12,239 research outputs found

    Phase Control on Surface for the Stabilization of High Energy Cathode Materials of Lithium Ion Batteries.

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    The development of high energy electrode materials for lithium ion batteries is challenged by their inherent instabilities, which become more aggravated as the energy densities continue to climb, accordingly causing increasing concerns on battery safety and reliability. Here, taking the high voltage cathode of LiNi0.5Mn1.5O4 as an example, we demonstrate a protocol to stabilize this cathode through a systematic phase modulating on its particle surface. We are able to transfer the spinel surface into a 30 nm shell composed of two functional phases including a rock-salt one and a layered one. The former is electrochemically inert for surface stabilization while the latter is designated to provide necessary electrochemical activity. The precise synthesis control enables us to tune the ratio of these two phases, and achieve an optimized balance between improved stability against structural degradation without sacrificing its capacity. This study highlights the critical importance of well-tailored surface phase property for the cathode stabilization of high energy lithium ion batteries

    Rod-like mesoporous silica nanoparticles with rough surfaces for enhanced cellular delivery

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    Novel rod-like mesoporous silica nanoparticles with a rough surface have been prepared with 37% higher cellular uptake and drug delivery efficacy compared to their counterparts with a smooth surface

    New Vacuum Solar Telescope and Observations with High Resolution

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    The New Vacuum Solar Telescope (NVST) is a 1 meter vacuum solar telescope that aims to observe the fine structures on the Sun. The main tasks of NVST are high resolution imaging and spectral observations, including the measurements of solar magnetic field. NVST is the primary ground-based facility of Chinese solar community in this solar cycle. It is located by the Fuxian Lake of southwest China, where the seeing is good enough to perform high resolution observations. In this paper, we first introduce the general conditions of Fuxian Solar Observatory and the primary science cases of NVST. Then, the basic structures of this telescope and instruments are described in detail. Finally, some typical high resolution data of solar photosphere and chromosphere are also shown.Comment: 16 pages, 14 figures, accepted by RAA (Research in Astronomy and Astrophysics

    A simulation study on the measurement of D0-D0bar mixing parameter y at BES-III

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    We established a method on measuring the \dzdzb mixing parameter yy for BESIII experiment at the BEPCII e+ee^+e^- collider. In this method, the doubly tagged ψ(3770)D0D0\psi(3770) \to D^0 \overline{D^0} events, with one DD decays to CP-eigenstates and the other DD decays semileptonically, are used to reconstruct the signals. Since this analysis requires good e/πe/\pi separation, a likelihood approach, which combines the dE/dxdE/dx, time of flight and the electromagnetic shower detectors information, is used for particle identification. We estimate the sensitivity of the measurement of yy to be 0.007 based on a 20fb120fb^{-1} fully simulated MC sample.Comment: 6 pages, 7 figure

    Reconstructing the properties of dark energy from recent observations

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    We explore the properties of dark energy from recent observational data, including the Gold Sne Ia, the baryonic acoustic oscillation peak from SDSS, the CMB shift parameter from WMAP3, the X-ray gas mass fraction in cluster and the Hubble parameter versus redshift. The ΛCDM\Lambda CDM model with curvature and two parameterized dark energy models are studied. For the ΛCDM\Lambda CDM model, we find that the flat universe is consistent with observations at the 1σ1\sigma confidence level and a closed universe is slightly favored by these data. For two parameterized dark energy models, with the prior given on the present matter density, Ωm0\Omega_{m0}, with Ωm0=0.24\Omega_{m0}=0.24, Ωm0=0.28\Omega_{m0}=0.28 and Ωm0=0.32\Omega_{m0}=0.32, our result seems to suggest that the trend of Ωm0\Omega_{m0} dependence for an evolving dark energy from a combination of the observational data sets is model-dependent.Comment: 16 pages, 15 figures, To appear in JCA
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