SPH study of the evolution of water–water interfaces in dam break flows

The mixing process of upstream and downstream waters in the dam break flow could generate significant ecological impact on the downstream reaches and influence the environmental damages caused by the dam break flood. This is not easily investigated with the analytical and numerical models based on the grid method due to the large deformation of free surface and the water-water interface. In this paper, a weakly compressible Smoothed Particle Hydrodynamics (WCSPH) solver is used to study the advection and mixing process of the water bodies in two-dimensional dam-break flows over a wet bed. The numerical results of the mixing dynamics immediately after the release of the dam water are found to agree satisfactorily with the published experimental and numerical results. Then further investigations are carried out to study the interface development at the later stage of dambreak flows in a long channel. The analyses concentrate on the evolution of the interface at different ratios between the upstream and downstream water depths. The potential capabilities of the mesh-free SPH modelling approach for predicting the detailed development of the water-water interfaces are fully demonstrated.The first author acknowledges the Jafar Studentship during her PhD study at the University of Cambridge. The other authors acknowledge the support of the Major State Basic Research Development Program (973) of China (No. 2013CB036402), Open Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKHL1404; SKHL1409), Start-up Grant for the Young Teachers of Sichuan University (2014SCU11056) and National Science and Technology Support Plan (2012BAB0513B0).This is the accepted manuscript. The final version is available at http://link.springer.com/article/10.1007%2Fs11069-015-1726-6

Repetitive domain of Clostridium difficile toxin B exhibits cytotoxic effects on human intestinal epithelial cells and decreases epithelial barrier function

We have used recombinant repetitive domain of Clostridium difficile toxin B obtained from two different strains, rec-TcdB3(10463) and rec-TcdB3(8864) and a model intestinal epithelial cell line(s) to characterize their cytotoxic and cytopathic effect and influence on tight-junction organization. Both recombinant receptor binding domains caused intestinal epithelial cell damage, decreased transepithelial electrical resistance and induced translocation of ZO-1 from tight-junction proteins although less efficiently as holotoxins. Recombinant repetitive TcdB domains also caused stimulation of interleukin IL-8 synthesis in HT-29 cells. This is the first description of glucosyltransferase independent toxicity of TcdB and these C-terminal mediated effects may contribute to the pathophysiology of C difficile infection. (C) 2010 Elsevier Ltd. All rights reserved