Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause.However,barrier structures constructed along the path of a rock avalanche can partia...Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause.However,barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic events.We selected a rock avalanche in Nayong County,Guizhou Province,China as a case to study the effect of the location and height of a retaining wall on the dynamic characteristics of rock avalanche by using both actual terrain-based laboratory-model tests and coupled PFC3D-FLAC3D numerical simulations.Our findings demonstrate that a retaining wall can largely block a rock avalanche and its protective efficacy is significantly influenced by the integrity of the retaining wall.Coupled numerical simulation can serve as a powerful tool for analyzing the interaction between a rock avalanche and a retaining wall,facilitating precise observations of its deformation and destruction.The impact-curve characteristics of the retaining wall depend upon whether or not the rock avalanche-induced destruction is taken into account.The location of the retaining wall exerts a greater influence on the outcome compared to the height and materials of the retaining wall,while implementing a stepped retaining-wall pattern in accordance with the terrain demonstrates optimal efficacy in controlling rock avalanche.展开更多
目的以黄精生品及酒制品中水溶性多糖为研究对象,对两者抗氧化活性进行研究。方法通过水提、醇沉、除蛋白透析得黄精生品水溶性多糖和酒制品水溶性多糖;采用还原力实验、1-二苯基-2-三硝基苯肼(DPPH)、羟基自由基(·OH)及超氧阴离...目的以黄精生品及酒制品中水溶性多糖为研究对象,对两者抗氧化活性进行研究。方法通过水提、醇沉、除蛋白透析得黄精生品水溶性多糖和酒制品水溶性多糖;采用还原力实验、1-二苯基-2-三硝基苯肼(DPPH)、羟基自由基(·OH)及超氧阴离子自由基(·O-2)清除法对其抗氧化活性进行评价;建立Cu^(2+)/H_(2)O_(2)诱导的BSA蛋白损伤模型,评价两者对氧化损伤蛋白的保护作用;建立体外H_(2)O_(2)诱导的RAW264.7细胞氧化损伤模型,对细胞活力、细胞中T-SOD、CAT、GSH酶活力及MDA、ROS含量进行测定,评价两者对氧化损伤细胞的保护作用。结果通过水提醇沉得黄精生品水溶性多糖(Polysaccharides from crude Polygonatum sibiricum,PSPC)和酒制品水溶性多糖(Polysaccharides from wine-processed Polygonatum sibiricum,PSPW)。抗氧化研究结果表明PSPC和PSPW均有一定的还原力、清除DPPH自由基、清除超氧阴离子自由基和清除羟基自由基能力;PSPC和PSPW对Cu^(2+)/H_(2)O_(2)诱导的BSA蛋白损伤有一定的保护作用;PSPC和PSPW对H_(2)O_(2)诱导的RAW264.7细胞活力降低有保护作用,对氧化损伤细胞内T-SOD和GSH酶活力降低有恢复作用,对MDA和ROS升高有抑制作用并呈一定的浓度依赖性,PSPW抗氧化活性均显著强于PSPC(P<0.05)。结论黄精酒制后其水溶性多糖PSPW抗氧化活性增强,PSPW可作为一种潜在天然抗氧化剂,为后续黄精酒制机制深入研究以及黄精多糖保健品开发提供研究基础。展开更多
目的对酒制黄精水溶性多糖(Polysaccharides from wine-processed Polygonatum sibiricum.,PSPW)进行分步醇沉,对各醇沉组分理化性质及免疫活性进行研究。方法采用分步醇沉法对PSPW进行分离、纯化;采用气相色谱(GC)、高效凝胶渗透色谱(H...目的对酒制黄精水溶性多糖(Polysaccharides from wine-processed Polygonatum sibiricum.,PSPW)进行分步醇沉,对各醇沉组分理化性质及免疫活性进行研究。方法采用分步醇沉法对PSPW进行分离、纯化;采用气相色谱(GC)、高效凝胶渗透色谱(HPGPC)及傅里叶变换红外光谱(FT-IR)等方法对各醇沉组分的理化性质进行研究;采用MTT法、中性红吞噬实验及Griess法评价各醇沉组分对RAW 264.7细胞免疫活性的影响。结果随分步醇沉中所用乙醇浓度增加,依次获得0~30%、30%~50%、50%~70%及70%~80%多糖组分,分别命名为PSPW-1、PSPW-2、PSPW-3及PSPW-4;理化性质结果表明4个醇沉组分(分子量分别为2.26×10^(4)、2.24×10^(4)、1.15×10^(4)及6.58×10^(3)u)均为糖蛋白复合物;各醇沉组分单糖组成种类和比例存在显著差异,均含高比例的半乳糖;免疫活性研究表明各组分均可促进RAW264.7细胞活力、吞噬中性红能力、分泌NO能力及分泌酸性磷酸酶活力,其中组分PSPW-3免疫活性最强。结论分步醇沉法所得PSPW各醇沉组分理化性质和免疫活性存在较大差异,推测PSPW-3为酒制黄精多糖发挥免疫调节作用的最佳活性组分,本研究为酒制黄精多糖最佳免疫调节活性组分的构效关系及黄精多糖功能性食品开发提供依据。展开更多
