We report an extraordinary sound absorption enhancement in low and intermediate frequencies achieved by a thin multi-slit hybrid structure formed by incorporating micrometer scale micro-slits into a sub-millimeter scale meso-slit matrix. Theoretical and numerical results reveal that this exotic phenomenon is attributed to the noticeable velocity and temperature gradients induced at the junctures of the micro- and meso-slits, which cause significant loss of sound energy as a result of viscous and thermal effects. It is demonstrated that the proposed thin multi-slit hybrid structure with micro-scale configuration is capable of controling low frequency noise with large wavelength, which is attractive for applications where the size and weight of a sound absorber are restricted.

We discuss, in terms of a simple model, the spin wave excitations, spontaneous magnetization and response to alternating fields of magnetic superlattices.

We report the superconductivity in iron-based oxyarsenide Sm[O_1-xF_x]FeAs, with the onset resistivity transition temperature at 55.0K and Meissner transition at 54.6K. This compound has the same crystal structure as LaOFeAs with shrunk crystal lattices, and becomes the superconductor with the highest critical temperature among all materials besides copper oxides up to now.

Mo_1-xGe_x, Mo_1-xSi_x, films were prepared by getter sputtering onto liquid nitrogen cooled substrates. The amorphous phase formations were Ge > 22 at . % , Si > 18 at .% respectively. With the increase of Ge, Si content, Tc decreased from 6 to 3K in the amorphous state. The measured results of (dB_c2/dT)T_c , J_c and ρ( 300K) /ρ(8K) indicated that the four chosen Mo_1-xSi_x films exhibit fundamental characteristics of amorphous superconductors.

The structure function for the deep–inelastic scattering of electrons on He, Be, Al, Fe and Au are analysed. It is found that all these structure functions satisfy a kind of scale relation, and the scale parameter ξ_A in creases logarithmically with the nucleon number A.

The high resolution laser spectroscopy study on the l(2, -1) type Coriolis resonance in CH₃Fv₅ R_QO and p_p3 was carried out. An improved value of E₅ is obtained, E₅=2.3892(9) x10^-3cm^-1.

Different α-nucleus potentials for the anomalous large angle scattering have been tested by the ⁴⁰Ca (α, P ) reaction. It seems that the WS ( squared Woods-Saxon ) , WS^2.65 and WS⁵ potential can not provide a correct description of the behaviour of the incident α channel wave functions, but with the L-dependent potential a reasonable result can be obtained.

We derive a unified multi-harmonic modulation solution of the incommensurate phase with a simple model by a method like that used in solving pendulum problems in mechanics. This solution reduces to single-harmonic modulation at the upper end of temperatures, and transforms into kink solution at the lower end of temperatures, The basic wave-vector decreases monotonically with temperature, as was observed in experimentation.

An extended ratio method is applied to some lattice models. We find the following interesting features: the extended method often appears to be smoother and better; the odd-even oscillations are reduced greatly; and the Neville tables often provide sequences with faster convergence rate.

The energy dispersive relation of surface dangling bond state on InP (ī ī ī) clear, surface has been measured bg the angle resolved photo-mission. The theoretical calculation based on a slab model and extended Hückel theory agreed well with the experimental result if a surface relaxed atomic structure model for InP (ī ī ī) (1x1) is postulated.

We report high transition temperature superconductivity in one unit-cell (UC) thick FeSe films grown on a Se-etched SrTiO₃(001) substrate by molecular beam epitaxy (MBE). A superconducting gap as large as 20 meV and the magnetic field induced vortex state revealed by in situ scanning tunneling microscopy (STM) suggest that the superconductivity of the 1 UC FeSe films could occur around 77 K. The control transport measurement shows that the onset superconductivity temperature is well above 50 K. Our work not only demonstrates a powerful way for finding new superconductors and for raising T_C, but also provides a well-defined platform for systematic studies of the mechanism of unconventional superconductivity by using different superconducting materials and substrates.

