110 research outputs found

    Long-term changes in acidification and recovery at nine calibrated catchments in Norway, Sweden and Finland

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    International agreements to reduce the emissions of acidifying pollutants have resulted in major changes in deposition of sulphur and nitrogen in southern Scandinavia over the past 25 years. Long-term monitoring of deposition and run-off chemistry over the past 12-25 years at nine small calibrated catchments in Finland, Norway and Sweden provide the basis for analysis of trends with special attention to recovery in response to decreased sulphur and nitrogen deposition in the 1980s and 1990s. During the 1980s and 1990s sulphate deposition in the region decreased by 30 to 60%, whereas inorganic nitrogen deposition showed very little change until the mid-1990s. Deposition of non-marine base cations (especially calcium) declined in the 1990s most markedly in southern Finland. Run-off response to these changes in deposition has been rapid and clear at the nine catchments. Sulphate and base cations (mostly calcium) concentrations declined and acid neutralising capacity increased. Occasional years with unusually high inputs of sea-salt confound the general trends. Trends at all the catchments show the same general picture as that from small lakes in Scandinavia and in acid-sensitive waters elsewhere in Europe.</p> <p style='line-height: 20px;'><b>Keywords: </b>acidification, recovery, Scandinavia, catchment, trend analysi

    Long-term changes in acidification and recovery at nine calibrated catchments in Norway, Sweden and Finland

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    International audienceInternational agreements to reduce the emissions of acidifying pollutants have resulted in major changes in deposition of sulphur and nitrogen in southern Scandinavia over the past 25 years. Long-term monitoring of deposition and run-off chemistry over the past 12-25 years at nine small calibrated catchments in Finland, Norway and Sweden provide the basis for analysis of trends with special attention to recovery in response to decreased sulphur and nitrogen deposition in the 1980s and 1990s. During the 1980s and 1990s sulphate deposition in the region decreased by 30 to 60%, whereas inorganic nitrogen deposition showed very little change until the mid-1990s. Deposition of non-marine base cations (especially calcium) declined in the 1990s most markedly in southern Finland. Run-off response to these changes in deposition has been rapid and clear at the nine catchments. Sulphate and base cations (mostly calcium) concentrations declined and acid neutralising capacity increased. Occasional years with unusually high inputs of sea-salt confound the general trends. Trends at all the catchments show the same general picture as that from small lakes in Scandinavia and in acid-sensitive waters elsewhere in Europe. Keywords: acidification, recovery, Scandinavia, catchment, trend analysi

    Continuous demagnetization assessment for triple redundant 9-phase fault-tolerant permanent magnet machine

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    In this study, the risk of partial irreversible demagnetisation of a triple redundant, nine-phase fault tolerant machine based on permanent-magnet-assisted synchronous reluctance machine topology has been comprehensively assessed under various faults, including the worst case scenario when the applied voltage vector is in the opposite direction of the back electromotive force due to sensing and inverter control failure, by employing a continuous demagnetisation model. The dynamic response during fault transients and the post-demagnetisation performance, such as the demagnetisation distribution, reduction in the back EMF and torque, will also be analysed and compared

    Stereospecific inhibition of monoamine uptake transporters by meta-hydroxyephedrine isomers

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    Meta-hydroxyephedrine (HED) comprises four stereoisomers consisting of two enantiomeric pairs related to ephedrine and pseudoephedrine. HED is transported into adrenergic neurons and radiolabeled HED has been employed in positron emission tomography (PET) to image adrenergic neurons in vivo. To extend structure-activity analyses of binding sites within monoamine transporters and to determine which stereoisomer displayed the best selectivity for PET imaging applications, we tested the HED compounds for their abilities to inhibit [ 3 H]neurotransmitter uptake into platelets, transfected cells, and chromaffin vesicles. We hypothesized that the HED compounds would be most potent at the norepinephrine transporter (NET) compared to the serotonin or dopamine transporters and that the 1R diastereomers would be more effective than 1S diastereomers. Supporting the hypotheses, all stereoisomers were most potent at the NET and the 1R,2S stereoisomer was the most potent inhibitor overall. However, the 1S,2R isomer may be preferred for PET applications because of better selectivity among the transporters and reduced neuronal recycling.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42456/1/702-109-10-1229_21091229.pd

    Inkjet Printed Large-Area Flexible Few-Layer Graphene Thermoelectrics

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    Graphene-based organic nanocomposites have ascended as promising candidates for thermoelectric energy conversion. In order to adopt existing scalable printing methods for developing thermostable graphene-based thermoelectric devices, optimizations of both the material ink and the thermoelectric properties of the resulting films are required. Here, inkjet printed large-area flexible graphene thin films with outstanding thermoelectric properties are reported. The thermal and electronic transport properties of the films reveal the so-called phonon-glass electron-crystal character (i.e. electrical transport behaviour akin to that of few-layer graphene flakes with quenched thermal transport arising from the disordered nanoporous structure). As a result, the all-graphene films show a room-temperature thermoelectric power factor of 18.7 µW m−1 K−2, representing over a three-fold improvement to previous solution-processed all-graphene structures. Our demonstration of inkjet printed thermoelectric devices underscores the potential for future flexible, scalable and low-cost thermoelectric applications, such as harvesting energy from body heat in wearable applications.EPSRC (EP/L016087/1) Royal Academy of Engineering (Graphlex

    Computationally efficient 3D analytical magnet loss prediction in surface mounted permanent magnet machines

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    This study proposes a computationally efficient analytical method, for accurate prediction of three-dimensional (3D) eddy current loss in the rotor magnets of surface mounted permanent magnet (SPM) machines considering slotting effect. Subdomain model incorporating stator tooth tips is employed to generate the information on radial and tangential time-derivatives of 2D magnetic field (eddy current sources) within the magnet. The distribution of the eddy current sources in 3D is established for the magnets by applying the eddy current boundary conditions and the Coulomb gauge imposed on the current vector potential. The 3D eddy current distributions in magnets are derived analytically by employing the method of variable separation and the total eddy current loss in the magnets are subsequently established. The method is validated by 3D time-stepped finite element analysis for 18-slot, 8-pole and 12-slot, 8-pole permanent magnet machines. The eddy current loss variations in the rotor magnets with axial and circumferential number of segmentations are studied. The reduction of magnet eddy current loss is investigated with respect to harmonic wavelength of the source components to suggest a suitable segmentation for the rotor magnets in SPM machines

    Microscopical methods for the localization of Na + , K + -ATPase

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    Na + , K + -ATPase plays a central role in the ionic and osmotic homeostasis of cells and in the movements of electrolytes and water across epithelial boundaries. Microscopic localization of the enzyme is, therefore, of crucial importance in establishing the subcellular routes of electrolyte flow across structurally complex and functionally polarized epithelia. Recently developed approaches to the localization of Na + , K + -ATPase are reviewed. These methods rely on different properties of the enzyme and encompass cytochemical localization of the K + -dependent nitrophenylphosphatase component of the enzyme, autoradiographic localization of tritiated ouabain binding sites, and immunocytochemical localization of the holoenzyme and of its catalytic subunit. The rationales for each of these techniques are outlined as are the critieria that have been established to validate each method. The observed localization of Na + , K + -ATPase in various tissues is discussed, particularly as it relates to putative and hypothetical mechanisms that are currently thought to mediate reabsorptive and secretory electrolyte transport.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42850/1/10735_2005_Article_BF01005056.pd
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