M-SrFe12O19 and ferrihydrite-like ultrathin nanoplatelets as building blocks for permanent magnets: HAADF-STEM study and magnetic properties

Mixtures of M-type strontium hexaferrite (M-SrFe12O19) and ferrihydrite-like particles were prepared by a microwave-assisted hydrothermal process at 200 °C with heating rates in the range 40–50 °C min-1. The particles exhibited a platelet shape with a diameter comprised between 20 and 200 nm and a thickness between 2 and 5 nm. HAADF-STEM observations and EDS analysis were carried out for a better understanding of nucleation and growth process. EDS showed that most of the particles contained Sr and HAADF-STEM revealed that very thin particles with a hexaferrite core extending over less than a unit cell and with surface disorder crystallized along with well crystallized hexaferrite and defect free ferrihydrite particles. The symmetric multilayer structures (SRS) of the ultrathin particles suggested that the nucleation step of the hexaferrite particles involved clusters containing Sr atoms. In comparison with the M-SrFe12O19 micrometer sized platelets prepared with heating rate of 25 °C min-1, the mixtures of ultrathin hexaferrite- and ferrihydrite-like particles combined after annealing a higher coercivity reaching 465 kA m-1 thanks to the smaller initial particle size and a high magnetization reaching 65 A m2 kg-1 thanks to a limited amount of hematite

Geotraceability and life cycle assessment in environmental life cycle management: towards sustainability.

Sustainability is an emerging concept in product chains and integrates environmental, social, and economic aspects during the product's life cycle. Recently, the demand for environmental quality has required information about the products' life cycle. Life Cycle Assessment (LCA) includes the inventory analysis, where the products´life cycle are systematized, and the Life Cycle Impact Assessment, when the environmental impacts potentials are calculated. A powerful tool to describe the history, use, and lication of a product in called geotraceability..

Very-high-resolution mapping of river-immersed topography by remote sensing

Remote sensing has been used to map river bathymetry for several decades. Non-contact methods are necessary in several cases: inaccessible rivers, large-scale depth mapping, very shallow rivers. The remote sensing techniques used for river bathymetry are reviewed. Frequently, these techniques have been developed for marine environment and have then been transposed to riverine environments. These techniques can be divided into two types: active remote sensing, such as ground penetrating radar and bathymetric lidar; or passive remote sensing, such as through-water photogrammetry and radiometric models. This last technique which consists of finding a logarithmic relationship between river depth and image values appears to be the most used. Fewer references exist for the other techniques, but lidar is an emerging technique. For each depth measurement method, we detail the physical principles and then a review of the results obtained in the field. This review shows a lack of data for very shallow rivers, where a very high spatial resolution is needed. Moreover, the cost related to aerial image acquisition is often huge. Hence we propose an application of two techniques, radiometric models and through-water photogrammetry, with very high-resolution passive optical imagery, light platforms, and off-the-shelf cameras. We show that, in the case of the radiometric models, measurement is possible with a spatial filtering of about 1 m and a homogeneous river bottom. In contrast, with through-water photogrammetry, fine ground resolution and bottom textures are necessary

Les systèmes cadastraux: des instruments de base pour la gouvernance des territoires en Amérique latine ?

Dans la dernière décennie, les systèmes cadastraux ont fait l’objet d’une modernisation conceptuelle importante et sont devenus, avec les progrès réalisés dans le secteur de la géomatique, de véritables infrastructures informationnelles de gouvernance territoriale. En effet, l’information cadastrale est dorénavant utilisée à des fins aussi diverses que, la planification de l’aménagement, le contrôle de l’utilisation du sol, la prévention des risques naturels et le développement durable. Le cadastre du Québec n’échappe pas à ces grandes tendances. Il fait actuellement l’objet d’une importante réforme visant à améliorer le système de protection des droits fonciers, tout en favorisant son utilisation polyvalente et la création d’applications à valeur ajoutée. Malgré certaines difficultés inhérentes à la réalisation de projets cadastraux d’une telle ampleur, l’expérience québécoise peut être qualifiée de succès. Certains pays tentent de s’en inspirer pour élaborer et réaliser leur propre réforme cadastrale. C’est le cas en Amérique latine où le cadastre constitue une composante importante de projets visant à renforcer les mécanismes d’administration des terres, les modes de tenure foncière et la sécurisation des droits immobiliers. De plus, de tels projets s’inscrivent souvent dans le cadre élargi des politiques de décentralisation des pouvoirs, de réduction de la pauvreté, d’égalité des genres et de renforcement des gouvernements locaux. Cependant, on constate de plus en plus que les projets cadastraux ne permettent ni d’atteindre les objectifs fixés au préalable, ni de mettre en œuvre les nombreuses possibilités présentées par les concepts modernes de systèmes cadastraux. En effet, il semble y avoir un fossé entre les concepts cadastraux et la réalité des projets de cadastre. Afin d’examiner ce problème et de tenter d’en identifier les caractéristiques, cet article propose une comparaison entre le cadastre du Québec et des problématiques cadastrales du Honduras et du Mexique, ayant faits l’objet de recherches récentes. In the last decade, cadastral systems have been the object of an important conceptual upgrading and became, with the progress realized in the geomatics sector, spatial data infrastructures for land governance. Nowadays, cadastral information is used in purposes so diverse as land use planning and control, natural risks mitigation and sustainable development. The Quebec cadastre does not escape these trends. A major cadastral reform is underway to improve the system of land right protection, while facilitating its multi-purpose uses and the creation of value-added applications. In spite of certain difficulties inherent to the realization of cadastral projects of such a scale, the Quebec experience can be qualified as success. Certain countries take this cadastral reform as an example for their own project. It is the case in Latin America where cadastre constitutes an important constituent of projects aiming at strengthening the mechanisms of land administration and tenure, and property rights security. Furthermore, such projects are often realized in the larger frame of powers decentralization policy, poverty reduction, gender equality, and local empowerment. However, we notice more and more that the cadastral projects do not allow to reach the objectives fixed beforehand and to implement the numerous possibilities presented by the modern concepts of cadastral systems. Indeed, a gap seems to exist between the cadastral concepts and the reality of cadastral projects. To examine this problem and try to identify its characteristics, this article proposes a comparison between the cadastre of Quebec and cadastral problems of Honduras and Mexico, which were the object of recent studies

