200 research outputs found

    Investigation on the Mechanism of Electrocodeposition and the Structure-Properties Correlation of Nickel Nanocomposites

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    There is an increasing interest in nanostructured and nanocomposite surface finishings for automotive and aerospace applications. The widespread applicability of these novel materials is based on their unique mechanical, physical, and chemical properties. An advantageous production method is the electrocodeposition (ECD) process from metal plating baths containing dispersed nanoparticles. By using this technique, a broad range of substrate sizes and shapes can be coated cost-effectively. However, the prediction of the amount as well the distribution of nanoparticles within the metal film fails frequently. There is no complete understanding of the particle incorporation mechanism. The goal of this research was to improve the fundamental understanding of the ECD mechanism. In order to identify the forces affecting the codeposition behavior of nanoparticles in a metal matrix, the effects of a variety of interrelated process parameters on the composite film formation have been investigated systematically. Nanocomposites containing metal and metal oxide nanoparticles in a nickel matrix have been prepared by means of ECD from two different types of nickel plating baths, an acidic sulfamate (pH 4.3) and an alkaline pyrophosphate bath (pH 9.5). The effect of deposition conditions on the ECD process was investigated utilizing two electrode configurations, viz. a parallel plate electrode (PPE) and impinging jet electrode (IJE) and different deposition techniques, viz. direct current (DC) deposition, both pulse plating (PP) and pulse-reverse plating (PRP). The surface charge and sedimentation behavior of the nanoparticles in these electrolytes were characterized by zeta potential and stability measurements. The surface charge, hydrodynamic diameter and colloidal stability of the nanoparticles in the nickel electrolytes were mainly affected by the composition and pH of the bath. The particles tend to form agglomerates in both nickel baths. Smaller agglomerates and an improved colloidal stability occurred in the case of the alkaline bath. Composites with a maximum particle content of either ~3.6 vol-% of 13 nm Al2O3 or ~10.4 vol-% of 21 nm TiO2 were obtained using a parallel plate electrode and DC deposition conditions. Both jet plating as well as pulse plating resulted in a distinct increase of the particle codeposition. A maximum incorporation of ~12 vol-% of 50 nm Al2O3 particles in a nickel matrix was achieved using an unsubmerged IJE system, while PP and PRP resulted in composites with particle contents up to 11 vol-% of 13 nm Al2O3. The particle incorporation increased with the particle content of the electrolyte for all deposition conditions studied. A beneficial effect on the amount of codeposited particles was found with decreasing average current density. The Al2O3 and TiO2 particles were found to be negatively charged in the alkaline pyrophosphate bath, and positively charged in the acidic sulfamate bath. It could be shown that negatively charged particles codeposited preferentially within the nickel matrix. The effect of PP and PRP conditions, e.g. pulse frequency, duty cycle and value of the peak current density, on the ECD of Ni-Al2O3 composites was studied using rectangular current pulses in the order of milliseconds. In general, low duty cycles and high pulse frequencies resulted in an enhanced particle codeposition. Using the unsubmerged IJE system, the effects of jet flow rate, particle loading and current density on the particle incorporation were studied. Referring to the experimental results from the ECD of 50 nm alumina with nickel using an IJE system, a kinetic model was developed. Therefore, the particle flux to the electrode was derived from an analysis of the total force acting on the particle in front of the electrode. The model took into account the convective diffusion of particles to the electrode surface, and the effect of gravitational and buoyancy forces on the particle flux. The gravitational force was found to be important for the ECD of 300 nm particles, but not for 50 nm particles. The effect of an external magnetic field on the ECD of Co or Fe3O4 nanoparticles in a nickel matrix has been studied for different current densities, particle contents of the electrolyte and magnetic flux density. The particle incorporation showed a distinct dependency on the orientation of an externally applied magnetic field. While the particle incorporation increased in a perpendicular field (perpendicular with regard to the electrode surface), it decreased in a parallel orientation. The influence of the magnetic field on the ECD of magnetic nanoparticles with nickel was explained by the interplay of Lorentz force and magnetophoretic force. The structure and the properties of the nickel matrix were significantly altered due to the codeposition of nanoparticles. The pure nickel deposits from the sulfamate bath exhibited a strong <100> texture, and those from the pyrophosphate bath a strong <110> preferred orientation. With increasing plating current density and particle incorporation, a variation in the crystallite size and a loss of texture was observed. High resolution TEM imaging proved a complete embedding of nanoparticles by the nickel matrix without any voids. In the case of both nickel baths, the Vickers microhardness showed a tendency to increase with the amount of particle incorporation. The enhanced hardness of the composite films was associated with modifications in the microstructure of the nickel matrix as well as with the nanoparticle incorporation. The wear resistance as examined by linear abrasion test increased with decreasing current density and due to the particle incorporation. Furthermore, the incorporation of magnetic nanoparticles resulted in a distinct increase of the magnetic hardness of the nickel matrix

