Plasmon hybridization in real metals

By treating free electrons in metallic nanostructures as incompressible and irrotational fluid, Plasmon hybridization (PH) method can be used as a very useful tool in interpolating the electric magnetic behaviors of complex metallic nanostructures. Using PH theory and Finite Element Method (FENI), we theoretically investigated the optical properties of some complex nanostructrus including coupled nanoparticle aggregates and nanowires. We investigated the plasmonic properties of a symmetric silver sphere heptamer and showed that the extinction spectrum exhibited a narrow Fano resonance. Using the plasmon hybridization approach and group theory we showed that this Fano resonance is caused by the interference of two bonding dipolar subradiant and superradiant plasmon modes of E1u symmetry. We investigate the effect of structural symmetry breaking and show that the energy and shape of the Fano resonance can be tuned over a broad wavelength range. We show that the wavelength of the Fano resonance depends very sensitively on the dielectric permittivity of the surrounding media. Besides heptamer, we also used plasmon hybridization method and finite element method to investigate the plasmonic properties of silver or gold nano spherical clusters. For symmetric clusters, we show how group theory can be used to identify the microscopic nature of the plasmon resonances. For larger clusters, we show that narrow Fano resonances are frequently present in their optical spectra. As an example of asymmetric clusters, we demonstrate that clusters of four identical spherical particles support strong Fano-like interference. This feature is highly sensitive to the polarization of the incident electric field due to orientation-dependent coupling between particles in the cluster. Nanowire plasmons can be launched by illumination at one terminus of the nanowire and emission can be detected at the other end of the wire. With PH theory we can predict how the polarization of the emitted light depends on the polarization of the incident light. Depending on termination shape, a nanowire can serve as either a polarization-maintaining waveguide, or as a polarization-rotating, nanoscale half-wave plate. We also investigated how the properties of a nearby substrate modify the excitation and propagation of plasmons in subwavelength silver wires

Multipartite entanglement purification with quantum nondemolition detectors

We present a scheme for multipartite entanglement purification of quantum systems in a Greenberger-Horne-Zeilinger state with quantum nondemolition detectors (QNDs). This scheme does not require the controlled-not gates which cannot be implemented perfectly with linear optical elements at present, but QNDs based on cross-Kerr nonlinearities. It works with two steps, i.e., the bit-flipping error correction and the phase-flipping error correction. These two steps can be iterated perfectly with parity checks and simple single-photon measurements. This scheme does not require the parties to possess sophisticated single photon detectors. These features maybe make this scheme more efficient and feasible than others in practical applications.Comment: 8 pages, 5 figure

Two-way Fluid-Structure Interaction Simulation of a Micro Horizontal Axis Wind Turbine

A two-way Fluid-Structure Interaction (FSI) analyses performed on a micro horizontal axis wind turbine (HAWT) which coupled the CFX solver with Structural solver in ANSYS Workbench was conducted in this paper. The partitioned approach-based non-conforming mesh methods and the k-ε turbulence model were adopted to perform the study. Both the results of one-way and two-way FSI analyses were presented and compared with each other, and discrepancy of the results, especially the mechanical properties, were analysed. Grid convergence which is crucial to the results was performed, and the relationship between the inner flow field domain (rotational domain) and the number of grids (number of cells, elements) was verified for the first time. Dynamical analyses of the wind turbine were conducted using the torque as a reference value, to verify the rationality of the model which dominates the accuracy of results. The optimal case was verified and used to conduct the study, thus, the results derived from the simulation of the FSI are accurate and credible

One-Way Fluid-Structure Interaction Simulation of an Offshore Wind Turbine

The Fluid-Structure Interaction (FSI) has gained great interest of scholars recently, meanwhile, extensive studies have been conducted by the virtue of numerical methods which have been implemented on wind turbine models. The blades of a wind turbine have been gained a deep insight into the FSI analyses, however, few studies have been conducted on the tower and nacelle, which are key components of the wind turbine, using this method. We performed the one-way FSI analysis on a 2-MW offshore wind turbine, using the Finite Volume Method (FVM) with ANSYS CFX solver and the RNG k-ε turbulence model, to achieve a comprehensive cognition of it. The grid convergence was studied and verified in this study, and the torque value is chosen to determine the optimal case. The superior case, which was chosen to conduct the FSI analysis, with a relative error is only 2.15%, thus, the accuracy of results is credible

Experimental treatment of radiation pneumonitis with human umbilical cord mesenchymal stem cells

AbstractObjectiveTo evaluate of the curative effect of human umbilical cord mesenchymal stem cells (hUC-MSCs) on rat acute radiation pneumonitis.MethodsFourty rats were randomly divided into control group, radiation group, stem cell prevention group, stem cell treatment group and prednisone treatment group. All rats except those in the control group were radiated with X ray to establish the acute radiation pneumonitis damage model. The hUC-MSCs cultured in vitro was administrated to the rats of the prevention group via tail vein (1×106 cells/kg BW) 24 h before the radiation, while the same administration was performed in the rats of the treatment group 24 h after the radiation. After 24 h post the radiation, the rats in the radiation group were given 0.4 mL physiological saline, and those in the prednisone group were given 1 mg/kg prednisone. All rats were observed and executed 72 h after the radiation to detect lung histological changes.ResultsAfter the administration of hUC-MSCs, the survival status of the rats in the prevention group and treatment group was obviously better than that in the control group. As shown by the histological staining, the morphology, proliferation activity and bronchial state of lung tissues were better in the prevention group and treatment group than in the control group.ConclusionsThe hUC-MSCs have definite therapeutic effects on acute radiation pneumonitis in rats