A complex mucosal barrier protects as the first line of defense the surface of the healthy intestinal tract from adhesion and invasion by luminal microorganisms. In this review, we provide an overview about the major ...A complex mucosal barrier protects as the first line of defense the surface of the healthy intestinal tract from adhesion and invasion by luminal microorganisms. In this review, we provide an overview about the major components of this protective system as for example an intact epithelium, the synthesis of various antimicrobial peptides (AMPs) and the formation of the mucus layer. We highlight the crucial importance of their correct functioning for the maintenance of a proper intestinal function and the prevention of dysbiosis and disease. Barrier disturbances including a defective production of AMPs, alterations in thickness or composition of the intestinal mucus layer, alterations of pattern-recognition receptors, defects in the process of autophagy as well as unresolved endoplasmic reticulum stress result in an inadequate host protection and are thought to play a crucial role in the pathogenesis of the inflammatory bowel diseases Crohn’s disease and ulcerative colitis.展开更多
The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline confi...The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived, The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.展开更多
基金Supported by Robert Bosch Foundation,Stuttgart,Germany
文摘A complex mucosal barrier protects as the first line of defense the surface of the healthy intestinal tract from adhesion and invasion by luminal microorganisms. In this review, we provide an overview about the major components of this protective system as for example an intact epithelium, the synthesis of various antimicrobial peptides (AMPs) and the formation of the mucus layer. We highlight the crucial importance of their correct functioning for the maintenance of a proper intestinal function and the prevention of dysbiosis and disease. Barrier disturbances including a defective production of AMPs, alterations in thickness or composition of the intestinal mucus layer, alterations of pattern-recognition receptors, defects in the process of autophagy as well as unresolved endoplasmic reticulum stress result in an inadequate host protection and are thought to play a crucial role in the pathogenesis of the inflammatory bowel diseases Crohn’s disease and ulcerative colitis.
基金supported by the National Natural Science Foundation of China (Grant No. 51009122)the Fundamental Research Funds for the Central Universities (Grant No. 2010QNA4030)the National High Technology Research and Development Program of China (863 Program, Grant No. 2006AA09A105)
文摘The safety of offshore pipeline has drawn a great deal of attention during deepwater installation due to the combined actions of high external pressure, axial tension, and bending moment. Meanwhile, the pipeline configuration has a remarkable effect on the structural behaviour of the tube. The special studies focus on the deepwater S-lay technique in the present paper. The stiffened catenary theory is applied to establish the static equilibrium governing differential equation of a pipe element, and the solution equations of the total pipeline configuration from a lay-barge over a stinger to the seabed are derived, The numerical iteration method for solving pipeline configuration is described in detail, and the corresponding program is developed to conduct the analysis of effects of various parameters such as laying water depth, pipe diameter, thickness of concrete weighted coating layer, stinger length, control strain, and axial tension on pipeline configuration. The results show that the laying water depth, the submerged weight of the pipe, and the axial tension are the critical factors influencing pipeline configuration. In addition, geometrical parameters of the stinger such as length, radius, and shape have an important effect on the pipe-laying capacity of the vessel. The validity of the program is further verified by means of a comparison with results obtained from the commercial finite element software OFFPIPE.
