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Beijing, China

Hu J.,CAS Institute of Physics | Hu J.,Purdue University
Physical Review X | Year: 2014

Parity is a fundamental quantum number used to classify a state of matter. Materials rarely possess ground states with odd parity. We show that the superconducting state in iron-based superconductors is classified as an odd-parity s-wave spin-singlet pairing state in a single trilayer FeAs/Se, the building block of the materials. In a low-energy effective model constructed on the Fe square bipartite lattice, the superconducting order parameter in this state is a combination of an s-wave normal pairing between two sublattices and an s-wave η pairing within the sublattices. The state has a fingerprint with a real-space sign inversion between the top and bottom As/Se layers. The results suggest that iron-based superconductors are a new quantum state of matter, and the measurement of the odd parity can help to establish high-temperature superconducting mechanisms.

Li Z.-Y.,CAS Institute of Physics
Frontiers of Physics | Year: 2012

The major purpose of this paper is to present a brief overview of the history and the current status of nanophotonics research in China, and to highlight some research results in the past years made by the Chinese nanophotonics communities. I will first briefly introduce the principles of nanophotonics and several of its major disciplines including photonic crystals, plasmonics and metamaterials, and related artificial acoustic structures. Then I will highlight some major progresses made by Chinese research groups in these areas with the selection made merely based on my personal taste. The aim is to let these results better known and appreciated by researchers in the Chinese communities of nanophotonics and related areas, and provide better opportunities of researchers in different areas to have more communications. I also hope that this brief introduction will help to make a better bridge to connect Chinese nanophotonics communities with the broader communities in the world. © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.

Using dark-field scattering spectroscopy, we study the multipolar plasmon resonances in single crystallized silver nanorods. The lineshapes and homogenous linewidths of the surface plasmon resonances (SPRs) of different orders are analyzed and compared. The high-order resonances are found to sustain asymmetric Fano lineshapes and their linewidths are narrower than the dipolar resonance. A quantitative comparison using the finite element method reveals more than a three times reduction in the linewidth for the third order resonance, as compared with the dipolar one. These narrow linewidths result from the smaller radiative damping of the multipolar SPRs. Benefiting from the reduced damping, multipolar SPRs in nanorods are better candidates for many plasmonic applications, including increased-sensitivity single particle SPR sensors and reduced-threshold nanolasers.

Fang X.,CAS Institute of Physics
Nanoscale | Year: 2012

Ordered mesoporous tungsten-doped MoO(2) was synthesized by a nanocasting method. The Li storage performance of mesoporous MoO(2) is significantly improved by tungsten doping, which exhibits a reversible capacity of 700 mA h g(-1), better cycling and rate performance. This material combines the advantages of the high theoretical capacity of MoO(2) and the better electroactivity of WO(2).

Xie P.,CAS Institute of Physics
European Biophysics Journal | Year: 2013

A ribosome is an enzyme that catalyzes translation of the genetic information encoded in messenger RNA (mRNA) into proteins. Besides translation through the single-stranded mRNA, the ribosome is also able to translate through the duplex region of mRNA via unwinding the duplex. Here, based on our proposed ribosome translation model, we study analytically the dynamics of Escherichia coli ribosome translation through the duplex region of mRNA, and compare with the available single molecule experimental data. It is shown that the ribosome uses only one active mechanism (mechanical unwinding), rather than two active mechanisms (open-state stabilization and mechanical unwinding), as proposed before, to unwind the duplex. The reduced rate of translation through the duplex region is due to the occurrence of futile transitions, which are induced by the energy barrier from the duplex unwinding to the forward translocation along the single-stranded mRNA. Moreover, we also present predicted results of the average translation rate versus the external force acting on the ribosome translating through the duplex region and through the single-stranded region of mRNA, which can be easily tested by future experiments. © 2012 European Biophysical Societies' Association.

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