Geodetic observations have shown that there exist large differences in the viscosity of the deep lithosphere across many large strike-slip faults.Heterogeneity in lithospheric viscosity structure can influence the eff...Geodetic observations have shown that there exist large differences in the viscosity of the deep lithosphere across many large strike-slip faults.Heterogeneity in lithospheric viscosity structure can influence the efficiency of stress transfer and thus may have a significant effect on the earthquake cycle.Until now,how the lateral viscosity variation across strike-slip faults affects the earthquake cycles is still not well understood.Here,we investigate the effects of across-strike viscosity variation on long-term earthquake behaviors with a three-dimensional strike-slip fault model.Our model is a quasi-static model which is controlled by the slip-weakening friction law and powerlaw rheology.By comparing with the reference case,we find that low viscosity on one side of the fault results in a smaller rupture area but with a higher Coulomb stress drop on the ruptured fault region.In addition,low viscosity also leads to a small Coulomb stress accumulation rate.These combined effects increase the earthquake recurrence interval by approximately 10%and the earthquake moments by about 30%when the low viscosity is related to a geothermal gradient of 30 K/km.In addition,across-strike viscosity variation causes asymmetric interseismic ground surface deformation rate.As the viscosity contrast increases,the difference in the interseismic ground surface deformation rate between the two sides of the fault gradually increases,although the asymmetric feature is not pronounced.This asymmetry of interseismic ground deformation rate across a strike-slip fault is supposed to result in asymmetric coseismic deformation if the long-term plate motion velocity is invariant.As a result,this kind of asymmetry of interseismic deformation may influence the evaluation of potential earthquake hazards along large strike-slip faults with lateral viscosity contrast.展开更多
The study of postseismic deformation is important for constraining the viscoelastic properties of the Earth and inverting the post-earthquake process.The levelling survey revealed that the area near Bei-chuan elevated...The study of postseismic deformation is important for constraining the viscoelastic properties of the Earth and inverting the post-earthquake process.The levelling survey revealed that the area near Bei-chuan elevated 5.3 cm about two years after the M_(W) 7.9 Wenchuan earthquake(05/12/2008),during which the area underwent significant downward movement.The GPS horizontal displacements showed a non-monotonic variation after the Wenchuan earthquake.In this study,a 3-D viscoelastic finite element model is employed to simulate the coseismic and postseismic deformation of the Wenchuan earthquake.The numerical simulations show that the lateral heterogeneity across the Longmenshan fault plays an important role in the postseismic displacements.The results reveal that the coseismic defor-mation is not sensitive to the horizontal heterogeneity,but the postseismic deformation is sensitive to it.The postseismic deformation of the horizontally heterogeneous model is generally consistent with the observations of all geodetic surveys,such as GPS,InSAR and levelling,but not for the horizontally homogenous model.We also find that the non-monotonous variation of the postseismic deformation of the Wenchuan earthquake could be explained by a viscoelastic relaxation model with lateral heterogeneous medium across the Longmenshan fault.展开更多
Ligustrum purpurascens has been used as a traditional herb for over 2,000 years in China.This study was design to investigate the modulation of antiviral cytokines and reduction in lung inflammation of virus-infected ...Ligustrum purpurascens has been used as a traditional herb for over 2,000 years in China.This study was design to investigate the modulation of antiviral cytokines and reduction in lung inflammation of virus-infected mice by the glycosides isolated from Ligustrum purpurascens.Methods:Ligustrum purpurascens glycosides(LPG)were isolated from the leaves of Ligustrum purpurascens.Proliferation of spleen lymphocytes were investigated after LPG treatment.The in vitro and in vivo cytokine modulation of LPG was studied.Furthermore,the anti-inflammatory and antiviral activities of LPG,with the potential to reduce inflammatory lung disorders,were investigated by influenza A virus infected mice.Results:LPG could significantly promote the proliferation,and also could stimulate the production of IFN-γby spleen lymphocytes in a dose-dependent manner.IFN-γexpression level was increased significantly compared to the control and presented a dose-dependent manner in vitro.Furthermore,LPG inhibit the expression of TNF-αand IL-10,which return to normal level in the cyclophosphamide-induced mice model in vivo.Besides,the histopathological analysis indicated LPG reduced acute lung injury in mice infected with influenza virus.Conclusion:This study suggested that LPG could increase the exression of IFN-γ,immunoregulation and decrease lung inflammation of virus-infected mice.展开更多
