Bone marrow mesenchymal stem cells (BMMSCs) exert immunosuppressive activity in transplantation, and heme oxygenase-1 (HO-1) enhances their immunomodulatory effects. The aim of this study was to determine whether HO-1-transduced BMMSCs (HO-1/MSCs) improve rat liver transplantation (LTx) outcomes. Orthotopic LTx rejection models were treated with HO-1/MSCs, BMMSCs, HO-1, or normal saline, respectively. Our results showed a significant improvement in survival rates in the HO-1/BMMSCs group compared to the control groups. At all time points, liver function marker levels in the HO-1/MSCs group were significantly lower than in the other three groups; on POD 1, 7, and 14, the degree of rejection and apoptotic cells was significantly less in the HO-1/MSCs group than in the other three groups. Interleukin- (IL-) 10 and transforming growth factor-β levels were significantly increased, while IL-2, IL-6, IL-17, IL-23, tumor necrosis factor-α, and interferon-γ levels were significantly decreased in the HO-1/MSCs group when compared to the other groups. Splenocyte Tregs were significantly increased by HO-1/MSCs compared with controls on POD 3, 5, 7, 10, 14, and 28. Summarily, we provide evidence that HO-1/MSCs improved allogeneic LTx outcomes by attenuating inflammatory responses and acute cellular rejection, as well as enhanced immunomodulatory effects compared with BMMSCs.

The perfluoronitrile C4F7N is considered a promising SF6-alternative in high-voltage gas-insulated apparatus, thanks to its high dielectric strength and low global warming potential. However, a complete and consistent set of electron-neutral collision cross-sections of C4F7N is still lacking, which hinders relevant plasma modelling. In this contribution, the available electron-neutral collision cross-sections of C4F7N are first compiled and assessed. The initial cross-sections are adjusted iteratively by the electron swarm method to determine a complete and self-consistent cross-section set of C4F7N for the first time. The set is validated by a systematic comparison of electron swarm parameters between Boltzmann equation analysis and experimental measurements in pure C4F7N as well as C4F7N/N2 and C4F7N/Ar mixtures. The proposed cross-section set of C4F7N will be made available to the community in the LXCat database. It will be of particular importance for applications with an emphasis on the discharge mechanisms of this novel gas.

Environmental considerations are increasingly taking a front seat in all arenas of our daily lives. Among the major concerns are greenhouse gases and the resulting global warming problem. Although sulfur hexafluoride (SF6) is the most widely used insulation and arc-interruption medium in electrical power equipment, it is an extremely potent greenhouse gas with a very high global warming potential (GWP). Hence, the global power industry has been actively seeking SF6-alternative gases for decades. In recent years, much progress has been made in developing promising new gases that have dielectric properties similar to, or even better than, SF6 but with much lower GWPs. Many engineering-oriented tests have been performed on the technical performance of these gases and some manufacturers have announced their application in pilot projects. However, their large-scale application still seems premature, in particular because of the lack of some critical fundamental physicochemical information for these relatively novel compounds. To provide a better understanding of these SF6-alternative gases, this paper reviews the recent advances in obtaining their fundamental physicochemical properties, emphasizing basic data calculations and fundamental experiments. The most important properties are analyzed comprehensively. These include the basic physical properties of arc plasmas formed from the gases, decomposition characteristics, materials compatibilities, swarm parameters, cross-sections and some dielectric properties. Finally, perspectives on current research and future research directions are presented.

In high-voltage direct current (HVDC) transmission systems, electric charge accumulates on insulator surfaces, causing surface electric field distortion and flashover voltage reduction. Therefore, studying a material that can improve the insulator surface insulation strength is of great engineering value. In this work, several types of metal nanoparticles with different particle sizes and concentrations are doped into epoxy resin. The experimental phenomena enables some interesting conclusions: when no agglomeration of doped nanoparticles occurs, a higher doping concentration provides a better insulation performance. The larger the doping particle size is, the lower the insulation performance. Additionally, under the same conditions, different types of metal nanoparticles lead to slightly different results after doping. Especially after doping with low concentration (approximately 120 parts per million (ppm)) and small particle size (approximately 10 nm) nanocopper particles, the insulator surface charge accumulation was effectively suppressed, and the flashover voltage was significantly improved. Our analysis suggests that it may be related to the single-electron tunneling phenomenon. Relevant results provide a new way to improve the surface insulation strength of insulators in the future.

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In recent years, the C4F7N/CO2 gas mixture has been considered one of the most promising candidates to replace the strong greenhouse gas SF6 in high-voltage power equipment. However, there are few studies on the thermal stability of the C4F7N/CO2 gas mixture. In this paper, the characteristics and mechanism of the thermal decomposition of C4F7N/CO2 gas mixture are analyzed by both experiment and calculation. Gas chromatography-mass spectrometry (GC-MS) is applied to detect the decomposition products at different temperatures and pressures. The measurements show that the C4F7N/CO2 mixture undergoes significant decomposition above about 700°C and the main products are CO, C2F6, C3F6, C3F8, C2F3N, C3F5N and C2N2. Previous studies have explored the possible decomposition pathways of C4F7N and predicted the free radicals produced after the decomposition. However, the subsequent processes in which the free radicals recombine and form stable products have not been considered. In this study, both the decomposition and recombination pathways are considered and the corresponding reaction rate constants are calculated. Based on this, precise chemical kinetic composition results at steady state during the thermal decomposition of C4F7N/CO2 mixture are obtained. Further, the influences of pressure and temperature on the decomposition products are theoretically investigated. It is also found that C4F7N/CO2 gas mixtures are more stable under higher pressures. The results provide an important reference for the engineering application of C4F7N/CO2 gas mixtures.

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Recently, C4F7N mixtures have attracted attention as a promising SF6 alternative due to their low global warming potential and excellent electrical performance. In this study, we introduce a newly built experimental setup for pulsed Townsend measurements as well as the physical model for the acquisition of electron swarm parameters. The effective ionization rate coefficients, electron drift velocity, and density-normalized longitudinal diffusion coefficients in C4F7N and its mixtures with CO2 and N2 were obtained. The reduced critical electric field for pure C4F7N at 100 Pa is determined to be 1002 Td, while it decreases with increasing pressure because of the effect of ion kinetics during the discharge process. C4F7N shows good synergism with CO2 and N2. To have a dielectric strength equivalent to that of SF6, the mixing ratio of C4F7N in its mixtures with CO2 and N2 should be 18% and 12%, respectively. The results provide fundamental data for modeling discharges in C4F7N and its mixtures.