PEG-grafted PVA Membrane and Its Blood Compatibility

Preparation and blood compatibility of different shape polyvinyl alcohol(PVA) membrane were investigated. Firstly, the tabular and tubular[polytetrafluoroethylene(PTFE) capillary as supporter] PVA membranes were prepared; then, methoxy polyethylene glycol(mPEG) was grafted onto the surface of the PVA membranes. The effects of the shape, structure and properties of the membrane surface on blood compatibility were studied in detail. The experiment results show that mPEG modified PVA membranes, especially mPEG modified tubular membrane, could availably repel the adhesion of the platelets. In addition, the anticoagulant mechanism of mPEG with a steric repulsion effectiveness was confirmed further via different grafting methods.     

Accelerating Gas Escape in Anion Exchange Membrane Water Electrolysis by Gas Diffusion Layers with Hierarchical Grid Gradients

At high current densities, gas bubble escape is the critical factor affecting the mass transport and performance of the electrolyzer. For tight assembly water electrolysis technologies, the gas diffusion layer (GDL) between the catalyst layer (CL) and the flow field plate plays a critical role in gas bubble removal. Herein, we demonstrate that the electrolyzer's mass transport and performance can be significantly improved by simply manipulating the structure of the GDL. Combined with 3D printing technology, ordered nickel GDLs with straight-through pores and adjustable grid sizes are systematically studied. Using an in situ high-speed camera, the gas bubble releasing size and resident time have been observed and analyzed upon the change of the GDL architecture. The results show that a suitable grid size of the GDL can significantly accelerate mass transport by reducing the gas bubble size and the bubble resident time. An adhesive force measurement has further revealed the underlying mechanism. We then proposed and fabricated a novel hierarchical GDL, reaching a current density of 2 A/cm² at a cell voltage of 1.95 V and 80 °C, one of the highest single-cell performances in pure-water-fed anion exchange membrane water electrolysis (AEMWE).     

Tailorable and Biocompatible Supramolecular-Based Hydrogels Featuring two Dynamic Covalent Chemistries

Dynamic covalent chemistry (DCC) has proven to be a valuable tool in creating fascinating molecules, structures, and emergent properties in fully synthetic systems. Here we report a system that uses two dynamic covalent bonds in tandem, namely disulfides and hydrazones, for the formation of hydrogels containing biologically relevant ligands. The reversibility of disulfide bonds allows fiber formation upon oxidation of dithiol-peptide building block, while the reaction between NH−NH₂ functionalized C-terminus and aldehyde cross-linkers results in a gel. The same bond-forming reaction was exploited for the “decoration” of the supramolecular assemblies by cell-adhesion-promoting sequences (RGD and LDV). Fast triggered gelation, cytocompatibility and ability to “on-demand” chemically customize fibrillar scaffold offer potential for applying these systems as a bioactive platform for cell culture and tissue engineering.     

Design and mechanism of agglomeration of aspirin crystals in pure solvents

Agglomeration with improved flowability for platy crystals is desirable in pharmaceutical downstream processing. The formation of agglomerates in pure solvents without the aid of bridging liquids is a convenient and low-cost method compared with complex spherical crystallization. In this work, the adhesion free energies between aspirin crystals in six solvents were calculated using Lifshitz-van der Waals acid-base theory to screen suitable solvents for agglomeration. The maximum stirring rate for agglomeration was determined by adhesion forces and dispersion forces. Then the agglomerates of plate-shaped aspirin were successfully prepared in acetone, methanol, ethanol, 2-propanol, and ethylene glycol without additives by simple cooling crystallization. The interactions between solvent and crystal surfaces were also used to explain the outcomes. A feasible mechanism for the agglomeration process of platy crystals was elucidated, involving the adhesion of dominant crystal facets at the beginning. The effect of stirring rate, cooling rate, and initial supersaturation on agglomeration degree and particle size of aspirin agglomerates were studied. The obtained aspirin agglomerates under the optimal conditions exhibited a uniform particle size distribution, a high agglomeration degree, and superior flowability.