    Linking Early Warning Systems with Rapid Mapping - Procedure for pre-tasking of satellites for disaster impact mapping

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    This is a technical document describing the step-by-step procedure for pre-tasking of satellites for disaster impact mapping in the frame of the Copernicus Emergency Management Service (CEMS). Pre-tasking is done following alerts for upcoming disasters issued by early warning systems (in this case by the European Flood Awareness System) which are either operated under CEMS or under other frameworks. Disaster impact mapping is performed under Rapid Mapping, the 24/7/365 on-demand service of CEMS. The procedure has been integrated into the standard operating procedures of the Emergency Response Coordination Center of DG ECHO.JRC.E.1-Disaster Risk Managemen

    The benefit of continental flood early warning systems to reduce the impact of flood disasters

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    Flooding is a natural phenomenon, an intrinsic part of the natural cycle that serves important ecological functions. However, in highly anthropogenic-developed landscapes they cause serious consequences for human lives, societies in general, and their economy. Therefore comprehensive disaster risk reduction policies have been promoted in the last decade including actions on the development of early warning systems at local as well as regional scale. This report provides a brief global overview on the occurrences and damages resulting from riverine floods over the past decades. The first part of the report then summarises European policies put in place to deal with flooding in the different phases of the disaster management cycle addressing the prevention, preparedness, response, and recovery phase. This is followed by a description of the development of flood early warning capabilities at European scale, how such a system fits into the responsibility chain between national services and EU civil protection and what the potential financial benefit of flood early warning systems in Europe amounts to. The second part of the report addresses the gaps in flood early warning systems in Africa and presents a description of the African Flood Forecasting System (AFFS), which has been built in analogy to EFAS, but which is still in experimental stageJRC.H.7-Climate Risk Managemen

    Current water resources in Europe and Africa - Matching water supply and water demand

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    Ensuring good quality water in sufficient quantities for all legitimate uses is a major policy aim of the European Commission, and the main aim of the Blueprint to Safeguard Europe's Water, which will be launched in 2012. The Blueprint is the EU policy response to emerging challenges in the field of water. It is within this policy framework that JRC carries out research on hydrological simulation modelling, aiming to provide scientific assessments of general available water resources and floods, droughts and water scarcity. The main aim of the work is to assess current and future water availability versus current and future water demands from different economic sectors. Before future challenges can be addressed, a thorough analysis of current water resources is needed. The scope of this study is an analysis of current water resources in Europe and Africa, and matching water supply and water demand from various sectors. Several attempts already have been made to assess European, African and global water resources. Recently, Haddeland et al. (2011) produced a multimodel estimate of the global terrestrial water balance at 0.5o spatial resolution. This has been achieved within the Global Water Availability Assessment (GWAVA), developed in the context of the EU-funded WATCH project (https://gateway.ceh.ac.uk ). Within another EU-funded project GLOWASIS (Global Water Scarcity Information System), Utrecht University and Deltares develop a global water scarcity map also at 0.5o spatial resolution, to be finished Dec 2012 (http://glowasis.eu ). First results are published in Van Beek et al (2011). JRC is partner in this project to benchmark the global product with the higher resolution European and African assessments. A further study was conducted by Hoekstra and Mekonnen (2011), assessing global water scarcity for the world’s major river basins. Other available information on global water resources are available from: • FAO, Aquastat portal http://www.fao.org/nr/water/aquastat/globalmaps/index.stm • UNEP: http://maps.grida.no/go/graphic/freshwater-availability-groundwater-and-river-flow • Cleaningwater: http://cleaningwater.se/whats-new/geographical-distribution • IWMI Institute: http://www.iwmi.cgiar.org/WAtlas/Default.aspx • World Resources Institute: http://earthtrends.wri.org/maps_spatial/maps_detail_static.php?map_select=265&theme=4 • Monde diplomatique: http://www.monde-diplomatique.fr/cartes/disponibiliteeau • GRID-Arendal (Africa): http://www.grida.no/publications/vg/africa/ • EEA (Europe): http://www.eea.europa.eu/data-and-maps/figures/annual-water-availability-per-capita-by-country-2001 In general however, the analysis done in the products described above is done at national scales, at relatively coarse spatial resolution (0.5o), and using water demand data from the year 2000 or before, because more recent data are not yet available. The scope of the study presented here, is to carry out an higher spatial resolution analysis for Europe (5 km ~ 0.05o) and Africa (0.1o), using a daily timescale for modelling, and using for Europe new JRC analysis of water uses for irrigation, livestock, industry and energy, and domestic purposes. The analysis is carried out using the JRC LISFLOOD hydrological simulation model, supported by several other available models (EPIC, LUMP).JRC.H-Institute for Environment and Sustainability (Ispra

