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Wong G.,CAS Institute of Microbiology | Wong G.,Chinese Academy of SciencesBeijing | Liu W.,CAS Institute of Microbiology | Liu W.,Chinese Academy of SciencesBeijing | And 9 more authors.
Cell Host and Microbe | Year: 2015

Super-spreading occurs when a single patient infects a disproportionate number of contacts. The 2015 MERS-CoV, 2003 SARS-CoV, and to a lesser extent 2014-15 Ebola virus outbreaks were driven by super-spreaders. We summarize documented super-spreading in these outbreaks, explore contributing factors, and suggest studies to better understand super-spreading. © 2015 Elsevier Inc.

Ding R.,Peking University | Li T.,CAS Institute of Theoretical Physics | Li T.,University of Electronic Science and Technology of China | Staub F.,CERN | And 3 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We propose the supersymmetric Standard Models (SSMs) with a pseudo-Dirac gluino from hybrid F- and D-term supersymmetry (SUSY) breaking. Similar to the SSMs before the LHC, all the supersymmetric particles in the minimal SSM obtain the SUSY breaking soft terms from the traditional gravity mediation and have masses within about 1 TeV except gluino. To evade the LHC SUSY search constraints, the gluino also has a heavy Dirac mass above 3 TeV from D-term SUSY breaking. Interestingly, such a heavy Dirac gluino mass will not induce the electroweak fine-tuning problem. We realize such SUSY breaking via an anomalous U(1)X gauge symmetry inspired from string models. To maintain the gauge coupling unification and increase the Higgs boson mass, we introduce extra vectorlike particles. We study the viable parameter space which satisfies all the current experimental constraints and present a concrete benchmark point. This kind of model not only preserves the merits of pre-LHC SSMs such as naturalness, dark matter, etc., but also solves the possible problems in the SSMs with Dirac gauginos due to the F-term gravity mediation. © 2015 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "http://creativecommons.org/licenses/by/3.0/" Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Chen W.,National University of Singapore | Wang Y.,Chinese Academy of SciencesBeijing | Ji W.,National University of Singapore
Journal of Physical Chemistry C | Year: 2015

We report our observation of two-photon absorption (2PA) in graphene enhanced by the excitonic Fano resonance at the saddle point with femtosecond laser pulses in the spectral range from 1.8 to 2.9 eV (or, from 435 to 700 nm). On the basis of the second-order, time-dependent perturbation theory on interband transitions among three states near the saddle point of two-dimensional systems (used in the Bassani-Hassan theoretical model), we develop a semiempirical model to take excitons in graphene into consideration. We find that the model is in agreement with the photon-energy dependence of the observed 2PA spectrum with a scaling factor of B = (1-5) × 102 cm/MW/eV5. © 2015 American Chemical Society.

Wang J.,CAS Institute of Process Engineering | Zhao B.,Chinese Academy of SciencesBeijing | Li J.,CAS Institute of Process Engineering
AIChE Journal | Year: 2016

Mesoscience has recently been proposed as a possible general concept for describing complex systems far from equilibrium, however, concrete formulations are needed, and particularly, a statistical mechanics foundation of mesoscience remains to be explored. To this end, the mathematical theory of stochastic geometry is combined with the energy minimization multi-scale (EMMS) principle under the concept of mesoscience to propose a statistical mechanics framework. An EMMS-based particle velocity distribution function is then derived as an example to show how the proposed framework works, and more importantly, as a first key step toward a generalized kinetic theory for heterogeneous gas-solid flow. It was shown that the resultant EMMS-based distribution is bimodal, instead of the widely-used Maxwellian distribution, but it reduces to the Maxwellian distribution when the gas-solid system is homogeneous. The EMMS-based distribution is finally validated by comparing its prediction of the variance of solid concentration fluctuation and granular temperature with experimental data available in literature. © 2016 American Institute of Chemical Engineers.

Jiang F.,CAS Shanghai Institute of Applied Physics | Jiang F.,University of Chinese Academy of Sciences | Li C.,CAS Shanghai Institute of Applied Physics | Fu H.,CAS Shanghai Institute of Applied Physics | And 5 more authors.
Journal of Physical Chemistry C | Year: 2015

A temperature-dependent X-ray absorption fine structure (XAFS) study was performed to investigate structural changes in the 1-hexyl-3-methylimidazolium bromine (C6mimBr) ionic liquid (IL) confined within the channels of multiwalled carbon nanotubes (MWCNTs). The XAFS spectra at room temperature confirmed the charge transfer from the bromine anion of the encapsulated IL to the MWCNTs. R-space analysis at ambient temperature revealed the reduced distance between the anions and cations in the confined IL compared with that in the bulk state. Interfacial-induced solidification and nanoconfinement in MWCNTs induced the self-assembly of ions in the confined IL to form a layered arrangement near the inner surface of MWCNTs. In situ XAFS analysis revealed that with increasing temperature charge transferred from MWCNTs to Br anions because of the damage from the conjugative effect between Br and MWCNTs and the relatively strong electronegativity of Br atoms. R-space analysis also showed gradual reduction in distance between cations and anions with increasing temperature. This finding indicated that the anion moved toward the ring planar, and ions rearranged from the layered to the near-planar structure. Raman and XRD experiments confirmed the structural transformation of the confined IL at increased temperature. © 2015 American Chemical Society.

