The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)dire...The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)directly affect its macroscopic mechanical properties.However,there remains a notable lack of studies on the impact of explosions on loess microstructure and the quantificationof loess microstructure.This study employed micro-computed tomography(μ-CT)technology to examine loess samples extracted from the surrounding area of the explosion cavity,systematically investigating the volume,orientation,and morphological characteristics of particles and pores.The research findings indicated that the explosion caused a break for the particles with a diameter larger than 10μm,and the number of smaller particles increased.Blasting decreased the particle sphericity and orientation angle.The reduction in porosity was primarily attributed to a decrease in the volume of both macropores and mesopores,with a greater reduction in the volume of mesopores.Although the number of micropores increased,the volume change was insignificant.Furthermore,the explosion increased the pore fractal dimension and patch density,suggesting a more complex and fragmented pore structure.Moreover,the pore throat radius and channel length decreased with decreasing distance from the explosion cavity(D_(EC)),indicating that the pore's connectivity reduced.The radius of the blasting cavity was approximately 0.35 m.Additionally,the loess zone surrounding the blasting cavity was divided into failure,plastic,and elastic zones using the D_(EC)=0.2 m and 1.2 m as the boundaries.The impacts of the explosion on loess were mainly within the range of D_(EC)less than 1.20 m.The analysis of the traits,patterns,and mechanisms of explosions'impact on the loess's microstructure can provide microscopic insight into the macro-dynamic behavior,assess the impact of explosions on the surrounding loess,and identify the potential geological hazards triggered by blasting,which offers a theoretical foundation for the subsequent engineering design and security measures.展开更多
The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant stability.We present a study in which screw implants ...The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant stability.We present a study in which screw implants made from titanium,polyetheretherketone and biodegradable magnesium-gadolinium alloys were implanted into rat tibia and subjected to a push-out test four,eight and twelve weeks after implantation.Screws were 4 mm in length and with an M2 thread.The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5μm resolution.Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences.Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization.Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized.Titanium implants stimulated rapid callus formation displaying a consistent monomodal strain profile whereas the bone volume fraction in the vicinity of magnesium-gadolinium alloys exhibited a minimum close to the interface of the implant and less ordered strain transfer.Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized.This leaves the choice of biomaterial as situational depending on local tissue properties.展开更多
基金financiallysupported by the National Key&Program of China(Grant No.2022YFC3003403)the National Natural Science Foundation of China(Grant Nos.42472348 and 42220104005).
文摘The accelerated demand for engineering services has led to the extensive utilization of engineering blasting techniques.Blasting-induced changes in loess microstructure(e.g.particle breakage,pore structure change)directly affect its macroscopic mechanical properties.However,there remains a notable lack of studies on the impact of explosions on loess microstructure and the quantificationof loess microstructure.This study employed micro-computed tomography(μ-CT)technology to examine loess samples extracted from the surrounding area of the explosion cavity,systematically investigating the volume,orientation,and morphological characteristics of particles and pores.The research findings indicated that the explosion caused a break for the particles with a diameter larger than 10μm,and the number of smaller particles increased.Blasting decreased the particle sphericity and orientation angle.The reduction in porosity was primarily attributed to a decrease in the volume of both macropores and mesopores,with a greater reduction in the volume of mesopores.Although the number of micropores increased,the volume change was insignificant.Furthermore,the explosion increased the pore fractal dimension and patch density,suggesting a more complex and fragmented pore structure.Moreover,the pore throat radius and channel length decreased with decreasing distance from the explosion cavity(D_(EC)),indicating that the pore's connectivity reduced.The radius of the blasting cavity was approximately 0.35 m.Additionally,the loess zone surrounding the blasting cavity was divided into failure,plastic,and elastic zones using the D_(EC)=0.2 m and 1.2 m as the boundaries.The impacts of the explosion on loess were mainly within the range of D_(EC)less than 1.20 m.The analysis of the traits,patterns,and mechanisms of explosions'impact on the loess's microstructure can provide microscopic insight into the macro-dynamic behavior,assess the impact of explosions on the surrounding loess,and identify the potential geological hazards triggered by blasting,which offers a theoretical foundation for the subsequent engineering design and security measures.
文摘The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant stability.We present a study in which screw implants made from titanium,polyetheretherketone and biodegradable magnesium-gadolinium alloys were implanted into rat tibia and subjected to a push-out test four,eight and twelve weeks after implantation.Screws were 4 mm in length and with an M2 thread.The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5μm resolution.Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences.Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization.Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized.Titanium implants stimulated rapid callus formation displaying a consistent monomodal strain profile whereas the bone volume fraction in the vicinity of magnesium-gadolinium alloys exhibited a minimum close to the interface of the implant and less ordered strain transfer.Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized.This leaves the choice of biomaterial as situational depending on local tissue properties.
