For a nonholonomic mechanics system with the action of small disturbance, the Lie symmetrical perturbation and adiabatic invariants of generalized Hojman type are studied under general infinitesimal transformations of groups in which the generalized coordinates and timeare variable. On the basis of the invariance of disturbed nonholonomic dynamical equations under general infinitesimal transformations, the determining equations, the constrained restriction equations and the additional restriction equations of Lie symmetries of the system are constructed, which only depend on the variables t, q_{s} and ^{.}q^{s}. Based on the definition of higher-order adiabatic invariants of a mechanical system, the perturbation of Lie symmetries for a nonholonomic system with the action of small disturbance is investigated, and the Lie symmetrical adiabatic invariants, the weakly Lie symmetrical adiabatic invariants and the strongly Lie symmetrical adiabatic invariants of generalized Hojman type of disturbed nonholonomic systems are obtained. An example is given to illustrate applications of the results.

The solutions, in terms of orthogonal polynomials, of Dirac equation with analytically solvable potentials are investigated within a novel formalism by transforming the relativistic equation into a Schrodinger-like one. Earlier results are discussed in a unified framework, and some solutions of a large class of potentials are given.

We derive a formula that simplifies the original asymptotic iteration method formulation to find the energy eigenvalues for the analytically solvable cases. We then show that there is a connection between the asymptotic iteration and the Nikiforov--Uvarov methods, which both solve the second order linear ordinary differential equations analytically.

A determinantal formula is developed for direct evaluation of transition amplitude without solving the wave equation in a one-dimensional potential scattering system. Our formulation is based on the principle that a desired quantity can be extracted from the wave operator, which is the master operator maintaining all the information of the system. This principle is tested in a simplified system, i.e., in a one-dimensional potential scattering system. We are now developing a formula for direct evaluation of near-field amplitude to design a system, in which local field enhancement is desired.

Bell's theorem without inequalities is applied for some general Greenberger--Horn--Zeilinger (GHZ) states and W states and a wide range of such states can exhibit all-versus-nothing conflict between local realism and quantum theory. The case of standard GHZ state is contained in our proposal. For some generalized GHZ states more intensive violation on local realism is manifested.

The minimal quantization structure is employed to investigate the quantum version of the Stackelberg duopoly with continuous distributed asymmetric information, i.e. the first mover has incomplete information that obeys a continuous distribution while the second mover has complete information. It is found that the effects of the positive quantum entanglement on the outcomes exhibit many interesting features due to the information asymmetry. Moreover, although the first-mover advantage is counteracted by the information asymmetry, the positive quantum entanglement still enhances the first-mover advantage and improves the first-mover tolerance of the information asymmetry beyond the classical limit.

We study the information transfer and entanglement transfer in a system consisting of single trapped ions in cavities by the three-mode cross-Kerr-like interaction among the cavity field (photons), the centre-of-mass motion (phonons) and the internal state of the trapped ion in the Lamb--Dicke and large detuning regime.

We present a series of universal quantum cloning machines for two identical mixed qubits. Every machine is optimal in the sense that it achieves the optimal bound of the single copy shrinking factor. Unlike in the case of pure state cloning, the single copy shrinking factor does not uniquely determine the cloning map in the case of mixed state cloning.

In this paper we propose a new scheme of long-distance quantum cryptography based on spin networks with qubits stored in electron spins of quantum dots. By conditional Faraday rotation, single photon polarization measurement, and quantum state transfer, maximal-entangled Bell states for quantum cryptography between two long-distance parties are created. Meanwhile, efficient quantum state transfer over arbitrary distances is obtained in a spin chain by a proper choice of coupling strengths and using spin memory technique improved. We also analyse the security of the scheme against the cloning-based attack which can be also implemented in spin network and discover that this spin network cloning coincides with the optimal fidelity achieved by an eavesdropper for entanglement-based cryptography.

We propose a scheme to prepare many two-mode cavities into one-dimensional cluster states in the context of cavity QED. The left-circularly polarized state and right-circularly polarized state of the cavity are encoded as the logic zero and one of the qubits. In the scheme, the atomic spontaneous emission is suppressed, and the fidelity is unaffected by the cavity decay on the assumption that the detection efficiencies of all the photondetectors are 1.

We find the most general tetrads which give a regular charged spacetime in tetrad theory of gravitation. The metric is a static one and it includes the Schwarzschild and Reissner Nordstrom black holes. The energy content contained in a sphere of radius R is calculated using the superpotential given by Moller in the context of Weitzenbock spacetime.

We investigate the geodetic precession of light in the Schwarzschild spacetime surrounded by quintessence. With the analysis and numerical methods, we find that the geodetic precession of light in the Schwarzschild spacetime surrounded by quintessence increases when the normalization factor c increases, and the geodetic precession decreases when the quintessential state parameter ω_{q }increases.