An intrinsic magnetic topological insulator (TI) is a stoichiometric magnetic compound possessing both inherent magnetic order and topological electronic states. Such a material can provide a shortcut to various novel topological quantum effects but remained elusive experimentally for a long time. Here we report the experimental realization of thin films of an intrinsic magnetic TI, MnBi$_{2}$Te$_{4}$, by alternate growth of a Bi$_{2}$Te$_{3}$ quintuple layer and a MnTe bilayer with molecular beam epitaxy. The material shows the archetypical Dirac surface states in angle-resolved photoemission spectroscopy and is demonstrated to be an antiferromagnetic topological insulator with ferromagnetic surfaces by magnetic and transport measurements as well as first-principles calculations. The unique magnetic and topological electronic structures and their interplays enable the material to embody rich quantum phases such as quantum anomalous Hall insulators and axion insulators at higher temperature and in a well-controlled way.

Based on dislocation theory, we investigate the mechanism of strain rate effect. Strain rate effect and dislocation motion are bridged by Orowan's relationship, and the stress dependence of dislocation velocity is considered as the dynamics relationship of dislocation motion. The mechanism of strain rate effect is then investigated qualitatively by using these two relationships although the kinematics relationship of dislocation motion is absent due to complicated styles of dislocation motion. The process of strain rate effect is interpreted and some details of strain rate effect are adequately discussed. The present analyses agree with the existing experimental results. Based on the analyses, we propose that strain rate criteria rather than stress criteria should be satisfied when a metal is fully yielded at a given strain rate.

Using the extremely sharp peak of backward cross section for polarized γ+e → H+e processes one could hopefully detect Higgs bosons in W-S model.

The periodic and chaotic behaviors for both long and short delay time are demonstrated successfully using a hybrid OBD. The degree of stability S is introduced into the dynamic equations of optical bistability with a delayed feedback. The instability threshold is S=2 for long delay time and S=l+π/2Q for short delay time.

By measuring the temperature of the crystallization front of salol by means of in situ observations on a thermally regulating stage, we have obtained the linear form of (T_S/L-T_M.B),i.e., the difference between the temperatures of the front and the melt block vs v, the solidified volume of the interface per second.

A formula of the critical temperature for superconductors with small λ is derived from the Eliashberg equation.

A comparison between the electron captures of ¹⁵⁸Tb and ¹⁵⁷Tb is presented. The practical merit of using ¹⁵⁷Tb electron capture rates as a tool for electron-neutrino mass determination is analysed and emphasized.

We attempt to discover some exact analytical models of the spherically symmetric spacetime of collapsing fluid under shearfree conditions. Two types of solution are considered: one is to impose a condition on the mass function, while the other is to restrict the pressure. We obtain five exact models in total, and some of them satisfy the Darmois conditions.

Initial flow stress in tension and tension plus compression and coercivity after those processes in dual-phase steels have been measured. It was found that the values of coercivity for tension plus compression are smaller than for pure tension, a phenomenon much like the Bauschinger effect in steels.

We investigate the detailed epidemic spreading process in scale-free networks with link weights that denote familiarity between two individuals. It is found that the spreading velocity reaches a peak quickly then decays in a power-law form. Numerical study exhibits that the nodes with larger strength is preferential to be infected, but the hierarchical dynamics are not clearly found, which is different from the well-known result in the unweighed network case. In addition, also by numerical study, we demonstrate that larger dispersion of weight of networks results in slower spreading, which indicates that epidemic spreads more quickly on unweighted scale-free networks than on weighted scale-free networks with the same condition.

The modified simple equation method is employed to construct the exact solutions involving parameters of nonlinear evolution equations via the (1+1)-dimensional modified KdV equation, and the (1+1)-dimensional reaction-diffusion equation. When these parameters are taken to be special values, the solitary wave solutions are derived from the exact solutions. It is shown that the proposed method provides a more powerful mathematical tool for solving nonlinear evolution equations in mathematical physics.

