Fast photography and optical emission spectroscopy are implemented in a 5 mm neon gap dielectric barrier discharge(DBD) at atmospheric pressure with quartz glass used as the dielectric layer. Results show that it star...Fast photography and optical emission spectroscopy are implemented in a 5 mm neon gap dielectric barrier discharge(DBD) at atmospheric pressure with quartz glass used as the dielectric layer. Results show that it starts with a Townsend discharge and ends at a sub-normal glow discharge in neon DBD. Based on the Townsend discharge, the first ionization coefficient of neon is measured. The measurements are consistent with those at low pressure. Optical emission spectroscopy indicates that the spectra are mainly composed of atomic lines of neon, molecular bands and molecular ion bands originating from inevitable gas impurities(mainly nitrogen).Moreover, spectral lines emitted from atomic neon corresponding to the transitions(2p^5 3p→2p^5 3s) are predominant. Although the second positive system of N_2(C^3Π_u→B^3Π_g) is observed, their intensities are too weak compared with neon's spectrum. The molecular nitrogen ion line of 391.4 nm is observed. It reveals that Penning ionization between high energy neon excited states and the inevitable gas impurities plays an important role in the value of the αcoefficient.展开更多
Effects of photoionisation on the development and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage were studied via twodimensional particle-in-cell/Monte Carlo collision simu...Effects of photoionisation on the development and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage were studied via twodimensional particle-in-cell/Monte Carlo collision simulations.It was found that photoionisation has little effect at the beginning of the initial discharge.However,as the discharge channel gradually develops towards the anode,photoionisation shows greater impacts on the morphology of discharge but has little influence on the velocity of discharge development.Photoionisation does not appear to have a decisive effect on the growth trend of the highest energy of runaway electrons,but it does affect the change rate of the highest energy and overall distribution of electron energy,resulting in a higher proportion of energetic electrons.The difference in the distributions of the electron energy between the two cases,with and without considering photoionisation,can be attributed to the impact of photoionisation on the discharge morphology,which in turn distorted the electric field.The spatial density distributions of the electrons produced by photoionisation further explained the differences.The authors’results explicitly demonstrate the influence of photoionisation on the development and the electron runaway of the initial discharge under nanosecond pulse voltage,which provides more comprehensive knowledge for the atmospheric air gap nanosecond pulse discharge physics.展开更多
Graphene oxide(GO)exhibits good mechanical and physicochemical characteristics and has extensive application prospects in bone tissue engineering.However,its effect on angiogenesis is unclear,and its potential toxic e...Graphene oxide(GO)exhibits good mechanical and physicochemical characteristics and has extensive application prospects in bone tissue engineering.However,its effect on angiogenesis is unclear,and its potential toxic effects are heavily disputed.Herein,we found that nanographene oxide(NGO)synthesized by one-step water electrolytic oxidation is smaller and shows superior biocompatibility.Moreover,NGO significantly enhanced angiogenesis in calvarial bone defect areas in vivo,providing a good microenvironment for bone regeneration.Endothelial tip cell differentiation is an important step in the initiation of angiogenesis.We verified that NGO activates endothelial tip cells by coupling with lysophosphatidic acid(LPA)in serum via strong hydrogen bonding interactions,which has not been reported.In addition,the mechanism by which NGO promotes angiogenesis was systematically studied.NGO-coupled LPA activates LPAR6 and facilitates the formation of migratory tip cells via Hippo/Yes-associated protein(YAP)independent of reactive oxygen species(ROS)stimulation or additional complex modifications.These results provide an effective strategy for the application of electrochemically derived NGO and more insight into NGO-mediated angiogenesis.展开更多
In this work,the air dielectric barrier discharge plasma was applied to a model of protein human serum albumin to explore plasma‐mediated protein damage from a biomolecular perspective.Carbonylation and side chain mo...In this work,the air dielectric barrier discharge plasma was applied to a model of protein human serum albumin to explore plasma‐mediated protein damage from a biomolecular perspective.Carbonylation and side chain modifications of protein in solution were observed by Fourier transform infrared(FT‐IR)spectroscopy and mass spectrometry(MS).Protein backbone cleavage is proved by Bradford assay,sodium dodecyl sulphate–polyacrylamide gel electrophoresis,and MS.Typical fragments are in the range of 10–12 kDa.The decrease inα‐helix and increase inβ‐sheet indicated by FT‐IR are major protein secondary structure changes.Accordingly,a whole map of protein oxidative damage and structural changes in response to the plasma was postulated.展开更多
