目的采用Box-Behnken效应面优化姜黄素长循环纳米结构脂质载体(mPEG2000-Cur-NLC)处方,并考察其理化性质。方法采用薄膜-超声法制备mPEG2000-Cur-NLC,以粒径、包封率和载药量为评价指标,以混合脂质的用量、乳化剂的用量和脂药质量比为...目的采用Box-Behnken效应面优化姜黄素长循环纳米结构脂质载体(mPEG2000-Cur-NLC)处方,并考察其理化性质。方法采用薄膜-超声法制备mPEG2000-Cur-NLC,以粒径、包封率和载药量为评价指标,以混合脂质的用量、乳化剂的用量和脂药质量比为考察对象,采用Box-Behnken效应面法筛选其最佳处方,并考察其粒径、包封率、zeta电位及体外释放。结果最优处方为混合脂质用量为质量分数2.5%、乳化剂的用量质量分数3.5%和脂药质量比40∶1,按最优处方制备的m PEG2000-Cur-NLC粒径为(135.33±2.52)nm、包封率为(96.70±0.146)%、载药量为(2.41±0.587)%,体外释放72h药物累积释放量为58.37%,呈缓释释放,Weibull方程拟合结果最好。结论 m PEG2000-Cur-NLC采用Box-Behnken效应面法优化是可行的,体外缓释效果良好。展开更多
Rock pillar is the key supporting component in underground engineering.During an earthquake,the key rock pillar must bear both the seismic load and the load transferred from other damaged pillars.This paper attempts t...Rock pillar is the key supporting component in underground engineering.During an earthquake,the key rock pillar must bear both the seismic load and the load transferred from other damaged pillars.This paper attempts to reveal the influence of the mainshock on damage evolution and failure characteristic of the key rock pillar during aftershocks by cyclic loading test of marble.Four levels of pre-damage stress(i.e.,10,30,50 and 70 MPa)in the first cycle were used to simulate the mainshock damage,and then cyclic stress with the same amplitude(namely 10 MPa)was conducted in the subsequent cycles to simulate the aftershock until rock failure.The results indicate that the presence of pre-damage has an obvious weakening effect on the bearing capacity and deformation resistance of rock materials during the aftershock process.Besides,the increase of pre-damage significantly changes the final failure pattern of the key rock pillar,and leads to an increase in the proportion of small-scale rock fragments.This study may contribute to understanding the seismic capacity of the unreinforced rock pillar during mainshock-aftershock seismic sequences and to optimizing the design of the key rock pillar in underground engineering.展开更多
Aiming to investigate the fatigue damage mechanism and bearing characteristics of multi-pillar system under cyclic loading,a series of axial cyclic loading tests with different cyclic amplitudes were carried out on tr...Aiming to investigate the fatigue damage mechanism and bearing characteristics of multi-pillar system under cyclic loading,a series of axial cyclic loading tests with different cyclic amplitudes were carried out on triple-pillar marble specimens.The acoustic emission(AE)and digital image correlation(DIC)were jointly applied to monitoring and recording damage evolution and failure behavior of each pillar,which reproduced the cataclysmic instability process of underground pillar groups.Experimental results indicated that the cyclic amplitude exceeding the threshold of damage initiation weakened the resistance to deformation,resulting in obvious release of dissipated energy and the reduction of bearing capacity.Conversely,after low-amplitude cyclic loading,both the pre-peak bearing capacity and the post-peak ductility of the pillar system increased due to the compaction of initial defects,indicating that the peak bearing capacity was closely related to the extent of pre-peak fatigue damage.The axial strain of each pillar was measured by DIC virtual extensometer to present the damage extent during cyclic loading phase.Meanwhile,fracture evolution of typical load drop points was also characterized by transverse strain fields(εxx),and observations showed that the damage extent of key pillar undergoing high-amplitude cyclic loads was more serious and violent,accompanied by the ejection of rock debris and loud noises.展开更多
文摘目的采用Box-Behnken效应面优化姜黄素长循环纳米结构脂质载体(mPEG2000-Cur-NLC)处方,并考察其理化性质。方法采用薄膜-超声法制备mPEG2000-Cur-NLC,以粒径、包封率和载药量为评价指标,以混合脂质的用量、乳化剂的用量和脂药质量比为考察对象,采用Box-Behnken效应面法筛选其最佳处方,并考察其粒径、包封率、zeta电位及体外释放。结果最优处方为混合脂质用量为质量分数2.5%、乳化剂的用量质量分数3.5%和脂药质量比40∶1,按最优处方制备的m PEG2000-Cur-NLC粒径为(135.33±2.52)nm、包封率为(96.70±0.146)%、载药量为(2.41±0.587)%,体外释放72h药物累积释放量为58.37%,呈缓释释放,Weibull方程拟合结果最好。结论 m PEG2000-Cur-NLC采用Box-Behnken效应面法优化是可行的,体外缓释效果良好。
基金Project(2022MD713784) supported by China Postdoctoral ScienceProject (1960321032) supported by the Research Start-up Fund Project for High-level Talents Introduction,ChinaProject (1609722058) supported by Xi’ an University of Architecture and Technology,China。
文摘Rock pillar is the key supporting component in underground engineering.During an earthquake,the key rock pillar must bear both the seismic load and the load transferred from other damaged pillars.This paper attempts to reveal the influence of the mainshock on damage evolution and failure characteristic of the key rock pillar during aftershocks by cyclic loading test of marble.Four levels of pre-damage stress(i.e.,10,30,50 and 70 MPa)in the first cycle were used to simulate the mainshock damage,and then cyclic stress with the same amplitude(namely 10 MPa)was conducted in the subsequent cycles to simulate the aftershock until rock failure.The results indicate that the presence of pre-damage has an obvious weakening effect on the bearing capacity and deformation resistance of rock materials during the aftershock process.Besides,the increase of pre-damage significantly changes the final failure pattern of the key rock pillar,and leads to an increase in the proportion of small-scale rock fragments.This study may contribute to understanding the seismic capacity of the unreinforced rock pillar during mainshock-aftershock seismic sequences and to optimizing the design of the key rock pillar in underground engineering.
基金Project(2015CB060200)supported by the National Basic Research Program of ChinaProject(41772313)supported by the National Natural Science Foundation of ChinaProject(2017zzts185)supported by the Fundamental Research Funds for the Central Universities,China
文摘Aiming to investigate the fatigue damage mechanism and bearing characteristics of multi-pillar system under cyclic loading,a series of axial cyclic loading tests with different cyclic amplitudes were carried out on triple-pillar marble specimens.The acoustic emission(AE)and digital image correlation(DIC)were jointly applied to monitoring and recording damage evolution and failure behavior of each pillar,which reproduced the cataclysmic instability process of underground pillar groups.Experimental results indicated that the cyclic amplitude exceeding the threshold of damage initiation weakened the resistance to deformation,resulting in obvious release of dissipated energy and the reduction of bearing capacity.Conversely,after low-amplitude cyclic loading,both the pre-peak bearing capacity and the post-peak ductility of the pillar system increased due to the compaction of initial defects,indicating that the peak bearing capacity was closely related to the extent of pre-peak fatigue damage.The axial strain of each pillar was measured by DIC virtual extensometer to present the damage extent during cyclic loading phase.Meanwhile,fracture evolution of typical load drop points was also characterized by transverse strain fields(εxx),and observations showed that the damage extent of key pillar undergoing high-amplitude cyclic loads was more serious and violent,accompanied by the ejection of rock debris and loud noises.
