Interaction between a dark spot and a two-dimensional nonlinear photonic lattice with fully incoherent white light

We study experimentally the interaction of a dark spot with a nonlinear photonic lattice with fully incoherent white light emitted from an incandescent bulb in the self-defocussing photovoltaic media when the dark spot is aimed at different positions of lattices with different lattice spacing. In this case a host of novel phenomena is demonstrated, including dark spot induced lattice dislocation-deformation, the annihilation of the dark spot and so on. Results demonstrate that the interaction between incoherent dark spot and photonic lattice is always attraction and the large-spacing photonic lattice is analogous to the continuous medium.     

A transmission line model for subwavelength metallic grating with single cut

A transmission line model for subwavelength metallic grating with single cut is presented. The model is based on analogy between the subwavelength metallic structure and the microwave transmission line theory. The analytical expression for the transmission is derived by the transfer matrix method. To confirm our model, the finite-difference time-domain (FDTD) method simulations are carried out. The influences of the position of the cuts on the higher modes of slit are presented. It is found that the transmission line model gives analytical prediction about the evolution of the transmission spectra.     

Synthesis and physical properties of antiperovskite-type compound In0.95CNi3

The compound In_0.95CNi₃ has been synthesized and the basic properties have been investigated. It has the typical antiperovskite structure (space group Pm3m, lattice parameter 3.7836 Å). The electronic specific coefficient γ and Debye temperature Θ_D are found to be 14.1 mJ/mol K² and 372 K, respectively. It behaves as a ferromagnetic metal below the Curie temperature (577 K). The emergence of ferromagnetism is suggested to originate from the deviation of the Ni/In atomic ratio from the ideal stoichiometry. The possible mechanisms have been discussed in detail in terms of this deviation.     

Influence of atomic densities on propagation property for ultrashort pulses in a two-level medium

The influence of atomic densities on the propagation property for ultrashort pulses in a two-level atom (TLA) medium is investigated. With higher atomic densities, the self-induced transparency (SIT) cannot be recovered even for 2π ultrashort pulses. New features such as pulse splitting, red-shift and blue-shift of the corresponding spectra arise, and the component of central frequency gradually disappears.     

The pure-shear mode solidly mounted resonator based on c-axis oriented ZnO film

In this paper, we fabricate a pure-shear mode film bulk acoustic resonator based on c-axis oriented ZnO film. The resonator is consisted of an in-plane electrode, a highly c-axis oriented ZnO film and a SiO₂/W Bragg reflector. The shear mode wave is excited by the lateral electric field. The resonator works in a pure-shear mode with the resonance frequency near 1.5 GHz and the Q-factor of 479 in air. There is no obvious longitudinal mode resonance in the frequency response, which can be explained that the electric field component normal to the surface is very weak and the Bragg reflector has the effective frequency selectivity for the shear mode. Importantly for sensors, the immersion into de-ionized water and glycerol liquid still allows for a Q-factor up to 335 and 220, respectively. This resonator shows the potential as mass loading sensors for biochemical application.     

A thioester substrate binds to the enzyme Arthrobacter thioesterase in two ionization states: evidence from Raman difference spectroscopy

4‐Hydroxybenzoyl‐CoA (4‐HB‐CoA) thioesterase from Arthrobacter is the final enzyme catalyzing the hydrolysis of 4‐HB‐CoA to produce coenzyme A and 4‐hydroxybenzoic acid in the bacterial 4‐chlorobenzoate dehalogenation pathway. Using a mutation E73A that blocks catalysis, stable complexes of the enzyme and its substrate can be analyzed by Raman difference spectroscopy. Here we have used Raman difference spectroscopy, in the non‐resonance regime, to characterize 4‐HB‐CoA bound in the active site of the E73A thioesterase. In addition, we have characterized complexes of the wild‐type enzyme complexed with the unreactive substrate analog 4‐hydroxyphenacyl‐CoA (4‐HP‐CoA). Both sets of complexes show evidence for two forms of the ligand in the active site: one population has the 4‐hydroxy group protonated, 4‐OH; while the second has the group as the hydroxide, 4‐O⁻. For bound 4‐HP‐CoA, X‐ray data show that glutamate 78 is close to the 4‐OH in the complex and it is likely that this is the proton acceptor for the 4‐OH proton. Although the pK_a of the 4‐OH group on the free substrate in aqueous solution is 8.6, the relative populations of ionized and neutral 4‐HB‐CoA bound to E73A remain invariant between pH 7.3 and 9.8. The invariance with pH suggests that the 4‐OH and the ‐COO⁻ of E78 constitute a tightly coupled pair where their separate pK_a ‘s lose their individual qualities. Narrow band profiles are seen in the CO double bond and C‐S regions, suggesting that the hydrolyzable thioester group is rigidly bound in the active site in a syn gauche conformation. Copyright © 2011 John Wiley & Sons, Ltd.     

Bounds for the blowup time of the solutions to quasi-linear parabolic problems

In this paper, we obtain the lower and the upper bounds of the blowup time of the solutions to quasi-linear parabolic problems subject to Dirichlet(or Neumann) boundary condition. Our results are suitable for the problems with any smooth bounded domain ${\Omega \subset \mathbb{R}^n}$ and ${n \geq 3}$ . In some special cases, we can even get the exact values of blowup time.     

Hydrothermal preparation and photoluminescence of bundle-like structure of ZnWO4 nanorods

ZnWO₄ nanorods with a bundle-like structure were synthesized at 180°C for 12 h by a hydrothermal technology from Na₂WO₄⋅2H₂O and ZnSO₄⋅7H₂O in the presence of sodium dodecyl sulfate (SDS). The as-synthesized bundle-like structure of ZnWO₄ nanorods was characterized by various techniques: TEM, XRD and EDS. The luminescence properties of the bundle-like structure of the ZnWO₄ nanorods were investigated by photoluminescence (PL) spectroscopy.     

Enhanced dielectric properties of lead barium zirconate thin films by manganese doping

(Pb_0.5Ba_0.5)ZrO₃ (PBZ) and 1 mol% Mn-doped (Pb_0.5Ba_0.5)ZrO₃ (Mn-PBZ) sol were successfully fabricated, and corresponding thin films were deposited on Pt(1 1 1)/TiO₂/SiO₂/Si(1 0 0) substrates by spin-coating method. Effects of Mn doping on the microstructure and electrical properties of PBZ thin films were investigated systemically. X-ray diffraction patterns showed that both films had a polycrystalline perovskite structure, and that the degree of (1 1 1) orientation were increased by Mn doping. Dielectric measurements illustrated that Mn-doped PBZ thin films not only had a larger dielectric constant, but also possessed a smaller dielectric loss. Accordingly, the tunability and the figure of merit of PBZ films were improved by Mn doping.