Two-Dimensional Self-Propelled Fish Motion in Medium： An Integrated Method for Deforming Body Dynamics and Unsteady Fluid Dynamics

We present （1） the dynamical equations of deforming body and （2） an integrated method for deforming body dynamics and unsteady fluid dynamics, to investigate a modelled freely self-propelled fish. The theoretical model and practical method is applicable for studies on the general mechanics of animal locomotion such as flying in air and swimming in water, particularly of free self-propulsion. The present results behave more credibly than the previous numerical studies and are close to the experimental results, and the aligned vortices pattern is discovered in cruising swimming.

Boundary Slip and Surface Interaction： A Lattice Boltzmann Simulation

The factors affecting slip length in Couette geometry flows are analysed by means of a two-phase mesoscopic lattice Boltzmann model including non-ideal fluid-fluid and fluid-wall interactions. The main factors influencing the boundary slip are the strength of interactions between fluid-fluid and fluid-wall particles. Other factors, such as fluid viscosity, bulk pressure may also change the slip length. We find that boundary slip only occurs under a certain density （bulk pressure）. If the density is large enough, the slip length will tend to zero. In our simulations, a low density layer near the wall does not need to be postulated a priori but emerges naturally from the underlying non-ideal mesoscopic dynamics. It is the low density layer that induces the boundary slip. The results may be helpful to understand recent experimental observations on the slippage of micro flows.

Local Homoepitaxial Growth and Optical Properties of ZnO Polar Nanoleaves

Using a mixture of ZnO and Te powders as the source material, ZnO nanoleaves with high yield and uniform morphology are fabricated by thermal evaporation. Each nanoleaf is constructed with a nanowire and a nanodisc on one side of the nanowire near the top. The polygonal nanodisc is in symmetric distribution in relation to the nanowires and has polar planes ±（0001） as surfaces. A local homoepitaxial growth mechanism of ZnO polar nanodiscs induced by Te is proposed. With thin nanodiscs, the ZnO nanoleaves could be used in nanolasers, sensors, and photoelectronic nanodevices. Room-temperature photoluminescence result implies good crystalline quality of the ZnO nanoleaves.

Strong Surface Diffusion Mediated Glancing-Angle Deposition： Growth, Recrystallization and Reorientation of Tin Nanorods

Different from usual glancing-angle deposition where low surface diffusion is necessary to form nanorods, strong surface diffusion mediated glancing-angle deposition is exemplified by growing tin nanorod films on both silicon and glass substrates simultaneously via thermal evaporation. During growth, the nanorods were simultaneously baked by the high-temperature evaporator, and therefore re-crystallized into single crystals in consequence of strong surface diffusion. The monocrystalline tin nanorods have a preferred orientation perpendicular to the substrate surface, which is quite different from the usual uniformly oblique nanorods without recrystallization.

A Theoretical and Experimental Research on Terahertz Electro-Optic Sampling at Near-Zero Optical Transmission Point

We report an improved theoretical model to characterize terahertz electro-optic （F,O） sampling detection operating at near crossed-polarizer design by considering the nonzero minimal transmission of polarizers and the polarization purity of laser beam. The proof-of-concept experiments show that the model can give quiet reasonable explanations on many experimental phenomena in THz EO detection, e.g. the modulation depth vs the different optical biases, the noise level from the balance detector vs the input probe beam power, the main origin of the background light and the incomplete cancellation of noise from the laser intensity fluctuation in balanced detection. The terahertz signals and the noises are also measured based on two different EO sampling schemes for comparison. The measured results support our model very well.

Luminescence Spectra of YGG：RE^3＋, Bi^3＋ （RE = Eu and Tb） and Energy Transfer from Bi^3＋ to RE^3＋

We investigate the luminescence properties of Bi^3＋ and RE^3＋ （RE = Tb or Eu） in a Y3Ga5O12 （YGG） host system. The additional doping of Bi^3＋ can enhance the luminescence of Th^3＋ or Eu^3＋ in this host. Energy transfer from Bi^3＋ to Tb^3＋ and Eu^3＋ is observed and the mechanism of energy transfer is investigated. Mechanism of energy transfer can be explained as electric multipole interaction since the Bi^3＋ emission band and Tb^3＋ or Eu^3＋ excitation band overlaps and the Bi^3＋ emission intensity decreases while the intensity of Tb^3＋ or Eu^3＋ increases with the increase of Tb^3＋ or Eu^3＋ concentration. Therefore, Bi^3＋ ion is a kind of efficient sensitizer to the Tb^3＋ and Eu^3＋ activators in the Y3Ga5O12 host.

