Fragment velocity distribution is an important parameter affecting the terminal effects of warheads.The rarefaction wave,end cap,and its confinement state can significantly affect the fragmentation of the cylindrical ...Fragment velocity distribution is an important parameter affecting the terminal effects of warheads.The rarefaction wave,end cap,and its confinement state can significantly affect the fragmentation of the cylindrical charge casing.Most of the existing studies have performed experiments and simulations considering the rarefaction wave and unfixed end caps;research on fixed end caps and sufficient theoretical explanations are limited.In this work,the effects of rarefaction waves,end caps,and their fixed states,on the fragment velocity distribution,were studied via experimentation and simulation,and reasonable theoretical explanations were provided.The results show that the rarefaction wave and end caps affect the fragment velocity by changing the pressure states of the detonation products.At the initiation end,the fragment velocities of casings with unfixed initiation ends are 33.3%(300 m/s)greater than that of casings without end caps,because of the weakening of the attenuation effect of the rarefaction wave.The fragment velocities of the casings with fixed initiation ends are 8.3%(100 m/s)greater than that of casings with unfixed initiation ends.At the non-initiation end,the fragment velocities are 24.8%(297 m/s)greater than that of a casing without end caps,and the reflecting shock wave generated by the fixed non-initiation end increases the fragment velocity by 7.3%(113 m/s),compared to the theoretical velocity.This work provides a basis for the structural design and analysis of the terminal effects of warheads.展开更多
Lignin is a significant secondary metabolite produced through the phenylpropanoid pathway.As a vital component of the plant cell wall,lignin affects various fruit characteristics,including size,seed quantity,and firmn...Lignin is a significant secondary metabolite produced through the phenylpropanoid pathway.As a vital component of the plant cell wall,lignin affects various fruit characteristics,including size,seed quantity,and firmness.In this study,we conducted comprehensive identification and phylogenetic analysis of 265 Caffeic acid O-methyltransferase(COMT)genes across ten different plant species,including Vaccinium corymbosum and four other Vaccinium species.The results reveal that VcCOMT38 is a promising structural gene for the biosynthesis of lignin in blueberry.An in vitro enzymatic assay of VcCOMT38 demonstrated that it is a special enzyme in the lignin biosynthesis pathway and prefers to use caffeic acid as a substrate over 5-hydroxyferulic acid.Transient overexpression and silencing of VcCOMT38 in Vaccinium corymbosum‘Northland’fruits demonstrated that VcCOMT38 participates in lignin biosynthesis and contributes to both an increased number of immature seeds and enhanced fruit firmness.The heterologous overexpression of VcCOMT38 in Nicotiana benthamiana revealed that this gene could increase the lignin content and the syringyl/guaiacyl(S/G)ratio,which determines the maximum monomer yield during lignin depolymerization.These results highlight VcCOMT38 as a crucial gene in lignin biosynthesis and its potential for improving lignin production in industry through genetically modified woody plants.展开更多
基金the support of the Youth Scientific Research Projects of the Basic Research Program of Shanxi Province(Grant Nos.202303021222111,202303021222113)the China Postdoctoral Science Foundation(Grant No.2025M770001).
文摘Fragment velocity distribution is an important parameter affecting the terminal effects of warheads.The rarefaction wave,end cap,and its confinement state can significantly affect the fragmentation of the cylindrical charge casing.Most of the existing studies have performed experiments and simulations considering the rarefaction wave and unfixed end caps;research on fixed end caps and sufficient theoretical explanations are limited.In this work,the effects of rarefaction waves,end caps,and their fixed states,on the fragment velocity distribution,were studied via experimentation and simulation,and reasonable theoretical explanations were provided.The results show that the rarefaction wave and end caps affect the fragment velocity by changing the pressure states of the detonation products.At the initiation end,the fragment velocities of casings with unfixed initiation ends are 33.3%(300 m/s)greater than that of casings without end caps,because of the weakening of the attenuation effect of the rarefaction wave.The fragment velocities of the casings with fixed initiation ends are 8.3%(100 m/s)greater than that of casings with unfixed initiation ends.At the non-initiation end,the fragment velocities are 24.8%(297 m/s)greater than that of a casing without end caps,and the reflecting shock wave generated by the fixed non-initiation end increases the fragment velocity by 7.3%(113 m/s),compared to the theoretical velocity.This work provides a basis for the structural design and analysis of the terminal effects of warheads.
文摘Lignin is a significant secondary metabolite produced through the phenylpropanoid pathway.As a vital component of the plant cell wall,lignin affects various fruit characteristics,including size,seed quantity,and firmness.In this study,we conducted comprehensive identification and phylogenetic analysis of 265 Caffeic acid O-methyltransferase(COMT)genes across ten different plant species,including Vaccinium corymbosum and four other Vaccinium species.The results reveal that VcCOMT38 is a promising structural gene for the biosynthesis of lignin in blueberry.An in vitro enzymatic assay of VcCOMT38 demonstrated that it is a special enzyme in the lignin biosynthesis pathway and prefers to use caffeic acid as a substrate over 5-hydroxyferulic acid.Transient overexpression and silencing of VcCOMT38 in Vaccinium corymbosum‘Northland’fruits demonstrated that VcCOMT38 participates in lignin biosynthesis and contributes to both an increased number of immature seeds and enhanced fruit firmness.The heterologous overexpression of VcCOMT38 in Nicotiana benthamiana revealed that this gene could increase the lignin content and the syringyl/guaiacyl(S/G)ratio,which determines the maximum monomer yield during lignin depolymerization.These results highlight VcCOMT38 as a crucial gene in lignin biosynthesis and its potential for improving lignin production in industry through genetically modified woody plants.
