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Geometric or electronic confinement of guests inside nanoporous hosts promises to deliver unusual catalytic or opto-electronic functionality from existing materials but is challenging to obtain particularly using metastable hosts, such as metal-organic frameworks (MOFs). Reagents (e.g. precursor) may be too large for impregnation and synthesis conditions may also destroy the hosts. Here we use thermodynamic Pourbaix diagrams (favorable redox and pH conditions) to describe a general method for metal-compound guest synthesis by rationally selecting reaction agents and conditions. Specifically we demonstrate a MOF-confined RuO2 catalyst (RuO2@MOF-808-P) with exceptionally high catalytic CO oxidation below 150 °C as compared to the conventionally made SiO2-supported RuO2 (RuO2/SiO2). This can be caused by weaker interactions between CO/O and the MOF-encapsulated RuO2 surface thus avoiding adsorption-induced catalytic surface passivation. We further describe applications of the Pourbaix-enabled guest synthesis (PEGS) strategy with tutorial examples for the general synthesis of arbitrary guests (e.g. metals, oxides, hydroxides, sulfides).

The large production volumes of commodity polyolefins (specifically, polyethylene, polypropylene, polystyrene, and poly-(vinyl chloride)), in conjunction with their low unit values and multitude of short-term uses, have resulted in a significant and pressing waste management challenge. Only a small fraction of these polyolefins is currently mechanically recycled, with the rest being incinerated, accumulating in landfills, or leaking into the natural environment. Since polyolefins are energy-rich materials, there is considerable interest in recouping some of their chemical value while simultaneously motivating more responsible end-of-life management. An emerging strategy is catalytic depolymerization, in which a portion of the C–C bonds in the polyolefin backbone is broken with the assistance of a catalyst and, in some cases, additional small molecule reagents. When the products are small molecules or materials with higher value in their own right, or as chemical feedstocks, the process is called upcycling. This review summarizes recent progress for four major catalytic upcycling strategies: hydrogenolysis, (hydro)-cracking, tandem processes involving metathesis, and selective oxidation. Key considerations include macromolecular reaction mechanisms relative to small molecule mechanisms, catalyst design for macromolecular transformations, and the effect of process conditions on product selectivity. Metrics for describing polyolefin upcycling are critically evaluated, and an outlook for future advances is described. [ABSTRACT FROM AUTHOR]

Objective: Neointimal hyperplasia is the primary mechanism underlying atherosclerosis and restenosis after percutaneous coronary intervention. Ketogenic diet (KD) exerts beneficial effects in various diseases, but whether it could serve as non-drug therapy for neointimal hyperplasia remains unknown. This study aimed to investigate the effect of KD on neointimal hyperplasia and the potential mechanisms., Methods and Results: Carotid artery balloon-injury model was employed in adult Sprague-Dawley rats to induce neointimal hyperplasia. Then, animals were subjected to either standard rodent chow or KD. For in-vitro experiment, impacts of β-hydroxybutyrate (β-HB), the main mediator of KD effects, on platelet-derived growth factor BB (PDGF-BB) induced vascular smooth muscle cell (VSMC) migration and proliferation were determined. Balloon injury induced event intimal hyperplasia and upregulation of protein expression of proliferating cell nuclear antigen (PCNA) and α-smooth muscle actin (α-SMA), and these changes were significantly ameliorated by KD. In addition, β-HB could markedly inhibit PDGF-BB induced VMSC migration and proliferation, as well as inhibiting expressions of PCNA and α-SMC. Furthermore, KD inhibited balloon-injury induced oxidative stress in carotid artery, indicated by reduced ROS level, malondialdehyde (MDA) and myeloperoxidase (MPO) activities, and increased superoxide dismutase (SOD) activity. We also found balloon-injury induced inflammation in carotid artery was suppressed by KD, indicated by decreased expressions of proinflammatory cytokines IL-1β and TNF-α, and increased expression of anti-inflammatory cytokine IL-10., Conclusion: KD attenuates neointimal hyperplasia through suppressing oxidative stress and inflammation to inhibit VSMC proliferation and migration. KD may represent a promising non-drug therapy for neointimal hyperplasia associated diseases.