We investigate the noise-induced synchronization between two identical uncoupled Hodgkin--Huxley neurons with sinusoidal stimulations. The numerical results confirm that the value of critical noise intensity for synchronizing two systems is much less than the magnitude of mean size of the attractor in the original system, and the deterministic feature of the attractor in the original system remains unchanged. This finding is significantly different from the previous work [Phys. Rev. E 67 (2003) 027201] in which the value of the critical noise intensity for synchronizing two systems was found to be roughly equal to the magnitude of mean size of the attractor in the original system, and at this intensity, the noise swamps the qualitative structure of the attractor in the original deterministic systems to synchronize to their stochastic dynamics. Further investigation shows that the critical noise intensity for synchronizing two neurons induced by noise may be related to the structure of interspike intervals of the original systems.

We study the escape for the mean first passage time (MFPT) over a potential barrier for a system with non-fluctuating potential barrier and only driven by a three-state noise. It is shown that in some circumstances, the three-state noise can induce the resonant activation for the MFPT over the potential barrier; but in other circumstances, it can not. There are three resonant activations for the MFPT over the potential barrier, which are respectively as the functions of the transition rates of the three-state noise.

The time-delayed bistable system subjected to the multiplicative and additive noises is investigated. In the condition of small delay time, the stationary probability distribution function (SPDF) is derived, and under the condition of large delay time, the SPDF is stochastically simulated. The analytical and simulative results indicate that: (i) For the case of λ=0 (λ denotes the strength of correlations between the multiplicative and additive noises), the time delay affects weakly the SPDF peak structure, and the symmetrical property of the SPDF two-peak structure does not change with the increasing delay time. (ii) For the case of λ≠0, the two-peak structure changes with the increasing delay time, i.e. one peak goes up and the other go down simultaneously as the delay time increases and along with further increase of the delay time, the lower peak disappears gradually while the higher one goes up, i.e. the structure of the SPDF changes from a bimodal to a unimodal and the system becomes monostable.

Spatial chaos of a Bose--Einstein condensate perturbed by a weak laser standing wave and a weak laser δ pulse is studied. By using the perturbed chaotic solution we investigate the new type of Melnikov chaotic regions, which depend on an integration constant c_{0 }determined by the boundary conditions. It is shown that when the |c_{0}| values are small, the chaotic region corresponds to small values of laser wave vector k, and the chaotic region for the larger k values is related to the large |c_{0}| values. The result is confirmed numerically by finding the chaotic and regular orbits on the Poincaré section for the two different parameter regions. Thus, for a fixed c_{0} the adjustment of k from a small value to large value can transform the chaotic region into the regular one or on the contrary, which suggests a feasible method for eliminating or generating Melnikov chaos.

We theoretically analyse the temperature effects on a surface plasmon resonance (SPR) sensor in Kretschmann configuration. The temperature effects include the thermo-optic effect and the dispersion of thermal-optic coefficient in the dielectric along with the thermal expansion effect, phonon--electron scattering and electron--electron scattering in the metal layer. We simulate the temperature dependence of the resonance position and the sensitivity of the SPR sensor under wavelength-interrogation and angular-interrogation mode of operation and the differences are pointed out in the two modes.

We use a diamond anvil cell for the first time to investigate the Raman spectra of an aqueous micellar solution of hexadecyltrimethylammonium bromide (CTAB) at pressures up to 3.85GPa. The pressure-induced phase transition between the micellar and coagel phases is found to occur at 0.64GPa and 60°C. This phase transition has a pressure hysteresis, and thus exhibits the first-order phase transition properties. Further experimental results show that although the structure of the coagel phase is similar to that of the CTAB crystal, the interchain distance is slightly larger in the coagel phase than that in the CTAB crystal.

A volt--second (Vs) source intended for absolutely calibrating the integrator in a pulsed field magnetometer (PFM) is designed and proven to be with accurate rising and falling edges and reasonable lower uncertainty. A comparison experiment shows that the difference between the magnetic fluxes generated respectively by the Vs source and the mutual inductor is within ±0.04%. The PFM is then calibrated in an absolute way of the Vs source. The calibrated PFM gives the measured results in good agreement with a static BH tracer supplied by National Institute of Metrology of China and provides a convenient way of studying the effect of mathematic process on the dynamic measuring curve of PFMs.

We show that for the Green--Schwarz superstring on AdS_{5}i×S^{5}, the Cartan 1-forms associated with the flat currents given by Bena, Polchinski and Roiban [Phys. Rev. D 69(2004)046002] also satisfy equations of motion and the Virasoro constraint. Thus one can generate a series of classical solutions with a spectrum parameter from the existing one, and these solutions have the same infinite set of classically conserved quantities.

The global colour model at finite temperature is further extended to study the systems at finite chemical potential. The deconfinement and chiral phase transition at finite chemical potential and at temperature T=0K are studied simultaneously. Meanwhile the evolution of the bag constants at finite chemical potential is calculated. The dependences of results on the model parameters are discussed in detail.

Inserting the masses of some states, which have been established in the experiments or the theory of lattice QCD, we investigate the mass of the isodoublet of the 2^{3}S_{1} meson nonet. The agreement results, 1567±22.6MeV and 1576.8MeV, are given by two different approaches. We suggest that the assignment of 2^{3}S_{1} meson nonet should be re-examined in future experiments.