Grand Canonical Ensemble Monte Carlo Simulation of Depletion Interactions in Colloidal Suspensions

Depletion interactions in colloidal suspensions confined between two parallel plates are investigated by using acceptance ratio method with grand canonical ensemble Monte Carlo simulation. The numerical results show that both the depletion potential and depletion force are affected by the confinement from the two parallel plates. Furthermore, it is found that in the grand canonical ensemble Monte Carlo simulation, the depletion interactions are strongly affected by the generalized chemical potential.

Evolution of Ge and SiGe Quantum Dots under Excimer Laser Annealing

We present different relaxation mechanisms of Ge and SiGe quantum dots under excimer laser annealing. Investigation of the coarsening and relaxation of the dots shows that the strain in Ge dots on Ge films is relaxed by dislocation since there is no interface between the Ge dots and the Ge layer, while the SiGe dots on Si0.77Ge0.23 film relax by lattice distortion to coherent dots, which results from the obvious interface between the SiGe dots and the Si0.77Ge0.23 film. The results are suggested and sustained by Vanderbilt and Wickham＇s theory, and also demonstrate that no bulk diffusion occurs during the excimer laser annealing.

Synthesis and Characterization of ZnO Nanoflowers Grown on AlN Films by Solution Deposition

ZnO nanoflowers are synthesized on AlN films by solution method. The synthesized nanoflowers are composed of nanorods, which are pyramidal and grow from a central point, thus forming structures that are flower-shaped as a whole. The nanoflowers have two typical morphologies： plate-like and bush-like. The XRD spectrum corresponds to the side planes of the ZnO nanorods made up of the nanoflowers. The micro-Raman spectrum of the ZnO nanoflowers exhibits the E2 （high） mode and the second order multiple-phonon mode. The photoluminescence spectrum of the ZnO nanoflowers exhibits ultraviolet emission centred at 375nm and a broad green emission centred at 526 nm.

Comparison between Dual Radio Frequency- and Pulse-Driven Sheath near Insulating Substrates

We carry out a comparison between the characteristics of radio frequency- and pulse-sheath near insulating substrates driven by dual frequency （DF） sources making use of the fluid model in which the self-bias voltage on the electrode is obtained consistently under a current balance condition. The results show that the combination of the higher and lower frequency source modulate the characteristics of the radio-frequency- and pulse-sheath： the higher frequency makes the physical quantities oscillate fast while the slow oscillating contour of variation in physical quantities is modulated by the lower frequency source. However, there are some differences between the capacity of mitigating the charging effects on the surface of the insulator, i.e., the pulsed driven plasma gains an advantage over the radio-frequency driven one because the insulating surface to neutralize the positive charge the ＇off＇ state of the pulse allow more electrons to reach due to the incident ion as the pulse being in the pulse＇s duty. In addition, the ion energy distribution （IED） bombarding the surface of the insulator has a range of energy for the radio-frequency bias while that for the pulse bias is discontinuous.

Plasmon-Assisted Phase-Matched Second- and Third-Harmonic Generation in Single-Negative Heterostructures

Dispersion relations of surface plasmon polaritons （SPPs） in sandwiched optical systems are studied. The system is actually a kind of SPP waveguides, with two kinds of single negative material （SNG） as core and cladding layers, respectively. Since both TM and TE polarized SPPs can be excited in the structure, the dispersion of SPPs becomes more abundant and leads to colorful nonlinear opticM properties. The authors demonstrate the effective phase-matched second and third-harmonic generation （SHG, THG） assisted by the coupled SPPs. A cascaded second-order nonlinear process can Mso be achieved in the structure when the thickness of the core layer is properly selected, leading to the simultaneous SHG and THG. Further investigations show that much easier phase-matching can be fulfilled in the SNG waveguide array. Our results would be of potential use for surface-enhanced frequency conversion device such as light emitters or lasers.

Shell Correction and Pairing Energies in the Dinuclear System Model

We investigate the dependences of the potential energy surfaces （PES） and the fusion probabilities for some cold fusion reactions leading to super-heavy elements on the nuclear shell effect and pairing energy. It is found that the shell effect plays an important role in the fusion of the super-heavy element while pairing energy＇s contribution is insignificant. The fusion probabilities and evaporation residue cross sections as functions of the Ge-isotope projectile bombarding ^208Pb are also investigated. It is found that evaporation residue cross sections do not always increase with the increasing neutron number of Ge-isotope.

Characteristics of Photonic Bandgap Fibres with Hollow Core＇s Inner Surface Coated by a Layer Material

Hollow core＇s inner surface coating in a photonic bandgap fibre （PBCF） is investigated by means of finite element method. The coat material and thickness-dependence dispersion curve and group velocity dispersion are numerically studied. The coating with materials of low index or small thickness will rise up the dispersion curve but will not induce surface modes. However, coating with materials of high index or big coat thickness will induce surface modes and avoided-crossings. By varying coat material＇s refractive index and thickness, the appearances of surface modes and avoided-crossings can be changed. It is found that the avoided-crossing can enormously enlarge the negative dispersion which can find applications in dispersion compensation. We numerically achieve a negative dispersion as large as -21416.15ps/nm/km. The results give a physical insight into the propagation properties of PBGFs with the hollow core coated by a layer of material and are of crucial significance in the applications of PBGF coating.

