[en] 0.95(Na_0.96-xK_xLi_0.04)(Nb_0.89Sb_0.07Ta_0.04)O₃ - 0.05KNbO₃ (abbreviated as K_xNLNST-KN, x = 0.32 - 0.52) lead-free piezoelectric ceramics were prepared by using the conventional solid-state sintering method, and the intentional addition of a pre-calcined KNbO₃ powder was used as a sintering aid that might inhibit and compensate for the volatilization of alkali metals during the sintering process. The preparation of the ceramics and the effects of K/Na ratio on the structure and the electrical properties of these ceramics were studied in detail. Compared with the relatively higher sintering temperature of Li-, Sb-, and Ta-modified KNN ceramics reported in the literature, the dense ceramic samples were obtained at a reduced temperature of 1060 .deg. C, and the ceramics with x = 0.44 possessed optimal properties: d₃₃ = 298 pC/N, k_p = 48%, P_r = 21.9 μC/cm², and E_c = 11.5 kV/cm.

[en] Based on the small-gain theorem, the anti-synchronization between two identical new hyperchaotic systems is investigated, moreover, the general sufficient conditions to achieve anti-synchronization between the new hyperchaotic system and the new hyperchaotic Lorenz system are obtained via small-gain theorem. Numerical simulations are performed to verify and illustrate the analytical results. (general)

[en] This article discussed the topic of specific inspection about γ irradiator facility in radiation safety and protection, provided suggestions for the further inspection and management. (authors)

[en] Quantum metrology holds the promise of improving the measurement precision beyond the limit of classical approaches. To achieve such enhancement in performance requires the development of quantum estimation theories as well as novel experimental techniques. In this article, we provide a brief review of some recent results in the field of quantum metrology. We emphasize that the unambiguous demonstration of the quantum-enhanced precision needs a careful analysis of the resources involved. In particular, the implementation of quantum metrology in practice requires us to take into account the experimental imperfections included, for example, particle loss and dephasing noise. For a detailed introduction to the experimental demonstrations of quantum metrology, we refer the reader to another article ‘Quantum metrology’ in the same issue. (topical review - quantum information)

[en] The transportation system promotes the development of the metropolitan area, while the number of vehicles in the transportation system is increasing, and the speed of energy consumption is also increasing. The consequences are not only the destruction of human living environment, but also many urban problems such as traffic congestion and urban environmental pollution for people living in the metropolitan area. In order to solve these problems, the article proposes a design scheme for urban public transport from the perspective of energy conservation. Through the modular design method, combined with the existing electric vehicle drive technology, the public transport is divided into two modules: the ride module and the drive module; at the same time, the existing traffic information service system is integrated to construct service system of the information guide to support the public transport scheme. The public transport design provides a possible solution to environmental pollution and traffic congestion. (paper)

[en] Objective: To investigate the effects of the different levels of ¹³¹I and ⁹⁹Tc^m background in the body on bone mineral density (BMD) measurement in dual energy X-ray absorptiometry (DXA). Methods: To compare the BMDs before and 3 h after oral ¹³¹I 370 kBq and 3, 24 h after intravenous injection of ⁹⁹Tc^mO₄^- 185 MBq. The BMDs of the forearm, lumbar vertebrae 2-4 (L_2-4), right femoral neck, Ward's triangle of 35 subjects were measured four times (before and after the administration of the two radioactive tracers using the thyroid imaging) by Sophos-XRA instrument made in France. The results were defined as ¹³¹I 3 h, ⁹⁹Tc^m 3, 24 h group and control group. Results: As compared with the control group, the BMD of L_2-3, Ward's triangle in ⁹⁹Tc^m 3 h group were significantly increased by 13.2%, 6.2%, 10.7% (P<0.05). The increase of BMD of Ward's triangle was positively correlated with the counts of background (r=0.870, P<0.01). The order of the increases of BMDs was L₂, Ward's triangle, L₃. There was no significant difference among the BMDs of forearm, neck and L₄ in ⁹⁹Tc^m 3 h group and all BMDs in ⁹⁹Tc^m 24 h, ¹³¹I 3 h group and control group (P>0.05). Conclusion: The accuracy of BMD in DXA is effected by ⁹⁹Tc^m for thyroid imaging, but not by ¹³¹I for routine thyroid uptake test

