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Non-thermal plasma activation promotes CO2 conversion over Ni catalysts supported on BETA zeolite via multiple reaction mechanisms.

For large segmental bone defects, porous titanium scaffolds have some advantages, however, they lack electrical activity which hinders their further use. In this study, a barium titanate (BaTiO 3 ) piezoelectric ceramic was used to modify the surface of a porous Ti6Al4V scaffold (pTi), which was characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and roughness and water contact angle analyses. Low intensity pulsed ultrasound (LIPUS) was applied in vitro and in vivo study. The activity of bone marrow mesenchymal stem cells, including adhesion, proliferation, and gene expression, was significantly superior in the BaTiO 3 /pTi, pTi + LIPUS, and BaTiO 3 /pTi + LIPUS groups than in the pTi group. The activity was also higher in the BaTiO 3 /pTi + LIPUS group than in the BaTiO 3 /pTi and pTi + LIPUS groups. Additionally, micro-computed tomography, the mineral apposition rate, histomorphology, and the peak pull-out load showed that these scaffold conditions significantly enhanced osteogenesis and osseointegration 6 and 12 weeks after implantation in large segmental bone defects in the radius of rabbits compared with those resulting from the pTi condition. Consequently, the improved osteogenesis and osseointegration make the BaTiO 3 /pTi + LIPUS a promising method to promote bone regeneration in large segmental bone defects for clinical application.

ZSM-5 zeolite nanoboxes with accessible mesomicro-pore architecture and strong acid sites are important in relevant heterogeneous catalysis suffering from mass transfer limitations and weak acidities.R ational design of parent zeolites with concentrated and non-protective coordination of Al species can facilitate post-synthetic treatment to produce mesoporous ZSM-5 nanoboxes.I nt his work, as imple and effective method was developed to convert parent MFI zeolites with tetrahedral extra-framework Al into Al-enriched mesoporous ZSM-5 nanoboxes with low silicon-to-aluminium ratios of % 16. The parent MFI zeolite was prepared by rapid ageing of the zeolite sol gel synthesis mixture.The accessibility to the meso-micro-porous intra-crystalline network was probed systematically by comparative pulsed field gradient nuclear magnetic resonance diffusion measurements,w hich, together with the strong acidity of nanoboxes,provided superb catalytic activity and longevity in hydrocarbon cracking for propylene production.

Plasma-catalysis systems are complex and require further understanding to advance the technology. Herein, CO poisoning in CO2 hydrogenation over supported ruthenium (Ru) catalysts in a nonthermal plasma (NTP)-catalysis system was investigated by a combined kinetic and diffuse reflectance infrared Fourier transform spectroscopy–mass spectrometry (DRIFTS–MS) study and compared with the thermal catalytic system. The relevant findings suggest the coexistence of the Langmuir–Hinshelwood and Eley–Rideal mechanisms in the NTP-catalysis. Importantly, comparative study of CO poisoning of the Ru catalyst was performed under the thermal and NTP conditions, showing the advantage of the hybrid NTP-catalysis system over the thermal counterpart to mitigate CO poisoning of the catalyst. Specifically, compared with the CO poisoning in thermal catalysis due to strong CO adsorption and associated metal sintering, in situ DRIFTS–MS analysis revealed that the collisions of reactive plasma-derived species in NTP-catalysis could remove the strongly adsorbed carbon species to recover the active sites for CO2 activation. Thus, the NTP-catalysis was capable of preventing CO poisoning of the Ru catalyst in CO2 hydrogenation. Additionally, under the NTP conditions, the NTP-enabled water-gas shift reaction of CO with H2O (which was produced by CO/CO2 hydrogenation) shifted the equilibrium of CO2 hydrogenation toward CH4 production.

A systematic study of Ni supported on metal-organic frameworks (MOFs) catalyst (i.e., 15Ni/UiO-66) for catalytic CO 2 hydrogenation under nonthermal plasma (NTP) conditions was presented. The catalyst outperformed other catalysts based on conventional supports such as ZrO 2 , representing highest CO 2 conversion and CH 4 selectivity at about 85 and 99%, respectively. We found that the turnover frequency of the NTP catalysis system (1.8 ± 0.02 s −1) has a nearly twofold improvement compared with the thermal catalysis (1.0 ± 0.06 s −1). After 20 hr test, XPS and HRTEM characterizations confirmed the stability of the 15Ni/UiO-66 catalyst in the NTPactivated catalysis. The activation barrier for the NTP-activated catalysis was calculated as~32 kJ mol −1 , being lower than the activation energy of the thermal catalysis (~70 kJ mol −1). In situ DRIFTS characterization confirmed the formation of multiple carbonates and formates on catalyst surface activated by NTP, surpassing the control catalysts (e.g., 15Ni/α-Al 2 O 3 and 15Ni/ZrO 2).

Bone defect repair at load-bearing sites is a challenging clinical problem for orthopedists. Defect reconstruction with implants is the most common treatment; however, it requires the implant to have good mechanical properties and the capacity to promote bone formation. In recent years, the piezoelectric effect, in which electrical activity can be generated due to mechanical deformation, of native bone, which promotes bone formation, has been increasingly valued. Therefore, implants with piezoelectric effects have also attracted great attention from orthopedists. In this study, we developed a bioactive composite scaffold consisting of BaTiO3, a piezoelectric ceramic material, coated on porous Ti6Al4V. This composite scaffold showed not only appropriate mechanical properties, sufficient bone and blood vessel ingrowth space, and a suitable material surface topography but also a reconstructed electromagnetic microenvironment. The osteoconductive and osteoinductive properties of the scaffold were reflected by the proliferation, migration, and osteogenic differentiation of mesenchymal stem cells. The ability of the scaffold to support vascularization was reflected by the proliferation and migration of human umbilical vein endothelial cells and their secretion of VEGF and PDGF-BB. A well-established sheep spinal fusion model was used to evaluate bony fusion in vivo. Sheep underwent implantation with different scaffolds, and X-ray, micro-computed tomography, van Gieson staining, and elemental energy-dispersive spectroscopy were used to analyze bone formation. Isolated cervical angiography and visualization analysis were used to assess angiogenesis at 4 and 8 months after transplantation. The results of cellular and animal studies showed that the piezoelectric effect could significantly reinforce osteogenesis and angiogenesis. Furthermore, we also discuss the molecular mechanism by which the piezoelectric effect promotes osteogenic differentiation and vascularization. In summary, Ti6Al4V scaffold coated with BaTiO3 is a promising composite biomaterial for repairing bone defects, especially at load-bearing sites, that may have great clinical translation potential.