Simultaneously manipulating multiple physical fields plays an important role in the increasingly complex integrated systems,aerospace equipment,biochemical productions,etc.For on-chip systems with high integration lev...Simultaneously manipulating multiple physical fields plays an important role in the increasingly complex integrated systems,aerospace equipment,biochemical productions,etc.For on-chip systems with high integration level,the precise and efficient control of the propagation of electromagnetic waves and heat fluxes simultaneously is particularly important.In this study,we propose a graphical designing method(i.e.,thermal-electromagnetic surface transformation)based on thermal-electromagnetic null medium to simultaneously control the propagation of electromagnetic waves and thermal fields according to the pre-designed paths.A thermal-electromagnetic cloak,which can create a cloaking effect on both electromagnetic waves and thermal fields simultaneously,is designed by thermal-electromagnetic surface transformation and verified by both numerical simulations and experimental measurements.The thermal-electromagnetic surface transformation proposed in this study provides a new methodology for simultaneous controlling on electromagnetic and temperature fields,and may have significant applications in improving thermal-electromagnetic compatibility problem,protecting of thermal-electromagnetic sensitive components,and improving efficiency of energy usage for complex onchip systems.展开更多
Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, ...Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, the mRNA and metabolome sequencing of P. hopeiensis flower organs exposed to different low temperatures were performed to identify changes of genes and metabolites in response to low-temperature stress. A total of 4 851 differentially expressed genes(DEGs) were identified. Trend analysis showed that these DEGs were significantly enriched in profiles 19, 18, 7, 14, 1, 4 and 11. And the KEGG enrichment analysis showed that the DEGs in profile 18 were significantly enriched in flavone and flavonol biosynthesis. Besides, the expressed trends as well as GO and KEGG functional enrichment analyses of DEGs under cold and freezing stress showed significantly difference. Analyses of flavonoid-related pathways indicated that flavonoid structural genes had undergone significant changes. Correlation analysis showed that b HLH and MYB TFs may affect flavonoid biosynthesis by regulating structural gene expression. And PhMYB308 and PhMYB330 were likely candidate repressors of flavonoid biosynthesis by binding to a specific site in bHLH proteins. In total, 92 differentially accumulated metabolites(DAMs) were identified in P. hopeiensis flowers including 12 flavonoids. WGCNA results showed that coral 1, pink and brown 4 modules were closely associated with flavonoids and 11 MYBs and 15 bHLHs among the three modules may activate or inhibit the expression of 23 structural genes of flavonoid biosynthesis. Taken together, the results of this study provided a theoretical basis for further exploration of the molecular mechanisms of flavonoid biosynthesis and cold resistance of P. hopeiensis flower organs and our findings laid a foundation for further molecular breeding in cold-resistant pear varieties.展开更多
Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures....Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures.Here,an MgO-based magnetic tunnel junction(MTJ)is chosen rationally as the ferromagnetic constitution and a high-activity(001)-Pb(Mg_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)O_(3)(PMN-0.3PT)single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure.The shape of tunneling magnetoresistance(TMR)versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias.The E-field-controlled change in the TMR ratio is up to-0.27%without magnetic-field bias.Moreover,when a typical magnetic field(~±10 Oe)is applied along the minor axis of the MTJ,the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias.This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ.In addition,based on such a multiferroic heterostructure,a strain-gauge factor up to approximately 40 is achieved,which decreases further with a sign change from positive to negative with increasing magnetic fields.This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.展开更多
