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An improved method for rockbolt fracture is proposed in this paper to determine the exact fracture position of rockbolts simulated using cable structural elements (cableSELs) in FLAC3D. This method employs the total elongation of the free segment of the rockbolt as the fracture criterion. The maximum deformation position is identified by comparing the length of each cableSEL in the free segment, leading to the fracture. The simulation results validated through a rockbolt tensile test closely match actual conditions. The proposed method was used to optimize the roadway support in deep extra-thick coal seams (DECSs). Optimized parameters were obtained by simulating and analyzing different lengths and spacings of rockbolts and anchor cables. The field implementation conducted shows that the optimized deformation and support strength of the roadway meet safety needs. [ABSTRACT FROM AUTHOR]

Combining a strong second‐order nonlinear optical (NLO) effect (>1×KH2PO4 (KDP)), a large band gap (>4.2 eV), and a moderate birefringence in ultraviolet (UV) NLO crystals remains a formidable challenge. Herein, Cd(SCN)2(C4H6N2)2, the first example of a thiocyanate capable of realizing a phase‐matched UV NLO crystal material, is obtained by reducing the sulfur (S) content in the centrosymmetric (CS) structure of Cd(SCN)2(CH4N2S)2. Compared to the "shoulder‐to‐shoulder" one‐dimensional (1D) chain of Cd(SCN)2(CH4N2S)2, Cd(SCN)2(C4H6N2)2 has a different sawtooth 1D chain structure. Cd(SCN)2(CH4N2S)2 has second harmonic generation (SHG) inertia with a band gap of 3.90 eV and a UV cutoff edge of 342 nm, however, it possesses a large birefringence (0.35@546 nm). In contrast, the symmetry center breaking of Cd(SCN)2(C4H6N2)2 leads to remarkably strong SHG intensity (10 times that of KDP). Furthermore, it has a wide band gap (4.74 eV), short UV cutoff edge (234 nm), and moderate birefringence capable of phase matching (0.17@546 nm). This research indicates that thiocyanates are a promising class of UV NLO crystal materials, and that modulation of the sulfur content of CS thiocyanates is an effective strategy for the development of UV NLO crystals with excellent overall performances. [ABSTRACT FROM AUTHOR]

The safety production pressure in coal mines is huge, and there is a general phenomenon of over-supporting in roadways. Even hard and dense thick limestone roofs do not dare to be unsupported. 1102 track roadways of Qiuji Coal Mine is taken as the engineering background, by constructing a hard roof deformation analysis model, quantifying the role of the fifth layer limestone thickness in controlling roadway deformation, using numerical simulation to verify theoretical calculation results, using field test and monitoring reinspection research results. The research shows that as the thickness of limestone increases, the roof deformation decreases continuously and the self-stability of the roadway increases. When the thickness of the fifth layer limestone reaches 1.5 m, the deformation of the roof is reduced by 77.4% compared with the thickness of 0.2 m, and the plastic zone is reduced by 40.5%. The thickness of the fifth layer of limestone in 1102 track roadway is greater than 1.5 m. The scheme of without supporting in the roadway roof and the anchor net supporting on both sides of the roadway is adopted. The results show that the vertical convergence of the roadway is extremely small, and the convergence on both sides of the roadway is less than 15 mm. The cables on both sides of the roadway are under stable force. The roof force measuring bolt (cable) does not rise but falls back after applying the pre-tightening force and no cracks and separation can be seen in the roof peep to meet the safety requirements.

The skeletal ring expansion of heteroarenes through carbene insertion is gaining popularity in synthetic chemistry. Efficient strategies for heterocyclic ring expansion to access heterocycles containing a fluoroalkyl quaternary carbon center through fluoroalkyl carbene insertion are highly desirable because of their broad applications in medicinal chemistry. Herein, we report a general strategy for the dearomative one‐carbon insertion of azoles using fluoroalkyl N‐triftosylhydrazones as fluoroalkyl carbene precursors, resulting in ring‐expanded heterocycles in excellent yields with good functional‐group compatibility. The broad generality of this methodology in the late‐stage diversification of pharmaceutically interesting bioactive molecules and versatile transformations of the products has been demonstrated. [ABSTRACT FROM AUTHOR]

Take the background of hard roof support problem of Qiuji Coal Mine 1102 working face haulageway, the cantilever beam model of uncutting roadway roof and the deformation and stress model of gob-side entry retaining are established. The maximum cantilever length of roadway roof cantilever beam structure is 4.68 m by theoretical calculation; the support resistance of the roadway roof with unit length suspended is 166.74 kN. Based on this, the parameters of roadway are designed, the specification of constant resistance and large deformation anchor cable is determined as ?准17.8 mm × 10 300 mm, and the spacing of two columns of anchor cable to be 1 000 mm and 2 000 mm respectively, and the roadway mine pressure is monitored. Monitoring results show that: within the range of 75 m to 173 m from the open-cut hole in 1102 haulageway, the maximum displacement of roadway roof and floor is about 36 mm, the roof abscission layer occurs at the junction of mudstone and limestone, the accumulative amount of abscission layer amount is 25 mm, the maximum stress of roof anchor cable is 150 kN, both deformation and stress are within a safe range, meet the stability requirement of roadway.