4,692 research outputs found

    Interfacial Properties of Bilayer and Trilayer Graphene on Metal Substrates

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    One popular approach to prepare graphene is to grow them on transition metal substrates via chemical vapor deposition. By using the density functional theory with dispersion correction, we systematically investigate for the first time the interfacial properties of bilayer (BLG) and trilayer graphene (TLG) on metal substrates. Three categories of interfacial structures are revealed. The adsorption of B(T)LG on Al, Ag, Cu, Au, and Pt substrates is a weak physisorption, but a band gap can be opened. The adsorption of B(T)LG on Ti, Ni, and Co substrates is a strong chemisorption, and a stacking-insensitive band gap is opened for the two uncontacted layers of TLG. The adsorption of B(T)LG on Pd substrate is a weaker chemisorption, with a band gap opened for the uncontacted layers. This fundamental study also helps for B(T)LG device study due to inevitable graphene/metal contact.Comment: 1 table, 8 figure

    Groundwater overexploitation in the North China Plain: A path to sustainability

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    Over-pumping of aquifers is a worldwide problem, mainly caused by agricultural water use. Among its consequences are the falling dry of streams and wetlands, soil subsidence, die-off of phreatophytic vegetation, saline water intrusion, increased pumping cost and loss of storage needed for drought relief. Stopping or reversing the trend requires management interventions. The North China Plain serves as an example. A management system is set up for a typical county. It contains three components: monitoring, decision support based on modelling, and implementation in the field. Besides all monitoring data, the decision support module contains an irrigation calculator, a box model, and a distributed groundwater model to project the outcomes of different water allocation scenarios. In view of grain security, a solution combines an adaptation of the cropping system with imports of surface water from the South. The Open Access book does not only describe the problem and the path to its solution. It also gives access to nine manuals concerning methods used. They include computer programs and the game Save the Water. The Chinese experience should be of considerable interest to other regions in the world which suffer from over-pumping of aquifers

    Loss of vesicular dopamine release precedes tauopathy in degenerative dopaminergic neurons in a Drosophila model expressing human tau.

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    While a number of genome-wide association studies have identified microtubule-associated protein tau as a strong risk factor for Parkinson's disease (PD), little is known about the mechanism through which human tau can predispose an individual to this disease. Here, we demonstrate that expression of human wild-type tau is sufficient to disrupt the survival of dopaminergic neurons in a Drosophila model. Tau triggers a synaptic pathology visualized by vesicular monoamine transporter-pHGFP that precedes both the age-dependent formation of tau-containing neurofibrillary tangle-like pathology and the progressive loss of DA neurons, thereby recapitulating the pathological hallmarks of PD. Flies overexpressing tau also exhibit progressive impairments of both motor and learning behaviors. Surprisingly, contrary to common belief that hyperphosphorylated tau could aggravate toxicity, DA neuron degeneration is alleviated by expressing the modified, hyperphosphorylated tau(E14). Together, these results show that impairment of VMAT-containing synaptic vesicle, released to synapses before overt tauopathy may be the underlying mechanism of tau-associated PD and suggest that correction or prevention of this deficit may be appropriate targets for early therapeutic intervention

    Experimental realization of optimal asymmetric cloning and telecloning via partial teleportation

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    We report an experimental realization of both optimal asymmetric cloning and telecloning of single photons by making use of partial teleportation of an unknown state. In the experiment, we demonstrate that, conditioned on the success of partial teleportation of single photons, not only the optimal asymmetric cloning can be accomplished, but also one of two outputs can be transfered to a distant location, realizing the telecloning. The experimental results represent a novel way to achieve the quantum cloning and may have potential applications in the context of quantum communication.Comment: 4 pages and 4 figure

    Groundwater overexploitation in the North China Plain: A path to sustainability

    Get PDF
    Over-pumping of aquifers is a worldwide problem, mainly caused by agricultural water use. Among its consequences are the falling dry of streams and wetlands, soil subsidence, die-off of phreatophytic vegetation, saline water intrusion, increased pumping cost and loss of storage needed for drought relief. Stopping or reversing the trend requires management interventions. The North China Plain serves as an example. A management system is set up for a typical county. It contains three components: monitoring, decision support based on modelling, and implementation in the field. Besides all monitoring data, the decision support module contains an irrigation calculator, a box model, and a distributed groundwater model to project the outcomes of different water allocation scenarios. In view of grain security, a solution combines an adaptation of the cropping system with imports of surface water from the South. The Open Access book does not only describe the problem and the path to its solution. It also gives access to nine manuals concerning methods used. They include computer programs and the game Save the Water. The Chinese experience should be of considerable interest to other regions in the world which suffer from over-pumping of aquifers
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