The safety factor of roof under deep high stress is a quantitative index for evaluating roof stability.Based on the failure mode of surrounding rock of stope roof,the mechanics model of goaf roof is constructed,and th...The safety factor of roof under deep high stress is a quantitative index for evaluating roof stability.Based on the failure mode of surrounding rock of stope roof,the mechanics model of goaf roof is constructed,and the internal force of roof is deduced by the theory of hingeless arch.The calculation method of roof safety factor(K)under the environment of deep mining is proposed in view of compression failure and shear failure of roof.The calculation formulas of shear safety factor(K1),compression safety factor(K2)and comprehensive safety factor(K)of roof are given.The influence of stope span and roof thickness on roof stability is considered in this paper.The results show that when the roof thickness remains constant,the roof safety factor decreases with the increasing of the stope span;when the stope span remains constant,the roof safety factor increases with the increasing of the roof thickness.The deep mining example shows that when the stope span is 30 m and the roof thickness is 10 m,the roof comprehensive safety factor is 1.12,which indicates the roof is in a stable state.展开更多
EV71-type virus is one of the main pathogens causing the occurrence of hand,foot and mouth disease(HFMD),and VP1 protein,a factor that directly determines the antigenicity of the virus,has been isolated.The tomato was...EV71-type virus is one of the main pathogens causing the occurrence of hand,foot and mouth disease(HFMD),and VP1 protein,a factor that directly determines the antigenicity of the virus,has been isolated.The tomato was selected as a bioreactor for the production of an edible EV71 vaccine designed for the VP1 capsid protein.Using molecular biology techniques,the fusion gene EV71-VP1 was cut from vector PGEX-4T-2,a vector containing the p2300-EV71 gene with CaMV35S promoter and TL regulatory elements was constructed,and the hypocotyl and cotyledons of tomato were transformed using Agrobacterium(EHA105)-mediated method,screened,elongated and rooted,and finally 20 resistant tomato plants were obtained.Five transgenic positive seedlings were obtained by digestion and PCR assay,among which three plants were detected by RT-PCR to be capable of transcriptional translation at the RNA level.The experimental results aimed to explore new material support for the preparation of transgenic plant oral vaccines against EV71 infection and provide a theoretical basis for accelerating the development of transgenic plant vaccines in the future.展开更多
基金Projects(51974135,51704094)supported by the National Natural Science Foundation of ChinaProject(2016YFC0600802)supported by the National Key Research and Development Program of ChinaProject(2020M672226)supported by the China Postdoctoral Science Foundation。
文摘The safety factor of roof under deep high stress is a quantitative index for evaluating roof stability.Based on the failure mode of surrounding rock of stope roof,the mechanics model of goaf roof is constructed,and the internal force of roof is deduced by the theory of hingeless arch.The calculation method of roof safety factor(K)under the environment of deep mining is proposed in view of compression failure and shear failure of roof.The calculation formulas of shear safety factor(K1),compression safety factor(K2)and comprehensive safety factor(K)of roof are given.The influence of stope span and roof thickness on roof stability is considered in this paper.The results show that when the roof thickness remains constant,the roof safety factor decreases with the increasing of the stope span;when the stope span remains constant,the roof safety factor increases with the increasing of the roof thickness.The deep mining example shows that when the stope span is 30 m and the roof thickness is 10 m,the roof comprehensive safety factor is 1.12,which indicates the roof is in a stable state.
基金Supported by the Natural Science Foundation of Heilongjiang Province(LH2021C032)。
文摘EV71-type virus is one of the main pathogens causing the occurrence of hand,foot and mouth disease(HFMD),and VP1 protein,a factor that directly determines the antigenicity of the virus,has been isolated.The tomato was selected as a bioreactor for the production of an edible EV71 vaccine designed for the VP1 capsid protein.Using molecular biology techniques,the fusion gene EV71-VP1 was cut from vector PGEX-4T-2,a vector containing the p2300-EV71 gene with CaMV35S promoter and TL regulatory elements was constructed,and the hypocotyl and cotyledons of tomato were transformed using Agrobacterium(EHA105)-mediated method,screened,elongated and rooted,and finally 20 resistant tomato plants were obtained.Five transgenic positive seedlings were obtained by digestion and PCR assay,among which three plants were detected by RT-PCR to be capable of transcriptional translation at the RNA level.The experimental results aimed to explore new material support for the preparation of transgenic plant oral vaccines against EV71 infection and provide a theoretical basis for accelerating the development of transgenic plant vaccines in the future.