There has been growing interest in the high-entropy ceramic(HEC)recently owing to its tailorable compositions and microstructures,versatile properties,together with promising structural and functional applications.How...There has been growing interest in the high-entropy ceramic(HEC)recently owing to its tailorable compositions and microstructures,versatile properties,together with promising structural and functional applications.However,inferior fracture toughness(KIC)and damage tolerance restricted many practical applications of the HEC.Herein,we addressed this challenge by incorporating a threedimensional graphene–carbon nanotube(3D G–CNT)as toughening agent in(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.The resulting enhanced 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C featured an outstanding toughness of 8.23 MPa·m^(1/2),while remaining superior strength(763 MPa)and hardness(24.7 GPa).An ultralow friction coefficient(0.15)coupled with an ultralow wear rate(w,2.6×10^(−7) mm^(3)/(N·m))in the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C was obtained primarily as a function of lubricating scrolls,in which two-dimensional(2D)graphene acted as a tribolayer,and one-dimensional(1D)carbon nanotubes acted as nano ball bearings embedded inside.Strikingly,the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C exhibited rather low thermal conductivity(κ)yet excellent electrical conductivity(σ,1.3×10^(6) S/m)in comparison with the pure(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.This study provided great potential for maximizing the physical and functional properties of the HEC for various applications.展开更多
With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based ...With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based underwater acoustic communication system using dual spread spectrum code is proposed. To solve the contradictions between the information data rate and the accuracy of Doppler estimation, channel estimation, and frame synchronization, a data frame structure based on dual spread spectrum code is designed. A long spread spectrum code is used as the training sequence, which can be used for data frame detection and synchronization, Doppler estimation, and channel estimation. A short spread spectrum code is used to modulate the effective information data. A delay cross-correlation algorithm is used for Doppler estimation, and a correlation algorithm is used for channel estimation. For underwater networking, each user is assigned a different pair of spread spectrum codes. Simulation results show that the system has a good anti-multipath, anti-interference, and anti-Doppler performance, the bit error rate can be smaller than 10^(-6) when the signal-to-noise ratio is larger than-10 dB, the data rate can be as high as 355 bits/s, and the system can be used in the downlink of CDMA based networks.展开更多
CT： Artificial tissue engineering scaffods can potentially provide supportand guidance for the regrowth of severed axons following nerve injury. In this study a hybrid biomaterial composed of alginate and hyaluronic ...CT： Artificial tissue engineering scaffods can potentially provide supportand guidance for the regrowth of severed axons following nerve injury. In this study a hybrid biomaterial composed of alginate and hyaluronic acid （HA） was synthesized characterized in terms of its suitability for covalent modification, biocompatibility fir living Schwann cells and feasibility to construct three dimensional （3D） Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calcium ions that ionically crosslink alginate.Amide formation was found to be dependent on the concentrations of cabodiimide and calclum chloride. The double-crosslinked composite hydrogels display blocompatibllity that is comparable to simple HA hydrogels, allowing for Schwann cell survival and significant difference was found between composite hydrogels made from different of alginate and HA. A 3D BioPIotterTM rapid prototyping system was used to fabricats 3D scaffolds. The result indicated that combining HA with alginate facilitated the fabrication process and that 3D scaffolds with porous inner structure can be fabricated ;from the composite hydrogels, but not from HA alone. This information provides a basis for continuing in vitro and in vivo tests of the suitability of alginate/HA hydrogel as a biomaterial to create living cell scaffolds to support nerve regeneration.展开更多
基金supported by the National Natural Science Foundation of China (4207410592155204)the Joint Open Fund of Mengcheng National Geophysical Observatory (No. MENGO-202004)