High resolution angle-resolved photoemission measurements have been carried out to study the superconducting gap in the (Ba_0.6K_0.4)Fe₂As₂ superconductor with T_c=35 K. Two hole-like Fermi surface sheets around the Γ point exhibit different superconducting gaps. The inner Fermi surface sheet shows larger (10~12 meV) and slightly momentum-dependent gap while the outer one has smaller (7~8meV) and nearly isotropic gap. The lack of gap node in both Fermi surface sheets favours s-wave superconducting gap symmetry. Superconducting gap opening is also observed at the M(π,π) point. The two Fermi surface spots near the M point are gapped below T_c but the gap persists above T_c. The rich and detailed superconducting gap information will provide key insights and constraints in understanding pairing mechanism in the iron-based superconductors.

Undoped and copper doped zinc oxide (ZnO) thin films have been prepared on glass substrates by spray pyrolysis technique. The films were doped with copper using the direct method by addition of a copper salt (CuCl₂) in the spray solution of ZnO. Variation of structural, electrical, optical and thermoluminescence (TL) properties with doping concentrations is investigated in detail.

Using the adaptive time-dependent density-matrix renormalization group method, the dynamics of entanglement and quantum discord of an one-dimensional spin-1/2 XXZ chain is studied when anisotropic interaction quenches are applied at different temperatures. The dynamics of the quantum discord and pairwise entanglement between the nearest qubits shows that the entanglement and quantum discord will first oscillate and then approach to a constant value. The quantum discord can be used to predict the quantum phase transition, while the entanglement cannot.

We report a new kagome quantum spin liquid candidate Cu$_3$Zn(OH)$_6$FBr, which does not experience any phase transition down to 50 mK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature ($\sim$200 K). A clear gap opening at low temperature is observed in the uniform spin susceptibility obtained from $^{19}$F nuclear magnetic resonance measurements. We observe the characteristic magnetic field dependence of the gap as expected for fractionalized spin-1/2 spinon excitations. Our experimental results provide firm evidence for spin fractionalization in a topologically ordered spin system, resembling charge fractionalization in the fractional quantum Hall state.

The differential cross sections of ¹⁷F and ¹⁷O elastic scattering products on ²⁰⁸Pb have been measured at the Radioactive Ion Beam Line at Lanzhou (RIBLL). Two angular dispersion plots of ln(dσ/dθ) versus θ² are obtained from the angular distribution of the elastic scattering differential cross sections. The angular dispersion plot exhibits a clear turning point for ¹⁷F in the range of small scattering angles 6--20° due to its exotic structure, but for ¹⁷O, the turning point is not observed in the same angular range. The experimental results have been compared with previous data of other groups. Systematical analysis on the available data supports the above conclusion that there is an exotic behaviour of the angular dispersion plot of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the turning point of the angular dispersion plot appears at small angle for weakly bound nuclei with halo or skin structure, and can be used as a new probe to investigate the halo and skin phenomena of weakly bound nuclei.

The one-dimensional nonlinear Schrödinger equation with a perturbation of polynomial type is considered. Using the approximate symmetry perturbation theory, the approximate symmetries and approximate symmetry reduction equations are obtained.

General dynamical networks with distributed time delays are studied. The topology of the networks are viewed as unknown parameters, which need to be identified. Some auxiliary systems (also called the network estimators) are designed to achieve this goal. Both linear feedback control and adaptive strategy are applied in designing these network estimators. Based on linear matrix inequalities and the Lyapunov function method, the sufficient condition for the achievement of topology identification is obtained. This method can also better monitor the switching topology of dynamical networks. Illustrative examples are provided to show the effectiveness of this method.

A series of layered (Sr_1-xK_x)Fe₂As₂ compounds with nominal x=0--0.40 are synthesized by solid state reaction method. Similar to other parent compounds of iron-based pnictide superconductors, pure SrFe₂As₂ shows a strong resistivity anomaly near 210 K, which was ascribed to the spin-density-wave instability. The anomaly temperature is much higher than those observed in LaOFeAs and BaFe₂As₂, the two prototype parent compounds with ZrCuSiAs- and ThCr₂Si₂-type structures. K-doping strongly suppresses this anomaly and induces superconductivity. Like in the case of K-doped BaFe₂As₂, sharp superconducting transitions at T_c38K is observed. We perform the Hall coefficient measurement, and confirm that the dominant carriers are hole-type. The carrier density is enhanced by a factor of 3 in comparison to F-doped LaOFeAs superconductor.