To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D(d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2K for beam energies ranging from 10 to 20keV. The thick target yields of protons emitted in the D(d,p) T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2K is deduced to be 520±56eV. As compared with the value achieved in the gas target, the calculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section σ(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2K are obtained, respectively.

We report the chemical etching behaviour of the CR-39 polymer detector exposed to fission fragments of ^{252}Cf describing etchability of latent tracks, which are like nanocylinders. The fission fragment exposed detectors were etched in 1--7N NaOH water solutions at temperatures 50--80°C for 45min in the case of track length and 180min in the case of track diameter measurements. The reduced etch rate S (called here etchability) is determined using experimental results for all etching conditions and the etching conditions with the highest reduced etch are obtained. Physics and energetics of bulk and track etching are discussed. Possible effects causing spurious changes in determination of activation energy of etching are investigated.

We show that two trains of half-cycle pulses (HCPs) with different amplitudes irradiating alternately on polar molecules can achieve a remarkable enhancement of field-free orientation compared with the case of an equal amplitude HCPs train for the same pulse separation. This kind of orientation enhancements is mainly due to an optimal adjustment of the population distribution on every field-free angular momentum eigenstate, in which the populations on the undesired states of high angular momenta are effectively suppressed, and the populations on the desired states of low angular momenta are correspondingly promoted.

The cross sections for neutralization and detachment in H^{+}--H^{-} collisions in the energy range from 1.0 to 100keV/u are calculated using the two-centre atomic orbital close-coupling (TC-AOCC) method. The results are compared with the available experimental and theoretical data. It is found that the neutralization cross section agrees well with the experimental data by Schon et al. [J. Phys. B 20 (1987) L759] and Melchert et al., [J. Phys. B 32 (1999) L139] especially at low energies. However, for the detachment process, our calculated cross section lies between the experimental data by Melchert et al. and by Peart et al. [J. Phys. B 9 (1976) 3047] for the energy below 15keV/u. Above this energy, our result is smaller than the two experimental data. It is worth pointing out that there exists a large difference between these two experimental data and it is difficult to judge which data is more accurate. Therefore, a high-precision measurement for detachment cross sections is expected to resolve this discrepancy and to test the theoretical calculations.

We present the results for resonances in positron--He scattering at low impact energy (19.3--24.0eV) by using the momentum space coupled-channel optical (CCO) method. The S-partial wave resonance at 20.16eV is found for the first time.

Total cross sections in positron--Mg collision are calculated in the range 2.0--60.0eV using the momentum space coupled channels optical potential approach. The target ionization continuum and the positronium formation are included in the optical potential. The present total cross sections are compared with the experiment data and the other theoretical results.

We present a simplified formulae system describing the polarization properties of the quantum cyclotron radiation by a nonrelativistic thermal electron in a very strong magnetic field. In this system, each of the derived quantities, including the Einstein coefficients, the absorption cross sections, and scattering cross sections, as well as the absorption coefficients by plasma, is divided into the perpendicularly and parallelly polarized components. The results, especially the absorption and scattering cross sections of resonant frequency photons, are potentially important in x-ray and gamma-ray astronomy, particularly in the study of gamma-ray bursts and pulsars.

We propose a deviation model and study the influences of the relative error and sensitivity of a machine on the transmission coefficients (TCs) of Fibonacci superlattices. It is found that for a system with fewer layers, the influence of deviation can be ignored. When superlattices become more complicated, they may be fabricated by a machine with suitable relative error and possess the designed value of TC. However, when the number of system layers exceeds some critical value, superlattices should be manufactured only by precise machines. The influence of the sensitivity is also discussed.

Due to many experimental data required and a lot of calculations involved, it is very complex and cumbersome to model prism-based liquid-refractive-index-measuring methods. We develop a new method of mathematical modelling for measuring refractive index of a liquid based upon the Fresnel formula and prism internal reflection at an incident angle less than the critical angle. With this method, only two different concentrations measurements for a kind of solution can lead to the determination of computational model. Measurements are performed to examine the validity of the theoretical model. Experimental results indicate the feasibility of the theoretical model with an error of 1%. The method is also capable of measuring even smaller changes in the optical refractive index of the material on a metal surface by the surface plasma resonance sensing techniques.

The spontaneous emission (SE) progress of polarized atoms in a stratified structure of air--dielectric(D0)--metal(M)--dielectric(D1)--air can be controlled effectively by changing the thickness of the D1 layer and rotating the polarized direction of atoms. It is found that the normalized SE rate of atoms located inside the D0 layer crucially depends on the atomic position and the thickness of the D1 layer. When the atom is located near the D0--M interface, the normalized atomic SE rate as a function of the atomic position is abruptly onset for the thin D1 layer. However, with the increasing thickness of the D1 layer, the corresponding curve profile exhibits plateau and stays nearly unchanged. The substantial change of the SE rate stems from the excitation of the surface plasmon polaritons in metal-dielectric interface, and the feature crucially depends on the thickness of D1 layer. If atoms are positioned near the D0--air interface, the substantial variation of the normalized SE rate appears when rotating the polarized direction of atoms. These findings manifest that the atomic SE processes can be flexibly controlled by altering the thickness of the dielectric layer D1 or rotating the orientation of the polarization of atoms.