Liu X.,Chinese Academy of SciencesBeijing | Wang L.,CAS Institute of Process Engineering | Ge W.,CAS Institute of Process Engineering
AIChE Journal | Year: 2016

Statistical properties of particles in heterogeneous gas-solid flow were numerically investigated based on the results of a three-dimensional large-scale direct numerical simulation (DNS). Strong scale-dependence and local non-equilibrium of these properties, especially the particle fluctuating velocity (PFV) or granular temperature, were observed to be related to the effect of meso-scale structures formed by the compromise in competition between fluid and particle dominated mechanisms. To quantify such effects, the heterogeneous structures were partitioned into a gas-rich dilute phase and a solid-rich dense phase according to the particle-scale voidage defined through the Voronoi tessellation. Non-equilibrium features, such as the deviation of PFV from Gaussian distribution and anisotropy, were found even in phase-specific properties. A new distribution function for the PFV well characterizing these features was obtained by fitting the DNS results, which takes a typical bi-disperse mode, with phase-specific granular temperatures. The implications of these findings to the kinetic theory of granular flow and traditional continuum models of gas-solid flow were also discussed. © 2016 American Institute of Chemical Engineers AIChE J, 2016 © 2016 American Institute of Chemical Engineers.

Zhang W.,Beijing National Laboratory for Molecular SciencesInstitute of Chemistry | Yu G.,Chinese Academy of SciencesBeijing
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2016

Constructing planar, rigid, and high electronically delocalized π-conjugated molecular system is the most basic requirements of obtaining high-performance polymeric semiconductors for organic field-effect transistors (OFETs). In this regard, diarylethylene (DAE)-based polymers show great potential because many substantive progresses related to polymer field-effect transistors had been achieved from the kind of polymer materials in recent years. In the brief review, series of DAE-based polymer are highlighted, based on which several design strategies have been summarized by the way of comparative research method. These strategies have important guiding significance not only for further developing new DAE-based and other polymeric semiconductors for OFETs but also for developing specific polymeric semiconductors for other organic electronics, such as organic photovoltaics and organic light-emitting diodes. © 2016 Wiley Periodicals, Inc.

Fan J.,Chinese Academy of SciencesBeijing | Cao Y.,Yancheng Institute of Technology | Yuan F.,Chinese Academy of SciencesBeijing
Journal of Magnetism and Magnetic Materials | Year: 2015

Abstract In the present work, iron nanocubes, nanorods and nanowires are successfully synthesized by one-step reduction approach in a solvothermal environment. It is analyzed that the iron nanocubes, nanorods and nanowires belong to the pure body-centered cubic structure of α-Fe. Effects of additive sort and the amount of Anionic Gemini surfactant 12-4-12 on the morphology evolution of Fe are discussed based on SEM and TEM images. The possible formation mechanisms of iron nanocubes, nanorods and nanowires are proposed. The Anionic Gemini surfactant 12-4-12 regarded as template plays an important role in the formation of iron nanocrystals. The microwave electromagnetic (EM) (80 wt% Fe) and calculated microwave-absorbing (0.5 mm thickness) properties in 2-18 GHz of the iron nanocubes, nanorods and nanowires are studied systematically. Results show that iron nanowires are superior to nanorods and nanocubes, which indicates the potential to be a super-thin microwave absorber. © 2015 Elsevier B.V.

Gu Y.,U.S. Geological Survey | Wylie B.K.,U.S. Geological Survey | Zhang L.,Chinese Academy of SciencesBeijing | Gilmanov T.G.,South Dakota State University
Biomass and Bioenergy | Year: 2012

This study evaluates the carbon fluxes and trends and examines the environmental sustainability (e.g., carbon budget, source or sink) of the potential biofuel feedstock sites identified in the Greater Platte River Basin (GPRB). A 9-year (2000-2008) time series of net ecosystem production (NEP), a measure of net carbon absorption or emission by ecosystems, was used to assess the historical trends and budgets of carbon flux for grasslands in the GPRB. The spatially averaged annual NEP (ANEP) for grassland areas that are possibly suitable for biofuel expansion (productive grasslands) was 71-169 g C m-2 year-1 during 2000-2008, indicating a carbon sink (more carbon is absorbed than released) in these areas. The spatially averaged ANEP for areas not suitable for biofuel feedstock development (less productive or degraded grasslands) was -47 to 69 g C m-2 year-1 during 2000-2008, showing a weak carbon source or a weak carbon sink (carbon emitted is nearly equal to carbon absorbed). The 9-year pre-harvest cumulative ANEP was 1166 g C m-2 for the suitable areas (a strong carbon sink) and 200 g C m-2 for the non-suitable areas (a weak carbon sink). Results demonstrate and confirm that our method of dynamic modeling of ecosystem performance can successfully identify areas desirable and sustainable for future biofuel feedstock development. This study provides useful information for land managers and decision makers to make optimal land use decisions regarding biofuel feedstock development and sustainability. © 2012 Elsevier Ltd.

Wu X.,Chinese Academy of SciencesBeijing | Ma J.,Chinese Academy of SciencesBeijing | Ma Q.,Chinese Academy of SciencesBeijing | Xu S.,Chinese Academy of SciencesBeijing | And 5 more authors.
Journal of Materials Chemistry A | Year: 2015

Sodium-ion batteries have attracted extensive attention for large-scale energy storage applications for renewable energy and smart grids owing to their abundant sodium resources and potential low cost. Compared with the numerous available cathodes, very few anodes are viable for sodium-ion batteries. Here we report a highly safe and low-cost nanocomposite, disodium 2,5-dihydroxy-1,4-benzoquinone (Na2C6H2O4)/CNT, prepared by a simple spray drying method, as a high performance anode for sodium-ion batteries. The resulting nanocomposite exhibits a reversible capacity of 259 mA h g-1 with a first Coulombic efficiency of 88% and excellent rate performance. The average sodium storage voltage is 1.4 V, which prevents the formation of a solid electrolyte interphase layer and consequently ensures high safety, high first Coulombic efficiency and superior rate performance. This journal is © The Royal Society of Chemistry.

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