We generalize Visser ’s method to construct traversable Lorentzian wormholes from surgically modified Friedman-Robertson-Walker spacetimes in both Brans-Dicke’s theory and induced theory of Gravity. Our result shows, in both cases, the exotic matter is unavoidable to occur at the throats of the wormholes.

A method which directs trajectories to the predetermined continuous target orbits in the system described by nonlinear differential equations with perturbation of available system parameters and the conditions for achieving targeting is given. The target orbits may be the unstable solution or even may not be the solution of the system. Numerical experiments are given in the periodically forced Brusselator.

The nucleon's tensor charges (isovector g^v_T = δu - δd and isoscalar g^s_T = δu + δd) are calculated using the QCD (quantum chromodynamics) sum rules in the presence of an external tensor field. By combining the mass sum rule of nucleon, we derive a simplified form for proton tensor charges, which gives g^v_T = 1.27 and g^s_T = 1.31, or δu = 1.29 and δd = 0.02 at the scale of nucleon mass, with an uncertainty about 20%.

By using triaxial-particle-rotor model with a perturbation term, ΔI = 2 staggering effects in the γ-transition energies of superdeformed bands built upon j_15/2 orbitals are investigated. The general features of ΔI = 2 staggering which have been observed are obtained in the calculations. The model provides a possibility to fit the calculated values to the experimental data.

A new nuclide ²³⁹Pa was produced by 50MeV/u ^l8O bombardment of natural uranium via multi-nucleon transfer reactions (²³⁸U-lp+2n). Protactinium was chemically separated from the uranium target and other produced elements. Then in that chemical fraction the growth and decay of ²³⁹U gamma rays were observed, identifying the ²³⁹U parent as ²³⁹Pa. Subsequent to ²³⁹Pa β^- decay, with a half-life of 106±30min, gamma rays of 522.0, 562.0, 638.5 and 681.0keV were also observed.

A new approach of the study on the spin-orbit components of resonant satellite photoionization has been carried out from many-body perturbation theory. The 3d⁸ 4s² (¹G, ³F,¹D) satellite lines of atomic Cu are resonantly enhanced and separated by the spin-orbit splitting at the energy of the 3p⁶3d¹⁰4s → 3p5 (² P_1/2, ² P_3/2) 3d¹⁰ 4s² transitions. The calculated results showing that the spin-orbit splitting leads to the separation of resonant peaks of satellite lines are in good agreement with experiment.

We here combine the eigenchannel theory and R-matrix theory to calculate the eigenchannel parameters of multichannel quantum defect theory directly. There are two advantages: (1) an analytical unified treatment of perturbed discrete Rydberg states, autoionizing states and their adjacent continuum to avoid numerical calculations, outside the R-matrix box; (2) clear assignment of overlapped resonances.

We present a scheme to realize a photon switch for controlling the state of the field in a cavity between a coherent state and a Schrödinger cat state. In the scheme, an atom crosses two cavities continually. The atom is resonant with the first cavity mode, and off-resonant with the second cavity mode. The detection of the atomic state leaves the two cavity modes in an entangled state. We can determine whether the second cavity field is in a coherent state or in a Schrödinger cat state via the detection of the photon in the first cavity.

An x-ray laser shadowgraphy experiment was conducted on Xingguang-II laser facility in 1996. A multi-layer spherical mirror was used as an imaging element and a high sensitivity CCD camera as a detector. We measured the near-field image of the Ti x-ray laser beam. With a Ti x-ray laser beam as a backlight source, we obtained a clear CU mesh image, demonstrating the potential as advanced diagnostic measurements to study high density plasmas in inertial confinement fusion research.

It is shown that, when two coherent waves are obliquely incident to a one-dimensional nonlinear optical superlattice containing Kerr-form dielectric nonlinearity, an incident-dependent two-dimensional nonlinear optical superlattice can be constructed. This structure can be bistable. There exist two types of optical bistable mechanism, i. e., the index-modulation mechanism and distributed feedback mechanism. Owing to the index-modulation mechanism, the threshold for the bistability is lower than that of a more traditional one-dimensional distributed feedback structure.

Two hysteresis loops and tristable states in an electron cyclotron resonance plasma system have been observed and oscillatory waveforms and their power spectra in different stable state are described in this paper. As the microwave power was increased, the oscillation with original fundamental frequency gradually transferred to harmonic frequencies and then sudden jumped to a regular oscillation with single fourth harmonic frequency.

The effects of electron-phonon interaction have to be taken into account for the physical process in a small system of condensed matters. The electron-phonon interaction in a I-D finite lattice system has been analyzed. The relation between the electron-phonon interaction and the symmetric properties of electronic states and phonons are considered, the transition probabilities are discussed.

The experimental evidences of a nearly single-crystalline diamond film, which was prepared by high temperature heteroepitaxial growth method, have been shown by scanning electron microscopy, transmission electron diffraction and x-ray double crystal diffraction methods.

