11,791 research outputs found

    Tungsten fibre reinforced Zr-based bulk metallic glass composites

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    A Zr-based bulk metallic glass (BMG) alloy with the composition (Zr55Al10Ni5Cu30)98.5Si1.5 was used as the base material to form BMG composites. Tungsten fiber reinforced BMG composites were successfully fabricated by pressure metal infiltration technique, with the volume fraction of the tungsten fiber ranging from 10% to 70%. Microstructure and mechanical properties of the BMG composites were investigated. Tungsten reinforcement significantly increased the material’s ductility by changing the compressive failure mode from single shear band propagation to multiple shear bands propagation, and transferring stress from matrix to tungsten fibers

    Powder to become crystal clear

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    Microwave method for high-frequency properties of graphene

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    Graphene is a remarkable material, which is yet to make the transition from unique laboratory phenomenon to useful industrial material. One missing element in the development process is a quick method of quality control of the electrical properties of graphene which may be applied in, or close to, the graphene growth process on an industrial scale. In this study, the authors describe a non-contact method using microwave resonance which potentially solves this problem. They describe the technique, consider its limitations and accuracy and suggest how the method may have future take up.UK NMS Programme, the EU EMRP project ‘GraphOhm’ and ‘MetNEMS’. The EMRP (European Metrology Research Programme

    Exotic mesons from quantum chromodynamics with improved gluon and quark actions on the anisotropic lattice

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    Hybrid (exotic) mesons, which are important predictions of quantum chromodynamics (QCD), are states of quarks and anti-quarks bound by excited gluons. First principle lattice study of such states would help us understand the role of ``dynamical'' color in low energy QCD and provide valuable information for experimental search for these new particles. In this paper, we apply both improved gluon and quark actions to the hybrid mesons, which might be much more efficient than the previous works in reducing lattice spacing error and finite volume effect. Quenched simulations were done at β=2.6\beta=2.6 and on a ξ=3\xi=3 anisotropic 123×3612^3\times36 lattice using our PC cluster. We obtain 2013±26±712013 \pm 26 \pm 71 MeV for the mass of the 1−+1^{-+} hybrid meson qˉqg{\bar q}qg in the light quark sector, and 4369±37±994369 \pm 37 \pm 99Mev in the charm quark sector; the mass splitting between the 1−+1^{-+} hybrid meson cˉcg{\bar c}c g in the charm quark sector and the spin averaged S-wave charmonium mass is estimated to be 1302±37±991302 \pm 37 \pm 99 MeV. As a byproduct, we obtain 1438±32±571438 \pm 32 \pm 57 MeV for the mass of a P-wave 1++1^{++} uˉu{\bar u}u or dˉd{\bar d}d meson and 1499±28±651499 \pm 28 \pm 65 MeV for the mass of a P-wave 1++1^{++} sˉs{\bar s}s meson, which are comparable to their experimental value 1426 MeV for the f1(1420)f_1(1420) meson. The first error is statistical, and the second one is systematical. The mixing of the hybrid meson with a four quark state is also discussed.Comment: 12 pages, 3 figures. Published versio

    What factors impact on primary students' online engagement for learning and entertainment at home

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    Informed by the difference of children’s Internet use in formal and informal contexts, this study aims to move away from studying children’s more predictable Internet use in school settings to learning how children use the Internet at home, and what factors impact their online behavior in such contexts. Students from grade 3 to 6 from a school in a medium sized city in China participated in the study. The data reveals that children use the Internet for both entertainment and learning purposes and these two factors are correlated. However, factors influencing Internet use for the two purposes are to some extent different. The study suggests that there is a need to zoom in and analyze children’s Internet use in informal contexts, rather than assume that learning at home is just an extension of learning at school. Policy makers and educators may use information about how children use the internet at home to improve pedagogy to bridge the gap between school and home.postprin

    Structural Basis for Human PECAM-1-Mediated Trans-homophilic Cell Adhesion

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