Biostable electronic materials that can maintain their super mechanical and conductive properties, even when exposed to biofluids, are the fundamental basis for designing reliable bioelectronic devices. Herein, cellulose-derived conductive 2D bio-nanosheets as electronic base materials are developed and assembled into a conductive hydrogel with ultra-high biostability, capable of surviving in harsh physiological environments. The bio-nanosheets are synthesized by guiding the in situ regeneration of cellulose crystal into a 2D planar structure using the polydopamine-reduced-graphene oxide as supporting templates. The nanosheet-assembled hydrogel exhibits stable electrical and mechanical performances after undergoing aqueous immersion and in vivo implantation. Thus, the hydrogel-based bioelectronic devices are able to conformally integrate with the human body and stably record electrophysiological signals. Owing to its tissue affinity, the hydrogel further serves as an "E-skin," which employs electrotherapy to aid in the faster healing of chronic wounds in diabetic mice through transcutaneous electrical stimulation. The nanosheet-assembled biostable, conductive, flexible, and cell/tissue affinitive hydrogel lays a foundation for designing electronically and mechanically reliable bioelectronic devices.

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Achieving strength-ductility synergy of hot-stamping steel via microalloying technology has attracted great attention due to their pronounced precipitation strengthening. Nevertheless, the precipitation behaviours and characteristics have not been clearly unveiled. In this work, the effects of V content on the microstructure and mechanical properties of 1800 MPa grade hot-stamping steel are systematically studied. Massive V contained precipitates develop after hot-rolling and coiling, which refine the martensitic microstructure and retain in the matrix after austenitizing and quenching. The refined martensite with massive precipitates is responsible for the good mechanical properties. Generally, the tensile strength decreases slightly with increasing V content from 0.04% to 0.2%, as V consumes C in the martensite matrix by forming carbides and promoting precipitate coarsening.

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