Polyetheretherketone(PEEK)has been an alternative material for titanium in bone defect repair,but its clinical application is limited by its poor osseointegration.In this study,a porous structural design and activated...Polyetheretherketone(PEEK)has been an alternative material for titanium in bone defect repair,but its clinical application is limited by its poor osseointegration.In this study,a porous structural design and activated surface modification were used to enhance the osseointegration capacity of PEEK materials.Porous PEEK scaffolds were manufactured via fused deposition modeling and a polydopamine(PDA)coating chelated with magnesium ions(Mg^(2+))was utilized on the surface.After surface modification,the hydrophilicity of PEEK scaffolds was significantly enhanced,and bioactive Mg^(2+)could be released.In vitro results showed that the activated surface could promote cell proliferation and adhesion and contribute to osteoblast differentiation and mineralization;the released Mg^(2+)promoted angiogenesis and might contribute to the formation of osteogenic H-type vessels.Furthermore,porous PEEK scaffolds were implanted in rabbit femoral condyles for in vivo evaluation of osseointegration.The results showed that the customized three-dimensional porous structure facilitated vascular ingrowth and bone ingrowth within the PEEK scaffolds.The PDA coating enhanced the interfacial osseointegration of porous PEEK scaffolds and the released Mg^(2+)accelerated early bone ingrowth by promoting early angiogenesis during the coating degradation process.This study provides an efficient solution for enhancing the osseointegration of PEEK materials,which has high potential for translational clinical applications.展开更多
Biodegradable polycaprolactone/β-tricalcium phosphate(PT)composites are desirable candidates for bone tissue engineering applications.A higherβ-tricalcium phosphate(TCP)ceramic content improves the mechanical,hydrop...Biodegradable polycaprolactone/β-tricalcium phosphate(PT)composites are desirable candidates for bone tissue engineering applications.A higherβ-tricalcium phosphate(TCP)ceramic content improves the mechanical,hydrophilic and osteogenic properties of PT scaffolds in vitro.Using a dynamic degradation reactor,we estab-lished a steady in vitro degradation model to investigate the changes in the physio-chemical and biological properties of PT scaffolds during degradation.PT46 and PT37 scaffolds underwent degradation more rapidly than PT scaffolds with lower TCP contents.In vivo studies revealed the rapid degradation of PT(PT46 and PT37)scaffolds disturbed macrophage responses and lead to bone healing failure.Macrophage co-culture assays and a subcutaneous implantation model indicated that the scaffold degradation process dynamically affected macro-phage responses,especially polarization.RNA-Seq analysis indicated phagocytosis of the degradation products of PT37 scaffolds induces oxidative stress and inflammatory M1 polarization in macrophages.Overall,this study reveals that the dynamic patterns of biodegradation of degradable bone scaffolds highly orchestrate immune responses and thus determine the success of bone regeneration.Therefore,through evaluation of the biological effects of biomaterials during the entire process of degradation on immune responses and bone regeneration are necessary in order to develop more promising biomaterials for bone regeneration.展开更多
A common method to examine the current-limiting performance of saturated iron-core fault current limiter(SI-FCL) in high-voltage direct-current transmission based on voltage source converter(VSC-HVDC) systems is to so...A common method to examine the current-limiting performance of saturated iron-core fault current limiter(SI-FCL) in high-voltage direct-current transmission based on voltage source converter(VSC-HVDC) systems is to solve differential equations based on the system fault transient characteristics and the equivalent inductance calculation equation. This method analyzes the fault current of the VSC-HVDC system in the time domain. However, it is computationally complex and cannot directly reflect the relationship between parameters and the currentlimiting effect of the SI-FCL.In this paper,the relationship between the magnetic flux density and magnetic field energy of the SI-FCL is analyzed. The energy exchange between the DC capacitor and the SI-FCL in the DC short circuit fault process is analyzed. From the perspective of electromagnetic energy conversion, the criterion for determining the current-limiting ability of the SI-FCL in the transient process is given based on the parameters of the SI-FCL and VSC-HVDC system. On this basis, the characteristics of the DC side fault current and the capacitor voltage when the SI-FCL has current-limiting ability are examined.Based on the parameters of the SI-FCL and VSC-HVDC system, a method for calculating the fault current peak value and capacitor voltage drop time is given. Finally, the accuracy of the analysis of the SI-FCL in the VSC-HVDC system based on the electromagnetic energy conversion mechanism is demonstrated through a case study and simulation results of the VSC-HVDC system with different SI-FCLs.展开更多
An optical funnel,which performs as a passive electromagnetic compressor,can guide electromagnetic waves from a wide inlet to a narrow outlet without reflectance/scattering and squeeze electromagnetic fields uniformly...An optical funnel,which performs as a passive electromagnetic compressor,can guide electromagnetic waves from a wide inlet to a narrow outlet without reflectance/scattering and squeeze electromagnetic fields uniformly to an air neck.In this study,an optical funnel is designed by precisely filling subwavelength ceramic blocks with a gradient refractive index inside a tapered waveguide.The gradient refractive index is designed by transformation optics,which is isotropic and all above unit,thus exhibiting a broadband feature.Due to the mechanism of impedance matching over the whole funnel,extremely low reflectance/scattering and stable enhancement of fields can be achieved.The field enhancement factor in different regions of the funnel(e.g.,in the air neck)can be flexibly designed just by modifying the funnel-width ratios.展开更多
