[en] Based on the empirical electron theory (EET) of solids and molecules, the valence-electron structures (VESs) of the main phases in Ti(C, N)-based cermets were calculated, and the relationship between the VES and properties was determined. The results indicated that the hardness of the phases with the same crystal structure could be compared using the covalent electron pairs, n_a, values on the strongest bonds and the plasticity by the sum of n_a values for the covalent bonds. The dissolution of N in TiC phase could improve the plasticity of TiC phase, and Mo, W and V dissolution could reduce its plasticity. However, Cr dissolution in the rim phase improved the plasticity of the rim phase, which should be advantageous for strengthening Ti(C, N)-based cermets. Based on those results, a Ti(C, N)-based cermet added with Cr₃C₂ was manufactured; the new cermet had more than twice the transverse rupture strength of a typical cermet

[en] The ESR spectra of radicals induced by γ-irradiation in pig bone have been studied and compared with those of UV-irradiated and unirradiated samples. An ESR signal which is specific for irradiation has been found. The signal height increased linearly with the increase of dose within the range of 1.23 to 6.24 kGy. When the samples were stored at room temperature and -18 degree as well as in the presence of air for 45 days and 22 days respectively, the growth of signal height has been also observed

[en] In order to overcome the randomness, abrasive waste and hydration layer of free abrasive polishing, a technology of bounded abrasive polishing for fused silica glass under anhydrous environment is proposed. A stable polishing wheel sintering process has been developed and applied to the polishing of fused silica glass. EDS energy spectrum analysis and XRD analysis of the processed products and the polishing wheel powder are carried out. The removal mechanism of consolidation abrasive polishing is preliminarily elaborated, and the effect of pressure and speed on the removal efficiency and surface roughness is explored from the macroscopic point of view. The experimental results show that: in the process, under normal force and shear force, the CeO₂ abrasive reacts with the fused silica, CeO₂ will bring SiO₂ out of the glass, thus to achieve material removal; at the same time, influence of pressure and rotating speed on the processing efficiency does not follow the Preston formula, temperature rise and chip removal of the polishing wheel are the key factors determining the efficiency of removal. (authors)

[en] The emergence of intense synchrotron X-ray sources, efficient focusing optics and high-performance X-ray sensitive area detectors allows for measurements of diffuse scattering from cubic micron-scale sample volumes. Here we present an experiment that illustrates methods for studying the local structure and defect content of tiny sample volumes. In the experiment, an X-ray microbeam illuminating about ∼5 (micro)m³ of a Ni-based superalloy single crystal, is used to collect Laue patterns and reciprocal space volume maps around fundamental and a superstructure reflections. This measurement illustrates how diffuse reciprocal-space distributions can be collected with good spatial and momentum-transfer resolution from a tiny real-space sample volume. This example demonstrates that emerging diffuse scattering techniques can provide fundamentally new information about crystallographic organization and defect content over many length scales.

[en] A nonlinear Schroedinger equation with varying dispersion, nonlinearity and gain (or absorption) is studied for ultrashort optical pulses propagating in inhomogeneous optical fibres in the case of normal dispersion. Using the modified Hirota method and symbolic computation, the bilinear form and analytic soliton solution are derived. Stable bright and dark solitons are observed in the normal dispersion regime. A periodically varying soliton and compressed soliton without any fluctuation are obtained. Combined and kink-shaped solitons are observed. Possibly applicable soliton control techniques, which are used to design dispersion-managed systems, are proposed. The proposed techniques may find applications in soliton management communication links, soliton compression and soliton control. (solitons)

[en] A simple standard reaction-diffusion (RD) model assumes an infinite oxide thickness and a zero initial interface trap density, which is not the case in real MOS devices. In this paper, we numerically solve the RD model by taking into account the finite oxide thickness and an initial trap density. The results show that trap generation/passivation as a function of stress/recovery time is strongly affected by the condition of the gate-oxide/poly-Si boundary. When an absorbent boundary is considered, the RD model is more consistent with the measured interface-trap data from CMOS devices under bias temperature stress. The results also show that non-negligible initial traps should affect the power index n when a power law of the trap generation with the stress time, tⁿ, is observed in the diffusion limited region of the RD model.

[en] The development of high-performance photocatalysts is central to efforts focused on taking advantage of solar energy to overcome environmental and energy crises. Integrating different functional materials artfully into nanostructures can deliver more efficient photocatalytic activity. Here, sandwiched ZnO@Au@CdS nanorod films were synthesized via successive ZnO nanorod electrodeposition, Au sputtering and CdS electrodeposition. The as-synthesized composites were characterized by UV–vis spectrophotometer, x-ray diffractometer, scanning and transmission electron microscopy. Their photocatalytic activity was assessed by degrading Rhodamine B solution under visible light irradiation. ZnO@Au@CdS exhibited better photocatalytic performance than ZnO@CdS throughout the visible light region, and the corresponding enhancement factor of Au nanoparticles was measured as a function of CdS loading amount, and it could reach 190% with CdS deposition for 1 min. The normalized rate constant could reach 0.387 h⁻¹ for ZnO@Au@CdS-1min, which was equivalent to or better than results in reference photocatalysts. The enhancement mechanism of Au nanoparticles was estimated by comparing the monochromatic photocatalytic action spectra with the absorption spectrum of ZnO@Au@CdS, and it was mainly determined by incident photon energy. With selective excitation of Au nanoparticles by incident photons, the excited hot electrons in Au NPs are transferred to the conduction band of ZnO to boost photocatalytic reaction. With selective excitation of CdS, the enhanced interband absorption of CdS and relay station effect of Au nanoparticles should be responsible for the enhanced photocatalytic performance. Our work not only opens the door to the design of efficient supported photocatalysts, but also helps to understand the enhancement mechanism of LSPR effect on the photoelectric conversion of semiconductors. (paper)

[en] In this paper, two types of the (2+1)-dimensional breaking soliton equations are investigated, which describe the interactions of the Riemann waves with the long waves. With symbolic computation, the Hirota bilinear forms and Baecklund transformations are derived for those two systems. Furthermore, multisoliton solutions in terms of the Wronskian determinant are constructed, which are verified through the direct substitution of the solutions into the bilinear equations. Via the Wronskian technique, it is proved that the Baecklund transformations obtained are the ones between the (N - 1)- and N-soliton solutions. Propagations and interactions of the kink-/bell-shaped solitons are presented. It is shown that the Riemann waves possess the solitonic properties, and maintain the amplitudes and velocities in the collisions only with some phase shifts. (general)

[en] The pulse amplification in the dispersion-decreasing fiber (DDF) is investigated via symbolic computation to solve the variable-coefficient higher-order nonlinear Schroedinger equation with the effects of third-order dispersion, self-steepening, and stimulated Raman scattering. The analytic one-soliton solution of this model is obtained with a set of parametric conditions. Based on this solution, the fundamental soliton is shown to be amplified in the DDF. The comparison of the amplitude of pulses for different dispersion profiles of the DDF is also performed through the graphical analysis. The results of this paper would be of certain value to the study of signal amplification and pulse compression. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

[en] Under investigation in this paper are two coupled integrable dispersionless (CID) equations modeling the dynamics of the current-fed string within an external magnetic field. Through a set of the dependent variable transformations, the bilinear forms for the CID equations are derived. Based on the Hirota method and symbolic computation, the analytic N-soliton solutions are presented. Infinitely many conservation laws for the CID equations are given through the known spectral problem. Propagation characteristics and interaction behaviors of the solitons are analyzed graphically. (general)