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An in-depth understanding of the microstructure evolution of the thermotropic metamorphic layer is the basis for effectively suppressing surface and subsurface defects in electrical discharge machining (EDM) of Ti–6Al–4V. In this work, the thermo-hydraulic-metallographic coupling model with successive pulse was established for the first time, based on which the visual simulation of time-variant phase transformation in recast layer and heat-affected zone (HAZ) was achieved. Further, the microstructure distribution characteristics in the thermotropic metamorphic layer were investigated from the perspective of experimental observation. The results show that with the accumulation of successive pulse discharges, the temperature on the processed surface gradually increases while the overall temperature distribution tends to be relatively uniform. The microstructure of the EDMed surface is characterized by a layered distribution, in which the recast layer undergoes complete α ′-Ti (martensitic phase) transformation, and HAZ is composed of an upper layer with α ′-Ti and a lower layer with α + β + α ′ mixture. Meanwhile, it was revealed that the microstructure in the β grain of HAZ changed from a staggered distribution of the secondary α -Ti phase to a parallel distribution of the acicular α ′-Ti phase. A transition layer composed of cellular martensite was observed between the recast layer and HAZ, and the internal grain showed a change from parallel arrangement to staggered arrangement as the peak current increased to a relatively larger level. The martensite volume fraction and microhardness of the thermotropic metamorphic layer have also been verified to correlate to the peak current. The combined study of the thermo-hydraulic-metallographic coupling model and insights into microstructure characteristics were expected to provide theoretical references for predicting and controlling the surface integrity in EDM of Ti–6Al–4V. [ABSTRACT FROM AUTHOR]

Enzymes play a key role in natural mineralization, but their function is disabling in bone metabolism when patients suffer severe degenerations like hypophosphatasia. To regulate bone homeostasis, a self‐activating phosphorus‐rich system is proposed on calcium glycerophosphate (CaGP) modified polyurethane (PU) fibrous substrate, wherein ample enzyme catalytic domains are imported with intestinal alkaline phosphatase (IALP) chelating and activating by calcium in situ that is testified by chemical potential evaluation. Therefore, Ca‐bonding IALP catalyzes organophosphate to phosphate locally to achieve a calcified symbiotic state, regulating mineralization and accelerating osteoinduction in vitro and in vivo. The self‐activating enzyme system promotes early osteogenic differentiation and angiogenesis, resulting in rapid healing of cranial defect with a "long‐tail" effect compared to an enzyme‐assisted system. Transcriptomic and metabolomic analyses demonstrate positive associations with neovascularization and calcium/phosphorus metabolism, specifically upregulated glycerophospholipids and calcium ions in favor of osteogenic differentiation under cytokine‐free conditions. These results provide a potential enzyme‐activating therapy in bone homeostasis and regeneration. [ABSTRACT FROM AUTHOR]

Hemp seed is known for its content of fatty acids, proteins, and fiber, which contribute to its nutritional value. Here we studied the secondary metabolites of hemp seed aiming at identifying bioactive compounds that could contribute to its health benefits. This investigation led to the isolation of 4 new lignanamides, cannabisin M (2), cannabisin N (5), cannabisin O (8), and 3,3'-demethyl-heliotropamide (10), together with 10 known lignanamides, among which 4 was identified for the first time from hemp seed. Structures were established on the basis of NMR, HR-MS, UV, and IR as well as by comparison with the literature data. Lignanamides 2, 7, and 9-14 showed good antioxidant activity, among which 7, 10, and 13 also inhibited acetylcholinesterase in vitro. The newly identified compounds in this study add to the diversity of hemp seed composition, and the bioassays implied that hemp seed, with lignanamides as nutrients, may be a good source of bioactive and protective compounds.