A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the t...A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.展开更多
目的 探讨复方蛇龙胶囊抑制Bax/Caspase-3信号通路减轻膜性肾病大鼠肾组织细胞凋亡的影响。方法 抽取10只6周龄SPF级雄性SD大鼠作为正常组,其余40只采用注射阳离子化牛血清白蛋白(Alb)构建膜性肾病大鼠模型,采用随机数字表法将其分为模...目的 探讨复方蛇龙胶囊抑制Bax/Caspase-3信号通路减轻膜性肾病大鼠肾组织细胞凋亡的影响。方法 抽取10只6周龄SPF级雄性SD大鼠作为正常组,其余40只采用注射阳离子化牛血清白蛋白(Alb)构建膜性肾病大鼠模型,采用随机数字表法将其分为模型组,雷公藤多苷片组,复方蛇龙胶囊低、高剂量组,每组10只。除正常组和模型组灌服等量生理盐水外,其余各组灌胃给予相应药物,连续4周。HE染色、Masson染色、透射电镜及扫描电镜观察各组肾组织病理学变化;比较各组大鼠尿微量白蛋白(mAlb)和血肌酐(SCr)、甘油三酯(TG)、总胆固醇(TC)、Alb、总蛋白(TP)含量;比较各组大鼠肾组织细胞凋亡率;比较各组大鼠肾组织Nephrin、Podocin、Bcl-2、Bax和Caspase-3 m RNA表达水平。结果 与正常组比较,模型组大鼠尿m Alb含量升高(P<0.05);血清Alb、TP含量降低,TC、TG和SCr含量升高(P<0.05)。与模型组比较,复方蛇龙胶囊低、高剂量组大鼠尿m Alb含量降低(P<0.05);血清Alb、TP含量升高,TC、TG和SCr含量降低(P<0.05)。与复方蛇龙胶囊低剂量组比较,复方蛇龙胶囊高剂量组尿m Alb降低(P<0.05);血清Alb、TP含量升高,SCr含量降低(P<0.05)。正常组大鼠HE染色可见肾小球结构完整;Masson染色未见组织纤维化。模型组大鼠HE染色可见肾小球体积增大,肾小管可见空泡变性,并伴有蛋白管型;Masson染色可见组织纤维化,蓝色胶原纤维组织出现。与模型组比较,复方蛇龙胶囊低、高剂量组大鼠肾小球体积增大、肾小管空泡变性及组织纤维化有所减轻。正常组基底膜结构完整,足细胞结构正常;模型组肾小球大面积水肿,基底膜增厚,足突融合变宽,足细胞结构严重损伤,细胞骨架蛋白裸露;与模型组比较,复方蛇龙胶囊低、高剂量组大鼠基底膜增厚程度减轻,足细胞形态结构趋于正常。与正常组比较,模型组大鼠肾组织细胞凋亡率升高(P<0.05);与模型组比较,复方蛇龙胶囊低、高剂量组大鼠肾组织细胞凋亡率降低(P<0.05);与复方蛇龙胶囊低剂量组比较,复方蛇龙胶囊高剂量组大鼠肾组织细胞凋亡率降低(P<0.05)。与正常组比较,模型组大鼠Nephrin、Podocin、Bcl-2 m RNA表达水平降低,Caspase-3、Bax m RNA表达水平升高,Bcl-2/Bax比值降低(P<0.05)。与模型组比较,复方蛇龙胶囊低、高剂量组大鼠Nephrin、Podocin、Bcl-2 m RNA表达水平升高,Caspase-3、Bax m RNA表达水平降低,Bcl-2/Bax比值升高(P<0.05)。与复方蛇龙胶囊低剂量组比较,复方蛇龙胶囊高剂量组Nephrin、Podocin m RNA表达水平升高,Bcl-2/Bax比值升高(P<0.05)。结论 复方蛇龙胶囊能有效改善膜性肾病大鼠蛋白尿,显著减轻肾脏病理损伤,延缓膜性肾病进展,其机制可能与抑制足细胞凋亡有关。展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U22A20602,U2040221).
文摘A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.
文摘目的 探讨复方蛇龙胶囊抑制Bax/Caspase-3信号通路减轻膜性肾病大鼠肾组织细胞凋亡的影响。方法 抽取10只6周龄SPF级雄性SD大鼠作为正常组,其余40只采用注射阳离子化牛血清白蛋白(Alb)构建膜性肾病大鼠模型,采用随机数字表法将其分为模型组,雷公藤多苷片组,复方蛇龙胶囊低、高剂量组,每组10只。除正常组和模型组灌服等量生理盐水外,其余各组灌胃给予相应药物,连续4周。HE染色、Masson染色、透射电镜及扫描电镜观察各组肾组织病理学变化;比较各组大鼠尿微量白蛋白(mAlb)和血肌酐(SCr)、甘油三酯(TG)、总胆固醇(TC)、Alb、总蛋白(TP)含量;比较各组大鼠肾组织细胞凋亡率;比较各组大鼠肾组织Nephrin、Podocin、Bcl-2、Bax和Caspase-3 m RNA表达水平。结果 与正常组比较,模型组大鼠尿m Alb含量升高(P<0.05);血清Alb、TP含量降低,TC、TG和SCr含量升高(P<0.05)。与模型组比较,复方蛇龙胶囊低、高剂量组大鼠尿m Alb含量降低(P<0.05);血清Alb、TP含量升高,TC、TG和SCr含量降低(P<0.05)。与复方蛇龙胶囊低剂量组比较,复方蛇龙胶囊高剂量组尿m Alb降低(P<0.05);血清Alb、TP含量升高,SCr含量降低(P<0.05)。正常组大鼠HE染色可见肾小球结构完整;Masson染色未见组织纤维化。模型组大鼠HE染色可见肾小球体积增大,肾小管可见空泡变性,并伴有蛋白管型;Masson染色可见组织纤维化,蓝色胶原纤维组织出现。与模型组比较,复方蛇龙胶囊低、高剂量组大鼠肾小球体积增大、肾小管空泡变性及组织纤维化有所减轻。正常组基底膜结构完整,足细胞结构正常;模型组肾小球大面积水肿,基底膜增厚,足突融合变宽,足细胞结构严重损伤,细胞骨架蛋白裸露;与模型组比较,复方蛇龙胶囊低、高剂量组大鼠基底膜增厚程度减轻,足细胞形态结构趋于正常。与正常组比较,模型组大鼠肾组织细胞凋亡率升高(P<0.05);与模型组比较,复方蛇龙胶囊低、高剂量组大鼠肾组织细胞凋亡率降低(P<0.05);与复方蛇龙胶囊低剂量组比较,复方蛇龙胶囊高剂量组大鼠肾组织细胞凋亡率降低(P<0.05)。与正常组比较,模型组大鼠Nephrin、Podocin、Bcl-2 m RNA表达水平降低,Caspase-3、Bax m RNA表达水平升高,Bcl-2/Bax比值降低(P<0.05)。与模型组比较,复方蛇龙胶囊低、高剂量组大鼠Nephrin、Podocin、Bcl-2 m RNA表达水平升高,Caspase-3、Bax m RNA表达水平降低,Bcl-2/Bax比值升高(P<0.05)。与复方蛇龙胶囊低剂量组比较,复方蛇龙胶囊高剂量组Nephrin、Podocin m RNA表达水平升高,Bcl-2/Bax比值升高(P<0.05)。结论 复方蛇龙胶囊能有效改善膜性肾病大鼠蛋白尿,显著减轻肾脏病理损伤,延缓膜性肾病进展,其机制可能与抑制足细胞凋亡有关。