A novel way to design arbitrarily shaped retro-reflectors by optics surface transformation is proposed. The entire design process consists of filling an optic-null medium between the input and output surfaces of the r...A novel way to design arbitrarily shaped retro-reflectors by optics surface transformation is proposed. The entire design process consists of filling an optic-null medium between the input and output surfaces of the retroreflector, on which the points have 180 deg reverse corresponding relations. The retro-reflector can be designed to be very thin(a planar structure) with high efficiency. The effective working angles of our retro-reflector are very large(from-80 deg to +80 deg), which can, in principle, be further extended. Layered metal plates and zero refractive index materials are designed to realize the proposed retro-reflector for a TM polarized beam.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 61971300, 12274317, 12374277, 61905208)Open Foundation of China-Belarus Belt and Road Joint Laboratory on Electromagnetic Environment Effect (No. ZBKF2022031202)+1 种基金Scientific and Technological Innovation Programs (STIP) of Higher Education Institutions in Shanxi (Nos. 2019L0159 and 2019L0146)2022 University Outstanding Youth Foundation of Taiyuan University of Technology
文摘Simultaneously manipulating multiple physical fields plays an important role in the increasingly complex integrated systems,aerospace equipment,biochemical productions,etc.For on-chip systems with high integration level,the precise and efficient control of the propagation of electromagnetic waves and heat fluxes simultaneously is particularly important.In this study,we propose a graphical designing method(i.e.,thermal-electromagnetic surface transformation)based on thermal-electromagnetic null medium to simultaneously control the propagation of electromagnetic waves and thermal fields according to the pre-designed paths.A thermal-electromagnetic cloak,which can create a cloaking effect on both electromagnetic waves and thermal fields simultaneously,is designed by thermal-electromagnetic surface transformation and verified by both numerical simulations and experimental measurements.The thermal-electromagnetic surface transformation proposed in this study provides a new methodology for simultaneous controlling on electromagnetic and temperature fields,and may have significant applications in improving thermal-electromagnetic compatibility problem,protecting of thermal-electromagnetic sensitive components,and improving efficiency of energy usage for complex onchip systems.
基金supported by the National Key Research and Development Plan“Research on protection and restoration of typical small populations of wild plants”(Grant No.2016YFC0503106)。
文摘Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, the mRNA and metabolome sequencing of P. hopeiensis flower organs exposed to different low temperatures were performed to identify changes of genes and metabolites in response to low-temperature stress. A total of 4 851 differentially expressed genes(DEGs) were identified. Trend analysis showed that these DEGs were significantly enriched in profiles 19, 18, 7, 14, 1, 4 and 11. And the KEGG enrichment analysis showed that the DEGs in profile 18 were significantly enriched in flavone and flavonol biosynthesis. Besides, the expressed trends as well as GO and KEGG functional enrichment analyses of DEGs under cold and freezing stress showed significantly difference. Analyses of flavonoid-related pathways indicated that flavonoid structural genes had undergone significant changes. Correlation analysis showed that b HLH and MYB TFs may affect flavonoid biosynthesis by regulating structural gene expression. And PhMYB308 and PhMYB330 were likely candidate repressors of flavonoid biosynthesis by binding to a specific site in bHLH proteins. In total, 92 differentially accumulated metabolites(DAMs) were identified in P. hopeiensis flowers including 12 flavonoids. WGCNA results showed that coral 1, pink and brown 4 modules were closely associated with flavonoids and 11 MYBs and 15 bHLHs among the three modules may activate or inhibit the expression of 23 structural genes of flavonoid biosynthesis. Taken together, the results of this study provided a theoretical basis for further exploration of the molecular mechanisms of flavonoid biosynthesis and cold resistance of P. hopeiensis flower organs and our findings laid a foundation for further molecular breeding in cold-resistant pear varieties.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52072102 and 11775224)It was also partially funded through the Open Foundation of the Hefei National Laboratory for Physical Sciences at the Microscale(Grant No.KF2020002).
