The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this...The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, l.SCr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25 urn thick and consisted of the intermetallic compound FeCr with an average grain size of 25±10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.展开更多
In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ran...In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ranged from 40~60 nm and 100~200 nm according to different requirements. SEM and TEM showed that the particle size considerably decreases with increasing emulsification concentration and decreasing PLA concentration and ratio of oil to water. The highest drug loading ratio and drug encapsulation efficiency of NPs were 5.63% and 33.45%. The results demonstrated that decrease of initial BCNU content resulted in a noticeably increased encapsulation yield. A thorough study in vitro showed that the drug could be steadily released from NPs for one week. In addition,drug-loaded NPs had higher antitumor activity,compared with free BCNU,and sustained drug release characteristics as well.展开更多
基金supported by the National Natural Science Foundation of Chinathe Chinese Academy of Sciences
文摘The surface mechanical attrition treatment (SMAT) technique was developed to synthesize a nanocrystalline (NC) layer on the surface of metallic materials for upgrading their overall properties and performance. In this paper, by means of SMAT to a pure zirconium plate at the room temperature, repetitive multidirectional peening of steel shots (composition (wt%): 1C, l.SCr, base Fe) severely deformed the surface layer. A NC surface layer consisting of the intermetallic compound FeCr was fabricated on the surface of the zirconium. The microstructure characterization of the surface layer was performed by using X-ray diffraction analysis, optical microscopy, scanning and transmission electron microscopy observations. The NC surface layer was about 25 urn thick and consisted of the intermetallic compound FeCr with an average grain size of 25±10 nm. The deformation-induced fast diffusion of Fe and Cr from the steel shots into Zr occurred during SMAT, leading to the formation of intermetallic compound. In addition, the NC surface layer exhibited an ultrahigh nanohardness of 10.2 GPa.
文摘In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ranged from 40~60 nm and 100~200 nm according to different requirements. SEM and TEM showed that the particle size considerably decreases with increasing emulsification concentration and decreasing PLA concentration and ratio of oil to water. The highest drug loading ratio and drug encapsulation efficiency of NPs were 5.63% and 33.45%. The results demonstrated that decrease of initial BCNU content resulted in a noticeably increased encapsulation yield. A thorough study in vitro showed that the drug could be steadily released from NPs for one week. In addition,drug-loaded NPs had higher antitumor activity,compared with free BCNU,and sustained drug release characteristics as well.