Design of Broadband Single Fundamental Mode Hollow Core Bragg Fibre

The condition of the single fundamental mode （HE11） transmission in hollow core Bragg fibres is investigated theoretically by the transfer matrix method. The influences of core size and cladding parameters on the single HE11 mode bandwidth are analysed, showing that the maximal bandwidth is more sensitive to the core size than the cladding. The numerical results show that sufficiently broad bandwidth of single HE11 mode transmission can be achieved by proper fibre design. A simple and fast method based on improved hollow metal waveguide model is proposed to optimize fibre structure parameters for the maximal single HE11 mode bandwidth.

On Kaup and Newell＇s Method for Solving DNLS Equation

Kaup and Newell＇s revised inverse scattering transform for the derivative nonlinear Schrodinger （DNLS） equation is investigated. We compared it with a more reasonable approach proposed recently, which is rigorously proven by the Liouville theorem. It is conduded that Kanp and Newell＇s revision is only suitable for giving single-soliton solution and can not be generalized to multi-soliton case.

Influence of Different Interlayers on Growth Mode and Properties of InN by MOVPE

We grow InN epilayers on different interlayers by metal organic vapour phase epitaxy （MOVPE） method, and investigate the effect of interlayer on the properties and growth mode of InN films. Three InN samples were deposited on nitrided sapphire, low-temperature InN （LT-InN） and high-temperature GaN （HT-GaN）, respectively. The InN layer grown directly on nitrided sapphire owns the narrowest x-ray diffraction rocking curve （XRC） width of 300 aresee among the three samples, and demonstrates a two-dimensional （2D） step-flow-like lateral growth mode, which is much different from the three-dimensional （3D） pillar-like growth mode of LT-InN and HT-GaN buffered samples. It seems that mismatch tensile strain is helpful for the lateral epitaxy of InN film, whereas compressive strain promotes the vertical growth of InN films.

Controllable Photonic Band Gap and Defect Mode in a 1D CO2-Laser Optical Lattice

We propose a new method to form a novel controfiable photonic crystal with cold atoms and study the photonic band gap （PBG） of an infinite 1D CO2-laser optical lattice of SSRb atoms under the condition of quantum coherence. A significant gap generated near the resonant frequency of the atom is founded and its dependence on physical parameters is also discussed. Using the eigenquation of defect mode, we calculate the defect mode when a defect is introduced into such a lattice. Our study shows that the proposed new method can be used to optically probe optical lattice in situ and to design some novel and controllable photonic crystals.

PIV Measurements and Mechanisms of Adjacent Synthetic Jets Interactions

Interactions of adjacent synthetic jet actuators with varying relative amplitude and the relative phase of driving voltage are measured using a particle image velocimetry （PIV）. Varying relative amplitude or relative phase of driving voltage of the adjacent actuators vectors the direction of the ensuing merged jet of the adjacent synthetic jets. The vectoring mechanism of the adjacent vortex pairs, attract-impact causing deflection （AICD）, is provided to explain why the merged jet is generally vectored to the side of the phase-leading synthetic jet or the synthetic jet with higher driving voltage.

Classical Study of Transfer and Ionization in A^2＋＋He Collisions

A simple model for the direct ionization and transfer ionization probabilities in A^2＋＋He collisions in a wide projectile energy range is proposed based on the Bohr-Lindhard model and the classical statistical model. The calculated cross sections are in satisfactory agreement with the experimental data available.

High Power Continuous-Wave and Acousto-Optic Q-Switched Nd：GdVO4 Laser Operated at 912 nm

We present a high power and efficient operation of the ^4F3/2 → ^4I9/2 transition in Nd：GdVO4 at 912nm. In the cw mode, the maximum output power of 8.6 W is achieved when the incident pump power is 40.3 W, leading to a slope efficiency of 33.3% and an optical-optical efficiency of 21.3%. To the best of our knowledge, this is the highest cw laser power at 912nm obtained with the conventional Nd：GdVO4 crystal. Pulsed operation of 912nm laser has also been realized by inserting a small aeousto-optie （A-O） Q-Switch inside the resonator. As a result, the minimal pulse width of 20ns and the average laser power 1.43 W at the repetition rate of lOkHz are obtained, corresponding to 7.1 kW peak power. We believe that this is the highest laser peak power at 912nm. Furthermore, duration of 65ns has also been acquired when the repetition rate is 100 kHz.