Emitter clogging, a phenomenon commonly seen in reclaimed wastewater drip irrigation systems, is a severe obstacle to the wide applications and popularization of the irrigation technology. Some experiments showed that the emitter clogging was tightly related to biofilms formation attached to the irrigation system. In this paper, two types of wastewaters reclaimed respectively by fluidizedbed reactor (FBR) process and biological aerated filter (BAF) process were chosen as the experiment objects and then the effects of the average velocity on the growth and topography of biofilms attached to the irrigation laterals were studied. The parameters of biofilms reached their maximal values at a critical velocity of 0.45 m/s. The formation of biofilms was primarily controlled by the transport of the nutrients and suspended particles within the laterals when the average velocity is below the critical velocity, whereas it was primarily controlled by the hydraulic shear force when above the critical velocity. The main mechanism for emitter clogging was that the biofilms detached from laterals accumulated and grew at the inlets and outlets of emitters. A similar variation pattern was observed for both reclaimed wastewaters. However, the growth of biofilms for BAF process was more affected by the shear force than that for FBR process, since the nutrients and suspended particles for BAF were larger than those for FBR.

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A block combination genes (gx16-f) was designed and cloned for encoding GX16-F, which was derived from the crystalline domain (X: A, S, V or Y, GA: GAGAGA, GS: GAGAGS, GV: GAGAGV and GY: GAGAGY) and the amorphous domain (F=SGFGPVANGGSGEASSESDFGSSGFGPVANASSGEASSESDFAG) of Bombyx mori silk fibroin heavy chain. The combination genes were then cloned into a GST-tagged prokaryotic expression vector for expression of protein. Agarose gel electrophoresis analysis and DNA sequencing demonstrated that the combination gene encoding GX16-F was accurately cloned, and inserted into the expression vector successfully. The study would provide a technology to produce different structural polypeptides for studying the structurefunction relationships of silk fibroin.

As the depth and the length of the various underground cavern is increasing, the stability analysis of surrounding rock is very important. This paper first gives the analytical solution equation of the circular tunnel. About the city-gate water tunnel with no analytical solution, it can be solved by numerical method, which is based on the large finite element software ANSYS. The form of a calculation model for conveyance city-gate water tunnel was established. With the D - P criterion, it is nonlinear calculated for the computation of water conveyance tunnel. Then it is obtained that the stress characteristic and development of plastic zone characteristics of the surrounding rock of city-gate tunnel. It also gives the relationship between the development of plastic zone, plastic strain and coefficient of horizontal pressure, the internal friction angle. The last, it is analyzed the relationship between the different parameters and the plastic zone development of different parts of tunnel cavern. This result can provide technical reference for design and the tunnel construction.

Based on theories of finite element method, universal software ANSYS, by use of common software ANSYS as a platform, the influence degrees of transient temperature load and reservoir water load on arch dam stress are analyzed and computed. The result indicates that when the water level is same, the maximum tensile stress on arch dam has a close correlation with the variation of temperature, and the sensitivity of maximum tensile stress of arch dam for water temperature is higher than air temperature. The maximum tensile stress on arch dam does not correlate well with reservoir water level changes when the temperature is same. Through the non-dimensional processing on influencing factors which are temperature load and reservoir water level, the sensitivity of maximum tensile stress on arch dam for reservoir water pressure is higher than temperature load.