Phenomenon of the sediment deposition in a hydraulic jump region of open channels

The hydraulic jump is a typical sudden change for mountain river areas.The effects of local hydraulic jumps on the particle transport capacity decrease and local flow resistance increase cannot be ignored as the sediment deposition disaster can amplify the flash flood disaster.The present research investigates the influences of a hydraulic jump on the individual particle movement and sediment deposition in a laboratory flume.The overall processes of a single particle movement are captured by a high-speed camera.The distribution of sediment deposition along the hydraulic jump is obtained statistically.The results show that both the particle size and the ratio of the upstream and downstream Froude numbers affect the particle motion process.A single particle coming from upstream gradually decelerates and finally stops at the hydraulic jump section because of hydraulic jump resistance.The particle acceleration first increases and then decreases during the time-domain process,and the attenuation trends are fast with the increase of ratio of upstream and downstream of Froude numbers.The increase of the maximum acceleration with sediment flows follows a linear trend approximately,which indicates that the kinetic features of the single sand particle are determined by the coupling effects of the hydraulic jump resistance and the sand dynamic properties.With the increase of sediment rate and sand particle size,the resistance effect of hydraulic jump on sediment deposition rate along the flow direction gets strong and the sediment deposition area is mainly located upstream of the hydraulic jump region.The present study shows that the possible sediment supply upstream must be obtained for identifying the disaster risk combined with the local hydraulic jump conditions.Further researches about the detailed critical condition deduced from the relationship between the water flow and sediment deposition are required to confirm and extrapolate present results to other applications.

Prohibitin 2基因参与猪圆环病毒2型PK-15细胞感染的研究

为探究Prohibitin2(PHB2)在PCV2感染细胞过程中发挥的作用,首先通过间接免疫荧光试验检测PCV2在PK-15细胞中的增殖变化,同时建立PHB2荧光定量PCR检测体系,然后以PCV2已知的宿主细胞互作蛋白gC1qR为对照,检测PCV2感染PK-15细胞后PHB2 mRNA的动态变化,最后鉴定PHB2 siRNA转染PK-15细胞中PCV2 Cap的表达。结果表明,PHB2在正常及PCV2感染的PK-15细胞中均有效表达。随着PCV2感染PK-15细胞,gC1qR转录水平在病毒感染3 h显著降低,感染6 h时升高,随后(12~48 hpi)转录水平下降;而PHB2转录水平在PCV2感染6 h内显著升高,随后(12~48 hpi)mRNA水平有所下降;RNA干扰PHB2对PCV2在PK-15细胞中复制起到显著的抑制作用。上述研究结果表明,PCV2可显著影响PK-15细胞中PHB2转录,而且PHB2对PCV2病毒复制具有调节作用。