Birefringence-Zeeman dual frequency lasers are capable of producing frequency difference from several kilohertz to hundreds of megahertz, but the precision of giving and stabilizing of the beat frequency still needs improvement to the range of ±200kHz. We design a new elastic force-exerting device comprised of the bottom part, two arms and two pieces of force-exerting sheets. The frequency difference smoothly tuning is realized with this device in a large range of 2MHz to 20MHz. Power-balance frequency stabilization system is used to investigate characters of the temperature, frequency difference and laser power. The precision of the frequency difference has reach up to ±100kHz after system temperature balance. Analyses of the laser frequency difference and power character are carried out.

A novel fibre ring laser is proposed and successfully demonstrated. By cascading a tunable bandpass filter with a bandstop filter to construct the desired narrow dual-transmission-peak spectrum, and employing a segment of unpumped erbium-doped fibre as a saturable absorber, a stable fibre ring laser is achieved at room temperature. The proposed laser can operate in dual-wavelength with the wavelength spacing of 0.48nm and the extinction ratio more than 50dB or switch between the two wavelengths by adjusting a polarization controller. The stability is investigated experimentally and explained theoretically.

We report a diode-pumped intracavity frequency-doubled self-Q-switched and mode-locked Cr,Nd:YAG/KTP green laser with a Z-type cavity, which produces 1.5W of average power at 532nm with incident pump power 14.2W. The individual mode-locked green pulse duration is about 560ps with 149MHz repetition rate. Almost 100% modulation depth of the mode-locked green pulses is achieved at an incident pump power of 4.13W. The maximum energy of Q-switched green pulse is 19.8μJ. The experimental results of pulse duration and pulse energy of Q-switched green pulse agree well with the theoretical calculations.

Room-temperature operation terahertz (THz) wave source is demonstrated using three MgO:LiNbO_{3} crystals which have a noncollinear arrangement. The experimental results show that the THz wave can be tunable from 0.8THz to 3.0THz, and the peak energy output is 103pJ/pulse at 1.5THz. The noncollinear cavity configuration makes the THz beam have Gaussian-like spatial distribution, small divergence angle, perpendicularly eradiated from the crystal surface. The beam quality factor M^{2} is measured to be M_{x}^{2}=1.15, M_{z}^{2}=1.25 for characterizing the THz wave beam. Experiments also show that the THz beam can be focused by using a polyethylene lens, and the focal spot size is close to the diffraction limit.

We report an efficient nanosecond optical parametric generator (OPG) with a periodically-phase-reversed periodically poled MgO:LiNbO_{3}(ppr-PPMgLN), which produces two pairs of signal and idler waves. The OPG is pumped by a 1.064μm Q-switched Nd:YVO_{4 }laser. When the repetition rate is set at 10kHz, the maximum average total output power of 570mW is achieved, including 410mW of dual-signal radiations and 160mW of dual-idler radiations. The total conversion efficiency is 32.5%. The tunable dual-signal wavelengths in the range of 1.474--1.518μm and 1.490--1.539μm and the dual-idler of 3.826--3.558μm and 3.726--3.451μm are obtained by changing the crystal temperature from 30°C to 200μC.

A new ternary photopolymer system is used in fabricating photonic crystals (PhCs) with controlled defects by combination of single-photon and two-photon photopolymerization. The former process can produce PhCs in one-step recording with a low-power (tens mW) continuous-wave laser at 532nm, while the latter can create desired defects. The preparation of the material, the optical setup and the preliminary experimental results are given. Compared with other methods, this approach is much more accessible and convenient for use of visible light and has advantages of making PhCs in a large scale quickly and economically and introducing any defects exactly, especially for three-dimensional structures.

Two-photon photopolymerization (TPP) of femtosecond laser is a promising method to fabricate three-dimensional woodpile photonic crystals (PCs). We build micro-fabrication system based on the principle of TPP. Three-dimensional woodpile PCs consisting of in-plane rod distances ranging from 1000nm to 2000nm are fabricated by focusing femtosecond laser in photosensitive liquid resin ORMOCER. The properties of the PCs are also discussed, and fundamental photonic band gaps in middle-infrared range are measured, whose in-plane rod distances are 1500nm and 2000nm. Three-dimensional woodpile PC devices with desired defects, such as cross-waveguide and micro-laser structures, are introduced easily by TPP. We fabricate the three-dimensional woodpile PCs in the liquid resin at the fast scanning speed of 120μm/s.

We study the transmission of one-dimensional photonic crystals consisting of single-negative permittivity and single-negative permeability media by using transfer matrix method. A pair of transmission modes is found in the gap. The transmission modes are dependent only on the ratio of the thicknesses of the two alternating layers. The separation of a pair of transmission modes can be tuned by varying the thickness of the defect layer or the ratio of thicknesses of the two alternating layers.

