To investigate the mechanism of asphalt modification by crumb rubber,the interactions between FCC slurry and rubber particles were evaluated at different temperatures and time.The rules of the change in mass of SARA c...To investigate the mechanism of asphalt modification by crumb rubber,the interactions between FCC slurry and rubber particles were evaluated at different temperatures and time.The rules of the change in mass of SARA composition in FCC slurry were obtained before and after its interaction with rubber particles,which showed that crumb rubber not only absorbed saturates and aromatics but also resins.Asphaltenes promoted the desulfurization or degradation of crumb rubber during the interaction between asphalt and crumb rubber.展开更多
Butt friction stir welding between pure copper and AA5754 alloy was carried out.Reinforcing SiC nanoparticles were utilized in friction stir welded(FSW)joints to decline the harmful effects of intermetallic compounds....Butt friction stir welding between pure copper and AA5754 alloy was carried out.Reinforcing SiC nanoparticles were utilized in friction stir welded(FSW)joints to decline the harmful effects of intermetallic compounds.Tensile tests,micro-hardness experiments,scanning electron microscopy and X-ray diffraction analysis were applied to studying the properties of welded joints.The joints with a travel speed of 50 mm/min and a rotation speed of 1000 r/min showed the best results.The presence of nano-sized SiC particles reduced the grain size of aluminum and copper in the stir zone(SZ)from 38.3 and 12.4μm to 12.9 and 5.1μm,respectively.The tensile strength of the joint in the presence of reinforcing SiC nano-particles was~240 MPa,which is~90%of that for the aluminum base.Furthermore,the highest microhardness of the weld zone was significantly increased from HV 160 to HV 320 upon the addition of SiC nano-particles.The results also showed that raising the heat generation in FSW joints increased the amount of Al_(4)Cu_(9) and Al_(2)Cu intermetallic compounds.展开更多
Within Baculoviridae, little is known about the molecular mechanisms of replication in betabaculoviruses, despite extensive studies in alphabaculoviruses. In this study, the promoters of nine late genes of the betabac...Within Baculoviridae, little is known about the molecular mechanisms of replication in betabaculoviruses, despite extensive studies in alphabaculoviruses. In this study, the promoters of nine late genes of the betabaculovirus Plutella xylostella granulovirus(Plxy GV) were cloned into a transient expression vector and the alphabaculovirus Autographa californica multiple nucleopolyhedrovirus(Ac MNPV) genome, and compared with homologous late gene promoters of Ac MNPV in Sf9 cells. In transient expression assays, all Plxy GV late promoters were activated in cells transfected with the individual reporter plasmids together with an Ac MNPV bacmid. In infected cells, reporter gene expression levels with the promoters of Plxy GV e18 and Ac MNPV vp39 and gp41 were significantly higher than those of the corresponding Ac MNPV or Plxy GV promoters,which had fewer late promoter motifs. Observed expression levels were lower for the Plxy GV p6.9,pk1, gran, p10 a, and p10 b promoters than for the corresponding Ac MNPV promoters, despite equal numbers of late promoter motifs, indicating that species-specific elements contained in some late promoters were favored by the native viral RNA polymerases for optimal transcription. The 8-nt sequence TAAATAAG encompassing the ATAAG motif was conserved in the Ac MNPV polh, p10,and pk1 promoters. The 5-nt sequence CAATT located 4 or 5 nt upstream of the T/ATAAG motif was conserved in the promoters of Plxy GV gran, p10 c, and pk1. The results of this study demonstrated that Plxy GV late gene promoters could be effectively activated by the RNA polymerase from Ac MNPV, implying that late gene expression systems are regulated by similar mechanisms in alphabaculoviruses and betabaculoviruses.展开更多
文摘To investigate the mechanism of asphalt modification by crumb rubber,the interactions between FCC slurry and rubber particles were evaluated at different temperatures and time.The rules of the change in mass of SARA composition in FCC slurry were obtained before and after its interaction with rubber particles,which showed that crumb rubber not only absorbed saturates and aromatics but also resins.Asphaltenes promoted the desulfurization or degradation of crumb rubber during the interaction between asphalt and crumb rubber.
文摘Butt friction stir welding between pure copper and AA5754 alloy was carried out.Reinforcing SiC nanoparticles were utilized in friction stir welded(FSW)joints to decline the harmful effects of intermetallic compounds.Tensile tests,micro-hardness experiments,scanning electron microscopy and X-ray diffraction analysis were applied to studying the properties of welded joints.The joints with a travel speed of 50 mm/min and a rotation speed of 1000 r/min showed the best results.The presence of nano-sized SiC particles reduced the grain size of aluminum and copper in the stir zone(SZ)from 38.3 and 12.4μm to 12.9 and 5.1μm,respectively.The tensile strength of the joint in the presence of reinforcing SiC nano-particles was~240 MPa,which is~90%of that for the aluminum base.Furthermore,the highest microhardness of the weld zone was significantly increased from HV 160 to HV 320 upon the addition of SiC nano-particles.The results also showed that raising the heat generation in FSW joints increased the amount of Al_(4)Cu_(9) and Al_(2)Cu intermetallic compounds.
基金supported by the fund of Hubei Key Laboratory of Genetic Regulation and Integrative Biology
文摘Within Baculoviridae, little is known about the molecular mechanisms of replication in betabaculoviruses, despite extensive studies in alphabaculoviruses. In this study, the promoters of nine late genes of the betabaculovirus Plutella xylostella granulovirus(Plxy GV) were cloned into a transient expression vector and the alphabaculovirus Autographa californica multiple nucleopolyhedrovirus(Ac MNPV) genome, and compared with homologous late gene promoters of Ac MNPV in Sf9 cells. In transient expression assays, all Plxy GV late promoters were activated in cells transfected with the individual reporter plasmids together with an Ac MNPV bacmid. In infected cells, reporter gene expression levels with the promoters of Plxy GV e18 and Ac MNPV vp39 and gp41 were significantly higher than those of the corresponding Ac MNPV or Plxy GV promoters,which had fewer late promoter motifs. Observed expression levels were lower for the Plxy GV p6.9,pk1, gran, p10 a, and p10 b promoters than for the corresponding Ac MNPV promoters, despite equal numbers of late promoter motifs, indicating that species-specific elements contained in some late promoters were favored by the native viral RNA polymerases for optimal transcription. The 8-nt sequence TAAATAAG encompassing the ATAAG motif was conserved in the Ac MNPV polh, p10,and pk1 promoters. The 5-nt sequence CAATT located 4 or 5 nt upstream of the T/ATAAG motif was conserved in the promoters of Plxy GV gran, p10 c, and pk1. The results of this study demonstrated that Plxy GV late gene promoters could be effectively activated by the RNA polymerase from Ac MNPV, implying that late gene expression systems are regulated by similar mechanisms in alphabaculoviruses and betabaculoviruses.