文摘Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures.Here,an MgO-based magnetic tunnel junction(MTJ)is chosen rationally as the ferromagnetic constitution and a high-activity(001)-Pb(Mg_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)O_(3)(PMN-0.3PT)single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure.The shape of tunneling magnetoresistance(TMR)versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias.The E-field-controlled change in the TMR ratio is up to-0.27%without magnetic-field bias.Moreover,when a typical magnetic field(~±10 Oe)is applied along the minor axis of the MTJ,the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias.This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ.In addition,based on such a multiferroic heterostructure,a strain-gauge factor up to approximately 40 is achieved,which decreases further with a sign change from positive to negative with increasing magnetic fields.This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.
基金supported by grants from the National Natural Science Foundation of China(No.51871239,No.32101087,No.52171244).
文摘Polyetheretherketone(PEEK)has been an alternative material for titanium in bone defect repair,but its clinical application is limited by its poor osseointegration.In this study,a porous structural design and activated surface modification were used to enhance the osseointegration capacity of PEEK materials.Porous PEEK scaffolds were manufactured via fused deposition modeling and a polydopamine(PDA)coating chelated with magnesium ions(Mg^(2+))was utilized on the surface.After surface modification,the hydrophilicity of PEEK scaffolds was significantly enhanced,and bioactive Mg^(2+)could be released.In vitro results showed that the activated surface could promote cell proliferation and adhesion and contribute to osteoblast differentiation and mineralization;the released Mg^(2+)promoted angiogenesis and might contribute to the formation of osteogenic H-type vessels.Furthermore,porous PEEK scaffolds were implanted in rabbit femoral condyles for in vivo evaluation of osseointegration.The results showed that the customized three-dimensional porous structure facilitated vascular ingrowth and bone ingrowth within the PEEK scaffolds.The PDA coating enhanced the interfacial osseointegration of porous PEEK scaffolds and the released Mg^(2+)accelerated early bone ingrowth by promoting early angiogenesis during the coating degradation process.This study provides an efficient solution for enhancing the osseointegration of PEEK materials,which has high potential for translational clinical applications.
基金National Key Research and Development Program of China(grant number 2017YFC1104900)National Natural Science Foundation of China(No.51871239,51771227,52171244 and 81772328)The authors also appreciate the support from the Incubation Project of the Army’s Medical Technology Youth Cultivation Program of China(17QNP021)。
文摘Biodegradable polycaprolactone/β-tricalcium phosphate(PT)composites are desirable candidates for bone tissue engineering applications.A higherβ-tricalcium phosphate(TCP)ceramic content improves the mechanical,hydrophilic and osteogenic properties of PT scaffolds in vitro.Using a dynamic degradation reactor,we estab-lished a steady in vitro degradation model to investigate the changes in the physio-chemical and biological properties of PT scaffolds during degradation.PT46 and PT37 scaffolds underwent degradation more rapidly than PT scaffolds with lower TCP contents.In vivo studies revealed the rapid degradation of PT(PT46 and PT37)scaffolds disturbed macrophage responses and lead to bone healing failure.Macrophage co-culture assays and a subcutaneous implantation model indicated that the scaffold degradation process dynamically affected macro-phage responses,especially polarization.RNA-Seq analysis indicated phagocytosis of the degradation products of PT37 scaffolds induces oxidative stress and inflammatory M1 polarization in macrophages.Overall,this study reveals that the dynamic patterns of biodegradation of degradable bone scaffolds highly orchestrate immune responses and thus determine the success of bone regeneration.Therefore,through evaluation of the biological effects of biomaterials during the entire process of degradation on immune responses and bone regeneration are necessary in order to develop more promising biomaterials for bone regeneration.