We propose a Mach--Zehnder interferometer (MZI) based on coupled dielectric pillars. It is composed of single-row pillar coupled waveguide modulating arms and three-row pillar waveguide 3dB couplers. The slow light property and transmission loss of the single-row pillar modulating arm are optimized by the plane wave expansion method. A short 3dB coupler is designed based on the modes transformation in three-row pillar waveguide. Finite difference time domain simulations prove the validity of this MZI and show that it has low insertion loss of <1.1dB and high extinction ratio of >12dB.

A self-similar mode locked fibre laser is studied based on a numerical model. By introducing a dimensionless factor k to characterize the pulse shape, the self-similar pulse evolution, formation and the temporal and spectral shape changes due to the elements in the cavity are investigated throughout the laser cavity. The results show that in the self-similar mode locked fibre laser, self-similar pulse is first formed in the single-mode fibre, which is then amplified in the gain fibre. Gain bandwidth has a small influence on pulse shape, so high energy self-similar pulse can be obtained after amplification. Because net cavity dispersion directly influences the pulse width as well as peak power after compression by a pair of gratings, which can determine the pulse self-similar evolution, it is very important to control the net cavity dispersion to a certain range to obtain self-similar pulses.

The perturbation method is employed to analyse the guided waves in a borehole surrounded by a cubic crystal medium for the first time. The cubic crystal medium is regarded as a reference unperturbed isotropic state added to the perturbation. The dispersion characteristics of Stoneley wave, pseudo-Rayleigh wave, flexural wave, and screw wave are investigated in detail. It is found that dispersion of the guided waves excited by monopole and dipole sources does not depend on the azimuth of the source, whereas the dispersion of screw wave excited by quadrupole source is significantly related to the azimuth of the source. Screw waves propagated along different azimuth in the borehole can be split. This is different from screw waves in transversely isotropic media (hexagonal crystal), which have been widely studied.

The wonderful performance of hearing systems is mainly attributed to the tuning filtering of basilar membrane (BM). Although theory of the cochlear mechanism has been greatly developed since the 1970s and the amplification or sensitivity of the cochlea has been concluded due to the out hair cells, the mechanics underlying the sharp-tuning or frequency selectivity of cochlea remains a puzzle. We use the cochlear translation function derived from the data of an experiment of the BM in vivo to calculate basilar responses to tone bursts, and find that there are resonant peaks with the characteristic frequency at the corresponding place in the initial and terminal part of the responses. However, when the translation function is shallower, there will be no resonant peaks in the responses. The result indicates that the sharp tuning is due to existence of the active resonant tuning mechanism.

As an advanced optical method, a multi-point pump method is presented for measurements of thermo-physical properties of liquids. Meanwhile, based on the laser-induced thermal grating method, a new theory model is presented and used to analyse the thermal effects caused by the multi-point laser pump, by which the thermal conductivity of liquids can be obtained. The results of some typical liquids, such as water, ethanol and acetone, are presented and are consistent with those of acknowledged values, demonstrating that the multi-point method is simple and useful for characterizing thermal properties of liquids.

Electron temperature, density, plasma potential and their fluctuation profiles at edge plasmas are measured simultaneously with a reciprocating probe system in HL-2A. The analysis results of four-tip data indicate that the temperature fluctuation has relative amplitude of 10--15%, gives more contribution to particle flux in lower (0--25kHz) and higher frequency (50--250kHz) ranges. The coherence between temperature fluctuations and density or potential fluctuations implies that their coupling will impact anomalous transport. The measured diffusion coefficient is about three times of the Bohm diffusion coefficient when considering the temperature fluctuation. The particle flux with temperature fluctuation is discussed in HL-2A for the first time.

Slide-away discharges are achieved by decreasing the plasma density or ramping down the plasma current in runaway discharges in the HT-7 tokamak. In the case of plasma current ramp down, the ratio of the electron plasma frequency to the electron cyclotron frequency is higher than in the stationary pulses when the discharge goes into a slide-away regime. The instability regime is characterized by relaxations in the electron cyclotron emission due to relativistic anomalous Doppler effect which transfers energy from parallel to perpendicular motion. The triggering of relativistic anomalous Doppler effect at higher density by ramping down of plasma current may provide a alternative runaway energy control scenario.

A 2.5-dimensional electromagnetic particle-in-cell (PIC) simulation code is used to investigate electron behaviour in collisionless magnetic reconnection. The results show that the ion/electron mass ratio (m_{i}/m_{e}) almost has no impact on the reconnection rate, however it can significantly affect electron behaviour in the diffusion region. For the case with larger mass ratio, the width of electron current sheet becomes smaller and the outflow region along the separatrix is smaller, hence the peak of the electron outflow speed is essentially larger. Density cavities and the parallel electric field E_{//} along the separatrix can be found in the case with larger mass ratio, which may have significant influences on the acceleration and heating of the electrons near the X point.

We perform an ab initio study on the electronic structure and charge density of the ε-oxygen under high pressure, which is obtained by powder x-ray diffraction experiment recently. Our results show that the hybridization among the σ_{g}*, π_{u} and π_{g}* bands in the ε-oxygen are not significant even at megabar pressure. Pressure-induced metallization occurs due to the band overlapping near the Fermi level at about 50GPa. A new network along the b-axis is formed and the O_{8} characteristic in the ε phase disappears above 50GPa even though the symmetry remains unchanged.