Characterization of cadmium proteinuria in man and rat.

In workers chronically exposed to cadmium and without signs of renal insufficiency, plasma proteins with molecular weight ranging from 11,800 to 450,000 are excreted in greater amount in urine. Increased urinary excretion of low and high molecular weight proteins can occur independently. Because of its greater stability in urine and provided a sensitive immunological technique is used, the determination of retinol-binding protein is a more practical and reliable test of proximal tubular function than beta 2-microglobulin. The evaluation of renal function of workers removed from cadmium exposure indicates that cadmium-induced renal lesions, albeit of slow progression, are not reversible when exposures ceases. In workers chronically exposed to cadmium or removed from cadmium exposure, metallothionein in urine is directly correlated with cadmium in urine but not with cadmium in blood or years of cadmium exposure. The association between cadmium in urine and metallothionein in urine is independent of the status of renal function and the intensity of current exposure to cadmium. Whereas the repeated IP injection of high doses of cadmium to rat gives rise to a mixed or tubular type proteinuria, the prolonged oral administration of cadmium results mainly in the development of a glomerular type proteinuria. The former is usually reversible after cessation of treatment whereas the latter is not. Circulating antiglomerular basement membrane antibodies have been found in man and in rat chronically exposed to cadmium. The pathogenic significance of this finding deserves further investigation

Impact behavior of injected PP/nanoclay parts

This work attempts to contribute to bridge the gap between scientific challenges and industrial stakes regarding PP/nanoclay composites. Pieces of nanocomposites were obtained by direct injection of commercial PP mixed with a commercial MB of PP with 50% of organoclay, with a double-gated hot runner mould, which produced mouldings with a weld line. The moulding microstructure was assessed by POM and XRD, while the distribution and exfoliation grade of clay was evaluated by TEM and XRD. The typical skin-core structure was found, with a skin thickness wider in bulk than in weld line zones. Regarding clay platelets mostly intercalated structures were seen. The impact properties at room temperature were assessed by means of tensile and biaxial tests. Properties were monitored at different sites of the mouldings. At the weld line zone less energy was consumed under tensile conditions and exhibited higher apparent impact toughness under biaxial conditions than the bulk zone. Visual inspection of biaxially impacted samples showed that the orientation of polymer molecules and clay platelets induced by melt flow prevailed, and the weld line was not the determinant of the toughness of the mouldings. An optimum in impact performance was found for moulding with 3% of clay, since at larger clay contents platelets agglomerated and acted as stress raisers

Uni- and biaxial impact behavior of double-gated nanoclay-reinforced polypropylene injection moldings

Polypopylene/nanoclay three-dimensional parts were produced without intermediate steps by direct injection molding to explore the influence of flow features and nanoclay incorporation in their impact performance. The nanocomposite was obtained by direct compounding of commercial PP with nanoclay masterbatch. The as-molded morphology was analyzed by X-ray and TEM analyses in terms of skin-core structure and nanoclay particle dispersion. The nanoclay particles induced the reduction of b-form spherulites, a known toughener. The impact behavior was assessed in tensile and biaxial modes. The PP nanocomposite molding toughness was practically unaffected by the processing melt temperature and flow rate. Conversely the nanoclay presence is influent in the impact performance. Under biaxial stress impact, the regions close to weld lines are tougher than the bulk and the fracture develops with main crack paths along the flow direction and the weld line. Cracking along the weld line results from less macromolecular interpenetration and chain entanglement, and unfavorable nanoparticle orientation. It seems that a failure mechanism which involves nanoclay delamination and multiple matrix crazing explains the toughening of PP in the directions where the nanoparticle orientation with respect to loading is adequate.Contract grant sponsors: CONICET, ANPCyT from Argentina, MINCyT (Argentina) - FCT (Portugal), Universities Nacional de Mar del Plata and Minho