1,747 research outputs found

    Band Structure and Quantum Conductance of Nanostructures from Maximally-Localized Wannier Functions: The Case of Functionalized Carbon Nanotubes

    Full text link
    We have combined large-scale, Γ\Gamma-point electronic-structure calculations with the maximally-localized Wannier functions approach to calculate efficiently the band structure and the quantum conductance of complex systems containing thousands of atoms while maintaining full first-principles accuracy. We have applied this approach to study covalent functionalizations in metallic single-walled carbon nanotubes. We find that the band structure around the Fermi energy is much less dependent on the chemical nature of the ligands than on the sp3sp^3 functionalization pattern disrupting the conjugation network. Common aryl functionalizations are more stable when paired with saturating hydrogens; even when paired, they still act as strong scattering centers that degrade the ballistic conductance of the nanotubes already at low degrees of coverage.Comment: To be published in Phys. Rev. Let

    Bergman kernel and complex singularity exponent

    Full text link
    We give a precise estimate of the Bergman kernel for the model domain defined by ΩF={(z,w)∈Cn+1:Imw−∣F(z)∣2>0},\Omega_F=\{(z,w)\in \mathbb{C}^{n+1}:{\rm Im}w-|F(z)|^2>0\}, where F=(f1,...,fm)F=(f_1,...,f_m) is a holomorphic map from Cn\mathbb{C}^n to Cm\mathbb{C}^m, in terms of the complex singularity exponent of FF.Comment: to appear in Science in China, a special issue dedicated to Professor Zhong Tongde's 80th birthda

    Fellhanera gyrophorica, a new European species with conspicuous pycnidia

    Get PDF
    Fellhanera gyrophorica SĂ©rus., Coppins, Diederich & Scheidegger is described as new from Europe Austria, Lithuania, Luxembourg, Poland, Switzerland and Ukraine. It is a sterile corticolous species with conspicuous and sometimes shortly stalked pycnidia whose outer walls produce gyrophoric acid. Its position in the genus Fellhanera (Pilocarpaceae) is tentative and further studies may necessitate its transfer to another genu

    Subsidizing Unit Donations: Matches, Rebates, and Discounts Compared

    Get PDF
    An influential result in the literature on charitable giving is that matching subsidies dominate rebate subsidies in raising funds. We investigate whether this result extends to ‘unit donation’ schemes, a popular alternative form of soliciting donations. There, the donors’ choices are about the number of units of a charitable good to fund at a given unit price, rather than the amount of money to give. Comparing matches and rebates as well as simple discounts on the unit price, we find no evidence of dominance in our online experiment: The three subsidy types are equally effective overall. At a more disaggregate level, rebates lead to a higher likelihood of giving while matching and discount subsidies lead to larger donations by donors. This suggests that charities using a unit donation scheme enjoy additional degrees of freedom in choosing a subsidy type. Rebates merit additional consideration if the primary goal is to attract donors

    Resonant tunneling through a C60 molecular junction in liquid environment

    Full text link
    We present electronic transport measurements through thiolated C60_{60} molecules in liquid environment. The molecules were placed within a mechanically controllable break junction using a single anchoring group per molecule. When varying the electrode separation of the C60_{60}-modified junctions, we observed a peak in the conductance traces. The shape of the curves is strongly influenced by the environment of the junction as shown by measurements in two distinct solvents. In the framework of a simple resonant tunneling model, we can extract the electronic tunneling rates governing the transport properties of the junctions.Comment: 13 pages, 4 figures. To appear in Nanotechnolog

    Novel inhibitors of human histone deacetylases: Design, synthesis and bioactivity of 3-alkenoylcoumarines

    Get PDF
    International audienceHistone deacetylases (HDACs) are well-established, promising targets for anticancer therapy due to their critical role in cancer development. Accordingly, an increasing number of HDAC inhibitors displaying cytotoxic effects against cancer cells have been reported. Among them, a large panel of chemical structures was described including coumarin-containing molecules. In this study, we described synthesis and biological activity of new coumarin-based derivatives as HDAC inhibitors. Among eight derivatives, three compounds showed HDAC inhibitory activities and antitumor activities against leukemia cell lines without affecting the viability of peripheral blood mononuclear cells from healthy donors

    A spherical source model for the thermal pulse decay method of measuring blood perfusion: a sensitivity analysis

    Get PDF
    The thermal pulse-decay method, as developed and analyzed b
    • 

    corecore