Depth sensing indentation (DSI) tests at the range of 200--1800mN are performed on porous sialon ceramic to determine the indentation load on Young's modulus and hardness values. The Young modulus and hardness (Dynamic and Martens) values are deduced by analysing the unloading segments of the DSI test load-displacement curves using the Oliver--Pharr method. It is found that Young's modulus E_{r}, the dynamic hardness H_{D} and the Martens hardness H_{M} exhibit significant indentation load dependences. The values of Young's modulus and hardness decrease with the increasing indentation load, as a result of indentation load effect. The experimental h_{f}/h_{m} ratios lower than the critical value 0.7, with h_{m} being the maximum penetration depth during loading and h_{f} the final unloading depth, indicate that our sample shows the work hardening behaviour.

Manipulating the directional movement of liquid droplets is of significance for design and fabrication of some microfluidic devices. An energy-based method is adopted to analyse the directional movement of a droplet deposited in a conical tube or on a conical fibre. We perform an experiment to investigate the directional motion of a droplet in an open conical tube. Our theoretical analysis and experimental observations both demonstrate that surface tension can drive the droplet to move in the conical tube. The critical condition of the liquid moving in the conical tube is presented. We also analyse a droplet on a conical hydrophilic fibre, which can move from the thinner to the thicker end.

Morphologies of Cu(111) films on Si(111)-7×7 surfaces prepared at low temperature are investigated by scanning tunnelling microscopy (STM) and reflection high-energy electron diffraction (RHEED). At the initial growth stage, Cu films are flat due to the formation of silicide at the interface that decreases the mismatch between Cu films and the Si substrate. Different from the usual multilayer growth of Cu/Cu(111), on the silicide layer a layer-by-layer growth is observed. The two dimensional (2D) growth is explained by the enhanced high island density at low deposition temperature. Increasing deposition rate produces films with different morphologies, which is the result of Ostwald ripening.

Electronic properties of both Pb and S vacancy defects in PbS(100) have been studied using the first-principles density functional theory (DFT) calculations with the plane-wave pseudopotentials. It is found that the density of states (DOS) near the top of the valence band and the bottom of the conduction band is significantly modified by these defects. Our calculation indicates that in the case of S vacancy defects the Fermi energy shifts to the conduction band making it as an n-type PbS (donor). However, in the case of Pb vacancy, because of the appreciable change of the DOS, the system acts as a p-type PbS (accepter). In addition, the structural relaxation shows that the defect leads to outward relaxation of the nearest-neighbouring atoms and inward relaxation of the next-nearest neighbouring atoms.

The ground-state energy and effective mass of an acoustic polaron in one dimension are calculated by using an electron--longitudinal-acoustic-phonon interaction Hamiltonian derived here. The self-trapping of the acoustic polaron is discussed. It is found that the critical coupling constant shifts toward weaker electron--phonon interaction with the increasing cutoff wave vector and the products of the critical coupling constant by the cutoff wave vector tend to a certain value. The self-trapping of acoustic polarons in one dimension is easier to be realized than that in three- and two-dimensional systems. The self-trapping transition of acoustic polarons is expected to be observed in the one dimensional systems of alkali halides and wide-band-gap semiconductors.

We analyse the transport properties of a coupled double quantum dot (DQD) device with one of the dots (QD1) coupled to metallic leads and the other (QD2) embedded in an Aharonov--Bhom (A-B) ring by means of the slave-boson mean-field theory. It is found that in this system, the Kondo resonance and the Fano interference exist simultaneously, the enhancing Kondo effect and the increasing hopping of the QD2-Ring destroy the localized electron state in the QD2 for the QD1-leads, and accordingly, the Fano interference between the DQD-leads and the QD1-leads are suppressed. Under some conditions, the Fano interference can be quenched fully and the single Kondo resonance of the QD1-leads comes into being. Moreover, when the magnetic flux of the A-B ring is zero, the influence of the parity of the A-B ring on the transport properties is very weak, but this influence becomes more obvious with non-zero magnetic flux. Thus this model may be a candidate for future device applications.

Electronic structures and magnetoresistance (MR) of Co_{3}Cu_{5} and Co_{3}Cu_{7} models as well as their interface atom exchange models Co_{2}CuCoCu_{4} and Co_{2}CuCoCu_{6} are investigated by the first-principles pseudopotential plane-wave method based on density functional theory. Charge transfer, magnetic moment, density of states, spin asymmetry factor, and MR ratio are discussed. The results show that the values of charge transfer and spin asymmetry factor at the Fermi level of Co layers are closely related to the neighbouring background of the Co layer. The Co layer with two sides adjacent to the Cu layer would transfer more charge to the Cu layer than other neighbouring background and have the largest spin asymmetry factor at the Fermi level. The Co layer with two neighbouring Co layers (interior Co) would gain a little charge and have the smallest spin asymmetry factor at the Fermi level. Two-current model is used to evaluate the MR ratio of Co_{2}CuCoCu__{4 }(Co_{2}CuCoCu_{6}) to be larger than that of Co_{3}Cu_{5} (Co_{3}Cu_{7}), which can be explained by the charge transfer and spin asymmetry factor.