Concentrated growth factor(CGF)is a promising regenerative material that serves as a scaffold and adjunct growth factor for tissue engineering.The host immune response,particularly macrophage activity,plays a critical...Concentrated growth factor(CGF)is a promising regenerative material that serves as a scaffold and adjunct growth factor for tissue engineering.The host immune response,particularly macrophage activity,plays a critical role in injury repair and tissue regeneration.However,the biological effect of CGF on the immune response is not clear.To enrich the theoretical groundwork for clinical application,the present study examined the immunoregulatory role of CGF in macrophage functional activities in vitro.The CGF scaffold appeared as a dense fibrin network with multiple embedded leukocytes and platelets,and it was biocompatible with macrophages.Concentrated bioactive factors in the CGF extract enhanced THP-1 monocyte recruitment and promoted the maturation of suspended monocytes into adherent macrophages.CGF extract also promoted THP-1 macrophage polarization toward the M2 phenotype with upregulated CD163 expression,as detected by cell morphology and surface marker expression.A cytokine antibody array showed that CGF extract exerted a regulatory effect on macrophage functional activities by reducing secretion of the inflammatory factor interleukin-1b while inducing expression of the chemokine regulated on activation,normal T cell expressed and secreted.Mechanistically,the AKT signaling pathway was activated,and an AKT inhibitor partially suppressed the immunomodulatory effect of CGF.Our findings reveal that CGF induces a favorable immune response mediated by macrophages,which represents a promising strategy for functional tissue regeneration.展开更多
The similarity of gas discharge in low-pressure argon gaps between two plane-parallel electrodes was investigated by experiments,numerical simulations and theoretical analysis.It was found by the experiments that the ...The similarity of gas discharge in low-pressure argon gaps between two plane-parallel electrodes was investigated by experiments,numerical simulations and theoretical analysis.It was found by the experiments that the breakdown voltages depend not only on the product of gas pressure and gap length,but also on the aspect ratio of the gap,i.e.U_(b)=f(pd,d/r).It was theoretically proved that U_(b)=f(pd,d/r)is also a special case,the non-uniform electric field between plane-parallel electrodes,of similarity theorem of gas discharge.It was found by the experiments that there exist similar glow discharges only in two gaps with a limited scaled-down factor k.By theoretical analysis,it was explained that the forbidden processes such as the stepwise ionisation and the inelastic collision of the second kind violate the similarity of discharge as k increases,which was verified by the numerical simulations of the discharges with or without these two forbidden processes taken into account.展开更多
基金supported by Postdoctoral Project of Hebei University, National Natural Science Foundation of China (Nos. 11575050, 11875121, 51977057)Hebei Natural Science Fund (Nos. A2017201099, A2020201008)。
文摘Fast photography and optical emission spectroscopy are implemented in a 5 mm neon gap dielectric barrier discharge(DBD) at atmospheric pressure with quartz glass used as the dielectric layer. Results show that it starts with a Townsend discharge and ends at a sub-normal glow discharge in neon DBD. Based on the Townsend discharge, the first ionization coefficient of neon is measured. The measurements are consistent with those at low pressure. Optical emission spectroscopy indicates that the spectra are mainly composed of atomic lines of neon, molecular bands and molecular ion bands originating from inevitable gas impurities(mainly nitrogen).Moreover, spectral lines emitted from atomic neon corresponding to the transitions(2p^5 3p→2p^5 3s) are predominant. Although the second positive system of N_2(C^3Π_u→B^3Π_g) is observed, their intensities are too weak compared with neon's spectrum. The molecular nitrogen ion line of 391.4 nm is observed. It reveals that Penning ionization between high energy neon excited states and the inevitable gas impurities plays an important role in the value of the αcoefficient.
基金National Natural Science Foundation of China,Grant/Award Number:52077117Tsinghua University Initiative Scientific Research ProgramState Key Laboratory of Power System and Generation Equipment,Grant/Award Number:SKLD21M06。
文摘Effects of photoionisation on the development and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage were studied via twodimensional particle-in-cell/Monte Carlo collision simulations.It was found that photoionisation has little effect at the beginning of the initial discharge.However,as the discharge channel gradually develops towards the anode,photoionisation shows greater impacts on the morphology of discharge but has little influence on the velocity of discharge development.Photoionisation does not appear to have a decisive effect on the growth trend of the highest energy of runaway electrons,but it does affect the change rate of the highest energy and overall distribution of electron energy,resulting in a higher proportion of energetic electrons.The difference in the distributions of the electron energy between the two cases,with and without considering photoionisation,can be attributed to the impact of photoionisation on the discharge morphology,which in turn distorted the electric field.The spatial density distributions of the electrons produced by photoionisation further explained the differences.The authors’results explicitly demonstrate the influence of photoionisation on the development and the electron runaway of the initial discharge under nanosecond pulse voltage,which provides more comprehensive knowledge for the atmospheric air gap nanosecond pulse discharge physics.
