Skin-like cryogel electronics from suppressed-freezing tuned polymer amorphization.

The sole situation of semi-crystalline structure induced single performance remarkably limits the green cryogels in the application of soft devices due to uncontrolled freezing field. Here, a facile strategy for achieving multifunctionality of cryogels is proposed using total amorphization of polymer. Through precisely lowering the freezing point of precursor solutions with an antifreezing salt, the suppressed growth of ice is achieved, creating an unusually weak and homogenous aggregation of polymer chains upon freezing, thereby realizing the tunable amorphization of polymer and the coexistence of free and hydrogen bonding hydroxyl groups. Such multi-scale microstructures trigger the integrated properties of tissue-like ultrasoftness (Young's modulus <10 kPa) yet stretchability, high transparency (~92%), self-adhesion, and instantaneous self-healing (<0.3 s) for cryogels, along with superior ionic-conductivity, antifreezing (-58 °C) and water-retention abilities, pushing the development of skin-like cryogel electronics. These concepts open an attractive branch for cryogels that adopt regulated crystallization behavior for on-demand functionalities.

A Novel Method for Observing Tumor Margin in Hepatoblastoma Based on Microstructure 3D Reconstruction.

Objective: We investigated three-dimensional (3 D) reconstruction for the assessment of the tumor margin microstructure of hepatoblastoma (HB). Methods: Eleven surgical resections of childhood hepatoblastomas obtained between September 2018 and December 2019 were formalin-fixed, paraffin-embedded, serially sectioned at 4 µm, stained with hematoxylin and eosin (every 19th and 20th section stained with alpha-fetoprotein and glypican 3), and the digital images of all sections were acquired at 100× followed by image registration using the B-spline based method with modified residual complexity. Reconstruction was performed using 3 D Slicer software. Results: The reconstructed orthogonal 3 D images clearly presented the internal microstructure of the tumor margin. The rendered 3 D image could be rotated at any angle. Conclusions: Microstructure 3 D reconstruction is feasible for observing the pathological structure of the HB tumor margin.

Selected Phase Separation Renders High Strength and Toughness to Polyacrylamide/Alginate Hydrogels with Large-Scale Cross-Linking Zones.

High water content usually contradicts the mechanics for hydrogels, and achieving both characteristics is extremely challenging. Herein, a novel confined-chain-aggregation (CCA) strategy is developed to fabricate ultrastrong and tough hydrogels without sacrificing their inherent water capacity. Based on the popular polyacrylamide/alginate (PAAm/Alg) system with a double network (DN), a poor solvent exchange is induced once PAAm is fully cross-linked but prior to ionic cross-linking of alginate. In this case, the alginate chains are restricted by the chemical PAAm network and undergo a confined-chain aggregation, which guarantees an interpenetrating network of both polymers and simultaneously generates micron-scale aggregates. In addition, after the subsequent water uptake, the accompanying formation of hydrogen bonds and metal-ligand coordination stabilizes the newly formed alginate aggregates, serving as large-scale cross-linking zones. However, the PAAm chains are anchored by the preformed cross-linking points and convert back to the uniformly distributed, high-water-content state, achieving a selected phase separation in a DN system. The combined CCA and hybrid cation cross-linking method gives mechanical strength and toughness to the PAAm/Alg hydrogels to reach approximately 30 and 5 times the traditional methods, respectively. This investigation provides a general strategy for the development of a new generation of double-network hydrogels, which will expand their application as structural materials for cartilage and soft robotics.

A self-reinforcing strategy enables the intimate interface for anisotropic alginate composite hydrogels.

Natural-derived hydrogels are expected as promising structural biomaterials, but the soft character severely limits their applications. Here, a facile yet effective strategy was developed to fabricate super-strong and tough alginate composite hydrogels via a self-reinforcing method. The strategy was based on the incorporation of alginate materials with distinctive anisotropic features (fibers, fabrics and aerogels) into the precursor solution of congeneric hydrogels, followed by the in situ ionic-crosslinking. Interestingly, triggered by the concentration difference, the cations-Ca2+ in reinforcing phase could diffuse into the interface and simultaneously chelate with alginate chains of both reinforcing phase and hydrogel matrix, acting as self-generating interfacial binders. Contributed by the intimate interface, the load was effectively transferred into the rigid reinforcing phase, and the hydrogels integrated them into a mechanical network. This research offers a new path to design the interface of polysaccharide composites without extra coupling agents.

Salinity Tolerance Mechanism of Economic Halophytes From Physiological to Molecular Hierarchy for Improving Food Quality.

Soil salinity is becoming the key constraints factor to agricultural production. Therefore, the plant especially the crops possessing capacities of salt tolerance will be of great economic significance. The adaptation or tolerance of plant to salinity stress involves a series of physiological, metabolic and molecular mechanisms. Halophytes are the kind of organisms which acquire special salt tolerance mechanisms to respond to the salt tress and ensure normal growth and development under saline conditions in their lengthy evolutionary adaptation, so understanding how halophytes respond to salinity stress will provide us with methods and tactics to foster and develop salt resistant varieties of crops. The strategies in physiological and molecular level adopted by halophytes are various including the changes in photosynthetic and transpiration rate, the sequestration of Na+ to extracellular or vacuole, the regulation of stomata aperture and stomatal density, the accumulation and synthesis of the phytohormones as well as the relevant gene expression underlying these physiological traits, such as the stress signal transduction, the regulation of the transcription factors, the activation and expression of the transporter genes, the activation or inhibition of the synthetases and so on. This review focuses on the research advances of the regulating mechanisms in halophytes from physiological to molecular, which render the halophytes tolerance and adaption to salinity stress.