Magneto-impedance (MI) effects have been observed in amorphous and nanocrystalline Fe_73.5CuNb₃Si_13.5B₉ ribbons. Large MI values have been obtained in nanocrystalline samples (NCS), but not in as-quenched samples (AQS). The magnetic responses of impedance of nanocrystalline samples share some common features with that of Co-based amorphous wire and ribbon samples. The field dependencies of effective permeability for nanocrystalline samples have shown a sharp change at the anisotropy field. The effective permeability and the hysteresis loops for AQS and NCS have been shown to be responsible for their MI effects. The sensitivity of the magnetic responses in the nanocrystalline sample can reach 50%/Oe.

The studies of Mössbauer spectroscopy and magnetic properties for complex Fe(tpa)(NCS)₂ exhibit that low spin → high spin (HS) transition may be thermally induced. The impurities such as HS-Fe²⁺ residue and HS-Fe³⁺, that were caused by compound preparation, play a significant role in the investigation of spin transition curve. The Mössbauer spectroscopy is used to observe the impurities as separated forms from the spin transition phase directly, and the magnetic susceptibility measurement is used to determine the total paramagnetism from all HS phases. With these two useful tools, an exact spin transition curve was defined by removing the magnetic contribution of the impurities.

The perovskite-like SrBi₂Ta₂O₉ (SBT) thin films have been fabricated on Si/SiO₂/Ti/Pt substrate by pulse laser deposition. The crystallization and ferroelectric property were clearly dependent on the annealing time and temperature. The SBT thin film with fine grain size and well-saturated square hysteresis loop was obtained after annealing at 750°C for 90min. Good ferroelectric properties were obtained from the SBT film annealed under this condition; P_r and E_c were 8.4μC/cm² and 57kV/cm, respectively.

The fundamental reflectivity spectra of Hg_0.8Cd_0.2Te have been investigated. The feature of the spectra is the presence of E_l and E₂ peaks within the fundamental absorption region. A three dimensional saddle point is used to fit the E_l and E_l+ Δ_l critical point and some simulated calculation is done for E₂ at X point. The measured and calculated reflectivities are compared and prominent features of the reflectivity spectra are identified with critical point transition at the and X points in the Brillouin zone.

Bright blue polymer light-emitting diodes have been fabricated by using the poly(pphenylenevinylene)-based copolymers with 10 C long aliphatic chains as the electroluminescent layers, PBD in PMMA and Alq₃ as the electron-transporting layers, and aluminum as the cathode. The multilayer structure devices show 190cd/m² light-emitting brightness at 460nm, 15 V turn-on vol- tage. It is found that the intensities of photoluminescence and electroluminescence (EL) increase with increasing aliphatic chain length, the EL intensity and operation stability of these polymer light-emitting diodes can be improved by reasonable design of the structure.

Blue emission from polymer blends composed of poly (2,5-dibutoxyphenyiene) (PPP) in a matrix polymer poly (N-vinylcarbazole) (PVK) is reported. The light-emitting layer can be fabricated by spin-coating of PPP-PVK blend solution without subsequent processing or heat treatment. A cell structure of glass substrate /indium-tin-oxide /PPP-PVK blend/aluminum is employed. Blue light emission with a peak position at 448nm occurs at a bias of about 8V.

We chose xylene C₈H₁₀ as carbon source instead of conventional methane CH₄ to fabricate a-Si_l-xC_x: H films using plasma-enhanced chemial vapour deposition method. The optical band gap of this material could be widened to 3.1eV. And the infrared absorption spectra of our films manifest the existence of aromatic ring in them. Strong blue light emission with a peak wavelength of 490nm has been observed at room temperature.

A liquid encapsulated melt zone process has been developed for single crystal growth of GaAs. Single crystals of 40mm long have been grown with this technique. To avoid unwanted nucleation events and maintain a constant crystal diameter, from top to bottom growth using a short zone with a convex zone surface was found to give the best results. An arsenic overpressure way used to in conjunction with a B₂O₃ encapsulant in order to suppress arsenic dissociation from the melt and maintain the stoichiometry of the crystal.

The capacity of short-term memory has been studied using an integrate-and-fire neuronal network model. It is found that the storage of events depend on the manner of the correlation between the events, and the capacity is dominated by the value of after-depolarization potential. There is a monotonic increasing relationship between the value of after-depolarization potential and the memory, numbers. The biophysics relevance of the network model is discussed and different kinds of the information processes are studied too.

By using the first, second and third electronic burst and transcient source experiment catalogs, a joint analysis of spatial and temporal distributions and hardness ratios of gamma-ray bursts is performed. Turning point features at C_max/C_min ~ 6 are found. This probably indicates the existence of two components of burster population which have distinct spatial distributions.