| 1 | Fabrication of Tβ4-Exosome-releasing artificial stem cells for myocardial infarction therapy by improving coronary collateralization显示文摘Currently,stem cell transplantations in cardiac repair are limited owing to disadvantages,such as immunological rejection and poor cell viability.Although direct injection of exosomes can have a curative effect similar to that of stem cell transplantation,high clearance hinders its application in clinical practice.Previous reports suggested that induction of coronary collateralization can be a desired method of adjunctive therapy for someone who had missed the optimal operation time to attenuate myocardial ischemia.In this study,to mimic the paracrine and biological activity of stem cells,we developed artificial stem cells that can continuously release Tβ4-exosomes(Tβ4-ASCs)by encapsulating specific exosomes within microspheres using microfluidics technology.The results show that Tβ4-ASCs can greatly promote coronary collateralization in the periphery of the myocardial infarcted area,and its therapeutic effect is superior to that of directly injecting the exosomes.In addition,to better understand how it works,we demonstrated that the Tβ4-ASC-derived exosomes can enhance the angiogenic capacity of coronary endothelial cells(CAECs)via the miR-17-5p/PHD3/Hif-1αpathway.In brief,as artificial stem cells,Tβ4-ASCs can constantly release functional exosomes and stimulate the formation of collateral circulation after myocardial infarction,providing a feasible and alternative method for clinical revascularization. | Peier Chen Xiaodong Ning Weirun Li Yuxuan Pan Ling Wang Hekai Li Xianglin Fan Jiexin Zhang Tiantian Luo Yaobin Wu Caiwen Ou Minsheng Chen | 2022 | Bioactive Materials2022，7，8： | 2 |
| 2 | Stability analysis of intermittently jointed rock slopes based on the stepped failure mode显示文摘In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering. | LI Dejian FU Junwen LI Hekai CHENG Xiao ZHAO Lianheng ZHANG Yingbin PENG Xinyan | 2024 | Journal of Mountain Science2024，21，3： | 0 |
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