    Detection of Viral Infection and Bacterial Coinfection and Superinfection in Coronavirus Disease 2019 Patients Presenting to the Emergency Department Using the 29-mRNA Host Response Classifier IMX-BVN-3: A Multicenter Study.

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    Background Identification of bacterial coinfection in patients with coronavirus disease 2019 (COVID-19) facilitates appropriate initiation or withholding of antibiotics. The Inflammatix Bacterial Viral Noninfected (IMX-BVN) classifier determines the likelihood of bacterial and viral infections. In a multicenter study, we investigated whether IMX-BVN version 3 (IMX-BVN-3) identifies patients with COVID-19 and bacterial coinfections or superinfections. Methods Patients with polymerase chain reaction-confirmed COVID-19 were enrolled in Berlin, Germany; Basel, Switzerland; and Cleveland, Ohio upon emergency department or hospital admission. PAXgene Blood RNA was extracted and 29 host mRNAs were quantified. IMX-BVN-3 categorized patients into very unlikely, unlikely, possible, and very likely bacterial and viral interpretation bands. IMX-BVN-3 results were compared with clinically adjudicated infection status. Results IMX-BVN-3 categorized 102 of 111 (91.9%) COVID-19 patients into very likely or possible, 7 (6.3%) into unlikely, and 2 (1.8%) into very unlikely viral bands. Approximately 94% of patients had IMX-BVN-3 unlikely or very unlikely bacterial results. Among 7 (6.3%) patients with possible (n = 4) or very likely (n = 3) bacterial results, 6 (85.7%) had clinically adjudicated bacterial coinfection or superinfection. Overall, 19 of 111 subjects for whom adjudication was performed had a bacterial infection; 7 of these showed a very likely or likely bacterial result in IMX-BVN-3. Conclusions IMX-BVN-3 identified COVID-19 patients as virally infected and identified bacterial coinfections and superinfections. Future studies will determine whether a point-of-care version of the classifier may improve the management of COVID-19 patients, including appropriate antibiotic use

    Electrolyte design for suspended particulates in electrolyte jet processing

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    The addition of particles (<1 μm) to electrolyte feedstocks results in marked changes to the morphology of deposits when electrolyte jet processing (EJP) compared to electrolyte only feedstocks. Through the use of a ‘carrier’ electrolyte in additive mode these particulates may become embedded within a deposited matrix. These also serve as nucleation points for crystallisation. This allows opportunities for creating complex surface coatings and incorporating materials independent of crystallisation phenomena. Control of the microscale morphology of these is demonstrated here through the addition of the brightening agent – thiourea and the buffer – sodium sulfate. Here acidity and hence electric surface potential are modified and the response upon deposition evaluated

    EFAS upgrade for the extended model domain

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    This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a policy position of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication.JRC.E.1-Disaster Risk Managemen
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