[en] Micro-machining is the most effective method for KDP crystal to mitigate the surface damage growth in high power laser systems. In this work, spherical and Gaussian mitigation pits are fabricated by micro-milling with an efficient machining procedure. The light intensification caused by front-surface features after mitigation is numerically modeled based on the finite element method (FEM) for acquiring the optimal structural parameters of mitigation pits. The results indicate that the occurrence of diffraction from the pits is principally responsible for the light intensification inside the crystal, and the interference from the second incident laser on the pit's fringe results in the light intensification, which unsteady increases with the decreasing of the pit's wide-depth ratio. For spherical and Gaussian pits after mitigation, it is suggested that the width-depth ratio of spherical mitigation pit should be devised to be larger than 5.0 to avoid the second incident light, achieving the minimal light intensification for the mitigation of surface damage growth. When the wide-depth ratio of the mitigation pit is larger than 10.0, Gaussian contour is preferred to achieve better repairing quality. The laser damage test on the mitigation pits with 1000 μm-width and 20 μm-depth has effectively verified the simulation results. (authors)

[en] Fracture near the U10Mo/cladding material interface impacts fuel service life. In this work, a mesoscale stress model is developed with the fuel foil considered as a porous medium having gas bubbles and bearing bubble pressure and surface tension. The models for the evolution of bubble volume fraction, size and internal pressure are also obtained. For a U10Mo/Al monolithic fuel plate under location-dependent irradiation, the finite element simulation of the thermo-mechanical coupling behavior is implemented to obtain the bubble distribution and evolution behavior together with their effects on the mesoscale stresses. The numerical simulation results indicate that higher macroscale tensile stresses appear close to the locations with the maximum increments of fuel foil thickness, which is intensively related to irradiation creep deformations. The maximum mesoscale tensile stress is more than 2 times of the macroscale one on the irradiation time of 98 days, which results from the contributions of considerable volume fraction and internal pressure of bubbles. This study lays a foundation for the fracture mechanism analysis and development of a fracture criterion for U10Mo monolithic fuels

[en] Highlights: • It proves that the relationship between porosity and spacer content was linear based on theory and practice, that is P = aS_c + b. This model equation can be applicable for the methods that the pores of foams were created by removing a fugitive material. • It indicates that the volumetric change rate of pores (V_R) is a constant and its value altered in different preparing conditions. • Mechanical properties of a foam material can also be predicted by spacer content when using the space holder technique. - Abstract: Titanium foam has been obtained more and more attention due to its combination with porous structure and titanium. The space holder technique was widely used to fabricate this kind of material because of its low cost, easy operation and freely controllable pore structure and properties. However, how to obtain the desired porosities has been a big challenge for this technique, because they are always not equal to the expected ones. Hence, the relationship between porosity (P) and spacer content (S_c) was studied based on theory and practice in this paper. The results show that the relationship between porosity and spacer content was linear, that is P = aS_c + b. It indicates that the volumetric change rate of pores (V_R) is a constant and its value altered in different preparing conditions. Through the research of this paper, the porosity and mechanical properties of a foam material can be predicted by spacer content.

[en] Secondary structures of RNAs are the basis of understanding their tertiary structures and functions and so their predictions are widely needed due to increasing discovery of noncoding RNAs. In the last decades, a lot of methods have been proposed to predict RNA secondary structures but their accuracies encountered bottleneck. Here we present a method for RNA secondary structure prediction using direct coupling analysis and a remove-and-expand algorithm that shows better performance than four existing popular multiple-sequence methods. We further show that the results can also be used to improve the prediction accuracy of the single-sequence methods. (special topic)