Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism...Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident stimulus.Secondly, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.展开更多
Tricho-dento-osseous(TDO)syndrome is a rare autosomal dominant disease resulting from distal-less homeobox 3(DLX3)mutation.1,2 Accumulative bone density in alveolar bone is a clinically favorable phenotype for TDO pat...Tricho-dento-osseous(TDO)syndrome is a rare autosomal dominant disease resulting from distal-less homeobox 3(DLX3)mutation.1,2 Accumulative bone density in alveolar bone is a clinically favorable phenotype for TDO patients.However,the limited number of bone marrow mesenchymal stem cells(BMSCs)in TDO patients restricts their application.展开更多
Three novel series of α-aminoamides derivatives were designed and synthesized based on ralfinamide,and their Nav1.7 inhibitory activities were evaluated using manual patch clamp electrophysiology. Active compounds in...Three novel series of α-aminoamides derivatives were designed and synthesized based on ralfinamide,and their Nav1.7 inhibitory activities were evaluated using manual patch clamp electrophysiology. Active compounds inhibited Nav1.7 with half maximal inhibitory concentration(IC_(50)) values ranging from2.9 μmol/L to 21.4 μmol/L. Among them, the most potent compound 19h exhibited about 12-fold potency better than ralfinamide. The investigation of their structure-activity relationship gives a strategy to improve the Nav1.7 inhibition of ralfinamide analogues. Compound 19h was efficacious in antinociception in the mouse spared nerve injury(SNI) model of neuropathic pain without causing sedation in the open field test.展开更多
基金National Natural Science Foundation of China(U22B20131)State Key Laboratory of Explosion Science and Technology(QNKT23-10)for supporting this project.
文摘Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident stimulus.Secondly, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.
基金supported by the National Nature Science Foundation of China(No.81970920,81900983)the Natural Science Foundation of Beijing Municipality,China(No.7232218)the Shanghai Science and Technology Committee Youth Sailing Program(China)(No.19YF1442500).
文摘Tricho-dento-osseous(TDO)syndrome is a rare autosomal dominant disease resulting from distal-less homeobox 3(DLX3)mutation.1,2 Accumulative bone density in alveolar bone is a clinically favorable phenotype for TDO patients.However,the limited number of bone marrow mesenchymal stem cells(BMSCs)in TDO patients restricts their application.
基金Financial supports by National Natural Science Foundation of China (Nos. 82003565 and 81973162)the Science and Technology Commission of Shanghai Municipality (No. 20S11902300,China)。
文摘Three novel series of α-aminoamides derivatives were designed and synthesized based on ralfinamide,and their Nav1.7 inhibitory activities were evaluated using manual patch clamp electrophysiology. Active compounds inhibited Nav1.7 with half maximal inhibitory concentration(IC_(50)) values ranging from2.9 μmol/L to 21.4 μmol/L. Among them, the most potent compound 19h exhibited about 12-fold potency better than ralfinamide. The investigation of their structure-activity relationship gives a strategy to improve the Nav1.7 inhibition of ralfinamide analogues. Compound 19h was efficacious in antinociception in the mouse spared nerve injury(SNI) model of neuropathic pain without causing sedation in the open field test.
