A linearly conforming point interpolation method (LC-PIM) is developed for 2D solid problems. In this method, shape functions are generated using the polynomial basis functions and a scheme for the selection of local supporting nodes based on background cells is suggested, which can always ensure the moment matrix is invertible as long as there are no coincide nodes. Galerkin weak form is adopted for creating discretized system equations, and a nodal integration scheme with strain smoothing operation is used to perform the numerical integration. The present LC-PIM can guarantee linear exactness and monotonic convergence for the numerical results. Numerical examples are used to examine the present method in terms of accuracy, convergence, and efficiency. Compared with the finite element method (FEM) using linear triangle elements and the radial point interpolation method (RPIM) using Gauss integration, the LC-PIM can achieve higher convergence rate and better efficiency.

Molecular recognition is fundamental to the specific interactions between molecules, of which the best known examples are antibody-antigen binding and complementary DNA hybridization. Reversible manipulation of the molecular recognition events is still a very challenging topic< and such studies are often performed at the molecular level. An important consideration is collection of changes at the molecular level to provide macroscopic observables. This research makes use of photo-responsive molecular recognition for the fabrication of novel photo-regulated dynamic materials. Specifically, a dynamic hydrogel was prepared by grafting azobenzene-tethered ssDNA and its complementary DNA to the hydrogel network. The macroscopic volume of the hydrogel can be manipulated through the photo-reversible DNA hybridization controlled by alternating irradiation of UV and visible light. The effects of synthetic parameters including the concentration of DNA, polymer monomer and permanent crosslinker are also discussed.