Metal–organic frameworks (MOFs) as electrocatalysts for oxygen evolution reaction (OER) typically suffer from fast degradation under harsh electrolyte conditions, impeding their practical use in industrial electrolyzers. Besides, the evolution of catalytic centers in MOFs and the related influence on their performance along the progress of reaction have rarely been studied. Here, we report a type of structurally stable bimetallic FeNi-MOF nanoarrays with self-optimized electrocatalytic activities in the oxygen production. Such a unique dynamic phenomenon is related with the gradual valence increments of Fe ions in MOFs, which trigger the continuous performance improvement before reaching an optimal steady state. Apart from the intact crystalline structures upon cycling, these FeNi-MOFs achieve low overpotentials of 239 and 308 mV at the current densities of 50 and 200 mA cm–2, respectively, and show durable operation for over 1033 h (>43 days) at 100 mA cm–2 and for another 200 h at 500 mA cm–2. A direct comparison of isostructural and single crystalline Fe-MOFs and Ni-MOFs resolves higher activities of Fe sites in the bimetallic MOFs, which are corroborated by theoretical calculations. The Fe–O bond covalency increment during Fe oxidation enhances the proton–electron transfers with the oxygen 2p-band closer to the Fermi level, thereby expediting the OER process. This work provides deep insights into the understanding of catalytic processes in heterometallic MOFs.

Controlled growth of metal–organic frameworks (MOFs) nanocrystals on requisite surfaces is highly desired for myriad applications related to catalysis, energy, and electronics. Here, this challenge is addressed by overlaying arbitrary surfaces with a thermally evaporated metal layer to enable the well‐aligned growth of ultralong quasi‐2D MOF nanoarrays comprising cobalt ions and thiophenedicarboxylate acids. This interfacial engineering approach allows preferred chelation of carboxyl groups in the ligands with the metal interlayers, thereby making possible the fabrication and patterning of MOF nanoarrays on substrates of any materials or morphologies. The MOF nanoarrays grown on porous metal scaffolds demonstrate high electrocatalytic capability for water oxidation, exhibiting a small overpotential of 270 mV at 10 mA cm−2, or 317 mV at 50 mA cm−2 as well as negligible decay of performance within 30 h. The enhanced performance stems from the improved electron and ion transport in the hierarchical porous nanoarrays consisting of in situ formed oxyhydroxide nanosheets in the electrochemical processes. This approach for mediating the growth of MOF nanoarrays can serve as a promising platform for diverse applications.

Icariin (ICA) is a pharmacologically active flavonoid glycoside that shows promise in the treatment and prevention of osteoporosis (OP). However, the mechanisms underlying the anti-osteoporotic effects of ICA remain largely unclear. The present study used quantitative polymerase chain reaction, western blot and immunohistochemical analysis to examine the effects of ICA on several key targets in the Notch signaling pathway in bone tissue in ovariectomized rats. It was observed that ICA has a pronounced beneficial effect on OP rats and inhibits the expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα) and fatty acid-binding protein 4 (FABP4) mRNA. In addition, it was identified that ICA downregulates the expression of notch1 intracellular domain (N1ICD) and Jagged1 proteins in bone tissue, and suppresses the effect of N1ICD on Notch2 mRNA expression. It is proposed that ICA inhibits the differentiation of mesenchymal stem cells into adipocytes by inhibiting the expression of PPARγ, C/EBPα and FABP4 mRNA via the Notch signaling pathway. In addition, it is proposed that ICA inhibits the expression of Notch2 mRNA by suppressing the effect of N1ICD. In conclusion, the results provide further mechanistic evidence for the clinical efficacy of ICA in the treatment of OP.

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The effects of osteoporosis can largely be reduced by treatment with Epimedium most likely through a mechanism associated with several neuropeptides involved in regulation of the brain/spinal cord/bone axis. These novel results contribute to existing literature regarding the possible mechanisms of habitual use of Epimedium in the treatment of osteoporosis.