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China (Nos. 51102194, 51323011, and 51121092), the Doctoral Program of the Ministry of Education (No. 20110201120040) and the Nano Research Program of Suzhou City (ZXG2013003). S. Shen is supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China (No. 201335) and the Fundamental Research Funds for the Central Universities.
基金supported in part by the National Key R&D Program of China (No. 2018YFB0904600)in part by the National Nature Science Foundation of China (NSFC) under Grant 51677125
文摘A common method to examine the current-limiting performance of saturated iron-core fault current limiter(SI-FCL) in high-voltage direct-current transmission based on voltage source converter(VSC-HVDC) systems is to solve differential equations based on the system fault transient characteristics and the equivalent inductance calculation equation. This method analyzes the fault current of the VSC-HVDC system in the time domain. However, it is computationally complex and cannot directly reflect the relationship between parameters and the currentlimiting effect of the SI-FCL.In this paper,the relationship between the magnetic flux density and magnetic field energy of the SI-FCL is analyzed. The energy exchange between the DC capacitor and the SI-FCL in the DC short circuit fault process is analyzed. From the perspective of electromagnetic energy conversion, the criterion for determining the current-limiting ability of the SI-FCL in the transient process is given based on the parameters of the SI-FCL and VSC-HVDC system. On this basis, the characteristics of the DC side fault current and the capacitor voltage when the SI-FCL has current-limiting ability are examined.Based on the parameters of the SI-FCL and VSC-HVDC system, a method for calculating the fault current peak value and capacitor voltage drop time is given. Finally, the accuracy of the analysis of the SI-FCL in the VSC-HVDC system based on the electromagnetic energy conversion mechanism is demonstrated through a case study and simulation results of the VSC-HVDC system with different SI-FCLs.
基金National Natural Science Foundation of China(61905208,61971300)。
文摘An optical funnel,which performs as a passive electromagnetic compressor,can guide electromagnetic waves from a wide inlet to a narrow outlet without reflectance/scattering and squeeze electromagnetic fields uniformly to an air neck.In this study,an optical funnel is designed by precisely filling subwavelength ceramic blocks with a gradient refractive index inside a tapered waveguide.The gradient refractive index is designed by transformation optics,which is isotropic and all above unit,thus exhibiting a broadband feature.Due to the mechanism of impedance matching over the whole funnel,extremely low reflectance/scattering and stable enhancement of fields can be achieved.The field enhancement factor in different regions of the funnel(e.g.,in the air neck)can be flexibly designed just by modifying the funnel-width ratios.
基金supported in part by the National Natural Science Foundation of China (Nos. 61971300 and 61905208)the Scientific and Technological Innovation Programs (STIP) of Higher Education Institutions in Shanxi (Nos. 2019L0159 and 2019L0146)the National Key Research and Development Program of China (No. 2017YFA0205700)
文摘A novel way to design arbitrarily shaped retro-reflectors by optics surface transformation is proposed. The entire design process consists of filling an optic-null medium between the input and output surfaces of the retroreflector, on which the points have 180 deg reverse corresponding relations. The retro-reflector can be designed to be very thin(a planar structure) with high efficiency. The effective working angles of our retro-reflector are very large(from-80 deg to +80 deg), which can, in principle, be further extended. Layered metal plates and zero refractive index materials are designed to realize the proposed retro-reflector for a TM polarized beam.