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Despite their high specific capacity and low cost, small-molecule organic cathodes usually suffer from fast capacity decay due to unavoidable dissolution in electrolytes, which largely impedes their practical applications. To resolve the above-mentioned issues, an in situ ionothermal synthesis strategy is proposed to prepare a C3N5 polymer matrix with azo groups using 2,4,6-tris(hydrazino)-s-triazine (TH) as the precursor for confining active small molecules to enhance the electrochemical stability. Herein, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) are used as exemplary molecules to demonstrate this strategy. Consequently, among optimized composites, PTTH-3 delivers the highest reversible capacity of 170 mA h g−1 at 0.1 A g−1, best rate capability (142 mA h g−1 at 1 A g−1 and 83 mA h g−1 at 20 A g−1) and the most excellent cycling stability with a capacity retention of 97.5% after 2000 cycles at 1 A g−1, better than all previously reported PTCDA cathodes. Additionally, NTTH-3 also shows far better electrochemical properties with a capacity retention of 84% after 2200 cycles at 1 A g−1 than NTCDA alone, indicative of the universality of this strategy. This method may pave the way for the practical application of high-capacity small molecular compounds in electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Coal mining produces a large amount of gangue that pollutes the environment, causing surface subsidence and damaging the groundwater systems. Backfill mining is an effective technology used to solve this problem, but there is a risk of polluting the groundwater due to the heavy metal ions present in the backfill material. Pb2+ has been determined to be a representative element because of its existence in coal gangue samples but not in fly ash. The risk of gangue-based cemented backfill causing groundwater pollution can be evaluated by studying the Pb2+ leaching from gangue under various conditions. When comparing the leaching amounts of Pb2+ from the coal gangue particles and the test blocks, it was found that cement filling has an obvious consolidation effect on the Pb2+ in coal gangue. The above process shows that cemented backfill has an obvious consolidation effect on the Pb2+ in gangue. The results of the theoretical analysis, X-ray, and SEM show that the consolidation mechanism can be divided into four modes: physical encapsulation, ion exchange, ion adsorption, and chemical reaction. The results are of great significance for revealing the leaching mechanism of the heavy metals in coal gangue, assessing the risk of heavy metal pollution in groundwater via gangue-cemented backfill, and improving the mining theory of the gangue-cemented filling and groundwater protection. [ABSTRACT FROM AUTHOR]

The power series polynomial constraining method is proposed in this paper. The dynamical model of the cantilever plate can be established by applying the constraint, which is different from the traditional polynomial. Firstly, the characteristic orthogonal polynomial was used to describe the displacement field of the rectangular plate of which all edges are free. Then the four-sided free plate was equivalent to cantilever plate by power series multiplier constraint method. The characteristic equation of the constructed cantilever plate was obtained by the Rayleigh–Ritz method. Natural frequencies and modal shapes of the plate were obtained by solving the characteristic equation. Next, the proposed method was adopted to establish dynamical model of a pair of solar panels clamped on the central platform symmetrically. The convergence of the proposed method was verified by comparing the calculated results of the cantilever plate with that of the finite element software ANSYS 15.0. The optimum order the power series polynomial was obtained by comparing different results. The analysis of the dynamical characteristics of the cantilever plate and the spacecraft demonstrates the validation of the proposed method. This method can provide a new idea for the plate with local edge constrained. [ABSTRACT FROM AUTHOR]

Previous studies have shown that dependency distance and its probability distribution can be applied as syntactic indicators of English as interlanguage. However, the universal application of these indicators has not been verified from the perspective of language typology. The issues are addressed in the present study based on a treebank of Chinese interlanguage of English and Japanese native speakers. The findings are as follows: (1) with the improvement of L2 proficiency, the MDDs of learners with different native language backgrounds gradually approach that of the target language in different patterns, and dependency distance is of universal significance as a metric to measure the development of interlanguage's syntactic complexity; (2) Chinese interlanguage also follows the principle of least effort, and its probability distribution of dependency distance, like those of natural languages, presents a power–law distribution, which can successfully fit the Zipf-Alekseev distribution; (3) the right truncated modified Zipf-Alekseev distribution can be used to measure Chinese interlanguage proficiency, and the fitting parameters of the probability distribution of dependency distance as a metric of interlanguage proficiency are also of universal value. [ABSTRACT FROM AUTHOR]

This paper presents the stability and bifurcation analysis of a simply-supported functionally graded materials (FGMs) rectangular plate subject to the transversal and in-plane excitations. A two-degree-of-freedom nonlinear system of the FGM plate is obtained via the Hamilton’s principle and the Galerkin approach. The case of primary parametric resonance and 1:2 internal resonance is considered. The asymptotic perturbation method is utilized to obtain four-dimensional nonlinear averaged equation. With the aid of Matlab and normal form theory, the various types of dynamical behavior in the neighborhood of a kind of degenerated equilibrium point are investigated. It was found that static bifurcation and Hopf bifurcation exist for the FGM rectangular plate under certain conditions.