We study the plasmon-assisted transmission of two kinds of slit structures in a 290-nm-thick silver film on a glass substrate. For the two-slit structure, the total transmission intensity spectra displays a complex modulation, which is attributed to different propagation constants of the surface plasmon polaritons (SPPs) on the silver-air and silver-glass interfaces. Replacing one of the two slits by a shallow corrugation results in a simple sinusoidal intensity modulation because of the only effective SPP excitation and propagation on the silver-air interface. These confirm the role of different SPP propagations and interference in the transmission properties of metal nanoslits.

The subband energy and lasing wavelength of compressively strained triangular In_{0.53}Ga_{0.47}As/InAs quantum well are calculated and compared with the conventional rectangular ones with the same strain contents. The strain compensation using Al_{0.33}In_{0.36}Ga_{0.31}As barrier is introduced. The results show that lasing wavelength can be extended dramatically to beyond 2.8μm by changing the energy band from the conventional rectangular shape to a triangular one, the realization of such a structure using molecular beam epitaxy technology is also discussed.

By introducing the entangled state representation and Feynman assumption that `electron pairs are bosons, ..., a bound pair acts as a Bose particle', we construct an operator Hamiltonian for a mesoscopic inductance-capacitance (LC) circuit including a Josephson junction, then we use the Heisenberg equation of motion to derive the current equation and the voltage equation across the inductance as well as across the Josephson junction. The result manifestly shows how the junction voltage is affected by the capacitance coupling. In this way the Cooper-pair number-phase quantization for this system is completed.

Electrical characteristics of In_{0.05}Ga_{0.95}N/Al_{0.07}Ga_{0.93}N and In_{0.05}Ga_{0.95}N/GaN multiple quantum well (MQW) ultraviolet light-emitting diodes (UV-LEDs) at 400nm wavelength are measured. It is found that for InGaN/AlGaN MQW LEDs, both ideality factor and parallel resistance are similar to those of InGaN/GaN MQW LEDs, while series resistance is two times larger. It is suggested that the Al_{0.07}Ga_{0.93}N barrier layer did not change crystal quality and electrical characteristic of p-n junction either, but brought larger series resistance. As a result, InGaN/AlGaN MQW LEDs suffer more serious thermal dissipation problem although they show higher light output efficiency.

A series of Ga doping perovskite cobaltite La_{2/3}Sr_{1/3}(Co_{1-y}Ga_{y})O_{3} (y=0, 0.1, 0.2, 0.3 and 0.4) are prepared by the standard solid-state reaction method. Their magnetic properties and Co ions spin state transitions are studied. Upon doping, no appreciable structure changes can be found. However, the corresponding Curie temperature sharply decreases and the magnetization is greatly reduced, indicating that Ga doping destroys the ferromagnetic interaction in the system. In addition, the high temperature magnetization data follow the Curie--Weiss law. At least one kind of Co ions (Co^{3+} or Co^{4+}) favours the mixed spin state, and most Co ions are at the lower spin state (low and intermediate state). With increasing Ga content, more Co ions transit to the higher spin state.

We investigate the electrical properties of the nanostructured magnetic colloid without and with magnetic field. The competition between the directional motion of the charged magnetic nanoparticles and other minor nonmagnetic impurities (also small amount of ions) under applied voltage and their random orientation due to thermal activation is implemented to elaborate the electrically conduction mechanism under zero magnetic field. Two equivalent electric circuits are employed for explaining the charging and discharging processes. The tunnelling conduction mechanism upon application of externally magnetic field may exist in the nanostructured magnetic colloid. The alternation of the two conduction mechanisms accounts for the current spikes when the magnetic field is switched on or off. This work presents the peculiar electrical phenomena of the magnetically colloidal system.

Lead-free piezoelectric ceramics 0.92(Bi_{0.5}Na_{0.5})TiO_{3}-0.08BaTiO_{3}+xmol% Co^{3+ }(BNBT-Co, x=0--8) are prepared by the solid state reaction method. Effects of the amount of Co^{3+} on the electrical properties and phase transition are studied. The results indicate that the addition of Co^{3+} enhances the mechanical quality factor Q_{m} significantly, whereas the dissipation factor tan δ has a minimum value at x=3.5. Meanwhile, addition of Co^{3+} leads to small decreases of piezoelectric constant d_{33}, and planar electromechanical coupling k_{p}. The present 0.92(Bi_{0.5}Na_{0.5})TiO_{3}-0.08BaTiO_{3}+3.5mol% Co^{3+} ceramics exhibit good performance with mechanical quality factor Q_{m}=910, piezoelectric constant d_{33}=106pC/N, planar electromechanical coupling k_{p}=10% and dissipation factor tanδ=1.1% at 1kHz. Saturated polarization hysteresis loops have been obtained for BNBT-Co ceramics. Two dielectric peaks at depolarization temperature T_{d} and T_{m} appear in the curves of ε^{T}_{33} vs temperature for the pure BNBT ceramics. However, the first dielectric peak T_{d} disappears after the addition of Co^{3+ }which means that the transition from ferroelectric to antiferroelectric phase has been eliminated.