文摘Geodetic observations have shown that there exist large differences in the viscosity of the deep lithosphere across many large strike-slip faults.Heterogeneity in lithospheric viscosity structure can influence the efficiency of stress transfer and thus may have a significant effect on the earthquake cycle.Until now,how the lateral viscosity variation across strike-slip faults affects the earthquake cycles is still not well understood.Here,we investigate the effects of across-strike viscosity variation on long-term earthquake behaviors with a three-dimensional strike-slip fault model.Our model is a quasi-static model which is controlled by the slip-weakening friction law and powerlaw rheology.By comparing with the reference case,we find that low viscosity on one side of the fault results in a smaller rupture area but with a higher Coulomb stress drop on the ruptured fault region.In addition,low viscosity also leads to a small Coulomb stress accumulation rate.These combined effects increase the earthquake recurrence interval by approximately 10%and the earthquake moments by about 30%when the low viscosity is related to a geothermal gradient of 30 K/km.In addition,across-strike viscosity variation causes asymmetric interseismic ground surface deformation rate.As the viscosity contrast increases,the difference in the interseismic ground surface deformation rate between the two sides of the fault gradually increases,although the asymmetric feature is not pronounced.This asymmetry of interseismic ground deformation rate across a strike-slip fault is supposed to result in asymmetric coseismic deformation if the long-term plate motion velocity is invariant.As a result,this kind of asymmetry of interseismic deformation may influence the evaluation of potential earthquake hazards along large strike-slip faults with lateral viscosity contrast.
基金This work is supported by the National Natural Science Foun-dation of China(42074105,41674096)Natural Science Foundation of Jiangsu Province(BK20131033)。
文摘The study of postseismic deformation is important for constraining the viscoelastic properties of the Earth and inverting the post-earthquake process.The levelling survey revealed that the area near Bei-chuan elevated 5.3 cm about two years after the M_(W) 7.9 Wenchuan earthquake(05/12/2008),during which the area underwent significant downward movement.The GPS horizontal displacements showed a non-monotonic variation after the Wenchuan earthquake.In this study,a 3-D viscoelastic finite element model is employed to simulate the coseismic and postseismic deformation of the Wenchuan earthquake.The numerical simulations show that the lateral heterogeneity across the Longmenshan fault plays an important role in the postseismic displacements.The results reveal that the coseismic defor-mation is not sensitive to the horizontal heterogeneity,but the postseismic deformation is sensitive to it.The postseismic deformation of the horizontally heterogeneous model is generally consistent with the observations of all geodetic surveys,such as GPS,InSAR and levelling,but not for the horizontally homogenous model.We also find that the non-monotonous variation of the postseismic deformation of the Wenchuan earthquake could be explained by a viscoelastic relaxation model with lateral heterogeneous medium across the Longmenshan fault.
基金This study was supported by the Natural Science Foundation of the Education Department of Guangdong Province(2020KZDZX1172)Guangdong Basic and Applied Basic Research Fund(2020A1515111169)+1 种基金National Natural Science Foundation of China(NSFC,31670360 and U1702286)Natural Science Foundation of SZU 860-000002110131.
文摘Ligustrum purpurascens has been used as a traditional herb for over 2,000 years in China.This study was design to investigate the modulation of antiviral cytokines and reduction in lung inflammation of virus-infected mice by the glycosides isolated from Ligustrum purpurascens.Methods:Ligustrum purpurascens glycosides(LPG)were isolated from the leaves of Ligustrum purpurascens.Proliferation of spleen lymphocytes were investigated after LPG treatment.The in vitro and in vivo cytokine modulation of LPG was studied.Furthermore,the anti-inflammatory and antiviral activities of LPG,with the potential to reduce inflammatory lung disorders,were investigated by influenza A virus infected mice.Results:LPG could significantly promote the proliferation,and also could stimulate the production of IFN-γby spleen lymphocytes in a dose-dependent manner.IFN-γexpression level was increased significantly compared to the control and presented a dose-dependent manner in vitro.Furthermore,LPG inhibit the expression of TNF-αand IL-10,which return to normal level in the cyclophosphamide-induced mice model in vivo.Besides,the histopathological analysis indicated LPG reduced acute lung injury in mice infected with influenza virus.Conclusion:This study suggested that LPG could increase the exression of IFN-γ,immunoregulation and decrease lung inflammation of virus-infected mice.
