Tight junction proteins are important for the maintenance and repair of the intestinal mucosal barrier. The present study investigated relationships among tight junction protein gene expres- sion, porcine epidemic diarrhea virus (PEDV) infection, and intestinal mucosal morphology in piglets. We compared the expression of six tight junction proteins (ZO-1, ZO-2, Occludin, Claudin-1, Claudin-4, and Claudin-5) between seven-day-old piglets infected with PEDV and normal piglets, as well as in PEDV-infected porcine intestinal epithelial cells (IPEC-J2). We also evaluated differences in mucosal morphology between PEDV-infected and normal piglets. The expression of six tight junction protein genes was lower in PEDV-infected piglets than in the normal animals. The expression of ZO-1, ZO-2, Occludin, and Claudin-4 in the intestine tissue was significantly lower (p<0.05) in PEDV-infected than in normal piglets. The expression of Claudin-5 in the jejunum was significantly lower in PEDV-infected piglets than in the normal animals (p<0.01). The expression of Claudin-1 and Claudin-5 genes in the ileum was signifi- cantly higher in PEDV-infected piglets than in normal piglets (p<0.01). Morphologically, the intestinal mucosa in PEDV-infected piglets exhibited clear pathological changes, including breakage and shedding of intestinal villi. In PEDV-infected IPEC-J2 cells, the mRNA expression of the six tight junction proteins showed a downward trend; in particular, the expression of the Occludin and Claudin-4 genes was significantly lower (p<0.01). These data suggest that the expression of these six tight junction proteins, especially Occludin and Claudin-4, plays an important role in maintaining the integrity of the intestinal mucosal barrier and resistance to PEDV infection in piglets.

Due to demand of tightness, the liquid tanks should be designed with particular care. In addition to the liquid pressure, the imposed concrete strains and thermal actions should be taken into consideration. Furthermore, the verification of the ULS in persistent design situation only is not sufficient. The crack control both in persistent situation as well as in early age transient one is necessary for determination of the reinforcement. In the beginning of the design process some assumptions, influencing the future tank performance must be made. First, the tightness class must be chosen, followed by formulation of conditions for crack width control. Next, the critical age of concrete, proper for early age transient situation should be assumed. This age determines the value of imposed strain on the one hand and the effective tensile concrete strength on the other. Then, it should be decided, if any reduction of the effective tensile strength would be applied (reduction associated with nonuniform imposed strain and reduction due to cracking under other combination of actions). Eventually, the decisions for structural analysis should be made, concerning the values of combination factors for actions both for ultimate and cracking limit state and the possible reduction of cross-section stiffness due to cracking caused by thermal actions in ULS.

The above-mentioned assumptions are listed and discussed in the paper. On the basis of the discussion the algorithm for crack control in concrete tanks is worked out and proposed. The issues are illustrated with practical example of cylindrical tank for liquid.

The paper is devoted to a bolted flanged joint with a flat ring gasket. Simple mathematical models of the flat ring gasket and the flange are formulated. Solutions to the models allowed determining numerically effective shapes of the flat ring and the flange. In the case of the gasket a minimal tension of the bolts was assumed as a criterion, while in the case of the flange the criterion of minimal angle of the flange rotation was applied. Results of the study, shown in the Figures, may serve for practical purposes in designing of pressure vessels and piping.

Cracks in concrete are inevitable but fortunately cracking enables the structures to get rid of its bending moment peaks. The reduction is due to the redistribution of the load induced moments and cut of the temperatureimposed moments. However, cracking becomes completely harmless if the crack widths are controlled properly by reinforcement. In this regard a method for crack width prediction is presented in this paper which thanks its reliability is widely accepted in the standards EN 13084, CICIND and DIN 1056.