Five InAs/In_{x}Ga_{1-x}As quantum dots in a well (DWELL) with different indium concentration x are grown by solid source molecular beam epitaxy. The high quantum dot density is observed in the InAs/In_{0.3}Ga_{0.7}As DWELL. The photoluminescence (PL) experiments indicate that the ground state peaks of InAs/In_{0.15}Ga_{0.85}As and InAs/In_{0.22}Ga_{0.78}As DWELLs shift to 1.31 and 1.33μm, respectively. The optical properties are investigated by using the PL and piezoreflectance spectroscope methods. An abnormal blue shift has been observed with the further increase of x from 0.22 to 0.30.

We design and prepare three-layer graded ZnO nanowhisker/polyester composites. The dispersion configuration of ZnO nanowhiskers in the polyester is investigated, and their microwave reflectivity curves are also measured. Experimental results have shown that the graded dispersion with ZnO nanowhiskers contributes to broadband microwave absorption. In other words, the absorption band depends on the graded dispersion configuration of ZnO nanowhiskers in polyester matrix.

Stressed by external forces, it is possible for a cylindric pipeline to change into an elliptic pipeline. To expose the effect of small shape change of the pipeline on the depletion interactions, both the depletion potentials and depletion forces in the hard sphere systems confined by a cylindric pipeline or by an elliptic pipeline are studied by Monte Carlo simulations. The numerical results show that the depletion interactions are strongly affected by the small change of the shape of the pipeline in a way. Furthermore, it is also found that the depletion interactions will be strengthened if the short axis of the elliptic pipeline is decreased.

Time-resolved mid-IR transient absorption spectroscopy is employed to explore the mechanism of improving the performance of dye-sensitized TiO_{2} solar cell (DSSC) when a certain amount of H_{2}O is added into the electrolyte. The relaxation kinetics of dye-sensitized TiO_{2} nanocrystalline film and the corresponding DSSC performance are investigated under different conditions. It is found that the interfacial charge recombination is retarded and electron injection efficiency is increased in the water vapour and in the electrolyte when D_{2}O is added. The values of open-circuit photovoltage V_{oc} and the short-circuit photocurrent J_{sc} of the cells are linearly correlated to the product of the two decay time constants. We also observed that V_{oc} well correlates with electron injection efficiency. It provides a preliminary microscopic account for the function of the added water in improving the performance of DSSCs.

Molecular dynamics simulations are performed for water confined in carbon nanotubes with various diameters (11.0--13.8AA). The simulations under an isobaric pressure (one atmosphere) by lowering temperatures from 300K to 190K are carried out. Water molecules within variously sized tubes tend to transform from disorder to order with different configurations (four-water-molecule ring, six-water-molecule ring and seven-water-molecule ring) at phase transition temperatures, which may be lowered by the increasing tube radius. It is also found that the configurations of water in (10, 10) tube are not unique (seven-molecule ring and seven-molecule ring plus water chain).

A rewritable polymer memory device based on gold nanoparticle doped poly (N-vinylcarbazole) (PVK), which can be easily fabricated by simple spin coating, has been described. An electrical bistable phenomenon is observed in the current-voltage characteristics of this device, and it is found that the electrical bistability is repeatable by proper writing voltage and erasing voltage. The unique behaviour of the devices provides an interesting approach such that doping nanoparticles in polymer can be used to realize high performance nonvolatile polymer memory devices.

We perform a theoretical study on a low dark current InGaAs/GaAs very-long-wavelength (>12μm) quantum well infrared photodetector (VLW-QWIP), based on a double barrier resonant tunnelling structure (DBRTS). The ground tunnelling state of the central quantum well (QW) of the DBRTS can resonate with the first excited bound state of the doped InGaAs QW by adjusting the structure parameters of the DBRTS. Investigation of the carrier transport performance of this device is carried out based on quantum wave transport theory. It has been shown that the dark current in this device can be significantly reduced by two orders compared to conventional InGaAs/GaAs VLW-QWIPs, while the photocurrent is almost the same as those in conventional VLW-QWIPs. This DBRTS integrated VLW-QWIP structure may stimulate the experimental investigation for VLW-QWIPs at high operation temperatures.

The quintessence contribution to a Schwarzschild black hole entropy is thoroughly investigated by using the improved brick-wall model. It is found that due to the present of the quintessence, there are two horizons, one is the cosmological horizon, and the other is the black hole horizon. By regulating the cut-off factor ε and the thickness of the thin layer δ, we obtain that the entropy of the system is 1/4 of the sum of the areas of the two event horizons.

The C-field cosmological model based on the Hoyle--Narlikar theory with variable gravitational constant G is investigated. To obtain the deterministic value of C=dC/dt we present certain constant values for integration constants. The creation field is proportional to time. G and ρ (density) decrease with time and the universe represents an expanding universe. The creation field increases as time increases. We find C=√{1/(2πf)}t where f>0. Thus C=1 when f=1/(2π)>0.