基金supported by the National Natural Science Foundation of China (No.52005396)Young Talent Fund of University Association for Science and Technology in Shaanxi (No.20210414)Qilu Youth Scholar Project Funding of Shandong University (No.1050522300003).
文摘There has been growing interest in the high-entropy ceramic(HEC)recently owing to its tailorable compositions and microstructures,versatile properties,together with promising structural and functional applications.However,inferior fracture toughness(KIC)and damage tolerance restricted many practical applications of the HEC.Herein,we addressed this challenge by incorporating a threedimensional graphene–carbon nanotube(3D G–CNT)as toughening agent in(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.The resulting enhanced 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C featured an outstanding toughness of 8.23 MPa·m^(1/2),while remaining superior strength(763 MPa)and hardness(24.7 GPa).An ultralow friction coefficient(0.15)coupled with an ultralow wear rate(w,2.6×10^(−7) mm^(3)/(N·m))in the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C was obtained primarily as a function of lubricating scrolls,in which two-dimensional(2D)graphene acted as a tribolayer,and one-dimensional(1D)carbon nanotubes acted as nano ball bearings embedded inside.Strikingly,the 3D G–CNT/(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C exhibited rather low thermal conductivity(κ)yet excellent electrical conductivity(σ,1.3×10^(6) S/m)in comparison with the pure(Hf_(0.2)Nb_(0.2)Ta_(0.2)Ti_(0.2)Zr_(0.2))C.This study provided great potential for maximizing the physical and functional properties of the HEC for various applications.
基金Project supported by the National Natural Science Foundation of China(Nos.61431005,51409235,and 61401111)the Fundamental Research Funds for the Central Universities,China(No.201213004)
文摘With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based underwater acoustic communication system using dual spread spectrum code is proposed. To solve the contradictions between the information data rate and the accuracy of Doppler estimation, channel estimation, and frame synchronization, a data frame structure based on dual spread spectrum code is designed. A long spread spectrum code is used as the training sequence, which can be used for data frame detection and synchronization, Doppler estimation, and channel estimation. A short spread spectrum code is used to modulate the effective information data. A delay cross-correlation algorithm is used for Doppler estimation, and a correlation algorithm is used for channel estimation. For underwater networking, each user is assigned a different pair of spread spectrum codes. Simulation results show that the system has a good anti-multipath, anti-interference, and anti-Doppler performance, the bit error rate can be smaller than 10^(-6) when the signal-to-noise ratio is larger than-10 dB, the data rate can be as high as 355 bits/s, and the system can be used in the downlink of CDMA based networks.
文摘CT： Artificial tissue engineering scaffods can potentially provide supportand guidance for the regrowth of severed axons following nerve injury. In this study a hybrid biomaterial composed of alginate and hyaluronic acid （HA） was synthesized characterized in terms of its suitability for covalent modification, biocompatibility fir living Schwann cells and feasibility to construct three dimensional （3D） Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calcium ions that ionically crosslink alginate.Amide formation was found to be dependent on the concentrations of cabodiimide and calclum chloride. The double-crosslinked composite hydrogels display blocompatibllity that is comparable to simple HA hydrogels, allowing for Schwann cell survival and significant difference was found between composite hydrogels made from different of alginate and HA. A 3D BioPIotterTM rapid prototyping system was used to fabricats 3D scaffolds. The result indicated that combining HA with alginate facilitated the fabrication process and that 3D scaffolds with porous inner structure can be fabricated ;from the composite hydrogels, but not from HA alone. This information provides a basis for continuing in vitro and in vivo tests of the suitability of alginate/HA hydrogel as a biomaterial to create living cell scaffolds to support nerve regeneration.
