivery of 48 500 t yr-1. This sediment delivery also appear to be low on global and regional scales - where the average sediment yield of the Seine River reaches 715 000 t.an-1 at Poses, the upstream limit in the estuary.La compréhension des transferts sédimentaires depuis les zones " source " jusqu'aux zones de dépôt des sédiments constitue un enjeu majeur pour la lutte contre l'érosion des sols et la qualité des eaux. Portant sur de petits bassins versants côtiers de l'Ouest du bassin parisien, l'intérêt de ce travail est de présenter une démarche intégrée de la dynamique érosive à l'échelle du bassin versant, depuis l'analyse de la stabilité structurale des sols jusqu'au suivi haute fréquence des transferts de matières en rivière. L'objectif est d'identifier les facteurs contrôlant le ruissellement et l'érosion sur ces sites et de proposer une estimation des apports fluviatiles de matières en suspension (MES) à la Manche orientale. Les résultats obtenus soulignent que malgré des sols limoneux peu structurés générant des taux d'érosion à la parcelle importants, les bilans d'érosion enregistrés en rivière sont parmi les plus faibles du monde (10,1 t.km-2.an-1 pour le bassin de l'Yères, 1,3 t.km-2.an-1 pour le bassin du Dun et 6,6 t.km-2.an-1 pour le bassin de la Ganzeville). La comparaison de ces données avec celles de 214 bassins versants mondiaux montre que ces faibles bilans sont expliqués par la taille des bassins étudiés (< 1000 km2), le relief modéré et le faible débit spécifique. Régionalement, ce dernier facteur est contraint par un fonctionnement hydrologique karstique, qui est à l'origine non seulement du déficit de la balance des écoulements de surface mais aussi d'un stockage intrakarstique de matériaux fins issus de l'érosion des sols. Les résultats mettent en évidence des échanges nappe-rivière très importants sur les sites d'étude : la contribution des eaux souterraines au débit de surface est de l'ordre de 90 %. Concernant les apports fluviatiles de MES à la Manche orientale, l'extrapolation des bilans d'érosion obtenus à l'ensemble des fleuves côtiers du littoral haut-normand conduit à une estimation du flux exporté à la mer de 48 500 t.an-1. Issu de l'érosion des bassins versants côtiers, ce flux de MES apparait très faible tant à l'échelle mondiale que régionale où le flux de MES de la Seine atteint en moyenne 715 000 t.an-1 à Poses en amont de l'estuaire

Traité de la conjugaison des verbes... par E.-A. Lequien,... 4e édition...

Contient une table des matièresAvec mode text

Cacographie rangée dans un nouvel ordre, ou Exercices sur l'orthographe, la syntaxe et la ponctuation ; par E.-A. Lequien,... 6e édition...

Avec mode text

Corrosion influence on the evaporation of sessile droplet

International audienc

Oscillatory interlayer exchange and magnetoresistance in Fe/Cu multilayers

We have studied the magnetic and magnetotransport properties of Fe/Cu mu1tilayers prepared by sputtering. We find oscillations of the inter1ayer coupling as a function of the Cu thickness with the same long period as in Co/Cu multilayers (around 12.5 Á). The most striking result is that the oscillations in Fe/Cu and Co/Cu have almost exactly opposite phases. A large magnetoresistance of the spin-valve type is observed in the half periods with antiferromagnetic interlayer exchange. However, the magnetoresistance in Fe/Cu is definitely smaller than in Co/Cu

Apports sédimentaires continentaux actuels aux plages et à la mer de la Manche. Exemple des falaises et des rivières littorales de l'Ouest du Bassin de Paris

