The global optimization of sensor locations for structural health monitoring systems is studied in this paper. First, the performance function based on damage detection is presented. Then, genetic algorithms (GAs) are adopted to search for the optimal locations of sensors. However, the simple GAs can result in infeasible solutions to the problem. Some improved strategies are presented in this paper, such as crossover based on identification code, mutation based on two gene bits, and improved convergence. The analytical results from the improved genetic algorithm are compared with the penalty function method and the forced mutation method. It is concluded that the convergence speed with the proposed improved genetic algorithm is faster than that with the penalty function method and the forced mutation method, and the result of placement optimization is better.

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Regulating cell migration dynamics is of significance in tissue engineering and regenerative medicine. A 3D scaffold was created to provide various topographies based on a poly­(ε-caprolactone) (PCL) self-induced nanohybrid shish-kebab structure, which consisted of aligned PCL nanofibers and spaced PCL crystal lamellae grown on the fibers. Electrospinning was applied followed by self-induced crystallization. The results resembled natural collagen fibrils in an extracellular matrix. This variable microstructure enabled control of cell adhesion and migration. The kebab size was controlled by initial PCL concentrations. The geometry of cells seeded on the fibers was less elongated, but the adhesion was more polarized with a higher nuclear shape index and faster migration speed. These results could aid in rapid endothelialization in tissue engineering.

This paper provides a method combining eco-friendly supercritical CO2 microcellular foaming and polymer leaching to fabricate small-diameter vascular tissue engineering scaffolds.

Polytetrafluoroethylene (PTFE) is one of the polymers extensively applied in biomedicine. However, the application of PTFE as a small-diameter vascular graft results in thrombosis and intimal hyperplasia because of the immune response. Therefore, improving the biocompatibility and anticoagulant properties of PTFE is a key to solving this problem. In this study, a hydroxyl group-rich surface was obtained by oxidizing a benzoin-reduced PTFE membrane. Then, chondroitin sulfate (CS), an anticoagulant, was grafted on the surface of the hydroxylated PTFE membrane using 3-aminopropyltriethoxysilane. The successful modification of the membrane in each step was demonstrated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Hydroxylation and the grafting of CS greatly increased the hydrophilicity and roughness of membrane samples. Moreover, the hydroxylated PTFE membrane enhanced the adhesion ability of endothelial cells, and the grafting of CS also promoted the proliferation of endothelial cells and decreased platelet adhesion. The results indicate that the PTFE membranes grafted with CS are able to facilitate rapid endothelialization and inhibit thrombus formation, which makes the proposed method outstanding for artificial blood vessel applications.

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316LN is a type of austenitic stainless steel whose grain refinement only depends on hot deformation. The true stress–strain curves of 316LN were obtained by means of hot compression experiments conducted at a temperature range of 900–1200°C and at a strain rate range of 0·001–10 s−1. The influence of deformation parameters on the microstructure of 316LN was analysed. Both the constitutive equation for 316LN and the model of grain size after dynamic recrystallisation were established, and the effect of different deformation conditions on the microstructure was analysed. The results show that the suitable working region is the one with a relatively higher deformation temperature and a lower strain rate, in which the dynamic recrystallisation is finely conducted. Moreover, the working region that should be avoided during hot deformation was indicated.

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