Adhesive hydrogels are promising to be explored as biomedical sealants, hemostatic agents, and glues in promoting wound healing and tissue regeneration. However, it is challenging to engineer a hydrogel combining instant robust adhesion and high strength. Herein, a high‐strength instantly self‐adhesive organic–inorganic hybrid (OIH) hydrogel by a one‐pot radical polymerization of N‐acryloyl 2‐glycine (ACG), biocompatible glycine derivative vinyl monomer with addition of hydroxyapatite (HAp), naturally occurring mineral is designed and fabricated. The hydrogen bonding from side chain of poly(N‐acryloyl 2‐glycine) (PACG), carboxyl‐Ca2+ ionic crosslinking together with PACG chain‐HAp physical interactions contribute to automatic self‐repairing high mechanical properties. Importantly, this OIH hydrogel exhibits robust adhesion to diverse substrates, presumably due to synergistic interactions of carboxyl with the substrate surface and the enhanced contact of PACG chains to adherent surfaces facilitated by HAp nanoparticles. Remarkably, the PACG‐HAp OIH hydrogels can instantly self‐adhere to the soft tissues with adhesion strength of 105 kPa, and anastomose the broken intestines, meanwhile promoting wound healing and stopping bleeding. The OIH hydrogel is autolytic in the body without eliciting inflammatory reaction. Further, the ready‐to‐use PACG‐HAp adhesive hydrogel can be properly stored for a long time. This novel hydrogel will find an appealing application as a new adhesive for emergency self‐rescue.
In this study, we demonstrate that dipole-dipole interaction can be employed to not only tremendously enhance the mechanical properties of hydrogel, but also impart the gel to an amazing ability to memorize two temporary shapes. Cross-linked hydrogels synthesized by copolymerization of acrylonitrile, a dipole-dipole containing monomer and hydrophilic comonomer are shown to exhibit triple shape memory (SM) triggered by the dynamic association and dissociation of dipole-dipole pairing between cynao groups uniquely responding to zinc ion species and concentration. This approach contributes to design and fabrication of novel SM hydrogels in a distinct way from conventional SM materials.
Fourier transform spectrometers (FTS), mostly working in infrared (IR) or near infrared (NIR) range, provide a variety of chemical or material analysis with high sensitivity and accuracy and are widely used in public safety, environmental monitoring and national border security, such as explosive detection. However, because of being bulky and expensive, they are usually used in test centers and research laboratories. Miniaturized FTS have been developed rapidly in recent years, due to the increasing demands. Using micro-electromechanical system (MEMS) micromirrors to replace the movable mirror in a conventional FTS system becomes a new realm. This paper first introduces the principles and common applications of conventional FTS, and then reviews various MEMS based FTS devices.
The process of development and calibration for the first Moon-based extreme ultraviolet (EUV) camera to observe Earth's plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mechanism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6 nm. The field of view is 14.7 • with an angular resolution of 0.08 • , and the sensitivity of the camera is 0.11 count s −1 Rayleigh −1. The geometric calibration, the absolute photometric calibration and the relative photometric calibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.
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