International audienceA qualitative and quantitative understanding of the transport of sediment from the continents to the oceans is essential for environmental and natural resource management, particularly when it is associated with rock falls, slumping, landslides, contaminant transport, or flooding. The study presented here quantifies and characterizes sediment transport from the northwest Paris Basin to the English Channel by analyzing the two processes providing the solid material: the retreat of coastal cliffs and the erosion of coastal watersheds. For the analysis, we combine two approaches, the photogrammetric analysis of retreating cliff faces and the high-frequency measurement of river discharge and suspended sediment concentration, complemented by a grain-size analysis of the sediment sources. The results indicate that the sediment contribution from cliff erosion (1 million m3/yr producing 2 million t/yr of sediment) greatly exceeds that from the coastal rivers (43 000 t/yr). The cliff erosion input exceeds the fluvial input at the event scale as well, with cliff erosion contributing, for a single event, 200 to 2000 t/day (100 to 1000 m3) (for the most frequent collapse), and rivers contributing 4 to 6 t/day (for a flood). The influx from rivers, however, should not be overlooked, as the 4 to 6 t/day contributed is carried by 7000 to 160 000 m3/day of water, sometimes causing natural disasters such as floods and mudflows. The solids resulting from cliff erosion are composed of flint (462 500 t) and fine silicates (mostly silt and clay) derived from the cliff-forming chalk as well as from overlying formations (clay-with-flints and loess), whereas the fluvial inputs consist almost entirely of silt.L'etude qualitative et quantitative des transferts sédimentaires du continent à la mer constitue un enjue majeur pour la gestion des milieux et de leurs ressources naturelles, notamment lorsque ces transferts s'accompagnent d'éboulements, de glissements de terrain, de transferts de polluants, d'inondations, de coulées de boue... Notre étude, qui s'inscrit dans cette thématique, a consisté à quantifier et à caractériser les transferts sédimentaires du Nord-Ouest du Bassin de Paris vers la Manche en prenant en compte les deux sources impliquées dans ces transferts: recul des falaises littorales et érosion des bassins versants littoraux. Cette recherche s'appuie principalement sur la combinaison de deux approches originales, l'analyse photogrammétrique du recul des falaises et la mesure haute fréquence du débit et de la charge solide en suspension dans l'eau, complétées par une caractérisation granulométrique des sources. Les résultats ont montré que l'apport annuel des rivières littorales est plus faible que celui des falaises, avec respectivement 43 000 t/an et 1 million de m3/an, soit 2 millions t/an. A l'échelle d'un événement, l'apport par les rivières est également plus faible que celui des falaises, avec respectivement 4 à 6 t/jour pour une crue et de 100 à 1000 m3, soit 200 à 2 000 t, pour les éboulements les plus fréquents. Cependant, les apports solides par les rivières ne doivent pas être négligés, notamment lorsqu'il s'agit des crues, car ces 4 à 6 t/jour sont transférées par 7000 à 160 000 m3/jour d'eau, pouvant ainsi occasionner de véritables catastrophes (crue turbide, inondation...). Enfin, les apports par les falaises sont composés de silex (462 500 t) et d'une fraction silicatée fine (sous forme majoritairement de silts et d'argiles) provenant des craies mais également des formations superficielles superposées (altérites à silex et loess), tandis que les apports par les rivières sont constitués principalement de silts

Magnetic superparamagnetic-like microparticles for cancer cells destruction

International audienceTo improve cancer treatment with reduced side effects, several techniques are currently under investigation, such as targeted drug delivery or hyperthermia . This work is related to the study of a newly discovered technique: the triggering of cancer cell apoptosis by mechanical vibrations of magnetic microparticles attached to the cancer cells membrane . This method, which targets only diseased cells, was firstly demonstrated by Kim et al in 2010. The method consists in specifically attaching magnetic anisotropic particles to cancer cells membrane and then applying a weak alternative magnetic field . The induced particles vibrations generate a stress on the cells membrane. A chemical chain reaction is then triggered, which causes the reactivation of the apoptosis of cancer cells . The triggering of the apoptosis of human renal cancer cells was also demonstrated by SPINTEC. The magnetic particles used for this purpose have to respect a few specifications: they must have a sufficiently large volume, they must be anisotropic so that they can be actuated by a magnetic field rather than a gradient of magnetic field, and they have to be superparamagnetic-like in order to avoid any aggregation in solution . Two types of magnetic particles fulfilling these specifications were developed in this work: permalloy particles presenting a vortex structure and magnetite particles presenting a polycrystalline random anisotropy configuration

Small-angle X-ray scattering at the european synchrotron radiation facility

No abstract availabl

Characterization of an aluminum conductor steel reinforced (ACSR) after 60 years of operation

International audienceAn aluminum conductor steel reinforced (ACSR) extracted from an overhead power line operated in Northern France during more than 60 years was characterized together with a more recent equivalent conductor. Visual inspection, local observation and chemical analysis by Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) as well as Raman spectroscopy were used to characterize the microstructure of the strands and to evidence signs of corrosion or potential degradation. Analysis of the grease was done by Fourier Transform InfraRed Spectroscopy (FTIR). The mechanical properties of the strands were evaluated by constant strain rate tensile test at ambient temperature. Hardness was measured as well. Partial oxidation of the steel galvanization layer, degradation of the grease – especially oxidation due to ageing – and atmospheric corrosion pits on the external layer of aluminum strands were evidenced. The mechanical properties of the galvanized steel strands were still in agreement with the requirements of the standards edited in 1955 contrarily to the mechanical properties of the external layer aluminum strands, indicating a potential deleterious effect of the corrosion pits. The tensile strength of the conductor estimated from the mechanical properties of its constitutive strands was slightly higher than the requirements of the standards edited in 1955 and slightly lower than the more demanding requirements of recent standard