Search results for "Metals"
showing 10 items of 2013 documents
Evaluation of thin film adhesion to a compliant substrate by the analysis of progressive buckling in the fragmentation test
2009
The interface toughness of a thin coating/compliant substrate system is estimated based on the evolution of coating buckle patterns in the fragmentation test. The linear density of coating buckles as a function of applied strain is determined experimentally for a SiOx coating deposited on a polyethylene terephthalate film. A three-dimensional non-linear finite element model is developed to simulate the process of buckle formation in a single narrow coating strip. The elastic energy released during buckling-driven delamination is obtained from the energy balance in the system before and after the buckling event. Both the interface adhesion and the total energy release rate, which includes th…
Evaluation of the toxicity of mussels from 2 sites of the Moroccan Atlantic Coast (Jorf Lasfar and Oualidia) used as bioindicators of contamination :…
2012
Toxic substances generated by various human activities are spilled on different area of the Moroccan coast. Shellfishes can concentrate pollutants and have some adverse effects on human health through the food chain. Despite the strengthening of food safety rules, the involvement of chemical pollution of food on metabolic disorders is not known. To predict the impact of pollutants on the aquatic ecosystem and human health, the development of appropriate biomonitoring tools is required.We quantified heavy metals (Cd, Cr and Pb) in mussels (Mytilus galloprovincialis) from two sites of Moroccan Atlantic coast (industrial site Jorf Lasfar (JL) and touristic site Oualidia (OL)) due to the proxim…
Characterization of small HSPs from Anemonia viridis reveals insights into molecular evolution of alpha crystallin genes among cnidarians.
2014
Gene family encoding small Heat-Shock Proteins (sHSPs containing α-crystallin domain) are found both in prokaryotic and eukaryotic organisms; however, there is limited knowledge of their evolution. In this study, two small HSP genes termed AvHSP28.6 and AvHSP27, both organized in one intron and two exons, were characterised in the Mediterranean snakelocks anemone Anemonia viridis. The release of the genome sequence of Hydra magnipapillata and Nematostella vectensis enabled a comprehensive study of the molecular evolution of α-crystallin gene family among cnidarians. Most of the H. magnipapillata sHSP genes share the same gene organization described for AvHSP28.6 and AvHSP27, differing from …
Particle transport in recirculated liquid metal flows
2008
PurposeAims to present recent activities in numerical modeling of turbulent transport processes in induction crucible furnace.Design/methodology/approach3D large eddy simulation (LES) method was applied for fluid flow modeling in a cylindrical container and transport of 30,000 particles was investigated with Lagrangian approach.FindingsParticle accumulation near the side crucible boundary is determined mainly by the ρp/ρ ratio and according to the presented results. Particle settling velocity is of the same order as characteristic melt flow velocity. Particle concentration homogenization time depends on the internal flow regime. Separate particle tracks introduce very intensive mass exchang…
Permanent magnet centrifugal pump for liquid aluminium stirring
2016
In liquid aluminium processing, it is important to ensure continuous mixing of the molten metal to ensure temperature and composition homogeneity, and to improve degassing of the metal. Aluminium and its alloys are often processed in special degassing chambers after preparation in order to avoid segregation and to improve material structure, and to avoid gas pores. This extra step increases material costs and may cause material contamination. In this article, we present the idea to use centrifugal permanent magnet stirrer to induce liquid aluminium motion through thick furnace wall by creating high-speed local liquid metal jet. Analytical estimation, numerical modelling and experimental tes…
Numerical and experimental study of liquid metal stirring by rotating permanent magnets
2018
In this work, we study liquid gallium stirring by rotating permanent magnets. We demonstrate possibility of easily creating different flow patterns by rotating permanent magnets, which can be industrially important for controlling heat and mass transfer processes in the system. Unlike the typical approach of simulating magnet rotation as a transient problem and time-averaging the Lorentz forces, we solve the magnet rotation as a harmonic (frequency domain) problem, which leads to forces equal to time-averaged ones and decreases the simulation time considerably. Numerical results are validated using qualitative flow structure results from the neutron radiography visualization of tracer parti…
Simultaneous detection of copper and mercury in water samples using in-situ pH control with electrochemical stripping techniques
2023
The performance of electrochemical sensors using an in situ pH control technique for detection of mercury and copper in neutral solutions is described herein. Sensors are comprised of two distinct parallel gold interdigitated microband electrodes each of which may be polarised separately. Biasing one interdigitated “protonator” electrode sufficiently positive to begin water electrolysis, resulted in the production of H+ ions, which, consequently droped the interfacial pH at the other second interdigitated “sensing” electrode. This decrease in pH permitted the electrodeposition (and consequent stripping) of metals at a sensing electrode without the need to acidify the whole test solution. In…
Lumbriculus variegatus (Annelida) biological responses and sediment sequential extractions indicate ecotoxicity of lake sediments contaminated by bio…
2018
Abstract We assessed potential ecotoxicity of lake sediments affected by biomining effluents in northeastern Finland. Growth, reproduction and behavior of the sediment-dwelling oligochaete Lumbriculus variegatus (Muller 1774) were used as ecotoxicity endpoints. Standardized chronic bioassays were used for growth and reproduction, and acute and chronic tests with Multispecies Freshwater Biomonitor (MFB) for behavior assessments. Sequential extractions were used to characterize metal bioavailability and exposure conditions in the sediments, which indicated mining-induced contamination gradients of S, Cu, Ni and U and also bioavailability gradients of S and Ni. Among the ecotoxicity endpoints,…
Toxicity of Mining-Contaminated Lake Sediments to Lumbriculus variegatus
2021
AbstractBoreal lakes with soft water and low buffering capacity are susceptible to excess ion loading resulting from metal mining. The impact of two Finish mining sites in downstream lakes was assessed with a chronic sediment toxicity test using a laboratory-reared freshwater Lumbriculus variegatus (Oligochaeta). The test organisms were exposed to mining-contaminated natural lake sediments and hypolimnion water (HLW) or artificial freshwater (AFW) as overlying water in two independent experimental setups. In both test setups, growth and reproduction of L. variegatus were lower in sediments from the lakes receiving high amount of mining effluents from the mines nearby. In the biomining site,…
Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex
2019
Abstract Photoactive metal complexes employing Earth‐abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non‐innocence to tune the luminescence and photochemistry of the excited state of the [CrN6] chromophore [Cr(tpe)2]3+ with close to octahedral symmetry (tpe=1,1,1‐tris(pyrid‐2‐yl)ethane). [Cr(tpe)2]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2]3+ are redox non‐innocent, …