基金This study was supported by the National Natural Science Foundation of China(No.52072167,81900989)the Natural Science Foundation of Guangdong Province(2019A1515011980)the Guangdong Basic and Applied Basic Research Foundation(2019A1515110088).
文摘Graphene oxide(GO)exhibits good mechanical and physicochemical characteristics and has extensive application prospects in bone tissue engineering.However,its effect on angiogenesis is unclear,and its potential toxic effects are heavily disputed.Herein,we found that nanographene oxide(NGO)synthesized by one-step water electrolytic oxidation is smaller and shows superior biocompatibility.Moreover,NGO significantly enhanced angiogenesis in calvarial bone defect areas in vivo,providing a good microenvironment for bone regeneration.Endothelial tip cell differentiation is an important step in the initiation of angiogenesis.We verified that NGO activates endothelial tip cells by coupling with lysophosphatidic acid(LPA)in serum via strong hydrogen bonding interactions,which has not been reported.In addition,the mechanism by which NGO promotes angiogenesis was systematically studied.NGO-coupled LPA activates LPAR6 and facilitates the formation of migratory tip cells via Hippo/Yes-associated protein(YAP)independent of reactive oxygen species(ROS)stimulation or additional complex modifications.These results provide an effective strategy for the application of electrochemically derived NGO and more insight into NGO-mediated angiogenesis.
基金This work was funded by the National Natural Science Foundation of China(52041701)Tsinghua University-Peking Union Medical College Hospital Initiative Scientific Research Programme(20191080604)Tsinghua University Spring Breeze Fund(2020Z99CFG007).
文摘In this work,the air dielectric barrier discharge plasma was applied to a model of protein human serum albumin to explore plasma‐mediated protein damage from a biomolecular perspective.Carbonylation and side chain modifications of protein in solution were observed by Fourier transform infrared(FT‐IR)spectroscopy and mass spectrometry(MS).Protein backbone cleavage is proved by Bradford assay,sodium dodecyl sulphate–polyacrylamide gel electrophoresis,and MS.Typical fragments are in the range of 10–12 kDa.The decrease inα‐helix and increase inβ‐sheet indicated by FT‐IR are major protein secondary structure changes.Accordingly,a whole map of protein oxidative damage and structural changes in response to the plasma was postulated.
基金supported by the National Natural Science Foundation of China(81900989,81870786)the Guangdong Basic and Applied Basic Research Foundation(2021A1515012475)the China Postdoctoral Science Foundation(2020M672548).
文摘Concentrated growth factor(CGF)is a promising regenerative material that serves as a scaffold and adjunct growth factor for tissue engineering.The host immune response,particularly macrophage activity,plays a critical role in injury repair and tissue regeneration.However,the biological effect of CGF on the immune response is not clear.To enrich the theoretical groundwork for clinical application,the present study examined the immunoregulatory role of CGF in macrophage functional activities in vitro.The CGF scaffold appeared as a dense fibrin network with multiple embedded leukocytes and platelets,and it was biocompatible with macrophages.Concentrated bioactive factors in the CGF extract enhanced THP-1 monocyte recruitment and promoted the maturation of suspended monocytes into adherent macrophages.CGF extract also promoted THP-1 macrophage polarization toward the M2 phenotype with upregulated CD163 expression,as detected by cell morphology and surface marker expression.A cytokine antibody array showed that CGF extract exerted a regulatory effect on macrophage functional activities by reducing secretion of the inflammatory factor interleukin-1b while inducing expression of the chemokine regulated on activation,normal T cell expressed and secreted.Mechanistically,the AKT signaling pathway was activated,and an AKT inhibitor partially suppressed the immunomodulatory effect of CGF.Our findings reveal that CGF induces a favorable immune response mediated by macrophages,which represents a promising strategy for functional tissue regeneration.
基金the National Natural Science Foundation of China under contracts 51477087 and 51377095the Foundation for the Author of National Excellent Doctoral Dissertation of PR China under Contract 201336 as well as by Fok Ying Tung Education Foundation under Contract 2142019.
文摘The similarity of gas discharge in low-pressure argon gaps between two plane-parallel electrodes was investigated by experiments,numerical simulations and theoretical analysis.It was found by the experiments that the breakdown voltages depend not only on the product of gas pressure and gap length,but also on the aspect ratio of the gap,i.e.U_(b)=f(pd,d/r).It was theoretically proved that U_(b)=f(pd,d/r)is also a special case,the non-uniform electric field between plane-parallel electrodes,of similarity theorem of gas discharge.It was found by the experiments that there exist similar glow discharges only in two gaps with a limited scaled-down factor k.By theoretical analysis,it was explained that the forbidden processes such as the stepwise ionisation and the inelastic collision of the second kind violate the similarity of discharge as k increases,which was verified by the numerical simulations of the discharges with or without these two forbidden processes taken into account.