泥石流灾害是较常见且频发的地质灾害之一,常造成大量人员伤亡和财产损失。以空心寨沟泥石流为例,采用地面调查、室内试验、现场试验、定性分析及定量评价相结合的方法,分析了泥石流的基本特征,确定了相关的动力学参数,揭示了泥石流的...泥石流灾害是较常见且频发的地质灾害之一,常造成大量人员伤亡和财产损失。以空心寨沟泥石流为例,采用地面调查、室内试验、现场试验、定性分析及定量评价相结合的方法,分析了泥石流的基本特征,确定了相关的动力学参数,揭示了泥石流的形成规律及灾变机制。研究结果表明,空心寨沟泥石流为中频—暴雨—崩塌—滑坡—沟谷型黏性泥石流,目前处于壮年期,计算暴雨频率在P=5%条件下空心寨沟泥石流的平均流速为6.91 m/s,峰值流量达142.58 m 3/s,其中一次泥石流冲出流体总量为2.9104×104 m 3,冲出固体总量为1.5875×104 m 3。研究结果为制定空心寨沟泥石流灾害防治措施提供了重要依据。展开更多
基金Hunan Provincial key Laboratory of key Technology on Hydropower Development Open Research Fund (PKLHD202203)
文摘Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause.However,barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic events.We selected a rock avalanche in Nayong County,Guizhou Province,China as a case to study the effect of the location and height of a retaining wall on the dynamic characteristics of rock avalanche by using both actual terrain-based laboratory-model tests and coupled PFC3D-FLAC3D numerical simulations.Our findings demonstrate that a retaining wall can largely block a rock avalanche and its protective efficacy is significantly influenced by the integrity of the retaining wall.Coupled numerical simulation can serve as a powerful tool for analyzing the interaction between a rock avalanche and a retaining wall,facilitating precise observations of its deformation and destruction.The impact-curve characteristics of the retaining wall depend upon whether or not the rock avalanche-induced destruction is taken into account.The location of the retaining wall exerts a greater influence on the outcome compared to the height and materials of the retaining wall,while implementing a stepped retaining-wall pattern in accordance with the terrain demonstrates optimal efficacy in controlling rock avalanche.
文摘目的以黄精生品及酒制品中水溶性多糖为研究对象,对两者抗氧化活性进行研究。方法通过水提、醇沉、除蛋白透析得黄精生品水溶性多糖和酒制品水溶性多糖;采用还原力实验、1-二苯基-2-三硝基苯肼(DPPH)、羟基自由基(·OH)及超氧阴离子自由基(·O-2)清除法对其抗氧化活性进行评价;建立Cu^(2+)/H_(2)O_(2)诱导的BSA蛋白损伤模型,评价两者对氧化损伤蛋白的保护作用;建立体外H_(2)O_(2)诱导的RAW264.7细胞氧化损伤模型,对细胞活力、细胞中T-SOD、CAT、GSH酶活力及MDA、ROS含量进行测定,评价两者对氧化损伤细胞的保护作用。结果通过水提醇沉得黄精生品水溶性多糖(Polysaccharides from crude Polygonatum sibiricum,PSPC)和酒制品水溶性多糖(Polysaccharides from wine-processed Polygonatum sibiricum,PSPW)。抗氧化研究结果表明PSPC和PSPW均有一定的还原力、清除DPPH自由基、清除超氧阴离子自由基和清除羟基自由基能力;PSPC和PSPW对Cu^(2+)/H_(2)O_(2)诱导的BSA蛋白损伤有一定的保护作用;PSPC和PSPW对H_(2)O_(2)诱导的RAW264.7细胞活力降低有保护作用,对氧化损伤细胞内T-SOD和GSH酶活力降低有恢复作用,对MDA和ROS升高有抑制作用并呈一定的浓度依赖性,PSPW抗氧化活性均显著强于PSPC(P<0.05)。结论黄精酒制后其水溶性多糖PSPW抗氧化活性增强,PSPW可作为一种潜在天然抗氧化剂,为后续黄精酒制机制深入研究以及黄精多糖保健品开发提供研究基础。
文摘泥石流灾害是较常见且频发的地质灾害之一,常造成大量人员伤亡和财产损失。以空心寨沟泥石流为例,采用地面调查、室内试验、现场试验、定性分析及定量评价相结合的方法,分析了泥石流的基本特征,确定了相关的动力学参数,揭示了泥石流的形成规律及灾变机制。研究结果表明,空心寨沟泥石流为中频—暴雨—崩塌—滑坡—沟谷型黏性泥石流,目前处于壮年期,计算暴雨频率在P=5%条件下空心寨沟泥石流的平均流速为6.91 m/s,峰值流量达142.58 m 3/s,其中一次泥石流冲出流体总量为2.9104×104 m 3,冲出固体总量为1.5875×104 m 3。研究结果为制定空心寨沟泥石流灾害防治措施提供了重要依据。
