Salt ions are multifunctional in living beings, in contrast to their limited efficiency in abiotic materials. Achieving the versatility of salt ions in synthetic materials is promising yet demanding. Here, we report that multivalent metallic ions can act multiple crucial roles in a polyacrylamide/sodium alginate (PAAm/SA) composite hydrogel system, inducing a quadruple effect that toughens and functionalizes the originally weak gel. Fixation of anisotropic structures (effect I), mechanical enhancement (effect II), conductivity improvement (effect III), as well as antifreezing and moisture retention properties (effect IV) simultaneously emerge in the gel, all of which are enabled by the ion effect. The resulting tough hydrogels exhibit excellent comprehensive properties that rival existing state-of-the-art hydrogels, promising a wide range of potential applications. As proof-of-concept demonstrations, extremely durable hydrogel-based soft electronic devices are developed, which operate stably even in harsh environments. We also prove that the ion effect can be induced by other multivalent metallic ions. This work highlights the versatility of salt ions in nonliving materials, providing a simple but enlightening idea for the development of all-around soft materials.

In this paper, an approach to realize all optical fractional Fourier transform through a high-nonlinear fiber and an optical pump is discussed. Based on a gradient index (GRIN) time lens which is realized through cross-phase modulation by a temporal quadratic pump pulse, it is possible to achieve all optical fractional Fourier transform. The order of the fractional Fourier transform varies along the fiber propagation distance. In a fixed fiber, it can be adjusted by simply changing the peak power of the pump pulse.